Research students
PhD STUDENTS ON GOING
RESEARCH TITLE: Massive MIMO Antenna design for 5 G application
Researcher : Abd A Menam Ahmed Jasim Al Azzawi (Main Supervisor)
Abstract:
As known the last ten years a massive growth in the number of connected wireless devices. Billions of devices are connected and managed by wireless networks. At the same time, each device needs a high throughput to support applications such as voice, real-time video, movies, and games. Demands for wireless throughput and the number of wireless devices will always increase. In addition, there is a growing concern about energy consumption of wireless communication systems. Thus, future wireless systems have to satisfy three main requirements: i) having a high throughput; ii) simultaneously serving many users; and iii) having less energy consumption. Massive multiple-input multiple-output (MIMO) technology, where a base station (BS) equipped with very large number of antennas (collocated or distributed) serves many users in the same time-frequency resource, can meet the above requirements, and hence, it is a promising candidate technology for next generations of wireless systems. With massive antenna arrays at the BS, for most propagation environments, the channels become favorable, i.e., the channel vectors between the users and the BS are (nearly) pair wisely orthogonal, and hence, linear processing is nearly optimal. A huge throughput and energy efficiency can be achieved due to the multiplexing gain and the array gain. In particular, with a simple power control scheme, Massive MIMO can offer uniformly good service for all users.in general as an abstract massive MIMO antenna system would contains many elements of antennas (minimum 64element), power divider (with SIW technology due to high frequencies that’s will be chosen) and beamformer. so as to study all the parameters after and before combined the whole system together and check the effect of each other.
RESEARCH TITLE: Mm Wave lens antenna with microwave feeding technique for 5G application
Researcher: Nor Saidah Mohd Nadzir (main supervisor)
Abstract:
Millimeter wave frequency antennas offers the advantage of contributing to overall system compactness, has a scaled-down antenna size, and wide accessible bandwidth. Due to their appealing features such as lightweight, cost-effective in terms of production cost, ease of fabrication and integration, planar antennas such as microstrip and printed circuit antenna are largely adopted in the millimeter wave system. Nevertheless an increase in free-space path loss will always present itself when developing high frequency antennas. However, beamforming structures are one of the possible solutions to counter the free-space path loss at millimeter wave frequency. Thus, this research focuses on the development of millimeter wave lens antenna with microwave feeding technique that operates at 26 GHz for 5G application. The antennas are designed and simulated using Computer Simulation Technology (CST) software and tools. Initial results shows promising future as designed antennas produced gain from 7.87 dBi for the single element antenna to 18.2 dBi for 4 x 4 array antenna with sizes from 8 mm x 8 mm up to 35 mm x 35 mm respectively
RESEARCH TITLE: Multibeam antenna for 5G applications at mmWave frequency
Researcher: Hatem O. Hanoosh (main supervisor)
Abstract
In this work the focus is on designing of a multibeams waveguide slot antenna with bemforming network for 5G application. The multi-beams radiation is proposed to expand the coverage of the single antenna, thus more capacity is enabled. Waveguide slots antenna is a well-known antenna for high power and gain transmission capabilities. Therefore, it is preferred. In this work, four variations of waveguide slots antennas are studied. The slot distribution covers one to four broad and narrow walls of the waveguide. This technique enables multi-beams patterns. The performance of the proposed antennas is simulated using CST microwave software. The simulated responses of the antennas show that a good matched with return loss greater than 10 dB at the desired frequency. The four proposed antennas achieved a good gain between 6.3 and 7.4 dB with directional beamwidth of 15 degree.
RESEARCH TITLE: Metamaterial Nolen Matrix Beamforming for 5G Mobile Applications.
Researcher: Hussam Hamid Abed (main supervisor)
Abstract
Currently, fifth generation technology (5G) are adopted to reduce the multi-paths propagation and increases the gain, bandwidth, and directivity toward the desired direction. Malaysia Communication and Multimedia Commission (MCMC) proposed 3.5 GHz for the next 5G mobile spectrum. The needs to design a compact wideband antenna beamforming with high gain realizing the 5G proposed spectrum in Malaysia are urgently demanded. To overcome these challenges, beamforming networks such as Butler matrix and Nolen matrix are proposed. This research presents a Nolen beamforming based on metamaterial technology for 5g mobile applications due to its simplicity and no Crossovers are needed in its structure competed to other matrixes. Nolen matrix consists of directional couplers and phase shifter only. This could reduce the size of the proposed beam former and reduces the losses as well. Generally, microstrip technology suffers from high loss in the beam shifting and low front to back ratio. These limitations and drawbacks can be considerate also as main challenges in designing antenna beamforming based on microstrip in the 5G proposed low frequency. The metamaterial-inspired structures can provide a good way to help antennas achieve the expected multiband or frequency tuneable characteristics beside high gain capability. Therefore, this work presents two methods. Firstly, the microstrip antenna is developed at 3.5 GHz with acceptable bandwidth and gain more than 5 dB. Secondly, the metamaterial unit cell is designed individually based on split ring resonator (left handed metamaterial) SRR LHM type. Then integrated with the developed antenna at 3.5 GHz. That will increase the bandwidth and the gain accordingly. The proposed designs are simulated and optimized using CST software. The initial simulated results of the proposed designs show a good return loss of greater than 10 dB and a bandwidth of more than 1 GHz. The antenna has a gain of 7 dB. This one year study is giving a promising results for the implementation of full Nolen beamforming with metamaterial at MCMC proposed bands (3.5 GHz) for 5g mobile applications.
RESEARCH TITLE : Antenna With Beamforming Network Using Substrate Integrated Waveguide For Wireless Communication
Researcher: Yaqdhan Mahmood Hussein (main supervisor)
Abstract
The fifth generation (5G) and millimeterwave technology are urgently needed to provide huge data rates, high gain and high directivity radiation pattern beams. Therefore, beamforming networks (BFNs) are introduced to provide these needs. Butler matrix (BM) is a type of beamforming network, which can be realized using fixed network circuits and feeds the antenna array. BM at higher frequencies suffers from components loss and phase errors especially when it is implemented using microstrip structures. Different transmission lines such as waveguide and substrate integrated waveguide (SIW) are studied and introduced for realizing Butler matrix. SIW structures are good candidate for implementation of BM due to its property of low loss transmission line comprises the properties of microstrip and waveguide technology. However, SIW antennas and structures at millimeterwave have unwanted radiation losses comes from the vias holes. In addition, the vias separation distance is depended on waveguide size, which leads to a bigger size for massive beamforming network at millimeterwave. Hence, this work proposed a compact size and optimal SIW antenna beamforming structure to reduce the vias losses and provides higher bandwidth and gain at 26 GHz. The proposed designs will be simulated using CST software and fabricated by PCB LPKF ProtoMat printer. The outcomes of wide bandwidth more than 1 GHz and high directive gain better than 10 dB for the beamforming network are expected
RESEARCH TITLE: FRACTAL FREQUENCY SELECTIVE SURFACE FOR BANDWIDTH ENHANCEMENT
Researcher : Nur Biha Mohamed Nafis (Main supervisor)
Abstract
The Frequency Selective Surface (FSS), also known as a spatial filter, is an infinite periodic array that either made up of metallic patch or slot aperture elements, able to exhibit the filtering characteristics such as transmission and reflection based on the element structure when EM wave incident onto it. Recently, there is a competitive demand for the frequency selective surface (FSS) designs that meet the important criteria - multiband, broad bandwidth and insensitive to oblique angles, for thwarting the electromagnetic interference (EMI). The possibility of EMI especially between frequencies ranging from 0.7 GHz to 2.6 GHz where most of the wireless communication systems such as mobile phone, is raising the concern of equipment failure especially for medical equipment, clinical laboratory instrument (Radiofrequency Interference in the Clinical Laboratory) and etc. Instead of using the traditional FSS, fractal structure implemented FSS (FFSS) such as Koch, Minkowski, and etc, helps for the enhancement of the FSS structure performance by offering a better frequency response such as multiband and broad bandwidth behaviors, in smaller dimension of size for fulfillment of the compactness requirement. The FFSS structure employed the self-similarity feature, allowed the longer electrical length of FSS structure to be confined in a specified area or volume. Thus, the best performance of the filter that meets all the important requirement can be established. The utilization of compact FFSS is widely explored for many applications such as radome, EMI protection, dish antenna dichroic feeds, avionics antenna, autonomous vehicle demonstration system and etc
RESEARCH TITLE: RECONFIGURABLE FSS BASED CIRCULAR POLARIZED, LOW PROFILE, HIGH GAIN TRANSMITARRAY ANTENNA FOR 5G COMMUNICATION SYSTEMS
Researcher: Muhammad Naeem Iqbal (Co supervisor)
Abstract
The future Fifth Generation (5G) wireless communication systems require research on low profile and high gain RF Front ends especially antennas. This has resulted in the research on high gain antennas while keeping their structures to be low profile. As compared to the conventional reflectarray antennas which have the drawback of main beam hindrance, this work will be based upon the transmitarray antennas in which the main beam hindrance problem will be solved as well as amplification, beam steering and the linear to circular polarization conversion using the frequency selective surfaces will be achieved. Initially, different transmitarray unit cell designs will be modeled in CST Microwave studio and their simulated results will be compared to find out best suitable designs keeping in view their multi-layer structures, complexity of FSS designs and integration of active devices in the FSS based transmitarray unit cells for beam switching applications. The parametric studies will be performed on the unit cell designs in CST to obtain phase ranges in the range of 360 degrees. Afterwards, the selected novel unit cell designs will be used to design multilayer transmitarrays. This will include the design of wideband horn antenna, focal distance to diameter ratio optimization in complete design and inter layer spacing. In order to convert the polarization of the designed Transmitarray, linear to circular polarization conversion layer using meander line unit cell will be designed. The effect of polarization converter layer in terms of axial ratio, gain of the transmitarray and radiation pattern will be analyzed. Finally, in order to achieve the reconfigurability in terms of main beam switching, different techniques will be compared in terms of mechanical as well as electronic switching. The incorporation of active switching devices like PIN diodes and varactors in transmitarray unit cells and subsequently the complete transmitarray will also be implemented. The characterization of fabricated transmitarray will be carried out in anechoic chamber available in Advanced Microwave and Antenna Laboratory at UTM and measured results will be compared with the simulated results for verification purpose. The proposed FSS based reconfigurable, low-profile, wideband, circularly polarized transmitarrays find applications in future 5G wireless communication systems
RESEARCH TITLE: DESIGN OF HIGHLY EFFICIENT POWER AMPLIFIER IN BASE STATION FOR LTE BANDS APPLICATIONS
Researcher: Khirul Hilmi Yusof (Co supervisor)
Abstract
As telecommunications technology becomes grows more sophisticated and complex over the past decade, the growing of this sector is inevitable. We are now approaching the 5G which cover theoretical speeds up to 10 gigabit per seconds wirelessly. So the needs of a highly efficient device for today industry skyrocketed. A highly efficient device will ensure the device operate longer when powered using battery. One of the main components that consume a lot of energy is a power amplifier (PA). An inefficient PA can reduce mobile device operation time. For a PA to be working efficiently, a suitable output matching network that can work in Sub-6 GHz frequency is needed. So, in this research a highly efficient power amplifier class such as Class E was chosen as it has a 100% theoretical efficiency. In order for the output matching network of the PA to cover the Sub-6 GHz band, methods such as switch band and wideband matching network is considered. The expected outcomes of this research are a power amplifier is working in the Sub-6 GHz frequency and has more than 60% power added efficiency. As a summary, the outcome of this research can be used in a variety of industry, such as automotive, telecommunications, and etc. due to the demand of highly efficient power amplifiers design
RESEARCH TITLE: BEAMFORMING NETWORK USING METAMATERIAL STRUCTURE
Researcher: Arshad Karimbu (Main supervisor)
Abstract
Multibeam antennas have become a key element in nowadays wireless communication systems where increased channel capacity, improved transmission quality with minimum interference and multipath phenomena are severe design constraints. With the maturity and deployment of 4G long-term evolution (LTE) system and the ever-increasing requirements on the rate of data signaling, study on 5G has been put on the researchers’ agenda worldwide. To achieve both high-gain and wide coverage areas for possible 5G mobile terminals, the use of the phased array and multibeam schemes are promising candidates at the moment. These Multi beam antennas are classified in two main categories namely adaptive smart antennas and switched-beam antennas. Switched-beam antennas consist of an elementary antenna array connected to a Multiple Beam Forming Network (M-BFN).Among the different M-BFNs, the Butler matrix has received particular attention as it is theoretically lossless and employs the minimum number of components to generate a given set of orthogonal beams (provided that the number of beams is a power of 2). However, the Butler matrix has a main design problem which is the narrow bandwidth and presence of path crossings. So the butler matrix for 5G research has been focusing on the miniaturization and improving the bandwidth. Artificial Transmissions Lines is a relatively new method that achieves miniaturization of a transmission line through periodically loading the line capacitively in order to lower the phase velocity characteristic of a high impedance line to an appropriate value. Metamaterial transmission line based components combine the advantages of miniaturization, improving the bandwidth, low insertion loss and high power capability while being compatible with low-cost PCB. Owing to its attractive features, the use of metamaterial transmission lines appears as a good candidate for the implementation of BFNs for 5G communication. In this project, different novel passive components (couplers , crossover and phase shifters) have been developed exploring the metamaterial transmission line towards the implementation of a two-layer compact 4×4 Butler matrix offering wideband performances for both transmission magnitudes and phases with good isolation and input reflection characteristics.
RESEARCH TITLE: FREQUENCY RECONFIGURABLE METAMATERIAL ANTENNA FROM WIDEBAND TO NARROWBAND AND MULTIBAND
Researcher: Adamu Y Illiyasu (Co supervisor)
Abstract
This research work presents the design of wideband frequency reconfigurable metamaterial antenna. The design is based on resonant and transmission line techniques of metamaterial antenna design. The demand of portable communication devices is due to rapid development of wireless communication devices such as computers, mobile phones and other related portable devices and increasing number of users. These lead to challenges like high cost of design, size reduction, limited bandwidth, insufficient operating bands, spectrum congestion and interference. Design of single, high efficient antenna for multi-bands operations is one of the crucial challenges to be accomplished by the designer of every wireless communication system. Therefore, wideband reconfigurable metamaterial antenna might be a good solution in this regard. The fundamental objective of this research is to design wideband frequency reconfigurable metamaterial antenna with operating bandwidth (1.5-6.0 GHz) for multi frequency operation with overall dimension equivalent to resonating length. at 5.2GHz, 2.4GHz and 2.3GHz respectively. The ultimate objective at the end of the design is to achieve compactness, wider bandwidth, several operating bands, and improve spectrum utilization. The research will focus based on the investigation and literature review of the previous work, these investigations include the study and understanding the algorithm of metamaterial antenna design and frequency reconfiguration techniques. The design is divided into two, the first one is related to the manipulation of Computer Simulation Technology (CST) software for computational design of the existing work. The second one is related to the design, simulation and manufacturing of the real prototype of the software design of proposed antenna for measurement, comparison and validation with existing work. Some preliminary results by improving the existing work were obtained which includes, Wide-Band Metematerial Antenna, Wide-Band Frequency Reconfigurable Metamaterial antenna, Multi-Band Frequency Reconfigurable Metamaterial Antenna, and Wideband Metamaterial Antenna with Rectangular Rings. To be more specific, the main target is to design antenna to operate at 2.4GHz(2.4-2.484GHz) and 5.2GHz(5.15-5.35GHz) for WLAN application, and (2.5-2.69GHz) bands for LTE application
RESEARCH TITLE: WIDEBAND AND MULTIBAND ANTENNA WITH FREQUENCY RECONFIGURABILITY FOR MULTIMODE APPLICATION
Researcher: Izni Husna Idris (Co supervisor)
Abstract :
The Reconfigurable Antenna (RA), is an antenna which have capability to changing its frequency, radiation, polarization and other properties. Developments of reconfigurable antennas in wireless communication systems are still growing and received a lot of new attention from many researcher nowadays. In frequency reconfigurable antennas, there are many types of reconfigurations. Most reported antennas can be switched between narrow-to-narrowband, multi-to-multiband and wide-to-wideband reconfigurations. In this research, an antenna is proposed with the ability to produce a narrowband to multiband and wideband reconfiguration. The proposed antenna is able to suppress the problem of co-site interferences thus can operate in multimode applications. Switching technique using pin-diode switches is used to switch the operating frequency. The proposed antenna should be able to work in narrowband (1.8 GHz and 2.6 GHz, separately), multiband (1.8 GHz and 2.6 GHz, continously) and wideband (3.0 GHz to 9.0 GHz) mode when the certain configuration of pin-diode switches is selected. This research is suitable to be used in telecommunication industry such as multimode wireless communications systems.
