On Fri, Oct 7, 2022 at 6:38 PM Rich Pieri <[email protected]> wrote:
> On Fri, 7 Oct 2022 17:58:28 -0400 > Bill Ricker <[email protected]> wrote: > > > Sleeves may not be a perfect cage, not having a TEMPEST grade > > closure, but even a poor Faraday cage may add just enough dB > > attenuation that the extreme range RFID/NearField/whatever doesn't > > pick up the card in the sleeve in the wallet. > > I have used prox cards through RF sleeves. Need to get the angle right > but it works through sleeves that block face-on transmission. > Sure. It may even have antenna GAIN in that ONE direction. [see Smashed Donut Theorem] Still gives you a fighting chance at least. And if you learn by experimenting which angle WORKS for using a protected card, as you've done, do NOT give THAT angle when NOT paying with the prox card. Also, your meat-pincers (finger&thumb) pulling the other card out of the sleeve are attached to a dirty bag of water (hand), which will provide quite a bit of E-M shielding to the maw of the sleeve when trying to extract from, rather than trying to aim, the sleeve. (OTOH if you only have ONE tap card and the other is CHIP&SIGN or CHIP&PIN only, the other doesn't need to be in the sleeve, which might then remain pointed harmlessly at the ceiling for the entire operation.) -- Bill Ricker [email protected] https://www.linkedin.com/in/n1vux _______________________________________________ Discuss mailing list [email protected] http://lists.blu.org/mailman/listinfo/discuss
