Papers by Badrul Hisham Ahmad
Miniaturized Cupcake Fractal Patch Antenna for Biomedical Applications
2019 International Conference on Communication and Electronics Systems (ICCES)
Implantable antennas for biomedical applications are on leading edge of research for medical diag... more Implantable antennas for biomedical applications are on leading edge of research for medical diagnosis such as glucose monitoring, tracking, pacemaker etc. Biomedical applications require antennas that are very small in size but can meet designated requirements. In this paper a 24mm x 34 mm cupcake shape fractal patch antenna is designed and simulated using CST software. The designed antenna operates in 2.45 GHz frequency band called industrial, scientific and medical band (ISM band). Designed antenna's reflection coefficient, VSWR, surface current, gain and far-field plot are simulated and observed. The designed antenna provides 670 MHz (27%) bandwidth in the band of 2.20 - 2.87 GHz. This antenna is miniaturized and compacted to be utilized as an implantable antenna for biomedical applications.
Wireless communication system is a system that transfer information among two or more points that... more Wireless communication system is a system that transfer information among two or more points that are not connected by an electrical conductor while microwave filter is the elementary element in each radio frequency (RF) front-end telecommunication structure, moreover as band reject or band select components for transceivers and receivers. In designing a complicated wireless communication system or any other system that is working at microwave frequencies, noise is one of the big challenges. One of the techniques that can be used to avoid noise, or any other interference signal is by applying filtering techniques. For microwave communication front-end system, a band-stop filter can separate frequency band positioned inside a wideranging pass-band. Firstly, a single-band matched band-stop filter using T-shape resonator. Two different design had been done at 1.0 GHz and 1.5 GHz with S21 center frequency at – 16.063 dB and – 14.059 dB, respectively. Then, the combination of the multiba...
Journal of Telecommunication, Electronic and Computer Engineering, 2017
In this paper, six different bandstop filter designs using Substrate Integrated Waveguide (SIW) r... more In this paper, six different bandstop filter designs using Substrate Integrated Waveguide (SIW) resonator coupled to microstrip transmission line is presented. A curved and rectangular SIW resonator was designed and then coupled to microstrip transmission line to provide a band reject response in Advanced Design System Momentum RF software. These filters were designed for interference suppression in X-band and simulated on Rogers RO4350 substrate with thickness of 0.508 mm and relative dielectric constant of 3.48. The simulated result was compared with other bandstop filter at X-band and showed a good suppression at 9 GHz region with attenuation of -61.9 dB and -3 dB bandwidth of 90 MHz.
High Isolation of Single Pole Single Throw Switch using Defected Ground Structure
16 Retrieval Number: A1335034115/2014©BEIESP Published By: Blue Eyes Intelligence Engineering &am... more 16 Retrieval Number: A1335034115/2014©BEIESP Published By: Blue Eyes Intelligence Engineering & Sciences Publication Abstract— In this paper, a high isolation of Single Pole Single Throw (SPST) switch using Defected Ground Structure (DGS) is proposed. A discrete PIN diode was used as switching element in the SPST switch design. First, the resonant frequency of the discrete PIN diode on DGS, which is based on mathematical modeling and circuit simulation is analyzed. The results showed that the resonant frequency of the discrete PIN diode on the DGS was shifted to higher frequency during ON state and was shifted to lower frequency during OFF state. Then, by realizing the SPST switch circuit using FR4 substrate in 1.5 GHz frequency band, the measured result clearly showed that high isolation (>30 dB) of the proposed SPST switch during OFF state was produced by using DGS compared to a SPST switch without DGS.
The Influence of Innovation Characteristics on Low Loss Microwave Transmission Glass Adoption: A Conceptual Paper
GATR Global Journal of Business Social Sciences Review
Objective - Based on theoretical considerations, this paper focuses on (1) the adoption level of ... more Objective - Based on theoretical considerations, this paper focuses on (1) the adoption level of Low Loss Microwave Transmission Glass (LLMTG), which encompasses as new innovation among users in Malaysia and (2) investigates the influences of innovation characteristics towards low loss microwave transmission glass (LLMTG). Methodology/Technique - This study seeks to determine the adoption level of innovations by these five key innovation characteristics: 1. relative advantage, 2. compatibility, 3. complexity, 4. observability, and 5. trialability to understand more about important factors when adopting LLMTG. This paper has developed a conceptual model of innovation characteristics by Roger's theory to be tested in the adoption of LLMTG. Findings - This conceptual study expected all factors will be associated positively to LLMTG adoption, except complexity. Novelty - This paper is the first study in Malaysia, which differentiate between energy saving glass (ESG) and low loss mic...
