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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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    That's quite normal, because a lot of antennas need some distance (far-field) to perform well. Whereas, in the range you're looking at (near-field), you're likely at the extremity of signal strength at 10 inches at UHF for near-field antennas. Compounding that, is that you're looking for a very wide radiation pattern which means signal strength will not be concentrated.

    I'm no expert, but I suspect you might need a far-field antenna positioned at a greater distance (I don't know your application). The far-field antenna at a distance will get you the coverage you desire without the need for a closer (near-field) antenna with omnidirectionalty I think. It's probably worth talking to either an antenna manufacturer or the RFID reader manufacturer (who will be quite experienced because they know what their customers use).

    Also, tag antenna shape/size will make a big difference, so you might want to experiment with several (assuming that's something you are able to modify in the solution).

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  • 0

    That's quite normal, because a lot of antennas need some distance (far-field) to perform well. Whereas, in the range you're looking at (near-field), you're likely at the extremity of signal strength at 10 inches at UHF for near-field antennas. Compounding that, is that you're looking for a very wide radiation pattern which means signal strength will not be concentrated.

    I'm no expert, but I suspect you might need a far-field antenna positioned at a greater distance (I don't know your application). The far-field antenna at a distance will get you the coverage you desire without the need for a closer (near-field) antenna with omnidirectionalty I think. It's probably worth talking to either an antenna manufacturer or the RFID reader manufacturer (who will be quite experienced because they know what their customers use).

    Also, tag antenna shape/size will make a big difference, so you might want to experiment with several (assuming that's something you are able to modify in the solution).

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