426 
Sigma 0 (dB) 
4.2 Non Lsotropic surface: S*0 (quasi-periodic surface) 
The case presented here corresponds to a com sowing field on which the row structure appears clearly. 
The effects of a variation of the small scale surface parameters (s,l) is shown in figure 4. The azimuthal 
dependence of the back scattering coefficient o° is shown. 
On figure 4, we can note that the cross section o° perpendicular to the row direction (phi=0°) is always 
greater than o° parallel to the row direction (phi=90°). This difference of cross section between the two 
view directions (phi=0° and 90°) increases when the surface is smooth (s=s-ds or l=l+dl). The 
backscattering coefficient o° parallel to the row direction (phi=90°) is more sensitive to a decrease of the 
soil roughness. 
Sigma° with mean value of (1) and Is) 
FIELD : Cl (Corn Sowing field) 
10 20 30 40 50 60 70 80 
Incident angle (deg) 
Variation of the Height RMS (si 
(s = 1.32 cm : Height RMS) 
(ds = 0.13 cm : Standard deviation of s) 
10 20 30 40 50 60 70 80 
Incident angle (deg) 
Variation of the cor relation length (1) 
( 1 = 4.53 cm : mean correlation length) 
(dl = 0.95 cm : Standard deviation of 1) 
10 20 30 40 50 60 70 80 
Incident angle (deg) 
figure 4