A third‐order bandpass iris filter with reconfigurable dielectric irises

A novel concept of reconfiguring high Q‐factor iris filters, to operate in different frequency bands, is presented. Compared to traditional iris filters, the air‐filled irises are here replaced with dielectric substrate, similarly as the concept of substrate integrated waveguide. By controlling RF MEMS switches placed on the dielectric substrate, the equivalent iris width and thickness, and the resonant cavity length can be reconfigured simultaneously. As a demonstration of the concept, this article has proposed a third‐order bandpass filter consisting of 3 waveguide sections made of brass and 4 inverters fabricated on Rogers RT/duroid 5880 substrate. Constant absolute bandwidths between different states and theoretical unloaded Q‐factor of 1800 are achievable in our approach.