Mohammad Shahrazel Razalli
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Preferred name
Mohammad Shahrazel Razalli
Official Name
Mohammad Shahrazel , Razalli
Alternative Name
Razalli, Mohd Shahrazel
Razalli, Mohamad Shahrazel
Razalli, Mohammad S.
Razalli, M. S.
Main Affiliation
Scopus Author ID
24825300000
Researcher ID
FUH-9138-2022

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  • Publication
    Parametric studies on effects of defected ground structure (DGS) for dual band bandstop microstrip filter
    ( 2017-11-22)
    Farah Shazuani Mahmud
    ;
    Mohammad Shahrazel Razalli
    ;
    Hasliza A Rahim @ Samsuddin
    ;
    Wee Fwen Hoon
    ;
    Mohd Zaizu Ilyas
    A dual-band bandstop microstrip filter is proposed and designed by using microstrip resonator with Defected Ground Structure (DGS). The DGS are placed in the ground plane to obtain high attenuation of the bandstop filter response. The proposed is designed by using R04003C printed circuit board with dimension of 38 mm x 20 mm. Simulated result shows an insertion loss of -12.31 dB, a return loss at -1.75 dB for center frequency at 2.4 GHz and insertion loss of -22.93 dB, a return loss of -0.78 dB for center frequency at 5.8 GHz The results of simulated in different parameters of DGS is analysed and discussed.
  • Publication
    The Performance Analysis of K-Nearest Neighbors (K-NN) Algorithm for Motor Imagery Classification Based on EEG Signal
    ( 2017-12-11)
    Nurul E’zzati Md Isa
    ;
    Amiza Amir
    ;
    Mohd Zaizu Ilyas
    ;
    Mohammad Shahrazel Razalli
    Most EEG-based motor imagery classification research focuses on the feature extraction phase of machine learning, neglecting the crucial part for accurate classification which is the classification. In contrast, this paper concentrates on the classifier development where it thoroughly studies the performance analysis of k-Nearest Neighbour (k-NN) classifier on EEG data. In the literature, the Euclidean distance metric is routinely applied for EEG data classification. However, no thorough study has been conducted to evaluate the effect of other distance metrics to the classification accuracy. Therefore, this paper studies the effectiveness of five distance metrics of k-NN: Manhattan, Euclidean, Minkowski, Chebychev and Hamming. The experiment shows that the distance computations that provides the highest classification accuracy is the Minkowski distance with 70.08%. Hence, this demonstrates the significant effect of distance metrics to the k-NN accuracy where the Minknowski distance gives higher accuracy compared to the Euclidean. Our result also shows that the accuracy of k-NN is comparable to Support Vector Machine (SVM) with lower complexity for EEG classification.
  • Publication
    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.
  • Publication
    Design of C-band Low-noise Amplifier (LNA) Using E-pHEMT Device for Satellite Communication System
    ( 2020-03-20)
    Kamsaini F.
    ;
    Mohammad Shahrazel Razalli
    ;
    Siti Zuraidah Ibrahim
    ;
    Mohd Zaizu Ilyas
    A low-noise amplifier (LNA) plays an indispensable role in a communication system for amplification purposes at the transceiver. LNA design in radio frequency (RF) circuits involve various key attributes, namely noise figure (NF), gain, and power consumption. This paper focuses on the design of a C-band LNA for satellite communication system with a centre frequency of 6 GHz using ATF-55143 enhancement-mode pseudomorphic high-electron-mobility transistor (E-pHEMT) technology. The LNA performance is augmented by adding inductors to the drain and gate of the ATF-55143 transistor. Smith chart impedance matching technique is implemented to foster a more precise matching for input and output of the LNA. In this work, the C-band LNA is biased at VDS of 2.7 V and IDS of 10 mA. Electromagnetic (EM) software is used to design and simulate the performance of the LNA circuit layout. Simulation results indicate NF of 2.66 dB and power gain (S21) of 12.29 dB. The LNA consumes 27 mW from a 3 V DC supply.
  • Publication
    Design and development of two-stage low-noise amplifier (LNA) using E-pHEMT technology for C-band application
    (IOP Publishing, 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.