## 4 Experimental Verification and Analysis
\[P_{\min}=-50+G_{t}-L_{a}-L_{b}-L_{c}-L_{d} \tag{45}\]  
where \(G_{t}\) represents the antenna's transmission power, and here \(G_{t}=11\) dB; \(L_{a}\) represents polarization loss, and here \(L_{a}=0\); \(L_{b}\) represents cable loss; \(L_{c}\) represents the attenuation value set by the attenuator; \(L_{d}\) represents spatial attenuation, and its calculation formula is:  
\[L_{d}=32.44+20\lg f(\mathrm{MHz})+20\lg D(\mathrm{km}) \tag{46}\]  
where \(f\) represents the frequency of the working signal, measured in MHz, and \(D\) represents the distance from the center of the spherical cap array to the anechoic chamber's simulated source, measured in km. From the experimental results in Table 1, it can be observed that the beamforming algorithm used in this scheme achieves a measured beamforming sensitivity of less than \(-133\) dBm for each illumination angle. Compared with other beamforming methods, the MVDR method is used for DBF with the array antenna. Due to the sensitivity of the MVDR beamformer to the mismatch between theoretical and actual direction vectors, the beamforming sensitivity at all tested angles only reached about \(-125\) dBm. By using a beamforming method based on prior information and spatial domain search, the sensitivity was improved by approximately \(8\) dB. Before introducing the spatial domain search-based beamforming method, the beamforming sensitivity at all test angles using only the prior information-based method was greater than \(-129\) dBm. After its introduction, the sensitivity improved by more than \(4\) dB. (3) G/T Value Testing  
The G/T value refers to the ratio of gain to noise temperature, which is used to measure the receiving capability of an antenna under noise temperature conditions. To verify  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**R94 Frequency Point**} & \multicolumn{3}{c}{**R42 Frequency Point**} & \multicolumn{3}{c}{**L42 Frequency Point**} \\ \cline{2-11}  & \multicolumn{3}{c}{**Symbol Rate: 40 kbps**} & \multicolumn{3}{c}{**Symbol Rate: 40 kbps**} & \multicolumn{3}{c}{**Symbol Rate: 40 kbps**} \\ \cline{2-11}
**Illumination Angle** & \multicolumn{3}{c}{**Cable Loss Loss \(L_{b}\): 17.59 dB**} & \multicolumn{3}{c}{**Cable Loss \(L_{b}\): 17.07 dB**} & \multicolumn{3}{c}{**Cable Loss \(L_{b}\): 17.46 dB**} \\
**Azimuth, Unit :** **3** & \multicolumn{3}{c}{**Spatial Attenuation \(L_{d}\): 50.68 dB**} & \multicolumn{3}{c}{**Spatial Attenuation \(L_{d}\): 50.75 dB**} & \multicolumn{3}{c}{**Spatial Attenuation \(L_{c}\): 50.68 dB**} \\ \cline{2-11}  & \multicolumn{3}{c}{**D. 364 nm**} & \multicolumn{3}{c}{**D. 367 nm**} & \multicolumn{3}{c}{**D. 364 nm**} & \multicolumn{3}{c}{**D. 364 nm**} \\ \cline{2-11}  & \multicolumn{3}{c}{**\(L_{c}\)**} & \multicolumn{3}{c}{**\(P_{\min}\)**} & \multicolumn{3}{c}{**CNR**} & \multicolumn{3}{c}{**\(L_{c}\)**} & \multicolumn{3}{c}{**\(P_{\min}\)**} & \multicolumn{3}{c}{**CNR**} & \multicolumn{3}{c}{**\(P_{0}\)**} \\ \cline{2-11}  & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} & \multicolumn{3}{c}{**(dB)**} \\ \hline \(10,0\) & \(26\) & \(-133.27\) & \(53.21\) & \(0\) & \(27\) & \(-133.82\) & \(53.82\) & \(0\) & \(27\) & \(-134.14\) & \(53.12\) & \(0\) \\ \hline \(10,90\) & \(26\) & \(-133.27\) & \(53.42\) & \(the beamforming effect of the receiving antenna array, G/T value tests were conducted at various angles for the antenna array. The testing was carried out through an equivalent sensitivity method: that is, by first measuring the sensitivity of the receiving terminal along the beam axis, and then using the equivalent conversion formula for G/T values to obtain the G/T value of the receiving terminal.