Magnetically tunable substrate integrated waveguide bandpass filters employing ferrites

A novel tuning solution for planar reconfigurable microwave filters is presented. The proposed filters are implemented using substrate integrated waveguide (SIW) technology featuring compact size, low cost, high Q, and high power-capacity. Tunablity of the proposed reconfigurable filters is achieved by adjusting dc-magnetic bias applied to the ferrite material. Compared to the previously reported reconfigurable filters based on electrical adjustment enabled by mechanical modifications, the proposed filters offer a relatively wide tuning range and stable tenability, while dramatically reducing the complexity of external control system. Effects of filters parameters´ including the ferrite material, magnetic DC bias, and SIW configuration, on reconfigurable performance are discussed. Simulation examples of single-circulator and double-circulators tunable bandpass filters are realized using EM simulations for demonstrating the underlying principle.