Investigation on a defected microstrip structure and applications in designing microstrip filters

Abstract

A new defected microstrip structure is proposed in this paper. By etching a simple U-shaped slot in the center of microstrip line, a very good bandstop characteristic is exhibited. Its resonant frequency is extracted by transmission line network analysis. At the same time, an accurate method of adjusting the resonant frequency is proposed to match the designed resonant frequency exactly. As advantages of this structure, the lower insertion loss in the passband, higher rejection level, and more simply integrated structure have been mentioned. The applications have been verified in the design of both microstrip dual-band bandstop and bandpass filters by experiment.

Acknowledgment

This work was supported by Tianjin Research Program of Application Foundation and Advanced Technology, China, under Grant 12JCYBJC10500.