Antenna apparatus for an electronic security system
First Claim
Patent Images
1. An antenna system comprising:
- a receiving loop antenna;
utilization means coupled to said receiving antenna and operative to provide an output indication of the presence of a resonant tag circuit in coupling relationship with said receiving antenna;
a transmitting loop antenna;
means for disposing said receiving and transmitting antennas in coplanar adjacent spaced balanced coupling relationship;
means for energizing said transmitting antenna to provide an electromagnetic field at a predetermined fixed frequency to alter the resonant properties of a tag circuit present in coupling relationship with said transmitting antenna and including;
coupling means operative to supply energizing signals to said transmitting antenna;
switching means operative to isolate said transmitting antenna from said utilization means upon energization of said transmitting antenna thereby to prevent damage to said utilization means during operation of said transmitting antenna, said switching means including;
a switch device disposed at a symmetrical center position with respect to said receiving antenna and coupled to respective ends thereof; and
a plurality of lead wires interconnecting said switch device and said utilization means and disposed in a centered and orthogonal position with respect to the plane of said receiving antenna to minimize stray coupling between said lead wires and said receiving antenna.
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0 Petitions
Accused Products
Abstract
For use in an electronic security system wherein a resonant tag circuit is sensed to denote an alarm condition, an antenna system which senses the presence of a resonant tag circuit and, upon such sensing, can automatically activate a deactivation field for destruction of the resonant properties of the tag circuit at its sensing frequency and provide an output indication that tag deactivation has been achieved. The antenna system includes a high Q resonant loop antenna for providing a deactivation field, and a coplanar sensing loop antenna isolated from the sensing circuitry during operation of the deactivation antenna.
50 Citations
28 Claims
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1. An antenna system comprising:
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a receiving loop antenna; utilization means coupled to said receiving antenna and operative to provide an output indication of the presence of a resonant tag circuit in coupling relationship with said receiving antenna; a transmitting loop antenna; means for disposing said receiving and transmitting antennas in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna to provide an electromagnetic field at a predetermined fixed frequency to alter the resonant properties of a tag circuit present in coupling relationship with said transmitting antenna and including; coupling means operative to supply energizing signals to said transmitting antenna; switching means operative to isolate said transmitting antenna from said utilization means upon energization of said transmitting antenna thereby to prevent damage to said utilization means during operation of said transmitting antenna, said switching means including; a switch device disposed at a symmetrical center position with respect to said receiving antenna and coupled to respective ends thereof; and a plurality of lead wires interconnecting said switch device and said utilization means and disposed in a centered and orthogonal position with respect to the plane of said receiving antenna to minimize stray coupling between said lead wires and said receiving antenna. - View Dependent Claims (2, 3)
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4. Deactivation antenna apparatus for an electronic security system comprising:
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transmitter means for providing an electromagnetic field in a predetermined area at a first frequency; a multi-resonant tag circuit having a first resonant frequency at said first frequency and a second resonant frequency; a receiving antenna; utilization means coupled to said receiving antenna and operative to provide an output indication of the presence of said tag circuit; a transmitting loop antenna for providing an electromagnetic field in a predetermined area at said second frequency; said receiving and transmitting antennas being disposed in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna to alter the resonant properties of said tag circuit at said first frequency, including; transmitting means; coupling means operative to supply energizing signals from said transmitting means to said transmitting antenna; switching means operative to isolate said receiving antenna from said utilization means upon energization of said transmitting antenna, thereby to prevent damage to said utilization means during operation of said transmitting antenna. - View Dependent Claims (5, 6, 7, 8, 9)
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10. An antenna system comprising:
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a receiving loop antenna operative to provide an output indication of the presence of a resonant tag circuit; a transmitting loop antenna; said receiving and transmitting antennas being disposed in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna to alter the resonant properties of said tag circuit in response to a received signal from said receiving antenna including; signal transmission means operative to supply said received signal to said energizing means; transmitting means operative in response to said received signal; coupling means operative to supply energizing signals from said transmitting means to said transmitting antenna in response to said received signal; and switching means operative in response to said received signal to isolate said receiving antenna from said energizing means upon energization of said transmitting antenna, thereby to prevent damage to said energizing means during operation of said transmitting antenna. - View Dependent Claims (11, 12, 13, 14)
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15. Deactivation antenna apparatus for an electronic security system comprising:
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transmitter means for providing an electromagnetic field in a predetermined area at a first frequency; a multi-resonant tag circuit having a first resonant frequency at said first frequency and a second resonant frequency; a receiving antenna operative to provide an output indication of the presence of said tag circuit; a transmitting loop antenna for providing an electromagnetic field in a predetermined area at said second frequency; said receiving and transmitting antennas being disposed in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna to alter the resonant properties of said tag circuit at said first frequency in response to a received signal from said receiving antenna, including; signal transmission means operative to supply said received signal to said energizing means; transmitting means operative in response to said received signal; coupling means operative to supply electrical signals from said transmitting means to said transmitting antenna in response to said received signal; switching means operative in response to said received signal to disconnect said receiving antenna from said energizing means upon energization of said transmitting antenna, thereby to prevent damage to said energizing means during operation of said transmitting antenna. - View Dependent Claims (16, 17, 18)
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19. An antenna system comprising:
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a receiving loop antenna operative to provide to utilization means an output indication of the presence of a resonant tag circuit; a transmitting loop antenna; said receiving and transmitting antennas being disposed in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna in response to manual actuation, including; transmitting means operative in response to said manual actuation; coupling means operative to supply energizing signals from said transmitting means to said transmitting antenna in response to said manual actuation; and switching means operative in response to said manual actuation to isolate said receiving antenna from said utilization means upon energization of said transmitting antenna, thereby to prevent damage to said utilization means during operation of said transmitting antenna. - View Dependent Claims (20, 21, 22, 23, 24)
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25. Deactivation antenna apparatus for an electronic security system comprising:
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transmitter means for providing an electromagnetic field in a predetermined area at a first frequency; a multi-resonant tag circuit having a first resonant frequency at said first frequency and a second resonant frequency; a receiving antenna operative to provide to utilization means an output indication of the presence of said tag circuit; a transmitting loop antenna for providing an electromagnetic field in a predetermined area at said second frequency; said receiving and transmitting antennas being disposed in coplanar adjacent spaced balanced coupling relationship; means for energizing said transmitting antenna to alter the resonant properties of said tag circuit at said first frequency in response to a manual activation, including; transmitting means operative in response to said manual activation; coupling means operative to supply energizing signals from said transmitting means to said transmitting antenna in response to said manual activation; switching means operative in response to said manual activation to isolate said receiving antenna from said utilization means upon energization of said transmitting antenna, thereby to prevent damage to said utilization means during operation of said transmitting antenna. - View Dependent Claims (26, 27, 28)
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Specification