Bandpass filters with N + 1 transmission zeros using λ/4 resonator and λ/2 resonator
Published online by Cambridge University Press: 02 May 2018
Abstract
The present paper presents a novel method to cope with the difficulty that an N-order filter can introduce a maximum number of transmission zeros (TZs) – no more than N. The method is described by a coupling topology and realized by a regular fully canonical filter structure to increase one more TZ for an N-order filter without any filter size increase. Besides, the TZ shift property, as another advantage of the proposed topology, is investigated. The coupling topology consists of a group of fully canonical coupling nodes with the harmonic node (non-resonating node (NRN)) excited by a λ/4 resonator. Owing to the unique coupling topology and coupling node distribution as well as the inclusion of an NRN, N + 1 TZs are generated by an N-order bandpass filter, while all the TZs are close to the passband and far away from the harmonic passband resulting the highly selective passbands. For demonstration, two-, three-, and four-order filters are designed and measured with the experimental results that confirm the proposed technique.
Keywords
- Type
- Research Papers
- Information
- International Journal of Microwave and Wireless Technologies , Volume 10 , Issue 4 , May 2018 , pp. 401 - 404
- Copyright
- Copyright © Cambridge University Press and the European Microwave Association 2018
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