Miniaturized branch-line coupler with coupling-dependent dual-frequency operation

Tse Yu Chen, Pei-Ling Chi, Ting Tsan Lin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations


A miniaturized branch-line coupler that is able to operate at two arbitrary frequencies is presented in this paper. The dual-band frequency ratio depends on the coupling coefficient in the proposed transmission line element. It will be shown later that the dual-band separation decreases as the coupling strength increases. By replacing the traditional quarter-wavelength lines with the proposed artificial transmission lines of a prescribed coupling coefficient, a size-reduced branch-line coupler can be implemented at dual frequencies of interest. An example of the 0.9- and 1.8-GHz branch-line coupler, which corresponds to a band ratio of 2, is experimentally developed and characterized. The presented coupler occupies only 44% footprint of the conventional coupler operating at the lower frequency of the dual-band operation. Excellent agreement between the simulated and measured results is obtained.

Original languageEnglish
Title of host publication2013 Asia-Pacific Microwave Conference Proceedings, APMC 2013
Number of pages3
StatePublished - 1 Dec 2013
Event2013 3rd Asia-Pacific Microwave Conference, APMC 2013 - Seoul, Korea, Republic of
Duration: 5 Nov 20138 Nov 2013

Publication series

NameAsia-Pacific Microwave Conference Proceedings, APMC


Conference2013 3rd Asia-Pacific Microwave Conference, APMC 2013
CountryKorea, Republic of


  • Branch-line coupler
  • coupled line
  • dual-band

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