Transmission coefficient estimation based on antenna voltage standing wave ratio under plasma sheath

Abstract

Radio blackout has confused the aerospace industry for decades. The highly attenuated caused by the plasma sheath is the main cause of radio blackout. The transmission coefficient depends on the relationship between plasma density, collision frequency and radio wave frequency. Meanwhile, the reflection of waves and the mismatching of antenna impedance caused by plasma sheath lead to the change of antenna voltage standing wave ratio (VSWR). In this paper, we analysis the relationship between the VSWR and the Transmission Coefficient. The variation of GPS antenna's VSWR with plasma sheath is simulated, the results demonstrate that VSWR is largely influenced with the electron density and the collision frequency. In addition, there is a strong correlation between VSWR, return loss and transmission loss. The correlation coefficient between the VSWR and wave transmission loss could be as high as -0.983. This relationship can support the idea that Transmission Coefficient can be predicted by detecting the variation of VSWR without requiring an additional feedback channel.