A numerically efficient full-wave analysis of a tunable rectangular microstrip patch

A full-wave analysis for determining the resonant frequency and half-power bandwidth of a rectangular microstrip antenna with an air gap is presented. To make the study more general and valid for various antennas structures; during the theoretical formulation the metallic patch is assumed to be embedded in a multilayered media containing isotropic and/or uniaxial anisotropic dielectrics. The proposed method for determining the Green's function leads to a concise form of this, expressed in terms of a 4 x 4 matrix multiplication, which is easily implemented. Using Galerkin's method in solving the integral equation numerically, the complex resonant frequency of the microstrip antenna with an air gap is studied with sinusoidal functions as basis functions, which show fast numerical convergence. The numerical results for Galerkin's method and experiments are in good agreement. The air gap tuning effect on the resonant frequency and half-power bandwidth is investigated. Finally, numerical results for the effects of uniaxial anisotropy in the substrate on the operating frequency of the rectangular microstrip antenna with an air gap are also presented.