Analysis of a circular-loop antenna backed by a circular ground-plane of finite extent

Using the circuit-geometric approach offered by the method of moments, this presentation addresses the problem of a circular-loop antenna backed by a circularly-shaped ground plane (reflector) of finite extent. By modeling the ground plane as an equivalent wire-grid formed by a finite number of radial and circular thin-wires, the problem essentially reduces to that of predicting the antenna performance characteristics arising from the electromagnetic interactions of this arrangement of thin-wire conductors, when excited by a prescribed source. Computational results obtained for input and radiation field parameters, in terms of an “aspect ratio” (defined as ratio of ground plane radius to that of the circular-loop element) and for a resonant (1λ) antenna, are presented in graphical format. The results are shown to compare favorably with some published data, to suggest that both formulation and solution of the problem are valid.