A Waveguide Directional Coupler with Interleaved Coupling Holes

A waveguide directional coupler with high directivity and broad bandwidth featuring interleaved coupling holes is proposed in this paper. It incorporates two WR-10 waveguides, and coupling is achieved via two interleaved rows of holes on their shared broad wall. Within the operating bandwidth of 65 GHz to 110 GHz, the coupling degree varies from 18.8 dB to 20.9 dB, the return loss of input port is better than 28 dB and isolation higher than 45 dB. This design doubles the distance between adjacent coupling holes, significantly reducing the manufacturing difficulty.