Numerical and experimental investigation of cavity-backed arbitrary slot antennas

Abstract

The equivalence principle and the generalized network formulation are used to model the tangential electric field on arbitrary apertures, backed by a rectangular wave guide or cavity, in terms of equivalent magnetic currents. The coupling is through the aperture whose characteristics are expressed by the aperture admittance matrices of the cavity and half-space regions. The aperture coupling is then expressed as the sum of the two independent aperture admittances, with source terms related to the incident field. The result is an integral equation for the unknown aperture current. This integral equation is then reduced to a matrix equation using the method of moments. The formulation is then used to, investigate the electrical characteristics, i.e., aperture field distribution, aperture admittance, and radiation patterns of low-gain antennas such as H, cross, end-loaded, and centre-loaded slots backed by a cavity. Experimental results are also provided to verify the numerical results.