Radius

Well, yesterday I wrote a mail in spanish but I didn't get any answer so 
now I put it in english.
I been working with a big group of people, and we have an extensive 
wireless network. The fact is that we've detected some introuders in 
this network and they are doing some damage in our servers.
Well I've figured out that with Radius Server we can make a more secure 
wilan. I don't trust in the other security sistems.
My question is: the AP should work with some special protocol to 
comunicate with de Radius Server? and if it is so, work the client radio 
with some protocol to authenticate with Radius Server or is this done by 
the AP?
thanks a lot
                                     Jorge Garay