Absorption and Scattering cross section

Dear Fellows,

Is there any of you who has experience with creating absorption and scatering cross section for dipole antenna?

So this is the story, there is gold dipole antenna on the glass.
I want to calculate enhancement of E field (I solved it) but I also want to calculate
scattering and absorption cross section.

I just know that I have to do some integration etc.

Do you have some simple model which I can use for basic learning?

Or maybe you have some suggestion which model to use for learnign from model galery?

Thank you very much in advanced.