The Resonance Mode Theory for Exterior Problems of Electrodynamics and Its Application to Discrete Antenna Modeling in a Frequency Range

The problem under consideration here is that of building a versatile discrete antenna model in a frequency range. The eigenfunction (mode) expansion or singularity expansion method (SEM) is used in working out the problem. A detailed substantiation of SEM is provided and an expression determining the dependence of mode amplitudes on exterior source fields is derived. A simple example is provided in support of the theory. The SEM is used in inquiring into the frequency dependence of antenna-generalized matrix entries. It is intimated that all of the matrix entries contain resonance factors and factors that are Hankel transforms of radial coordinate functions. A sampling theorem, which is a generalized extension of the classic sampling theorem, is used for the Hankel transform. The application of the generalized sampling theorem completes the process of building a versatile discrete antenna model in a frequency range.