Reading speed Grove 125Khz RFID module

Hi I am facing stability issues with the Grove 125Khz RFID module.

I have connected this reader to an arduino Mega and am using this reader to detect trains running on a traintrack.

On slow speed the reader picks up all tags (mounted underneath the train) however when I increase speed the stability of the reading fluctuates. Sometimes it reeds every lap, but it can also fail for multiple laps.

Is there a way to increase accuracy when the tag is passing with more speed? (maybe a bit vague, but it is difficult to say what the speed of the train (or tag) is when passing the reader.

HI there,

Please try to increase the antenna size. you can make some by yourself. thanks.

Hi, thanks for your reply.

Based on your advise I tried the following.

I created my own antenna using special wire. I used the instructions and references in the following youtube movie (

I also bought a different antenna RFID HQ READER ANTENNA, 125KHz/134,2KHz, Typ MSR45, AIR COIL, LUFTSPULE (

However, both antenna’s are not working with the RFID reader. When soldered on the give no reading at all. When I revert back to the original external antenna the reader works again.

I would still appreciate some advice.

Additionally, can somebody point out the inductance of the PCB for the Grove module?

I am using this calculation tool

<LINK_TEXT text=“ … ircore.htm”></LINK_TEXT>

to calculate the amount of turns (or length of the wire) from the antenna. I could not find any datasheet of the grove module that shows me what inductance to use.

For example, the youtube movie that I shared above uses a ID-3LA module where you can find a datasheet <LINK_TEXT text=“ … D-20LA.pdf”>,ID-12LA,ID-20LA.pdf</LINK_TEXT> that tells that inductance has to be 1.337mH.

Hi there,

it is 475uH. you can refer to 51X82mm. sorry, we do not sale this part yet. thanks.