Novel Wideband Bandpass Filter with Dual Notched Bands Using Stub-Loaded Resonators

In this letter, a novel wideband bandpass filter with dual notched bands using stub-loaded resonators is proposed. By using the signal interaction of two transmission paths, a wideband passband and two notched bands can be independently achieved and designed. By cascading two back-to-back vertical transitions, a six-pole wideband filter with equal ripple filtering response is synthetically analyzed. The dual notched bands are controlled by the even- and odd-mode resonant frequencies of the stub-loaded resonator. As a design example, the proposed wideband filter with dual notched bands is simulated and fabricated. The desired wideband filtering response is experimentally validated, and two notched bands are measured at 3.04 and 3.85 GHz, respectively.