Evaluation of Input Impedance and Radar Cross Section of Probe-Fed Microstrip Patch Elements Using an Accurate Feed Model

Input impedance and radar cross section (RCS) results for probe-fed single rectangular and circular microstrip patch elements obtained using an accurate and efficient numerical model are presented. The model uses a full-wave Green’s function/Galerkin solution in which the connection of a vertical probe feed to the patch is rigorously included in the analysis by use of a special basis function called the “attachment mode,” which is derived from the corresponding cavity model solution. Comparisons with measured input impedance and monostatic radar cross section data demonstrate the efficacy of the theory. This model accurately predicts the performance of probe-fed patches printed on thick and/or high dielectric constant substrates and patch elements with more than one probe feed, cases where other less rigorous models fail.