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.
2 Assignments
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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
26 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 with a radio frequency identification (RFID) tag, the interrogator comprising:
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an antenna; a radio frequency transmitter communicatively coupled to the antenna and configured to transmit commands at a first radio frequency band, a first command and a second command including a selection indicator, the selection indicator identifying one or more of a plurality of possible RFID tags; a radio frequency receiver communicatively coupled to the antenna and configured to receive one or more responses from a selected RFID tag at a second radio frequency band, the second radio frequency band being different than the first radio frequency band, at least one of the responses including a random number generated by the selected RFID tag, the selected RFID tag being identified at least in part by the selection indicator; and a processor communicatively coupled to the radio frequency receiver and the radio frequency transmitter and configured to format commands and process responses to identify RFID tags, the processor using the random number to identify the selected RFID tag in at least one subsequent command. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification