WT4 Millimeter Waveguide System: Waveguide Design and Fabrication

The waveguide medium is composed of a string of 60 mm internal diameter, 9 m long, flanged dielectric-lined and 4.4 m long helix waveguide sections. Dielectric-lined waveguide consists of a copper-plated steel tube, the inner surface of which is lined with a thin dielectric layer. Helix waveguide consists of a steel tube encompassing an insulated copper wire which is helically wound and is cast within the steel tubing with an epoxy. Dielectric-lined waveguide was selected to be the principal transmission medium, comprising approximately 99 percent of the total 1873 waveguide length. The remainder of the transmission medium consists of helix waveguide sections deployed at 800 m intervals. In this paper the factors leading to the choice of dielectric-lined waveguide as the principal waveguide medium will be reviewed. In addition, the designs and fabrication techniques associated with each type of waveguide will be discussed.