Improved Narrow-Wall Short Slot Coupler Design Exhibiting Significant Increased Bandwidth and Low Cost Production

A novel `short-slot´ coupler design variant is introduced to provide high performance over a substantial increased operating bandwidth compared with the state-of-the-art. It is based on an optimised overmoded coupling region that is associated with appropriate waveguide transformers to match the dedicated standard rectangular waveguide ports. The established single acting structure is supported by the design capability of effective EM CAD methods and facilitates low cost production by standard milling techniques. Theoretical and experimental results of 3dB couplers at 26GHz - covering a frequency band of 25% with a coupling variation of less than ±0.25dB - and at 30GHz covering 20% bandwidth (with a coupling variation of less than ±0.1dB) prove the validity of the approach.