Journal of Telecommunication, Electronic and Computer Engineering, 2017
In this project, different locations of the Minkowski Island split ring resonator (MI-SRR) struct... more In this project, different locations of the Minkowski Island split ring resonator (MI-SRR) structure are embedded in the basic rectangular patch antenna. It started with a basic rectangular microstrip patch antenna that were simulated in CST Microwave Studio software. After that, four different locations (Location A, Location B, Location C and Location D) of MI-SRR were chosen to compare the performance of return loss, resonant frequency, surface current radiation pattern, and gain. Location A represented the antenna with the MI-SRR at the center part of the patch, while Location B had the MI-SRR at the upper part of the FR-4 substrate. Location C and Location D represented the antenna with MI-SRR at the ground at antenna with MI-SRR at the other layer, respectively. The return loss performances of Design of Location A, Location B, Location C, and Location D were - 26.546 dB, - 23.892 dB, -43.842 dB, - 51.506 dB at resonant frequency of 2.432 GHz, 2.510 GHz, 2.438 GHz and 2.542 GHz,...
Journal of Telecommunication, Electronic and Computer Engineering, 2017
This paper presents the design of a circular loop for Frequency Selective Surfaces (FSS) based on... more This paper presents the design of a circular loop for Frequency Selective Surfaces (FSS) based on complementary techniques for 2.4GHz application. The design of circular loop FSS is simulated using CST Microwave Studio software. The simulation process is based on the characteristics of the reflection coefficient (S11) and transmission coefficient (S21) of the FSS. In this paper, there are two designs that have been presented, namely Design A, which is double circle loop in horizontal axes and Design B is double circle loop in horizontal axes using complementary techniques. It was found that the best performance of the FSS is Design B in terms of return loss and bandwidth. The return loss for Design B is -29.13dB and the bandwidth is 0.39211 GHz at a frequency range from 2.2012 GHz to 2.5933 GHz.
Computers, Materials & Continua, 2022
In this paper, a high gain and directional coplanar waveguide (CPW)fed ultra-wideband (UWB) plana... more In this paper, a high gain and directional coplanar waveguide (CPW)fed ultra-wideband (UWB) planar antenna with a new frequency selective surface (FSS) unit cells design is proposed for UWB applications. The proposed UWB antenna was designed based on the Mercedes artistic-shaped planar (MAP) antenna. The antenna consisted of a circular ring embedded with three straight legs for antenna impedance bandwidth improvement. The modelled FSS used the integration of a two parallel conductive metallic patch with a circular loop structure. The FSS provided a UWB stopband filter response covering a bandwidth of 10.5 GHz, for frequencies from 2.2 to 12.7 GHz. The proposed FSS had a compact physical dimension of 5 mm × 5 mm × 1.6 mm, with a printed array of 19 × 19 FSS unit cells. The FSS unit cells were printed on only one side of the dielectric FR4 substrate and placed as a sandwich between the antenna and the reflector ground plane. An equivalent circuit configuration (ECC) was used to verify the FSS unit cell structure's performance. The simulated results indicated that the UWB MAP antenna and FSS reflector provided a fractional bandwidth of 136% and a high gain of 11.5 dB at 8.5 GHz with an acceptable radiation efficiency of 89%. Furthermore, the gain was improved across the operating band and kept between 8.3 and 11.5 dB. The proposed antenna was in good agreement between theoretical and experimental results and offered a wide enough bandwidth for UWB and vehicle applications.
The development in technologies has taken place in many sectors such as the Wearable Health Monit... more The development in technologies has taken place in many sectors such as the Wearable Health Monitoring System (WHMS). It hasbeen a remarkable revolution by the emerging of the Wireless Sensor Network (WSN) in performing the monitoring and recording of healthcare. Thus, the wearable wireless sensor based systems are intended to provide better personal health management, ubiquitous monitoring health condition, better quality treatment and care, along with to allow efficient circuit integrations, reliable vital signal measurements, low operation costs and optimum power usage. This paper therefore attempts to comprehensively review the basic concepts of Wearable Health Monitoring System (WHMS) using Wireless Sensor Network (WSN). A comparative study was carried out in various healthcare monitoring systems, which adapted different wireless technology. In addition, the challenges and limitations of WHMS systems are identified. The implication of this study is to minimize the challenges and limitations in the design, development and application of a wearable wireless sensor based systems. It is expected in the future that the information shared in this paper can serve similar scientific field and improve the system features.
