Application of Direct Simulation Monte Carlo Method to Computation of RF Signal Degradation During Hypersonic Flight
Date of Award
Master of Science (MS)
In order to further understand the hypersonic blackout problem, the first step is to investigate models to quantify signal degradation and begin implementing these models to representative plasma sheath and flow data. This research is the first attempt at implementing a model to predict RF signal degradation through the plasma sheath surrounding the hypersonic air vehicle. The investigation is performed using a Direct Simulation Monte Carlo (DSMC) based flow solver. The dsmcFoam solver in the OpenFoam library is used to simulate the flow around hypersonic bodies to obtain flow field properties, most importantly the electron number density profile, to aid in the calculations of signal degradation. The study of viability of RF communications from hypersonic, fixed-wing aircraft are paramount to the future of hypersonic military capabilities and even hypersonic travel. Predicting signal degradation for a transmission along a line of sight in real-time can eliminate radio blackout by guiding the gain models on the signal decoding side and allowing reconstruction of the transmission. Even without reconstruction, accurately predicting when signals will be unrecoverable can serve as an indicator for a hypersonic vehicle to send communications to a different ground station or satellite. The integration method employed to integrate over the output electron number density profile yields values for attenuation that drop below 100 decibels in the transmission window of 10 to 30 GHz. Outside of this transmission window, attenuation and phase shift are high indicating poor chance of viable communication. If signal degradation models can be verified and improved with the flight data in the future, these results suggest that vital radar and satellite communications are possible through the plasma sheath and can be decoded using accurately predicted degradation values.
Ramesh K. Agarwal
Dave Peters Swami Karunamoorthy