M. I. Sabran

A Dual-Band Diamond-Shaped Antenna for RFID Application

A novel dual-band single-layer substrate and diamond-shaped antenna is presented. The proposed antenna operates in dual-band frequency at UHF band (from 902 to 920 MHz) and ISM band (from 2.4 to 2.5 GHz), which is suitable for RFID application. Antenna frequencies were controlled by the shape and size of the radiating element. The proposed prototype antenna also has acceptable performances in terms of gain, efficiency, and directional radiation pattern. The antennas gain and efficiency are 7.8 dBi and 87 %, respectively, at the lower frequency band, while the corresponding values are 9.4 dBi and 94 % at the higher band. When compared to the simulated results, the measurements show good agreement in terms of return loss and radiation pattern.

A single band dual-fed circular polarization microstrip antenna for RFID application

This paper presents new design for single band circular polarization (CP) antenna with dual feedings. This antenna is designed for RFID application at 2.45 GHz. In this antenna design, the left corner side of the square patch is truncated. Then, two perpendicular feeding is connected to the patch to achieve Circular Polarization antenna. By combining the two perpendicular feedings with the truncated square patch in a dielectric substrate layer, the microstrip antenna for single band frequency circular polarization (CP) can be achieved with - 12.1dB return loss for 2.45 GHz. The simulated and measured results show that the proposed antenna has good circularly polarized radiations and the 3 dB axial-ratio bandwidth is more than 7.2%. Details of the obtained dual-band CP performances are presented and discussed in this report.

Dual-Band, Switched-Beam, Reconfigurable Antenna for WLAN Applications

The development of WLAN technology requires antennas with additional capabilities using simple and low-cost mechanisms. This letter presents a low-cost microstrip antenna integrated with simple p-i-n diodes as RF switches. The proposed antenna is capable of steering the beam in a dual-band mode: -19°, -59°, and 61° within the 2.45-GHz band, and 6°, -14°, and 16° within the 5.8-GHz band, which meets the IEEE 802.11a, b/g requirements. The antenna consists of three different dual-band elements, connected using an H-shaped transmission line at the radiating side. The novelty of this structure lies in the ground plane design. The H-shaped transmission line is used to integrate three different ground-plane structures.

Directional UWB antenna with a parabolic ground structure and split ring resonator for a 5.8 GHz band notch

A simple and compact circular planar monopole ultra-wide band antenna with a 5.8 GHz band rejection and directional radiation pattern is proposed in this paper. The split ring resonator (SRR) technique has been utilized to produce band rejection at 5.8 GHz. Some results and analysis on several SRR placements are highlighted in this paper. The parabolic ground structure is used to produce a directional radiation pattern together with bandwidth enhancement. The proposed prototype antenna has acceptable performances in terms of gain, efficiency, and directional radiation pattern. Simulated and experimental results are discussed.

Wide band open ended air gap RLSA antenna at 5.8GHz frequency band

A prototype of Air Gap RLSA has been designed and simulated using hybrid air gap and FR4 dielectric material. The 28% wide bandwidth has been recorded through this approach. A 12.35dBi directive gain also recorded from the simulation. The 13.3 degree beamwidth of the radiation pattern is sufficient for high directional application. Since the proposed application was for Point to Point Link, this study concluded the Air Gap RLSA is a new candidate for this application.

Miniaturized proximity coupled antenna with slot ring as defected ground structure

A new miniaturize proximity coupled microstrip antenna with defected ground plane is presented in this paper. The proposed antenna operates in the 2.45 GHz ISM band, which is suitable for WLAN application. By introducing the circular ring slot as a defected ground plane, a reduction size of radiating element is obtained. This circular slot ring results in a 45% reduction in the area of the patch element, and improves the proposed antenna efficiency by 85%. The evolution of the proposed design has been discussed clearly in this paper. Both simulation and measurement results show comparable values in terms of reflection coefficient performance.

Realization of a compact branch line couple using semi-lumped element

A single band branch line coupler for butler matrix with semi-lumped element has been proposed in this paper. The coupler is designed to operate properly at 5.8 GHz operating frequency. The capacitors with the value of 33 pF and 4.7 pF are realized as suitable values for lumped element components. It is found that the lumped element implementation is capable to greatly influence the size compactness of the coupler. The equivalent circuit is designed and simulated by using Agilent Advance Design System (ADS) software. As a result, the length of the fabricated proposed coupler is reduced by approximately 50% compared to the conventional coupler when the capacitors are embedded together with the transmission line. Moreover, the design which is etched on 1.6 mm thickness of FR4 substrate leads to the cost effectiveness. Prototypes of the proposed coupler have been constructed and successfully tested. The simulated and measurement results show the potential of the proposed coupler in the applications of butler matrix such as multi-port power amplifier, wireless local loop and transmit combining network in cellular Digital Cellular System (DCS) 1800 base station.

Monopole Ellipse Antenna for Ultra-Wideband Applications

In this paper, an Ultra wideband (UWB) ellipse monopole antenna is presented. The proposed antenna consists of an ellipse patch fed by a coplanar waveguide (CPW) transmission line. The antenna provides coverage for the UWB spectrum, achieving reflection coefficients ≤−10 dB from 2.83 to 10.66 GHz, thereby yielding a 7.77 GHz impedance bandwidth. The impedance bandwidth is achieved through a variation of the minor axis of the ellipse patch. The antenna gain is slightly enhanced by a center cut at the top ground plane. Simulations show quasi omnidirectional radiation patterns for the proposed antenna at three resonance frequencies of 4.8, 6.7 and 9.35 GHz within the UWB spectrum.

Loop Antenna Design for Lateral H-Field Uniformity in Misaligned HF-RFID Links

The performance of High-Frequency Radio Frequency Identification (HF-RFID) links depends on the alignment of the magnetically coupled interrogator and transponder antenna pairs. In this paper, we propose a design method to achieve lateral uniformity in the H-field of circular interrogator loop antennas to reduce the effect of lateral antenna misalignment. This is achieved by parametrically adjusting the radii of antenna turns to minimize the range of H-field variation at a given read-out distance. This design approach results in an enhancement of the axial H-field, while achieving minimal variation in the lateral H-field profile.

Dual band circularly polarized diamond-shaped antenna with directional capabilities for RFID application

A simple and novel diamond-shaped structure capable of producing dual band antenna with circular polarized enhancement is presented. The proposed antenna operates at both UHF and ISM bands which is suitable for RFID application. A pair of slots is introduced at the blended edge within the radiating element with optimum width and length, which can excite circular polarized antenna for both frequencies. The proposed antennas gain is improved by using a fixed air gap between substrate and ground plane. It is observed that there is good measure of agreement between the simulation and measurement return loss result, when compared.