Antennas for ID-2 and ID-3LA

NOTE: This information also applies to the ID-3LA reader. Sparkfun sells a lot of amazing electronic parts very appropriate for prototyping, I use it a lot! One of the things I have been using lately is the ID innovations series of RFID readers (ID-12 and ID-2). They are super easy to use and to integrate with the Arduino platform.

Nonetheless, one of the problems I run into, and from my Internet searches I could see many people did too, was the antenna. While the ID-12 comes with an internal antenna, the ID-2 doesn’t. Having an internal antenna is perfect for prototypical because you just need to wire the reader to the Arduino and off you go. You are reading RFID tags in minutes. However if you start playing with the physical design of your device then you would like to move the antenna to a different place than the reader is, and then the ID-12 is not the piece you need anymore. You could, of course, buy your own reader IC, design a PCB for it and place the antennas and the respective resonance capacitors wherever you want, but… ain’t that quite some work for simply prototyping? I don’t even have an easy access to a PCB printer.

(I came across all this while working on a beefed-up 4×4 super version of the Rabbit)

Then I bought the ID-2 (which despite not having an internal antenna it does have a resonance capacitor) and set to find a matching antenna for it. Man, that’s hard! The point is that you either have to wind it yourself (which off course kills the passion of quick prototyping) or buy it from the market. There are thousand antenna providers out there, but it happens that no-one sells then small <2cm and with the needed 1.08mH inductance.

Well, almost no one, and this is the good news. I was looking into the catalogues of antenna providers until I found CoilCraft, these guys had one that almost matched what I needed (1.08mH capacitance but double axis, I needed it single axis), the 4308RV series at 1.08mH. I bought some of those antennas and they work as magic. However, I realized the antenna shape would make it difficult to build a really slim reader, so I started looking again for a Z-axis antenna. I wrote CoilCraft about it, but they didn’t saw any value in custom making those for me (I said I would buy 50 :|).

Until I found the Spanish Grupo Premo ( These guys had some Z-axis antennas but not at the require inductance for the ID-2. I went ahead and asked them to custom make the one I needed, and send me samples for free (quite a move) and to my surprise the guys said YES, and I have now received samples from two of their antennas (3 samples of each model) and they work as a dream.



So, if you are prototyping with the ID-2 and need a small and reliable Z-index antenna go to the Premo group. And don’t ask them for samples, they will be happy to sell you any amount starting from 1.


(iPhone picture of the samples I received)


53 thoughts on “Antennas for ID-2 and ID-3LA

  1. Hey there dude,

    I’m looking at incorporating a reader into a wrist band form factor.
    Like you i was looking at the ID-2, but it needs an external antenna.

    It is stated that you need an antenna with 1.08mH inductance.
    Looking at the website they list them but they are 2.28mH

    Could you possible update a link the your 1.08mH version, or where they just one offs?


  2. Hello Scott, I actually wrote to the Grupo Premo guys and, although the 1.08mH version of the antennas was not listed, they were very happy to custom make them for me. As it is shown in the picture I received three samples of each and they worked perfectly. I am currently in talks with them to buy a bunch more of each that I am needing for my project.

    I guess the best you can do is to drop them an email. Another option would be to go for the CoilCraft antennas, if the form factor works for you of course.


  3. Hi,

    Thanks for getting back so quickly. I have send an email to the guys at Grupo Premo so i’ll see what they get back to me with.

    Could you send me the link for the ones at CoilCraft? i couldn’t seem to get a picture or the dimensions.

    On a side note, what was the read range like for the antenna that Grupo Premo sent you?


  4. hello, I’ve found your blog when looking for an antenna for my id-12 rfid reader.

    I saw that you suggest two vendors and that the antenna I’ve to buy must have 1.08mH inductance for your ID-2, how about ID-12? Have I to buy an antenna with the same inductance?

    Thanks, Davide

  5. Hi! Thank you for the very useful blog post! Can you let me know what range you found (to a standard 125kHz ISO card) with the Coilcraft antenna?

