Ahmad Rashidy Razali

Universiti Teknologi MARA | UiTM · Faculty of Electrical Engineering

The importance of identification tags, or military pendants, cannot be overstated in military and defence applications. However, the current system presents several limitations, including potential human error and the need for physical contact to access information. Additionally, existing military pendants have limited storage capacity for critical...

Size and flexibility are the two main elements that must be considered in designing a near-field communication (NFC) tag antenna because they will determine the performance of the whole system. The previously designed NFC tag antenna, which is made of a rigid substrate such as FR-4, limited the application of the tag to only on a flat surface. The...

p>In this research the dielectric constant of three types of Malaysian honey has been investigated using a non-destructive measurement technique. The objective of this research is to assess the dielectric constant of the three types of honey in Malaysia using a non-destructive measurement technique known as an open-ended coaxial probe in the freque...

A compact meandered dual-bands monopole antenna for the application of a wireless local area network (WLAN) is proposed. This antenna has two operating frequency bands which are 2.4 GHz and 5.2 GHz and denoted as lower and upper operating bands respectively. In the antenna design, a meandered arms structure has been proposed to obtain a compact siz...

This paper presents a multiband patch antenna for LTE application. Conventional single band antenna only operates at one specific frequency and will require multiple single band antenna to support multiband application. Consequently, the antennas will consume more space in the microwave circuitry. The propose antenna is designed to operate at multi...

The Development of a wearable sensor that can monitor a heart rate and body temperature based on ESP8266 NodeMCU microcontroller is proposed in this project. To realize the system, two biomedical sensors are used which are MAX30205 and SEN11574 Pulse Rate Sensor. The sensors should be wearable to make it easy to be used by the patient. All the data...

Microwave absorber able to inhibit the reflection of electromagnetic radiation. Microwave absorbers are used in an anechoic chamber along with its wall, ceiling and floor for the electromagnetic compatibility (EMC) and electromagnetic interference (EMI) evaluation. This research is to develop a flat shape of biomass absorbers using an agricultural...

The objective of this study is to investigate the potential material, PDMS as a flexible antenna substrate for body centric wireless application. A stretchable and flexible antenna design fabricated with thin copper as the radiating element and using the polydimethylsiloxane as the substrate is presented. Thin copper sheet based conductor has been...

This paper investigates the performance of multilayer pyramidal hollow green biomass coated absorbing materials. The designed absorber is simulated using CST Microwave Studio. Several experimental evaluations have been executed to investigate the performance of the tested absorber using free space arch measurement method. The frequency between 8 an...

This paper presents an investigation of an inset-fed microstrip patch antenna designed with silver nanowires (AgNWs) radiating patch and polydimethylsiloxane (PDMS) substrate. Highly conductive and stretchable radiating element AgNWs is embedded in flexible and durable PDMS elastomer. The antenna is designed to be wearable and flexible for body-cen...

The paper discusses the fabrication of fat tissue using glyoxal and glutaraldehyde as a cross linking agent to be used in breast phantom for microwave imaging application. The fabricated fat tissue’s dielectric constant is measured in the ultra-wideband frequency range of 3.1–10.6 GHz. In brief this paper addresses the two issues of breast phantom...

A miniaturized Planar Inverted Antenna F-Antenna for LTE700M service band is presented. The main radiator of PIFA antenna is been folded into three radiating arm which provide optimized dimensions. Then, stair-shaped geometry have been used in order enhance impedance bandwidth for both lower band and higher band. Finally, the size of the finite gro...

An approach to design a compact monopole antenna for use in portable RF transceivers that feature wideband performance and miniaturized dimension is presented. The antenna structure is initially designed as a microstrip-fed planar monopole quarter elliptical shape supported by a 60 × 90 mm2 ground plane bolstered on FR-4 substrate. A parasitic micr...

Radiation Absorbing Material (RAM) is used to absorb radiations of electromagnetic wave surrounding us. Thus, the multiple layers’ microwave absorber using biomass composite materials could be one of the solutions to address the problem. In order to effectively absorb the radiation of electromagnetic wave, the multiple layers’ absorber is character...

An investigation into the effect of ground slot in a microstrip antenna is presented. Initially, a planar inverted-F antenna dedicated for 2.45 GHz WLAN lower band is designed. Its rectangular ground plane is then introduced with slots to excite new magnetic resonance for 5.2/5.8 GHz WLAN upper band. The slots are optimized by tuning their three di...

This paper presents the performance effect of hollow pyramidal microwave absorber that had been applied with slotted array principle. The Sierpinski triangle was used as the slotted on the hollow pyramidal microwave absorber. This paper includes the theories, simulation and measurement result. The simulation using CST Microwave Studio Suite used to...

Two planar antennas for compact multiband transceivers are presented, that employ an open-ended microstrip feedline that couples to multiple open-ended ground slots. The effect of separately introducing each of the slots on the antenna performance is outlined, and it is shown that the resonant frequencies of the antennas can be independently contro...

In this paper, a planar inverted-F antenna with the bandwidth enhancement techniques is presented. The antenna is designed and proposed a new modification of its shorting arm and introduction of ground slots to enhance the bandwidth of the fundamental resonant originally at 2.3 GHz. With this proposed configuration the original bandwidth of 500 MHz...

