Search

Terahertz communication is considered as a potential solution to alleviate the communication blackout. However, it is not clear how the shape parameters of the vehicle affect the propagation of terahertz communications in the plasma sheath. In this article, the influence of half-angle on the plasma flow and terahertz propagation characteristics around blunt cone vehicle was investigated using the numerical hypersonic hydrodynamic model and multilayer transmission model. The maximum electron number density in the plasma sheath near the antenna decreases with the decreasing half-angle. The thickness of the high-density section in the plasma sheath is almost unaffected by the half-angle. As a result, the terahertz wave attenuation decreases with the decreasing half-angle. The half-angle is reduced from 20° to 5°, and the attenuation of electromagnetic waves is reduced by about 25 dB. Therefore, reducing the half-angle of blunt cone vehicle can effectively reduce the attenuation of electromagnetic waves. Finally, the feasibility of lowering the half-angle to solve the blackout problem during the whole reentry process was discussed; the results show the operating frequency of terahertz wave that maintains normal communication when the half-angle is 1° is reduced by 0.1 THz compared with the half-angle of 9°. Based on the study, a new scheme combining the reduction of half-angle of blunt cone vehicle and terahertz communication was proposed in this article to mitigate the RF blackout. [ABSTRACT FROM AUTHOR]

A self‐consistent calculation model combining flow field and electromagnetic wave propagation is presented. The hypersonic flow field around the RAMC‐II vehicle at different reentry heights is numerically solved using a computational fluid dynamics technique with a two‐dimensional model, and then perform self‐consistent calculations in conjunction with electromagnetic wave propagation models. The dependence of wave frequency, polarization mode, incident angle, and plasma collision frequency on the wave propagation is presented. Electromagnetic wave propagation characteristics have been investigated experimentally with shock tube, and the experimental results are consistent with the simulation results. Conclusions in this article can be the foundation to study the interactions between the electromagnetic wave and the realistic reentry plasma sheath. [ABSTRACT FROM AUTHOR]