General properties of dielectric guides

Electrical signals are at present transmitted by radio with energy travelling freely in space, and by transmission lines with energy confined to the conductors. A new conception is that of dielectric guides, employing new means for determining the path of the signals and seemingly able to provide new methods of transmission. The dielectric guide may consist of a metallic tube to one end of which high frequency signals are applied. The signals remain inside the tube, which exclude external perturbations. No second conductor is required. The method is applicable only to very short waves, of wavelength of the same order as the diameter of the tube. The critical frequency can be reduced by filling the tube with insulation of high dielectric constant. Under certain conditions, dielectric guides may consist of dielectric without any metallic envelope. An outline is given of the treatment developed by J. R. Carson, S. P. Mead, and S. A. Schelkunoff, which indicates the existence of numerous types of waves having different properties as regards critical frequencies and variation of attentuaion.