T. Sabapathy

Reconfigurable Four-Parasitic-Elements Patch Antenna for High-Gain Beam Switching Application

A reconfigurable beamforming of a four-parasitic-elements patch antenna (FPPA) for WiMAX application is presented. The proposed FPPA is successfully capable to steer the radiation pattern in azimuth planes (0 ^°, 45 ^°, 135 ^°, 225 ^°, and 315 ^° angles) and in elevation plane (0 ^°, 13 ^°, 15 ^°, 10 ^°, and 12 ^°). This is realized in the unique form of four parasitic elements encircling the center main radiator. The activation of the parasitic required a shorting pin to the ground that indicates on state condition, and vice versa. It is discovered in CST simulation software that the specified location of the pins are really significant to ensure the parasitic performs either as a reflector or director. Moreover, each of the shorting pins is linked to the RF p-i-n diode BAR5002v switch. Also, the FPPA is fabricated on a 130-mm square Taconic substrate. The proposed antenna design has a maximum gain of 8.2 dBi at all desired angles with a half-power beamwidth of 58 ^°.

Pattern-Reconfigurable Microstrip Patch Antenna With Multidirectional Beam for WiMAX Application

A parasitic planar patch antenna capable of multi directional pattern reconfiguration is presented. The antenna structure consists of a driven element surrounded by four parasitic elements that act either as reflector(s) or director(s) depending on the switching arrangement. Beam reconfiguration is achieved by using four p-i-n diode switches where the effect of switching technique on the overall element performance is investigated numerically and experimentally. The proposed antenna achieves nine distinguished main beam angular positions. Moreover, the proposed antenna has achieved excellent realized gain levels at all configuration scenarios with a minimum value of 7 dBi. Simulation and measurement results show good agreement and promising applications of such antenna structure in enhanced WiMAX systems.

A novel 2.45 Ghz switchable beam textile antenna (SBTA) for outdoor wireless body area network (WBAN) applications

A novel switchable beam textile antenna (SBTA) for wireless body area network (WBAN) applications is proposed. The SBTA is centrally-fed by a coaxial probe and the power distributed over four circular radiating elements. Four RF switches are integrated through which the SBTA is able to generate beam steering in four directions: 0 - , 90 - , 180 - , and 270 - , with a maximum directivity of 6.8dBi at 0 - . Its small size (88mm £ 88mm) and ∞exibility enables the structure to be easily integrated into safety jackets, rain coats, etc., for tracking, and search and rescue communication purposes. The structure successfully integrates reconflgurability into a wearable textile antenna.

Electronically reconfigurable beam steering antenna using embedded RF PIN based parasitic arrays (ERPPA)

In this paper, an electronically reconflgurable beam steering antenna using embedded RF PIN switches based parasitic array (ERPPA) is proposed for modern wireless communication systems that operate at 5.8GHz frequency. In the proposed antenna, a single driven element is fed by a coaxial probe, while each of the two parasitic elements is integrated with an RF PIN switches that embedded inside the substrate. In the conventional reconflgurable antennas, the RF PIN switches are mounted on narrow slots created on the top or bottom layer of the radiator/parasitic elements, which could lead to the dimensional changes of the antenna and degrade the performance in terms of beam steering and return loss. However, this research proposes an exclusive solution where the RF PIN diodes at parasitic elements are embedded inside the substrate thus no additional slots have to be created to mount the SMCs on the antenna. In this regard, the proposed antenna is highly competent to eliminate the intermodulation efiect generated by the RF PIN diodes and the other passive elements associated with the PIN diodes. In this research, extensive investigations revealed that the parasitic element dimension and the selection of RF PIN switches signiflcantly in∞uence

A Ground-Plane-Truncated, Broadly Steerable Yagi–Uda Patch Array Antenna

A low-profile, broadly steerable, and reconfigurable array antenna with parasitic patches is proposed and investigated in this work. For patch-type antenna arrays, improvement of the beam-scanning range using parasitic patches is very limited. The typically achieved scanning range is between -30° and +30° from the broadside. Increasing the number of parasitic elements generally will only provide a mere 3 °-5 ° improvement in terms of the beam-scanning range. In this work, the scanning range is improved by approximately 57% via a novel approach combining the additional parasitic elements and ground plane reduction techniques. Numerical and experimental results have validated that the array is capable of producing five different beam patterns directed towards -50°, -30°, 0°, +30°, and +50° steerable at the xz-plane using an optimized switching method and careful switch location selection on the parasitic elements.

1.575 GHz Circular Polarization wearable antenna with three different substrate materials

This paper presents an analysis of a Left-Handed Circular Polarization (LHCP) wearable antenna with different textile material (substrates) for Global Positioning System (GPS) application. The proposed antennas have achieved circular polarization (CP) by truncating two opposite edged of the square patch for all designed antennas with three different substrates. The analysis is focusing on using felt, jeans and cotton as substrates while maintaining shieldit supper as a conductor. The performance comparison have been made on the simulated reflection coefficient (S11), axial ratio (AR), bandwidth and gain. The results show that jeans fabric attained a better reflection coefficient of -41.36 dB at 1.575 GHz as compared to the other materials. Besides, the jeans has achieved good AR bandwidth of 17 MHz, followed by felt with AR bandwidth of 16 MH and cotton with AR bandwidth of 13 MHz.

1.575 GHz dual-polarization textile antenna (DPTA) for GPS application

This paper presents a novel dual-polarization textile antenna (DPTA) for Global Positioning System (GPS) applications. In this design, four sector radiating elements are centrally-fed by a coaxial probe. A novel antenna structure is successfully achieved by integrating electronic components into a wearable textile antenna. Silver loaded epoxy adhesive is used in embedding four PIN diode switches on ShieldIt super textile of the proposed antenna. The activation of certain PIN diode switches configuration determines the polarization of DPTA. Dimension-wise this antenna is compact and small where it consists of 40mm radius. The proposed DPTA design successfully generated dual polarization omni-directional radiation pattern with maximum gain 1.81 dBi at angle of 0°/3600, 90°, 180° and 270°. Its small size, flexible and wearable features enables this DPTA to be easily integrated onto safety jacket and rain coat for tracking, search and rescue applications.

A fabrication of intelligent spiral reconfigurable beam forming antenna for 2.35-2.39 Ghz applications and path loss measurements

A reconflgurable beam forming antenna prototype using a spiral feed line is proposed in this paper. The presented antenna is integrated with PIN diode switches at a speciflc location of spiral feed line. It is discovered that the beam steering ability is greatly in∞uenced by the spiral arm feed network. Four PIN diode switches have been incorporated at four difierent arms of spiral feed line to realize a beam forming ability. The intelligence behaviour of this antenna is conferred when the switches are connected to programmable intelligent computer (PIC) microcontroller. Certain conflgurations of PIC allow the antennas radiation patterns to be adaptively changed within 0.01ms. Therefore, the proposed antenna is capable of electronically forming the beam up to four difierent angles of +176 - , +10 - , i1 - and i12 - . This antenna is small in size with 100mm by 100mm of substrate dimension. In this research, the site fleld antenna performance relying on the received signal strength (RSS) testing is tested intensively in Universiti Malaysia Perlis with varied distant points of line-of- sight (LOS) and non-line-of-sight (NLOS) propagation. With good simulation and measurement results, this antenna could be a promising candidate to be installed in applications such as a smart antenna system, cognitive radio, WiMAX and long term evolution (LTE).

Review of angle of arrival (AOA) estimations through received signal strength indication (RSSI) for wireless sensors network (WSN)

Awareness of the physical location of each node is required by the many wireless sensor network (WSN) applications. There are various tracking schemes available such as time-of-flight, time difference of arrival and angle of arrival. This review paper focuses and describes previous related work regarding of the angle of arrival (AOA) estimations in particular through received signal strength indication (RSSI). AOA estimation is useful in tracking the desired signal and also improving the signal reception for movable users. With the AOA detection, the beam pattern of the antenna system can be reconfigured either mechanically or electrically to improve the signal reception. The AOA estimation with RSSI offers less complexity since the phase information of the signal will not be used to calculate the angle as usually practiced in the traditional phased array antenna systems. Hence this review focuses on identifying the advantages and disadvantages in AOA estimation through RSSI. The potential future direction of this research will be proposed at the end of this review.

2.45 GHz beam-steering textile antenna for WBAN application

A beam-streering textile antenna for wireless body area network (WBAN) applications is proposed and investigated in this work. This proposed antenna is centrally-fed by a coaxial probe before currents are distributed to the four circular radiating elements. This novel structure successfully integrated the reconfigurable feature into a wearable textile antenna using electronic components. Four RF switches are integrated at an ideal location of each arm without any external circuit. With certain specific RF switch configurations, the proposed antenna generated beam steering angles at 0°, 90°, 180° and 270° with a maximum directivity of 6.8 dBi at 0°/360°. Its small size of 88 mm2 square, flexible and wearable features enables this antenna to be easily integrated onto safety jacket and rain coat for tracking, search and rescue based communication purposes.