Excitation of aircraft resonances using onboard HF antennas

The effectiveness of exciting the dominant symmetric and antisymmetric resonances on a testbed aircraft using the on-board HF antennas is investigated by using a numerical model. The external resonances of the aircraft are computed for various excitation geometries with the aircraft in the in-flight and ground-alert modes. The ground plane beneath the aircraft is assumed to be perfectly conducting. The surface currents induced on the aircraft are computed for four different HF antenna excitation configurations: (1) fin-cap antenna only, (2) fin-cap and nose antenna, (3) one wing-tip probe, and (4) two wing-tip probes. A method-of-moments solution for the skin current is obtained by modeling the aircraft as intersecting conductive bodies of revolution. The natural modes of the aircraft are obtained numerically, and the excitations of these natural modes by using various configurations of the HF antennas are investigated