An efficient numerical model for analysis of microstrip antenna

An efficient model for analysis of electromagnetic (EM) radiation from microstrip patch antennas is presented in this paper. In this model, the higher order hierarchical legendre (HOHL) basis functions rather than conventional RWG basis functions are used to describe the current on metal surface, because HOHL basis functions have the ability to describe the significant fringe current which parallel to the antenna patch edge correctly with less unknowns. The volume-surface integral equation (VSIE) is particularly convenient for modeling the microstrip patch antenna with a thin finite dielectric substrate. However, a significant shifting of the solved resonant frequency always occurs due to the failure of conventional VSIE to describe the boundary condition of the interface between metal and dielectric. Moreover, the unknown number of conventional VSIE is very large and the convergence of iteration solutions is very slow. The quasi-static relation of the current on the parallel plate capacitor is built in this model as the added field continuity boundary condition at the dielectric-conductor interface, in order to solve the frequency shift problem of traditional VSIE model. Finally, based on the basic idea of the thin dielectric sheet (TDS) approach for dielectric-coated PEC surfaces, no more volume unknowns is required in this new model and the number of total unknowns is reduced significantly. Numerical examples shows that this model is able to remove the frequency shit problem, reduce the number of unknowns and speed up the iteration convergence significantly compared to conventional VSIE model.