UHF RFID tag articles

Hi, i need some indications where i can find articles on RFID tag antenna operating in UHF band.
Please help me.

link to

http://www.impinj.com/page.cfm?CFID=...TOKEN=47482562

pl

Hi, thanks a lot Plasma.
I think that will be useful for me.
bye.

what is the exact freq u r working in ?