A varactor tuned branch-line hybrid coupler

  title={A varactor tuned branch-line hybrid coupler},
  author={E. Fardin and Kamran Ghorbani and A. S. Holland},
  journal={2005 Asia-Pacific Microwave Conference Proceedings},
  pages={4 pp.-}
This paper introduces a novel branch-line 90/spl deg/ hybrid coupler incorporating varactor diodes which allow tuning of the frequency response. A design covering the DCS, PCS and IMT2000 cellular frequency bands (1710-2170 MHz) is presented. Given a varactor tunability of 2.5:1, simulations suggest 20 dB return loss and 3/spl plusmn/1 dB coupling is achievable across each transmit and receive sub-band by tuning the varactors. These results offer an improvement over a conventional single… CONTINUE READING
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