RESEARCH TITLE : ON BODY ABSORPTION COUPLING EFFECTS AND CHARACTERIZATION OF FABRIC ANTENNAS OPERATING AT 2 GHZ TO 12 GHz FREQUENCY BANDS
Researcher : NORFATIN AKMA BINTI ELIAS (Co supervisor))
Abstract :
Utilization of textile materials for the wearable antenna applications has been rapid due to the recent miniaturization of wireless devices. Therefore electromagnetic field absorption is becoming an important public concern on potential health hazard. This research project tends to investigate the interaction between electromagnetic field radiated and antenna in terms of the antenna performance and electromagnetic energy absorption by human body in terms of Specific Absorption Rate (SAR). Conventionally, the SAR value is investigated for conventional flat and rigid antenna, however, under an on-body environment it is difficult to keep the textile antenna in a flat condition all of the time. It is therefore necessary to evaluate the textile antenna’s performance and the SAR value under bending and crumpling conditions. Therefore, further intensive study in terms of SAR value and characterization of fabric antenna performance by considering the effect of bending, crumpling, different textile materials, different orientations and different positions on human body will be investigated in this project. In the end of the research, some references and guideline will be proposed in order to improve the current antenna design so that it can eliminate or reduce the effect of human body and works fine under bending or crumpling conditions.
RESEARCH TITLE: CHIPLESS RFID SENSOR
Researcher: MOHD EZWAN JALIL (Main supervisor)
Abstract:
Radio Frequency Identification (RFID) uses wireless radio frequency system to transfer data for identifying purposes and tracking of tag activities. The RFID system has been implemented for various applications such as in payment systems, access control and asset tracking. The RFID system elements consists of active reader which transmit encoded signal to interrogate the tag, transponder (tags), and subsequently store the ID information in integrated circuit that stores and processes the radio-frequency signal. However, production of RFID tag is high in cost due to the presence of Application Specific Integrated Circuit (ASIC) chip. Recently, researchers are focusing in designing a compact and low cost chip less RFID system without the implementation of ASIC. The chip-less RFID system specification is based on the transponder which uses the electromagnetic properties and design of various structure to perform data encoding without the need of ASIC chip. There are two types of transponder which are the time domain reflectometry (TDR) such as surface acoustic wave (SAW) tag and spectral signature such as capacitive tuned dipole, space filling curves and LC resonant. However, the a fore mentioned technique cannot be applied on fully printable material such as bank note and postage stamp due to the piezoelectric nature of SAW tag. The Chip-less RFID tags is based on LC resonant has been proposed using spit-wheel, microstrip open stub and spurline techniques.In this project, the novel flexible and compact chipless RFID are proposed. A new technique based metamaterial has been proposed to represent the bit of ID tag number across the Ultra-wideband frequency. Then, the performances of flexible chipless tags on human body are evaluated
RESEARCH TITLE : TRANSMISSION MODELLING FOR WEARABLE APPLICATION USING DUAL BAND AMC ANTENNA
RESEARCHER : Muhammad Azfar Abdullah (Main supervisor)
Abstract:
Modeling of on-body propagation channels is of paramount importance to those wishing to evaluate radio channel performance for wearable devices in body area networks (BANs). Difficulties in modeling arise due to the highly variable channel conditions related to changes in the user’s state and local environment. This study characterizes these influences by using frequency-domain analysis to examine and model signal characteristics for on-body radio channels in user stationary and mobile scenarios in four different locations: anechoic chamber, open office area, hallway, and outdoor environment. The sheet-like waveguide are used to provide an independent transmission path which can reduce all distortions caused by human body. The proposed AMC waveguide sheet consists of textile substrate with radiating patches and ground plane made of conductive fabric. The flexibility of textile material make it suitable for wearable communications. The transmission characteristics between antennas was studied rigorously in this work. Transmission loss between the antennas have been significantly reduced apart from minimizing the radiation towards human body
RESEARCH TITLE: TWISTED PAIR COPPER CABLE CHARACTERIZATION FOR NEXT GENERATION ACCES IN MALAYSIA
Researcher: AZHARI ASROKIN (Main supervisor)
Abstract:
The purposes of the research is to study and generate a twisted pair copper cable modelling for the future generation of digital subscriber line (DSL) such as G.fast (acronym for Gigabit Fast Access to Subscriber Terminal) with capability of carrying 1Gbps aggregated data on copper cable used by Telekom Malaysia (TM). The research will involve the study on the effect of different cable gauge used by TM, ideal line and non-ideal condition which will be simulated in commercial software such as Matlab and/or CST Microwave Studio. The latest copper technology provided to the customer in Malaysia is the VDSL technology are especially catered to the high rise building which came from the fiber-to-the-curb (FTTC) or fiber-to-the-distribution point (FTTdp) access. The current copper cables deployed to the customer premises in Malaysia are mainly consisting of CAT3 cables which are meant to operate only up to 16MHz. The G.fast standard aims to operate beyond ADSL (< 2MHz) and VDSL (<30MHz) which can be up to 106 or 212 MHz, a study need to be done to characterize the laid copper cable to observe whether the current copper cable can support the new standard. Impairments at higher frequencies are also not yet modelled properly. The two most common impairments occurred in copper network would be the bridge tap and cable imbalance. The research is expected to produce characterized model of the existing TM’s copper cable network within G.FAST new frequency bandwidth from 2 MHz to 250 MHz which include secondary parameters (scattering parameters, gamma and characteristic impedance, Z0) and primary parameters (resistance, inductance, conductance and capacitance). The research will also recommend the ideal cable characterization reference to support G.FAST system which the reference will be used as a pre-qualification standard before any new copper cable network are being deployed or purchased.
RESEARCH TITLE: FREQUENCY RECONFIGURABLE METAMATERIAL ANTENNA
Researcher: ARRAUZAH RAZAK (Main supervisor)
Abstract
In the recent years, electromagnetic metamaterials (MTMs) are widely used for antenna applications. MTMs exhibit some specific features which are not found in the conventional material. Thirty years later, Sir John Pendry proposed conductor geometries to form a composite medium which exhibits effective values of negative permittivity and negative permeability. Based on the unique properties of MTMs, many novel antenna applications of these materials have been developed. The use of MTMs could enhance the radiated power of an antenna. Negative permittivity and permeability of these engineered structures can be utilized for making electrically small antenna, highly directive, and reconfigurable antennas. Reconfigurable antennas change polarization, operating frequency, or far-field pattern in order to cope with the changing of system parameters. Antenna reconfiguration is normally achieved in one of three ways; switching parts of the antenna structure in or out using electronic switches, adjusting the loading or matching of the antenna externally, or changing the antenna geometry by mechanical movement. In this research work, two MTMs design approach which is resonant and non-resonant approach will be studied with the aim of achieving a frequency reconfigurable antenna using MTMs structure. Currently, frequency reconfigurable MTMs based on resonant approach is the most approach that used by the researcher. The reconfigurable design will be used Metal-Insulator-Metal (MIM) diode. Computer Simulation Technology (CST) microwave studio will be employed as the simulation tool and measurement of the result will be obtained via Vector network analyzer (VNA) and Anechoic Chamber.
PHD STUDENTS GRADUATED
RESEARCH TITLE:PATTERN RECONFIGURABLE ANTENNA USING ELECTROMAGNETIC BAND GAP STRUCTURE
Researcher: MUHAMMAD FAIZAL BIN ISMAIL (PhD Pass Viva 2020 Correction)
With the recent development of emerging technologies such as the fifth-generation networks (5G) and the internet of things (IoT), the development of reconfigurable antenna has attracted much attention as a key solution to problems relating on bandwidth, efficiency, cost reduction and the components' sizes. In addition, the reconfigurable antenna is desired to be multifunction and capable to operate with different parameter needs. The pattern reconfigurable antenna offers diversity pattern configurations and beam steering to cater the congested signal environment problem while maintaining the performances, and operating frequency and increasing the signal and data security. The pattern reconfigurable antenna using electromagnetic bandgap (EBG) structure is presented in this thesis for beam-steering configurations. Most of the previous works proposed the PIN diode on the radiating patches and caused the degradation of its performances. In this particular works, the structure offers high efficiency as the RF switches are not embedded to the radiating patches. Three types of antenna which are linear and circular polarization with pattern reconfigurable incorporated with EBG structure, the tunable polarization with pattern reconfigurable using EBG structure and dual-band pattern reconfigurable using EBG structure were designed and analysed. The EBG patches structure are located at both right and left on the same plane of radiating antenna. The EBG is designed so that its surface wave of bandgap covers the radiation of the antenna. As a result, the surface waves excited by the patch antenna are inhibited from propagation by the EBG and caused the radiation pattern of the antenna will be tilted on another side. PIN diode switching mechanism is introduced to reconfigure the EBG structure. The operating frequency of the proposed antenna is 2.45 GHz for linear and circular polarization single band antenna while 2.45 GHz and 5.8 GHz for linear polarization dual-band antenna. All proposed antenna capable to have beam shifting at three different angles (0°, +26° and - 26°). Simulated and measured results are presented, thus verifying the proposed antennas concept. Pattern reconfigurability enables wireless communication systems to avoid congested environments and save energy by redirecting signals toward intended users only.
RESEARCH TITLE:METAMATERIAL ANTENNA FOR COMPACT WIRELESS LOCAL AREA NETWORK MULTIPLE INPUT MULTIPLE OUTPUT APPLICATIONS
Researcher : Murtala Aminu Baba (PhD Graduated 2020)
Abstract
The current (4G) and future generation (5G) wireless systems require high gain multiantenna MIMO system over Single-Antenna (SA) Single-Port (SP) for their ability to provide high-speed data transmission, solutions to co-channel interference and multipath fading problems by increasing the channel capacity and enhancing the desired signal level. However, at lower frequency, conventional patch antennas are significantly large. A size reduction of antenna elements for portability and cost reduction is needed. Therefore, this research work proposes the design of four-element multiband MIMO antenna array for WLAN applications, which resonates at 2.4 GHz, 2.9 GHz and 5.8 GHz frequency bands. A complementary Split Ring Resonator (CSRR) was designed on the ground plane for size miniaturization, bandwidth improvement, compactness and isolation enhancement. The presence of the CSRR creates additional frequency bands and improves the frequency of the conventional patch antenna, which initially resonates at 5.2 GHz to 5.8 GHz. A size reduction of 96.87%, 95.41 % and 81.10 % were achieved for the 2.4 GHz, 2.9 GHz and 5.8 GHz frequency bands respectively. Similarly, an orthogonal method of antenna elements is adopted for two-port and subsequently for the four-port MIMO antenna systems with a high port-to-port isolation of less than 30 dB and 17 dB respectively. Even though, the CSRRs as the radiating elements are closer to each other at λ/4, the minimum isolation was achieved by limiting the unnecessary surface current flow that exists between the antenna elements. Nevertheless, the design is faced with low gain. To further improve the design, two-port four-element antenna arrays for MIMO applications is designed with the maximum high gain of 3.71 dBi, 2.82 dBi and 5.12 dBi, for the 2.4 GHz, 2.9 GHz and 5.8 GHz frequency bands respectively. Moreover, the proposed integration of CSRR with the antenna for MIMO antenna arrays have the advantage of multiband operation, size reduction, isolation enhancement, diversity and high gain performances. The detail calculations of the multiband MIMO antenna array system figure of merit, which include diversity gain (DG), envelope correlation coefficient (ECC) and total efficiency were presented and discussed. The results provide good diversity performances, and this shows the design is suitable for the (4G) and (5G) wireless systems with a compact size. A Computer Simulation Technology (CST) software with FR-4 substrate were used throughout the design due to its low profile & cost and ease of fabrication. The reflection & transmission coefficients, surface currents, radiation patterns and diversity parameters are presented and discussed. Lastly, fabricated prototypes are validated experimentally, and the measured results are in good agreement with simulated results.
RESEARCH TITLE: METAMATERIAL ABSORBER SWITCHABLE TO REFLECTOR
Reseacher: Mohamed Musthapa gajibo (PhD Graduated 2020)
Abstract
Metamaterials (MTMs) are materials artificially engineered by arranging artificial structural elements to achieve unusual properties or properties that do not ordinarily exist in nature. In general, Electromagnetic waves propagation is characterized by multiple directions as well as many polarization angles. These multiple direction characteristics contributes or results to complexity at the receiver’s end. However, the complexity can be reduced if not eliminated by developing MTM absorbers to absorb unwanted signals thus reducing interreference and by developing MTM/ AMC reflectors to help in guiding the transmitted electromagnetic waves towards the intended destination there by increasing directivity and portion of the received signal at the receiver’s end especially in compact scenarios. It is worth mentioning that, MTMs due to these extraordinary properties have expanded the boundaries of electromagnetic field engineering. This thesis is aimed at taking advantage of these extraordinary properties of MTMs to develop, X-band MTMs Absorbers and AMC reflectors which will help in increasing the portion of the received signals at receiver’s end. The new MTM absorbers will cater for the bulky size issues of conventional absorbers and narrow bandwidth issues associated with MTMs absorbers. Whereas the new AMC reflectors will cater for the out of phase image current and surface current propagation supported by perfect electric conductor PEC. Finally in order to improve compactness and demonstrate reconfigurability, the MTMs absorber and AMC reflectors were designed and placed side by side on the same unit cell. Reconfigurability was demonstrated using coper wire lines. The first proposed structure is based on circular ring (CR) structure, it consists of one large major circle and four smaller extended circular rings. The concept of size reduction in MTM absorbers by suppressing the resonance frequency is demonstrated at 10.70 GHz. The second structure is based on a double back-to-back split ring resonator SRR. The SRR was modified to have four copper wires as switches in order to manipulate the flow of the circulating charges. In this structure, a Dual band absorption characteristic with reconfigurability between single band (7.20GHz) and dual band (7.20GHz and 11.20GHz) absorption is demonstrated. The third structure is made up of four-square patch demarcated by a vertical bar. The charges flow paths were manipulated by connecting the individual square patch to the vertical bar with copper wires. In this structure, the concept of connecting multiple neighboring resonances to achieve a wideband absorbance is demonstrated. Almost a 100% absorption across the entire X-band region (9.00GHz to 13.00GHz) was achieved and furthermore, switchability / reconfigurability between total absorbance across X-band region and total reflection at 11.20 GHz using copper wires was also demonstrated. The structure achieved close to 80% reflection with minimum reflection of 58% at angle 600. The fourth structure comprises of two loops, the first loop which is the outer loop is made of four quarter split rings. The second loop is smaller and it is similar to the outer loop but rotated 90 degrees and consists of copper wire switch. Also, this structure achieved 100% absorption across the entire X-band region (9.00GHz to 13.00GHz) and it also demonstrated switchability / reconfigurability between total absorbance across X-band region and total reflection at 11.20 GHz using copper wires as switches. All the proposed designs were tested for angles 00 to 600 in which almost all of them performed excellently with minimum absorption rate of close to 80% and reflection rate of close to 75%. Additionally, switchability using copper wires was demonstrated in some of the structures.
