On highly directive EBG-based antennas

This paper compares two schemes that use Electromagnetic Band Gap (EBG) structures to enhance the directivity of omnidirectional radiators. The structures consist of identical dielectric cylinders, arranged in two-dimensional periodic patterns, which are designed to work either inside the first bandgap or at its upper edge. In the former case the EBG material acts as a partially reflecting mirror and, combined with a ground plane, realizes a cavity, where the source is placed. In the latter method, the source is embedded inside the EBG, that supports a lattice mode. Several structures are optimized and their performances are compared mostly in terms of radiation parameters to highlight strengths and weaknesses of the two approaches.