SYSTEMS AND METHODS FOR STIRRING ELECTROMAGNETIC FIELDS AND INTERROGATING STATIONARY RFID TAGS
First Claim
1. A method of stirring an electromagnetic field during RFID tag interrogation to move peaks and valleys in field intensities comprising:
- introducing a conductor having a width greater than the wavelength of the electromagnetic field into the interrogating electromagnetic field; and
moving the position of the conductor within the interrogating electromagnetic field
2 Assignments
0 Petitions
Accused Products
Abstract
RFID tags are used for many purpose including tracking. RFID interrogators are used to retrieve information from tags. In many applications, RFID interrogators and RFID tags remain stationary during interrogation. Regions of low energy due to interference from either additional antenna or reflections from RFID tags and objects can impede or prohibit the reading of RFID tags residing in such regions. Stirring of the generated electromagnetic field is a method of moving around the regions of low energy, where tags can not be read, during the interrogation process. Mechanical stirring is accomplished by introducing a conductor into the electromagnetic field and moving it about in the field. Solid state stirring is accomplished by introducing a variable conductor into the field and varying the conductivity of the variable conductor. Mathematical stirring is accomplished by use of a plurality of antenna and controlling the phase difference between the antenna in a configuration known as phased antenna arrays.
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Citations
53 Claims
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1. A method of stirring an electromagnetic field during RFID tag interrogation to move peaks and valleys in field intensities comprising:
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introducing a conductor having a width greater than the wavelength of the electromagnetic field into the interrogating electromagnetic field; and
moving the position of the conductor within the interrogating electromagnetic field - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system of interrogating RFID tags comprising:
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an RFID tag;
an RFID interrogator;
an antenna coupled to the RFD) interrogator configured to interrogate RFID tags at a given frequency;
a conductor with length greater than the wavelength of the given frequency residing within the transmission range of the antenna; and
a movement mechanism coupled to the conductor that moves the conductor. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of stirring an electromagnetic field to move peaks and valleys in field intensities comprising:
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introducing a conductor having a width greater than the wavelength of the electromagnetic field into the electromagnetic field and a conductivity which is variable; and
varying the conductivity of the conductor. - View Dependent Claims (18, 19, 20, 21, 22, 23, 30, 31, 32, 33, 34, 35)
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24. A method for interrogating RFID tags in a static interrogation environment comprising:
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providing an antenna for transmitting and receiving RF signals to and from RFID tags;
generating an electromagnetic field of a predetermined frequency in the interrogation environment; and
varying the electromagnetic field in the interrogation environment. - View Dependent Claims (25, 26, 27, 28, 37, 38, 39, 40)
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29. A system of stirring an electromagnetic field energy comprising:
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a conductor having a width greater than the wavelength of the electromagnetic field into the electromagnetic field and a conductivity which is variable; and
stimulus for varying the conductivity of the conductor.
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36. A method for interrogating RFID tags in a static interrogation environment comprising:
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providing an antenna for transmitting and receiving RF signals to and from RFID tags;
generating an electromagnetic field of a predetermined frequency in the interrogation environment; and
varying the electromagnetic field in the interrogation environment,
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41. A system for interrogating an RFID tag comprising:
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an RFID tag;
an RFID interrogator;
an antenna coupled to the RFID interrogator configured to interrogate RFID tags at a given frequency;
a variable conductor with length greater than the wavelength of the given frequency residing within the transmission range of the antenna; and
a stimulus coupled to the variable conductor that varies the conductivity of the variable conductor. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49)
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50. A method for interrogating RFID tags in a static interrogation environment comprising:
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providing a plurality of antennae for transmitting and receiving RF signals to and from RFID tags;
generating an electromagnetic field of a predetermined frequency in the interrogation environment; and
maintaining and varying the phase difference between the antenna as to move high energy field intensities across the interrogation zone.
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51. A system for interrogating RFID tags in a static interrogation environment comprising:
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an RFID tag;
an RFID interrogator;
a plurality of antenna configured to interrogate RFID tags at a given frequency; and
a phase shifter coupled to the plurality of antenna and the RFID interrogator. - View Dependent Claims (52, 53)
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Specification