SparkFun Simultaneous RFID Reader + UHF RFID Antenna +Ultra-Small UHF RFID Tag Rain not working

Sensors NFC & RFID
1

Hello everyone, let’s see if someone can give me a hand, because I’m about to go crazy :cry: . My intention is to read several RFID tags simultaneously within a range of less than 1m. To do this I have purchased the following products (in principle all compatible with each other):

I have the reader connected to a lab power supply that provides 5v continuous and a limit of 1.5A. This power is provided by the 2mm JST connector, and I have the JP1 junction cut so that the FTDI only provides communication with the module and not power.

For testing I have used the Jadak Universal Reader Assistant (URA) software. If I read the tags with the integrated antenna they work at a very small distance, but they work.

After buying the external antenna I mentioned before and desoldering the solder that gives the antenna from the PCB and soldering the one that gives the u.FL connector the board in principle is ready to work. I have configured URA with several regions, OPEN, EU3, EU4, NA, among others, selected antenna 01, varied the read/write power with several values (even reaching the maximum 27 db). With no configuration I manage to read a tag that is above the antenna (not to say far away a finger, or a few centimeters). I have checked the soldering and desoldering to the external antenna and the connector, everything is correct checked with a multimeter. I have checked that the antenna ground leads to the rear metal part of the antenna. I have checked the wires and everything is ok.l However, I am not able to read any label when before with the PCB antenna at least I could read some even if it was very close.

Can anyone think of what I might be missing? I honestly don’t know what is going on, because it is not normal that the label placed on top of the external antenna, touching the white plastic, I am not able to read any label.

Thanks in advance.

2

1- You’re not going to get 1m range from those tags. Maybe an inch or so max.

2- You need a special antenna for the tiny tags. See the link below.

https://www.sparkfun.com/products/15113

3

Hello, thank you for your reply. In principle I am not looking for 1m with 60 cm left over for me. However, I know that the internal antenna of the labels is a limiting factor. However, could you explain to me why the antenna is not compatible with the tags? As far as I can understand the antenna works in the same frequency range as the reader and the tags, so there should be no problem with that. Therefore, working on the same frequency, at least the label placed on the antenna should provide its UID.

In fact these tags are even intended for medical applications, it seems illogical to use an antenna like the one you provide in the link that is not able to give any range because it is integrated in a PCB.

Best regards, and thanks again.

4

The ring antenna focuses rf energy to a small point to read the small tags. The small tags also don’t radiate much rf energy back at the antenna because of their size further limiting their useful range.

Think of the big antenna as a floodlight that shines a wide beam of light over a wide path and the ring antenna as a laser that shines a narrow focused beam. One is good for “lighting up” large objects at a distance and the other is good for smaller objects. (Or tags in this case)

5

I know that the shape of the antenna is important, and again that the antenna on the tags is tiny. However, whatever the antenna is attached to the reader, isotropic, omnidirectional, linear, if you place the tag on all surfaces of the antenna, it should at least provide a reading at some point since the tag is fully attached to the antenna. Also, if it is the shape of the antenna, the one that incorporates the sparkfun simultaneous rfid reader itself and this one works, not being the same shape as the antenna you propose in the link.

Sorry for the insistence, but being all of the same frequency at some point should provide readings regardless of the shape (I admit that at high distances no, but less than an inch or placed on the surface of the antenna yes), at least is what I understand.

6

being all of the same frequency at some point should provide readings regardless of the shape

Well, you’d think so but sadly physics gets in the way sometimes. :frowning: