Design,Fabrication and Performance Evaluation of Micro-Strip Patch Antennas for Wireless Applications using Aperture Coupled Feed

Abstract

ABSTRACT Wireless communications have been developed widely and rapidly in the modern world especially during the last two decades. The future development of the personal communication devices will aim to provide image, speech and data communications at any time, and anywhere around the world. This indicates that the future communication terminal antennas must meet the requirements of multi-band or wideband to sufficiently cover the possible operating bands. However, the difficulty of antenna design increases when the number of operating frequency bands increases. In addition, for miniaturizing the wireless communication system, the antenna must also be small enough to be placed inside the system. However, in order to transmit and receive more information large bandwidths are required, and bandwidth enhancement is currently a popular research area. In this work presented, Transmission line model is used to simulate rectangular Microstrip Patch Antenna using aperture coupled feed. The aim is to study the effect of antenna dimensions Length (L), Width (W) and substrate parameters relative Dielectric constant (εr). Low dielectric constant substrates are generally preferred for maximum radiation. The conducting patch can take any shape rectangular, circular and there are many other configurations but rectangular is preferred. The length of the antenna is nearly half wavelength in the dielectric; it is a very critical parameter, which governs the resonant frequency of the antenna. In view of design, selection of the patch width and length are the major parameter s along with the feed line depth. So in this thesis, an aperture coupled antenna resonating at 10GHz, providing 234 MHz bandwidth for WLAN application (X Band) is designed in CST MICROWAVE STUDIO 9. The parametric study of the designed antenna is studied and the physical parameters examined in this study include the substrates and their dielectric constants, stub length and ground plane coupling slot length. Also an aperture coupled antenna resonating at 5.8GHz, providing 309 MHz bandwidth for WLAN application is designed. Loading slots at the non-resonating sides of the patch of single band aperture coupled antenna making it dual band for WLAN covering the bands 5.15MHz to 5.25MHz and 5.75MHz to 5.85MHz. and its fabrication has been attempted in this thesis. The antenna parameters like operating frequency, input impedance, VSWR, Bandwidth, Return loss, directivity and gain are determined for each antenna configuration. The operating frequency, input impedance, VSWR, Bandwidth, Return loss, directivity and gain of the single band antenna designed are 10GHz, 77.98ohm, 1.05, 234MHz, - 26.50988, 7.35 dBi and 9.153 dB respectively. The operating frequency, input impedance, VSWR, Bandwidth, Return loss, directivity and gain of the single band antenna designed are 5.8GHz, 50ohm, 1.0325, 309MHz, - 34.827, 5.652 dBi and 5.756 dB respectively. The dual band antenna having two slots on the non-resonating sides of patch resonates at 5.2 GHz and 5.8 GHz and provides a wide bandwidth of 771.51MHz. The directivity of the antenna at 5.20GHz and 5.8 GHz are 5.226dBi and 5.308dBi, and gain is 5.304 dB and 5.754dB respectively. The fabrication of the dual band is also done as well as the testing is done using VNA model no: E5071C. The testing results along with the comparison between testing results and simulated results are also shown. The operating frequency of single band at 5.8GHz is obtained at 5.83GHz, also the range of frequencies covered by dual band has shifted to 4.740 GHz to 5.632GHz. The reason for shifting has also been explained.