Effects of Reentry Plasma Sheath on Performances of Horn Antennas

Reentry plasma sheath has an important effect on radio communication between reentry vehicles and ground control. The commonly used antennas of reentry vehicles include spiral antenna, horn antenna, and slot antenna, etc. This paper studies the effects of plasma sheath on horn antennas during a typical reentry phase. The return loss and radiation characteristics of the horn antennas covered with plasma sheath are simulated based on the parameters of the RAM (Radio Attentuation Measurements) flight tests. The changes in antenna performances are analyzed in detail. The analytical start and the end of the reentry blackout process agree with the corresponding blackout process according to the NASA report.