Journal of South China University of Technology (Natural Science Edition) ›› 2011, Vol. 39 ›› Issue (7): 21-25,31.doi: 10.3969/j.issn.1000-565X.2011.07.004

• Electronics, Communication & Automation Technology • Previous Articles     Next Articles

Design of Novel Dual-Band Branch-Line Coupler with Wide-Range Frequency Ratio

Chu Qing-xin  Sun Jing-jing  Lin Feng   

  1. School of Electronic and Information Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China
  • Received:2011-01-24 Revised:2011-03-21 Online:2011-07-25 Published:2011-06-03
  • Contact: 褚庆昕(1958-) ，男，教授，博士生导师，主要从事射频器件与电路的理论与技术、计算电磁学以及现代通信天线研究． E-mail:qxchu@scut.edu.cn
  • About author:褚庆昕(1958-) ，男，教授，博士生导师，主要从事射频器件与电路的理论与技术、计算电磁学以及现代通信天线研究．
  • Supported by:

    NSFC-广东省自然科学联合基金资助项目( U0635004) ; 国家自然科学基金青年科学基金资助项目( 60801033) ;广东省自然科学基金重点项目( 07118061)

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Abstract:

As the conventional 3dB dual-band branch-line coupler is of narrow operation frequency ratio,the method to design a novel dual-band branch-line coupler loaded with stepped impedance stub lines is presented. The adoption of stepped impedance stub lines increases the design degree of freedom and reduces the restriction from the physical realization of impedance range. Thus,a 3 dB dual-band branch-line coupler with wide-range frequency ratio ( 1. 7 ～ 6. 3) can be obtained. Moreover,a 3 dB microstrip branch-line coupler operating at 2. 4 /5. 8 GHz WLAN bands is simulated and fabricated to verify the proposed design method. The results show that,as compared with the conventional Ⅱ-shaped dual-band branch-line coupler,the novel coupler achieves a stub-size reduction up to 25. 1%. The simulated results accord well with the measured ones,which means that the proposed design method is feasible.

Key words: coupler, dual-band branch-line coupler, stepped impedance, frequency ratio