Analysis of cavity antennas with chiral substrates and superstrates through the Finite Element Method

Recently, advances in material technology permit the realization of chiral materials for employment in multilayer substrate/superstrate configurations with dimensions that are even a small fraction of the wavelength. This capability makes possible the fabrication of integrated circuits and planar antennas with chiral loading materials that are very promising for telecommunication purposes. The recent extension of the finite element variational formulation given by the authors for the analysis of cavity-backed patch antennas with complex loading materials facilitated the study of microwave components with chiral dielectrics and is exploited in this paper to investigate some electrical features of patches with chiral substrates and superstrates. The main result obtained is the reduction of the resonant frequency with an increase in the chirality admittance of the material. This permits the realization of very compact antennas compared with antennas fabricated using solely isotropic materials. An example showing the dimension reduction obtained through the employment of chiral materials is also presented. Finally, the effect of a chiral superstrate on a conventional patch and the mutual coupling between two patches when chiral substrates are used is also presented.