Alteration of the Surface Current on a Missile by the Presence of an Exhaust Plume

This paper presents an analysis of a missile with an exhaust plume when exposed to an incident electromagnetic plane wave at an arbitrary angle of incidence. Both homogeneous and axially inhomogeneous plumes are considered. For the inhomogeneous case, the AeroChem low altitude plume program is used to provide realistic values of the electrical properties along the length of the plume. In the analysis, the missile and the plume are assumed to be thin when compared to the length of the missile and the wavelength of the incident radiation. Conventional numerical methods developed for thin-wire antennas are used to determine the current in the missile and the plume, and the effect the plume has on the current is examined. Field patterns for aperture coupling at specific points on the missile are also presented. A limited comparison with measured results is presented.