425 
p(x,y) = s e 
+ S 2 e ^cos(4r-x) 
Now, the surface is determined by: 
- small scale parameters: s, 1 respectively the height RMS and the correlation length 
- large scale parameters: S,L,P respectively the height RMS, the correlation length and the period 
Small scale 
Large scale 
- s : Standard deviation of the heights 
-1: Correlation length 
- S : Standard deviation of the heights 
- L : Correlation length 
- P: Periode 
Look Observation 
6 : Incidence angle 
<D: Azimutal angle 
d> = 0° : Perpendicular 
In this section, we will present the effect of the surface parameters (s,l) on the behaviour of the model. 
4.1 Isotropic surfaces: S=0 
The case presented here corresponds to a pea field. The height RMS (s) and the correlation length (1) arc 
measured with a variation ds and dl (s=s±ds l=l±dl). With different value of s and 1, we see that a 
decrease of the surface roughness involves an increase of the slope of radar cross section with incidence 
angle. 
Variation of the Height RMS (s) 
P2 (pea sowing Held) 
Configuration: CHH (5.35 GHz) 
Height RMS s = 0.8 cm 
Correlation lenght 1 = 4.2 cm 
ds = 0.1cm (measured standard deviation of s ) 
(ks = 0.9 Id = 4.7) 
Variation of the Corr elation Lenght flf 
P2 (pea sowing Held) 
Configuration: CHH (5.35 GHz) 
Height RMS s = 0.8 cm 
Correlation lenght 1 = 4.2 cm 
dl = 0.9 cm (measured standard deviation of 1 ) 
(ks = 0.9 Id = 4.7)