Photonic band gap formation by microstrip ring: A way to reduce the size of microwave photonic band gap structures

Abstract

We show that a microstrip ring with a narrow gap exhibits a photonic band gap (PBG) that is generally believed to be created by a periodic array. The discontinuity of impedance at the narrow gap induces multiple reflections with fixed phase correlation necessary to make the PBG. We also discuss the PBG frequency tuning achieved by applying an external voltage on a varactor mounted on the gap and applications of this PBG ring as a tunable band stop filter and a microwave switch.