Abstract: The present invention is directed to systems that use frequency selective surfaces (FSS) to aid in the operation of radio frequency identification (RFID) devices and products. In one embodiment, a system for interrogating radio frequency identification (RFID) tags includes a conveyor belt and an RFID reader. The conveyor belt has a first surface and a second surface. The first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate. The RFID reader is configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag, wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

Abstract: A method for improving RFID readers includes transmitting an outgoing RF signal to an antenna through a directional device, and generating a demodulated vector signal from an RF signal related to the RF signal received from the receiver. The method also includes setting the impedance of a controllable-variable-reflectance element with control-parameters from a memory circuit. The memory circuit includes a look up table having therein a corresponding relationship between the control-parameters and an error vector related to the demodulated vector signal.

Abstract: Methods, systems, and apparatuses for a reader transceiver circuit are described. The reader transceiver circuit incorporates a frequency generator, such as a surface acoustic wave (SAW) oscillator. A reader incorporating the reader transceiver circuit is configured to read a tag at very close range, including while being in contact with the tag. The transceiver can be coupled to various host devices in a variety of ways, including being located in a RFID reader (e.g., mobile or fixed position), a computing device, a barcode reader, etc. The transceiver can be located in an RFID module that is attachable to a host device, can be configured in the host device, or can be configured to communicate with the host device over a distance. The RFID module may include one or more antennas, such as a first antenna configured to receive a magnetic field component of an electromagnetic wave and a second antenna configured to receive an electric field component of an electromagnetic wave.

Abstract: Methods, systems, and apparatuses for a reader transceiver circuit are described. The reader transceiver circuit incorporates a frequency generator, such as a surface acoustic wave (SAW) oscillator. A reader incorporating the reader transceiver circuit is configured to read a tag at very close range, including while being in contact with the tag. The transceiver can be coupled to various host devices in a variety of ways, including being located in a RFID reader (e.g., mobile or fixed position), a computing device, a barcode reader, etc. The transceiver can be located in an RFID module that is attachable to a host device, can be configured in the host device, or can be configured to communicate with the host device over a distance. The RFID module may include one or more antennas, such as a first antenna configured to receive a magnetic field component of an electromagnetic wave and a second antenna configured to receive an electric field component of an electromagnetic wave.

Abstract: Methods, systems, and apparatuses for RFID devices, such as reader antennas, are described. A reader antenna includes a quadrature hybrid coupler, a termination element, and an antenna, such as a patch antenna. The quadrature hybrid coupler has first, second, third, and fourth ports. The first port receives an input radio frequency RF signal. The second port outputs a first RF output signal. The third port outputs a second RF output signal. The second RF output signal is shifted in phase by 90 degrees relative to the first RF output signal. The fourth port is coupled to the termination element. The patch antenna has a first point coupled to the first RF output signal and a second point coupled to the second RF output signal. The patch antenna radiates a circularly polarized RF signal due to the received first and second RF output signals. The circularly polarized RF signal may be used to interrogate tags.

Abstract: Due to design constraints and installation variability, RFID interrogator antennas do not always function optimally across the entire channel on which they are intended to operate due to diminished antenna bandwidth. Techniques are described for selecting a sub-band of frequencies within the channel on which a particular RFID interrogator can be operated to enhance operating efficiency. These techniques include a VSWR measurement technique and a read/no read technique are disclosed for identifying a useful sub-band of frequencies. The operation of a reader/interrogator is then limited to an identified sub-band so that an RFID interrogator/tag system can be operated efficiently.

Abstract: Methods, systems, and apparatuses for radio frequency identification (RFID) readers are described. In as aspect, a reader antenna includes an attaching element, a radome with an attached director element and a radiating element. The radiating element is positioned coupled to a surface of the attaching element. The radiating element transmits a RF signal for the reader antenna. The director element attached to the radome element focuses the RF signal to alter a characteristic of the RF signal transmitted by the reader antenna.

Abstract: Methods, systems, and apparatuses for manufacturing light weight microstrip element antennas incorporating a skeleton dielectric spacer instead of a regular solid body dielectric spacer is described. The microstrip element antenna comprises a radiator, a dielectric layer which is in the form of a skeleton rib-caged structure and a ground plane layer. Due to the skeleton rib-caged structure of the dielectric spacer, design flexibility in terms of a non-uniform variation of the effective dielectric constant across various dimensions of the dielectric layer is obtained. Additional advantages of such a dielectric spacer include a wider choice of materials from which the antenna can be made, overall light weight and low production time and machine cost due to lower cooling time of the dielectric. Further, an antenna with a skeleton dielectric spacer further has a better drying characteristics in an event of a water ingress during or post-production.

Abstract: Methods, systems, and apparatuses for radio frequency identification (RFID) reader antennas are described. In as aspect, a reader antenna includes a reflecting element and a radiating element. The reflecting element has a body that defines a cavity. The radiating element is positioned in the cavity. The radiating element transmits a RF signal for the reader antenna. The reflecting element reflects the RF signal to alter a characteristic of the RF signal transmitted by the reader antenna.

