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Modeling and Validation of Loose Coupler by Using DGS in Branch line Coupler


1Tamasi Moyra, 2Susanta Kumar Parui, 2Santanu Das

1Department of Electronics and Communication Engineering,

 National Institute of Technology, Agartala

2Department of Electronics and Telecommunication Engineering,

 Bengal Engineering and Science University, Shibpur, www.becs.ac.in, India

 Received November 9, 2012


Abstract. A novel planar 10 dB loose branch line coupler is proposed for application to the 2.5 GHz centre frequency. This proposed coupler is implemented with rectangular ring headed dumbbell shaped Defect Ground Structure (DGS) along with conventional microstrip transmission line. Design of this conventional branch line coupler with DGS provides more design flexibility. Use of DGS underneath the microstrip line increases the electrical length of microstrip line, provides slow wave characteristics and increases the impedance of the microstrip line. In this paper one high impedance microstrip line is easily implemented by using proposed DGS structure which is required for designing the loose coupler. Finally, the compact branch line 10 dB loose coupler is designed, fabricated and measured. The experimental results are in good agreement with predicted simulated values.

Keywords: branch line coupler, Defect Ground Structure (DGS), 10 dB loose coupling, microstrip line.