A COMPACT WIDEBAND BANDPASS FILTER USING SINGLE ASYMMETRIC SIR WITH LOW LOSS AND HIGH SELECTIVITY

In this letter, a novel compact wideband bandpass filter (BPF) using single asymmetric stepped-impedance resonator with one-step discontinuity is designed and fabricated. The first two resonant modes of the asymmetric SIR are coupled together and applied to create a wide passband. The proposed filter at center frequency f(0) of 4.2 GHz has very good measured characteristics including the bandwidth of 2.9-5.05 GHz (3-dB fractional bandwidth of 52%), average low insertion loss of 0.2 dB, and sharp rejection of 53 and 88 dB/GHz in lower and higher passband edges. Additionally, the wideband BPF has a smaller circuit size in comparison of previous works. (C) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 242-244, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24023