RFID tag measurements

[itzikhaim]

rfid tag measurement

Hello to all!!

What is the best method for measuring RFID passive tags for UHF?
The tags don't include the chips.

How should I measure a back-scattering from an RFID tag (without the chip)?

The measurements should be in tne physical layer. (EM wave scattering)





I.H

 

[GVVIN]

rfid tag backscatter signal measurement

Hi


The Micro chip impedance is not 50 Ohms right, So the antenna is matched to some R +JX ohms.

for measurement you can use a RF probe (Wafer probe) and connect to network analyser and verify the impedance at the chip position (without chip). It should be the conjugate of the chip input impedance.

You cannot measure backscatter without the Chip.

Me too working on similar lines.. Have you done simulation of the same ??

regards
GV

 

[itzikhaim]

rfid measurement liquid

Hi GV!

Yes I did some simualtions with the aid of the CST application note (attached)

Can you send me some information/application note for matching the tag with wafer?
How you can make this measurement if the RFID tag has balanced input terminal?
(The Alien tag for example).

What about attaching a led to its terminal and by radiating on it, it will be "turned on" so we can think that the tag is back scattering (after its matched)?

I read also an article for measuring the response of the tag using two antennas (horn type) what do you think about this setup?
Can we perfrom it, still, without the chip (but with the matching network)?

Thanks for reply,

IH

 

[GVVIN]

impinj monza fr4 antenna

Hi,

I was doing some simulation in CST for Tag antenna design for near field. (H fields). My chip impedance is 48-J148 ohms, As shown in the document you attached I am connecting a Port of 48 ohms and a Capacitor in series for the chip impedance for the simulation. for measurement I am monitoring surface current , E and H fields. Also I am using another antenna and measuring the coupling.

Still I don't think you will get a backscatter signal without the chip, The chip is an active device which helps in retransmission (backscatter) of signal from Tag to reader. Also the RF signal wont be able to drive an Led , even if you convert to Dc the current wont be sufficient to drive an LED , so using LED is not possible. see below link for back scatter
**broken link removed**

Hope you are working of UHF RFID tag, Are you looking for near field (application near metals &liquids)or far field?, matching You can do stripline type matching.
Find attached the monza chip datasheet. page numbers 12 to 15 explains the different configurations and the impedance for each case is given in page 15. If its a differential configuration , see fig 3-11 connection is made between the RF ports and ground is left free.

Regards
GV

 

[itzikhaim]

rfid tags for weight measurement

Hi GVVN !

As I understood from you, the RFID tag chip doen't contain any "matching network" (resistor and capicator) and you will need to match the chip to the RFID tag antenna.

You said:

My chip impedance is 48-J148 ohms, As shown in the document you attached I am connecting a Port of 48 ohms and a Capacitor in series for the chip impedance for the simulation

I don't think this solve the matching issue for the chip.
You'll need to match the chip to his RFID antenna. Hence you be needing to find to antenna complex impedance (R+jX) and to match it to the RFID chip impedance (48-j148).

I work with UHF tags for near field application.

Please advise me about microstrip/stripline matching.
How you actually demodulate the backscatter signal from the RFID tag (RFID -> reader link)?

IH

 

[GVVIN]

rfid tag antenna manufacturer measure distances

Hi,

Yes , The chip is a tranceiver by itself and its impedance is not 50 ohms ,it has some R + J ohms , we need to match antenna to this. Normally Lumped elements cannot be used in tags due to physical constrains and manufacturability

Yes port in series with capacitor wont solve matching. This is only for simulation of antenna, to compensate for non 50 ohms impedance of Tag chip. Matching we have to do.

For near field Loop antenna or a varient of that or loop together with dipole is normally used. Loop gives Good H field.
matching - Stub matching you have to do, you cant incorporate lumped elements Cap and Ind in normal Tags.

Regards
GV

 

[itzikhaim]

tag antenna impedance measurement

Hello again GV!

About the matching with non lumped/discrete elements, this could be done as a part of the antenna printed striplines. Is this correct?

Second, what about analyzing the backscattering signal from tag to reader?
Is it possible to implantat the antenna reader + its demodulation and encoding for the "tag to reader link" by yourself or we need the reader antenna?
Can you recommend me for some reader to UHF with the latest protocol.
Does "Monza tag" has readers antennas as well?

The tags (and reader as well) need to be in UHF bands, hence the HF tags (13.56MHz) which much suitable for near field application and less prone to metals and near objects reflections should not be taken into account.


About the ability to measure the backscattering of the RFID tag withoutr the chip,
by connecting horn antenna (having G=10 dBi @~920MHz, for example) to port 1 of VNA and the other port (2) to an RFID tag (alone with balun for balanced RFID tag), and see the coupling between them in various distance and etc.
This could test the functionality of the RFID tag and the response when "reading" takes place.
Of course the ability of the RFID tag to backscatter with the chip's information and with the "self excited" mechanism could not be perfrom without the chip.

What do you think?

Thanks,
IH

 

[GVVIN]

tag backscatter

Hi IH,
yes correct, We have to do with pattern (Striplines).

measuring back scatter . There are certain link equations by which we verify how much power will be received back theoretically.
yes some readers do give RSSI from Tag and we can use the same to measure Back scatter. Monza tag is from inpinj and they have readers too.
**broken link removed**
Ti Atmel and others too have RFID products, **broken link removed**
which geography you are in. In Japan We have many local manufacturers.

