This module computes the backscattering coefficient,
σ
0, 
for a given random rough surface, using the I
2EM model.
Various parameters of the rough surface can be specified, such as the
dielectric constant 
ϵ = 
ϵ' -j 
ϵ'',
the type of correlation function, and the parameters of the
correlation function.
The model is constrained to realistic surfaces with (rms height /
correlation length) ≤ 0.25. 
ks is also constrained to be less than 1.