Equivalent Circuit Model of Coaxial Probes for Patch Antennas

An equivalent circuit model of coaxial probes is derived directly from the intrinsic via circuit model. As all the higher-order evanescent modes have been included analytically in the parasitic circuit elements, only the propagating mode needs to be considered by the simplest uniform-current model of a coaxial probe in numerical solvers such as finite element method (FEM) or finite difference time domain (FDTD). This avoid dense meshes or sub-gridding techniques and greatly reduces the computational efforts for accurate calculation of the probe input impedance. The derived equivalent circuit model and the new feeding technique have been validated by both analytical formulas and numerical simulations.