Methods and apparatus for preserving privacy in an RFID system
A card comprises an antenna configured to generate and receive radio frequency signals, a chip coupled with the antenna, the chip configured to store sensitive information and communicate the information to an authorized reader via the antenna, and a switching mechanism configured to tune and detune the antenna relative to the chip to enable and disable respectively, the chips ability to communicate the sensitive information via the antenna.
1. An RFID device for storing and communicating information to an authorized reader, the RFID device comprising:
a cover;
a substrate within the cover;
an antenna configured to transmit and receive radio frequency signals, wherein the antenna comprises a main portion, a first portion, and a second portion;
a chip on the substrate coupled with the antenna, the chip including an impedance matching circuit, the chip configured to store information and communicate the information to the authorized reader via the antenna; and
a switching mechanism configured to connect and disconnect the first portion and a second portion of the antenna to tune and detune the antenna relative to the chip to enable and disable, respectively, the chip's ability to communicate the information via the antenna, wherein the first portion is electrically decoupled from the second portion when the switching mechanism is in a first position, wherein the switching mechanism causes the first portion and the second portion to be electrically coupled when the switching mechanism is in a second position, and wherein the switching mechanism becomes a part of the antenna and substantially tunes the antenna with respect to the chip in the second position,
wherein the impedance matching circuit is configured to ensure that when the switching mechanism is in the second position, there is a good impedance match between the chip and the antenna, the impedance matching circuit further configured to account for the effects of the substrate, the switching mechanism, and a surface to which the device is attached when the antenna is tuned and detuned via the switching mechanism.
2. The RFID device of claim 1 , wherein the switching mechanism is a button.
3. The RFID device of claim 1 , wherein the antenna is tuned with respect to the chip when the first and second portions are electrically coupled, and detuned when they are not.
4. The RFID device of claim 1 , wherein the antenna is detuned with respect to the chip when the first and second portions are electrically coupled, and tuned when they are not.
5. The RFID device of claim 1 , wherein the substrate is part of a credit card.
6. The RFID device of claim 1 , wherein the substrate is part of an identification card.
7. The RFID device of claim 1 , wherein the substrate is part of a travel card.
8. The RFID device of claim 1 , wherein the substrate is part of a driver's license.
9. The RFID device of claim 1 , wherein the RFID device further comprises an activation mechanism configured to control the switching mechanism, wherein the activation mechanism is user-operable.
10. The RFID device of claim 1 , wherein the matching circuit is further configured to account for the effects of the cover when the antenna is tuned and detached.