TRANSMITTING ANTENNA SYSTEM FOR AUDIO INDUCTION COMMUNICATION SYSTEM
First Claim
1. An antenna system for use with an audio induction communication system having a signal source for delivering an electrical signal which varies in frequency directly with the frequency of the message to be transmitted and for producing an active message field in a three dimensional pickup zone located in front of an exhibit and which zone extends horizontally along said exhibit, a substantial distance perpendicularly away from said said exhibit and vertically between two limits sufficient to include the levels of receivers as normally worn or carried by persons viewing said exhibit, said antenna system comprising a plurality of antennas each consisting of an elongated magnetic core and a winding on said core, said antennas being spaced from one another along the length of said exhibit and behind said zone so that each produces a magnetic field a portion of which extends forwardly therefrom and passes through said zone and which portion at any given instant has only one generally vertical direction, and means connecting said antennas to said signal source with such a polar relationship to one another that within said zone said fields are in generally aiding relation to each other.
1 Assignment
0 Petitions
Accused Products
Abstract
A transmitting antenna system for an audio induction communication system provides an active message field within a three-dimensional pickup zone consisting of a magnetic field which varies in frequency directly in accordance with the frequency of the transmitted message. The system comprises a plurality of antennas, each consisting of an elongated core of magnetic material and a winding on the core, located beyond the pickup zone and arranged and energized so that the magnetic field of each antenna within the pickup zone has only one generally vertical direction and so that such one generally vertical direction at any given instant is the same for all of the fields of all of the antennas of said system. By varying the number, the arrangement, the energization and the construction of the individual antennas the shape and size of the pickup zone may be precisely controlled to allow two or more pickup zones to be placed close to one another without mutual interference.
7 Citations
16 Claims
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1. An antenna system for use with an audio induction communication system having a signal source for delivering an electrical signal which varies in frequency directly with the frequency of the message to be transmitted and for producing an active message field in a three dimensional pickup zone located in front of an exhibit and which zone extends horizontally along said exhibit, a substantial distance perpendicularly away from said said exhibit and vertically between two limits sufficient to include the levels of receivers as normally worn or carried by persons viewing said exhibit, said antenna system comprising a plurality of antennas each consisting of an elongated magnetic core and a winding on said core, said antennas being spaced from one another along the length of said exhibit and behind said zone so that each produces a magnetic field a portion of which extends forwardly therefrom and passes through said zone and which portion at any given instant has only one generally vertical direction, and means connecting said antennas to said signal source with such a polar relationship to one another that within said zone said fields are in generally aiding relation to each other.
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2. An antenna system as defined in claim 1 further characterized by all of said antennas being located at the same vertical level relative to said exhibit.
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3. An antenna system as defined in claim 2 further characterized by all of said antennas being arranged with the axes of their elongated magnetic cores being arranged vertically.
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4. An antenna system as defined in claim 2 further characterized by all of said antennas being arranged with the axes of their elongated magnetic cores extending generally horizontally.
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5. An antenna system as defined in claim 1 further characterized by said antennas comprising two separate groups, the antennas comprising one of said groups being located at one level relative to said exhibit and with the antennas comprising the other of said group being located at a level spaced a substantial distance below said one level.
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6. An antenna system as defined in claim 5 further characterized by all of said antennas having the axes of their elongated magnetic cores arranged vertically and with each of the cores of the antennas of said first group being substantially vertically aligned with a corresponding one of the cores of the antennas of said second group.
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7. An antenna system as defined in claim 6 further characterized by all of said antennas being located in a common vertical plane.
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8. An antenna system as defined in claim 5 further characterized by all of said antennas having the axes of their magnetic cores arranged vertically, the antennas of said first group all having substantially similar cores and the antennas of said second group all having substantially similar cores, the cores of said first group of antennas having a length to cross-sectional area ratio substantially different from the length to cross-sectional area ratio of the antennas of said second group.
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9. An antenna system as defined in claim 1 further characterized by all of said antennas being arranged with the axes of their elongated magnetic cores extending vertically, two of said antennas being located respectively near the two front corners of said exhibit at a given vertical level and with a third one of said antennas being located between said first two antennas at a different level.
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10. An antenna system as defined in claim 9 further characterized by said third antenna being located at a level above the level of said first two antennas.
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11. An antenna system as defined in claim 9 further characterized by said first two antennas having substantially similar cores, and the core of said third antenna having a length to cross-sectional area ratio of said first two antennas.
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12. An antenna system as defined in claim 1 further characterized by said antennas including one antenna having its core arranged generally vertically and another antenna having its core arranged generally horizontally.
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13. An antenna system as defined in claim 12 further characterized by said antenna with a generally horizontal core being located at a level near the lower one of said two vertical limits of said pickup zone.
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14. An antenna system as defined in claim 13 further characterized by said antenna with a generally horizontal core being located at a level near the upper one of said two vertical limits of said pickup zone.
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15. An antenna system as defined in claim 13 further characterized by said antenna with a generally horizontal core being located behind said antenna with a generally vertical core.
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16. An antenna system as defined in claim 15 further characterized by said antenna with a generally horizontal core being located behind said antenna with a generally vertical core.
Specification