Impact of Reentry Speed on the Transmission of Obliquely Incident THz Waves in Realistic Plasma Sheaths

Nowadays, the terahertz (THz) communication is believed to be a potential solution to the communication blackout for reentry vehicles. In this paper, a numerical hypersonic fluid model was introduced to obtain the realistic plasma sheaths. The onboard antenna which is installed on the wall was assumed to be conformal. The transmission of obliquely incident THz waves in the plasma sheaths was analyzed. According to this paper, the power transmission coefficient decreases with the increase of reentry speed since both the electron density and the electron collision frequency near the onboard antenna increase with the reentry speed. In addition, the relation between the wave transmission and the reentry speed is revealed. The power transmission coefficient decreases with the increase of incident angle, because the conformal antenna cannot receive the field component which is perpendicular to the wall. Two supplemental schemes to enhance the transmission rate for THz signals were discussed based on this paper.