Compact Dual-Band Bandstop Filters Using Stepped-Impedance Resonators

This work presents a compact dual-band bandstop filter (DBBSF) that features two controllable stopbands at desired frequencies. Stepped-impedance resonators are utilized to realize the dual-stopband characteristics, and reduce size. The synthesis method is developed. An experimental circuit is fabricated and evaluated to validate the design concept. Measurements correlate well with the simulation results, and the size is 12.6% less than that of a standard DBBSF.