Analysis on the Propagation Characteristics of Terahertz Signals in Blunt-Coned and Sharp-Coned Vehicle in Different Sizes

In the recent decade, Terahertz (THz) communication has been recognized as one of the possible paths to solve the communication blackout for reentry vehicles. Previous studies have mainly focused on the plasma structure and Terahertz signal propagation mechanisms of vehicle of the same model. However, actual vehicle comes in various sizes, necessitating further research into the relationship between different-sized vehicle and Terahertz signal transmission characteristics. This study takes typical RAM-C blunt-coned and pointed-coned vehicles as objects to analyze the impact of vehicle size changes on plasma sheath parameters. The propagation characteristics of Terahertz signals in plasma sheaths of different sizes were studied using the scattering matrix method (SMM) method. The analysis conclusion indicates that as the size of blunt-coned and sharp-coned vehicles increases, the thickness of the plasma sheath layer also increases, resulting in more severe attenuation of Terahertz signals. Increasing the size of the vehicle enhances electron collision frequency, while the fluctuation in maximum electron density increases with the size of blunt-coned vehicle and decreases with the size of sharp-coned vehicle. In the Terahertz signal transmission characteristics, blunt-coned vehicles are mainly affected by signal absorption, while sharp-coned cone vehicles are affected by both reflection and absorption. Reducing the size of the vehicle and the thickness of the plasma sheath layer can mitigate Terahertz signal attenuation.