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Is it possible to connect more than one antenna to a single RFID reader module in order to pick up two different RFID chips at once?

I would like to create an arduino project like this..

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3 Answers

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Is it possible to hook 2 antennas up to a RFID reader designed to be connected to a single antenna? Yes, in 2 ways:

  • As BarsMonster suggested, you could alternating between the antennas with a relay or something similar, so only one is connected at a time: As long as one antenna stays on long enough for the complete query-response conversation, it should work fine.
  • Connecting both antennas simultaneously with a matching filter: then it acts just like one larger antenna; with proper matching, it should work fine.

However, perhaps you don't really need "2 antennas":

Is it possible for a single RFID reader to read 2 different RFID chips at once:

  • Yes, most RFID protocols include singulation so that if you put dozens of RFID tags in front of it, and then turn on the RFID reader, it can read the correct serial number from each and every tag. (The singulation protocol tells one tag at a time to transmit its serial number, so it's technically not "at once", but it's quick enough to be practically simultaneous for most purposes).
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Are there any resources you know off the top of your head that explain how to construct a relay to control the antennas? Would a MOSFET work for antennas on the 13.56GHz range? – Parker Mar 26 '12 at 14:30
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No, unless it is specifically designed to have dual receivers (unlikely).

But, if you ok to read them sequentially - you can switch antennas every 5ms for example - this might work then :-D

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This is what some cell phones do, with MEMS switches. – tyblu Jan 21 '11 at 5:59
Doesn't usual MOSFET work? Even at 1.8Ghz it should be fine... – BarsMonster Jan 21 '11 at 10:02
So you could have two antennas. Say A1 and A2, Once you read from A1 only A2 would be active and then once you have read from A2 only A1 will go on? – user2703 Jan 21 '11 at 10:59
Yes. That would be the idea. – BarsMonster Jan 21 '11 at 11:02
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A related question here, (not sure if I should create a brand new question). Can I operate say 36 different antenna monitoring tags against a grid of small 2" x 2" squares by simply connecting the antenna to something like the NXP AN532 through a multiplexer (N-to-1 multiplexer)? Does such a scheme work?

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Don't ask new questions as an answer. Start a new question or ask follow up questions in comments – Parker Mar 26 '12 at 14:42

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