# SATCOM Earth Station Arrays Anti-Jamming Based on MVDR Algorithm
## 4 Simulation Analysis
### Jamming Suppression Performance in Actual Satellite Communication
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Downlink signal frequency & 12.5 GHz \\ Satellite fixed-point longitude & 110.5\({}^{\circ}\) E \\ Earth station antenna diameter & 0.5 m \\ Earth station longitude & 108.5\({}^{\circ}\) E \\ Earth station latitude & 34\({}^{\circ}\) N \\ EIRP of the satellite & 52 dBW \\ Atmospheric absorption loss & 0.5 dB \\ Feeder loss & 0.5 dB \\ Altitude of the jamming source & 5 km \\ Equivalent noise temperature of the earth station & 150 K \\ Noise bandwidth & 36 MHz \\ SNR threshold of the earth station & 7 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The parameters of satellite communication system. the array based on the CBF algorithm, and the array based on the MVDR algorithm with diagonal loading can all communicate normally. When \(-\)7.18 dBW \(<\) EIRP of the jamming source \(<\) 5.37 dBW, the single antenna cannot communicate normally, and the array based on the CBF algorithm and the array based on the MVDR algorithm with diagonal loading can communicate normally. When the EIRP of the jamming source is greater than 5.37 dBW, only the array based on the MVDR algorithm with diagonal loading can communicate normally. In experiment 4, assuming that the EIRP of the jamming source is \(-\)5 dBW, the incident angle of the jamming source is set from 5\({}^{\circ}\) to 80\({}^{\circ}\) with an interval of 0.1\({}^{\circ}\). From Figure 10, it can be seen that when the incident angle of the jamming source is 28.1\({}^{\circ}\) (the distance between the jamming source and the earth station antenna is 5.67 km), the output SINR of the single antenna is about 7.01 dB, and the output SINR of the earth station array based on the CBF algorithm and the array based on the MVDR algorithm with diagonal loading is greater than 7.01 dB, exceeding the SNR threshold of the earth station. When the incident angle of the jamming source is less than 28.1\({}^{\circ}\), the output SINR of the earth station array based on the MVDR algorithm with diagonal loading is greater than 7 dB at most angles. Therefore, when the incident angle of the jamming source is \(\leq\)\(-\)28.1\({}^{\circ}\) or \(\geq\)28.1\({}^{\circ}\), the single antenna, the array based on the CBF algorithm, and the array based on the MVDR algorithm with diagonal loading can communicate normally. When \(-\)28.1\({}^{\circ}\) \(<\) incident angle of the jamming source \(<\) 28.1\({}^{\circ}\), the single antenna cannot communicate normally, the earth station array based on the CBF algorithm can only communicate at fewer angles than the array based on the MVDR algorithm with diagonal loading. Based on statistics within the range of angles in this experiment, assuming that the incident angle of the jamming source is uniformly distributed, the probability that the earth station array based on the MVDR algorithm with diagonal loading can communicate normally is over 95%. In addition, it was found by calculation that there are angles in Figure 10 where the jamming suppression performance of the CBF algorithm and the MVDR algorithm with diagonal loading is poor. This is because the signal angle in this experiment is 0\({}^{\circ}\), resulting in \(a(\theta_{0})\) = [1,1,1,1]T, and the above angle \(a(\theta_{i})\) is very close to \(a(\theta_{0})\). Moreover, the antenna elements in this experiment are four completely identical planar antennas, so \(Q(\theta_{i})a(\theta_{i})\) = \(Q(\theta_{i})a(\theta_{i})\), and the directional vectors of the satellite signal and the jamming signal can be, respectively, represented as \(Q(\theta_{0})a(\theta_{0})\) and \(Q(\theta_{i})a(\theta_{i})\). Then, \(w^{\rm H}Q(\theta_{0})a(\theta_{0})/(w^{\rm H}Q(\theta_{i})a(\theta_{i}))\)\(\approx\)\(Q(\theta_{0})/Q(\theta_{i})\), so the output SINR of the array is approximately equal to that of the single antenna.