A Directivity-Enhanced Directional Coupler Using Epsilon Negative Transmission Line
A Directivity-Enhanced Directional Coupler Using Epsilon Negative Transmission Line
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DOI：
10.1109/tmtt.2012.2216283
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发表时间：
2012-09
影响因子：
4.3
通讯作者：
A. Pourzadi;A. Attari;M. S. Majedi
中科院分区：
文献类型：
--
作者：
A. Pourzadi;A. Attari;M. S. Majedi
本文提出了一种利用ε负（ENG）传输线的高指向性平行耦合器。通过偶模和奇模分析表明，在并联耦合线耦合器中使用ENG传输线，可以使偶模和奇模相速度在所需频率下相等。因此，理论上耦合器的指向性可以是无限的。给出了耦合器电路模型及其集总元件的封闭关系。此外，还提出了该耦合器微带实现的设计步骤。在此基础上，设计了一个2ghz的10db ENG定向耦合器，并进行了全波仿真验证。制作了该耦合器，并给出了测量结果。实验结果表明，在1.95 GHz时，最大指向性接近40 dB。
In this paper, a high directivity parallel coupled line coupler using the ε negative (ENG) transmission line is proposed. With the aid of even- and odd-mode analysis, it is shown that by using ENG transmission lines in a parallel coupled line coupler, the even- and odd-mode phase velocities can become equal at a desired frequency. Hence, the directivity of a coupler can be infinite theoretically. The coupler circuit model and closed-form relations for lumped elements of this model are presented. In addition, a design procedure for microstrip implementation of this coupler is proposed. Based on the proposed procedure, a 10-dB ENG directional coupler is designed at 2 GHz and validated by full-wave simulations. This coupler is fabricated and measurement results are presented. Experimental results show maximum directivity of nearly 40 dB at 1.95 GHz.