transmitter RFID tag instead of transponder

Thread Starter

ramy_a

Joined Feb 3, 2020
4
Hi guys,
As I know RFID tags are transponder which means they need to receive a message through the antenna and after demodulating an answer will be generated. However, I wonder if we can bypass the Demodulator and turn the tag into a transmitter. please guide me if you have any solution for that?
Thanks
 

Reloadron

Joined Jan 15, 2015
5,118
Thank you for your answer. I am thinking about battery assisted RFID tags. can I turn them into an independent 13.56 MHz transmitter?
I don't see why a battery couldn't be included but it would sort of defeat some of the RFID technology.
"In an effort to lower Tag cost and address applications of high quantity Tags usage, the 13.56 MHz solution was born. At this frequency, a Tag’s coil need not be made of hard copper wrappings. The coil can actually be a printed ink on a paper like substrate which than has an eeprom added to it. During the mid to late 1990’s, 13.56 MHz was the vogue technology that many experts saw as a path to addressing high quantity applications necessitating low Tag costs".

The above quote taken from here. Among the goals of the 13.56 MHz technology was the antenna could be printed not requiring copper antenna windings and as seen getting cost down. Adding a battery would increase size, weight and cost. Can it be done? I don't see whay not as long as added bulk and cost are not important or a consideration.

Ron
 

AlbertHall

Joined Jun 4, 2014
9,281
But what does adding a battery get you?
It's still only going to do anything when it receives a signal and it doesn't rransmit, it only modifies the transmitted signal.
From wiki:
Tags operating on LF and HF bands are, in terms of radio wavelength, very close to the reader antenna because they are only a small percentage of a wavelength away. In this near field region, the tag is closely coupled electrically with the transmitter in the reader. The tag can modulate the field produced by the reader by changing the electrical loading the tag represents. By switching between lower and higher relative loads, the tag produces a change that the reader can detect.
https://en.wikipedia.org/wiki/Radio-frequency_identification#Signaling
 

MisterBill2

Joined Jan 23, 2018
5,188
I am wondering about the purpose of the whole effort. Nothing but RFID tags uses the frequency, and having a tag start transmitting could certainly confuse a system designed to stop theft. So will the TS please let us know what other use such a transmitter could have.
 

Thread Starter

ramy_a

Joined Feb 3, 2020
4
I don't see why a battery couldn't be included but it would sort of defeat some of the RFID technology.
"In an effort to lower Tag cost and address applications of high quantity Tags usage, the 13.56 MHz solution was born. At this frequency, a Tag’s coil need not be made of hard copper wrappings. The coil can actually be a printed ink on a paper like substrate which than has an eeprom added to it. During the mid to late 1990’s, 13.56 MHz was the vogue technology that many experts saw as a path to addressing high quantity applications necessitating low Tag costs".

The above quote taken from here. Among the goals of the 13.56 MHz technology was the antenna could be printed not requiring copper antenna windings and as seen getting cost down. Adding a battery would increase size, weight and cost. Can it be done? I don't see whay not as long as added bulk and cost are not important or a consideration.

Ron
Thanks. Actually, active and battery-assisted RFID tags already exist. They are more stable and have a better read range. however, they still need a message from a reader to produce the answer. In my case, I am more interested in 13.56 MHz as it became popular. to my knowledge, every RFID tag has some parts such as Demodulator, Modulator, Rectifier, Processor, antenna, etc. I try to bypass the Demodulator as I don't need it to answer so I am more in need of a 13.56 MHz transmitter.

But what does adding a battery get you?
It's still only going to do anything when it receives a signal and it doesn't rransmit, it only modifies the transmitted signal.
From wiki:
Tags operating on LF and HF bands are, in terms of radio wavelength, very close to the reader antenna because they are only a small percentage of a wavelength away. In this near field region, the tag is closely coupled electrically with the transmitter in the reader. The tag can modulate the field produced by the reader by changing the electrical loading the tag represents. By switching between lower and higher relative loads, the tag produces a change that the reader can detect.
https://en.wikipedia.org/wiki/Radio-frequency_identification#Signaling
I didn't add the battery. The tag is already battery-assisted. I want it just to be a transmitter instead of a transponder. so I thought it may be possible to bypass the demodulator.
 

Thread Starter

ramy_a

Joined Feb 3, 2020
4
I am wondering about the purpose of the whole effort. Nothing but RFID tags uses the frequency, and having a tag start transmitting could certainly confuse a system designed to stop theft. So will the TS please let us know what other use such a transmitter could have.
definitely, I just want to use the 13.56MHz. but it won't confuse the anti-thief system as most of the smartphones now have such technology embedded.
 

AlbertHall

Joined Jun 4, 2014
9,281
As I understand it they DO NOT TRANSMIT ever. They change the loading on the antenna which the external transmitter detects. See the wiki link in #5.
 
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