Tuning of directional coupler with coupling along a wide wall

Results of calculating characteristics of a directional coupler comprising two waveguide segments coupled by a hole in the common wide wall are given. The calculation is based on approximate solution of the Maxwell equations at given boundary conditions. It is shown that to provide the given attenuation and the matching conditions the problem is reduced to the calculation of the waveguide conductivity and optimization of their geometric parameters. In analyzing an actual coupler it has been found that to attain a 3 dB attenuation with simultaneous matching it is neccesary to change the coupler geometry in the coupling hole area and introduce matching elements