Directional antenna configuration for asset tracking system
First Claim
1. An apparatus for detecting a direction in which a marker is moved through a portal from a first side of the portal to a second side of the portal opposite to the first side, the marker being for transmitting a marker signal, the apparatus comprising:
- first antenna means, located on the first side of the portal, for receiving the marker signal when the marker is on the first side of the portal;
second antenna means, located on the second side of the portal, for receiving the marker signal when the marker is on the second side of the portal; and
detector means, connected to said first and second antenna means, for detecting an order in time in which the marker signal is respectively received by said first and second antenna means.
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Accused Products
Abstract
A directional antenna configuration for use in an article tracking system includes two shorted loops, one on each side of a portal and in each case circumscribing the portal. The antenna configuration also includes a respective pair of passage antennas provided on each side of the portal. The passage antennas are all arranged in planes parallel to the path of travel through the doorway. The respective loops confine the effective detection areas of each pair of passage antennas to the respective side of the portal. The antenna configuration permits reliable detection of direction of movement through the portal.
128 Citations
32 Claims
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1. An apparatus for detecting a direction in which a marker is moved through a portal from a first side of the portal to a second side of the portal opposite to the first side, the marker being for transmitting a marker signal, the apparatus comprising:
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first antenna means, located on the first side of the portal, for receiving the marker signal when the marker is on the first side of the portal; second antenna means, located on the second side of the portal, for receiving the marker signal when the marker is on the second side of the portal; and detector means, connected to said first and second antenna means, for detecting an order in time in which the marker signal is respectively received by said first and second antenna means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In an apparatus for detecting a marker which transmits a marker signal, the apparatus including a first antenna located on the first side of a portal and a second antenna located on a second side of the portal, the second side being accessible by travel through the portal from the first side, a method of detecting a direction in which the marker is moved through the portal, the method comprising the steps of:
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sequentially and repetitively receiving signals from the first and second antennas, respectively; and detecting at which one of the first antenna and the second antenna the marker signal is received first. - View Dependent Claims (15, 16, 17)
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18. An antenna configuration for use with article surveillance apparatus located at a portal, the portal defining a path of travel between a first side of the portal and a second side of the portal, the configuration comprising:
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a first shorted loop which substantially circumscribes the portal and is displaced from the portal towards the first side of the portal; and a second shorted loop which substantially circumscribes the portal and is displaced from the portal towards the second side of the portal. - View Dependent Claims (19, 20, 21, 22, 23)
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24. An apparatus for detecting a direction in which a marker is moved through a portal from a first side of the portal to a second side of the portal opposite to the first side, the marker being for transmitting a marker signal, the apparatus comprising:
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antenna means for receiving the marker signal as the marker is moved through the portal; and confinement means for forming, during a sequence of first time intervals, a first interrogation area substantially confined to the first side of the portal and for forming, during a sequence of second time intervals distinct from and interspersed with the first time intervals, a second interrogation area that is substantially confined to the second side of the portal; wherein said antenna means receives the marker signal during one of said first time intervals only if the marker is present in said first interrogation area during said one of said first time intervals, and said antenna means receives the marker signal during one of said second time intervals only if the marker is present in said second interrogation area during said one of said second time intervals. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. In an apparatus for detecting a marker which transmits a marker signal, the apparatus being installed at a portal having a first side and a second side, the second side being accessible by travel through the portal from the first side to the second side, a method of detecting a direction in which the marker is moved through the portal, the method comprising the steps of:
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alternately and repetitively transmitting first and second interrogation signals for causing the marker to transmit the marker signal, said first interrogation signal being substantially confined to the first side of the portal, said second interrogation signal being substantially confined to the second side of the portal; and detecting at which one of the first side of the portal and the second side of the portal the marker is present first. - View Dependent Claims (32)
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Specification