UHF RFID Tag Resonant Frequency Measurement Method 1

[bendo]

Hi All,

Could anyone share how to measure the UHF tag resonant frequency?
*There is no direct access to the tag antenna, and the tag is covered by epoxy.

 

[Higgler]

do you know that it has a resonant frequency? i.e. some narrow band wonderfully efficient operating frequency? Or is it just like most small antennas, slightly efficient, not too resonant, but good enough to work?

what frequency do you expect?
do you have the specs on it?

kch

 

[zappedagain]

I like dip meters for this:

http://en.wikipedia.org/wiki/Grid_dip_oscillator

All depends upon your frequency though...

John D

 

[VEBill]

...and Q.

 

[bendo]

Hi Friends,

The UHF tag mentioned here actually work in the frequency range between 860MHz and 960MHz. And the tag is passive type, no battery inside.

We source the RFID chip (die form) from IC vendor, such as NXP. And we make dipole antenna connected to the RFID chip. The size of antenna normally is within 120mm x 50mm.

The impedance of RFID IC, for example, is 22-j195 ohm in 910MHz. So we make the antenna with the impedance of 22+j195. The problem is that after we put the IC+antenna inside the package (tag), we want to measure the tag resonant frequency in order to make sure the tag's bandwidth still covers 860MHz ~ 960MHz.

Attached is the brief introduction of the RFID Chip.

Thanks for your inputs!