Guiding Those Waves

64 EE December 1988 GUIDING THOSE WAVES by W.D. Higgins An increasing number of engineers have to consider processing signals in the gigahertz frequency range: satellite TV, information/data systems, point-to-point microwave links, and radar are but a few examples of fields where a basic understand- ing of the operation of waveguides is required, and where this brief "guide to waveguides" may prove useful as an introduction. A waveguide is essentially a precision- engineered length of hollow, usually rec- tangular, aluminium, invar, copper or brass (70/30 and 90/10) tubing that serves to carry microwave RF signals. Whereas professional-grade coaxial cable is used up to about 3 GHz with considerable attenuation, certain types of waveguide are suitable for carrying RF signals at frequencies of 50 GHz and higher, at an insertion loss that remains negligible even for relatively long runs. Waveguide technology can be treated as a very fine art, but is in principle very similar to conve...