摘要

A modified triangular loop resonator with an open-circuited stepped-impedance stub, which can generate two closely spaced passbands at 5.2 and 5.8 GHz, is analysed. For verification, the triangular loop resonators along with stub-loaded resonators (SLRs) are then employed to design a compact 2.4/3.5/5.2/5.8-GHz quad-band bandpass filter (BPF) for wireless local area networks as well as worldwide interoperability for microwave access applications. Each of the four centre frequencies in the proposed quad-band BPF is able to be controlled due to the design freedom.