Application of the Coupled Mode Theory to the Analysis and Design of PBG Structures in Microstrip Technology

In this paper the coupled mode theory is formulated to analyze PBG structures in microstrip technology obtaining a simplified system of coupled mode equations. Several reasonable approximations are introduced giving rise to analytical solutions for the problem. The analytical solutions allow the characterization of the infinite ideal structure and of the actual finite size device. The obtained results, both numerical and analytical, are checked against measurements showing very good agreement. The proposed method is very attractive for the study of these devices since it avoids the time-consuming full-wave electromagnetic simulations customarily employed and provides analytical solutions that are very useful for analysis and synthesis purposes.