This chapter was aimed at introducing convenient models of excitation for antennas. The distributed excitation, that of a uniform plane wave, was introduced first. The localised excitation was considered next. It was concluded that practical reasons dictate the use of a few simple models of localised excitation, which can be used in most cases; the delta-function generator is one such possibility, and the TEM magnetic-current frill (usually changed to an approximately equivalent distribution of impressed electric field) is the other. An important addition to the standard treatment of excitation relates to relatively thick monopole antennas connected to metal plates of finite size and driven at the junction by a magnetic-current frill approximating the coaxial-line excitation. By a simple theorem the frill excitation is transferred to the wire, which enables the plate and the monopole to be analysed in the same manner as if the excitation were by a delta-function generator or a plane wave, i.e. an additional attachment mode or finer partitioning of the plate is avoided.

Inspec keywords: electric fields; coaxial cables; monopole antennas

Other keywords: metallic antenna; TEM magnetic-current frill; approximately equivalent distribution; metal plates; impressed electric field; localised excitation; metallic scatterers; thick monopole antennas; antenna excitation; uniform plane wave; coaxial-line excitation; excitation treatment; delta-function generator

Subjects: Single antennas