RESEARCH TITLE: 3D PRINTING MICROWAVE BUTLER MATRIX FOR 5G APPLICATION
Researcher: Muataz Almashehe (Co Supv PhD Graduated 2020)
Abstract
The demand for high speed data and information exchange urge on a better communication service. The existing services may not able to satisfy the increasing data volume with increasing number of users. The current technology may suffer from congestion and spectrum shortage issue. Thus, higher frequency spectrum is introduced for wireless cellular system. Millimetre wave frequency band is one of interest in future communication technology. However, at high frequencies, a higher propagation loss is expected. With smaller antenna element at millimetre wave band, more elements can be packed creating arrays making beamforming possible by controlling the signal phase. Beamforming makes the concentration of signal in certain direction is possible, thus maximizing the received signal level. The Butler matrix beamforming network is adopted in this work due to its simplicity with capability to form high gain-narrow beam signal by various phase shift characteristics at the output. However, at millimetre wave the massive network can introduce significant losses on the components as well as the interconnections. Therefore, this work proposes a new and low loss waveguide-based structure where the signal is governed within the walls. Components of Butler matrix beamforming circuit are designed using waveguide structure before integrated with the antenna. The components are the coupler, crossover, and phase shifter while the antenna is basically a very directive waveguide slots antenna. The structures are simulated using CST microwave software before fabricated using 3D printer and measured using standard VNA. All the components with the antenna are metal printed using DMLM and SLM 3D printing techniques. 3D printing technology is used which gives more flexibility in realizing the design parts from low cost and environmentally friendly with minimum chemical waste. The proposed Butler matrix has measured reflection and isolation coefficients of less than -10 dB, with transmission coefficients of range between -7 to -9 dB. The proposed Butler matrix has measured phase shifts of range from -42.02° to 42.02° and -130.95° to 133.3° in the x-y plane. The proposed antenna beamforming has measured highest gain of 15.21 dB and measured scanning angels of range from -23.86° to 52.47° in the x-y plane. Overall, the proposed Butler matrix and the proposed antenna beamforming have great potential for millimetre wave wireless systems applications.
RESEARCH TITLE: RECONFIGURABLE DUAL BAND ANTENNA USING ELECTROMAGNETIC BAND GAP UNIT CELLS
RESEARCHER: RAIMI DEWAN (PhD Graduated 2019)
Abstract:
Reconfigurable antenna is an antenna that is can change its frequency, radiation pattern, beam, and polarization. Conventionally, reconfigurable mechanism is implemented directly to the antenna radiating part and transmission feeding network. This can cause performance degradation such as gain reduction of the antenna. Apart from that, EBG that typically use for reconfigurable mechanism usually high in number unit cells, complicated design and does not perform for frequency and pattern reconfigurability. This research incorporates Electromagnetic Band Gap (EBG) unit cells to dual band array antenna which operates at 2.4 GHz and 5.8 GHz to achieve frequency and pattern reconfigurability. The antenna array with EBG is 78% smaller than similar past design. In frequency reconfigurability, the EBG successfully realized a dual band reconfigurable antenna which can operate at both band, low band, and high band alternately. In both bands, the simulated realized gain at 2.4 GHz and 5.8 GHz is 5.683 dBi and 7.271 dBi respectively. The simulated realized gain at low band and high band frequency reconfiguration is 6.268 dBi and 7.833 dBi respectively. The corresponding gain of the reconfigurable frequency is comparable to the simulated realized gain of the standalone array antenna of 6.214 dBi and 8.461 dBi at 2.4 GHz and 5.8 GHz respectively. In pattern reconfigurability, the pattern of the antenna is reconfigured at the lower frequency of 2.4 GHz while at the upper frequency of 5.8 GHz is remain not reconfigured. With active EBG, the simulated antenna able to operate at both band with no pattern shift, at lower band with pattern shift of 1o, 29o and 345o. Additionally, the measured pattern shift with active EBG is 0o, 30o and 330o. Pattern reconfigurability antenna also achieve frequency reconfigurability by attenuating the gain at the specific operating frequency. EBG successfully realized a dual band array antenna with frequency and pattern reconfigurability using minimum number of EBG unit cells.
Journal with Impact Factor
1.Raimi Dewan, M.K.A. Rahim, Mohamed Himdi, M.R. Hamid, H.A. Majid and M.E. Jalil, “Multiband Frequency Reconfigurable Antenna Using Metamaterial Structure of Electromagnetic Band Gap” Applied Physics A, Vol. 123, pp 1-7, 2016. https://doi.org/10.1007/s00339-016-0643-1. (Q2, IF: 1.604)
2.Raimi Dewan, M.K.A. Rahim, M.R. Hamid, M.F.M. Yusoff, N.A. Samsuri, N.A. Murad, and K. Kamardin, “Artificial Magnetic conductor for various antenna applications: An Overview” International RF and Microwave Computer-Aided Engineering, p. e21105–n/a, 2017. https://doi.org/10.1002/mmce.21105. (Q3, IF= 1.306)
3.Raimi Dewan, M.K.A. Rahim, M.R. Hamid, H.A. Majid, M.F.M. Yusoff and M.E. Jalil, “Reconfigurable Antenna Using Capacitive Loading to Artificial Magnetic Conductor (AMC)” Microwave and Optical Technology Letters, Vol. 58, pp. 2422-2429, 2016. https://doi.org/10.1002/mop.30062. (Q4, IF: 0.948)
Indexed Journal
1. Raimi Dewan, M.K.A Rahim, M.R. Hamid, Mohamed Himdi, H.A. Majid and N.A. Samsuri “HIS-EBG Unit cells for Pattern and Frequency Reconfigurable Dual Band Array Antenna” Progress in Electromagnetic Research M, Vol. 76, pp. 123-132, 2018. https://doi.org/10.2528/PIERM18090202. (Indexed by SCOPUS)
2. Raimi Dewan, M.K.A. Rahim, M.R. Hamid and M.E. Jalil, “Mutual coupling reduction in antenna array using metamaterial electromagnetic band gap (EBG) on double substrate layers” Telecommunication Computing Electronics and Control, Vol. 15, pp. 799-804, 2017. https://doi.org/10.12928/TELKOMNIKA.v15i2.6123. (Indexed by SCOPUS)
3. Raimi Dewan, M.K.A. Rahim, M.R. Hamid, M.F.M. Yusoff, H.A. Majid, and B.A.F. Esmail “Dual Band to Wideband Pentagon-shaped Patch Antenna with Frequency Reconfigurability using EBGs” International Journal of Electrical and Computer Engineering (IJECE), Vol. 8, pp. 2557-2563, 2018. https://doi.org/ 10.11591/ijece.v8i4.pp2557-2563. (Indexed by SCOPUS)
4. Raimi Dewan, Mohamad Kamal A Rahim, Rijal Hamid, M.H. Mokhtar and M.F.M. Yusoff, "Effect of CPW Edges Chamfering to The Performance of Ultra-Wideband Antenna" Vol. 77, pp. 79-84, Jurnal Teknologi, 2015. https://doi.org/10.11113/jt.v77.6287. (Indexed by SCOPUS)
Non-indexed Journal
1. R. Dewan, M.K.A. Rahim, M.R. Hamid, and M.F.M. Yusoff “Analysis of Wideband Antenna Performance Over Dual Band Artificial Magnetic Conductor (AMC) Ground Plane” Technology and Engineering Review and Research Advances I, Applied Mechanics and Materials, Vol. 735, pp. 273-277, 2015. https://doi.org/10.4028/www.scientific.net/AMM.735.273.
Indexed Conference Proceeding
1. R. Dewan, M.K.A. Rahim, Mohamed Himdi, M.R. Hamid, and N.A. Samsuri, “Frequency Reconfigurability Array Antenna with Electromagnetic Band Gap (EBG) Cells” Asia Pacific Microwave Conference, pp. 747-750 2017. https://doi.org/10.1109/APMC.2017.8251555 (Indexed by SCOPUS)
2. Raimi Dewan and Mohamad Kamal A. Rahim, "Antenna Performance Enhancement with Artificial Magnetic Conductor (AMC)" IEEE International Conference on Antenna Measurements & Applications, pp. 1-4, 2015. https://doi.org/ 10.1109/CAMA.2015.7428141. (Indexed by SCO)
3. R. Dewan, M.K.A. Rahim, M.R. Hamid and H.A. Majid “Ultra-wideband Antenna with Tunable Artificial Magnetic Conductor” International Symposium on Antennas and Propagation, pp 105-106, 2014. https://doi.org/ 10.1109/ISANP.2014.7026552. (Indexed by SCOPUS)
4. R. Dewan, M.K.A. Rahim, M.R. Hamid, N.A. Samsuri, and B.D. Bala “Analysis of Triple Band Artificial Magnetic Conductor (AMC) Band Condition to Wideband Antenna Performance” Asia-Pacific Microwave Conference, pp. 167-170, 2014. https://doi.org/10.1109/APACE. 2014.7043770 (Indexed by SCOPUS)
5. Raimi Dewan and Mohamad Kamal A. Rahim, “Antenna Incorporating Artificial Magnetic Conductor” EuMW conference, 2017. (Indexed by SCOPUS)
6. R. Dewan, M.K.A. Rahim, M.R. Hamid and H.A. Majid, “Multiband Reconfigurable Antenna Using EBG unit cells”, IEEE Asia-Pacific Conference on Applied Electromagnetics, 2016. https://doi.org/10.1109/APACE.2016.7916465. (Indexed by SCOPUS)
Non-indexed Conference Proceeding
1. R. Dewan, M.K.A. Rahim, M.R. Hamid and M.F.M. Yusoff “Wideband Antenna Performance Over Dual Band Artificial Magnetic Conductor (AMC) ground Plane”, International Graduate Conference on Engineering Science & Humanity, pp1-2,2014. https://doi.org/10.4028/www.scientific.net/AMM. 735.273
2. Raimi Dewan, M.K.A. Rahim, Mohamed Himdi, M.R. Hamid, and M.E. Jalil, “Dual Band Frequency Reconfigurable Array Antenna Using Metamaterial” International Conference on Metamaterials, Photonic Crystals and Plasmonics, 2017
3. Raimi Dewan, M.K.A. Rahim, Mohamed Himdi, M.R. Hamid and N.A. Samsuri, “Metamaterial-HIS for Pattern Reconfigurable Multband Array Antenna” International Conference on Metamaterials, Photonic Crystals and Plasmonics, 2017.
4. Raimi Dewan, M.K.A. Rahim, M.R. Hamid, M.E. Jalil, and H.A. Majid, “Frequency Reconfigurable Antenna with Metamaterial Electromagnetic Band Gap (EBG) Structures” International Conference in Metamaterials, Photonic Crystals and Plasmonics, 2016.
5. R. Dewan, M.K.A. Rahim, M.R. Hamid, H.A. Majid, M.F.M. Yusoff and M.E. Jalil, “Reconfigurable Antenna Using Capacitive Tuning Metamaterial of Artificial Magnetic Conductor” International Conference on Metamaterials, Photonic Crystals and Plasmonics, 2015.
RESEARCH TITLE: COMPACT MEANDER LINE TELEMETRY ANTENNA WITH INTERFERENCE REDUCTION TOWARDS PACEMAKER APPLICATION
Researcher: NOOR HAFIZAH BINTI SULAIMAN (Co Supv Phd Graduated 2019)
Abstract
The demand for health technology is increasing rapidly especially in telemetry applications which use implanted antennas for efficient monitoring of the patients. Size of the telemetry antenna becomes main issue in the design of implantable devices. Furthermore, maintaining the good performance of implantable antenna in different environments is a challenging task. Therefore, the research project presents a design of telemetry antenna to be used in pacemaker applications in the Medical Implant Communication Services (MICS) band (401 MHz - 406 MHz) focusing both on the design and performance optimization. The proposed compact meander line telemetry antenna (CMLTA) provided close agreement between measured and simulated results with advantages of easy fabrication, low cost, light weight and a 133 MHz bandwidth. In the research project, the specific absorption rate (SAR) measurements are also carried out using a homogenous liquid phantom developed for MICS frequency band. The material characterizations of the developed phantom are performed in order to verify the dielectric properties. The SAR analysis is performed using 1 W input power, where the maximum 1g and 10g average SAR satisfy the Institute of Electrical and Electronics Engineers (IEEE) standard safety guidelines. Finally, experimental validations are also performed to observe the antenna effect in the body with the pacemaker by placing the CMLTA in beef representing human body. The experiments are carried out under various conditions such as variable input power, distance variation, and in the presence of external active devices (sources) such as mobile phone and 2.4 GHz external antenna. , it is observed that the presence of CMLTA does not have any effect on the timing of pulses generated by artificial pacemaker. Therefore, it can be concluded that the proposed CMLTA can be employed for significant interference reduction towards pacemaker application.
