Mohd Najib Mohd Yasin
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Preferred name
Mohd Najib Mohd Yasin
Official Name
Mohd Najib , Mohd Yasin
Alternative Name
M. Yasin, M. Najib
Yasin, Mohd Najib
Yasin, Mohd Najib M.
Yasin, M. N.Mohd
Mohd Yasin, M. N.
Main Affiliation
Scopus Author ID
57210314287
Researcher ID
AAQ-6242-2021

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Size-Reduction of a Dual-Band Circularly Polarized Dielectric Resonator Antennas

2021-01-01 , Mohd Najib Mohd Yasin , Ali A. , Zambak M.F. , Radzi M.F.

In this paper, a circularly polarized rectangular DRA has been designed and simulated for WiMAX, satellite, 5G NR band applications. The design uses an F-shaped conducting patch with a parasitic patch to excite the design. The bandwidth enhancement of the design has been achieved thorough the optimization of the patch placement and gap distance for both conducting patch and parasitic patch to cover the desired operating frequency. The S11<10 dB and axial ratio< -3 dB result covers the operating frequency range. The designing and optimization of the design has been carried out using the CST Studio Suite software.

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Modeling superconducting critical temperature of 122-iron-based pnictide intermetallic superconductor using a hybrid intelligent computational method

2021-08-02 , Akomolafe O. , Owolabi T.O. , Rahman M.A.A. , Kechik M.M.A. , Mohd Najib Mohd Yasin , Souiyah M.

Structural transformation and magnetic ordering interplays for emergence as well as suppression of superconductivity in 122-iron-based superconducting materials. Electron and hole doping play a vital role in structural transition and magnetism suppression and ultimately enhance the room pressure superconducting critical temperature of the compound. This work models the superconducting critical temperature of 122-iron-based superconductor using tetragonal to orthorhombic lattice (LAT) structural transformation during low-temperature cooling and ionic radii of the dopants as descriptors through hybridization of support vector regression (SVR) intelligent algorithm with particle swarm (PS) parameter optimization method. The developed PS-SVR-RAD model, which utilizes ionic radii (RAD) and the concentrations of dopants as descriptors, shows better performance over the developed PS-SVR-LAT model that employs lattice parameters emanated from structural transformation as descriptors. Using the root mean square error (RMSE), coefficient of correlation (CC) and mean absolute error as performance measuring criteria, the developed PS-SVR-RAD model performs better than the PS-SVR-LAT model with performance improvement of 15.28, 7.62 and 72.12%, on the basis of RMSE, CC and Mean Absolute Error (MAE), respectively. Among the merits of the developed PS-SVR-RAD model over the PS-SVR-LAT model is the possibility of electrons and holes doping from four different dopants, better performance and ease of model development at relatively low cost since the descriptors are easily fetched ionic radii. The developed intelligent models in this work would definitely facilitate quick and precise determination of critical transition temperature of 122-iron-based superconductor for desired applications at low cost with experimental stress circumvention.

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A novel unsupervised spectral clustering for pure-tone audiograms towards hearing aid filter bank design and initial configurations

2022-01-01 , Elkhouly A. , Allan Melvin Andrew , Hasliza A Rahim @ Samsuddin , Abdulaziz N. , Abdulmalek M. , Mohd Najib Mohd Yasin , Muzammil Jusoh , Thennarasan Sabapathy , Siddique S.

The current practice of adjusting hearing aids (HA) is tiring and time-consuming for both patients and audiologists. Of hearing-impaired people, 40–50% are not satisfied with their HAs. In addition, good designs of HAs are often avoided since the process of fitting them is exhausting. To improve the fitting process, a machine learning (ML) unsupervised approach is proposed to cluster the pure-tone audiograms (PTA). This work applies the spectral clustering (SP) approach to group audiograms according to their similarity in shape. Different SP approaches are tested for best results and these approaches were evaluated by Silhouette, Calinski-Harabasz, and Davies-Bouldin criteria values. Kutools for Excel add-in is used to generate audiograms’ population, annotated using the results from SP, and different criteria values are used to evaluate population clusters. Finally, these clusters are mapped to a standard set of audiograms used in HA characterization. The results indicated that grouping the data in 8 groups or 10 results in ones with high evaluation criteria. The evaluation for population audiograms clusters shows good performance, as it resulted in a Silhouette coefficient >0.5. This work introduces a new concept to classify audiograms using an ML algorithm according to the audiograms’ similarity in shape.

