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.