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^finite_sw. Initial results from this heuristic technique, when 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.