I'm stuck with this integral equation :

$\displaystyle

\frac{jwI}{4\pi} ln(\frac{(d+x)^2+a^2}{(d-x)^2+a^2}) =\int_0^{\sqrt{\frac{\omega \sigma}{2}}}A(k) \sin \left(x \sqrt{-k^2+\frac{\omega^2\sigma^2}{4k^2}}\right)dk$

If anyone has any idea I'd be glad to hear.