Study of the waveguide elements for mm-wave traveling wave tube

Abstract

The use of a millimeter waves for future mobile networks demands a creation of broadband transceivers with output power more than 10 W. Only vacuum electron devices, in particularly, traveling wave tubes can provide those parameters. Because of the short wavelength, the reference dimension of the interaction system becomes close to 100 microns and skin layer depth reaches 0,4 micron. Its fabrication comes across with low surface roughness challenge. In this paper, we evaluate interaction system elements fabricated by electrical discharge machining. The surface roughness of the microdimensional slot in a brass plate is determined experimentally. Based on the experimental roughness value, a computer simulation of a folded waveguide, a perspective type of an interactive system for a millimeter band traveling wave tube has been carried out. It is found that the loss value on the 40-period waveguide due to the roughness increases by 80 % in comparison with the ideal surface of the waveguide walls.