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Need suggestion for improving the tag detection range (Reading distance)

Maddineni
Intellectual 525 points
Other Parts Discussed in Thread: MSP430G2553, TRF7970A, TRF7960

Hello,

We have designed an RFID reader device by using TRF7970A and MSP430G2553 and a PCB antenna whose dimension is 50mm*40mm.

Power supply for the system is 3.3V and hence the maximum RF power output we expect is 70mW (Correct me if it is wrong). We are using the TI tags, Tag-it HF-I plus transponders (ISO 15693 protocol).

With these configurations, we are able to read the tags at a distance of 8 to 9 cms whereas, we are having a requirement for 25-30 cms of reading distance. As we are looking at a miniaturised product, we couldn't increase the size of the antenna which can help in increasing the reading distance. 

Can you please suggest us any solution regarding this requirement?

Note: We came across an application note from TI which is using TRF7960 and multiple antenna boards multiplexed to the single reader. Can this be a potential idea for us to go forward?

 

Thank you.

Regards,

Maddineni

  • 0
    TI__Guru*** 128185 points

    Hello Maddineni,

    You are already getting a very strong result based on your implementation and the TRF7970A output power limits. One thing you can do to extend the range a bit would be to source it with 5V in order to maximize the output power. However I don't think that alone would get you to 25-30cm.

    For a range that long, you will need to output more than 70mW, and need a larger antenna as well.

    See this pdf which highlight read ranges with various devices including the TRF7970A for some idea on what would need to be done to achieve that range: 0246.TI HF Reader and HF Tag Read_Ranges.pdf

  • 0 in reply to Ralph Jacobi
    Intellectual 525 points

    Hello Mr. Ralph,

    Thank you for the comparison sheet.

    Yes, Increasing the output power and antenna size is what we are looking at but, as we are currently compromising on the antenna size due to our design constraints will the multiple antenna implementation be a better option for us?

    Thank you.

    Regards,

    Maddineni

  • 0 in reply to Maddineni
    TI__Guru*** 128185 points
    Hello Maddineni,

    The multiple antenna implementation is to allow a single NFC reader chip locate an RFID tag at multiple locations. For example, if you have a system where a tag can be presented in 4 different physical locations, then you could multiplex the antennas so that you only need 1 NFC reader IC rather than 4.

    It would not help you gain additional range away from the system, but it could give you a wider area of which a tag can be presented if you use multiple antennas in multiple locations on the surface of your product.

    Hope that clarifies what the multiple antenna implementation does for you.
  • 0 in reply to Ralph Jacobi
    Intellectual 525 points
    Hello Mr. Ralph,

    Thank you for the detailed explanation. Yes, that makes clear about the multiple antenna concept.

    Longer reading distance is what we required but as I said in my previous post we are strictly restricted in the case of antenna size. We are pretty sure that increasing the output power alone will not yield the desired requirement.

    By looking at the multiple antenna implementation we felt that it might suit our application where the tag can be there at any place in the space of 35cm*20cm*12cm.

    Thank you once again for the suggestions.

    Regards,
    Maddineni