Analytical calculation of input impedance of rectangular microstrip patch antennas on finite ground planes

A heuristic, analytically-based algorithm is proposed in this paper that calculates the input impedance for the canonical model of a probe-fed, rectangular microstrip patch antenna on a finite, rectangular ground plane. The cavity-model formula for the input impedance of a probe-fed microstrip antenna on an infinite ground plane is modified by incorporating the substrate and ground plane truncation in terms of the corresponding surface wave quality factor, Q(SW)(finite). Initial results from this heuristic technique, when compared compared against the rigorous (full-wave) numerical techniques in the IE3D or FIDELITY softwares, exhibit similar trends but different numerical values in impedance variations. These results further suggest that a. fast algorithm is feasible for design of wideband microstrip patches on finite ground planes, which can be further optimized via CAD tools for realizing wideband characteristics on finite ground planes.