Hi all. I’ve been digging around the net looking for answers to what might be a simple problem. I’ve seen all the RFID shootout videos on Defcon and all the rest and I’m trying to get the read range on my RFID reader upped.
I’ve bought an ID-12 from Sparkfun with the breakout board and all that ready to go. Looking over the schematics, it seems that it is indeed possible to connect another aerial to the the ID12. Now, I have two options it seems:
1)Build a directional one to get more power in one direction only.
2)build a more powerful aerial all round.
The schematic mentions that i should be looking at an aerial with a 1N5 capacitor built in there. Now im thinking that perhaps getting hold of some kind of adjustable capacitor (in a sort of old skool, crystal set style) would be a good idea as simply winding a large coil of copper wire is a bit rough and ready.
I have a similar aerial on a mifire unit though. This works at around 14MHz though as oppose to the ID-12s 125KHz. Clearly, this means tuning the aerial till it works. Finally, I presume in the second case, I’ll need an amplifier right?
I don’t think that the ID-12 supports an external antenna. For that you would need the ID-2. Changing the antenna size or configuration won’t necessarily give you any improvements in read range. You will be limited by the amount of antenna current the module can provide and the sensitivity of the modules detector, amplifier, and filter circuits. It wouldn’t be very feasible to add an amplifier to any of the ID modules.
The power that these things supply is indeed a limiting factor. However, the ID12 and ID-2 do indeed support external aerials according to their datasheet. At the las Defcon it has been shown that certain cards can read up to a mile away! Also, there is the full schematic for a 30cm read range on a mifire card. Mifare runs at around 14Mhz whereas the ID-12 and ID-2 are closer to 125Khz. Now, if it is possible to get the read range up on Mifare, it must be possible to do the same with 125Khz low frequency. I sadly don’t know enough about aerials.
The data sheet shows the antenna pins on the ID-12. I’m not sure if they are actually connected. If they are, any external antenna would be sharing the antenna drive current capability with the internal antenna. This would definitely limit the read range.
Just so you know. I work as an engineering tech for a company that designs and produces 134.2 kHz RFID reader. The maximum read distance you will get is dependent on many factors including the antenna drive current, the Q of the antenna coil, the size and geometry of the antenna, the orientation of the antenna and the tag, the sensitivity of the detector and filter circuits, and others.
I’m not sure what kind of range you are looking for. But, I don’t this the ID-12 or even the ID-2 are viable for anything greater than a few inches.
Ah, in that case, perhaps another RFID solution is needed. Essentially, Im looking to create a field the size of a 17inch monitor. Essentially, one should be able to place a tag anywhere within the perimeter of the screen and have it detected. With HF this seems not to be a problem as Texas Instruments have a set of PDFs describing aerials with very large ranges in comparison with their smaller ones. However, when it comes to LF, I can’t find a thing Thanks for the headsup. It may therefore be better to focus on HF for the above example
hello , i am sorry to cut in but this is the only thread i could find about the ID-12
i bought the ID-12 thinking it can read the Q5 tags like the ID12-WR . does anyone know where i can buy the id12-wr ?
and how do i make the 8-bit micro-controller read the tags ?
also i tried looking for the full datasheets of the ID-12 , i couldn’t find it . so if anyone has it can you please send it to me or point me in the right direction .
Thanks for the headsup. It may therefore be better to focus on HF for the above example