A self-tuning RFID device having an input capacitance that is adjustable in response to a detected signal. The self-tuning RFID device preferably comprises a variable capacitance RFID chip coupled to an inductor, and an input circuit driven by the detected signal from the variable capacitance RFID chip. A change in capacitance with the detected signal is delayed by a specific amount of time, thereby allowing the self-tuning RFID device to function as a dual mode EAS and RFID tag. The ESA functionality can be deactivated by a high field at or near its resonance frequency without disabling the RFID functionality. The effect of the high field may change the input capacitance permanently changing its resonance.

A method for detecting receivers includes a step of detecting a receiver, in which step a general controller detects an adjustable receiver when a general antenna receives a secondary wave emitted by the adjustable receiver, followed by a reconfiguration step in which the general controller commands a controller of the detected adjustable receiver to switch to an interaction mode in which the impedance of the adjustable receiver is alternated between a first configuration impedance and a second configuration impedance in order to detect other receivers. The reconfiguration step is of a duration that is an order of magnitude higher than the duration of each alternation of the first and second configuration impedances.

The invention relates to a chip card designed to communicate data in a contactless mode with a card reader operating at a reading frequency. The resonance frequency of the chip card may change according to the capacitance of the chip used in the contactless mode of the chip card. In order to be able to use various chips without changing the booster antenna design, the card antenna circuit is provided with a capacitance element such that the chip card including the card antenna circuit and the chip module has two different resonance frequencies, one of which being equal to, or lower than, the reading frequency and the other being equal to, or greater, than the reading frequency. This create a broadband wherein the reading frequency falls.

A communication method includes: performing carrier sensing at a predetermined time interval; transmitting first data including ID information of a current radio tag to an access point when a signal transmitted by another radio tag to the access point is not detected during the performing of the carrier sensing and the current radio tag is not in a transmission stop state; interpreting a command included in a signal, when the signal is detected during the performing of the carrier sensing and is not a signal transmitted by another radio tag to the access point, the interpreting being performed under an assumption that the signal detected is a signal transmitted from the access point; and changing the radio frequency of a signal to be transmitted by the current radio tag, when the interpreting shows that the signal includes a command instructing changing of a frequency.

An RF system is provided that includes an RFID card and a reader-writer device. The RFID card includes a substrate, an RFIC element, an antenna coil, and a deformation sensor. The reader-writer device and the RFID card transmit and receive predetermined information between an antenna coil of the RFID card and an antenna coil of the reader-writer device through a magnetic field. The RFIC element transmits the first signal via the antenna coil when the deformation sensor does not detect bending deformation of the substrate, and the RFIC element transmits the second signal via the antenna coil when the deformation sensor detects the bending deformation of the substrate.

Disclosed is an ultra high frequency antenna device for use with an identification tag for attachment to an animal. The antenna device comprises: a meander line antenna; and a substrate. The antenna device is operable to use the body of the animal to which it is attached as part of the tuning circuit of said antenna device. Also disclosed is an ultra-high frequency identification tag comprising such an antenna device, and a method of manufacturing such an ultra-high frequency identification tag.

A wearable payment device, such as a finger ring worn by a user, communicates payment data to a payment reader that uses the payment data in order to request a payment transaction. Such wearable payment device may be conveniently carried by and accessible to the user such that utilization of the payment device for the payment transaction is less burdensome for the user, thereby encouraging use of the payment device for payments. Indeed, in some cases, such as when the payment device is implemented as a finger ring or other type of jewelry, the user may be encouraged to carry the payment device in an exposed manner such that it is readily available for the payment transaction without the user having to search in a wallet, pocket, or purse.

A method includes receiving, by a radio frequency identification (RFID) tag, a radio frequency (RF) signal from an RFID reader. When the RF signal includes a command, the method further includes interpreting, by the RFID tag, the command to determine a field strength shell of interest. When the RFID tag is in the field strength shell of interest, the method further includes further interpreting, by the RFID tag, the command to determine a type of request, and providing, by the RFID tag, a response regarding the type of request to include one or more of a matched impedance value generated in response to the RF signal, a field strength reference current generated in response to the RF signal, and a digital value representative of an environmental condition.

The transponder comprises an antenna and a receiver circuit (2) for receiving RF signals, this receiver circuit is implemented with a control mechanism to activate it at least periodically in a listening mode. This receiver circuit is comprises a decoding circuit (4), formed at least by a demodulator (8) and a decoder (10), and a wake-up circuit (14B) to analyze received RF signals in the listening mode and arranged for controlling the activation of the decoding circuit in this listening mode. The wake-up circuit comprises a frequency discriminator (17) and a digital modulation or preamble detector (18) downstream from a field clock generator (28). The wake-up circuit receives as entry an alternating signal branched from the signal chain through the receiver circuit upstream from the demodulator and it activates the decoding circuit only when a modulation or a preamble is detected in a received RF signal by the digital modulation or preamble detector.

According to the embodiments described herein, a stretchable RFID device can include an RFID chip and an RFID antenna. The RFID antenna can be electrically coupled and mechanically attached to the RFID chip. The RFID antenna can be impedance matched to the RFID chip across a broad bandwidth and can include two arms. Each of the two arms can include an end-loading body that at least partially surrounds an end-loading orifice. The end-loading body can stretch without consuming the end-loading orifice.