Design of a bandpass filter using hybrid planar waveguide resonator and stepped-impedance resonators

Abstract

A novel third-order bandpass filter (BPF) based on a hybrid planar waveguide resonator and stepped-impedance resonators (SIRs) is proposed in this article. The proposed filter is constructed by using one hybrid planar waveguide resonator and two stepped-impedance resonators. By controlling the resonant frequency and susceptance slope parameters of the resonator, a BPF has been realized by using different types of resonator with the same resonant frequency. Compared to classical microstrip resonators, a hybrid planar waveguide resonator can significantly enhance the selectivity of the filter. A detailed procedure for designing a BPF using a hybrid planar waveguide resonator and stepped-impedance resonators is given in this article. A third-order BPF is designed, fabricated, and measured. Good agreement between simulated and measured results verifies the proposed structure and design procedure.