Urgent help: RFID antenna design please?

please anyone help me to design antenna for RFID tags(passive). The antenna should be as small as possible at the frequency of 13.56MHz.Also it should possess read range as gar as possible. Please tell me the ways to design for the least geometry of the antenna. Also tell the details of the antenna type u propose.
Please do it for me & i will be greater for you .

Answer:
usually small antennas do not have very good distance.

the maker of the RFID chips will have a good design, they have balanced antenna size with good range, and that is not easy to do.(probably why you asked the question)

start somewhere like here to learn how to do it.
http://www.dxzone.com/catalog/antennas/t...

but you will usually see that is is easier to buy and then copy what the manufacturers have done.

at 13.56c.p.s. I would suggest using a ferrite core, just using the magnetic part of the EM wave can sometimes work really well and it is quite small when compared to other designs.

there are so many ways to do it,

it would help to answer your question if I knew the largest antenna you could tolerate, does it need to fit in a van or your pocket or way smaller than that ?
what distance are you looking for ?
a few inches, or a few hundred meters ?
I believe a printed loop may work, with a spiral design. I I did design and test one at 433 MHz. I was about 4" in diameter and had about 1.5 turns I think. For 13 MHz, print as many turns as practical. The diameter can be whatever you want but the smaller you go, the efficiency goes down. Then, put a capacitor across the "coil" that is printed so that it resonates. Do this by measuring the inductance of the loop and calculating.

I also made one at 180 KHz by winding 64 turns of wire in a 2" loop . I resonated it with a capacitor. I am not sure if I used a series or parallel arrangement.

emaiil me thru yahoo if you want

The answers post by the user, for information only, FunQA.com does not guarantee the right.



More Questions and Answers:
  • Will Sasrta Univ call for next councelling?they have called only till 4000..?
  • How do you correct air flow theair condition ducts?
  • In an engineering college do they look for class 12s marks during placements in various MNCs?
  • Are electronic engineers in high demand nowadays?
  • Is electronic&communication eng. and electronics &instrumentation eng.same?if not wat is the diference?
  • What electronics engineer study?how they work??
  • I have an object that is 13 1/8" tall. At what angle do I need to angle it so that it is 11" tall?
  • Where can I access the 7th Edition ITE Trip Generation Manual Online for Free?
  • What is the difference between a closed loop and an open loop circuit in hydraulics?