In this paper, two common techniques indesigning microstrip microwave filterwere reviewed which a... more In this paper, two common techniques indesigning microstrip microwave filterwere reviewed which areperiodic and non-periodic microstrip line perturbation techniques and matched filter. This technique are widely used in RF microstrip designs such asPhotonic Band Gap (PBG), Defected Ground Structure (DGS), Defected Microstrip Structure (DMS), Ground Plane Aperture (GPA), Electromagnetic Band Gap (EBG), high-impedance surface (HIPs), and uniplanar compact photonic bandgap (UC-PBG), distorted UC-PBG (DUC-PBG), dual-mode ring resonator, and Multi-Band Matched Bandstop Filter Design.
Fork-like shaped monopole antenna with defected parasitic elements and ring slots
2014 IEEE International Conference on Control System, Computing and Engineering (ICCSCE 2014), 2014
This work investigate the effect of the defected parasitic element and ring slot on the ground pl... more This work investigate the effect of the defected parasitic element and ring slot on the ground plane at the fork-like shape monopole antenna. Firstly, the basic fork-like shape antenna with a slot and parasitic patch had been designed in the CST Microwave Studio. Then, this antenna had been improved by embedded some defected structure in stage by stage at the ground plane - Design B, Design C, and Design D. The structure had been apply is the parasitic patch and ring slot. The optimal result of this dual-band antenna for Design D is 2.45 GHz and 5.22 GHz with a gain of 4.043 dB and 3.496 dB and the return loss of - 34.875 dB and - 18.03 dB. The target application for this antenna is at 2.45 GHz and 5.2 GHz of the frequency band.
Monopole antenna with slot SRR on hybrid material
2014 IEEE International Conference on Control System, Computing and Engineering (ICCSCE 2014), 2014
This paper investigates the effect of SRR slot on a monopole antenna with hybrid substrates. The ... more This paper investigates the effect of SRR slot on a monopole antenna with hybrid substrates. The antenna has been investigated by varying the position and the number of SRR slot. The antenna is designed by using a hybrid material substrate constructed by material FR4 and RO3006. The dielectric constant and thickness of both materials are 4.4 and 1.6mm respectively for the former as well as 6.15 and 1.28mm for the latter. The investigation has shown the ability of frequency shifting by performing horizontally shifting of SRR slot and increment of SRR slot. Besides that, increment of SRR slot has also brought to the bandwidth, gain, and efficiency enhancement.
Dual layer rectangular microstrip patch antenna with H-slot for 2.4 GHz range applications
2013 3rd International Conference on Instrumentation, Communications, Information Technology and Biomedical Engineering (ICICI-BME), 2013
ABSTRACT In this work, a dual layer rectangular microstrip patch antenna with H-slot is proposed ... more ABSTRACT In this work, a dual layer rectangular microstrip patch antenna with H-slot is proposed for improving the return loss and enhanced gain at 2.4 GHz and 2.45 GHz. The antenna is designed by using CST Microwave Studio is used to design the mathematically based on the rectangular microstrip patch antenna. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the RFID frequency range. It is found that this antenna shows − 18.584 dB at 2.45 GHz and − 19.692 dB at the resonant frequency of 2.442 GHz. At desired along this frequency band, the gain 2.228 dB at 2.442 GHz and 2.756 dB at 2.45 GHz is achieved.
Tri-polarized Patch Antenna with X-Shaped Element for Wireless LAN MIMO System
2018 IEEE International RF and Microwave Conference (RFM), 2018
In this paper, a tri-polarized antenna is with X-shaped element for multiple-input multiple-outpu... more In this paper, a tri-polarized antenna is with X-shaped element for multiple-input multiple-output (MIMO) wireless communication system had been design in CST Microwave Studio and fabricated in the laboratory. This antenna had three different stage of Antenna Design A, Antenna Design B and Antenna Design C. The first stage consists of Antenna Design A1, Design A2 and Design A3 that created to produce single polarization at frequency 2.4 GHz. Then, the Antenna Design B is then made up by joining Antenna Design A1 and Antenna Design A2 in a same antenna structure. The last stage is Antenna Design C that consist three different design - Antenna Design C1, Design C2 and Design C3. These antennas consist three different ports – Port 1, Port 2 and Port 3 that effect tri- polarized antenna. At the Port 3 of Antenna Design C3, the return loss performance of simulation and measurement of the antenna are 2.412 GHz and 2.48 GHz with −23.205 dB and −10.101 dB, respectively.
