RFID antenna problem

Now I have a antenna problem on RFID antenna; If I want to design 4 antennas printed on a 85*55 mm2 PCB board. Two antennas are operated at 915MHz, the other are design at 2.4GHz. How shall I do this design?

Shall I use loop antenna or PIFA ?

someone can give me some suggestions on this question.


Thanks in advance.

There are alot of disigns you can find in the net...
The choice is depend on appication of your tag, what kind of polarisation, pattern of radiation you need etc. In one case it is more rational to use a vibrator antenna, in other - patch antenna.
IMHO for 2.4MHz band the rectangular patch is the best choice.

PS What simulator do you use?
PPS This book may be usefull:
Compact and Broadband Microstrip Antennas - KIN-LU WONG
Planar Antennas For Wireless Application - KIN-LU WONG