Method and apparatus for RFID communication
First Claim
1. A method of testing the RF communication operation of an RF transponder, comprising the steps of:
- providing a sheet characterized by first and second opposite faces and a thickness;
mounting on the sheet an RF transponder that includes a transponder RF antenna;
positioning a first RF shield so as to abut the first face of the sheet;
positioning a second RF shield so as to abut the second face of the sheet, the second RF shield being in the shape of a cup having a mouth abutting said second face, wherein the first and second RF shields are positioned so that the first and second RF shields together form a closed cavity which completely surrounds and encloses the transponder RF antenna except where the thickness of the sheet separates the first RF shield from the mouth of the second RF shield, wherein said thickness is sufficiently small so that the first and second RF shields prevent any RF signals within the cavity from radiating outside the cavity;
positioning a test fixture RF antenna within the cavity;
transmitting an RF signal from the test fixture antenna;
detecting a response by the transponder to the RF signal; and
subsequently removing the transponder from proximity to the first and second shields and the test fixture RF antenna, so that no shielding obstructs the transponder RF antenna from sending and receiving RF radiation at any angle.
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Accused Products
Abstract
A plurality of battery-operated transceivers encapsulated by lamination to form a sheet of independent transceivers is tested in a two piece fixture that forms an enclosure surrounding each in-sheet transceiver. Each enclosure has an antenna for transmitting a command signal to the transceiver at a known power level and for receiving a reply message from the transceiver containing a power level measurement made by the transceiver. Test methods using the fixture of the present invention are also described.An RFID tag and interrogator may each include a transmitter and a receiver. The tag and interrogator may communicate with each other at different frequency bands and may communicate in accordance with a wireless communication protocol.
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Citations
29 Claims
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1. A method of testing the RF communication operation of an RF transponder, comprising the steps of:
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providing a sheet characterized by first and second opposite faces and a thickness; mounting on the sheet an RF transponder that includes a transponder RF antenna; positioning a first RF shield so as to abut the first face of the sheet; positioning a second RF shield so as to abut the second face of the sheet, the second RF shield being in the shape of a cup having a mouth abutting said second face, wherein the first and second RF shields are positioned so that the first and second RF shields together form a closed cavity which completely surrounds and encloses the transponder RF antenna except where the thickness of the sheet separates the first RF shield from the mouth of the second RF shield, wherein said thickness is sufficiently small so that the first and second RF shields prevent any RF signals within the cavity from radiating outside the cavity; positioning a test fixture RF antenna within the cavity; transmitting an RF signal from the test fixture antenna; detecting a response by the transponder to the RF signal; and subsequently removing the transponder from proximity to the first and second shields and the test fixture RF antenna, so that no shielding obstructs the transponder RF antenna from sending and receiving RF radiation at any angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of testing the RF communication operation of a plurality of RF transponders, comprising the steps of:
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providing a sheet characterized by first and second opposite faces and a thickness; mounting on the sheet a plurality of RF transponders, wherein each transponder includes a transponder RF antenna; positioning a first test fixture section having a first RF shield so that the first RF shield abuts the first face of the sheet; positioning a second test fixture section so as to abut the second face of the sheet, wherein; the second test fixture section includes a plurality of RF shields, each RF shield in the second test fixture section is in the shape of a cup having a mouth abutting said second face of the sheet, the first and second test fixture sections so that each RF shield in the second test fixture section encircles a corresponding one of the transponder RF antennas so as to form, in combination with the first RF shield, a closed cavity that completely surrounds and encloses said corresponding transponder RF antenna except where the thickness of the sheet separates the first RF shield from the mouth of said RF shield in the second test fixture section, and said thickness is sufficiently small so that the first and second RF shields prevent any RF signals within the cavity from radiating outside the cavity; positioning within each cavity a corresponding test fixture RF antenna; transmitting an RF signal from each test fixture antenna; detecting a response by each transponder to the RF signal transmitted by its corresponding test fixture antenna; and subsequently removing each transponder from proximity to the first and second test fixture sections and the test fixture RF antennas, so that no shielding obstructs each transponder RF antenna from sending and receiving RF radiation at any angle. - View Dependent Claims (10, 11)
