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M. K. A. Rahim

Bio: M. K. A. Rahim is an academic researcher from Universiti Teknologi Malaysia. The author has contributed to research in topics: Antenna (radio) & Microstrip antenna. The author has an hindex of 12, co-authored 84 publications receiving 554 citations.


Papers
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Proceedings ArticleDOI
01 Dec 2008
TL;DR: In this article, a design on array dielectric resonator antenna using disk shape is described, which is used for IEEE 802.11b/g wireless LANs, and the antenna has been fabricated on the FR-4 microstrip board using the wet etching technique.
Abstract: This project describes a design on array dielectric resonator antenna using disk shape. The dielectric resonator antenna (DRA) consists of high dielectric constant materials, high quality factors and mounted on a grounded dielectric substrate of lower permittivity. DRA is fabricated from low-loss and high relative dielectric constant material of various shapes whose resonant frequencies are functions of the size, shape and permittivity of the material. Two dielectric resonators is introducing as an array. The selected dielectric disks are operating at frequency of 2.4 GHz with dielectric constant of 34.73. The microstrip transmission line has been used as a feeding line for the resonator. The microstrip line is quarter wavelength where the frequency that applied from the input can get same with the output and divider was introduced in this layout. The simulation process was done using Computer Simulation Technology (CST) Microwave Studio. The antenna has been fabricated on the FR-4 microstrip board using the wet etching technique. The DRA is operating at the frequency bands used for IEEE 802.11b/g Wireless LANs.

36 citations

Proceedings ArticleDOI
01 Dec 2011
TL;DR: In this paper, the simulation of PIN diode as a switch on reconfigurable antenna is described and the results show that the separation of biasing circuit and antenna give a better performance in terms of return loss and current distribution.
Abstract: The investigation and simulation of PIN diode as a switch on reconfigurable antenna are described in this paper. The simulation of the PIN diode model is constructed on CST Simulation tools with the integration of single patch antenna. The radial stub biasing circuit is used for fabrication with the antenna. Three different locations of PIN diode with radial stubs biasing circuit are investigated and analyzed. The result shows the separation of biasing circuit and antenna give a better performance in term of return loss and current distribution.

32 citations

Journal ArticleDOI
TL;DR: In this paper, a novel frequency and pattern reconfigurable Yagi antenna is proposed, which is formed by a driver, a reflector and two directors, and switches using a PIN diode at the arms of the driver element produces three switchable frequencies at 1.25 GHz, 1.85 GHz and 2.45 GHz.
Abstract: A novel frequency and pattern reconfigurable Yagi antenna is proposed. The antenna is formed by a driver, a reflector and two directors. The introduction of switches using a PIN diode at the arms of the driver element produces three switchable frequencies at 1.25 GHz, 1.85 GHz and 2.45 GHz. By controlling the switches at the directors and reflector, the radiation pattern can be configured to near omni-directional pattern or directional pattern at those three frequencies. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses and the radiation patterns, are presented and compared. It was found that the gain of the antenna increases from 3.3 dB to 5 dB in a directional pattern, when compared to the near omni-directional pattern.

28 citations

Proceedings ArticleDOI
01 Dec 2005
TL;DR: In this article, a multiband Sierpinski carpet antenna is proposed for multiband operation, which has a low cost of fabrication and low profile features of microstrip antennas, attract many researchers to investigate the performance of this antenna in various ways.
Abstract: Low cost of fabrication and low profile features of microstrip antennas, attract many researchers to investigate the performance of this antenna in various ways. Today, fractal antenna becomes popular among the researcher because they have a peculiar properties that make them suitable for multiband applications. Fractal technologies allowed us to design miniature antennas and integrate multiple telecommunication services such as cellular (GSM 900 and GSM 1800), wireless LAN, GPS and HiperLAN into a single device. Microstrip Sierpinski carpet antenna is proposed for a multiband operation. The fractal antenna offer solutions for the integration of all this application.

25 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this paper, a dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed.
Abstract: A novel wearable dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed. By using brass eye-lets and a combination of conducting and non-conductive textile materials, a half-mode substrate integrated waveguide cavity with ground plane is realized that is very compact and flexible, while still directing radiation away from the wearer. Additional miniaturization is achieved by adding a row of shorting vias and slots. Beside excellent free space performance in the 2.4 and 5.8 GHz bands, respectively, with measured impedance bandwidth of 4.9% and 5.1%, maximal measured free-space gain of 4.1 and 5.8 dBi, and efficiency of 72.8% and 85.6%, very stable on-body performance is obtained, with minimal frequency detuning when deploying the antenna on the human body and when bent around cylinders with radii of 75 and 40 mm. At 2.45 and 5.8 GHz, respectively, the measured on-body gain is 4.4 and 5.7 dBi, with sufficiently small calculated SAR values of 0.55 and 0.90 W/kg. These properties make the proposed antenna excellently suited for wearable on-body systems.

