A broadband and compact asymmetrical backward coupled-line coupler with high coupling level

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• 作者：Rasool Keshavarz^a ; Masoud Movahhedi^a ; ^{Movahhedi@ieee.org} ; Abdolali Abdipour^b
• 关键词：Microstrip coupled-line coupler ; Asymmetrical coupler ; Backward broadband coupler ; Interdigital capacitor
• 刊名：AEU - International Journal of Electronics and Communications
• 出版年：2012
• 期刊代码：1_14348411
• 类别：cp
• 出版时间：July, 2012
• 卷：66
• 期：7
• 页码：569-574
• 文件大小：918 K

摘要

A new wideband asymmetric microstrip coupled-line coupler with 3 dB coupling value and quadrature phase difference is presented. Compared with the conventional edge-coupled couplers, this structure, consisting of two different transmission lines (interdigital and conventional microstrip transmission lines) as coupled lines, achieves wider operating bandwidth and larger coupling level. The coupled-line length of the proposed structure is approximately 位_g/4. To characterize the structure, an equivalent circuit model has been established. A 3 dB designed and fabricated coupler with 0.2 mm spacing between coupled lines exhibits an amplitude balance of 2 dB from 2.2 GHz to 4.2 GHz. Good agreements between the full-wave simulation and equivalent circuit model results has been achieved and verified the effectiveness of the proposed circuit model. Also, measurement results have been presented.