“Our E-470 tollway has a windshield sticker no bigger than any other RFID and can be read just fine. Highways are now getting all kinds of fancy electronics and I have no doubt that they could read an RFID in your wallet or purse.”
YOU’LL NOTICE those antenna (the Yagis seen at the toll booths pointing down at trafic!) used are in the 900 MHz range.
This a FAR CRY from the 200 kHz ‘coupled fields’ systems used on merchandise (and library books!)
Too many ppl believe in ‘magic’ on this stuff; where are all the board EEs and physicists?
“where are all the board EEs and physicists?”
I am both, including RF engineering. While those library book and merchandise stickers operate, as you said, in a coupled field effect, so do the new highway tags. While it takes more energy and a larger antenna to do the job they can still read that itty-bitty RF ID tag.
In fact, the one for my motorcycle is a little fella that is barely visible mounted on the front of the headlight. The sticker is about 1/2” by 2.5”, the chip is about 3mm in diameter and the antenna for it is a few inches long.
So, if the DMV wanted to place a very readable tag in their driver’s license, no problem. Easily done.