Compact Cascaded Quadruplet Bandpass Filter Using Modified Coaxial Cavity Resonator with Q-Factor Improvement

품질계수가 향상된 변형된 동축 공동 공진기를 이용한 다단 Quadruplet 대역통과 여파기

  • Received : 2015.07.07
  • Accepted : 2015.11.19
  • Published : 2015.11.30


This paper presents a novel modified coaxial cavity resonator and its application to bandpass filters with compact size and improved quality factor(Q-factor). The proposed resonator is made up of ${\Gamma}-shape$ or curved four inner conductive posts within a single cavity, which provides quadruplet to realize bandpass filter. No metallic walls inside the cavity are required, and thus the utilization efficiency of the cavity space is improved. As a result, the unloaded Q can be approximately 15 % higher in comparison to the conventional coaxial resonator, or more than 35 % volume saving can be achieved while maintaining the similar Q-factor value with the conventional designs. In addition, due to the multiple cross-coupling occurring within the cavity, including the source-to-load coupling, four flexible transmission zeros can be created to realize different filtering functions. Simulations as well as experimental results of four- and eight-pole filters are presented to validate this attractive design concept. Good agreement between measured and computed results is obtained.


Coaxial Cavity Resonator;Q-Factor;Bandpass Filter;Miniaturization


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