Focusing characteristics of a metallic cylindrical electromagnetic band gap structure with defects

The focusing characteristics of 2D-Cylindrical Electromagnetic Band Gap (CEBG) structures constituted of metallic wires and with defects are analyzed numerically for directive antennas application. The introduction of defects into the periodic structures consists of removing one or multiple wires. The simulations were carried out with a Finite Difference Time Domain (FDTD) code, where the excitation is a line source and the CEBG structure is considered infinite in the vertical direction. Numerical results showing the effects of the number of cylindrical layers and of the number of defects are presented and discussed. These results allow to determine the structures giving best focusing performance and to obtain the frequency band for directive radiation.