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

Research Output

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  • Publication
    Signal propagation analysis for low data rate wireless sensor network applications in sport grounds and on roads
    ( 2012)
    David L. Ndzi
    ;
    M. A. Mohd Arif
    ;
    Ali Yeon Md Shakaff
    ;
    Mohd Noor Ahmad
    ;
    Azizi Harun
    ;
    Latifah Munirah Kamarudin
    ;
    Ammar Zakaria
    ;
    Mohd F. Ramli
    ;
    Mohammad Shahrazel Razalli
    This paper presents results of a study to characterise wire- less point-to-point channel for wireless sensor networks applications in sport hard court arenas, grass fields and on roads. Antenna height and orientation effects on coverage are also studied and results show that for omni-directional patch antenna, node range is reduced by a factor of 2 when the antenna orientation is changed from vertical to horizontal. The maximum range for a wireless node on a hard court sport arena has been determined to be 70m for 0dBm transmission but this reduces to 60m on a road surface and to 50m on a grass field. For horizontal antenna orientation the range on the road is longer than on the sport court which shows that scattered signal components from the rougher road surface combine to extend the communication range. The channels investigated showed that packet error ratio (PER) is dominated by large-scale, rather than small-scale, channel fading with an abrupt transition from low PER to 100% PER. Results also show that large-scale received signal power can be modeled with a 2nd or der log-distance polynomial equation on the sport court and road, but a 1st order model is sufficient for the grassfield. Small-scale signal variations have been found to have a Rice distribution for signal to noise ratio levels greater than 10 dB but the Rice K-factor exhibits significant variations at short distances which can be attributed to the influence of strong ground reflections.
  • Publication
    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.
  • 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
    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%.
  • Publication
    Tuneable dual-mode narrowband bandstop filter using loaded microstrip resonator
    ( 2017-01-03)
    Farah Shazuani Mahmud
    ;
    Mohammad Shahrazel Razalli
    ;
    Wee Fwen Hoon
    ;
    Siti Zuraidah Ibrahim
    ;
    Nur Baya Mohd Hashim
    Novel tuneable dual-mode narrowband bandstop filter using loaded microstrip resonator is presented. The filter is designed by using coupled line coupling with the microstrip resonator. There is two different pair of loaded resonator that produces a dual band bandstop filter. The dual band bandstop resonance frequency can be tuned independently by adjusting the resonator width and length. To achieve high selectivity of the bandstop filter response, defected ground structure (DGS) is applied in the filter layout. The tapped lines structure (TLS) are used to suppress second harmonic frequency. The dual band bandstop filter is resonant at 2.4 GHz with 200 MHz of bandwidth and 5.8 GHz with 300 MHz of bandwidth. The bandstop filter layout is fabricated on RO 4003C with 0.508 mm of substrate thickness. It is compact dimension with 19.6mm × 38.8mm. The advantages of this bandstop filter are simple layout and it can be tuned to the specified frequencies.
  • 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
    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.
  • Publication
    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.
  • Publication
    Comparison of rectifier performance using different matching technique
    ( 2017-01-03)
    Ismahayati Adam
    ;
    Mohd Najib Mohd Yasin
    ;
    Mohammad Shahrazel Razalli
    This paper describes the design and implementation of the 4-stage Villard multiplier for RF energy harvesting. Each stage is a combination of two HSMS 2850 Schottky diodes and two capacitors for each stage. For ambient energy harvesting, the incident power is extremely small, thus an efficient rectifier is needed. The designed rectifier with the matching circuit is a good candidate since it is able to enhance the rectified output power up to 300% during -40dBm input power compared to the rectifier circuit alone.
  • Publication
    Compact low pass filter with deep and wide stopband using H-shaped defected microstrip structure
    ( 2017-01-03)
    Nur Baya Mohd Hashim
    ;
    Mohammad Shahrazel Razalli
    ;
    Siti Zuraidah Ibrahim
    ;
    Farah Shazuani Mahmu
    ;
    Nordiana Mohamad Saaid
    A deep attenuation level and wide stopband bandwidth, sharp roll-off and low insertion loss in the passband using H-shaped defected microstrip structure (DMS) at open circuit stub resonator (OCSR) of the stepped-impedance low pass filter (SILPF) is presented in this paper. The proposed filter consists of H-shaped that is etching at the microstrip line of OCSR. The OCSR is embedded in the middle of high impedance line of the SILPF. The effect of the applying H-shaped DMS is investigated through parametric studies by comparing H-shaped with Y-shaped and U-shaped. It is observed that the comparison with conventional SILPF shows that the proposed modification filter exhibit a deep and large rejected band of 27 dB attenuation level from 8.21 GHz to 23.16 GHz up to 3 fc. The proposed filter also offers sharp roll-off at 7.31 GHz cut-off frequency and maximum ripple value in the range of DC to 6 GHz is less than 0.35 dB.