Method and apparatus for improving the interrogation range of an RF tag
First Claim
1. A method for increasing an interrogation range in an RF Tag monitoring system comprising an Interrogator and a first reflecting antenna element and a second reflecting antenna element for receiving RF signals from the Interrogator and reflecting back to the Interrogator modulated signals, wherein the second reflecting antenna element is fixedly positioned and spaced with respect to the first reflecting antenna element along a direction of expected receipt of the RF signals from the Interrogator, the method comprising the step of:
- alternately pulsing the first and second reflecting antenna elements on and off such that while the first reflecting antenna element is in a reflecting mode the second reflecting antenna element is in a non-reflecting mode, and when the first reflecting antenna element is in the non-reflecting mode the second reflecting antenna element is in the reflecting mode.
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Accused Products
Abstract
A method for increasing the interrogation range of an RF Tag in a radio communication system using RF Tags with two reflecting antenna elements. The second reflecting antenna element is predeterminately positioned, and preferably aligned, with respect to the first reflecting antenna element in the direction of expected incident RF radiation and is spaced from the first reflecting antenna element at a predetermined fixed distance. The first and second reflecting antenna elements are alternately pulsed on and off such that while the first reflecting antenna element is in a signal reflecting operating state, the second reflecting antenna element is in a substantially non-reflecting state and vice versa. The alternate pulsing and predetermined fixed spacing between the first and second elements generates a known phase difference between the reflected signals of the first and second reflecting antenna elements. The phase difference is preferably 180 degrees which may be achieved by spacing the second reflecting antenna element from the first reflecting antenna element at a distance equivalent to ¼ of the wavelength of the interrogating signals.
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Citations
31 Claims
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1. A method for increasing an interrogation range in an RF Tag monitoring system comprising an Interrogator and a first reflecting antenna element and a second reflecting antenna element for receiving RF signals from the Interrogator and reflecting back to the Interrogator modulated signals, wherein the second reflecting antenna element is fixedly positioned and spaced with respect to the first reflecting antenna element along a direction of expected receipt of the RF signals from the Interrogator, the method comprising the step of:
alternately pulsing the first and second reflecting antenna elements on and off such that while the first reflecting antenna element is in a reflecting mode the second reflecting antenna element is in a non-reflecting mode, and when the first reflecting antenna element is in the non-reflecting mode the second reflecting antenna element is in the reflecting mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13)
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8. A method for increasing an interrogation range in an RF Tag monitoring system utilizing a Luneberg lens reflector as an RF Tag for receiving and reflecting RF signals, the Luneberg lens having a first and a second set of reflecting elements spaced from a modulating diode array, wherein the second set of reflecting elements is fixedly positioned and spaced with respect to the first set of reflecting elements along a direction of expected incident receipt of the RF signals by the Luneberg lens reflector, the method comprising the step of:
alternately pulsing the first and second sets of reflecting elements on and off such that while the first set of reflecting elements is in a reflecting mode, the second set of reflecting elements is in a non-reflecting mode, and when the first set of reflecting elements is in a non-reflecting mode, the second set of reflecting elements is in a reflecting mode.
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14. An RF Tag communication system, comprising:
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an Interrogator for transmitting RF signals;
a first antenna element and a second antenna element for receiving the RF signals from the Interrogator and for reflecting modulated signals back to the Interrogator, said at first and second antenna elements being fixedly spaced from one another along a direction of expected incident receipt of RF signals. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An RF Tag communication system, comprising:
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an Interrogator for transmitting RF signals;
a first, a second and a third reflecting antenna element for receiving the RF signals from the Interrogator and for reflecting modulated signals back to the Interrogator, and a processor, wherein said first, second and third antenna elements are arranged in a triangular configuration with respect to each other, said Interrogator transmitting an initial RF signal to instruct said processor to alternately pulse said first, second and third reflecting antenna elements on and off in predetermined pairs such that two antenna elements are pulsed on and off for a predetermined interval while the third remains off during the predetermined interval. - View Dependent Claims (26, 27)
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28. An RF Tag communication system, comprising:
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an Interrogator for transmitting RF signals;
a first, a second, a third and a fourth reflecting antenna element for receiving the RF signals from the Interrogator and for reflecting modulated signals back to the Interrogator, and a processor, wherein said antenna elements are arranged in a tetrahedral configuration, said Interrogator transmitting an initial RF signal to instruct said processor to alternately pulse said reflecting antenna elements on and off in predetermined pairs such that two antenna elements are pulsed on and off for a predetermined interval while the other two elements remain off during the predetermined interval. - View Dependent Claims (29, 30)
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31. A method for increasing an interrogation range in an RF Tag monitoring system comprising an Interrogator and a first reflecting antenna element and a second reflecting antenna element for receiving RF signals from the Interrogator and reflecting back to the Interrogator modulated signals, wherein the second reflecting antenna element is fixedly positioned and spaced with respect to the first reflecting antenna element along a direction of expected receipt of the RF signals from the Interrogator, the method comprising the step of:
alternately pulsing both the first and second reflecting antenna elements on and off together such that both reflecting antenna elements are simultaneously either in the reflecting mode or else in the non-reflecting mode.
Specification