Questions tagged [rfid]

Radio Frequency IDentification

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21 views

RFID Transponder transmission and reception working

I am reading about RFID systems and designs, and I stumbled upon this Digikey article. I am really confused with Figure 5 in that article. In the above IC diagram, I am really confused with pin 2, ...
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22 views

Options for passive long range sensors

What I'd want to do is to use cheap disposable temperature sensors and to read the temperature data wirelessly. The sensors would be set in a medium such as reinforced concrete. Right now I'm using ...
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17 views

Do active NTAG215 transducers exist?

Is there such a thing as an active NTAG215 transducer that can be used in place of a passive NFC card and programmed on-the-fly? I've got a project right now that uses NTAG215 NFC labels but since ...
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12 views

RC522 has other pins than shown in all the tutorials

I've bought an RFID RC522 module which I intend to use with my Raspberry Pi 3B+. I read the following tutorials and I noticed that their modules have other pins than the one I bought: https://www....
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1answer
14 views

Override value of RFID tag from external sensor

I have the following scenario, there is a RFID tag attached to a certain object which also have a light sensor on it (this is just for illustrative purposes, it could be another type of sensor), I ...
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1answer
32 views

Inconsistent performance of circularly polarized antenna

I have a circularly polarized patch antenna for an RFID reader, with a gain of 8dBi and bandwidth from 914MHz to 919MHz and an axial of 0.34dB. I have read that using a CP RFID patch antenna means ...
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26 views

Unable to read Gantner RFID wristband from my gym

I have an RFID wristband from my gym, of which I know they use the Gantner systems, so I assume it must be this (however I can't be sure, but it looks exactly like the black one on that website): ...
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1answer
42 views

Design coil for rfid chip

I broke an rfid coil which is soldered to a chip. I want to build the coil as it will save me the pain of replacing the chip as it's not something you can find easily. The coil itself was quite ...
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12 views

Question about RFID reader sensitivity

I have read that in RFID systems, the range is almost always dependent on the tags sensitivity to pick up the signal, not the readers. But this information is related to UHF RFID systems, and I would ...
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4answers
168 views

What is unit jω?

I have an equation, from which I'm calculating the induced voltage received by an RFID tag antenna. I know that \$ω\$ = angular velocity, but what is \$jω\$? And if \$jω\$ is related to angular ...
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24 views

RFID tag sensitivity

I have an RFID simulation that has an antenna, which generated power is 2 mT in a certain range. If an RFID tag has a sensitivity of -10 dBm, can I use that information to evaluate if the tag will ...
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1answer
33 views

NFC Loop Antenna placement

I'm trying to design a NFC loop antenna according to the following specification: http://www.ti.com/lit/an/sloa135a/sloa135a.pdf In the design the loops are placed on the top layer of the PCB, same ...
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2answers
37 views

Cheap RFID tracking to log entry and exit?

I am performing an experiment where I want to track entry and exit of insect from a small opening over time. My goal is that each insect will have a tag and each pass through will ping the reader to ...
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121 views

How to transmit a 125kHz signal?

I want to transmit a 125 kHz signal. The square wave signal is generated by the microcontroller (just transmitting no data and no receiving,) the transmitting and receiving antennas are tuned to ...
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20 views

How to find a threshold power to activate passive RFID tag?

Is there any minimum power which a low frequency RFID tag needs to power itself? I have yet not found this information from any datasheet of several RFID tags. I have a simulation, where I know how ...
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34 views

What is the minimum magnetic field required to power a passive low frequency RFID tag?

