Electromagnetic Waves in Metal Tubes Filled Longitudinally with Two Dielectrics

Abstract

The propagation of e-m waves is investigated: (1) in a rectangular metal tube half-filled longitudinally with a dielectric; (2) in a cylindrical dielectric guide of radius $a$, surrounded by a coaxial metal tube of radius $b$. In (1) the waves are of the longitudinal-section type; for high frequencies they are confined to the medium of higher dielectric constant. The problem is discussed also with the model of the criss-cross component waves. In (2) the waves are linear combinations of $E$ and $H$ waves. The case of axial symmetry is considered, in which there are simple $E$ and $H$ waves. For ${E}_{0}$ a critical wave-length exists, depending only on the dimensions of the inner dielectric, and on the dielectric constants, below which the system behaves more or less as a dielectric guide in free space, and above which as an ordinary hollow tube. For ${H}_{0}$ this critical wave-length depends also on the ratio $\frac{b}{a}$. The case in which the external medium has a higher dielectric constant is also briefly investigated.