Wideband directional coupler based on zigzag coupling and wedge structure for isolation enhancement

Abstract

This paper presents the design of wideband directional coupler with enhanced isolation performance. Studies show that introducing the zigzag coupling releases the phase-velocity difference between the even-and odd-mode in the coupling region, thus improving the directivity. To further improve the performance, wedge structure is proposed, and therefore, a wideband coupled-line directional coupler is developed with enhanced isolation responses. The presented coupler characterizes simple architecture, planar layout, symmetric topology, symmetric coupling and isolation responses that are the basic differ-