A Flat-Passband Microstrip Filter With Nonuniform-Q Dual-Mode Resonators

作者:Qiu, Liang-Feng*; Wu, Lin-Sheng; Yin, Wen-Yan*; Mao, Jun-Fa
来源:IEEE Microwave and Wireless Components Letters, 2016, 26(3): 183-185.
DOI:10.1109/LMWC.2016.2525017

摘要

A compact lossy microstrip bandpass filter is realized with flat passband and high selectivity, using the method of nonuniform Q. Two dual-mode resonators are utilized. The Q-factor of oddmode can be properly reduced by loading resistors over the symmetric plane of each resonator, with the even-mode Q unchanged. The geometric and resistance parameters are determined by the derived formulas and optimization. The 0.2 dB bandwidth of the fabricated prototype is improved by 62% when compared with the uniform-Q counterpart. The equivalent Q-factor is as high as 970, which is extracted from measurement.