Question: How could I build an electronic device which disabled the remote interaction functionality of contactless payment cards while not affecting the functions which are accessed via the on-card contacts or magnetic stripe (where equipped)? I am looking for a DIY technological solution that I could implement myself or suggestions about how I may be able to design and build such a system.
NB: The device would be used by me or other owners of such cards to control access to the card's facilities and to prevent fraudulent access. The desired system has no known fraudulent or illegal aspects.
New chip-and-pin cards come with an antenna which is a coil made of five or so turns of wire (fractions of millimeter thick) located typically along the card perimeter. The antenna is connected to the chip which also has the contact pad used for connecting the card to the terminal when not using the wireless technology.
One important design aspect is that all the turns belong to the same imaginary plane - they are "parallel" (no intersections) to each other and the gap between adjacent turns is more or less constant and is roughly the same as wire diameter. See this and this for pictures of the antenna layout.
There's a bit of paranoia about payWave/PayPass contactless payment features (see this, this and this questions on Money SE). People want to keep all the card features (the card body itself, the stripe and the chip) but disable the payWave/PayPass feature.
Once their banks refuse to disable the feature cardholders proceed to mechanical card alterations - they locate the antenna and either drill through it or slightly cut it with a knife. Typically they succeed but I'd be curious to see the eyes of a cashier who sees this card with two ugly holes one of them through the magnetic stripe. Clearly this may raise a lot of concerns and perhaps even cause an arrest in some cases.
Is there a way to go without notable damage?
Basically we have a small chip which we want to stay intact connected to a coil of very thin wires located in the same imaginary plane (no intersections) all embedded into a thin layer of hard plastic and we only want the coil disconnected in any one point so that it no longer forms a closed circuit.
How can this be done without drilling/cutting/punching a visible hole in the card body?