Design of wideband/dual-band bandpass filter using a vias and slots loaded sector circular patch resonator

摘要

In this paper, a novel patch resonator is proposed to realize wideband anddual-band bandpass filter (BPF) with small frequency ratio. The introductionof metallic vias and slots on the patch enables the flexible control of the resonantfrequencies of TM_(01), two degenerated modes of TM11, and TM_(21). Twostubs loaded on the patch and coupled with I/O feeding line can introduce twoadditional resonant modes, and facilitate the control of input/output couplingstrength. Owing to the different coupling relationships between the stubmodes and two degenerated modes of TM_(11), the transmission zeros (TZs)located at the center of passband can be eliminated or generated by alteringtheir resonant order, thus realizing wideband or dual-band operation. Fordemonstration, two prototypes are simulated, fabricated and measured. Goodagreement can be observed between simulation and measurement. Theimplemented wideband BPF has a passband from 1.85 GHz to 3.03 GHz withsix transmission poles (TPs). While the implemented dual-band BPF operatesat 1.8/2.45 GHz with three TPs within each band and two TZs between twobands. Small frequency ratio of 1.33 is achieved. Wide upper stopband and lowinsertion loss can be observed for both prototypes.