Bandpass Filters Designed by Transmission Zero Resonator Pairs with Proximity Coupling

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Original languageEnglish
Article number7920380
Pages (from-to)4103-4110
Journal / PublicationIEEE Transactions on Microwave Theory and Techniques
Issue number11
Online published5 May 2017
Publication statusPublished - Nov 2017


The concept of transmission zero resonator pair (TZRP) is used in this paper. Based on this TZRP, a new method to induce a passband is demonstrated, by which different types of bandpass filters can be designed. The proposed TZRP is structured by a pair of resonators with different resonant frequencies, which lead not only to two transmission zeroes, but also to a transmission pole between them. Passband filters can then be built by designing the proximity coupling between the TZRPs, as the TZRP works as a basic resonant element. The passband of these filters can be flexibly controlled by the resonators of TZRPs, which determine the locations of the transmission zeroes and poles. By carefully allocating the transmission zeroes, high selectivity and large out-of-band rejection can be realized. This design method is applied to design filters in two different transmission media, namely, microstrip line and rectangular waveguide. Simulated and measured results demonstrate the effectiveness of this new approach of bandpass filter design. The designed filters have the properties of small size, easy fabrication, low cost, and low loss.

Research Area(s)

  • Bandpass filter, microwave filter, transmission zero resonator pairs (TZRPs), transmission zeroes, waveguide filter