Siti Zuraidah Ibrahim
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Preferred name
Siti Zuraidah Ibrahim
Official Name
Siti Zuraidah, Ibrahim
Alternative Name
Ibrahim, Siti Zuraidah
Binti Ibrahim, Siti Zuraidah
Ibrahim, Siti Z.
Ibrahim, S. Z.
Main Affiliation
Scopus Author ID
35193912700
Researcher ID
DUU-6589-2022

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Compact multilayer wideband symmetric five-port reflectometer

2017-04-01 , Samir Salem Al-Bawri , Mohd Faizal Jamlos , Siti Zuraidah Ibrahim , Syed Alwee Aljunid Syed Junid

This article presents a new design of a wideband, compact, and low-cost symmetric five-port reflectometer (5PR). The proposed 5PR features a wide operational bandwidth of 3240 MHz (about 162% centered at 2 GHz). Five-symmetric branch-lines consist of SCURVE, STEE, SLIN, and Term were designed and optimized to achieve an equivalent value of 78 dB for S11, S22, S33, S44, and S55 at center frequency of 2 GHz. Such consistent value between those S-parameters proven a perfect matching impedance are successfully obtained by proposed symmetric 5PR even own a bandwidth as high as 162%. Moreover, the simulated and measured results show the proposed 5PR has realized magnitude of ≈ 0 dB (S11), 0.5 (S12, S13, S14, S15, S21, S23 … S54) as well as phase relative error of 120° which in parallel to theoretical values. With all capabilities mentioned, the proposed 5PR is a promising candidate to be installed in a microwave imaging system for biomedical applications in the future. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:802–805, 2017.

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Directional and wideband antenna for ground penetrating radar (GPR) applications

2017-01-03 , Nazuhusna Khalid , Siti Zuraidah Ibrahim , Mohd Nazri A. Karim

This paper presents a directional and wideband antenna for ground penetrating radar (GPR) applications. The antenna is designed by introducing slots on bowtie patch. The design is implemented on FR4 board with dielectric constant of 4.7 and thickness of 0.8 mm. As a result of having thinner substrate, the design is compact and light weight. The bowtie antenna performance is investigated across 0.5 GHz to 3 GHz. The parametric study of the length and location of slot are also demonstrated in this paper to obtaining the best return loss across widest operational bandwidth. The both simulated and fabricated antenna bandwidth are more than 50% (fractional bandwidth). The additional reflector is included at the back of bowtie antenna in the simulation for obtaining directional radiation pattern and high gain. The comparison between simulated and measured reflection coefficient is also presented.

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Development of U-Shape Slot Wearable Antenna for In-Body Communications

2020-03-20 , Kamaruddin N.A. , Saidatul Norlyana Azemi , Siti Zuraidah Ibrahim , Mohd Rashidi Che Beson

The ability to have a communication with devices implanted inside a human body will cause a great improvement in current wireless medical applications technology. Wireless Capsule Endoscopy (WCE) is a medical device that could send images from inside of human's intestines to the sensor outside the body. However, this device has few disadvantages like its location cannot be detected once it entered the body and it also cannot be control from outside the body. Considering these factors, an antenna that has the ability to penetrate into human body tissues for in-body communication is proposed. UWB system has considered as the solution for future in-body communication devices since current standard does not allow high data rate wireless connections between implanted nodes. Low part of UWB frequency band which is 3.1 GHz to 5.0 GHz is used in this research in order to reduce the attenuation through the body tissues as the frequency increase. The design of this antenna has taken in consideration of the propagation medium which is the human body tissues. Simulation for the designed antenna was done in CST Software. The size of this antenna is designed to be compact and wearable on human body. The substrate used for this antenna is cotton to ensure comfort once it is placed on the human body. The results that are considered in this research are the S11, directivity and gain of the antenna. Both simulation results and measured results are compared to evaluate the ability of this antenna.

