An RF tag for sending data to a tag reader is described. The tag comprises an antenna to couple to an RF field of the tag reader and first and second resonant circuits, the first comprising a non-linear, adaptive resonator configured to automatically self-tune to a frequency of the RF field, the second a linear resonator. The tag also has a local power store. The tag powers up using the non-linear, adaptive resonator, which can automatically self-tune without an external power supply, and this resonator is used to charge the local power store. Once operational the tag switches to using a linear resonator for communicating with the tag reader.

Systems and methods for integrating tags with items. The methods comprise: dynamically determining a length of each metal thread to be incorporated into or trace to be disposed on a item to optimize tag performance in view of dielectric and tuning properties of the item. In the metal thread scenarios, the methods also involve: creating a metal thread having the length that was dynamically determined; and sewing the metal thread into the item being produced to form an antenna for a first tag. In the trace scenarios, the methods also involve forming the trace on the item being produced to form an antenna for a first tag. Next, at least a communications enabled device is attached to the item so as to form an electrical coupling or connection between the communications enabled device and the at least one antenna.

A method for a near-field communication (NFC) tag to perform NFC and wireless power transfer (WPT) with an NFC reader, the NFC tag having an antenna resonant circuit, of which a quality factor (Q-factor) is no lower than 50 in a high-Q mode of the NFC tag, and no higher than 25 in a low-Q mode of the NFC tag. The method includes continuously preforming steps of detecting an NFC radio frequency (RF) field generated by the NFC reader, measuring strength of the NFC RF field, operating in the high-Q mode for the WPT upon determining that the strength of the NFC RF field is larger than a predetermined threshold, operating in the low-Q mode for the NFC upon determining that the strength of the NFC RF field is smaller than the predetermined threshold, and transmitting a response back to the NFC reader.

A device for near-field communication (NFC) and wireless power reception (WPR) using a magnetic field. The device has an antenna resonant circuit. The antenna resonant circuit includes an antenna for magnetic flux of the magnetic field to flow therethrough, to thereby receive a NFC signal during the NFC and receive wireless power during the WPR, and a multi-Q antenna matching circuit configured to adjust an impedance of the antenna to thereby adjust a quality factor (Q-factor) of the antenna resonant circuit. The multi-Q antenna matching circuit is configured to switch between a high-Q mode for the WPR and a low-Q mode for the NFC, based on whether strength of the magnetic field is larger than a predetermined threshold. The device may also include two separate antenna resonant circuits, of which the Q-factors are respectively no higher than 25 and no lower than 50.

Disclosed is an electronic entity having a transponder which includes a body provided with a recess and, inside the recess, a transponder including a mounting supporting an antenna formed by at least one turn running along the contour of the module and a microcircuit, the antenna and microcircuit being connected to one another, plates of conductive material being formed on each of the surfaces facing one another, covering 60-90% of the surface defined by the one or more turns of the antenna, forming a capacitor connected in parallel on the antenna, and the body including an annular metal area, the inner contour of which projects into the plane of the mounting surrounds the mounting and is suitable for concentrating the field lines toward the inside of the turn, the capacitor defining, with the antenna and the microcircuit, a given resonance frequency substantially equal to the frequency of an external reader.

The present invention provides for an RFID transponder, suitable for use in a wristband, which has a non-uniform loop that provides a staple RF environment between the wrist and the transponder; a tuning capacitor for minimizing the overall transponder link; a single transmission line for fine tunings; and an asymmetric location of the RFID IC and capacitor for accommodating needs for specified “keep out” areas for packaging.

An RFID reader, tuning method and computer readable medium. A carrier signal is transmitted. A plurality of feedback signals produced in the RFID reader are measured when transmitting the carrier signal with a variable matching network set at a plurality of impedance values that are different from one another. It is determined which impedance value of the plurality of impedance values produced a feedback signal having a highest level of the plurality of feedback signals. The variable matching network is set to the determined impedance value.

A variable capacitance capacitor element according to an embodiment of the present invention comprises: a supporting substrate; a first electrode layer provided on the supporting substrate; a second electrode layer provided opposite to the first electrode layer; and a dielectric layer positioned between the first electrode layer and the second electrode layer. In accordance with an aspect, a main component of the dielectric layer is represented by a composition formula Ba.sub.1−xSr.sub.xTiO.sub.3 (0.5≦x≦0.8), and the first thin film dielectric layer has a thickness of 200 nm or smaller.

Systems and methods are provided for better reading large populations of RFID tags. Such systems include an RFID reader and a plurality of RFID tags, each having an antenna and an associated RFID chip. Each chip includes an auto-tune circuit and is programmed to confirm the occurrence of a preselected condition. Upon such confirmation, the RFID chip modifies the functionality of the auto-tune circuit to reduce the effects of proximity coupling within the population. The preselected condition may be the tag being read by the RFID reader or the elapse of a preselected amount of time since a power-on-reset of the chip or some other event. The modification to the functionality of the auto-tune circuit may be the disabling of the auto-tune circuit or the changing of the impedance value of the chip or a decrease in the power supplied to the chip or some other modification.

An actively transmitting tag detects a shift of a phase of an antenna signal (as) with regard to a phase of a transmitted signal (ts) in time intervals with a length of one half-period of a subcarrier, in which time intervals it transmits high-frequency wave packets with their phase being inverted according to a communication protocol at the ends of said half-periods. Generation of said wave packets is controlled by said phase shift in a way that said phase shift retains its absolute value at transitions into subsequent half-periods. Synchronizing the tag's transmission to a received interrogator signal carried out even during tag's transmitting enables the tag to transmit according to protocol ISO 14443 B by inverting a phase at transitions between said half-periods. Said synchronizing is carried out although no time window without a tag transmitting exists within the transmitted data frame.