SIMPLIFIED ANALYSIS OF COATED WIRE ANTENNAS AND SCATTERERS

A simple prescription due to Popovic enables any analytical or numeric al formulation for scattering or radiation by arbitrary bare-wire ante nnas of circular cross-section to be used for antennas having an elect rically-thin coating of dielectric and/or magnetic material. The presc ription relies on transforming any coating to the equivalent magnetic one and treating it as an impedance per unit length. It is applied wit hin an existing analytical treatment for scattering by a bare half-wav e dipole to obtain predictions for the radar cross-section of dielectr ic-coated dipoles. It is also used with the bare-wire moment-method co de NEC to derive the current distribution on a coated monopole antenna . In both cases good agreement with measurement is obtained. The limit s of the underlying theory are explored by comparing the results of th is prescription with those obtained by an explicit moment-method treat ment of a dielectric coating.