SOME INVESTIGATIONS ON CAVITY BACKED SLOT AND PATCH ANTENNAS WITH A WAVEGUIDE BROAD WALL FEED

Abstract

In this dissertation, two different classes of cavity-backed antennas, namely, _ the cavity-backed patch antenna and cavity-backed slot array, have been investigated experimentally. The cavity has been coupled through a thick longitudinal slot in the broad wall of an X-band waveguide. The measured results of VSWR, input impedance, radiation pattern and gain are presented and discussed. - It is shown that a considerable miniaturization can be achieved with quite higher gain (14 dB) in the case of cavity-backed slot array-. The- gain of cavity-backed planar MPA is found to be 5 dB. The measured radiation pattern of both the cavity-backed planar antennas, are found to be quite directive. Based on generalised network formulation and method of moments technique, a general formulation is presented for a single element cavity-backed MPA. The related problem of Electromagnetic :coupling between waveguide and cavity has been analysed in detail. A computer program has been written in FORTRAN 77 to implement this technique.