Stripline forward‐wave directional coupler based on double multi‐via mushroom and short‐circuited branch line

Abstract

A stripline forward‐wave directional coupler is proposed using periodical double multi‐via mushroom structures and short‐circuited branch lines in this paper. By adding the short‐circuited branch lines to the coupled lines and the patch of the upper or lower mushroom structure, the operating bandwidth is enhanced for the unit cell design. The even/odd mode phase difference of one unit cell is located within 20 ~ 30° from 6.1 to 6.7 GHz with an acceptable even/odd mode Bloch impedance mismatching. Finally, a prototype is fabricated by multi‐layer printed circuit broad technology and measured. The agreement is achieved between the simulated and measured results.