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Design and development of two-stage low-noise amplifier (LNA) using E-pHEMT technology for C-band application

2020 , Faaiqah Kamsaini , Mohammad Shahrazel Razalli , Siti Zuraidah Ibrahim , Mohd Zaizu Ilyas

The low-noise amplifier (LNA) is a vital part of the radio frequency (RF) transceiver system. It amplifies weak signals with minimal distortion. The LNA performance is mainly determined by its noise figure (NF), gain, and power consumption. In this paper, the design of a 6 GHz low-noise amplifier (LNA) using enhancement-mode pseudomorphic high-electron-mobility transistor (E-pHEMT) technology is presented. In order to attain high gain with low S-parameters losses, a two-stage LNA configuration with single-stub matching is devised. The same bias conditions are applied to both of the LNA stages, V DS = 2.7 V and I DS = 10 mA. The LNA design is simulated and optimised by using electromagnetic (EM) software. To further improve the overall LNA performances, high impedance inductors and series resonators are implemented into the circuit. Simulated results of the designed LNA indicate a power gain, S 21 of 25.2 dB and NF of 2.4 dB at 6 GHz with 27 mW dissipation per stage. The circuit layout is fulfilled with an E-pHEMT technology (ATF-55143) on the FR4 substrate. The LNA is powered by a 3 V DC power supply.

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Miniature microstrip bandpass filters based on quadruple-mode resonators with less via

2017-05-03 , Sugchai Tantiviwat , Mohammad Shahrazel Razalli , Siti Zuraidah Ibrahim

This article aims to design of microstrip resonators in order to reduce size of microstrip bandpass filters in wireless communication systems. Characterized by both theoritical investigation and full-wave simulation, the proposed bandpass filters are designed consist of dual-band bandpass filters and quadruple mode bandpass filters with miniaturized size. The proposed filter is found to have benefits such that the even-mode resonant frequencies can be flexibly controlled while the odd-mode resonant frequency is reserved for the fundamental frequency. Since the structure of resonators is realized using common via holes, the difficulty and complexity of the fabrication process can be shortened. In order to achieve compact size, the total number of resonators is reduced so that the implemented resonators only occupy a small area.

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IoT-based Door Access Using Three Security-Layers

2023-10-06 , Aznan M.A. , Siti Zuraidah Ibrahim , Ku Nurul Fazira Ku Azir , Ruzelita Ngadiran , Mohd Noh F.H.

This paper demonstrates an Internet-of-Things, IoT-based Door Access using three security layers, which are biometric identification, authentication, and authorized reply. The IoT-based door access is developed with Closed Circuit Television (CCTV) monitoring to control door access by authorized users using facial recognition technique and the Telegram application along with a database to record user logs. In the first security layer, the user’s face will be captured by CCTV camera and then processed to match to the registered face. In the authentication layer, the system will use Telegram Bot to send a message to the user registered Telegram Chat Identification (ID) only for entering the password. In the third security layer, if the password is valid, the system will send a signal to the hardware to unlock the door. The results showed that the developed prototype of this system successfully operated as expected.

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Design of Quad-Band Bandpass Filter Using Dual-Mode SLRs and Coupled-Line for DCS/WLAN/WiMAX and 5G Applications

2022-05-01 , Tantiviwat S. , Siti Zuraidah Ibrahim , Mohammad Shahrazel Razalli , Soh Ping Jack

A design of a microstrip quad-band BPF with flexibly controlled bandwidth is presented in this paper. Two dual-mode short-circuited SLRs with a common via-hole are proposed, which are utilized to obtain the first and second passband, while the third passband is generated by implementing the second-order half-wavelength coupled-line resonator. Another dual-mode open-circuited SLR can be operated at the fourth passband. The proposed quad-band BPF is centered at 1.80/2.45/3.50/4.90 GHz for DCS/WLAN/WiMAX and 5G applications. By appropriately choosing the lengths of the four sets of resonators, all passbands can be fully varied independently with minimal effect on other passbands. Moreover, the bandwidth of each passband can be flexibly controlled by tuning the coupling parameters. The dimension of the fabricated proposed filter is about 0.12 × 0.20 λg, indicating the compactness of the design, whereas the measurements are in good agreement with the simulated results. The measured S11 are at least 12 dB in the four pass-bands. The passbands S21 are approximately 0.65, 1.42, 0.78, and 1.20 dB, which exhibit low insertion loss at the passband frequency of the first, second, third, and fourth passband, respectively.

