Any reference about antenna measurement?

I am wondering how the antenna measurement in an anechonic chamber works? I know we need the standard horn and do some comparison for the AUT, but I am still not sure about how it works.... Any reference and article will be appreciated.

http://www.yorkemc.co.uk/info/techni...hamber-cne.pdf
http://wireless.ictp.trieste.it/scho...ous_presen.pdf

hello,

this is an introductory text to antenna measurements. it is from orbit, a manufacturer of anechoic chamber positioners.

regards