Microstrip antennas with an airgap

The authors investigate the complex resonant frequencies of a circular microstrip patch mounted on a spherical body using the spectral domain method. In this method, the effects of the dielectric substrate and of the metallic sphere are incorporated by the rigorous Green´s function formulation. Vector Legendre series is defined to simplify the process of formulation. Galerkin´s procedure is employed to solve for the complex resonant frequencies. The cavity model surface current functions are used as the basis functions. The resonant frequencies and Q-factors of the TM₁₁ mode are presented