Calculating Shieldi Effectiveness with Femm

[emiliano.menghi@xxxxxxxxx]

Hi,i use Femm to calculate the shielding effecctiveness (at 50 Hz) of 
various ferromagnetic and non-ferromangetic materials. But i've some 
problems.
My configuration is simple: a copper conductor with 1000 A and a 
cylindrical shield.
But Femm calculate error value for A vector.
I used some boundary condition (A=0 and unbounded condition) but the 
problem is present.
Infact when i calculate source impedence at distance of 20 mm (Ez/Hx)
the excact value is 140 but Femm tell me about 30.
Where is the problem?
Thank you and excuse me for my poor enghish.
By