ABSTRACT
Any structure that transports electromagnetic waves can be considered as a waveguide. Waveguides that consist of conductors and dielectrics are called metal waveguides. Waveguides that consist of only dielectric materials are called dielectric waveguides. Metal waveguides use the reflective properties of conductors to contain and direct electromagnetic waves. In most cases, they consist of a long metal cylinder filled with a homogeneous dielectric. Both transmission lines and waveguides are capable of guiding electromagnetic signal energy over long distances, but waveguide modes behave quite differently with changes in frequency than do transmission-line modes. Metal waveguides have the simplest electrical characteristics of all waveguide types, since their modal eigenvalues are functions only of the cross-sectional shape of the metal cylinder and are independent of frequency. Although waveguide modes are not plane waves, the ratio of their transverse electric and magnetic field magnitudes are constant throughout the cross sections of the metal waveguides, just as for plane waves.
