Design of a miniaturized branch line coupler using common defected ground structure

A design of size-reduced 90° branch line coupler (BLC) is described in this work. A common defected ground structure (CDGS) is adopted to design the coupler. Common DGS patterns are realized on the common ground plane of double-sided microstrip lines of which ground planes are attached to each other back-to-back. The CDGS patterns play a great role in size-reduction of microwave circuits. As an example, a BLC is designed, fabricated and measured at 1GHz for the verification of the size-reduction using CDGS. The size of the fabricated coupler is less than 50% of the normal one without any critical degradation in performances. The measured S-parameters well agree with the simulation results.

[1]  Quan Xue,et al.  A novel microstrip ring hybrid incorporating a PBG cell , 2001, IEEE Microwave and Wireless Components Letters.

[2]  Dongsu Kim,et al.  Design of Dual-Band Bandpass Filter Using DGS With Controllable Second Passband , 2011, IEEE Microwave and Wireless Components Letters.

[3]  C. Caloz,et al.  Vertical microstrip transition for multilayer microwave circuits with decoupled passive and active layers , 2006, IEEE Microwave and Wireless Components Letters.

[4]  Jong-Sik Lim,et al.  Application of defected ground structure in reducing the size of amplifiers , 2002 .

[5]  T. Itoh,et al.  High efficiency power amplifier with novel PBG ground plane for harmonic tuning , 1999, 1999 IEEE MTT-S International Microwave Symposium Digest (Cat. No.99CH36282).

[6]  Jong-Sik Lim,et al.  Design of low-pass filters using defected ground structure , 2005, IEEE Transactions on Microwave Theory and Techniques.

[7]  Tae-Yeoul Yun,et al.  Uniplanar one-dimensional photonic-bandgap structures and resonators , 2001 .

[8]  Y. E. Yang,et al.  Modeling and analysis of vias in multilayered integrated circuits , 1993 .