Coupling characteristics of microstrip spiral resonators and the design of a 4-pole bandpass filter

摘要

A small-sized 4-pole 1.93 GHz bandpass filter (BPF) is designed by using microstrip spiral resonators. The frequency response of the fitter, simulated by using an electromagnetic solver, satisfies well the desired specifications. With appropriate arrangement of the resonators, new coupling characteristics between two neighboring spiral resonators are found, which can contribute to the realization of even smaller filters.