Null field formulations for dielectric-coated antennas

Null field formulations utilizing a generalization of the extended boundary condition method of Waterman are presented for dielectric-coated antennas of arbitrary but smooth shapes. Spherical, prolate spheroidal and spherically capped cylindrical antennas are solved as examples. Their power radiation patterns and input conductances are plotted as functions of coating thickness. The dielectric coating effectively increases the antenna size. Furthermore, it is shown that an eccentric coating can produce a considerable shift in the power radiation patterns.