Rectangular waveguide coupler with adjustable coupling coefficient using gap waveguide technology

Abstract

Gap waveguide is a promising alternative to traditional waveguide. One of the most important advantages of gap waveguide is that electrical contact between its subcomponents is not necessary. Therefore, it is flexible to adjust its performance by replacing part components of it without the need of reassembling the entire circuit. A slot coupled narrow-wall rectangular waveguide coupler with adjustable coupling coefficient is presented. Coupling slots with different inclined angles are realised in the replaceable narrow-wall coupling plate. By changing the coupling plate, the coupling coefficient can be adjusted flexibly. Corrugated edges are loaded on both sides of the replaceable plate to eliminate resonance maybe excited between the fixed metal plate and replaceable plate. A Ka-band prototype working at the frequency band from 30 to 40 GHz is successfully designed, manufactured and tested. Two replaceable coupling plates with coupling slots inclined of 15° and 45° are manufactured. The measured average coupling coefficient is, respectively, 18.5 and 9 dB. The measured return loss is >17 dB from 30 to 36.5 GHz and >12 dB from 36.5 to 40 GHz. The simulated and measured results agree well.