Mohd Tarmizi Ali

A NOVEL OF RECONFIGURABLE PLANAR ANTENNA ARRAY (RPAA) WITH BEAM STEERING CONTROL

A new antenna structure is formed by combining the concept of reconfigurable planar antenna array (RPAA) with the parasitic elements to produce beam steering patterns. The antenna has been integrated with the PIN diode switches that enable the beam to be steered in the desired direction. This has been done by changing the switch state to either on or off mode. In this work, a number of parasitic elements have been applied to the antenna, namely reflectors and directors. They are placed in between the driven elements, which is aimed to improve the beam steering angle. With such configuration, the main beam radiated by the array can be tilted due to the effect of mutual coupling between the driven elements and parasitic elements (reflectors and director). The unique property of this antenna design is that instead of fabricating all together in the same plane, the antennas feeding network is separated from the antenna radiating elements (the patches) by an air gap distance. This allows reducing the spurious effects from the feeding line. The optimization results for the resonant frequencies of the antennas with variable air gap heights are also been studied. The antenna is made for 5.8 GHz. Good agreement is achieved between the simulation and measurement.

DESIGN OF RECONFIGURABLE MULTIPLE ELEMENTS MICROSTRIP RECTANGULAR LINEAR ARRAY ANTENNA

This paper presents a reconfigurable multiple element microstrip rectangular linear array antenna integrated with radio frequency (RF) switches. The corporate feed design concept is used to excite the linear array antenna that consists of 8 elements of rectangular patches at 5.8 GHz. Two PIN diode switches were deployed at the feeding line to activate the two arrays of patches that are located on the left and right sides of the antenna structure. The behavior of the reconfigurable multiple element linear antenna array system has been investigated with respect to the beam shaping characteristic. The comparisons of the performance between two structures, with and without Wilkinson Power Divider (WPD) are discussed in this paper. Two different beam patterns were achieved through the reconfigurable antenna at different number of elements design that incorporates with PIN diode switches and modified WPD concept. The simulation and the measurement results for 4 and 8 elements array antenna structure are presented.

E-shape microstrip patch antenna for wideband applications

This paper presents the design of E-shaped microstrip single patch antenna with wideband operating frequency for wireless application. The antenna design is an improvement from previous research and it is simulated using CST Microwave Studio 2009 software. Parametric study was included to determine affect of design towards the antenna performance. The performance of the designed antenna was analyzed in term of bandwidth, gain, return loss, VSWR, and radiation pattern. The design was optimized to meet the best possible result. Substrate used was C-Foam PF-2 which has a similar dielectric constant of air. The results show the wideband antenna is able to operate from 8.34 GHz to 13.86 GHz frequency band with optimum frequency at 8.73 GHz.

Gain enhancement of air substrates at 5.8GHz for microstrip antenna array

This paper concerned on enhancement of gain for microstrip patch planar array antenna. The structure in this project is 2 by 2 microstrip patch planar array antenna using air substrate with εr= 1at frequency 5.8 GHz. Frequency for 5.8GHz can be applied to unlicensed WiMAX. In this project, the simulation is performed by using the simulation software Computer Simulation Technology (CST) Microwave Studiowhich is a commercially available electromagnetic simulator based on finite difference time domain technique. The novelty of the design is the application of air to replace regular Flame Retardant 4 (FR-4) materials as the substrate.The substrate used for the design is C-foam (thickness = 3mm) which represent as air gap. Copper foil with thickness 0.12mm is used as the patch. The performance of the designed antenna was analyzed in term of bandwidth, gain, return loss, VSWR, and radiation pattern.

Aperture-Coupled Frequency and Patterns Reconfigurable Microstrip Stacked Array Antenna

This paper investigates a novel structure of a reconfigurable microstrip antenna integrated with the aperture coupling technique which can reduce spurious radiation pattern with stacked patch in order to enhance the gain and bandwidth performance. The antenna design implements a new concept of the frequency reconfigurability methods applying in an aperture-coupled technique. Four PIN diode switches named as Switch A were used to activate the selected aperture slots on the ground, thus resulting in two different operating frequencies either at 2.6 or 3.5 GHz. Meanwhile, an additional four PIN diode switches named Switch B, positioned at the four L-stub elements were used to turn ON the patterns capabilities while maintaining the frequencies. The beam angle of the antenna can be controlled with turning ON Switch C and Switch D alternately in order to activate selected numbers of stacked radiating patches, either the two upper patches or two lower patches. With six cases of the switches configuration, the antenna has the capability to change its patterns with its beam directed at +32°, +3°, or -1° at 2.6 GHz or at +28°, +23°, or -24° at 3.5 GHz.

