Design of compact filtering rat-race hybrid with λ/2-resonators

Yun-Long Lu, Yi Wang, Changzhou Hua, Taijun Liu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


A novel compact filtering rat-race hybrid coupler with improved upper stopband is presented. Four coupled λ/2-resonator pairs are utilised to replace the λ/4- and 3λ/4-transmission lines in the conventional hybrid. Each coupled λ/2-resonator pair exhibits a bandpass filtering response and acts as a K-inverter. Eight resistors are placed at the centre of the λ/2-resonators to suppress the second-harmonic. For verification, a filtering rat-race hybrid is implemented with a centre frequency of 1.27 GHz and 20 dB rejection band of 2.73 f0. Good in-phase and out-of-phase characteristics are obtained. The proposed device has a simple circuit topology, compact size and good performance.
Original languageEnglish
Pages (from-to)1780-1782
Number of pages3
JournalElectronics Letters
Issue number21
Early online date15 Sept 2016
Publication statusPublished - 10 Oct 2016


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