Design of high‐performance broadband multisection symmetrical 3‐DB directional couplers

The influence of discontinuity effects on the performance of symmetrical multisection coupled‐line directional couplers designed in a stripline technique has been comprehensively investigated, for the first time. It has been shown that the connections between coupled‐line sections introduce parasitic reactances which deteriorate the isolations and return losses of designed couplers and also that the recently developed method of capacitive compensation can be applied to improve couplers' performance. A three‐section symmetrical 3‐dB directional coupler has been designed and measured. The measurement results validate the presented analyses.