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Microwave and electrical properties of SrTiO3 for DRA application

2018-12 , Norhizatol Fashren Muhamad , Rozana Aina Maulat Osman , Mohd Sobri Idris , Mohd Najib Mohd Yasin , Mohd Faizal Jamlos , Nor Azura Malini Ahmad Hambali , Mohd Nazree Derman

Appropriate level of dielectric constant and low dielectric loss are basic requirements for microwave device, especially in dielectric resonator antenna (DRA). In this paper, investigation with experimental studies of SrTiO₃ ceramic fabricated as cylindrical dielectric resonator antennas (CDRAs) was conducted. Ceramic powder was prepared using conventional solid state reaction method. X-ray Diffraction exposes physical properties SrTiO₃ which exhibit cubic structure. The electrical properties such as dielectric constant (εᵣ) and dielectric loss (tan δ) were studied in variation of temperatures and frequencies. At room temperature the dielectric constant SrTiO₃ is about 240. The dielectric loss obtain shows very low loss value roughly below 0.07. The return loss and bandwidth of CDRAs at their respective resonant frequencies are shown in this paper.

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Essential semiconductor films in micro-/nano-biosensors: Current scenarios

2021-10-01 , Subash Chandra Bose Gopinath , Ramanathan S. , Mohd Najib Mohd Yasin , Shapiai M.I. , Ismail Z.H. , Subramaniam S.

Background: Engineering nanoscale matter in a controlled functional system has expanded the area of science in the state-of-art of nanotechnology. The urgency in introducing real-time health monitoring sensors and rapid diagnostic tools in medical health is indeed high and crucial to date. The efforts are accompanied by nanotechnology to improve the sensors performances. In this line, semiconductor materials (Silicon/Silica) have been in well-focus to develop micro-/nano-sensors. Methods: Further, additional layering such as metal oxide and graphene material have elevated the current scenario in biosensor developments. Among these, two-dimensional graphene nanomaterial owns its remarkable mechanical, electronic, electrochemical, and optical properties, has excited the medical field to develop graphene-based biosensors for human health diagnosis and monitoring. The oxygen rich graphene materials enhance the bio-functionalization of recognition bio-elements for excellent graphene-based biosensor development. Significance: This review encloses the excellence of semiconductor materials in conjunction with biosensors for monitoring health and diagnosis. The advances and challenges encountered with developing semiconductors for nanobiosensors from laboratory set-up to the novel hand-held device for rapid and accurate human health care are outlined.

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Design of Reconfigurable Antenna for RFID System

2021-07-26 , Renukka Sivakumar , Thennarasan Sabapathy , Muzammil Jusoh , Soh Ping Jack , Mohamed Nasrun Osman , Salem Al-Bawri S. , Jayaprakasam S. , Mohd Najib Mohd Yasin , Saluja N.

This paper proposes a reconfigurable antenna for RFID system which can operate between 860MHz to 960MHz frequency that belongs to ultra-high frequency (UHF) band used in Malaysia with the center frequency of 910MHz. One rectangular slot and two triangle-shaped slots are used in designing this antenna. A good circular polarization obtained from the slotted structure along the diagonal axis in the design. RF pin diodes are used as the switching mechanism of the antenna. However, in this work to proof the concept of switching mechanism, copper pins are used as artificial switches. Parasitic elements are deployed on the right and left side of the driven element to assist the radiation pattern reconfiguration. Overall, the proposed antenna able to steer the beam at approximately at -30 , -16 , and 10 with peak gain of 3.2dB and average gain of 2.5dB. With this result, overall coverage of UHF RFID reader antenna could be improved.

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Advancement in biosensor: “Telediagnosis” and “remote digital imaging”

2022-06-01 , Subash Chandra Bose Gopinath , Ismail Z.H. , Shapiai M.I. , Mohd Najib Mohd Yasin

Current developments in sensors and actuators are heralding a new era to facilitate things to happen effortlessly and efficiently with proper communication. On the other hand, Internet of Things (IoT) has been boomed up with er potential and occupies a wide range of disciplines. This study has choreographed to design of an algorithm and a smart data-processing scheme to implement the obtained data from the sensing system to transmit to the receivers. Technically, it is called “telediagnosis” and “remote digital monitoring,” a revolution in the field of medicine and artificial intelligence. For the proof of concept, an algorithmic approach has been implemented for telediagnosis with one of the degenerative diseases, that is, Parkinson's disease. Using the data acquired from an improved interdigitated electrode, sensing surface was evaluated with the attained sensitivity of 100 fM (n = 3), and the limit of detection was calculated with the linear regression value coefficient. By the designed algorithm and data processing with the assistance of IoT, further validation was performed and attested the coordination. This proven concept can be ideally used with all sensing strategies for immediate telemedicine by end-to-end communications.

