Analysis and Synthesis of Ttriplate Branch-Line 3dB Coupler Based on the Planar Circuit Theory

This paper is presented how to analyze and synthesize a triplate branch-line 3dB coupler based on the planar circuit theory, which takes into account the electromagnetic field disturbance at transmission line junctions and its mutual interaction. Moreover, the corresponding branch-line 3dB coupler analyzed and synthesized here is constructed practically and measured for 1-12GHz. Since the synthesized results agree well with the measured results, the validity and the usefulness of this planar circuit theory is confirmed.