A Cross-Guide Waveguide Directional Coupler With High Directivity and Broad Bandwidth

A cross-guide waveguide directional coupler (patent pending) with high directivity and broad bandwidth is proposed in this letter. It consists of two rectangular waveguides (called main waveguide and branch waveguide) crossing at a certain angle and sharing a common broad wall. High directivity is achieved by adding metal inserts in the branch waveguide in the coupling region near the crossed round-ended slots. For verification purpose, a sample coupler has been designed, manufactured and measured. The measured results show that the sample coupler has a directivity greater than 28 dB over the full waveguide bandwidth.