Reconfigurable linear array antenna with beam shaping at 5.8GHz

In this paper, experimental data was demonstrated the concepts of reconfigurable number of elements that produced broad beam and narrow beam radiating pattern characteristic. Using modified WPD in the antenna structure, produced better performance in term of return loss characteristic. This research has taken advantage of the flexibility of the number of element technique by applying it to the problem of reconfigurable multiple beam array combination. The reconfigurable dual-beam antenna pattern at fixed frequencies across the entire 5.7-5.9 GHz band was presented in this paper with excellent radiation patterns.

A Reconfigurable Monopole Antenna With Fluorescent Tubes Using Plasma Windowing Concepts for 4.9-GHz Application

This paper aimed at investigating the performance of plasma windowing concept in terms of radiation pattern, gain, and S-parameter. The antenna structure consists of 12 tubes of commercial fluorescent lamps that contain a mixture of mercury vapor and argon gas, which upon electrification, forms plasma. After getting sufficient voltage, the gas inside the fluorescent tube will ionize to plasma and form a plasma column. When all of the tubes surrounding the antenna are electrified, the radiation is trapped inside. By leaving one or more of the tubes in a nonelectrified state, apertures are formed in the plasma shield, which allow radiation to escape. The plasma frequency in this experiment is equal to 5.634e11 Hz. This antenna design is at 4.9 GHz. The designing of plasma antenna using fluorescent tubes has created advancement in antenna industry especially in reconfigurable antenna field.

A compact dipole UHF-RFID tag antenna

This paper presents a novel design of a compact dipole UHF-RFID tag antenna for the Malaysia frequency band (919-921 MHz). The design of the proposed tag antenna included meandering technique and capacitive-tip loading structure to reduce the size of the tag antenna. The overall dimension of the antenna is 43 × 26 × 0.787 mm3. The tag is composed of copper layer traces, SOT1122 chip from NXP Semiconductor and Rogers 5880 substrate with the relative permittivity of 2.2. The performance of the proposed tag antenna was analyzed in terms of matched impedance, return loss, antenna gain and tag reading range through CST simulation software. The tag reading range was also experimentally measured and the result was compared with the simulation result. The tag antenna has a long read range of 9.6 m in a direction normal to the reader.

Design of wideband microstrip patch antenna using L-probe fed at 2.6 GHz

This paper proposes the design of wideband microstrip patch antenna using L-probe fed. The structure consist of air-filled substrate with dielectric permittivity, ε0 and thickness, h0 which is sandwiched between superstrate and a ground plane. The design is constructed with respect to 2.6 GHz of centre frequency. Parametric study were performed to analyze the effects of the design towards antennas performance. An accomplishment of the design has been carried out using CST Microwave Studio software. Simulation has been performed and results clearly showed the capability and potential of the antenna design itself. The utilization of Lprobe fed as well as parasitic elements provide bandwidth enhancement, while the use of parallel slots offers patch size reduction and gain enhancement. To conclude, antennas performance was analyzed in terms of bandwidth, gain, VSWR and radiation pattern. The simulated impedance bandwidth of 11.04% ranging from 2.444 Ghz to 2.729 Ghz is achieved at 10 dB return loss with VSWR<;2.

Preliminary studies on the use of natural rubber in the design of flexible microstrip antennas

In this paper, we report the first attempt to use natural rubber as a substrate in the design of flexible microstrip patch antennas. The effects of dielectric properties of rubber on the performance of microstrip patch antennas are presented. The patch geometry has been designed and optimized at a frequency of 10 GHz. It has been found that for a fixed substrate thickness, the antenna directivity and return loss decrease with increasing relative permittivity. However for a given permittivity, increasing the substrate thickness will result in lower return loss but higher directivity. Hence, some trade-off must be made between these parameters in order to obtain an optimum design.