In this paper, the comparative study of switchable bandstop to bandpass (or bandpass to bandstop)... more In this paper, the comparative study of switchable bandstop to bandpass (or bandpass to bandstop) are presented. It shows that by using microstrip technology, high-Q bandstop to bandpass responses is difficult to achieve. Therefore, this paper proposes a new technique of matched bandstop to bandpass filter using two lossy low-Q resonators. The proposed technique is implemented based on perfectly-matched bandstop topology which is not only produced high-Q bandstop filter, but also easy to switch from bandstop to bandpass response. The PIN diodes (as switching element) that used in this proposed technique are incorporated into the topology to exhibit either matched bandstop response or bandpass response by turning “ON” and “OFF” of the PIN diodes. The proposed technique based on simulation result was carried out. As a result, it was found that the proposed technique was able to switch the microstrip filter from matched bandstop to bandpass filter using two lossy low-Q resonators.
Design of Wideband Monopole Antenna with CPW Feeding Technique
A critical review on electrostatic precipitator (ESP) devices in various sectors
Los precipitadores electrostaticos (ESP) son un dispositivo importante para controlar problemas a... more Los precipitadores electrostaticos (ESP) son un dispositivo importante para controlar problemas ambientales. Debido a los problemas crecientes de los problemas ambientales y de salud, un precipitador electrostatico no solo se usa ampliamente en un campo industrial, sino que tambien es importante para diversos campos y uso diario. En este estudio de investigacion, se describen las comparaciones basadas en el diseno tecnico de ESP. El analisis general del diseno tecnico de ESP se incluye con el principio de funcionamiento, los componentes utilizados, el funcionamiento, la etapa utilizada y el tipo de ESP, placa plana, tubular o tubular y tipo ESP seco o humedo. Segun la investigacion, la eficiencia de recoleccion para el ESP puede eliminar las particulas alrededor del 90%. Finalmente, las ventajas y desventajas de ESP tambien se han registrado en esta investigacion. El objetivo de este articulo de revision es hacer una comparacion de los disenos tecnicos de ESP en varios campos, como ...
A modified antipodal Vivaldi antenna (AVA) with elliptical slotting edge (ESE) for ultra-wideband (UWB) applications
2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL), 2017
As the demand of UWB system increases nowadays, several types of hybrid technique on antenna desi... more As the demand of UWB system increases nowadays, several types of hybrid technique on antenna design are studied, modified, and proposed for UWB applications. In this work, an enhanced performance of modified antipodal Vivaldi antenna (AVA) for targeting ultra-wideband (UWB) frequency range between 2.17 GHz and 10.6 GHz has been proposed. This proposed UWB antenna is using FR-4 substrate with dielectric constant, εr = 4.4 and the electrical conductivity tangent loss, tanΔ = 0.019. This antenna design is based on the modified from the dual exponential tapered slot antenna (DETSA) with varying of the exponential flares design for obtain the best return loss of the antenna within the frequency bandwidth of the UWB. It has two exponential flares that follow the characteristic of exponential curve. Next, an elliptical slotting edge (ESE) with fixed horizontal radius and varied vertical radius is implemented to the antenna which effectively increases the performance of the antenna at lower...
Comparison of Electronically Switchable High Q Bandstop to Bandpass Filters Based on Allpass Network
2021 IEEE Symposium on Wireless Technology & Applications (ISWTA), 2021
Filters are the basic component of transmitter and receiver in the microwave systems, either for ... more Filters are the basic component of transmitter and receiver in the microwave systems, either for band select or band reject units. Meanwhile, switchable microwave filters are highly impacting on the modern technologies, especially for cognitive radio applications. In this paper, a comparison of four different types of resonators in electronically switchable high Q bandstop to bandpass filters is reported, which are parallel-coupled, dual-mode ring, stepped-impedance dual mode and T-shape. These filters are designed based on lossy resonators, where it can be used to partially compensate for the RF losses. These switchable filters provide two modes of operation: bandstop and bandpass responses. In this comparison, all the filters are operated at 2.4 GHz frequency. The return loss and insertion loss for the bandstop filter is below 15 dB, while for bandpass filter, it is depending on the type of the resonators.
Jurnal Teknologi, 2016
This paper presented the design for dipole antenna at 2.4GHz for wireless local area network (WLA... more This paper presented the design for dipole antenna at 2.4GHz for wireless local area network (WLAN) application. This design aimed to improve the antenna gains and directivity. The printed dipole with reflector and director was designed and simulated using CST Microwave Studio. In this design, a metallic reflector was added in order to increase the gain. The director was added to the structure to maximize the antenna directivity. The simulation results showed that the antenna achieved a maximum gain of 5dB for the modified design and 6dBi for the directivity. Other antenna parameters were also investigated such as bandwidth, radiation pattern, and return los.
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Papers by Badrul Hisham Ahmad