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12. A test fixture for testing the RF communication operation of an RF transponder which is mounted on a sheet which extends beyond the perimeter of the transponder, the RF transponder having an antenna for receiving RF signals, comprising:
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first and second RF shields, the second RF shield being in the shape of a cup having a mouth; an alignment mechanism for positioning the first and second RF shields to abut opposite sides of the sheet so that the mouth encircles the transponder antenna and so that the combination of the first and second RF shields forms a closed cavity completely surrounding and enclosing the transponder antenna except where the sheet separates the two RF shields, wherein the distance by which the sheet separates the two RF shields is small enough to prevent any RF signals within the cavity from radiating outside the cavity; and a test fixture RF antenna mounted within the cavity. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A test fixture for testing the RF communication operation of a plurality of RF transponders mounted on a sheet, each RF transponder having an RF antenna, comprising:
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a first test fixture section including a first RF shield; a second test fixture section including a plurality of RF shields each of which is in the shape of a cup having a mouth; an alignment mechanism for positioning the first and second test fixture sections to abut opposite sides of the sheet so that each RF shield in the second test fixture section encircles a corresponding one of the transponder antennas so as to form, in combination with the first RF shield, a closed cavity that completely surrounds and encloses said corresponding transponder RF antenna except where the sheet separates the first RF shield from the mouth of said RF shield in the second test fixture section, wherein the distance by which the sheet separates the first RF shield from each RF shield of the second test fixture section is small enough to prevent any RF signals within each cavity from radiating outside that cavity; and a test fixture RF antenna mounted within each cavity. - View Dependent Claims (20)
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21. An interrogator for performing radio frequency communications, the interrogator comprising:
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one or more antennas, a transmitter communicatively coupled to the one or more antennas and configured to transmit one or more messages and RE energy to power a radio frequency identification (RFID) tag; a receiver communicatively coupled to the one or more antennas and configured to receive one or more responses; a processing unit communicatively coupled to the transmitter to transmit a first command to set an inventory flag on the RFID tag to a first state and to transmit a second command to set the inventory flag on the RFID tag to second state, the RFID tag being identified by one or more random numbers received by the processing unit via the receiver and the one or more antennas. - View Dependent Claims (22, 23)
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24. A method of performing radio frequency communications, the method comprising:
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generating by a radio frequency identification (RFID) tag a random number, the random number having a plurality of bits; determining by an interrogator a first radio frequency band to transmit messages to the RFID tag transmitting by the interrogator a first command at the first radio frequency band;
transmitting by the interrogator RF enemy to power the RFID tag;
receiving by the RFID tag the first command at the first radio frequency band;setting an inventoried flag in the RFID tag to a first state, the setting being performed in response to the receiving the first command communicating by the RFID tag a response to the first command at a second radio frequency band; receiving one or more additional commands from the interrogator on the first radio frequency band; and in response to at least one of the additional commands, setting the inventoried flag in the RFID tag to a second state, wherein the first command, the response, and the one or more additional commands include at least a part of one or more random numbers generated by the RFID tag. - View Dependent Claims (25, 26, 27)
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28. A system for performing radio frequency communications, the system comprising:
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one or more antennas; one or more interrogators communicatively coupled to the one or more antennas and configured to transmit a first message and a second message via the one or more antennas; and a radio frequency identification (RFID) tag having a dipole antenna coupled to one or more items to be tracked and configured to set an inventory flag to a first state upon receipt of the first command and to a second state upon receipt of the second command, the first command including at least one random number generated by the RFID tag and the second command including at least one random number generated by the RFID tag. - View Dependent Claims (29)
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Specification