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Re: [loopantennas] material for inductive loop

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  • Steve Greenfield
    Losses are slightly higher with aluminum, simply because it is not as good a conductor as copper. Every yagi TV antenna I ve seen has been made of aluminum, so
    Message 1 of 3 , Oct 27, 2005
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      Losses are slightly higher with aluminum, simply because it is not
      as good a conductor as copper. Every yagi TV antenna I've seen has
      been made of aluminum, so not too much of a drawback.

      If they are etched on a PCB, it'll be copper. You can plate with
      gold or silver, although gold is a worse conductor than copper.
      It's used on edge connectors simply because it doesn't corrode.
      Silver is marginally better than copper, but I doubt you'll see as
      much effect on range as you will from nearby metal, angle, other
      large objects nearby like bodies and file cabinets.

      Steve Greenfield

      --- doneirik <elbor_x@...> wrote:

      > Dear Group,
      > I am designing an inductive loop antenna for an 13.56 MHz RFID
      > application. (I will probably have the loops etched onto a pcb) I
      > have
      > seen that some antennas are made using aluminium, others with
      > copper.
      >
      > Does anyone here have any experience with different materials,
      > and can
      > tell me the advantages/disadvantages with them?
      >
      > regards
      > doneirik
    • Bruce Carter
      ... Funny - I was just doing that for a customer a couple of minutes ago! First of all - resist the temptation to go too narrow on the PCB traces to get the Q
      Message 2 of 3 , Nov 1, 2005
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        > Dear Group,
        > I am designing an inductive loop antenna for an 13.56 MHz RFID
        > application. (I will probably have the loops etched onto a pcb)

        Funny - I was just doing that for a customer a couple of minutes
        ago! First of all - resist the temptation to go too narrow on the
        PCB traces to get the Q down. You can trim the Q with a resistor in
        parallel. Secondly, make the loop as large as you possibly can.
        These magnetic loops are very inefficient as it is due to their
        small dimensions. Couple that with the low Q's required for this
        sort of thing, and you have one really lame antenna. Of course all
        you want is a few inches most of the time, but more range / better
        reception is almost always desirable.

        Matching always comes up - don't. Do a good loop design, tune it
        with your receiver board and cable attached and powered up. I have
        some really good strategies for tuning without the measuring
        instrument affecting the tuning - if you aren't a competitor or
        something I'll be happy to share with you.
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