UWB BANDPASS FILTER BASED ON RING RESONATOR

Abstract

A new ultra-wideband bandpass filter is proposed, with a ring resonator and two stepped-impedance stubs to provide good wideband filtering performance and sharp rejection skirts. Interdigital coupled lines are placed at both ends of the ring resonator as input and output feed lines. The use of interdigital coupled lines makes it possible for the first three resonances of the ring resonator to be closer to wideband characteristics. By cutting apertures in the ground plane under the interdigital coupled lines, the coupling effect between the feed lines and the ring resonator can be increased, so that the passband characteristics can be improved. By adding two stepped-impedance stubs to the ring resonator, sharp rejection skirts can be obtained in the passband. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2047-2051, 2013