Dual-Band Bandpass Filter with Low Insertion Loss Using Simple SIR Resonator

In this paper, a new dual-band bandpass filter with low insertion loss and compact size is presented. The study focuses on the resonance features of mixed electromagnetic coupling and cross coupling. The system utilizes a pair of dual-resonance resonators (DRRs) with mixed electromagnetic coupling to generate two signals of different frequencies. It then employs an open-ended stepped-impedance resonators cross-coupled with short-circuit stepped impedance DDRS to produce transmission zero. The analysis results indicate that the open-ended stepped-impedance resonator generates a transmission zero that is located close to the passband. This leads to a reduction in out-of-band insertion loss and enables the realization of a wide passband bandpass filter.