Improvement of stop-band performance of a CPW bandpass filter using DGS

摘要

A CPW-based bandpass filter (BPF) is designed in S-band by open ended series stubs. Two open ended stubs with opposite orientation are placed closely into a CPW line to offer greater field confinement. They provide band accept response with one attenuation zero. An enhanced selectivity is achieved by using four such stubs in symmetric manner. Defected ground structures (DGS's) are used to reject higher harmonics and to obtain a wide stop-band. To validate the design, a prototype was fabricated. In good agreement with the theoretical results, the measured results of the S-band bandpass filter achieve insertion loss of <0.2 dB, fractional bandwidth (FBW) of 67% with rising and falling edge selectivity of 35.9 dB/GHz and 45.7 dB/GHz respectively, and around 8-GHz stop-band. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:593-597, 2016