Extended range passive wireless tag system and method
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsPatrick W. Fink, Timothy F. Kennedy, Gregory Y. Lin
Life of this patent
Estimating the term…
Abstract
A passive wireless tag assembly comprises a plurality of antennas and transmission lines interconnected with circuitry and constructed and arranged in a Van Atta array or configuration to reflect an interrogator signal in the direction from whence it came. The circuitry may comprise at least one surface acoustic wave (SAW)-based circuit that functions as a signal reflector and is operatively connected with an information circuit. In another embodiment, at least one delay circuit and/or at least one passive modulation circuit(s) are utilized. In yet another embodiment, antennas connected to SAW-based devices are mounted to at least one of the orthogonal surfaces of a corner reflector.
Claims27
A passive wireless tag assembly responsive to a wireless interrogator signal from an interrogator by reflecting a return signal derived from the wireless interrogator signal, the return signal containing information added by said passive wireless tag assembly, said passive wireless tag assembly comprising:
- at least one SAW circuit operable for receiving the wireless interrogator signal as an incoming electromagnetic wave, transforming the electromagnetic wave into a surface acoustic wave, and then transforming the surface acoustic wave back into a subsequent outgoing electromagnetic wave serving as the return signal;
- an information circuit constructed and arranged to add information to at least one of the surface acoustic wave, the incoming electromagnetic wave, and the subsequent outgoing electromagnetic wave;
- and
- at least one pair of antennas, each pair connected in a Van Atta array by transmission lines with one another and with said at least one SAW circuit and said information circuit and being constructed and arranged to receive the wireless interrogator signal and transmit the return signal in a direction from whence the wireless interrogator signal came.
A method for increasing the signal range of response for a passive wireless tag assembly responding passively to a wireless interrogator signal from an interrogator, said method comprising:
- receiving the wireless interrogator signal as an incoming electromagnetic wave;
- transforming the incoming electromagnetic wave into a surface acoustic wave;
- adding information to the surface acoustic wave;
- transforming the surface acoustic wave with added information into a subsequent reflected electromagnetic wave;
- and
- creating a time reversal of the incoming electromagnetic signal such that the subsequent reflected electromagnetic wave transmits predominantly in a direction from whence the interrogator signal came.
A passive wireless tag assembly responsive to a wireless interrogator signal from an interrogator by reflecting a return signal derived from the wireless interrogator signal, the return signal containing information added by said passive wireless tag assembly, said passive wireless tag assembly comprising:
- at least one pair of matched SAW circuits, each SAW circuit being operable for receiving an incoming electromagnetic wave, transforming the incoming electromagnetic wave into a surface acoustic wave, and then transforming the surface acoustic wave into a subsequent outgoing electromagnetic wave;
- at least one hybrid coupler connected to said at least one pair of matched SAW circuits;
- and
- at least one pair of antennas, each pair of antennas operatively interconnected with a corresponding one of said at least one pair of matched SAW circuits and said at least one hybrid coupler, each pair of antennas being constructed and arranged to receive the wireless interrogator signal and create a time reversal of the incoming electromagnetic wave corresponding to the wireless interrogator signal such that the subsequent outgoing electromagnetic wave transmits predominantly in a direction from whence the interrogator signal came.
A passive wireless radio frequency identification tag system comprising:
- an interrogator operable to produce a wireless interrogator signal;
- and
- a passive wireless tag assembly comprising,
- at least one delay circuit operable for delaying an electromagnetic wave entering said at least one delay circuit by a predetermined time delay τ;
- at least one frequency responsive circuit comprising a transfer function that is a function of frequency, and wherein said circuit is operable for adding information to said wireless interrogator signal, said information being derived from said transfer function;
- and
- at least one pair of antennas, each pair of antennas being operatively connected with a corresponding one of said at least one delay circuit and one of said at least one frequency responsive circuit, and each antenna being configured to receive the wireless interrogator signal, create a time reversal of the incoming electromagnetic wave such that the subsequent outgoing return signal transmits predominantly in a direction from whence said interrogator signal came.
A passive wireless tag system comprising:
- an interrogator comprising a pulse generator and at least one first filter, said interrogator being operable to produce a wireless interrogator signal;
- and
- a passive wireless tag assembly comprising,
- at least one second filter, wherein said wireless interrogator signal is a complex conjugate to said second filter such that correlation is achieved at the passive wireless tag assembly;
- and
- a plurality of antennas and transmission lines interconnected with said at least one second filter and being configured to receive said wireless interrogator signal and transmit a return signal predominantly in a direction from whence said interrogator signal came.
Dependencies are inferred from the claim text.