Methods for modeling wire antennas loaded with shielded networks

Wire antennas are often loaded with lumped circuits in order to control or alter one or more of the antenna's characteristics. Shielding these circuits forces the load to manifest itself to the antenna from a small aperture. This ensures that the laws of circuit theory may be used in an analysis to characterize the load, rather than Maxwell's equations, simplifying the computations. To this end, four configurations of lumped loads are used in place of the antenna's shielded networks in the analysis of the loaded wire. Two of the lumped load configurations are specific to an aperture-coupled shielded network presented in this paper. Two other configurations considered, however, are physically representative of a large class of wire antenna loads. Data obtained from analyses based upon the models introduced and from measurements are presented for comparison.