I am trying to solve the minimum magnetic field required to power a low frequency RFID tag. I found the right equation from the RFID-Handbook, but I have 2 parameters that I can't solve, these are: ...
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20 views

Find PCB Antenna impedance and matching circuit

I'm working on a project that uses NFC interface. I need to design two antennas: one for the RFID tag and another for the NFC initiator. I decided to use the design proposed in the evaluation kits. ...
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73 views

Key fob receiver reverse engineering: IC identification

I'm doing reverse engineering on a hardware of an equipment, this equipment is able to identify the presence of a RF signal from a key fob. Unfortunately, it was not possible to identify the ...
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34 views

RFID reader array using row/column RF switches (multiplexers)

I need an 8x8 grid of RFID readers arranged on an 8"x8" board. The RFID tags will be placed only millimeters above each antenna. I was wondering if I could use one 1:8 RF switch (e.g. pSemi PE426482) ...
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35 views

RFID (13.56MHz) GND plane over antenna

I dissasembled multiple RFID devices to study their design. The following reader attracted my attention: This is a four layer PCB, the anntenna seems to be 4-turn symetric and is layed out on the two ...
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2answers
44 views

LF RFID signal jammers

I am currently researching into the security of RFID based access control in relation with jammers. For an experiment, I am trying to build a device that can jam 125 kHz RFID cards from like a meter ...
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1answer
100 views

How to mitigate common mode noise introduced by the (LF) RFID antenna driver (on un-earthed SMPS)

When powering my RFID reader board using a SMPS without GND-PE connection, I can observe quite an amount of common mode noise: ~340Vpp from mains. ~4Vpp @ resonant frequency of the antenna. (This ...
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1answer
58 views

Building a UHF RFID Reader, FCC regulations?

I've been working on a project that involves tiny UHF transponders (ex. OMNI-ID Fit 220) that fit into a product with very limited space. We wanted to build our own reader (5 or 6 of them) because it'...
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1answer
28 views

Designing a low-cost, low-performance UHF RFID antenna 902 - 928 MHz

I use UHF RFID readers to read Gen2 RFID tags. Here's the reader I use but it could be any equivalent reader configured to run at 902 - 928 MHz. https://www.digikey.com/product-detail/en/thingmagic-a-...
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2answers
73 views

RFID reader(125kHz) switching between antennas

My arduino application wants multiple separate cards in multiple separate (nearby) locations to be readable at roughly the same time. I am using a RDM6300 module, with a multiplexer to switch between ...
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1answer
66 views

How to identify remote keyless entry (RKE) frequency?

I need to design a system able to identify which frequency is being used by remote keyless entry (RKE). I found that the wireless carrier frequency can be 315MHz in the US/Japan and 433.92MHz (ISM ...
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42 views

Prevent Reception from an Extended Distance (Beyond Design)

I have a magnetic field that is being induced onto a power line by a transmitter, which is following the length of the power line to the receiver. The receiver communicates via a loosely coupled coil ...
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55 views

I am not able to get any response from ST25RU3993 via arduino SPI

I ran out of clues of what could be stopping me from driving the ST25RU3993, hopefully I can get some useful directions from here... I am trying to drive the ST25RU3993 Eval board using SPI, with my ...
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46 views

Why does different antenna inductivity influence LF-RFID performance?

I'm experimenting with LF (125kHz) RFID reader antenna design. And trying two different antennas yields very different results in terms of read sensitivity. Even though one antenna is driven with ...
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1answer
36 views

Power received by RFID tag

Power calculation from E and H field Following from the previous post above. The user provided me with some assistance however I am still a bit unclear on how to apply the equations provided. Could ...
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11 views

Is HID 125 kHz mini mullion proximity reader Compatible with Suprema DM-20 and Corestation?

Can we use HID Proximity cards and HID 125 kHz mini mullion proximity reader for suprema DM-20 and Corestation Controller using wiegand connection? If they are compatible how many DM-20s would be ...
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1answer
56 views

Power calculation from E and H field

I am using gprMax to simulate my design. The design is shown in the picture. It consists of an RFID system inside a steel structure. The transmitting antenna is placed in the middle of the container ...
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11 views

rdm6300 RFID module issue

Can RDM6300/RDM630 module be used as an RFID Writer? im already managed to use it as a reader but can find out how to implement the writing function can somebody help me?
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1answer
35 views

Power supply filtering RCL-filter vs alternatives (for LF-RFID driver)

simulate this circuit – Schematic created using CircuitLab This schematic is the manufacturers dev-board design for the RFID-IC power Supply, using a large power inductor at 4A I_RMS and 22uH. ...
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95 views

