Modeling HF/VHF Radio Wave Propagation Through Artificial Plasma Clouds

Artificial plasma clouds created by releasing easily ionized metal vapors in the ionosphere demonstrate unique potential for enabling over-the-horizon radio wave propagation. Developing accurate radio wave propagation models is crucial for advancing practical applications of this technology, including over-the-horizon communication and detection. However, the temporal evolution of plasma clouds and their dynamic coupling with the ionosphere present significant modeling challenges that remain inadequately addressed. This study aims to establish a high-frequency (HF) and very-high-frequency (VHF) radio wave propagation model capable of characterizing over-the-horizon signal transmission characteristics through artificial plasma clouds. We investigate the multipath and Doppler effects of artificial plasma clouds using the ray tracing method, with explicit consideration of the coupling processes among plasma clouds, the ionosphere, and upper atmospheric winds. A parametric model of effective scattering radius is developed, establishing quantitative relationships with incident angle, frequency, and electron density distribution of plasma clouds. Building upon the geometrical theory of diffraction (GTD), we further propose a refined electromagnetic scattering model incorporating the effective scattering radius, Earth curvature, ionospheric absorption, geomagnetic field effects, and antenna polarization modes. The model’s accuracy is validated with observational data from the Metal Oxide Space Clouds (MOSC) and Air Force Cambridge Research Laboratories (AFCRL) experiments.