Accurate analysis and synthesis of annular ring microstrip antennas

A fast accurate analytical model is developed for the analysis and synthesis of annular-ring multilayer printed antennas. It uses a variational definition of the surface charge density to take into account the shape of the radiating element. The input impedance is determined from an equivalent electrical circuit. A computer algebra system is used for the theoretical polynomial expression of the zeros of the characteristic equation. Numerical results are given and compared with experiments and rigorous models. A high level of agreement is observed. The very short computing time allows inclusion in a microstrip antenna computer aided design system