A novel dual-mode dual-band bandpass filter with DGS structure

Abstract

A novel dual-mode dual-band filter with perturbative resonators and DGS structures is proposed. The specific perturbative resonators consist of a conventional microstrip square ring resonator and square patch resonator located by conductor patch or corner-cut elements. The conductor patch is called the main perturbation element, while the corner-cut is called reference perturbation element. For high stopband rejection, DGS structure is introduced. A bi-interdigital coupling structure is used to provide a large external coupling as well as source-load coupling. Two proper degenerate modes in the lower and upper passbands can be excited and controlled by both dimension of main perturbation elements and reference perturbation elements. Finally the specific filter generate the 3dB bandwidths in the lower and upper passbands are 420MHz(13% at 3.2GHz) and 1GHz(10% at 9.45GHz). This study focuses on the analysis and design of the proposed dual-band BPF as well as the simulation of it.