Waveguide Bandstop Filters Based on Microwave Photonic Crystals with Parameters Controlled by n–i–p–i–n Diodes

A feasible design of a system with an allowed band with near-unity frequency-independent transmission utilizing the reflective properties of photonic crystals with dielectric filling and resonant irises in a setup with a Y-circulator is demonstrated. The existence of impurity modes of oscillation damping in the allowed band of this photonic crystal with disturbed periodicity is confirmed. Bandstop filters with parameters controlled by n–i–p–i–n diodes are constructed based on photonic crystals with resonant irises. These filters have a rejection level of >43.0 dB in the stop band and losses below 0.8 dB outside of it.