ABSTRACT
Electromagnetic band gaps (EBG) are periodic structures that are able to inhibit signal propagation at certain frequencies and directions. This chapter aims to highlight some potential applications of EBGs in planar circuit technology. Planar EBGs are essentially transmission lines with periodic perturbations in wave impedance. The chapter presents examples of applications of EBGs to the suppression of undesired harmonics in microwave filters. It focuses on the application of capacitively loaded transmission lines to reduce the size and improve the performance of planar microwave components. PBG structures were first applied to the optical domain, but later, periodic structures were used at microwave frequencies as reflectors in microstrip technology. One of the most interesting applications of EBG-based transmission lines acting as Bragg reflectors is the suppression of undesired harmonics in planar microwave filters. Periodic EBG structures can be implemented by loading a transmission line with shunt-connected capacitances.