RESEARCH TITLE: FILTENNA DESIGN FOR SELECTIVITY ENHANCEMENT FOR WIRELESS APPLICATION
Researcher: Ali Nyangwarimam (CoSupv PhD - Graduated 2017)
Abstract
This project presents filters and filtennas design with selectivity enhancement for modern communication systems. Two filters namely Filter A and Filter B and two filtennas namely Filtenna A and Filtenna B have been designed to overcome a few draw backs such as decrease in the peak gain, poor selectivity, increase in feeding area and structure complexity of the existing filters and filtennas. Firstly an improved technique for creating sharp selectivity of a T-shaped stub bandpass filter (Filter A) is designed. The T-shaped stub is loaded with vertical resonators to produce good selectivity at both edges of the passband at 3.6 GHz. The advantage of this filter is the potential ability to adjust the center frequency and the bandwidth to suite the system demands. Secondly, a novel and compact second order Chebyshev bandpass filter (Filter B) with sharp selectivity is designed to operate at 5.8 GHz.The sharp selectivity is obtained by using U-shaped resonators and Defected Ground Structure which are responsible for the rejection at the higher and lower band edge respectively. The advantage of this design is size compactness. About 56% area reduction is achieved over the second order Hairpin bandpass filter. Thirdly, the Tshaped stub bandpass filter is synthesized with a microstrip patch antenna to form a T-shaped stub fed filtenna (Filtenna A) with enhanced selectivity. The advantage of this design is that it maintains the same bandwidth as the conventional patch antenna with enhanced gain and good out of band suppression. The fourth design involves the synthesis of the second order Chebyshev designed filter with a U-shaped patch (Filtenna B). The designed filtenna operates at 5.8 GHz and has sharp selectivity as no degradation of the peak gain. The superiority of the proposed designed over the conventional patch antenna is verified by a numerous 99 % decrease in the out of band suppressions and a 11.86 % increase in the gain performances. The designed filtennas address the limitations faced by existing filtennas and can be used in WLAN and WiMAX applications. All designed structures were simulated using CST Microwave Studio and validated through fabrication and measurement of the prototypes
RESEARCH TITLE: RECONFIGURABLE ANTENNA WITH POLARIZATION AND PATTERN DIVERSITIES FOR LIMITED SPACE MIMO SYSTEMS
Researcher : MUHAMAD NASRUN OSMAN (PHD - GRADUATED 2016)
Abstract:
Wireless communication undergoes a dramatically change in recent years. More and more people are using modern communication services, thus increasing the need for more capacity in transmission. One of the methods that able to meet the demands is the use of multiple antennas at both link ends known as multiple input multiple output (MIMO) system. However, for the space limited MIMO systems, it is relatively difficult to accomplish good performance by using conventional antennas. Therefore, to further improve the performance offered by MIMO, the polarization reconfigurable antennas (PRAs) can be adopted. The diversity in polarization can be exploited to increase the channel capacity. Moreover, the use of PRAs also can provide savings in term of space and cost by arranging orthogonal polarized together instead of two physically space separation antennas. Here, single and dual port PRAs are proposed. Two techniques deployed to achieve the PRAs are slits perturbation (switches on the radiating patch) and alteration of the feeding network (switches on the ground plane). Switching mechanism (ideal and PIN diode) is introduced to reconfigure the polarization between left-hand circular polarizations, right-hand circular polarizations, or linear polarization, operating at wireless local area network frequency band (2.4 – 2.5 GHz). Furthermore, by exploiting the odd and even mode of the coplanar waveguide structure, dual port PRAs is realized with the ability to produce orthogonal linear (LP) and circular polarization (CP) modes simultaneously. Good measured port isolation (S21) of -16.3 dB and -19 dB are obtained at the frequency of 2.45 GHz for configuration A1 (orthogonal LP) and A2 (orthogonal CP), respectively. The proposed PRAs are tested in the 2 x 2 MIMO indoor environments to validate it performances by using scalar power correlation method when being applied as a receiver in both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Channel capacity improvement has been achieved for spatial diversity (92.9% for LOS and 185.9% for NLOS) and polarization diversity (40.7% for LOS and 57.9% for NLOS). The proposed antenna is highly potential to be adopted to enhance the performance of the MIMO systems, especially in dealing with multipath environment and space limited application
Jurnal Publications
1.Mohamed Nasrun Osman, Mohamad Kamal A. Rahim, Mohd fairus Mohd Yusof, Mohd Rijal hamid, Huda A Majid and Muzammil Jusoh 'Polarization Reconfigurable Antenna through Switchable CPW feeding structure', Jurnal teknologi, Vol. 77, No 10, pp 107-112, 2015 (SCOPUS)
2.Mohamad Nasrun.Osman, Mohamad Kamal.A.Rahim, Peter Gardner, Mohamad Rijal Hamid, Mohd Fairus Mohd Yusof and Huda A.Majid, 'An Electronically Reconfigurable Patch Antenna Design for Polarization Diversity with Fixed Resonant Frequency ' Radio Engineering, Vol 24, No 1, pp 45- 53, April 2015 (ISI/SCOPUS)
3.M.N.Osman, M.K.A.Rahim, M.R.Hamid and M.F.M.Yusof, 'Compact Dual-Port Polarization Reconfigurable Antenna with High Isolations for MIMO Application' Antenna Wireless Propagation letter, Vol 15, pp 456 - 456 Feb 2016 (ISI/SCOPUS)
4.MN Osman, MKA Rahim, MR Hamid, MFM Yusoff, MZAA Aziz, M Jusoh ‘Indoor Channel Capacity Measurement of 2 x 2 MIMO Polarization Diversity Antenna’, Indonesian Journal of Electrical Engineering and Computer Science (IJEECS), Vol. 10 No 3, pp 1196- 1202, June 2018 (SCOPUS)
Proceeding Publications
1.Mohamed Nasrun Osman, Mohamad Kamal A.Rahim, Mohd Rijal Hamid, Mohd Fairus Mohd Yusof and Huda A Majid, "Circular patch antenna design with switchable polarization" 2013 IEEE International RF and Microwave Conference (RFM2013), Bayview Beach Resort, Penang, 9-11 Dec 2013
2.MN Osman, MKA Rahim, MFM Yusoff, MR Hamid, NA Murad, NA Samsuri, "Polarization reconfigurable circular patch antenna with fixed operating frequency", 8th European Conference on Antenna and propagation (Eucap 2014),pp 2741-2743, Den Haag, Holland, 2014
3.Mohamed Nasrun Osman, Mohamad Kamal A Rahim, Mohd Rijal Hamid, Mohd Fairus Mohd Yusof and Huda A.Majid, Polarization Reconfigurability Patch Antenna with improved Axial Ratio Bandwidth', 2014 IEEE Asia-Pacific Conference on Applied Electromagnetic (APACE 2014), Johor Bahru Johor, 8-9 Dec 2014
4.M.N.Osman, M. K. A. Rahim, M.F.M.Yusof, M.R.Hamid and H.A.Majid, 'Polarization Reconfigurable Patch Antenna through modification of feeding network', International Symposium on Antennas and Propagation (ISAP 2014),Kaohsiung, Taiwan, 2-5 Dec 2014
MN 5.M.N.Osman, MKA Rahim, MFM Yusof, MR Hamid and M. Jusoh, ‘Dual-port polarization reconfigurable antenna using compact CPW slotline feeding structure for space-limited MIMO application Dual-port polarization reconfigurable antenna using compact CPW slotline feeding structure for space-limited MIMO application', 2015 IEEE Conference on Antenna Measurements and Application’ (CAMA 2015), Chiangmai, Thailand, Nov
RESEARCH TITLE: DESIGN AND DEVELOPMENT OF METAMATERIAL ABSORBER AT X BAND FREQUENCY
Researcher: OSMAN BIN AYOP (PhD - GRADUATED 2016)
Abstract:
This research proposes the design of microwave absorber based on metamaterial structure working at X-band frequency range. New structures of metamaterial are proposed to work at narrow band, multi-band, and wideband operating frequency. The research involves the critical analysis of each structures based on their reflectance, transmittance and absorbing performance from the interaction of incident electromagnetic waves with the designed structures. A perfect metamaterial absorber is obtained if the reflectance and transmittance values go to zero indicate that the structure is efficiently attenuates the incident electromagnetic waves through the structure. The absorbance value is then lead up to the maximum value (1) indicates that the 100% absorbance is achieved. These results obtained under a condition that the designed structures have the same surface impedance as the free space impedance during resonance. To achieve this impedance value, the complex frequency dependent effective permittivity and the effective permeability of the structure are the same value. In addition, the imaginary part of refractive index of the structures must be as high as possible to maximize the absorption. In the end of the research, new structures of metamaterial absorber will be designed, simulated, fabricated, measured and analysed for X-band frequency.
Jurnal Publications
1.Osman Ayop, Mohamad Kamal A Rahim, Noor Asniza Murad, Huda A Majid, 'Metamaterial Absorber based on circular ring structure with and without copper lines', Applied Physics A, Volume 117, Issue 2, pp 651-656, Nov 2014 (ISI/SCOPUS)
2.Osman Ayop, Mohamad K.A.Rahim, Noor A. Murad, Noor A Samsuri and Raimi Dewan, " Triple band circular ring-shaped metamaterial absorber for X-band applications' Progress in Electromagnetic Research M (PIERM), Vol 39, pp-65-75, 2014 (SCOPUS)
3.Osman Ayop, Mohamad Kamal A. Rahim and Noor Asniza Murad, 'Polarization-Independent Metamaterial Absorber for Single band and Multi-band frequency', Jurnal teknologi, Vol. 77, No 10, pp 99-106, 2015 (SCOPUS)
4.Osman Ayop, Mohamad Kamal A Rahim, Noor Asniza Murad and Noor Asmawati Samsuri, ' Dual-resonant polarization-independent and wide-angle metamaterial absorber in X-band frequency', Applied Physics A , 2016 (ISI/SCOPUS)
5.Osman Ayop, Mohamad Kamal A Rahim, Noor Asniza Murad, Noor Asmawati Samsuri, 'Wideband polarization-insensitive metamaterial absorber with perfect dual resonances', Applied Physics A 2016 (ISI/SCOPUS)
6.O Ayop, MKA Rahim, NA Murad, NA Samsuri, F Zubir, HA Majid, 'Dual-band metamaterial perfect absorber with nearly polarization-independent' Applied Physics A, Vol 123 (1), 63, Jan 2017 (ISI/SCOPUS)
Proceeding Publications
1.Osman Ayop, Mohamad Kamal A. Rahim, Noor Asniza Murad, “Wide angle and polarization insensitive circular ring metamterial absorber at 10 GHz”, 2013 International Symposium on Antennas and Propagation (ISAP 2013), Nanjing China, Oct. 23-25, 2013
2.Osman Ayop, Mohamad Kamal A.Rahim, Noor Asniza Murad, "Double layer circular ring metamaterial absorber for dual directional application at 10 GHz" 2013 IEEE International RF and Microwave Conference (RFM2013), Bayview Beach Resort, Penang, 9-11 Dec 2013
3.O Ayop, MKA Rahim, NA Murad, NA Samsuri, "Dual band polarization insensitive and wide angle circular ring metamaterial absorber", 8th European Conference on Antenna and propagation (Eucap 2014),pp 955-957, Den Haag, Holland, 2014
4.Osman Ayop, Mohamad Kamal A Rahim and Noor Asniza Murad, 'Polarization Insensitive and wide operating angle metamaterial absorber at X-band', 2014 IEEE Asia-Pacific Conference on Applied Electromagnetic (APACE 2014), Johor Bahru Johor, 8-9 Dec 2014
5.O.Ayop, M. K. A. Rahim, N.A. Murad and N.A Samsuri, 'Dual band Polarization Insensitive Metamaetrial Absorber in X-band', International Symposium on Antennas and Propagation (ISAP 2014),Kaohsiung, Taiwan, 2-5 Dec 2014
6.O.Ayop, M. K. A. Rahim, N.A. Murad and N.A Samsuri, ‘Dual resonance circular ring-shaped metamaterial absorber with wide operating angle', International Symposium on Antennas and Propagation (ISAP 2015),Hobart, Tasmania, 9-12 Nov 2015
RESEARCH TITLE : MIMO CHANNEL CHARACTERIZATION WITH POLARIZATION DIVERSITY
Researcher: MOHD ZOINOL ABIDIN ABD AZIZ (PhD - GRADUATED 2015)
Abstract
In recent years, the remarkable growth of wireless communication systems mainly in data transmission such as huge files, video and voice has increased the demand of higher data transfer rate. Thus, lead to the demand of higher channel capacity. MIMO (multiple input multiple output) systems which allow multiple parallel channel to be transmitted or received simultaneously is considered a breakthrough in solving the problem. In MIMO, the channel capacity is increased without additional transmit power or bandwidth. Furthermore, the technique called diversity has been proven to increase the channel capacity in MIMO systems. This project focus on the development of front end 4 X 4 wireless MIMO systems at 2.4GHz. The double stage diversity which combined polarization diversity and spatial diversity have been employed. X-polarized antenna with single port technique has been design to produce X linear polarization wave at 2.4GHz frequency. The design simulation and fabrication was done by using CST software and chemical etching technique. The configuration of typical, spatial diversity and polarization diversity has been set up and measured in indoor environment. Channel capacity for spatial and polarization diversity has improved up to 14.4% and 27.9% respectively. Meanwhile, X-polarized (double stage diversity) channel capacity has improved up to 17.75%.
