Adjustable Directional Couplers

The characteristics of directional couplers with coupling factors of 3.0 and 12.6 dB at 1.3 GHz are calculated. The devices are based on 165.1 × 82.5 mm2 rectangular waveguides coupled through their common narrow walls. In both devices, the coupling factor can be varied within ±1 dB relative to its nominal value (at a directivity of no less than 25 dB). The adjustment is accomplished by shifting movable shorts in auxiliary 276.0 × 82.5-mm2 waveguides connected to the coupler narrow walls from two sides and placed opposite to the coupling apertures. Simulation results obtained on reduced-scale devices confirm the numerical data.