Method and apparatus for improving the interrogation range of an RF-Tag
First Claim
1. A method of increasing an interrogation range in an RF-Tag monitoring system having an Interrogator and a plurality of reflecting antenna elements for receiving RF signals of a wavelength (λ
- ) and a time period T from the Interrogator and reflecting back to the Interrogator modulated signals, wherein said plurality of reflecting antenna elements are spatially positioned along a path of activation, said method comprising the step of;
activating at least some of the reflecting antenna elements in said plurality along said path of activation for a duration of time so that a presently activated reflecting antenna element is positioned farther along the path of activation with respect to a previously activated reflecting antenna element.
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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 multiple reflecting antenna elements. The reflecting antenna elements are predeterminately positioned, and preferably aligned, with respect to each other in the direction of expected incident RF radiation. The reflecting antenna elements are sequentially pulsed on and off such that while the first reflecting antenna element is in a signal reflecting operating state, the remaining reflecting antenna elements are in a substantially non-reflecting state, and when the second reflecting element is in a reflecting operating state, the remaining reflecting elements are in a non-reflecting state, etc. The sequential pulsing and predetermined fixed spacing between the reflector elements generates constructive interference between the reflected signals of the reflecting antenna elements which increases the power of the resulting reflected signal.
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Citations
27 Claims
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1. A method of increasing an interrogation range in an RF-Tag monitoring system having an Interrogator and a plurality of reflecting antenna elements for receiving RF signals of a wavelength (λ
- ) and a time period T from the Interrogator and reflecting back to the Interrogator modulated signals, wherein said plurality of reflecting antenna elements are spatially positioned along a path of activation, said method comprising the step of;
activating at least some of the reflecting antenna elements in said plurality along said path of activation for a duration of time so that a presently activated reflecting antenna element is positioned farther along the path of activation with respect to a previously activated reflecting antenna element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- ) and a time period T from the Interrogator and reflecting back to the Interrogator modulated signals, wherein said plurality of reflecting antenna elements are spatially positioned along a path of activation, said method comprising the step of;
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11. 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 plurality of reflecting elements for receiving RF signals of a wavelength (λ
- ) and a time period T and for reflecting modulated signals derived from the received RF signals, wherein said plurality of reflecting elements are positioned along a path of activation, said method comprising the step of;
activating at least some of the reflecting elements in the plurality along said path of activation for a duration of time so that a presently activated antenna element is positioned farther along the path of activation with respect to a previously activated reflecting antenna element. - View Dependent Claims (12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26)
- ) and a time period T and for reflecting modulated signals derived from the received RF signals, wherein said plurality of reflecting elements are positioned along a path of activation, said method comprising the step of;
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13. An RF Tag communication system, comprising:
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an Interrogator for transmitting RF signals having a carrier wavelength (λ
) and a period (T);
a plurality of reflecting antenna elements for receiving RF signals of the wavelength (λ
) and the time period T from the Interrogator and reflecting back to the Interrogator modulated signals, said plurality of reflecting antenna elements being spatially positioned along a path of activation; and
means for activating at least some of the reflecting antenna elements in said plurality along said path of activation for a duration of time so that a presently activated reflecting antenna element is positioned farther along the path of activation with respect to a previously activated reflecting antenna element.
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23. A reflective communicator for receiving a signal from an Interrogator and reflecting the received signal back to the Interrogator, comprising:
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a plurality of reflective antenna elements disposed along a direction of activation; and
means for activating at least some of the reflective antenna elements in said plurality along said path of activation so that a presently activated reflecting antenna element is positioned farther along the path of activation with respect to a previously activated reflecting antenna element.
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27. A method of compensating for misalignment between an interrogation signal produced by an interrogator and a reflecting element array comprising a plurality of reflecting antenna elements by activating selected numbers of the plural reflecting antenna elements during a series of predetermined activation time periods T, comprising the steps of:
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(a) activating a selected number of the plural reflecting antenna elements during an activation time period T to receive and reflect the interrogation signal back to the interrogator;
(b) measuring the strength of the reflected interrogation signal from step (a);
(c) repeating each of steps (a) and (b) for subsequent activation time periods T using different selected numbers of the plural antenna elements; and
(d) using the measured strengths of the reflected interrogation signals from said repeated steps (b) to determined a desired number of the plural antenna elements to be activated to produce a desired strength reflected signal.
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Specification