Design of wide band directional coupler by ridged rectangular waveguide for large power capability

By the theory of Bethe-hole coupling, a new modified multi-hole directional coupler based on the ridged rectangular waveguide is proposed in this paper. Three kinds of coupling-hole configurations, namely, circular hole, triangle hole and square hole, are investigated for realizing the wide band coupling between two different transmission lines. After extensive simulation and analysis, square hole is chosen as it exhibits best bandwidth performance. The coupling coefficient is 40 dB with a deviation smaller than 2 dB. The proposed coupler can be a promising candidate for application scenarios where flat coupling, high directivity, high power capacity and broad band width properties are desired.