Compact multi-band transversal bandpass filters with source–load coupling

Abstract

A method in designing multi-band bandpass filter is proposed in this paper. This design employs source and load cross-coupling technique and transversal structure with stub-loaded dual-mode resonators. The proposed filters are miniaturized by using stub-loaded dual-mode resonators, and half of the resonators are reduced compared with traditional SIR filters. What is more, the dual-mode resonators and the source–load cross-coupling can introduce more transmission zeros to improve frequency selectivity. It is demonstrated by the simulated and measured results that the novel filters have the advantages of low in-band insertion loss, good out-band rejection, and compact size. This proposed filter can be applied in the microwave circuits and wireless communication systems.

Keywords:

• microwave circuit
• filter
• multi-band
• transversal structure

Acknowledgment

This work is supported by National Natural Science Foundation of China (Grant No. 61201004) and the Fundamental Research Funds for the Central Universities (ZYGX2011J011).