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

作者：Keshavarz Rasool; Movahhedi Masoud^*; Abdipour Abdolali

来源：AEU-International Journal of Electronics and Communications, 2012, 66(7): 569-574.

DOI：10.1016/j.aeue.2011.11.009

• Microstrip coupled-line coupler
• Asymmetrical coupler
• Backward broadband coupler
• Interdigital capacitor

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 lambda(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.

• 出版日期2012