Abstract: Low-frequency （LF） electromagnetic （EM） waves exhibit stronger transmission behavior under a plasma sheath， which has a positive impact on mitigating radio blackout. Previous work has established attenuation models for LF EM waves under the steady-state plasma sheath，but neglected the time-varying properties of the plasma， lacking an in-depth understanding of the channel characteristics. Therefore， this study focuses on the channel characteristics of dynamic plasma sheath on LF EM waves. The channel stochastic model of the dynamic plasma is established at LF EM wave bands， where the channel response of the dynamic plasma is merged with the colored-Gaussian time-varying electron density model. The first-order statistical properties of the dynamic plasma channel are obtained. The probability density function （PDF） of envelope P_r（r） is a power-Gaussian function， the PDF of the phase shift P_φ（φ） is a tangent-Gaussian function， and the power spectral density （PSD） function S_Hi（ω） is a colored noise function. To validate the effectiveness of the proposed channel statistical model， the muti-state numerical simulations are conducted， and the simulation results are in good agreement with the theoretical results. The electron density is 10¹⁸-10¹⁹/m³， the collision frequency is 1.5 GHz， and the frequency of LF EM waves is 1.30 MHz. When the electron density increases from 10¹⁸/m³ to 10¹⁹/m³， the degrees of random fluctuation on envelope and phase shift increase. The mean of P_r（r） increases from 1.33 to 34.04， and the standard deviation of P_r（r） increases from 0.13 to 14.34； the mean  of P_φ（φ） increases from 0.58 to 5.81， and the standard deviation of P_φ（φ） increases from 0.11 to 1.19； the PSDs are attenuated and broadened. The results reveal the channel characteristics of dynamic plasma at LF EM wave bands， which is significant for designing LF communication modulation algorithms and evaluating the performance of LF communication systems.

Key words:  , re-entry vehicles； plasma sheath； radio blackout； dynamic plasma channel； low-frequency electromagnetic waves