–3dB Coupler in Waveguide Systems
Figure 1: -3dB-coupler
A -3dB-coupler divides the power arriving on a waveguide up into two equally big portions. At this the phase of the diverted waveguide is shifted by 90°. This phase shift is indicated by blue directional arrows (E field) in the shown figure.
This phase turn is used in many applications (e.g.: Duplexer or Filter) specifically.
To match the lines with the couplers other geometry of the cross-cut a conical deepening is often attached in central place. This is recognizable of the outside also.
The not uses port ist closed by a dummy load.