RFID Spiral Antenna requirement

Hello Guys, I have this problem...
I need to design a rectangular antenna for a RFID antenna but I don't know any other parameters I need to calculate.
I have obtained a CST 2010 software, tried to design the rectangular antenna but I do not know what next to do with it.
I am working on 13.56MHz frequency.

Please I really need your help.
Thanks in advance.

---------- Post added at 10:28 ---------- Previous post was at 10:23 ----------

Also, I need a guide on how to interpret the results obtained from the simulation.

Thanks in advance.

hi for this frequency usually used active antenna
pls read small antenna design by douglas miron

Thanks ferdows...
Please where can I get this material?

---------- Post added at 15:51 ---------- Previous post was at 15:47 ----------

Thanks, I have found it...
I will get back to you...

whats u mean ? i cant understand

I mean I have gotten the textbook. And it is really good.
And also, should I need any further guide, I will post it up.

Thanks ferdows, you've help to make my day...