volume | PIER Journals

Abstract

In this letter, a novel compact broadband and high rejection bandpass filter (BPF) with the source-load coupling is proposed using the triple-mode stub-loaded resonator. The resonator is formed by attaching one T-type open stub at the center plane and two identical short-circuited stubs symmetrical to high impedance microstrip line. It can generate one odd-mode resonant frequency f_m2 and two even-mode f_m1, f_m3 in the desired band. The f_m2 can be approximately determined by the high impedance microstrip line. The short-circuited stubs and T-type open stub can be applied not only to separately adjust the f_m1 and f_m3 while the two other ones keep relatively stationary, but also to separately create transmission zero near the lower and upper cut-off frequencies, leading to a high rejection skirt. As a result of the source-load coupling, two transmission zeros in the upper-stopband are generated to deepen and widen the upper-stopband. A high rejection BPF with the fractional bandwidth 76% is simulated, fabricated and measured. The measured results agree well with the EM simulations.

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Dr. Hong-Wei Deng

Dr. Bin Liu

Dr. Yong-Jiu Zhao

Dr. Xue-Shun Zhang

Dr. Wen Chen