I’ve been a bit behind the curve and only just received my first Paywave card. My wallet now contains a GoCard, the HSBNE RFID card and a Paywave card. To my dismay, tapping my whole wallet results in the error message: “Please use only one card”. I had no issue using the GoCard on the ferry or opening the door at Hackerspace with both cards in my wallet.
So firstly which card have people found to interfere with Paywave payments, GoCard or HSBNE card?
Secondly, would a sheet of 1mm aluminium sheet metal shield a card?
Protected myself from these cards being read in my pocket.
Adding metal to separate the card could work if you get the right shape and
size, but mostlikely will stop all the cards working all together.
I talk from knowledge and prior experience, the go card against the metal
back of my phone stops it working. This is mosly due to the reader sinking
all it’s power into the massive metal thing instead of powering the chip
inside the card.
The HSBNE card is a low-frequency card, about 125kHz, so it’s probably not the culprit. Higher-security cards like the go card or paywave all run on a much higher frequency, often ~13MHz in the credit card formfactor (smaller rfids go higher, up to at least 900MHz). There are standards for anti-collision APIs that should allow those cards to avoid interfering with each other, but they aren’t identically implemented across different types of card.
Any NFC device will have read errors when there is more than one card present. Any shielding will stop communication. As far as I’m aware there is no way to selectively shield one particular antenna reliably aside from removing it from your wallet or other conflicting environment. I can see having two cards separated by an insulator and conductor may work but as for reliability it is something you would have to test yourself. Your conflict when swiping in would be with another 125khz access card rather than with a NFC card. I have NFC cards in my wallet and have never had an issue swiping in at the space.