## 5 Data Processing and Experimental Results: SAR Mode
### First Results  
As shown in Figure 2 (green and blue tracks), all the sites (TS1, TS2, TS3 and TS4) were inspected with the SAR modes. In particular, over the TS1 and TS4 sites, a number of repeat pass interferometric acquisitions were carried out. Accordingly, different full polarimetric as well as interferometric datasets were collected. Among the overall acquired dataset, we report in the following some representative results relevant to the SAR-Low mode data acquired over the TS2 and TS4 sites. To show the potentialities of this full-polarimetric SAR system, we consider one radar acquisition carried out over the TS2 site. Application of the processing chain depicted in Figure 9 has led to the generation of four focused Single Look Complex (SLC) data, one for each polarimetric channel. Table 2 reports main data processing parameters. Figure 10 shows, in radar grid (that is, range-azimuth), the amplitude of the corresponding Multi Look Complex (MLC) data relevant to the VV channel. In the right vertical axis of the figure it is specified the (mean) look-angle corresponding to the range coordinate reported in the left vertical axis. The observed scene has an extension of about 9 Km in azimuth and 2.5 Km in range. Figure 11 shows the SAR image of Figure 10 in geographic grid and superimposed to a Google Earth orthophoto. The green line represents the flight track projected on the ground. As can be seen in the orthophoto reported in the left panel, the area exhibits an overall flat topography and it can substantially be considered as a rough bare soil. The amplitude and phase of the correlation coefficients between the polarimetric channels are depicted in Figure 12. In particular, see Figure 12a, the amplitude of the co-polar (HH-VV) correlation coefficient assumes quite high values (greater than 0.6) up to a range distance of about 3 Km, corresponding to a mean look-angle of about 70\({}^{\circ}\), while the average phase difference between these channels is very small (approximately \(\pi\)/8), see Figure 12b. From Figure 12a it can be also observed that the amplitude of the average normalized cross-products between the co-polar (HH and VV) and cross-polar (HV and VH) channels is very low, as it happens when the observed targets exhibit reflection symmetry [78]. These results are thus compatible with the scattering behavior expected in the presence of rough bare soil. The presence of rough bare soil, whose dominant scattering mechanism is the presence of rough bare soil, is not a significant effect. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline Azimuth spacing (SLC) & 0.64 m & Range spacing (SLC) & 1.5 m \\ Azimuth resolution (SLC) & 1 m & Range resolution (SLC) & 5 m \\ Azimuth spacing (MLC) & 0.64 m & Range spacing (MLC) & 1.5 m \\ Azimuth resolution (MLC) & 7.5 m & Range resolution (MLC) & 12.8 m \\ \hline \hline \end{tabular}
\end{table} 
Table 2: SAR data processing parameters relevant to the results collected in Figures 10–13. Figure 11: Left panel: Google Earth orophoto including the observed area. Right panel: As Figure 10, but represented in geographic grid and superimposed to the Google Earth orthophoto of the left panel. Figure 10: SAR results, relevant to one flight track on TS2. VV channel. SAR-Low mode. Amplitude of the SAR MLC, in radar grid. Mean flight velocity: 40 m/sec. Mean flight altitude: 1664 m. Mean terrain height: 815 m.  
is the surface scattering contribution [78; 79], is confirmed also by the results of the obtained Pauli decomposition [78], which is depicted in Figure 13, where the class of the odd-bounce scattering events (the greenish pixels) is strongly dominant up to distances of about 3 Km. Beyond this range, the transmitted waves impinge the surface at grazing incidence (look angles greater than 70\({}^{\circ}\)), thus leading to a non-negligible diffuse scattering contribution (the reddish pixels in Figure 13), and to HH and VV returns which are almost completely uncorrelated, see Figure 12a.