In this paper, new expressions for the effective radius and fringing capacitance have been derived to predict accurately the resonant frequency of the two-layered circular microstrip patch antenna. These expressions are obtained based on genetic algorithm and the data base is generated using moment method (MOM). The proposed model is very simple, fast, and valid for an entire range of permittivities and thicknesses of two-layered substrate. The present model has been validated by comparing our numerical results obtained for the resonant frequencies with measurements. Finaly, the effect of the two-layered substrate on the resonant charateristics of the circular microstrip patch antenna has been presented.

This paper, present the resonant and the radiation characteristics of superconducting rectangular microstrip antenna printed on uniaxailly anisotropic substrate using an electromagnetic approach based on cavity model in conjunction with electromagnetic knowledge. The cavity model combined with London's equations and the Gorter-Casimir two-fluid model has been improved to investigate the resonant characteristics as well as the radiation patterns of high Tc superconducting rectangular microstrip patch in the case where the patch is printed on uniaxially anisotropic substrate materials. The most advantage of our extended model include low computational cost and mathematical simplify. The numerical simulation of this modeling shows excellent agreement with experimental results available in the literature. Finally, radiation patterns of superconducting rectangular patch on anisotropic substrate are also presented.