Can't find Fast switching BJTs

I'm looking for a replacement for a FET switch that switches at 40 kHz. When the FET is on it is connecting an RFID antenna to ground. When off, the antenna is open. It does this in order to ...
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1answer
79 views

Arduino RFID Multiplexer Antennas

I want to make a electronic chessboard that detects the position of every piece on the chessboard. Every chess piece will have RFID tag. My idea will be to have 2 multiplexers(1*8) one for the rows ...
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1answer
25 views

Simulating RFID coil with FEMM

Is it possible to simulate planar coil printed on a PCB with FEMM? The only idea that come into my mind is to have 2n (if n is the number of turns) regions, each region represents a copper trace and ...
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26 views

Separate antenna in specific (or similiar) RFID reader?

I'm just wondering if a specific (or similiar) RFID reader has a seperate antenna or if it is part of the board. Here is a link to the one I'm thinking of on amazon: https://www.amazon.ca/gp/product/...
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2answers
48 views

Optimizing HF (13.56 MHz) RFID reader antenna for the smallest RFID tag

I want to use currently the smallest (3.2x3.2 mm2) HF RFID tag from Murata LXMS33HCNK-171 together with RFID reader based on MFRC522 RFID frontend from NXP. In my application, the maximal distance ...
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27 views

RFID/NFC transponder with current delivered via wire

I'm sure everybody here knows how RFID transponder works, reflecting radio waves and receiving them at the source. I'm looking for the same concept, but instead of the input to the transponder being ...
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25 views

How can I remove the return paths for a series of circuits and still know when they are completed? NFC/RFID? Multiplexing? Goubau line?

Apologies for the vague title. And know that my electronics knowledge is rather limited. Also my circuit diagrams may be incorrect. I currently have something like this, which represents contacts on ...
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25 views

EM18 module + Raspberrypi

I am using EM18 RFID module. When I connect Module alone to 12v supply it works great but when I connect raspberrypi also to the same 12v supply to power (12v to 5v using buck converter) then EM18 ...
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78 views

Large NFC/RFID reader antenna around a screen

I would like to have an NFC/RFID reader with a screen around 7", where one could tap the card anywhere on the screen to have it detected/read. I do not need to know where the card was placed (...
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1answer
86 views

PN532 (SPI) how to get firmware version

I am trying to use PN532 for Mifare card reading on STM32F4. Before even trying to go forward I have tried to read firmware version to verify that all works ok and cannot do it. I am trying to base ...
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1answer
60 views

How to measure inductance (and more) of DIY LF (125kHz) RFID antennas

When winding my own coil two factors seem most important, inductance and serial resistance of my antenna. However measuring inductance doesn't seem that easy. Ideally I need an LCR-meter that is able ...
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38 views

Is there a difference between read range and read speed/sensitivity in LF RFID applications

If I want to read 125kHz tags but my antenna oscillates at 130kHz, read range will suffer given that the antenna has a low enough Q-factor to still excite the tag at 125kHz. My question is, is there ...
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1answer
70 views

My cellphone is acting as an RFID tag? [closed]

I bought a cheap keyboard emulating RFID (miFare) reader for my PC. I just noticed that the reader can 'read' my cell phone (Pixel 1 XL). Every read seems to return a different serial number. I can ...
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1answer
31 views

Ethernet cable react with anti-theft RFID gate

Yesterday I was leaving a shop, I had an ethernet cable in my backpack, and it reacted with the anti-theft gate, causing a false alarm. I was just wondering why.. I had also other cables (hdmi, power ...
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1answer
24 views

Passive RFID design assistance

I am looking for the correct RFID tag/reader system for my design. The general block diagram of the system is above. The requirements for the system are as follows: Passive tags of some form and an ...
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1answer
50 views

RFID reader technology

Hopefully this isn't too broad of a question, I will narrow it down the best I can. We need to add RFID tags to feeders on our pick and place machine, to determine that they are loaded into the ...

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