ST25R3911 How to read tags at any orientation.

[SurfBytes]

Hello,

I have a scenario where RFID tags may be presented to a ST25R3911 reader at any orientation.

Tags do not read If the plane of the tag antenna is not properly aligned enough with the plane of the reader antenna.

To work around this, I was thinking of using two ST25R3911's with antennas perpendicular or at some angle to each other with the idea that at least one reader antenna will pick up the tag.

The questions I have are:

1. Is this a feasible solution ?

2. Can the two readers be active at the same time or should only one reader be active at a time ?

3. I understand that the ST25R3911 can have two antennas, would this be a better solution than having two ST25R3911's ?
4. Is there a better solution ?

Thanks for any suggestions, I am new to RFID.

-Randy

[Ulysses HERNIOSUS · Accepted solution]

Hi Randy,

ad 1) Sounds feasible

ad 2) When the two antennas are covering the same volume I expect heavy interference if active at the same time. So I would definitely time-multiplex them.

ad 3) Yes, ST25R3911B can have two single-ended antennas instead of one differential antenna. There are some caveats: Field detector can only run on one of them - likely not important for you. And of course in single-ended configuration the achieved output power will be lower.

ad4) I assume you already considered changing the geometry/orientation to cover your most common use-cases. If the tag can be in any orientation then it will always be possible to orient it such that it has zero coupling.

BR, Ulysses

[SurfBytes]

Ok, sounds like time-mux'ing two ST25R3911's is a reasonable approach. 

Thanks for your quick response !