Journal of the Institute of Electronics Engineers of Korea TC (대한전자공학회논문지TC)

The Institute of Electronics and Information Engineers (대한전자공학회)
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Analysis and Design Theory of Aperture-Coupled Cavity-Fed Back-to-Back Microstrip Directional Coupler

개구면 결합 공진기 급전 마이크로스트립 방향성결합기 해석 및 설계

  • Nam, Sang-Ho (School of Electrical and Electronic Engineering Chung-Ang University) ;
  • Jang, Guk-Hyun (School of Electrical and Electronic Engineering Chung-Ang University) ;
  • Nam, Kyung-Min (School of Electrical and Electronic Engineering Chung-Ang University) ;
  • Lee, Jang-Hwan (School of Electrical and Electronic Engineering Chung-Ang University) ;
  • Kim, Chul-Un (School of Electrical and Electronic Engineering Chung-Ang University) ;
  • Kim, Jeong-Phill (School of Electrical and Electronic Engineering Chung-Ang University)
  • Published : 2007.03.25
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Abstract

An analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler is presented for the efficient and optimized design. For this purpose, an equivalent network is developed, and simple but accurate calculations of circuit element values are described. Design equations of the coupler are derived based on the equivalent circuit. In order to determine various structural design parameters, the evolutionary hybrid optimization method based on the genetic algorithm and Nelder-Mead method is invoked. As a validation check of the proposed theory and optimized design method, a 10 dB directional coupler was designed and fabricated. The measured coupling was 10.3 dB at 3 GHz, and the return loss and isolation were 31.8 dB and 30.5 dB, respectively. The directional coupler also showed very good quadrature phase characteristics. Good agreements between the measured and the design specifications fully validate the proposed network analysis and design procedure.

개구면 결합 공진기 급전 마이크로스트립 방향성결합기의 특성을 해석하였고, 최적 설계를 위한 효율적인 설계 이론을 제시한다. 이러한 목적을 위해 단순하고도 정확한 등가 회로를 도출하였고, 도출된 등가 회로를 바탕으로 결합기의 설계 수식을 유도하였다. 여러 구조적 설계 변수를 결정하기 위해, 유전 알고리즘과 Holder-Mead 방법에 기반한 진화적 이종 최적화 방법을 사용하였으며, 제안한 설계 방식과 최적화 설계 방법의 타당성을 검증하기 위해 10 dB 방향성 결합기를 설계, 제작하였다. 측정된 결합기의 결합 계수는 3 GHz에서 10.3 dB 였고, 반사계수와 isolation은 각각 31.8 dB 와 30.5 dB 였다. 또한 출력단과 결합단 사이에 $90^{\circ}$ 위상 차이를 보였다. 측정치와 설계치의 일치도는 제안한 해석 방법과 등가 회로 및 최적화 설계의 타당성을 검증해 준다.

Keywords

References

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