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Development of branchline coupler using parallel coupled transmission lines

2017-01-03 , Rahim N.H.A. , Rasid R. , Siti Zuraidah Ibrahim , Nazuhusna Khalid , Mohammad Shahrazel Razalli , Siang T.G.

This paper investigates the development of branchline coupler using parallel coupled transmission lines on planar microstrip using CST Studio Suite 2010 design tool. This project operates within 4 GHz to 8 GHz frequency band. Two designs are proposed in this project which are basic branch line coupler and branch line coupler with parallel line feeding technique. The main purpose of this study is to improve bandwidth while compare the performance of both designed coupler. The designs are then investigated using CST Microwave Studio simulation tool. The designs are fabricated on microstrip printed circuit board and measured using vector network analyzer. The simulated and experimental results of both developed couplers are compared and analyzed. The overall simulated percentage bandwidth of the proposed coupler is covered from 4 to 8 GHz with percentage bandwidth of 32.32%.

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Miniature triple-mode diplexer with good selectivity

2017-01-01 , Sugchai Tantiviwat , Siti Zuraidah Ibrahim , Mohammad Shahrazel Razalli

This paper presents a compact diplexer with high selectivity. The proposed diplexer employs two sets of triple-mode bandpass filters. Using this approach, the pair of even-mode resonant frequencies can be flexibly controlled by adjusting the characteristic impedance or electrical lengths of the two open-circuited stubs while the odd-mode resonant frequency remains at the fundamental resonant frequency. For a demonstration, a diplexer with two passbands centred at 1.50 and 1.70GHz and the transmission zeros are created close to the passband edges which extremely improve the skirt selectivity. As a result, the proposed diplexer occupies an extremely small area, i.e., approximately 0.30λg × 0.35λg. The measured results are in good agreement with the simulated predictions.

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Parametric analysis on the effect of open circuit stub resonator towards the performance of ultra-wideband stepped impedance low pass filter

2017-01-01 , Nur Baya Mohd Hashim , Mohammad Shahrazel Razalli , Mohd Zaizu Ilyas , Hasliza A Rahim @ Samsuddin , Siti Zuraidah Ibrahim

This paper presents the parametric studies on the effect of open circuit stub resonator (OCSR) towards the performance of Chebyshev Ultra-Wideband Stepped Impedance Low Pass Filter (SILPF). The SILPF is realized by loading OCSR to the high impedance line of the main design in order to overcome the drawback of conventional SILPF. The filter can produce sharp transition band and also wide stopband bandwidth. The design of SILPF is based on 5th order Chebyshev with 0.1 dB ripple. The filter is designed to operate at cut-off frequency 7.30 GHz. By investigating the effect of varying dimension of OSCR’s selected parameters, this paper is able to highlight the susceptibility of modifying cut-off frequency, fc and also transmission zeroes frequency, fz in order to be used for different applications. Thus, the combination of SILPF and OCSR and also rectangular patch combined feed-line structure exhibits wide rejection bandwidth better than −20 dB from 8.20 GHz up to 23.38 GHz. The filter design is simulated on Roger 4003 with relative dielectric constant, εr of 3.38 and also the substrate thickness, h of 0.508. This proposed simulated filter design has shown promising result and could be further analyzed for experimental works and fabrication. Therefore, the filter is beneficial for communication and radar systems particularly to avoid the interference and harmonic as well as the spurious response signals.

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