Single-Filter Structure With Tunable Operating Frequency in Noncontiguous Bands

In this paper, we present a frequency-tunable substrate-integrated waveguide bandpass filter of which the operating frequency band can be switched between S-band and X-band. One of unique features of the presented filter is that a single-filter structure can replace a filter bank composed of an S-band filter, an X-band filter, and two switches at input and output ports for selecting one of two filters. In addition, the filter can tune the center frequency in each band. This paper provides the design method, fabrication, and measurement of the presented filter structure.