AUTHOR=Zhang Zhonghai , Zhao Yuekai , Chen Lin , Fang Zhihua , Wu Aiting , Zhang Pengquan 

TITLE=A Tunable low Pass Filter Based on Transmission Lines With Tunable Input/Output Impedance

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.872204

DOI=10.3389/fphy.2022.872204

ISSN=2296-424X

ABSTRACT=A tunable low pass filter(TLPF) based on the tuning of input/output impedance was presented in this letter. The TLPF was mainly consisted of improved quarter-wavelength stubs. The input/output impedance of the improved quarter-wavelength stubs can be tuned in certain range. The design procedure of this TLPF was derived from the filters based on the quarter-wavelength transmission stubs. Through the tuning of the input/output impedance of the transmission lines, the cut-off frequency of TLPF can be adjusted in certain range. The TLPF has relatively good designability and can be easily designed to meet other performance. Finally, a TLPF was designed, fabricated and measured. The measured results verify the effectiveness of the design method.