A Novel Miniaturized SISL Bandstop Filter with High Rejection Based on Dual-Mode Resonator

A miniaturized substrate integrated suspend line (SISL) bandstop filter with high attenuation is proposed in this paper. To realize a higher rejection level, a novel dual-mode resonator is proposed and studied. The dual-mode resonator achieves large capacitance to ground and coupling with the transmission line, which enables the notch filter to achieve high performance while achieving miniaturization. In addition, the proposed dual-mode resonator can realize the high-order bandstop rejection conveniently by series connecting the resonators. To verify the proposed theory, a 4
^th
-order bandstop filter was designed, fabricated, and tested. Measured results agree well with simulated data.