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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.

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  • 0

    You didn't mention what region you require operation in, but if it's Europe, then this antenna looks ideal and is low-cost:

    https://www.digikey.co.uk/en/products/detail/kyocera-avx/9000468/21442857 

    It is omni-directional, and I suspect (can't guarantee it, you'd need to try it) that it may support the range you're looking at.

    However, you'd need to mount it to a 70 x 70 mm ground plane, which is pretty easy to DIY (you can get the PCB ground plane manufactured for sub-$10, even in single quantity, from many PCB manufacturers in China).

    If you're in North America, then this antenna looks suitable:

    https://www.digikey.co.uk/en/products/detail/kyocera-avx/9000469/21442939

    Again, it requires the 70 x 70 mm ground plane. If you need more info about how to make the ground plane, let me know.

    (And again, no guarantee it will support the range you're looking for, but at the low price it's definitely worth a shot.

    The ground plane will end up looking something like this (the example here is for GPS, not RFID, but it will be almost identical).

    image

  • 0 in reply to shabaz

    Measurements!

    The results are not significantly different from the datasheet, for almost 2/3 of the frequency span. I wouldn't expect it to be identical anyway since there's no guarantee I tested in the same environment or the same orientation. I happened to test with the antenna facing vertically upwards.

    This was my first time using the NanoVNA (there are different models, I have the -H4 model) to measure an antenna. Impressive how good it is. Now I understand why people rave about NanoVNAs, it's justified.

    image

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  • 0 in reply to shabaz

    Measurements!

    The results are not significantly different from the datasheet, for almost 2/3 of the frequency span. I wouldn't expect it to be identical anyway since there's no guarantee I tested in the same environment or the same orientation. I happened to test with the antenna facing vertically upwards.

    This was my first time using the NanoVNA (there are different models, I have the -H4 model) to measure an antenna. Impressive how good it is. Now I understand why people rave about NanoVNAs, it's justified.

    image

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