Journal of South China University of Technology (Natural Science Edition) ›› 2010, Vol. 38 ›› Issue (10): 14-18，23.doi: 10.3969/j.issn.1000-565X.2010.10.003

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

Source-Load Coupling Filter with Four Transmission Zero Points

Chu Qing-xin  Fan Li   

  1. School of Electronic and Information Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China
  • Received:2010-03-24 Revised:2010-04-06 Online:2010-10-25 Published:2010-10-25
  • Contact: 褚庆昕（1958-），男，教授，博士生导师，主要从事射频电路与天线研究． E-mail:qxchu@scut．edu．cn
  • About author:褚庆昕（1958-），男，教授，博士生导师，主要从事射频电路与天线研究．
  • Supported by:

    NSFC-广东省自然科学联合基金资助项目（U0635004）; 广东省自然科学基金资助项目（60571056）

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Abstract:

In order to obtain bandpass filters with high selectivity,small size,low loss and low cost,a compact source-load coupling filter with four transmission zero points is presented,which uses a half-wavelength multi-mode T-shaped resonator to reduce the filter size and to facilitate the bandwidth design.Then,based on the generation mechanism of transmission zero points,a controllable coupled element is inserted in the region between the input and the output ports to generate multiple paths for signal transmission.Thus,four controllable zero points independent of bandwidth and central efficiency are generated.Moreover,a compact microstrip bandpass filter with four transmission zero points is designed and fabricated,with the insertion loss and the bandwidth respectively reaching 1.4 dB and 10%.Finally,the filter is tested and the results accord well with the simulated ones.It is thus concluded that the proposed design method is feasible.

Key words: bandpass filter, source-load coupling, T-shaped resonator, transmission zero point, coupling capacitor, coupling line