  6. Hello,

    Came here from SparkFun and also looking for an antenna.. but I don’t understand exactly the difference between double axis, single axis coil. Single axis is same as z-axis ?

    Also, maybe I’m stupid, but I don’t see any spec that gives size dimension on coilcraft site,
    but looking at your photo, seems small enough.. 🙂

    Anyway, many thanks for writing this blog entry!

  7. Hello SFR75,

    First, thanks for coming all the way here from Sparkfun. It’s for people like you that I created the post and linked to it from the Sparkfun website. Let me start with the single axis, double axis thing. An antenna has a coil, which is a metallic line wound up on itself. This coild generates an electromagnetic field perpendicular to the center of the winding. Now, when this things are produced for being mounted on a PCB, when you look at them from the top, the circumference of the coil is either facing you (se can see a ring) or you’re looking at the coil from the side. In the first case the electromagnetic field of the coil is vertical/perpendicular to the surface of the PCB. So if the PCB is built on the X and Y axis, then this king of antenna is a Z-axis antenna. The other antennas don’t have a particular name as far as I know.

    Now, single axis or double axis. As you can imagine an antenna being a coil, the electromagnetic field will be created on both sides of the coil — and thus general antennas are called double-axis. For a z-axis antenna it means that the vertical field both goes up from the board and under the board. Following a special building procedure similar to putting a mirror on one of the sides, the electromagnetic field can be focused only on one of the sides — transforming the antenna on a single-axis antenna.

    Finally, in relation to the dimensions for the coilcraft antennas. You can find them under the “specifications” heading, or you can go directly to this link (

    Juan David

  8. Hi Juan, this is great post I really appreciate it. I like many have come from Sparkfun. I’m looking to use any of the ID series and am trying my best to find an antenna solution that will give me approximately 2.5 inches of range. This is obviously a challenge.
    Form factor is not as big an issue for me, so I wanted to ask what kind of range you got from the Coilcraft antennas. The read distance on the page you linked is listed up to 40 inches. Now I assume this is best case, and I would likely at most get a quarter of that, but 10 inches is still more than enough.
    Is there any truth to these numbers or is the read distance more likely to be an inch or less. Also will any of the units on that page work well with the ID-2?

    Thanks Again,

    • Hello Asa,

      Thanks for your comments. My experience with these antennas is that they normally read within 2 inches. But I should also say that I have always been using the glass-capsule RFID tag… meaning that for a tag with a larger antenna the reading distance should be larger. I hope this is useful!

      Juan David

      • It certainly is. I am using button tags, although not those sold on Sparkfun. Perhaps the best thing to do is get spamples from the site and see what happens. Could you advise me on which ones would work with the ID-2? Also I am not sure which tolerance option, 5% or 2%, would be better. Thanks again. Asa.

      • For the ID-2 you should get any at 1.08mH they would work perfectly with the internal capacitor. As for the tolerance… I honestly went for cheap — that is 5%!

    • Hey there,

      I have been using the ID-2 chip with an external antenna. I have struggled to get a good read range from the smaller coil craft antenna.
      I used the larger copper coiled (about 1 inch by one inch [Square]) antenna and could get about 1 – 1.5 inch read range.

      The read ranges on the coil craft webpage are obviously dependent on how good (strong) the chip is – i got about 0.5 – 1 inch with the coil craft antenna’s.

      Hope this helps,

      • Well its a little discouraging honestly. My project unfortunately hinges on being able to get at least 2 inches of range or so. The chips are embedded inside capsules that are 2 inches in diameter. And due to that fact I can’t use chips that have a larger form factor, like a card. Can you point me to the larger copper antenna you used? Thats at least approaching the distance i’m looking for. Also any advice on ways I might be able to get that last bit of distance?
        I appreciate the help.

  9. Hello,

    I’m using ID-2 with a external antenna for my university project.but bit confused about the ID 2 circuit diagram in the data didn’t shows that the pin 1 needs to connect to the GND.But in the pin description it clearly mentioned that pin should connect to the GND.Even in ID 12/20 circuit diagrams pin 1 connected to the GND.please help…


  10. A year has gone by since your original post… do you maintain your recommendations on antennas for the ID-2? Or have you found something better?