Jurnal Publications
1.M.Z.A. Abd. Aziz, M.S.R. Mohd Shah, M.K. Suidi and M.K.A Rahim ‘Dual Polarization Single Port Inset Feed Microstrip Patch Antenna’, Jurnal of Telecommunication, Electronic and Computer Engineering, vol 3,no 1 pp 15-20, Jan. - June 2011 (SCOPUS)
2.M.Z.A. Abd. Aziz, Z. Daud, M.K. Suidi and M.K.A Rahim ‘Analysis of Indoor MIMO Channel Capacity Using Spatial Diversity Technique’, Jurnal of Telecommunication, Electronic and Computer Engineering, ,Vol 2, No 2, pp 55 - 59, 2010 (SCOPUS)
3.Mohd Zoinol Abidin Avdul Aziz and Mohamad Kamal A Rahim, 'Wireless MIMO Channel Capacity Using Double Stage Diversity Technique', Wireless personal Communication, Vol 85, Issue 4., pp 2067-2081, December 2015 (ISI)
Proceeding Publications
1.M.S.R., Mohd Shah, M.K. Suidi, M.Z.A. Abd Aziz, M.R. Che Rose, M.F.A. kadir, A.S. Jaafar, M.Sidek., M.K.A Rahim, ‘Dual Polarization Inset-Fed microstrip patch antenna’, Proceedings 2008 8th International conference on Intelligent Transport System Telecommunications (ITST 2008), 22-24 October 2008, Phuket, Thailand
2.M.S.R., Mohd Shah, M.K. Suidi, M.Z.A. Abd Aziz, M.R. Che Rose, M.F.A. Kadir, A.S. Jaafar, M.Sidek., M.K.A Rahim, ‘Dual Polarization microstrip patch array antenna’, 2008 International Sysmposium on Telecommunications (IST 2008), 27 – 28 August 2008, Tehran Iran
3.M.S.R., Mohd Shah, M.K. Suidi, M.Z.A. Abd Aziz, M.R. Che Rose, M.F.A. Kadir, A.S. Jaafar, M.Sidek., M.K.A Rahim, ‘Design of 1x2, 1x4, and 2x4 dual polarization microstrip array antenna, ,‘Proceeding of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics (NCTT-MCP 2008)’, -28 August 2008, Putrajaya, Malaysia
4.M.F.A. Kadir, M.K. Suidi, M.Z.A.A. Aziz, M.R.C. Rose, M.S.R.M Shah, D. Misman, M.K.A. Rahim, ‘Polarization Diversity in wireless MIMO systems,‘Proceeding of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics (NCTT-MCP 2008)’, -28 August 2008, Putrajaya, Malaysia
5.M.R.C. Rose, M.K.Suidi, M.Z.A.A Aziz, M.F.A.Kadir, D. Misman, MS.R.M. Shah, M.K.A.Rahim, ‘Analysis of angle diversity in MIMO channel’, Proceeding of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics (NCTT-MCP 2008), 26-28 August 2008, Putrajaya, Malaysia
6.M.S.R Mohd Shah, M.F.Abd Kadir, M. Disman M.K.Suidi, M.Z.A. Abd Aziz, I.M. Ibrahim, M.K.A.Rahim , “Dual Polarization Inset feed Microstrip Patch antenna”, International Symposium on Antennas and Propagation (ISAP 2008), Taiwan, 27-30 October 2008
7.M.F.Abd Kadir, M.K.Suidi, M.Z.A. Abd Aziz, M.K.A.Rahim, “Wireless Beamforming With Polarization Diversity”, International Symposium on Antennas and Propagation (ISAP 2008), Taiwan, 27-30 October 2008
8.M.S.R Mohd Shah, M.K.Suidi, M.Z.A.Abdul Aziz, M.F. Abd Kadir, M.K.A. Rahim, “Dual Polarization Microstrip Patch Array antenna for WLAN application”, 3rd Europen Conference on Antenna and propagation (Eucap 2009), Berlin, 23 – 27 March 2009
9.Z.Daud, M.Z.A. Abd Aziz, M.K.Suidi, M.F. Abdul Fadir and M. K. A Rahim, “Wireless MIMO Channel Capacity Analysis Based on Multiple Spatial Diversity for Indoor Propagation”, 5th Europen Conference on Antenna and propagation (Eucap 2011), Rome, Italy, 11 – 15 April 2011
RESEARCH TITLE: TEXTILE ARTIFICIAL MAGNETIC CONDUCTOR WAVEGUIDE SHEET FOR TRANSMISSION ENHANCEMENT BETWEEN ANTENNAS FOR BODY CENTRIC COMMUNICATION
Researcher: KAMILIA KAMARDIN (PhD- GRADUATED 2014)
Abstract:
The rising interest in body centric communication is due to the need of a more reliable short-range wireless communication within a human body. Wireless Body Area Network (WBAN) associates with wearable devices that offers networking within human body which allows new conveniences and services. However, wearable antennas suffer performance degradation due to the distinct properties of human body itself. Radiation characteristics and input impedance of wearable antennas will be distorted when placed on human body. In addition, the radiation that goes towards human body is a major health concern. The presence of human body also introduces high transmission loss between on-body antennas. Good transmission between antennas are crucial for an efficient wireless networking system within human body. High transmission loss can lead to a non-reliable system that is undesired. This study proposes an artificial magnetic conductor (AMC) waveguide sheet that improves wireless on-body transmission. The sheet-like waveguide provides an independent transmission path which can reduce all distortions caused by human body. The proposed AMC waveguide sheet consists of textile substrate with radiating patches and ground plane made of conductive fabric. The flexibility of textile material make it suitable for wearable communications. The transmission characteristics between antennas was studied rigorously in this work. Compared to S21 transmission for antennas in free space, above metal plate, above dielectrics and on human body, the transmission between two antennas are greatly improved with the presence of AMC sheet. Transmission loss between the antennas have been significantly reduced apart from minimizing the radiation towards human body. In addition, body centric measurements were also investigated which includes bending, wetness, presence of human body and SAR. Different orientation and placement of the antennas were considered. The textile-based AMC waveguide sheet will act as a new approach for an efficient wearable wireless body-centric communications.
Jurnal Publications
1.Kamilia Kamardin, Mohamad K. A. Rahim, Noor A. Samsuri, Mohd E Jalil, and Izni H. Idris, ‘Textile AMC waveguide jacket for on body transmission enhancement’, Progress In Electromagnetics Research B, Vol. 54, 45-68, 2013 (Scopus)
2.Kamilia Kamardin, Mohamad K. A. Rahim, Noor A. Samsuri, Mohd E Jalil, Izni H. Idris and M.F. Abdul Majid, ‘Textile AMC waveguide sheet with wire dipoles for body centric communication’, Jurnal teknologi, Vol. 64, No 3, pp 29-35, 2013 (Scopus)
3.Kamilia Kamardin, Mohamad Kamal A Rahim, Noor Asmawati samsuri, Transmission Enhancement using Textile Artificial Magnetic Conductor with Co-planar Waveguide Monopole Antenna' Microwave optical technology letter,Vol 57, No 1, pp 197-200, Jan 2015 (ISI)
4.K.Kamardin, M.K.A.Rahim, P.S.Hall and N.A.Samsuri, 'Vertical and Horizontal transmission enhancement between antennas using textile artificial magnetic conductor waveguide sheet', Electronics Letter, Volume 51, Issue 9, , pp 671-673, April 2015, (ISI)
5.Kamilia KAMARDIN, Mohamad Kamal A. RAHIM, Peter S. HALL, Noor Asmawati SAMSURI, Mohd Ezwan JALIL, Mohd Fareq ABD MALEK, ' Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements', Radio Engineering Jurnal, vol 24, No 3, pp 729-738, September 2015.(ISI)
6.Kamilia Kamardin, Mohamad Kamal A Rahim, Peter S. Hall, Noor Asmawati Samsuri, Tarik Abdul latef and Mohammad Habib Ullah , ‘Textile AMC for transmission enhancement between antennas under bending and wetness measurement’, Applied Physics A, April 2016 (ISI)
7.K. Kamardin, M.K.A.Rahim, P.S.Hall, N.A Samsuri, T.A Latif, M.H.Ullah, ‘Planar textile antennas with AMC for body centric communications’, Applied Physics A, 2016 (ISI)
8.Kamilia Kamardin, Mohamad Kamal A.Rahim, Noor Asmawati Samsuri, Mohd Ezwan Jalil, Siti Sophiayti Yuhania, Mohd Nazri Kama, Othman Mohd Yusof, 'A parametric study of Textile Artificial magnetic Conductor with wire dipole', ARPN Journal of Engineering and Sciences, Vol 11, No 12, pp 7888 - 7893, June 2016 (SCOPUS)
9.Kamilia Kamardin, Mohamad Kamal A.Rahim, Noor Asmawati Samsuri, Mohd Ezwan Jalil, Salwani Mohd Daud, Suriani Mohd Sam, Noor Azurati Ahmad, 'Textile diamond dipole for body centric communications at 2.4 GHz and 5.8 GHz",ARPN Journal of Engineering and Sciences, Vol 11, No 12, pp 7877 - 7882, June 2016 (SCOPUS)
Proceeding Publication
1.Kamilia Kamardin, Mohamad Kamal A.Rahim, Osman Ayop, “Compact Multisize Circular Patch EBG structure for wide stopband circuits”, Indonesia-Malaysia Microwave Antenna Conference (immac 2010), Jakarta,Indonesia 11-12 June, 2010
2.K.Kamardin, M.K.A.Rahim, P.S.Hall, N.A.Samsuri and N.A Elias, "Printed Dipole with slot EBG Structures with Artifiial Magnetic Conductor and band Notch Behaviour", 2011 IEEE International RF and Microwave Conference, Seremban, N. Sembilan, 12-14 Dec 2011
3.Kamardin, K.; Rahim, M.K.A.; Hall, P.S.; Samsuri, N.A.; Jalil, M.E.; Anuar, M.Z., "Textile waveguide sheet with Artificial Magnetic Conductor structures for body centric wireless communication," Applied Electromagnetics (APACE), 2012 IEEE Asia-Pacific Conference on , vol., no., pp.257,261, 11-13 Dec. 2012
4.Kamilia Kamardin, Mohamad Kamal A.Rahim, Peter S Hall, Noor Asmawati Samsuri, Mohd Ezwan Jalil, Osman Ayop, "Textile Artificial Magnetic Conductor Waveguide sheet with monopole Antennas for body centric Communication", 7th European Conference on Antenna and propagation (Eucap 2013), Gothenburg, Sweden, 8 – 12 April 2013
5.Kamilia Kamardin, Mohamad Kamal A.Rahim, Noor Asmawati Samsuri and Mohd Ezwan Jalil, "Textile waveguide sheet with AMC sttructures for Transmission Enhancement between wire dipoles antenna" 2013 IEEE Antenna and Propagation Symposium (APS 2013), Orlando Florida, USA, 7-13 July 2013
RESEARCH TITLE: FREQUENCY RECONFIGURABLE MICROSTRIP SLOT ANTENNA
Researcher:HUDA A. MAJID (PhD- GRADUATED 2013)
Abstract:
Cognitive radio system needs a wideband antenna for spectrum sensing and a narrowband reconfigurable antenna for communication link. Presented here are frequency reconfigurable antennas which are capable for narrowband to narrowband reconfiguration and wideband to narrowband reconfiguration. These concepts are introduced to give high flexibility to a wireless terminal to operate in different bands. The proposed antennas are potentially useful for future wireless communication system such as cognitive radio. Four novel frequency reconfigurable antennas are presented and discussed. Microstrip slot technique is used as a basis for all design of the narrowband reconfigurable antennas. First, a frequency reconfigurable slot antenna is proposed to have a capability for narrowband to narrowband reconfiguration. The antenna is capable to reconfigure up to six different narrowbands from 2.2 GHz to 4.75 GHz. Second, a frequency reconfigurable slot integrated with patch antenna is proposed. The proposed antenna is capable to reconfigure into nine different narrowbands from 1.98 GHz to 3.41 GHz. Here, the omni-directional radiation pattern is introduced in slot mode while directional radiation pattern is obtained in patch mode. The third designed antenna is a monopole wideband antenna integrated with frequency reconfigurable slot antenna. This concepts offer wideband to narrowband reconfigurablility. The significant advantage of this approach is, it offers pre-filtering for the front end cognitive radio system, which reduces the interference level at the receiver. The proposed antenna has the capability to reconfigure between wideband (2 GHz - 6 GHz) and three different narrowbands from 3.02 GHz to 4.56 GHz. Finally, a frequency reconfigurable slot antenna with added function of tuneable radiation pattern is also been presented. The antenna has the ability to reconfigure three different narrowbands from 1.75 GHz to 2.1 GHz and is also capable for beam shifting at three different angles (0o, +30o and -30o). Computer Simulation Technology (CST) software is used for antenna simulation. PIN diode switches and hard wire switches are used to represent switches in the simulation and measurement. Very good agreement between simulated and measured results such as return loss, radiation pattern and gain are presented, thus verifying the proposed antennas concepts.
Jurnal Publications
1.H.A.Majid, M.K.A.Rahim, M.R.Hamid and M.F.Ismail, "Frequency and Pattern Reconfigurable Yagi Antenna", Journal Electromagnetic Waves and application, Vol 26, No 2/3, pp 379 - 389, 2012 (ISI)
2.H.A.Majid, M.K.A.Rahim, M.R.Hamid and M.F.Ismail, "A Compact Reconfigurable Frequency Agile Narrow Band Microstrip Slot Antenna ", IEEE Antenna Wireless Propagation Letter, Vol. 11, pp 616 - 619, 2012 (ISI)
3.H.A.Majid, M.K.A.Rahim, M.R.Hamid and M.F.Ismail and F.Malek "Frequency Reconfigurable Wide to Narrow band Monopole with slotted ground plane antenna", Journal Electromagnetic Waves and application, Vol 26, No 11/12, pp 1460 - 1469, 2012. (ISI)
4.H.A.Majid, M.K.A.Rahim, M.R.Hamid N.A.Murad and M.F.Ismail, " Frequency Reconfigurable Microstrip Patch-Slot Antenna", IEEE Antenna Wireless Propagation Letter, Volume 12, pp 218-220, 2013 (ISI)
5.Huda A.Majid, Mohamad K.A.Rahim, Mohamad R.Hamid and Muhammad F.Ismail, " Frequency Reconfigurable Microstrip Patch-Slot Antenna with directional radiation pattern", Progress in Electromagnetic Research, vol 144, pp 319-328, 2014 (ISI)
6.H.A.Majid, M.K.A.Rahim, M.R.Hamid and M.F.Ismail,'Frequency and Pattern Reconfigurable Slot Antenna', IEEE Transaction on Antenna and propagation, Vol 62, Issue 10, pp 5339-5343, October 2014 (ISI)
Proceeding Publications
1.H.A.Majid, M.K.A.Rahim, M. Hamid and M.F.Ismail, "Reconfigurable Wide to Narrow band Antenna for Cognitive Radio Systems" 2011 IEEE International RF and Microwave Conference, Seremban, N. Sembilan, 12-14 Dec 2011
2.Huda A. Majid, Mohamad Kamal A Rahim and Mohd Faizal Ismail, "Reconfigurable Frequency and Pattern Dual Mode Dipole/yagi Antenna", 2011 International Symposium on Antennas and propagation, Jeju Korea, 25-28 October 2011
3.Majid, H.A.; Rahim, M. K A; Hamid, M.R.; Ismail, M.F., "Ultra-wide to narrow band agile reconfigurable frequency microstrip slot antenna," Antennas and Propagation (ISAP), 2012 International Symposium on , vol., no., pp.826,829, Oct. 29 2012-Nov. 2 2012
4.H.A.Majid , M. K. A Rahim, M..Hamid, M.F.Ismail, "Frequency Agile Microstrip Patch to Slot Antenna", The Asia Pacific Microwave Conference 2012 (APMC 2012), Kaohsiung Taiwan, 4-7 Dec 2012
5.Huda A. Majid, Mohamad Kamal A. Rahim, Mohd Rijal Hamid and Muhammad Faizal Ismail, "Frequency Reconfigurable circular Patch antenna" 2013 IEEE International RF and Microwave Conference (RFM2013), Bayview Beach Resort, Penang, 9-11 Dec 2013
RESEARCH TITLE : DESIGN AND DEVELOPMENT OF WIDEBAND METAMATERIAL ANTENNA
Researcher : BASHIR D BALA (PhD-GRADUATED 2013)
Abstract:
There has been increasing interest in Metamaterials in the past 10 years in the scientific communities. However, metamaterials are sometimes regarded as left-Handed materials (LHM) or negative index materials by a lot of people including researchers. Since the concept of artificial LHM were proposed and experimentally realised researchers tried various ways to bring these special material with unusual electromagnetic properties into practical application. At microwave frequencies, some of the potential applications of LHM’s include substrate materials for antenna and microwave components, absorbing materials for engineering and radar applications, high impedance surfaces and Artificial Magnetic Conductors (AMC) and Tunable materials among others. In this research work, LHM will be studied for antenna application with the aim of achieving a wider bandwidth. Currently metameterials based on resonant approach suffers from narrow bandwidth and high material loss. This is attributed to the dependence of the resonance frequency of the DNG structures on its size. To achieve wideband metamaterial antenna, transmission line or non-resonant approach will employed with the aim of merging resonant modes together- the negative order, zero order and positive order modes. Different types of metamaterial antenna will be realised for specific applications such as multi-band, wideband and frequency reconfigurable antennas. Computer Simulation Technology (CST) microwave studio will be employed as the simulation tool and measurement of the result will be obtain via Vector network analyser (VNA) and Anechoic Chamber. The preliminary results obtain is promising when a Slab of DNG structure used as superstrate on a patch antenna improves its bandwidth at 2.4GHz. Also metamaterial antenna using triangular resonator was design for wide band application with the novelty of having only the resonator as the main radiating element.
