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RFID antenna question. Answered

How sensitive is RFID functionality to the length of its antenna?

Specifically, if I had an RFID like this one, cut the antenna and then resoldered it, would the loss in antenna length (I'm guessing about half an inch) affect the workings of the device?

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steveastroukBest Answer (author)2013-07-17

Its more to do with the change in open AREA and any change in the number of turns, not the overall wire length - you aren't making a 1/4 wave dipole for high microwave frequencies.

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Kiteman (author)steveastrouk2013-07-17

So, if the coil were rewound, with a diameter of, say, an inch, the loss in area would cut its effectiveness?

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steveastrouk (author)Kiteman2013-07-17

This, to my mind, is the go-to paper on the subject
http://ww1.microchip.com/downloads/en/appnotes/00710c.pdf

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steveastrouk (author)Kiteman2013-07-17

Yes, although it can perhaps be compensated by the number of turns on the coil.

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