Effects of Pressure Variation on Polarization Properties of Obliquely Incident RF Waves in Re-Entry Plasma Sheath

Synthesizing the compressible turbulent flow theory and plasma electromagnetic (EM) theory together, a novel method connecting pressure variation and relative permittivity of re-entry plasma sheath is developed. Using this method and transmission line analogy, effects of pressure variation on polarization properties of obliquely incident EM waves at GPS frequency and Ka frequency is studied. Numerical results indicate that effects in different conditions are various. When electron density is lower than 10
¹⁸
m
^-3
, influences of pressure variation are obvious at GPS frequency, while Ka frequency is feeble. For GPS frequency, effects enlarge with the increase in incident angle, but reduce with the increase in collision frequency and electron density. Ka frequency has more advantages on mitigating the disturbances of pressure variations in this situation. While in the opposite situation, influences are more remarkable at Ka frequency. Considering that GPS wave rapidly attenuates in the sheath when electron density is higher than 10
¹⁸
m
^-3
and Ka wave does not, Ka frequency is an effective way to mitigate the blackout during the re-entry process after its shortcomings on polarization alteration have been carefully considered.