Figure 1-2.Fields confined in all directions.
Waveguides are the most efficient way to transfer electromagnetic energy. WAVEGUIDES are
essentially coaxial lines without center conductors. They are constructed from conductive material and
may be rectangular, circular, or elliptical in shape, as shown in figure 1-3.
Figure 1-3.Waveguide shapes.
Waveguides have several advantages over two-wire and coaxial transmission lines. For example, the
large surface area of waveguides greatly reduces COPPER (I2R) LOSSES. Two-wire transmission lines
have large copper losses because they have a relatively small surface area. The surface area of the outer
conductor of a coaxial cable is large, but the surface area of the inner conductor is relatively small. At
microwave frequencies, the current-carrying area of the inner conductor is restricted to a very small layer
at the surface of the conductor by an action called SKIN EFFECT.