[RFI] RFID cards

[George Gorsline VE3YV]

Having worked in the business, there are a number of things that come 
into play with RFID or NFC (Near-field cards).  Suffice it to say that 
the cards in your wallet require a very short distance to be read 
(transmitter sends pulse which is used to power the card response), both 
because the card is using the power received to send the data back and 
the practical considerations: you don't want to read the card of the 
next person in line at the counter or get two responses, forcing 
re-tries until a clean one is received.  Could you use a very power 
power transmitter to extend the range?  Theoretically, but 
inverse-square law and multiple hits make it highly unlikely.
The transponders for highways are quite a different system as they are 
expected to be read over a much greater distance. 
Many types of chip cards and frequencies used (LF, HF, VHF, UHF) exist.  
Also, responses vary from fixed plain text responses to lots of 
encryption, and some chips that have re-writable areas which could be 
updated on the fly and could be used to disable the chip.
Sorry to spoil your fun, but no conspiracy and lesser risk.  If you want 
to talk risk:  the US still uses magnetic stripe cards, and hasn't moved 
to smart cards with a chip and a PIN with encryption unique to each 
transaction, as are in use in most of the rest of the world and are 
being phased in in Canada.  Add reliance on signatures and then you have 
risks worth bandwidth.  But not on this reflector - now can we go back 
to RFI topics?

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73,  George VE3YV / K8HI