This paper presents an ultra-wideband Coplanar Inverted-F Antenna (CIFA) proposed for WiMAX and WLAN band applications. This paper also introduces an ultra-wideband CIFA based on two techniques which are bandwidth enhancement and radiator miniaturization. As a result, this modification increases the antenna resonant bandwidth to cover almost all UW...

A compact, planar antenna is proposed, which uses negative-refractive-index transmission-line (NRI-TL) metamaterial loading in order to achieve multiband operation with orthogonal pattern diversity in different bands. The antenna occupies a small footprint, which is a key requirement for its future use in a heart failure monitoring system. It is sh...

Antennas for wireless communications are commonly developed in the form of passive planar structures, which consist of a main radiating element, a supporting ground plane, a supporting substrate, and a feeding structure. The design configurations, sizes and type of substrates will depend on the desired frequency of operation and its radiation perfo...

In this article, the design of a dual‐band slim inverted‐F antenna with an enhanced operational bandwidth is presented. Initially, a slim inverted‐F antenna for operation in 850 and 1900 MHz bands supported by a large ground plane of 120 × 40 mm is introduced. This antenna offers dual band operation but with narrow bandwidth around each desired fre...

In this letter, the design of a super slim multiband wrapped inverted-F antenna that covers the frequency bands allocated for GSM, DCS, and PCS wireless services is described. In the first step, the quarter-wavelength (at 850 MHz) open-end arm of an inverted-F radiator is folded and meandered. Then, the antenna is wrapped using a fourth-order foldi...

This paper presents the design of a super slim multiband wrapped inverted-F antenna that covers the frequency bands allocated for GSM, DCS and PCS wireless services. In the first step, the quarter-wavelength size (at 850 MHz) open-end arm of an inverted-F radiator is folded and meandered. Then the antenna is wrapped using a fourth-order folding tec...

This paper presents an investigation into a coplanar inverted-F antenna with a ground slot whose electrical size is varied by turning ON and OFF PIN diode switches. Initially, a quarter wavelength coplanar inverted-F radiator is designed to operate at 900MHz. To minimize its size, the radiator is folded to occupy an area of approximately 10 × 40mm2...

The paper presents the design of a compact penta-band antenna for portable and embedded devices. The bands covered include GSM-900/1800/1900, UMTS-2100 and 2.4 GHz WLAN. A folded planar inverted-F antenna with a relocated shorting-stub and a secondary arm introduced on the bottom layer of the substrate provides resonances at the 900, 1800 and 2400...

In this article, a coplanar inverted-F antenna with an electronically controlled ground slot enabling recon-gurability is proposed. Initially a quarter wavelength coplanar inverted-F radiator is designed to operate at 900 MHz. To minimize its size, the radiator is folded to occupy an area of about 10 × 40mm 2. Next, a ground slot is introduced to e...

This paper describes various miniaturization techniques of multiband antennas for portable transceivers. The considered techniques include folding, meandering and wrapping of the primary radiator. In addition, utilization of ground slots to widen the existing or generate new bands is described. These techniques are illustrated through design exampl...

In this paper, a novel folded quarter-elliptical wideband monopole antenna for portable wireless applications has been presented. The proposed antenna has been fabricated and experimentally offers a wideband performance from 850MHz to 6GHz at 6dB return loss or VSWR 3:1. At this reference RL/VSWR level, the proposed antenna covers most of popular p...

This article describes two designs of a Coplanar Inverted F Antenna (CIFA) which employ a microstripline as a feeding element and open-end ground slots to obtain a multiband operation in the frequency band of 2.4 and 6 GHz.Investigations are performed with regard to two different orientations of ground slots one being parallel and the other perpend...

This paper presents investigations into a compact antenna for use in portable devices to access almost all modern wireless services from about 800MHz to 6GHz. Initially, a microstrip-fed planar monopole of quarter-elliptical shape on FR-4 substrate is designed to generate a wide impedance bandwidth. This radiating element is augmented with a parasi...

This letter describes the design of a compact monopole antenna for use in a portable transceiver to access almost all modern wireless services from 850 MHz to 6 GHz. Initially, a microstrip-fed planar monopole of quarter-elliptical shape accompanied by a ground plane of 60 × 90 mm² on FR-4 substrate is designed. To generate an ultrawide...

In this paper, a new excitation technique for a printed planar inverted F antenna (PIFA) is described to obtain multi-band operation. In the proposed technique, the printed PIFA is fed from a microstrip line which is coupled to open-end slots in a finite ground. A strong coupling between the microstripline and the ground slots is responsible for ge...

The design of a novel dual-band PIFA of compact size for WLAN application has been presented. This new miniaturized PIFA is capable to operate in dual-band that cover 2.4-2.4835 GHz band for 802.11/b/g and 5.15-5.825 GHz band for 802.11a (indoor and outdoor) for application. The operation in the upper band is achieved by the introduction of a groun...

This letter reports on a new idea to achieve multiband operation of a coplanar inverted-F antenna (CIFA). In the proposed approach, a microstripline is used to feed the primary CIFA radiator. This feeding arrangement allows for a flexible coupling of the feed to open-end slots in the finite-size ground to launch new resonant frequencies. Two config...

In the last decade, compact low-profile antennas featuring multiband operation have drawn a considerable interest from designers of portable wireless devices. The demand for these antennas stems from the fact that modern portable devices have to access an increased number of wireless services across the frequency spectrum from approximately 880MHz...