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The design of wideband circularly polarized hemispherical DRA using conformal open halfloop excitation

2017-12-15 , Mohamad Ismail Sulaiman , Mohd Najib Mohd Yasin , Hafiz Basarudin , Aizat Faiz Ramli , Mohd Azlan Abu

A circularly polarized (CP) hollow hemispherical dielectric resonator antenna (DRA) is presented. The CP DRA that is excited using conformal open half loop metal strips has been studied theoretically and experimentally. The proposed antenna configuration has provided a measured CP and return loss bandwidths of ∼11.i5%, and 10.32% respectively. The DRA has been simulated using Method of Moments (MoM) model, where a good agreement has been obtained between the experimental and theoretical results.

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Design of 1 × 2 MIMO Palm Tree Coplanar Vivaldi Antenna in the E-Plane with Different Patch Structure

2023-01-01 , Nurhayati N. , Setijadi E. , de Oliveira A.M. , Kurniawan D. , Mohd Najib Mohd Yasin

In this paper, 1 × 2 MIMO of Palm Tree Coplanar Vivaldi Antenna is presented that simulated at 0.5–4.5 GHz. Some GPR applications require wideband antennas starting from a frequency below 1 GHz to overcome high material loss and achieve deeper penetration. However, to boost the gain, antennas are set up in MIMO and this is costly due to the large size of the antenna. When configuring MIMO antenna in the E-plane, there is occasionally uncertainty over which antenna model may provide the optimum performance in terms of return loss, mutual coupling, directivity, beam squint, beam width, and surface current using a given substrate size. However, the configuration of E-plane antenna in MIMO has an issue of mutual coupling if the distance between elements is less than 0.5λ. Furthermore, it produces grating lobes at high frequencies.We implement several types of patch structures by incorporating the truncated, tilt shape, Hlbert and Koch Fractal, Exponential slot, Wave slot, the lens with elips, and metamaterial slot to the radiator by keeping the width of the substrate and the shape of the feeder. The return loss, mutual coupling, directivity, beam squint, beamwidth, and surface current of the antenna are compared for 1 × 2 MIMO CVA. A continuous patch MIMO has a spacing of 0.458λ at 0.5 GHz, which is equivalent to its element width. From the simulation, we found that Back Cut Palm Tree (BCPT) and Horizontale Wave Structure Palm Tree (HWSPT) got the best performance of return loss and mutual scattering at low-end frequency respectively. The improvement of directivity got for Metamaterial Lens Palm Tree (MLPT) of 4.453 dBi if compared with Regular Palm Tree-Coplanar Vivaldi Antena (RPT) at 4 GHz. Elips Lens Palm Tree (ELPT) has the best beam squint performance across all frequencies of 0°. It also gots the best beamwidth at 4.5 GHz of 3.320. In addition, we incorporate the MLPT into the radar application.

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A 0.7 GHz and 0.9 GHz efficient and compact dual-band rectifier for ambient radio frequency energy harvesting

2025 , Raja Nor Azrin Raja Yunus , Ismahayati Adam , Mohd Najib Mohd Yasin , Surajo Muhammad , Abdulrahman Amin Ahmed Ghaleb , Wan Zuki Azman Wan Muhamad

This study introduces a compact dual-band rectifier utilizing a single and multi-stub matching network (MN) technique. The rectifier consists of two branches, each incorporating a single block stub and two blocks stub to generate two frequency susceptance blocks, subsequently transformed into a meandered line. The proposed rectifier operates at two frequency bands of 0.7 GHz and 0.9 GHz and is fabricated on an RT/Duroid 5880 printed circuit board (PCB) with dimensions of 37×25×1.6 mm using an entire ground architecture. Simulation and measurement results show that the rectifier has a power conversion efficiency (PCE) of 67.77% and 66.35% at 0.7 GHz and 70.31% and 71.22% at 0.9 GHz with input power of 0 dBm, respectively. The rectified voltage is 1.79 V DC across a 5 kΩ load terminal (RL) with 5 dBm input power and is capable of sensing low input power down to -30 dBm. This feature makes the rectifier a promising solution for powering low-power devices from ambient energy.

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