MICROSTRIP BANDSTOP FILTER USING A DUAL-MODE SQUARE LOOP RESONATOR

Abstract

Dual-mode microstrip bandstop filter, which has an inductive or capacitive perturbation element located at one of its corners, with a 90 degrees-bended lambda/4 microstrip feeding line is proposed. The degenerate mode splitting of a conventional dual-mode square loop resonator and the coupling coefficient between these modes are investigated. The filter characteristic is changed by the perturbation size. Finally, a novel dual-mode microstrip bandstop filter is designed and realized using degenerate modes of dual-mode microstrip square loop resonator. Two filters are designed, fabricated, and measured to demonstrate the validity of the proposed bandstop characteristic. (C) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 147-150, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23967