Yes That is a good idea , you can convert the tag antenna impedance to 50 ohms without chip and connect to a Network analyzer, connect a test antenna to other port and measure coupling. Again there will be some deviation from actual, because of matching , may be we need to use lumped elements to provide tag chip impedance.

Also I have seen in simulation , the tags frequency is affected by proximity of even similar other tags, In simulation I am measuring coupling between two tags(same under development ones) placed close to each other to analyse its performance,

thanks
GV

 

[itzikhaim]

rfid time measurement

Hi GV!

Tell me about the abilty to "program" the RFID tag.
Is it possible?
When fitting the RFID technology into practice how should the designer or/and system engineer should make the most out of the technology?

As an R&D engineer, I need to check this technlogy for an application. Can you recommend me and advise me for some issues I need to be involved in?

Your simulations are very interesting. Keep up with the good work.

Thanks,
IH

 

[GVVIN]

rfid tag impedance measurement

Hi,

For feasibility analysis,No need to develop Tag , You can buy (samples will do) readily available Tags (different variety are available) and reader and make real time measurements. Do some theoritical study before buying.

Using RFID for your application also depends on what all other options you have and advantages and disadvantages of all.

Tags are normally of 3 types passive (using back scatter), Semi active (which is capable of receiving input from other sensors) and Active (which has battery inside). So depending on your application range required , on what (metal liquid carton etc) the tag needs to be placed etc etc select one.

Tags can be programmed Using RFID read/write equipments. From PC you can input EPC code into tag, also some other info also like weight colour price etc. can be loaded into Tag.

Regards
GV

 

[itzikhaim]

uhf impinj fr4

Hi GV!

Tell me about the abilty to "program" the RFID tag.
Is it possible?
When fitting the RFID technology into practice how should the designer or/and system engineer should make the most out of the technology?

As an R&D engineer, I need to check this technlogy for an application. Can you recommend me and advise me for some issues I need to be involved in?

Your simulations are very interesting. Keep up with the good work.

Thanks,
IH

 

[GVVIN]

inpinj rfid distance

Tell me about the abilty to "program" the RFID tag.
Is it possible?

yes with an RFID read/write device and its software , you can program.

When fitting the RFID technology into practice how should the designer or/and system engineer should make the most out of the technology?



Using RFID for your application also depends on what all other options you have and advantages and disadvantages of all.
depending on your application range required , on what (metal liquid carton etc) the tag needs to be placed etc etc select .


As an R&D engineer, I need to check this technology for an application. Can you recommend me and advise me for some issues I need to be involved in?

issues
1. read range , tag spacing , interference, readability near liquids metals, security , cost , application requirements like database user interface ,manupulation of data , alarms required, reusability etc

Regards
GV
Regards
GV

 

[boy]

texas instruments rfid chip impedance

Please try this paper. The authors of this paper also do RCS measurememt

 

[zirtapoz]

rfid antenna impedance measurement

Hello to all!!

What is the best method for measuring RFID passive tags for UHF?
The tags don't include the chips.

How should I measure a back-scattering from an RFID tag (without the chip)?

The measurements should be in tne physical layer. (EM wave scattering)





I.H

Try to use Ansoft designer, and draw the antenna pattern. and put asic(ic) as load whatever impedance it has. And finally use plane wave excitation. U can see the results..

 

[itzikhaim]

hf rfid system micro-cap

Hello to all, again!

Can someone tell me what is the protocol of the given RFID tag (label) as shown in attached picture? (e.g. EPCglobal Class 1 Gen 2)

I know that its from Tyco and M/A-Com.
Does the same antenna (tag/label) might be manufactured by other vendor along with their chip?

Last, if I have some tags (as shown), is there a way for me to know what is the type of the class and the protocol this tag uses?

Thanks, in advanced

IH

picture link:

 

[GVVIN]

rfid tag antenna measurment

go to your link

 

[zy032]

rfid reading distance measurement

hi all
I have the same problem in my study..
i donot know how to measurement the tag antenna's impedance (without the chip)
cause i want to know if my simulation is right.
is anyone know about this or have similar situation?

thanks,
ZY.

 

[GVVIN]

rfid input signal simulation tag

Hi
Hope you have gone though Cst_application_note_rfid.pdf given on top of this thread by itzikhaim.

Regards
GV

 

[zirtapoz]

rfid tags sensor input

hi all
I have the same problem in my study..
i donot know how to measurement the tag antenna's impedance (without the chip)
cause i want to know if my simulation is right.
is anyone know about this or have similar situation?

thanks,
ZY.

As i said before try to download ansoft designer(SW, free) and draw your antenna, put excitaion. and simulate. its easy.

 

[zy032]

que es el back scaterring en rfid

As i said before try to download ansaoft designer(SW, free) and draw your antenna, put excitaion. and simulate. its easy.[/quote]

but is it just simulation?
i want to measure the antenna after fabrication.. how to do this?.

Added after 7 minutes:

thanks GV.
.. i want to propose a antenna impedance's measure solution.
in UHF band,it is too difficult to get a accurate result.

thanks again.
ZY.