Electromagnetic effects associated with hypersonic re-entry vehicles

A summary is given of the factors affecting electromagnetic wave transmission and reception in connection with remote controlled guidance, telemetry, voice communication, and radar tracking of a hypersonic, re-entry vehicle. The emphasis of this paper is on the effects of the ionized shock layer, about the re-entry vehicle, on wave propagation to and from the vehicle. Generalized curves are given which describe the propagation effects under a variety of conditions. Present estimates of the influence of the ionized shock layer on propagation are deficient because of the limited knowledge concerning several of the basic gas parameters for air, as well as the inexistence of a proven method for determining the flow field about a re-entry vehicle. A program directed toward obtaining the needed information, through in-flight and laboratory experiments, is outlined.