# SATCOM Earth Station Arrays Anti-Jamming Based on MVDR Algorithm
## 4 Simulation Analysis
### Jamming Suppression Effect under Different Parameters  
To verify the universality of the proposed algorithms for jamming suppression in satellite communication earth station antenna arrays, three simulation experiments are conducted with four reflector antennas, a spacing of d = c/(2 \(\times\) f) \(\times\) 42 = 0.504 m, a noise power of \(-\)131.28 dBW, an jamming power flux density of \(-\)80 dBW/m\({}^{2}\), and varying jamming angles, snapshot sizes, and signal power flux densities. The results are the average of 200 Monte Carlo simulations.  
Experiment 1: Different Snapshots. To investigate the effect of snapshots on the jamming suppression performance of the MVDR algorithm, 10 snapshots ranging from 100 to 1000 are set with an interval of 100. In addition, the jamming direction is \(\theta_{1}=10^{\circ}\), and the signal power flux density at the reflector antenna is \(-\)110 dBW/m\({}^{2}\).  
From Figure 5, it can be seen that as the snapshots increases, the depth of null in the jamming direction using the MVDR algorithm with diagonal loading also increases, but the increase rate gradually slows down. The output SINR of the array also increases gradually, but the increase rate slows down after reaching a certain snapshot. Therefore, to achieve ideal jamming suppression performance while keeping the computational complexity reasonable, an appropriate snapshot needs to be selected. In addition, it can be seen that the output SINR of the algorithm proposed in this article is higher than that of the algorithm based on the sampling matrix inversion method at the same snapshots.  
Figure 4: Proposed antenna gain of earth station (\(D\) = 0.5 m).  
Figure 3: MVDR pattern of antenna array.  
Experiment 2: Different Signal PFD. To investigate the effect of signal power flux density at the reflector antenna on the jamming suppression performance of the MVDR algorithm, seven sets of data with signal PFD ranging from \(-110\) dBW/m\({}^{2}\) to \(-80\) dBW/m\({}^{2}\) in increments of 5 dB are set. In addition, the jamming direction is \(\theta_{1}=10^{\circ}\), and the number of snapshots is 512.  
From Figures 6 and 7, it can be seen that as the signal PFD at the reflector antenna increases, the depth of null in the jamming direction gradually decreases. Within the range of experimental data, the output SINR of the array using the MVDR algorithm with diagonal loading is the highest, followed by the array using the CBF algorithm, and the single antenna has the lowest output SINR. The output SINR of the MVDR algorithm with diagonal loading gradually slows down as the input SNR increases, while the output SINR of the CBF algorithm and the single antenna increases linearly with the input SNR. This indicates that the jamming suppression effect of the MVDR algorithm in satellite communication earth station antenna arrays deteriorates as the input SNR increases. This is because the algorithm uses the sample covariance matrix to replace the jamming plus noise covariance matrix, and high SNR leads to relatively small jamming plus noise power, resulting in a deterioration of jamming suppression effect.  
Figure 5: Output SINR and depth of null versus the number of snapshots.  
Figure 6: Depth of null versus PFD.