CAVITY-BACKED SLOT AND PATCH ANTENNAS FED BY A WAVEGUIDE END-WALL SLOT

Abstract

The network formulation for cavity-backed patch array fed by a waveguide end-wall slot using generalized network formulation based on the application of equivalence principle is presented. Moreover, the electromagnetic coupling between the rectangular waveguide and a lossy rectangular cavity through a thick narrow slot in the transverse cross-section of the waveguide is analyzed. This problem has been formulated in terms of a pair of coupled operator equations using equivalence principle with equivalent magnetic currents as the unknowns. Using the method of moments and with the help of a computer program, coupling coefficient and VSWR are computed for the problem. Results of experimental investigations, carried out on a number of cavity-backed antennas viz, a linear slot array with 3 slots in H plane, a 5 x 3 planar slot array, a single patch microstrip antenna and a 5x3 planar microstrip patch array are also presented. The results obtained show that cavity-backed antennas are highly frequency dependent and have narrow bandwidth. However, sufficient gain and narrow beamwidths were observed with cavity-backed microstrip and slot arrays.