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Omnidirectional RFID UHF antennas with medium (~25mm) range recommendations?

penguin

Please bear with me as I couldn't even be considered a novice yet. I'm just a coder with an idea that I want to try out using RFID technology.


I want to identify and record data from passive RFID tags that are up to approximately 10 inches (25 cm) away from the device in any direction. There may be a few inches of low density foam between the antenna and the RFID tags. Small size and weight are important factors. Number of simultaneous tag reads... let's say, up to 5 at a time.

Based on my online research, I've come to the conclusion that a UHF reader is the way to go however, it seems like all antennas are either very short (few inches) or very long range. Can anyone recommend some antennas that might be suitable for these requirements?

Thanks in advance.

  • 0 in reply to anniel747

    It's close, but part of the discrepancy is because the board is for (hopefully) different patch antennas, not just the Kyocera one.

    Since the patches are of different dimensions, it ended up that for this particular antenna, it won't be completely symmetrical (whereas for some smaller Taoglas and Molex GPS antennas that Jan and I tried in some blog posts a few weeks back, those would be symmetrical on this board (and might matter more for GPS, so I figured it may be better to compromise the board for ISM unfortunately). Since not all the patch antennas may be close to 50 ohm, I needed some space for matching.

    Also with hindsight I should have removed some of the solder resist on the ground plane, to make it easier to attach the test cable for the VNA (I had to scratch it off!). Anyway, that can be a future revision maybe.

  • 0 in reply to shabaz

    Wow, thanks so much. 
    I hope to revisit this soon. I ended up getting by with a very early PoC by using multiple PN5180 readers. Not nearly the range I wanted, but OK for just tipping my toes in the water. 
    (and I'm in North America)
    Definitely gonna get check out what you did here when I'm ready up my game. Still learning lots.

  • 0 in reply to dougw

    Thanks! I ended up doing exactly this. Doesn't offer the range I was hoping for, but it got me going for an initial PoC. Your suggestion led me to this video which was an enormous help for someone (me) completely clueless on this tech.
    youtu.be/LILzXRFnRbY

  • 0 in reply to shabaz

    So, I'm starting to look at this a little more. Still mostly over my head, and probably a dumb question, but... do you happen to know of an RFID reader to pair with this antenna? I'm trying to figure out how I would utilize an antenna like this.
    My limited experience now is just using PN5180 readers which has reader and antenna as a single unit and ports to wire them (to an ESP32 board in my case). I'm kind of at a loss at how I would even attempt similar with this antenna.
    Initial research suggests maybe a RAIN (UHF) reader.. but those look to be hundreds of dollars and I'm not even sure it's what I need.
    Any thoughts?
    Thanks!

  • 0 in reply to penguin

    Hi,

    RAIN is a very suitable option (in my opinion), and the commercial systems will for sure cost a few hundred $. One chip manufacturer is Phychips, and there are RFID reader boards (modules) on AliExpress, which are lower-cost (the search term for the older generation chips is PR9200), but you'd need to search for code or write your own, for a PC or microcontroller to communicate to it, whereas the ready-made commercial systems will be able to directly connect to a computer and have interfacing software and an API.

    Some of the simpler boards/modules have a serial connection known as UART (a bit like RS-232, but different voltage levels), which could be attached to a PC using a USB-UART adapter cable. I have one of the PR9200 AliExpress modules, it's been on the back-burner to build a little test board for it. But as mentioned, there would be software effort required. If you believe this is the way to go and are interested in writing the code and sharing it : ) I'd be happy to work on the board a little bit, and publish the board layout so you can order it from any PCB manufacturer and assemble it. There are no guarantees it will work since I've not used the modules before (I have worked on a solution in the past that used the commercial systems for retail applications).

  • 0 in reply to shabaz

    Thanks for the info. An intriguing idea (writing and sharing the code). I'd say that a definite possibility down the road. Right now I'm in just kind of fast prototyping mode. Kinda trying to see what works and how well, then go back and try to understand what I did and how I can streamline it. So I think my first goal will be to finish up what I'm doing with the PN5180's. Then probably try something like the antenna you mentioned and a ThingMagic RAIN reader. I want to see how that performs. If it does well, then I'll probably want to look into reducing the cost and going with something like what you're talking about... a more customized, slimmed down solution. I'm actually excited about that prospect. I would love to work on that! Will probably be a process getting to that point though. Will definitely let you know if/when I'm able to collaborate on that.