Electromagnetic Waves in Hollow Metal Tubes of Rectangular Cross Section

The theory of the transmission of electromagnetic waves in hollow conducting pipes of rectangular cross section is derived for perfectly conducting and for imperfectly conducting materials. Special attention is given to the type of wave that has only one transverse and everywhere parallel component of electric intensity, and the results of experiments on this wave are reported. Expressions for the attenuation of the different types of waves allow comparisons to be made with corresponding waves in a pipe of circular cross section. In a rectangular pipe, no wave has been found whose attenuation decreases indefinitely as the frequency is increased, as does the H0wave in a circular pipe.