I love my Oyster card. It's just a bit big...

Has anyone tried cutting down their oyster card to a much smaller
size? Assuming that the smartcard itself takes up a fraction of the
area, that is. After all, this is how the current mini-SIM cards in
mobiles developed from the full credit-card size SIMs...

My main concern is the RF antenna - probably it does run the whole
length / width of the card, and such an operation isn't possible. ISTR
the way these cards work is that the RF energy is enough to power the
card circuitry for the brief period needed to process the transaction;
and this requires a decent-sized antenna.

As to why I want to do this..? Well, it might be quite handy being
able to tape the 'card' to my watch strap, or to my key ring, or
inside my coat sleeve, for example...


Damian