Abstract: A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

Abstract: Systems and methods for radio-frequency identification (RFID) tag communication are provided. One radio-frequency identification (RFID) tag includes a communication device configured to communicate with an RFID reader and an impedance element configured to change an variable impedance of the RFID tag. The RFID tag further includes at least one switch connected to the impedance element and a controller connected to the at least one switch and configured to control operation of the switch between open and closed states based on a control signal received from the RFID reader, wherein the variable impedance of the RFID tag is changed between a first modulating impedance value and a second modulating impedance value when the switch is changed between the open and closed states.

Abstract: Systems and methods for radio-frequency identification (RFID) tag communication are provided. One radio-frequency identification (RFID) tag includes a communication device configured to communicate with an RFID reader and an impedance element configured to change an variable impedance of the RFID tag. The RFID tag further includes at least one switch connected to the impedance element and a controller connected to the at least one switch and configured to control operation of the switch between open and closed states based on a control signal received from the RFID reader, wherein the variable impedance of the RFID tag is changed between a first modulating impedance value and a second modulating impedance value when the switch is changed between the open and closed states.

Abstract: Systems and methods for antenna pattern measurement are provided. One system includes a plurality of wireless sensors arranged in an array, wherein the wireless sensors are configured to be powered by radio-frequency (RF) signals at different power levels. The system also may include a controller configured to wirelessly transmit the RF signals at different power levels and measure responses from the wireless sensors at the different power levels. The system may further include a processor configured to calculate a radiation pattern of an antenna under test using the measured responses.

Abstract: Systems and methods for a distributed antenna network are provided. One system includes a plurality of antenna modules coupled via a communication line, with each antenna module configured to be switched between a through state and a connected state using radio-frequency identification (RFID) control signals. The system further includes a plurality of antennas, with each antenna connected to a corresponding antenna module. A controller is coupled to the communication line and configured to transmit RFID control signals to the plurality of antenna modules to selectively activate one of the antenna modules by switching the antenna module to the connected state to thereby activate an antenna connected to the antenna module in the connected state.

Abstract: A system and method for powering and communicating with wireless sensors are provided. One system includes a radio-frequency (RF) transmitter configured to transmit at least one of RF power signals or RF communication signals and a coupling circuit configured to couple the RF transmitter to electrical wiring to allow transmission of the RF power signals or the RF communication signals through the electrical wiring. The system also includes a connector configured to couple the RF transmitter to a power outlet of the electrical wiring.

Abstract: Passive wireless transponders can perform transponder-to-transponder communication when illuminated by an interrogation carrier wave. The transponder-to-transponder communication permits each transponder to determine the identity of “other” proximately transponders. The transponder-to-transponder communication optionally permits each transponder to identify a “nearest neighbor” using one or more backscatter signal properties such as received signal strength or time-of-flight. Using this information and one or more externally supplied or internally stored instruction sets transponders can provide neighboring transponder data to an interrogator. Using this “neighbor” data, the interrogator can provide a system user with data indicative of the relative locations of a plurality of tags arranged in a one or two dimensional matrix.

Abstract: Provided are RFID systems, methods and RFID tags according to various aspects. An infrared (IR) beam, from an IR transmitter, is outputted in a first direction so that an RFID tag with an IR sensor adds a flag to stored data in the RFID tag in response to the RFID tag's IR sensor detecting the IR beam. An RF interrogation signal is outputted by an RFID reader, and a response is received from the RFID tag to the RF interrogation signal. It is determined whether the flag is contained in the RFID tag's response to the RF interrogation signal, and if so, the RFID tag is determined to be in the first direction relative to the IR transmitter.

Abstract: A system, method and computer readable medium are provided. One system includes a transmit antenna, at least one receive antenna, and an imager configured to acquire one or more images in a scanning area having one or more radio frequency identifier (RFID) tags including an RFID tag of interest. The system further includes a controller configured to operate the transmit antenna and the at least one receive antenna to acquire location information from the RFID tags, wherein the controller is further configured to operate the imager to acquire the images while the location information is acquired. The system includes a processor configured to correlate the acquired location information and the one or more images to determine an image corresponding to a location of the RFID tag of interest. The system additionally includes a display configured to display the image corresponding to the location of the RFID tag of interest.