  11. Is the Coilcraft antenna a single axis/z axis antenna? The Dimensions drawing looks like an x/y axis antenna. My second question is what kind of connection do you use to the ID-2? Coax? Twisted Pair? Straight wires? What gauge?


  12. That looks like a good switch, it should do the job. In my case it was doing about 3 antennas per second, don’t have the exact number, but it wasn’t more than that.

    • Ciao ho trovato il tuo post molto utile.
      Volevo chiederti che tipo di swich hai usato per gestire le antenne con il multiplexer.

  13. hi,
    I found your blog very useful!
    I wanted to ask swich information that you used for the multiplexer you have recommended to Scout.
    thanks in advance for your advice

  14. Hi, I bought the id-2 and antenna, but I don’t understand how to connect the antenna using internal tuning condensator. Can you help me?

  15. In first tests i used an ID-20: I connected pin 7 and pin 1 to ground, pin 10 to a led with 330 ohm resistor, pin 11 to 5 volt and pin 9 to send data to a pic.
    Now, if I connect the id-2 through pin 3 and 4 to an external antenna it doesn’t work, how is it possible?

    • Well, it’s hard to say Paola… What I can tell is that it’s worked for me before as I detailed in this post. Your best shot is to check step-by-step (via voltimeter or some other tool) that all connections are working. I hope this helps!

  16. I bought an antenna from core RFID company which according to their website is good for the id 2, but after I measured it, I saw that it had 1.54mH of inductance. So I removed the coils up to the value of 1.08mH, but even in this case it worked.
    They recomended me to buy the id3la that has more or less the same characteristics of id2 but it works with an external antenna of 1,337 mH because its internal tuning capacitor is 1N2.
    do you think I’ll have the same problems of id2?
    I also contacted the grupo premo company recomended by you but they told me that to make me a custom antenna I have to send them the business plan of my project. Also in this case, what should I answer?

    • That’s hard for me to say Paola, you will have to try it on your own. As for the business plan… well, I guess you better tell them the nature of your project. If it’s an academic project then you should just tell them so. Good luck!

  17. I am working on a project for senior design involving RFID. The problem I am having is that i am using an id12 which is for short distance. I need something that will read from at least 4in. This also needs to be a passive system.

      • It doesn’t need to be exact. I just need a distance further than the 2in that i am getting. This will be used for detecting a certain animals presence by attaching an RFID tag to the collar. I have looked into the ID20 but it still doesn’t give the range i am looking for. Anyone who has any ideas feel free to comment. I found this blog after intense research into my problem and decided to see if anyone has ideas.

  18. Thanks for the help! I have heard that their range is much smaller than what is given. I guess I am going to have to buy something that I can design my own antenna for.

    • Hello Bonne, a custom antenna is a great idea. However I would stay away from building my own, unless you really know what you’re doing. What I would recommend is to buy an antenna/capacitor pair that will give you the distance you want. See providers like coilcraft or premo for options.

  19. Hi Juan,

    I’m working on a project that would require multiple antennas on one ID-3LA reader. I read from the previous posts which type of multiplexer you used. However, it is possible that you post the circuit you built to control the multiple antennas?


      • Hi Juan,

        Thanks for the quick reply! I understand that it’s been a few years since you’ve posted this. Is there any chance that you may still remember how you had connected the multiplexer/demultiplexers? Did you had to use an analog multiplexer at the antenna output and another analog demultiplexer at the antenna input? I am currently having trouble with the antenna output as the Vpp goes up to ~60V and normal demultiplexers only allows for around 20Vpp. Did you have to use resistors to bring down the voltage input and if so, did that effect your read range significantly?


  20. Hi
    i have an arduino project + RFID reader ID-3LA and i want to make an antenna with a range of 50cm.
    is that possible and how can i make it if it is ?
    thx a lot

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