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.