Modelling of antenna radiation pattern of a re-entry vehicle in presence of plasma

Upon re-entry into the Earth\´s atmosphere, space vehicles become shrouded in a plasma that affects all communications of spacecraft with ground and satellites. The flight of the Atmospheric Re-entry Demonstrator (ARD) of the European Space Agency (ESA) has allowed the experimental characterization of the communication channel between the capsule and one of the NASA Tracking and Data Relay Satellites (TDRS), flying at geosynchronous orbit. The paper deals with the study of antenna radiation through plasma during re-entry of the ARD vehicle. Despite some approximations, the obtained results are remarkably close to measured link losses, and provide an explanation of why these losses are much less severe than the initially expected "blackout".