Abstract: A portable/handheld device is provided having a processing module configured to selectively operate a reading mode selected from a far-field mode and a near-field mode, and a directional antenna array coupled to the processing module. The directional antenna array includes a first antenna element configured to radiate electromagnetic (EM) radiation in a far-field, and a second antenna element coupled to the first antenna element. The second antenna element is configured to radiate EM radiation in a near-field. The second antenna element includes an antenna transducer configured to selectively cancel far-field EM radiation from the first antenna element. A method of reading inductively coupled radio frequency identification (RFID) tags is also provided having the steps of scanning at least one frequency band to detect a RFID tag, and selectively radiating one of a near-field electromagnetic (EM) field and a far-field EM field based on the detected RFID tag.

Abstract: The present invention is directed to systems that use frequency selective surfaces (FSS) to aid in the operation of radio frequency identification (RFID) devices and products. In one embodiment, a system for interrogating radio frequency identification (RFID) tags includes a conveyor belt and an RFID reader. The conveyor belt has a first surface and a second surface. The first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate. The RFID reader is configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag, wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

Abstract: Methods, systems, and apparatuses for a reader transceiver circuit are described. The reader transceiver circuit incorporates a frequency generator, such as a surface acoustic wave (SAW) oscillator. A reader incorporating the reader transceiver circuit is configured to read a tag at very close range, including while being in contact with the tag. The transceiver can be coupled to various host devices in a variety of ways, including being located in a RFID reader (e.g., mobile or fixed position), a computing device, a barcode reader, etc. The transceiver can be located in an RFID module that is attachable to a host device, can be configured in the host device, or can be configured to communicate with the host device over a distance. The RFID module may include one or more antennas, such as a first antenna configured to receive a magnetic field component of an electromagnetic wave and a second antenna configured to receive an electric field component of an electromagnetic wave.

Abstract: Methods and apparatus are provided for mode diversity radio frequency identification (RFAID). The apparatus comprises a first transducer configured to receive a first radio frequency (RF) signal, a second transducer configured to receive an acoustic signal, and an impedance modulator coupled to the first transducer and the second transducer and configured to emit a signal identifying an RFAID tag when the first transducer receives the first RF signal and/or the second transducer receives the acoustic signal. The method comprises transmitting an RF signal and an acoustic frequency signal, and detecting a first modulated signal indicating an RFAID transponder. The first modulated signal is based on one of the RF signal and the acoustic signal.

Abstract: A directional antenna array is provided that includes a driven element and a first parasitic element separated from the driven element with the first parasitic element and/or the driven element having a width that is greater than about one-half a percent (0.5%) of an free-space wavelength of the directional antenna array. Alternatively or in conjunction, the directional antenna array includes a balun structure that is configured to couple the driven element to at least one of an electromagnetic energy source and an electromagnetic sink, and the balun structure includes a dipole structure, a first feed point extending from the dipole structure and a second feed point extending from the first parasitic element.

Abstract: An object location system and method is provided for locating objects. The system includes an RFID reader, an angle calculator, and a distance calculator to determine which of a plurality of zones an object is located in or passing through. An RFID tag is affixed with the object that is to be located. The RFID reader transmits signals to the RFID tag and receives backscatter-modulated signals from the RFID tag at one or more RFID antennas. From those received signals, the angle calculator determines an angle of position of the RFID tag relative to the RFID antenna. From the angle of position the zone in which the object is located is determined.

Abstract: An RFID relay device for an RFID transponder and methods are provided for relaying an RFID signal. The RFID relay device comprises at least two antenna and a transmission line coupling the at least two antenna. In addition to the two antenna and the transmission line, the RFID relay device comprises an impedance adjusting circuit coupled to the transmission line and configured for coupling to the RFID transponder.

Abstract: An RFID relay device for an RFID transponder and methods are provided for relaying an RFID signal. The RFID relay device comprises at least two antenna and a transmission line coupling the at least two antenna. In addition to the two antenna and the transmission line, the RFID relay device comprises an impedance adjusting circuit coupled to the transmission line and configured for coupling to the RFID transponder.

Abstract: A detector for detecting radiant energy includes at least one detecting element and a detector readout element. The at least one detecting element substantially absorbs the radiant energy and exhibits a structural change in response thereto. The detector readout element, positioned in non-contacting proximity to the at least one detecting element, is responsive to the structural change of the at least one detecting element. The non-contacting detector readout element provides an indication signal corresponding to the structural change, whereby the corresponding indication signal is representative of the radiant energy detected by the at least one detecting element.

Abstract: A detector for detecting radiant energy includes at least detecting element and a detector readout element. The at least one detecting element substantially absorbs the radiant energy and exhibits a structural change in response thereto. The detector readout element, positioned in non-contacting proximity to the at least one detecting element, is responsive to the structural change of the at least one detecting element. The non-contacting detector readout element provides an indication signal corresponding to the structural change, whereby the corresponding indication signal is representative of the radiant energy detected by the at least one detecting element.