A system is described for maintaining an inductive-capacitive (LC) network at resonance while the excitation frequency may be varied between a number of discrete frequencies at desired instants controlled by a modulation input, while taking into account component parameter errors due environmental and ageing as well as manufacturing tolerances. Control of the resonance while the excitation frequency changes permits the transmission of frequency modulation (FM) or frequency shift keying (FSK) information through an inductively coupled power transfer system.

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 wireless sensor includes a radio frequency (RF) receiving circuit including a plurality of components, where impedances of the plurality of components establish a resonant frequency of the RF receiving circuit. The wireless sensor further includes a sensing element that when exposed to an environmental condition, affects the resonant frequency of the RF receiving circuit. The wireless sensor further includes a processing module that is operable to determine a first value for an adjustable element of a plurality of elements for a known environmental condition based on the resonant frequency and the carrier frequency, determine a second value for the adjustable element for an unknown environmental condition based on the resonant frequency and the carrier frequency, and determine a difference between the first and second values that corresponds to a change between the known environmental condition and the unknown environmental condition.

A NFC object reader's NFC antenna system configured to dynamically change an element of the NFC antenna system to maintain the NFC antenna system's antenna default resonant frequency. The NFC antenna system can be configured to include a tuning subsystem, integrated with sensors to trigger tuning of NFC antenna system's antenna.

A method includes receiving a series of radio frequency (RF) signals, where, from RF signal to RF signal of the series of RF signals, a carrier frequency is changed in accordance with a frequency hopping pattern. The method further includes, while receiving the series of RF signals, sensing an environmental condition by, for a frequency hop of at least some frequency hops of the frequency hopping pattern, adjusting a characteristic of a wireless sensor to maintain proximal alignment of a resonant frequency of the wireless sensor with the carrier frequency corresponding to a present frequency of the at least some frequency hops and generating a value to represent the adjustment of the characteristic, where a set of values is generated for the at least some frequency hops and where the set of values is used to determine a sensed value of the environmental condition.

An RFID system in which at least one of the RFID tag antenna and the RFID reader antenna has an impedance matching network associated therewith in order to better match the impedances of the two antennas. This impedance matching places the antennas into an over-coupled regime once they are within a reasonable distance of each other (e.g., 2 to 50 mm). It also increases the Q-factor of the improved antenna, which can greatly increase the range at which the RFID reader can read the RFID tag. This improved RFID system may be used in any of a variety of application, including operating a door lock mechanism.

Methods and systems are provided for an RFID system that can be tuned dynamically and/or in real-time during a coupling event between a reader and a transponder. The reader can comprise an antenna assembly, a signal driver, and a controller. The antenna assembly may include a tuning circuit and an antenna coupled to the tuning circuit. The tuning circuit can include registers that may be set to adjust one or more characteristics of the reader. A controller is coupled to the antenna assembly to determine characteristics of the received signal and to set hardware or firmware functions that improve the coupling of the reader and transponder and/or improve the reception of the signal(s) from the transponder.

A wireless tag processing device includes a wireless tag reader-writer and a processor configured to acquire first and second sets of parameter values, control the reader-writer to transmit a radio wave using each parameter value of the first set and acquire a first intensity of a response wave from a wireless tag, when a highest first intensity satisfies a first condition, determine a parameter value of the first set corresponding to the highest intensity as a parameter value to be used by the reader-writer, and when the highest intensity does not satisfy the condition, control the reader-writer to transmit a radio wave using each parameter value of the second set and acquire a second intensity, and when a highest second intensity satisfies a second condition, determine a parameter value of the second set corresponding to the highest second intensity as the parameter value to be used by the reader-writer.

A method includes receiving, by an RF receiving circuit of a passive wireless sensor of a wireless communication system, an RF signal. When a sensing element of the passive wireless sensor is exposed to an environmental condition, the method further includes affecting, by the sensing element, resonant frequency of the RF receiving circuit. The method further includes determining, by a processing module of the passive wireless sensor, a first value for an adjustable element for a known environmental condition, determining a second value for the adjustable element for an unknown environmental condition, determining a difference between the first and second values that correspond to a change, generating a coded value representative of the change, and transmitting the coded value. The method further includes receiving, by a second processing module of a sensor computing device of the wireless communication system, the coded value and determining a sensed environmental condition.

A resonant structure includes a conductive surface layer on a dielectric layer that produces an enhanced or reduced backscattered radiation in one or more resonant frequency bands when illuminated with electromagnetic energy. A transmitter illuminates the resonant structure with the electromagnetic energy at a first angle relative to the normal of the conductive surface. A receiver is operable to detect the enhanced or reduced backscattered radiation at the resonant frequency bands at a second angle relative to the normal of the conductive surface. The second angle is different from the first angle by at least five degrees. A processor coupled to the receiver and is operable to detect data encoded in one or both of a frequency response and a polarization response of the resonant structure based on the detected enhanced or reduced backscattered radiation.