Prediction of In-Flight Radio Frequency Attenuation by a Rocket Plume

Abstract

During rocket flights, ionized exhaust plumes from solid rocket motors may interfere with radio frequency transmission under certain conditions. A computational fluid dynamics and finite difference time-domain method coupling approach was established for predicting interference and radio frequency attenuation levels during an actual rocket flight. The detailed plasma flowfield and radio frequency transmission characteristics were revealed in the calculations. The calculated far-field received levels were compared with the in-flight attenuation data at different look angles (angles between the vehicle axis and the line of sight of the antennas), and the calculated results showed good agreement with the flight data over a wide range of look angles. An adaptation of the model, based on the diffraction theory, proved appropriate both for rough estimation of attenuation and for conducting a preliminary analysis of signal/rocket plume interactions.