Jurnal Publications
1.B.D.Bala, M.K.A.Rahim and N.A Murad, ‘Small electrical metamaterial antenna based on coupled electric field resonator with enhanced bandwidth’, Electronics Letter, Vol 50, Issue 3, pp 138-139, 30 Jan 2014 (ISI)
2.B.D.Bala, M.K.A.Rahim and N.A Murad, "Dual Mode metamaterial antenna for wideband applications" , Microwave optical technology letters, Vol 56, Issue 8, pp 1846-1850, August 2014 (ISI)
3.B.D.Bala, M.K.A.Rahim and N.A Murad, "Composite right/left-handed dual band metamaterial antenna with improved gain and efficiency" , Microwave optical technology letters, Vol 56, Issue 7, pp 1575-1579, July 2014 (ISI)
4.B.D.Bala, M.K.A.Rahim, N.A Murad and M.H.Mokhtar, 'Compact Triple Band Metamaterial Antenna Based on Modified Electric-field Coupled-LC Resonator' Jurnal Teknologi, vol 70 pp 51-56, 2014 (SCOPUS)
5.Bashir Dajuma Bala, Mohamad Kamal A.Rahim and Noor Asniza Murad, 'Complementary electric LC resonator antenna for WLAN applications', Applied Physics A, Vol 117, Issue 2, pp 635-639, Nov 2014 (ISI)
6.Bashir D Bala, Mohamad Kamal A Rahim, 'Bandwidth Enhancement Metamaterial Antenna Based on Transmission Line Approach' Microwave Optical technology Letter,Vol 57 Issue 1, pp 252-256, Jan 2015 (ISI)
Proceeding Publications
1.Bashir D.Bala, Mohamad Kamal A Rahim, N.A.Murad, M.F.Ismail, H.A.Majid " Design and Analysis of Metamaterial Antenna Using Triangular resonator", The Asia Pacific Microwave Conference 2012 (APMC 2012), Kaohsiung Taiwan, 4-7 Dec 2012
2.Bala, B.D.; Rahim, M.K.A.; Murad, N.A., "Bandwidth enhanced microstrip patch antenna using metamaterials," IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE), 2012
3.Bashir D.Bala, Mohamad Kamal A Rahim, N.A.Murad, Shahrul Kamal A Rahim " Dual Band metamaetrial with Loaded resonators", The Asia Pacific Microwave Conference 2013 (APMC 2013), COEX Seoul Korea, 5-8 October 2013
4.Bashir D Bala, Mohamad Kamal A. Rahim, Noor Asniza Murad, “A compact triple mode metamaterial inspired Monopole antenna for wideband application”, 2013 International Symposium on Antennas and Propagation (ISAP 2013), Nanjing China, Oct. 23-25, 2013
5.Bashir Danjuma Bala, Mohamad Kamal A.Rahim, Noor Asniza Murad, "An Epsilan negative metamaterial antenna with extended bandwidth" 2013 IEEE International RF and Microwave Conference (RFM2013), Bayview Beach Resort, Penang, 9-11 Dec 2013
6.BD Bala, MKA Rahim, NA Murad, NA Samsuri, ‘A dual band metamaterial antenna with circular polarization’, 8th European Conference on Antenna and propagation (Eucap 2014),pp 917-919, Den Haag, Holland, 2014
7.Bashir D Bala, Mohamad Kamal A Rahim, Noor Asniza Murad and Raimi Dewan, 'Wideband metamaterial antenna employing SRR loading for WiMAx and WiLAN operation', 2014 IEEE Asia-Pacific Conference on Applied Electromagnetic (APACE 2014), Johor Bahru Johor, 8-9 Dec 2014
8.B.D.Bala, M. K. A. Rahim, N.A. Murad N.A Samsuri and M. Khalily, 'Dual band dialectric resonator based on metamaterial', International symposium on Antennas and Propagation (ISAP 2014),Kaohsiung, Taiwan, 2-5 Dec 2014
RESEARCH TITLE : Textile Ultra Wide-Band Antennas For Wearable Applications
Researcher : MAI ABDEL RAHMAN OSMAN (PhD-GRADUATED 2011)
Abstract:
In wearable textile antennas, there are several objectives to be achieved to ensure the robustness and flexibility of wearable devices. This research aimed at investigating the possibilities of designing and fabricating wearable antennas where substrate and conducting parts of the proposed designs are made from textiles. Several types of fabrics for usage as antennas substrates are considered in this investigation. The dielectric properties of substrate materials are examined and measured. To study the feasibility of using fabric substrate materials, rectangular microstrip patch antenna designs are introduced and sufficiently resonated at the ISM band frequency of 5.8 GHz. Further investigations are made with the intention to achieve the objectives by designing two new Ultra Wide-Band (UWB) antennas.Conducting materials that are prominent as Electro-textiles are successfully used for conducting parts of the UWB antennas prototypes. Experiments are carried out where results reveal several scenarios. For fabric substrate materials types, flannel and jeans fabrics are tested and require further investigations, while lint and songket fabrics are considered as non-suitable choice for further investigations. Investigation indicates that flannel and jeans fabrics are recommended for stacking layer purposes. Measured results of UWB antennas using Electro-textile materials such as copper conducting fabric, Shieldit conducting fabric, and conducting thread showed comparable results with ideal copper conducting sheet results. Considering one-layer and three-stacked-layer configurations, the Electro-textile UWB antennas prototypes produces bandwidth results of more than 12 GHz and 17 GHz respectively. Results exposed that the decision on the preferable conducting material depends totally on application requirements, while each of the prototypes has its pros and cons during fabrication and measurements. The measured results of bending effects found to be not significant on textile antennas performances. This research has profound implications for future studies that may one day help to provide the wearer with reliable and comfortable wearable standalone suite.
Jurnal Publications
1.Mai A.R Osman, M.K.A.Rahim, N.A.Samsuri, F.Zubir and K. Kamardin ‘Design, Implementation and Performance of Ultra Wide band Textile antenna’, Progress in Electromagnetic Research B, vol 27, pp 307-325, 2011 (Index Scopus)
2.M.A.R. Osman, M.K.A.Rahim, N.A.Samsuri, H.A.M.Salim and M.F.Ali, ‘Embroidered Fully Textile Wearable Antenna for medical Monitoring applications’, Progress in Electromagnetic Research, Vol 117, pp 321-337, 2011 (Index Scopus)
3.Mai A. R. Osman, M.K.A.Rahim, N. Asmawati Samsuri, M. K. Elbasheer, and Mohammed E. Ali, "Textile UWB Antenna Bending and Wet Performances" International Journal of Antennas and Propagation, Volume 2012 (2012), Article ID 251682, 12 pages, doi:10.1155/2012/251682 (IF = 0.468)
4.M.A.R Osman, M.K.A. Rahim, N.A.Samsuri, M.K.Elbasheer and M.E. Ali, 'UWB wearable Textile antenna', Jurnal teknologi, Vol 58, pp 39 - 44, 2012 (Index Scopus)
5.Mai Abdul Rahman Osman, Mohamad Kamal A Rahim, ‘Wearable Textile Antenna: Fabrics Investigation’, Journal Of Communication and Computer, Volume 7, serial no 68, July 2010 (Non Index )
Proceeding Publications
1.Mai A Rahman, Mohamad Kamal A Rahim, ‘A flexible wearable textile antenna’, 2009 IEEE International Conference on Antenna, propagation and Systems (INAS 2009), Johor Bahru Malaysia, 3- 5 Dec 2009
2.Mai A.R. Osman, M. Kamal A.R.“Wearable Textile Antenna: Fabric Layers Investigation”, Indonesia-Malaysia Microwave Antenna Conference (immac 2010), Jakarta,Indonesia 11-12 June, 2010
3.Mai.A.R.Osman, M. K. A Rahim, S.H.S Ariffin, S.K.S.Yusof “Wearable Textile Antenna: The Investigation of Flannel fabric layers.”, International Symposium on Antennas and Propagation (ISAP 2010), Macau, China, 23-26 November 2010
4.Mai A.R. Osman, M. K. A Rahim, M.Azfar, K. Kamardin, F. Zubir and N.A. Samsuri, “ Design and Analysis UWB Textile wearable antenna”, 5th Europen Conference on Antenna and propagation (Eucap 2011), Rome, Italy, 11 – 15 April 2011
5.Mai A. R. Osman, M. K. A. Rahim, M. F. Ali , N. A. Samsuri and M. R. Kamarudin, "Compact Fully Textile UWB Antenna for Monitoring Applications", The Asia Pacific Microwave Conference 2011 (APMC 2011), Melbourne Australia, 5-8 Dec 2011
RESEARCH TITLE : Triple-Band Dipole Antenna With Artificial Magnetic Conductor For Radio Frequency Identification
Researcher : MAISARAH ABU (PhD-GRADUATED 2010)
Abstract:
The radiation characteristics and input impedance of the dipole antenna will be distorted when the antenna is placed on a metal object. The electromagnetic wave of the antenna is reflected almost entirely by the metallic surface and a 180° phase shift is occurred. In addition, a common dipole antenna has low gain which is about 2.15 dBi. Owing to the high impedance, surface structure called Artificial Magnetic Conductor (AMC) is developed as a ground plane for the dipole antenna to prevent the performance degradation of the antenna caused by metallic objects and to increase the antenna’s gain. Due to the reflected wave of the AMC is in-phase with the antenna current (reflection phase equals to zero), it improves the radiation efficiency and subsequently enhances the gain of the dipole antenna. Thus, due to the great demand in multiband antenna, this research has developed a triple-band dipole antenna with straight and meander structures at Ultra-high Frequency (UHF) and Microwave Frequency (MWF) Radio Frequency Identification (RFID) frequencies; 0.92 GHz, 2.45 GHz and 5.8 GHz respectively. Firstly, the single-band square-patches AMCs are investigated. Then, to obtain a smaller structure of AMC and suitable for RFID applications, two new structures of AMC-HIS are developed. They are single-band AMC called zigzag dipole and dual-band AMC called rectangular-patch with slotted rectangular and I-shaped slot. The parameters that affect the AMC performance are discussed and the performances of the antenna with and without the AMC GP are investigated in terms of return loss, total gain, total efficiency and directivity. From the results gained, in general the power received of the dipole antenna with AMC GP is higher than the power received of the dipole antenna with the absent of AMC GP. Furthermore, a longer reading distance is recorded for the dipole tag antenna backed by AMC structures. For instance, the reading distance for the UHF meandered dipole tag antenna with the 2x2 rectangular-patch with slotted rectangular and I-shaped slot has achieved two times higher compared with the dipole antenna without the AMC GP. While at MWF, its reading distance is increased from 0.8 m to 1.25 m. The performance of the dipole tag antenna with AMC GP attached to the metallic plate size is also tested to verify the dipole tag antenna with AMC GP can be used for metallic object detection in RFID applications.
Jurnal Publications
1.M.Abu, M.K.A.Rahim. 2009. “Triple band Printed Dipole Tag antenna for RFID”, Progress in Electromagnetic Research C, Vol 9, pp 145-153,2009 (Index Scopus)
2.M. Abu, M.K.A.Rahim, O.Ayop, F.Zubir, ‘Triple band printed dipole antenna with single band AMC-HIS’, Progress in Electromagnetic Research B, vol 20, pp 225-244, 2010 (Index Scopus)
3.M.Abu and M.K.A.Rahim, " Single-band and Dual-band Artificial Magnetic Conductor Ground Planes for Multi-band Dipole Antenna", Radioengineering Jurnal, Vol 21, No 4, pp 999 - 1006, 2012 (Index ISI)
4.M. Abu and M.K.A.Rahim, 'Single band Zig zag dipole AMC' Jurnal teknologi, Vol 58, pp 19 - 25, 2012 (Index Scopus)
Proceeding Publications
1.Maisarah Abu, Mohamad Kamal A Rahim, Osman Ayop, “Slotted e-shape Antenna Design for dual frequency operation”, 3rd Europen Conference on Antenna and propagation (Eucap 2009), Berlin, 23 – 27 March 2009
2.M. Abu, M. K. A Rahim, “Triple band printed dipole antenna for RFID application”, International Symposium on Antennas and Propagation (ISAP 2009), Bangkok, Thailand, 20-23 October 2009
3.Maisarah Abu, Mohamad Kamal A Rahim, M.K. Suidi, I.M. Ibrahim, N.M.Nor, ‘Dual band Artifial Magnetic Conductor’, 2009 IEEE International Conference on Antenna, propagation and Systems (INAS 2009), Johor Bahru Malaysia, 3- 5 Dec 2009
4.Maisarah Abu, Mohamad Kamal A. Rahim, M. K. Suaidi, I. M. Ibrahim and N.M. Nor, ‘A Meandered Triple-band Printed Dipole Antenna for RFID’, 2009 Asia Pacific Microwave Conference (APMC 2009), Singapore, 7-10th December 2009
5.Maisarah Abu, M.K.A Rahim and S.A.Hamzah, “A meandered triple band dipole antenna with 920 MHz AMC-HIS”, Antenna and Propagation Symposium (APS2010), Toronto, Canada
6.Maisarah Abu, Mohamad Kamal A.Rahim, M. K. Suaidi, I. M. Ibrahim and N.M. Nor “A Triple-band Dipole Antenna with 0.92GHz AMC-HIS”, International Conference on Computer and Communication Engineering (ICCCE 2010), Prince Hotel & Residence Kuala Lumpur, Malaysia, 11-13 May, 2010
7.M. Abu, M. K. A.Rahim, M. K. Suaidi, I. M. Ibrahim and N.M. Nor “Multi-band printed Dipole Antenna with single band artificial Magnetic conductor Ground Plane”, Indonesia-Malaysia Microwave Antenna Conference (immac 2010), Jakarta,Indonesia 11-12 June, 2010
8.M. Abu, M. K. A Rahim, M.F.Ismail, S.H.S Ariffin “Multi-band Dipole antenna incorporated with single band square patch AMC”, International Symposium on Antennas and Propagation (ISAP 2010), Macau, China, 23-26 November 2010
9.M. Abu, M. K. A Rahim, O.Ayop and F. Zubir, “Design of Triple-band Dipole-type Antenna with Dual-band Artificial Magnetic Conductor Structure”, 5th Europen Conference on Antenna and propagation (Eucap 2011), Rome, Italy, 11 – 15 April 2011
10.M.Abu, M.K.A.Rahim, M.K.Suidi, I. Mohd Ibrahim and N.Md Nor, "The Performance comparison of printed dipole Antenna with two different structures of AMC Ground Plane", 2011 IEEE International RF and Microwave Conference, Seremban, N. Sembilan, 12-14 Dec 2011
11. Maisarah Abu and Mohamad Kamal A Rahim, "Rectangular Patch with Rectangular and I shaped Slot AMC-HIS Design at 0.92 GHz and 2.45 GHz", 2011 International Symposium on Antennas and propagation, Jeju Korea, 25-28 October
RESEARCH TITLE : BROADBAND AND MULTIBAND DIELECTRIC RESONATOR ANTENNA
Researcher : MOHSEN KHALILY (PhD-GRADUATED 2010)
Abstract:
In recent years, dielectric resonator antennas (DRAs) have been targeted as a potential solution for wideband and multiband antennas; they provide wider bandwidth and smaller size than microstrip antennas. The problem in designing this kind of antennas is to design a smaller size broadband antenna especially at low frequencies, because the bandwidth and size of the antenna depend on dielectric resonator constant. This research investigate different methods for wideband and multiband-dielectric-resonator antennas. In the first design, a novel hybrid dielectric resonator antenna excited by a printed monopole antenna is proposed and implemented for multiband application. Measured results show that the proposed DRA can be used in multiband wireless operations ranging from 1.54 GHz to 6.2 GHz. Second design presents a new modified planar dielectric resonator antenna for wideband and multiband applications. Dielectric resonator consists of a rectangular ring-shaped, housed inside the dielectric substrate above the vertical ground plane edge. Peak gain and directivity enhancement are achieved by using only one or two narrow strips, connected to the ground plane. The measured bandwidths are about 73% (2.78~5.95 GHz) for wideband DRA as well as 8% (2.4~2.6 GHz)and 56% (3.3~5.85 GHz) for the dual band DRA. The third design presents simple and compact wideband rectangular dielectric resonator antenna. The bandwidth is enhanced using a proper tapered strip excitation from one side of the dielectric resonator and by adding a shorted narrow strip to the opposite side of the excitation. The proposed DRA with good radiation characteristics offers a measured bandwidth of 96% between 2.13 and 6.08 GHz. Finally, the fourth design is a novel P-shape dielectric resonator antenna for wireless application. Using this P-shape dielectric resonator, a wideband antenna is achieved. The prototype is fabricated and the antenna characteristics are measured. The measured bandwidth is about 80% from 3.5 to 8.2 GHz.
