## 6 Results of Antenna Deployed on Satellite  
Following the validation of the QM antenna model through radiofrequency measurements, it is placed on a mockup (RF dummy) that replicates the actual Leader-S platform, including solar panels, a UHF antenna, and a magnetometer (see Figure 15a). In this new setup, the antenna is measured again in the anechoic chamber at INTA facilities, with the results of these measurements then being compared with those of the isolated antenna in order to assess how polarization and gain are affected by its deployment. The S-parameters of the antenna exhibit slight variations when mounted on the RF dummy, particularly on one of the ports, primarily due to the proximity of the S-band antenna to the UHF antenna (four monopoles). However, this variation is minimal and does not compromise the requirements, as it remains below \(-15\) dB within the band. The gain pattern of the mounted antenna (see Figure 16) exhibits a slight narrowing compared to the isolated case while maintaining the peak gain value without incurring additional losses. With regard to the cross-polarization pattern, a slight deterioration is observed in the angular region closest to the UHF antenna. However, this does not have a significant impact on the final requirements, as the system employs dual-polarization operation to select the optimal received pattern from both polarizations. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Ref** & **Frequency** & **Polarization** & **AR Bandwidth** & **Gain (dBi)** & **Size (mm)** & **Weight (gg)** & **Space** & **Position Type** \\ \hline
[5] & S-Band (2.4) & CP & 2 & 7.3 & \(96\times 96\times 7\) & – & no & Multiple \\ \hline
[9] & S-Band (2.4) & CP & 4 & 2.3 & \(100\times 100\times 11\) & 120 & yes & Dual feed \\ \hline
[10] & S-Band (2.43) & CP & 3.5 & 4.89 & \(68.5\times 59.4\times 6\) & 75 & no & Single feed \\ \hline
[21] & S-Band (2.43) & CP & 6 & 8.07 & \(42\times 55\times 4.8\) & 145 & no & Dual feed \\ \hline
[22] & S-Band (2.2) & CP & 16 & 5.9 & \(78\times 75\times 10\) & 97 & no & Dual feed \\ \hline
[35] & S-Band (2.4) & CP & 2.45 & 4.8 & \(19\times 20\times 7.2\) & – & no & Dual feed \\ \hline Designed Antenna & S-Band (2.2) & CP & 8 & 7.2 & \(80\times 80\times 6.5\) & 30 & yes & Single feed \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of the parameters of the referenced antennas. The mounted antenna on the RF dummy exhibits gain values with no losses in comparison to the isolated antenna. Indeed, at lower frequencies, the maximum gain through port P1 is 7 dBi, while through port P2, it reaches 7.6 dBi. At higher frequencies, the gain through port P1 is 7.1 dBi, and through port P2, it is 7.2 dBi. This variation in the maximum gain values of the S-band antenna is attributable to its position relative to the UHF antenna, which comprises four monopoles positioned asymmetrically with respect to P1 and P2. Consequently, the gain is influenced in a slightly different manner on each port by that UHF antenna. Given that the antenna is based on a multi-layer stacked patch structure, the gain achieved once the antenna is mounted on the satellite and measured is excellent. Furthermore, the gain remains highly stable, with a rate of decline of only 0.14 dB per degree. Figure 16: Gain measurement of S—band antenna isolated vs. placed on RF dummy; (a) f = 2.03 GHz—Port 1; (b) f = 2.03 GHz—Port 2; (c) f = 2.205 GHz—Port 1; (d) f = 2.205 GHz—Port 2. Figure 15: (a) QM S Band antenna on RF dummy (measurements set—up); (b) \(|\)S11\(|\) and \(|\)S22\(|\) measurements of isolated QM antenna vs. placed on RF dummy. Although the axial ratio (Figures 17 and 18) is the parameter most affected when the antenna is mounted on the satellite, it shows minimal distortion within the area of interest (boresight) at all frequencies measured, especially on port 2. However, the axial ratio at Port 1 and f = 2.03 GHz is more affected due to its proximity to the monopoles of the UHF antenna, which reduces the angular range to \(-20/+40\) degrees.