198 citations

Journal ArticleDOI
TL;DR: A compact and flexible circularly polarized (CP) wearable antenna is introduced for wireless body-area network systems at the 2.4 GHz industrial, scientific, and medical (ISM) band, which is implemented by employing a low-loss composite of polydimethylsiloxane and silver nanowires.
Abstract: A compact and flexible circularly polarized (CP) wearable antenna is introduced for wireless body-area network systems at the 24 GHz industrial, scientific, and medical (ISM) band, which is implemented by employing a low-loss composite of polydimethylsiloxane (PDMS) and silver nanowires (AgNWs) The circularly polarized radiation is enabled by placing a planar linearly polarized loop monopole above a finite anisotropic artificial ground plane By truncating the anisotropic artificial ground plane to contain only 2 by 2 unit cells, an integrated antenna with a compact form factor of 041 λ 0 × 041 λ 0 × 0045 λ 0 is obtained, all while possessing an improved angular coverage of CP radiation A flexible prototype was fabricated and characterized, experimentally achieving S 11 <− 15 dB, an axial ratio of less than 3 dB, a gain of around 52 dBi, and a wide CP angular coverage in the targeted ISM band Furthermore, this antenna is compared to a conventional CP patch antenna of the same physical size, which is also comprised of the same PDMS and AgNW composite The results of this comparison reveal that the proposed antenna has much more stable performance under bending and human body loading, as well as a lower specific absorption rate In all, the demonstrated wearable antenna offers a compact, flexible, and robust solution which makes it a strong candidate for future integration into body-area networks that require efficient off-body communications

129 citations

Journal ArticleDOI
31 Aug 2012
TL;DR: In this article, a design of stacked rectangular dielectric resonator antenna (RDRA) with wide bandwidth, in the range of 13.56 % is described, which exploits two low-Q modes with overlapping bandwidths to achieve a wide continuous bandwidth.
Abstract: This paper presents a design of stacked rectangular dielectric resonator antenna (RDRA) with wide bandwidth, in the range of 13.56 % is described. The antenna exploits two low-Q modes with overlapping bandwidths to achieve a wide continuous bandwidth. This is achieved using low-permittivity DRA volume placed on high permittivity DRA volume. The antenna consists of dielectric constant of 10 and 32, stacked vertically to obtain improved bandwidth as compared to the conventional RDRA. A 50 Ω microstrip line is used in the proposed antenna as a feeding mechanism. Physical parameters of stacked RDRA have been optimized by extensive simulations using Ansoft HFSS. The parameters of antenna are 17x7x4.56 mm 3 with grounded substrate size: 80x50 mm 2 . The prototype is fabricated. Measured and simulated results are both in good agreement. The prototype antenna designed to operate in band from 5.0 to 5.7 GHz with measured gain at 5.2 GHz resonant frequency. The proposed antenna is suitable for wireless local area networks (WLAN) applications in 5 GHz frequency band (in the frequency range 5.15-5.35 GHz and 5.5-5.7 GHz). This stacked RDRA exceeds the bandwidth requirements for IEEE 802.11a WLAN applications within a required VSWR. Parametric studies of the stacked DRA are presented.

126 citations

Patent
30 Jun 2014
TL;DR: In this article, an agile antenna that beam-steers radio frequency (RF) signals by selectively activating/deactivating tunable elements on radial-waveguides using direct current (DC) switches is presented.
Abstract: Embodiments are provided for an agile antenna that beamsteers radio frequency (RF) signals by selectively activating/de-activating tunable elements on radial-waveguides using direct current (DC) switches The antenna comprises two parallel radial waveguide structures, each comprising a first radial plate, a second radial plate in parallel with the first radial plate, and conductive elements positioned vertically and distributed radially between the two plates The radial waveguide structure further includes a plurality of quarter RF chokes which are connected to the conductive elements via respective micro-strips and tunable elements The two parallel radial plates are separated by a height determined according to a desired transmission frequency range for RF signals, a length of the micro-strips, a diameter of the conductive elements, and a clearance space around each one of the conductive elements

123 citations