Jurnal Publications
1.M.Khalily and M.K.A.Rahim, ‘ A Novel Hybrid Design of Printed Hemi-Cylindrical Dielectric Resonator Monopole antenna with multibands operation’, Progress in Electromagnetic Research C, Vol 15, pp 175-185, 2010. (Index Scopus)
2.M. Khalily, M.K.A.Rahim, M.R. Kamaruddin, ‘Modified Cylindrical Dielectric resonators Excited with Loaded Fork Monopole antenna’, Microwave Optical Technology Letters, Vol 53 Issue 12, pp 2887 - 2890, 2011 (ISI)
3.M. Khalily, M. K.A Rahim, A. A. Kishk, ‘Bandwidth enhancement and radiation Characteristics Improvement of Rectangular Dielectric Resonator Antenna , IEEE Antenna and Wireless propagation Letter, Vol 10, pp 393 – 395, 2011 (ISI)
4.M. Khalily, M.K.A.Rahim, A.A.Kishk, " Planar Wideband Circularly Polarized Antenna Design with Rectangular Ring Dielectric Resonator and Parasitic Printed Loops", IEEE Antenna Wireless Propagation Letter, Vol 11, pp 905-908, 2012 (ISI)
5.Mohsen Khalily, Mohamad Kamal A.Rahim, Ahmed.A.Kishk and Shadi Danesh" Wideband P-Shaped Dielectric Resonator Antenna ", Radioengineering Jurnal, Vol 22, No 1 pp 281-285, April 2013 (ISI)
6.M.Khalily, M.K.A.Rahim. N.A.Murad, N.A. Samsuri and A.A.Kishk, 'Rectangular Ring-Shaped Dielectric Resonator Antenna for Dual and Wide-Band Frequency' Microwave Optical Technology Letters, Volume 55 Issue 5, pp 1077-1081, May 2013 (ISI)
Proceeding Publications
1.Mohsen Khalily, and Mohamad Kamal A. Rahim, Muhamad Ramlee Kamaruddin ‘Wideband Rectangular Dielectric Resonator antenna design’, 2010 Asia-Pacific Conference on Applied Electromagnetics (APACE 2010) 9th – 11th November 2010 , Port Dickson, Negeri Sembilan, Malaysia
2.Mohsen Khalily, and Mohamad Kamal A. Rahim, Muhamad Ramlee Kamaruddin ‘A Novel P shape dielectric resonator antenna for Wideband application’, 2010 Asia-Pacific Conference on Applied Electromagnetics (APACE 2010) 9th – 11th November 2010 , Port Dickson, Negeri Sembilan, Malaysia
3.Mohsen Khalily, M. K. A Rahim, M.R. Kamaruddin, M. Shanesin and S. Danesh, “ Ultra Wideband printed Monpole antenna with dual band Circular Polarization”, 5th Europen Conference on Antenna and propagation (Eucap 2011), Rome, Italy, 11 – 15 April 2011
4.M. Khalily, M.K.A.Rahim, M.R. Kamaruddin, "A Compact Circularly Polarized and Wideband Rectangular Dielectric Resonator" 2011 IEEE International RF and Microwave Conference, Seremban, N. Sembilan, 12-14 Dec 2011
RESEARCH TITLE : DUAL BAND MICROSTRIP ARRAYS AND ULTRA WIDE BAND ANTENNAS WITH ELECTROMAGNETIC BAND GAP STRUCTURES
Researcher : THELAHA MASRI (PhD-GRADUATED 2009)
Abstract:
This research focuses on the possibilities of integrating Electromagnetic Band Gap (EBG) structures with Dual Band Microstrip Antenna’s Array (DbMSAA) and Ultra Wide Band (UWB) antenna, with an objective to further improve the antennas’ performance by reducing, if not eliminating, the limitation that they have. From the parametric study of the already established two-dimensional mushroom shaped EBG structures, novel designs of dual band-gaps EBG structures are proposed and fractal shapes were implemented to achieve the objective. As a result, guidelines, graphs and tables of the EBG structures’ designs and configurations were put forward for reference. A DbMSAA has been purposely designed to represent a problematic antenna and, through the incorporation of EBG structures via novel and innovative techniques, the performance of the antenna has been improved, upgraded and realized. The grating lobes diminished, radiation patterns become more symmetrical and its gain increased. On the other hand, UWB systems could become a jammer for the numerous licensed services if it does not comply with the regulations mandated by the Federal Communication Commission. To solve this problem, a single unit of EBG lattice is incorporated into a model of the UWB antenna to act as a ‘band stop filter’ in such a way that the radiating power is reduced to a level that will not intrude any existing channels. Finally, other filtering techniques, which seem to be much simpler such as stubs and defected ground plane (DGS) techniques were also investigated and compared to the EBG structures. Stubs could filter out and stop the targeted band of frequencies but undesirably, it upset the input impedance of the antennas, while the DGS technique is only suitable for thin substrate of less than 0.5 mm. These circumstances confirmed that the EBG structures performed better, and validate the works and concept proposed. Further research and works that needs to be carried out are also proposed in the conclusion of this thesis
Jurnal Publications
1.T. Masri and M.K.A.Rahim, ‘Dual Band Microstrip Antenna Array with a Combination of Mushroom, Modified Minkowski and Sierpenski EBG’, IET Microwave Antenna and Propagation, volume 4, pp 1756-1763, 2010 (Index ISI)
2.T.Masri, M.K.A.Rahim, O.Ayop, F.Zubir, N.A.Samsuri, H.A.Majid, Electromagntic Band gap structure incorporate with dual band microstrip antenna’, Progress in Electromagnetic Research M, vol 11, pp 111-122, 2010 (Index Scopus)
3.T.Masri, M.K.A.Rahim, H.A.Majid, O.Ayop, F.Zubir and M.N.A.Karim, ‘Electromagnetic Band Gap structure for Planar Ultra Wide band antenna’, Journal of Electromagnetic Waves and Application, vol. 24, pp 229 – 239, 2010 (Index ISI)
Conference Publications
1.T. Masri, M.K.A.Rahim, M.H. Jamaluddin, A.Asrokin, ‘Bandwidth Enhancement of a Narrowband Rectangular Microstrip Antenna on a radial EBG patch structure’, International Symposium on Antennas and Propagation (ISAP 2006), 1-4th November 2006, Singapore (Proceeding Index Scopus)
2.T.Masri, M.K.A.Rahim, M.H. Jamaluddin, A. Asrokin, ’‘Bandwidth Enhancement of a Narrowband Rectangular Microstrip Antenna on a Spiral Fan Shape EBG Patch structure’, 2006 International RF and Microwave Conference (RFM 2006), 12-14th September 2006, Putrajaya, Malaysia (Proceeding Index Scopus)
3.T. Masri, M. K. A.Rahim, M.N. A Karim ‘A Novel 2D Sierpenski Gasket EBG structure for Multiband Microstrip Antenna’, 2007 Asia-Pacific Conference on Applied Electromagnetics (APACE 2007) 4th – 6th December 2007 , Melaka, Malaysia (Proceeding Index Scopus)
4.T Masri , M.K.A.Rahim, M.N.A.Karim, ‘A Novel 2D Minkowski Gasket EBG Structure for Multiband Microstrip antenna’, European Conference on Antenna and Propagation (EuCAP 2007) 11th – 16th November 2007, Edinburgh U.K (ProceedingIndex Scopus)
5.T.Masri, M.K.A.Rahim, F. Zubir, O.Ayop, M.N.A.Karim, H.A.Majid, “Microstrip Antenna Array via enhancement using EBG structure’, 2008 Conference on Radio and Microwave (RFM 2008) 2- 4 Dec 2008 (Proceeding Index Scopus)
6.T.Masri, M.K.A.Rahim, O. Ayop, “Dual Band Microstrip Array Antenna Radiation Characteristic Enhancemenet via Novel Band rejection technique using EBG”, 2008 Asia Pacific Microwave Conference (APMC 2008), 16 - 20 Dec 2008 (Proceeding Index Scopus)
MASTER STUDENTS GRADUATED
RESEARCH TITLE: UHF ANTENNA TAG FOR WIRELESS MONITORING SYSTEM
Researcher:NorSaidah bt Muhamad Nadzir (Master graduated 2019)
Abstract
There are a lot of variation of monitoring systems available in the market currently that ranges from utilizing software application such as tracker app in phones which uses GPS to hardware technologies such as chip tracker that uses Bluetooth. On that note, the idea of integrating UHF RFID and Raspberry Pi 3 to develop a monitoring system would be a great step forward in monitoring system technology as RFID are proven to perform well in both indoor and outdoor environment as it utilizes backscatter coupling with reader and tag. Thus, the main focus of this project is to realize a monitoring system that could work in both indoor and outdoor environment based on the integration of UHF RFID and Raspberry Pi 3, develop a low cost UHF RFID tag, and to measure its performance through both simulation and experimental prototype. The proposed approach has several notable merits, namely UHF RFID tag is easier to manufacture, has cheaper production cost, and it has larger detection range compared to the other passive RFID systems. Plus, Raspberry Pi 3 are chosen to execute this system as it has the best computing power for its compact size and also provide room for future enhancements and upgrade. The performance of the proposed method is evaluated in two ways: simulation and experimental prototype. The simulation results of the UHF RFID tag S11 falls at 0.93 GHz with bandwidth of 627 Hz and gain of 1.5 dB. From the experimental prototype measurement of the fabricated UHF RFID tag, it was found that the tag could perform in the range frequency of 0.88 GHz to 0.97 GHz. The conclusion of the study suggests that the results obtained from this research could be utilised for further improvement of wireless monitoring systems.
RESEARCH TITLE: WIRELESS SENSOR NODE FOR MONITORING SYSTEM
RESEARCHER: AMERUL ZABERI (Master graduated 2019)
Abstract:
Raspberry Pi is a mini computer that has a wide variety of purposes to be designed. In this project, it acts as a microcontroller that control sensors such as, Pi camera module and the MFRC522 RFID for surveillance and tracking purposes. The platform used is Raspberry Pi 3, driven by a 1.2 GHz 64-bit quad-core ARM Cortex-A8 CPU and 1 GB RAM. The Pi camera installed, features a 5 MP, with fixed focus lens, has the capabilities of capturing 2592 × 1944 pixels static image, and supports 1080p, 720p, and 640 × 480p video. This system operates in a wireless environment using wireless sensor node where an area is monitored by a personal computer or smartphones. To combine multiple sensors, an algorithm is developed where both platforms are viewed on a web interface. Mikrotik is used as an access point where it can record different types of results, and UDOO as an extender to widen the coverage area. The performance of the wireless connectivity strength and speed are investigated by applying different types of antennas where it gives major effects on the data transmission rates
RESEARCH TITLE : METAMATERIAL INSPIRED MULTIBAND ANTENNA AT UHF BAND
Researcher : Nor Afifah Borhan (Co Supv Master - Graduated 2019)
Abstract:
Metamaterials are basically artificial material. It has greater advantage over conventional microstrip technology and more compact. Its individual elements, called unit cell mimic the microscopic in conventional material. The unit cells are repeated and form a structure for the required applications. Metamaterial elements can be fabricated on rigid substrate using resonators such as split-ring resonator (SRR) and its complementary counterpart (CSRR). A multiband metamaterial antenna can be realized by having different frequencies at different modes. By integrating the active elements, the bands can be merging or split. However, the integration does need a proper consideration on the tiny structure of each unit cells. The unit cells for multiband and the configurations for reconfiguration will be studied in this work. Compact and small antennas are important for the digital TV’s application. Metamaterial with the negative permittivity or permeability seems useful for the development of small antenna at Ultra High Frequency (UHF) band.
RESEARCH TITLE : UHF ANTENNA FOR DVB SYSTEM
Researcher : Nur Syahirah Mohd Yaziz (Master - Graduated 2018)
Abstract:
This research focus on the design and development of UHF antenna for Digital TV broadcasting system. The concept of fractal structure is introduced to reduce bthe size of the antenna. First and second iteration of fractal koch is investigated to and designed. The gain of the antenna is improved by incorporating the active device and the performance between passive and active are investigated. The antenna has been designed using the concept of log perioidic antenna which produce a wider bandwidth The proposed design will be simulated to achieve a design that meets targeted specification. This research expects to demonstrate the feasibility of this new technique by applying it to fully integrated antenna-amplifier front-end solutions. It also expects that this antenna will be able to provide high gain, good reflection coefficient, good radiation pattern and beam forming. With this system, the performance of the application applied can be observed using the proposed active antenna. This research will focus on active antenna for the DVB TV application.
RESEARCH TITLE : MULTIBAND TEXTILE ANTENNA FOR WEARABLE APPLICATION
Researcher : NURUL JANNAH RAMLY (Master - Graduated 2018)
Abstract:
Development in wearable electronics and antennas is driven by the demand for lighter and smaller personal electronics devices. Integrating antenna into normal garments would allow lower profile and more portable electronics to be practical without affecting their performance. Embroidery antennas posses several advantages for wearable application due to ability of attached to the clothes. The feasibility of investigating Ultra High Frequency (UHF) are made from fully conductive threads that were used for the embroidered as well as the conducting parts of the designed antenna. Simulated and measured results show the proposed and antenna design meets the requirements of wide working bandwidth with compact size, washable and flexible materials. These embroidered antennas will require extra adhesive glue for connector and directly sewing to the garment, which is conducive to being washed and extend consumer lifecycle. Computerized embroidery has been adopted to fabricate the textile antennas in this project. This technology provides high speed, mass-manufacturing capability, accurate and easily modified embroidered antenna designs. The antenna can be automatically integrated into the manufacturing process which further reduces the costs and adds to the aesthetic appeal. The computerized embroidery machinery was discovered by using AutoPunch software. Results in terms of return loss, bandwidth, radiation pattern, current distribution as well as gain and efficiency are presented to validate the usefulness of embroidered antenna.
