Attenuation and surface roughness of electroplated waveguides

Measurements of the attenuations produced by air-filled silver-plated waveguides have been made at a frequency of 9 375 Mc/s before and after corrosion. The results suggest that plated surfaces are generally rougher than drawn ones. A detailed study has therefore been made of the surface roughness of various sizes of waveguide tubing when electroplated internally. The relative merits of several different types of electroplate, and the effects of variations in plating thickness and current density in the plating bath, have been determined.Although silver plating of waveguide components seems to be standard practice it is concluded that plating may not give the improvement in attenuation expected and is probably not worth while for many applications.