Modified Metallic Photonic Crystal Structure for Planar Microwave Devices

In this paper, a modified double-layered metallic photonic crystal (MPhC) structure is proposed for designing microwave planar devices. The modified MPhC is implemented by inserting a thin air layer into a traditional planar MPhC consisting of a periodic metallic post-array sandwiched by a parallel plate waveguide. As examples, a point-defect resonator based on the modified MPhC is implemented by eliminating one or several metallic posts. It can be found that the resonant frequencies of the novel cavities can be tuned by changing the thickness of the air-gap. To validate the proposed structure, an air-gap inserted point-defect-cavity is investigated. Moreover, a BPF (bandpass filter) is designed using the proposed MPhC cavities.