RESEARCH TITLE : SPECTRUM SENSING USING ENERGY DETECTION FOR RECONFIGURABLE ANTENNA
Researcher : KHAIRUL HILMI YUSOF (Master - GRADUATED)
Abstract:
Rigorous development in cognitive radio give birth to software defined radio (SDR) that can somewhat realize the dream of cognitive radio. The SDR can be used with a reconfigurable antenna to achieve the full cognitive radio system. So to prove the concept of cognitive radio system, development on spectrum sensing algorithm that can work with antenna will be carried out. Investigation on the effect of different antenna used and real environment measurement of the cognitive radio need to be done. Initial result shows that a cognitive radio system using energy detection spectrum sensing can perform better in a high SNR value. The probability of false alarm can be reduced if a high number of samples are taken. From the initial result, it can be concluded that if a high gain antenna is used and adequate number of sample is taken, the performance of the cognitive radio system can be boosted
RESEARCH TITLE : COMPACT MICROSTRIP ANTENNA ARRAY FOR POINT TO POINT COMMUNICATION
Researcher : MUHAMMAD HAZMI MOKHTAR (Master - GRADUATED)
Abstract:
This project describes the compact design of microstrip patch antenna array operating at 2.4 GHz frequency band for point to point or bridging communication system. The array of four by four microstrip square patch antennas has been investigated with new technique using slot to reduce the existence size of microstrip antenna. The aray of the new antenna will be incorporated with Artificial Magnetic Conductor(AMC) to increase the gain of the antenna. The properties of the antenna is investigated in term of return loss, radiation pattern, bandwidth and gain of the antenna. The performane of the antenna will be compared with the existing microstrip antenna array using the setting up of point to point wireless communication system.
RESEARCH TITLE : HYBRID DIELCTRIC RESONATOR WITH PATCH ANTENNA AT UHF FREQUENCY
Researcher : MUHAMMAD ISHAK BIN ABDUL SUKUR (Master - GRADUATED)
Abstract :
This project proposes a hybrid Dielectric Resonator Antenna with patch antenna, also known as dielectric-resonator-on patch (DRoP) at UHF band ranged from 400 MHz untill 900 MHz. At this particular frequency band, the size of the antennas such as the patch antenna is relatively big. The usage of the hybrid DRA can reduce the size of the antenna, while the patch antenna will help in expending the antennas bandwidth. At lower frequency, the efficiency of the system decreases, so the DRA was used to provide higher system efficiency. This also will later be introduced in the public safety and television broadcasting applications.
RESEARCH TITLE: Switchable and Tunable Multiband Slot Dipole Antenna
Researcher: IZNI HUSNA (Co Supv Master - GRADUATED)
Abstract
Developments of frequency reconfigurable antennas in the wireless communication systems have attracted a lot of attention recently. Most reported antennas have narrowband to narrowband reconfiguration and multiband to multiband reconfigurations. In this research, a slot dipole antenna has been introduced with the ability to produce a multiband to narrowband reconfiguration. This type of antenna can suppress the problem of co-site interferences. Thus, two types of frequency reconfigurable antennas are studied and discussed which are switchable and tunable multiband antennas. The switchable multiband antenna is reconfigured by using Radio Frequency (RF) switches. The proposed antenna is capable to reconfigure from multiband to dual and/or single band. By having seven configurations of switches, this antenna can operate at 2.4 GHz, 3.5 GHz and/or 5.2 GHz. The antenna is able to have three states of single-band, three states of dual-band and one state of tripleband. Meanwhile, the tunable multiband antenna is reconfigured by using variable capacitors. The proposed antenna is capable to have a wide frequency tunability range for dual or single band operation (1.5 GHz - 4.5 GHz, ratio of 3:1). Each antenna has been successfully designed, fabricated and tested. The simulation and measurement results were analysed and presented in terms of reflection coefficient, radiation pattern and gain. The simulation and measurement results have been compared and a very good agreement was achieved. The reflection coefficient average accuracies of 98% has been achieved. These proposed antennas are suitable for future multi-mode applications such as cognitive radio systems.
RESEARCH TITLE: DESIGN AND DEVELOPMENT OF MULTIBAND AND ULTRA WIDEBAND TEXTILE ANTENNA FOR WEARABLE APPLICATION
Researcher: MOHD EZWAN JALIL (Master - GRADUATED)
Abstract
In recent year, a wearable system has been growing rapidly for monitoring, tracking and navigating activities in healthcare, medicaland military sector. A flexible and comfortable antenna is required for wearable application. The flexible textile antenna using denim materials are proposed for wearable application due to robustness, conformal and light-weight type of material. The permittivity of denim material is 1.7 and the loss tangent of denim is 0.025 are discovered using coaxial probe method for dielectric measurement. Two types of conducting element for textile are investigated which are Shield fabric and copper foil tape to evaluate the antenna performance with different conducting element. Two designs are proposed for wearable application. For the first design, a multiband Koch fractal textile antenna is designed which resonate at 0.9, 2.45GHz and 5.8GHz. For the second design, a coplanar waveguide (CPW) ultra wideband (UWB)textile antenna which cover the frequency from 2.5GHz until 15 GHz The detail analysis are conducted on a multiband anda ultra wideband (UWB) antenna in term of bending, wetness condition and on body measurement.
RESEARCH TITLE : DESIGN AND DEVELOPMENT OF TEXTILE ARTIFICIAL MAGNETIC CONDUCTOR INCORPORATE WITH PLANAR DIPOLE ANTENNA
RESEARCHER : Muhammad Azfar Abdullah (Master - GRADUATED)
Abstract
The radiation characteristics of wearable dipole antenna which are omni-directional radiation pattern towards human body are very crucial for wearable application. In order to avoid the radiation towards human body, artificial magnetic conductor (AMC) are designed and analysed. The purpose of implementing the textile AMC is to reduce the back radiation towards the human body from the antennas radiation characteristics. This will increase the gain of the antenna when incorporate with the AMC. By implementing this concept, the dipole antennas beam direction is shifting outward from the human body and the antenna’s gain is increased. In this work, the incorporation of dipole antenna with AMC is described and analyzed. The propose antenna and AMC is designed, simulated and analysed using CST Microwave studio. The antenna and the AMC is fully made of textile material. The antenna's substrate is made from denim jeans with a tangential loss of 0.019 and dielectric constant of 1.67 with 0.67mm substrate thickness. The radiating elements are made from two different conductive fabric which are shieldit super fabric and purely copper fabric. Three configurations of artificial magnetic conductor are presented and discussed. A textile dipole antenna incorporate with 3 x 3 arrays of textile magnetic conductor is designed at 2.4 GHz The second design is at 5.8 GHz with 3 x 3 arrays of AMC. Finally, both designs are combined to become a dual band artificial magnetic conductor. The properties of the fabric such as bending effect, wetness effect and on-body measurement are investigated for the antenna incorporate with AMC. The different position of the dipole antenna above the AMC which may alter the performance of the antenna is also analysed and discussed. The performances of the dipole antenna with and without AMC are compared. A Very good agreement between simulated and measured results such as return loss, radiation pattern and gain is achieved, thus verifying the proposed antennas concepts.
RESEARCH TITLE : ENERGY ABSORPTION BY HUMAN BODY IN THE PRESENCE OF CONDUCTIVE ITEM
Researcher : NAZIRAH BINTI OTHMAN (Co Supv Master - Graduated)
Abstract :
This study quantifies the effects of human body on antenna performance and SAR in the presence of conductive metallic object focussing on the area of human wrist. Conventionally, the mobile handset is left inside the trousers pocket where a certain amount of electromagnetic energy passes through the body rather than being directly radiated. A anatomically realistic Voxel body model is exposed to the near-field radiation. The position of the human sensitive organ (testicles) is closed to the radiation source. This study was carried out using CST Microwave Studio which is based on Finite-Integration Technique. Three types of common metallic objects and medical implant are used in this research; coin, ring, zip and intramedullary rod in order to determine the effect of metallic object on antenna performance and SAR. The results are discussed in term of S11, antenna radiation pattern and energy absorption by the human biological tissue (inside the human leg and testicles) in the presence of conductive metallic items.
RESEARCH TITLE : Dual Layer Printed Microstrip Reflectarray Antenna With Minkowski Radiating Element Shape
Researcher : AMERUDEEN WAHID (Master - Graduated)
Abstract :
The planar microstrip reflectarray antenna is a combination of the advantages of parabolic reflector and phase array antenna. Reflectarray is a planar antenna consisting of an array of microstrip patches on a grounded substrate, where the required phase shift is obtained by tuning the dimension of the radiating patches. Whenever a signal from a primary source propagates towards the reflectarray, the incident signal is scatter towards the intended propagation. Reflectarray is widely use in communication system especially in the satellite communication technology to replace the bulky and high complexity parabolic dish antenna. In this research project, a fractal shape (Minkowski) is introduced as a radiating element shape. Three configurations for a dual layer printed reflectarray antenna are designed and analyze at 11 GHz. The configurations are two staked arrays composed of two Minkowski patches, two staked arrays composed of Minkowski and Square patches and lastly two staked arrays composed of two Square patches. To evaluate the performance of the configuration, a modeling design is carried out using CST Microwave Studio. From the unit cell simulation of the 3 configurations, the unit cell of two staked arrays composed of Minkowski has widest phase range of up to 420º and lowest insertion loss which is lower than 0.6 dB. To fully validate the reflection phase simulation setup, the unit cells are characterized and measured in waveguide simulators. A dual layer printed microstrip reflectarray antenna with Minkowski radiating shape elements prototype has been designed, built and measured to verified and compared to the simulation modeling result. The prototype has been constructed using Taconic RF-35. From the measured radiation pattern at 11 GHz shows a HPBW of 4.1º, a side lobe level of –15 dB and a maximum directivity of 29 dBi. Additionally, the measurement of the power receive was conducted within a frequency range of 10 – 12 GHz.
RESEARCH TITLE : Frequency Reconfigurable Log-Periodic Antenna Design
Researcher : MUHAMMAD FAIZAL ISMAIL (Master - Graduated)
Abstract :
The concept of reconfigurable antenna is widely used as additional features of reconfigurable ability for future wireless communication system. There are various configurations of reconfigurable antenna such as monopole, dipole and log-periodic wideband antenna. The integrations of reconfigurable antennas with radio frequency (RF) switches are needed to perform the switchable ability. In this research, a log-periodic antenna (LPA) has been designed to perform a wideband frequency operation by connecting thirteen square-patch antennas using inset feed line technique. Then, the reconfigurable log-periodic antenna (RLPA) is designed by connecting positive-intrinsic-negative (PIN) diodes at every transmission lines with a quarter-wave length radial stub biasing. The representation of real PIN diodes and the locations of biasing circuits in simulation are also included. Three different sub-band frequencies with a bandwidth of 20% (3 - 4, 3.7 - 5, and 4.8 - 6 GHz for each band) are configured from the total of 73% bandwidth (3 to 6 GHz) of the wideband operations by switching ON and OFF of the PIN diode. Other sub-bands or narrow band can also be configured by selecting other group of patches. Validation for the LPA and RLPA is achieved by comparing the simulated and measured radiation patterns. The measured half-power beamwidth (HPBW) for LPA are 62°, 58° and 72° at frequency 3.4 GHz, 4.0 GHz and 5.8 GHz, respectively, while 73°, 67° and 72° for RLPA at the same frequency band. The simulated gain for LPA and RLPA are around 4.9 dB and 5.0 dB respectively, while the measured gain is around 5.5 dBi for LPA and 5.7 dBi for RLPA within a frequency range of 3 – 6 GHz. All the structures have been fabricated and the measurement results show accuracies of 97.5% for return loss, 80.2% for gain and 98.4% for HPBW with the simulation results.
RESEARCH TITLE : ELECTROMAGNETIC BAND STRUCTURE INCORPORATED WITH UWB ANTENNA
Researcher : OSMAN AYOP (Master - Graduated)
Abstract :
This research focuses on electromagnetic band gap (EBG) structures and their application on ultra-wideband antenna. The first phase involves a parametric study of conventional 2-D mushroom-like EBG (mEBG) structure using method of suspended transmission line. The observation on 9 patch elements of mEBG structure is proposed to indicate the periodic arrangement. The parametric study is conducted based on patch width, gap between elements, substrate thickness, via radius and dielectric constant. Then, a new shape of EBG structure named as slotted patch EBG (spEBG) structure is presented. This new structure provides additional stop band frequency at higher frequency band and it is suitable to be used as dual band rejecter. A parametric study is also conducted for this structure to understand the characteristic of the stop band frequency for different parameters effect. All the results are presented in form of table and graph. The second phase involves the design of a new structure of ultra-wideband (UWB) antenna. Based on simulation, this antenna operates from 2.7 GHz to 13.8 GHz while from measurement, it operates from 2.9 GHz to 13.9 GHz. The third phase presents the incorporation of UWB antenna with single mEBG structure which is operates at 5.8 GHz and also spEBG structure operates at 3 GHz and 8 GHz. The simulated S21 and radiation pattern show that the single mEBG structure can be used as single frequency band rejecter while single spEBG structure can be used as dual frequency band rejecter. All the structures have been fabricated and the measurement result shows a good agreement with the simulation results in term of stop band frequency, return loss, and radiation pattern.
RESEARCH TITLE : Microstrip Reflectarray Antenna With Minkowski Shape Radiating Element
Researcher : FARID ZUBIR (Master - Graduated)
Abstract :
Microstrip Reflectarray Antenna (MRA) is an alternative for high gain antenna, which combines some of the most noticeable features of a traditional parabolic reflector antenna with microstrip array technology. Since the structure is flat, phase compensation is mandatory in designing MRA in order to have the same behaviour and functionality as the conventional parabolic reflector-type antenna. The concept is based on analysis from the reflection coefficient of individual cells. By varying the physical parameter of each reflectarray unit cell, the required phase-shift can be obtained and will scatter the incident communication signal towards the intended direction of propagation. In this work, several configurations of reflectarray unit cells using fractal shapes as the radiating element such as Koch-square, Koch-triangle and Minkowski have been analyzed and compared with the square shape at 11 GHz. A unit cell configuration with a Minkowski shape as the radiating element printed on RF-35 substrate of thickness of 1.524 mm is suitable and can provide acceptable phase range (305°) and low insertion loss (< -0.4 dB). At 11 GHz, the MRA with Minkowski elements is found to have a higher gain of 29.6 dB and a lower side-lobe level (SLL) of -25 dB when compared to the conventional MRA with square elements which gives 27.4 dB gain and -19 dB SLL respectively. Validation for the MRA with Minkowski elements is achieved here by comparing the simulated and measured radiation patterns. Additionally, the margin difference between the sweeping realized gain (simulation) and the sweeping power received (measurement) is compared within a frequency range of 10 – 12 GHz.