Band-Switchable Substrate-Integrated Waveguide Resonator and Filter

In this paper, we present a new band-switchable substrate-integrated waveguide (SIW) filter structure and its design method. The filter can have a passband either in S- or X-band, or have two passbands-one in S-band and the other one in X-band-at the same time. The presented design method allows us to obtain the bandwidths of two passbands independently. To verify the presented filter structure and design method, we have designed, fabricated, and measured three bandpass filters having three different pairs of bandwidths using frequency-tunable SIW resonators. By virtue of the frequency-tunable resonators, the filter can be continuously tuned in both frequency bands.