Abstract: A distance between at least one antenna of an interrogation system and a transponder, such as an RFID tag, is determined based on derivatives with respect to frequency of the phase and the signal strength of responses transmitted by the transponder and received at the at least one antenna. The derivatives of the phase and the signal strength facilitate compensating for sources of multipath interference. Determining changes in distance may further facilitate determining location, speed, or bearing of the transponder by the interrogation system.

Abstract: A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

Abstract: A system for determining a bearing or location of a radio frequency identification (RFID) tag using a handheld RFID reader is described. In one embodiment, the reader is equipped with an accelerometer. A user moves the reader while the reader receives the tag's signal and determines the tag signal's phase at multiple locations. The locations of the reader antenna can be reconstructed using the accelerometer data. By using the phase determined at multiple locations in conjunction with the location of the reader antenna, the reader can determine the bearing of the tag. For an RFID reader not equipped with an accelerometer, the sign and ratio of the rate of change in the phase of a tag's signal to the distance traveled by the reader antenna can be used to determine the location of the tag relative to the reader.

Abstract: A reconfigurable antenna element is controlled using a wirelessly powered and wirelessly activated switch, where the antenna element is part of an antenna or antenna array. A control signal for reconfiguring the antenna element is embedded into a wirelessly transmitted data signal for transmission by the antenna.

Abstract: Systems and methods for authentication are provided. One system includes a device configured to sense electrical characteristics of an item coupled with a person and a memory storing a plurality of electrical signatures corresponding to measured electrical characteristics for a plurality of items. The system also includes a controller operable on a processor to determine if an electrical signature determined from sensed electrical characteristics of the item coupled with the person match one of the plurality of electrical signatures stored in the memory to authenticate the person having the item coupled thereto.

Abstract: Provided are RFID systems, methods and RFID tags according to various aspects. An infrared (IR) beam, from an IR transmitter, is outputted in a first direction so that an RFID tag with an IR sensor adds a flag to stored data in the RFID tag in response to the RFID tag's IR sensor detecting the IR beam. An RF interrogation signal is outputted by an RFID reader, and a response is received from the RFID tag to the RF interrogation signal. It is determined whether the flag is contained in the RFID tag's response to the RF interrogation signal, and if so, the RFID tag is determined to be in the first direction relative to the IR transmitter.

Abstract: A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

Abstract: A trickle-charged RFID device includes a main antenna receiving wireless interrogator signals from one or more RFID readers, a power harvester connected with the main antenna to obtain power from the wireless interrogator signals, and an intermediate storage device connected to the power harvester to collect trickle flows of unused power harvested from wireless interrogator signals received by the RFID device that lack an inquiry for the device. The RFID device further includes a primary storage device, into which the intermediate storage device discharges its collection of trickle flows of unused power when the collection reaches a predetermined threshold level, which recharges power lost from the main storage device. The intermediate storage device can include one or more capacitors including super-capacitors, and the main storage device can include a rechargeable battery, such that the effective life of the main storage device is extended from the collected trickle flows.

Abstract: A passive, self-steering antenna device is provided along with methods pertaining to operations and controls of the antenna device. The antenna device can include a main antenna for receiving an unmodulated wireless signal, a power harvester configured to obtain power from the unmodulated wireless signal, a main circuit disposed in a central region of the antenna device, and a plurality of peripheral distributed antenna elements configured to modify the radiation pattern of the antenna device. The antenna device can be configured to operate automatically device without needing control information in response to receiving a message from another antenna. Related methods include operations and controls for such an antenna device including automatically performing actions to enhance communications with another antenna device by selecting and activating a subset of the peripheral antenna elements to create a radiation pattern.

Abstract: A passive, self-reconfigurable antenna device, components of a corresponding wireless network, and methods pertaining to operations and controls of the antenna device are provided. The antenna device can include at least one antenna element configured to receive a modulated or unmodulated wireless signal, a power harvester configured to obtain power from the modulated or unmodulated wireless signal, and a first switch coupled to the power harvester and powered by the obtained power from the power harvester. The first switch can be configured to operate automatically when receiving the obtained power without requiring the receipt of control information. Further, the first switch can be configured to automatically operate according to one or more predetermined operating patterns when receiving the obtained power to modulate the corresponding antenna element. This way, antenna operating frequency, or radiation pattern or polarization states can be reconfigured.

Abstract: A reconfigurable antenna element is controlled using a wirelessly powered and wirelessly activated switch, where the antenna element is part of an antenna or antenna array. A control signal for reconfiguring the antenna element is embedded into a wirelessly transmitted data signal for transmission by the antenna.