NUMERICAL AND EXPERIMENTAL INVESTIGATIONS ON A CAVITY BACKED RECTANGULAR MICROSTRIP PATCH ANTENNA

Abstract

Microstrip antennas are extremely good for use in various applications because of their several attractive features such as low cost, light weight, conformability and their compatibility with solid state devices etc. The serious disadvantage of the microstrip patch antennas is their narrow bandwidth, which results from the small separation between the patch and ground plane. The easiest way to increase the bandwidth is to use a thicker substrate. Thick substrates, however, cause the propagation of surface waves, which reduces the radiation efficiency and increases the coupling between the array elements. To avoid these undesirable effects, a metallic cavity is used to enclose the patch to suppress the effect of surface waves. Metallic cavity can also serve as a heat sink to improve the heat dissipation. In the present work, Experimental investigations were carried out on the cavity backed rectangular patch antenna fed by infinite microstrip line and open-ended microstrip line. Antenna has been investigated by increasing the depth of cavity in steps. Various experimental results have been presented here on Input impedance, VSWR. Bandwidth, Gain and Radiation patterns of the antenna operating at 3 GHz. For the numerical analysis of the cavity backed microstrip patch antenna, the moment matrix formation and various matrix element expressions have been presented here. By using these expressions, program has been written in C++ and numerical results are presented.