good geometry for 900mhz antenna of RFID

how are you, everyone?

i am trying to design a UHF antenna for RFID at 900MHz. bandwidth and impedance matching should be considered at the same time. i tried several geometries with different shapes and sizes, but i didn't found better one.

could anybody give me some advices on it? it is said in some publications, that an inductive stub can increase antenna impedance and loading bar can control antenna resistance. but what is inductive stub and how can i use it?

it is important and urgent.

thank you very much in advance.

You could try the Printed Dipoles presented in the attached documents:

Joshua David Griffin, "A Radio Assay for the Study of Radio Frequency Tag Antenna Performance", MS Thesis, Georgia Institute of Technology, 2005.

Using Electromagnetic Analysis for RFID Antenna Design, Sonnet Application Note: SAN-206A

thank you very much.

i am using sonnet for modified dipole design. i found i can't satisfied the s-parameter and impdance match coinstantaneously. i am confused.

why? does anybody meet the same problem?

i think it depands on the input impedence of your rfid tag, have you ever measure it?

thank you very much

it is useful !

If you don't enough point, you can download the files from the internet:

smartech.gatech.edu/handle/1853/7112

http://www.globalspec.com/Goto/GotoW...m=4&VID=121973

www.rdfwt.com

remove the space of rdf wt