Transformer based high power directional couplers

Directional couplers have been used commonly in RF systems for measurement of several critical parameters. The type of application, operational frequency and power handling capability are among the important factors that the design of the directional coupler. Conventional directional couplers are designed as four port couplers where tow ports are used for sensing the forward and reflected signals. There is an extensive literature in the design of planar four port directional couplers. However, the available literature in the design of high power directional couplers using lumped components is very limited.