LAUSR

A compact dual-band bandpass filter with controllable center frequencies based on the 90° fan-shaped substrate integrated waveguide resonator (FSSIWR) is first proposed in this letter. Dual-band response is achieved by the fundamental mode (TM101 mode) and high mode (TM201 mode) of the FSSIWR, respectively. In this design, two pairs of the posts are loaded at the 45° direction of FSSIWRs, which produce perturbation to adjust the center frequency of the first passband. In order to control the second-passband center frequency, the complementary split-ring resonators (CSRRs) are etched on the surface of the resonator. The etched CSRRs can not only adjust the second-passband center frequency by changing the locations of the CSSRs but also produce a transmission zero (TZ) in the upper stopband of the second-passband. In addition, other five TZs are obtained by introducing source–load coupling, which highly improve the frequency selectivity. Finally, the proposed filter is fabricated and measured. The measured results agree well with the simulated ones.