Distributed antenna array with centralized data hub for determining presence and location of RF tags

• US 8,070,065 B2
• Filed: 05/06/2008
• Issued: 12/06/2011
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: GOLIATH Solutions LLC (Osa Acquisition, LLC)
• Inventors: Pyne, John W., Overhultz, Gary L., Hardman, Gordon E.
• Primary Examiner(s): WALSH, DANIEL I
• Application Number:
  US12/115,657
• Publication Number:
  US 20080258876A1
• Time in Patent Office: 1,309 Days
• Field of Search: 340/572.7, 340/572.1, 340/10.1, 235/451, 235/435, 235/487, 235/385
• US Class Current: 235/451
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil

Abstract

A distributed antenna array with a centralized data hub for determining the presence and location of RF tags has been disclosed. This antenna array centralizes electronics and distributes the RF to zones in a facility to greatly reduce the expense of recurring components for monitoring RF tags. A single BRT/hub with multiple antennas attached to transmit and receive ports is used to cover an entire facility. Large facilities are covered by a small number of the BRT/hub combinations. The BRT/hub has transmit antennas coupled thereto, preferably by co-axial cable, that transmit signals to a portion or all of the RF tags and all or a portion of them modulate and reflect the RF signal to a particular receiving antenna. The receiving antenna then returns the RF signal with tag data to the BRT/hub, preferably by co-axial cable. Also disclosed is an RF backscatter tag that cleanly switches a resonant aperture antenna on and off, thereby greatly increasing the mark-to-space ratio of the backscatter data. This enables tags to be detected by the BRT at much greater distances.

Claims

1. A distributed antenna array system with a centralized data reader/transmitter for determining presence and location of linearly polarized RF tags comprising:

at least one designated area in a facility;

a plurality of sub-areas in each of the at least one designated area;

a plurality of RF tags dispersed in each sub-area, wherein each of the tags is associated with a particular respective object present in the sub area;

a single backscatter reader/transmitter (BRT) in each of the at least one designated area;

and a distributed antenna array in the facility comprising;

at least one transmitting antenna electronically coupled to the single BRT and positioned to interrogate at least a portion of the plurality of RF tags present in each sub-area with a carrier signal, wherein a single transmitting antenna is operable to interrogate a plurality of sub-areas;

a single RF signal receiving antenna present in each sub-area;

and each of the single RF signal receiving antennas present in each sub-area receiving data from each of the RF tags in the sub area that have been interrogated by the at least one transmitting antenna and transferring the received tag data to the BRT, wherein wherein each RF tag comprises an antenna with two ¼

λ

;

a switch coupled to one of the ¼

λ

antennas element for selectively closing and connecting both antenna elements together to form a ½

λ

antenna that reflects the BRT carrier signal and for opening to create two ¼

λ

antenna elements that absorb at least some of the BRT carrier signal; and

a backscatter frequency generator on the tag and coupled to the switch for selectively opening and closing the switch and generating tag data;

and wherein a master BRT is coupled to and is operable to collect the received tag data from each of a plurality of interconnected BRTs and from its respective designated area, and wherein the collected and received tag data is processed to determine the presence and location of the RF tags in a particular facility.

2. The system of claim 1 wherein:

the selected facility is a product sale facility; and

the particular object associated with a tag is a product display, sign, merchandising or advertising material (“

Display”

).

3. The system of claim 1 wherein the system determines that the Display is present in a sub-area in the facility where a person may see or interact with the Display.

4. The system of claim 1 wherein the system determines that the Display is properly installed in a particular location in the sub-area.

5. The system of claim 4 wherein the system determines that the Display is present in the particular location for an appropriate period of time.

6. The system of claim 1 wherein the RF tag is carried by a person in the facility to enable market testing through the use of data collected concerning the Displays in the particular locations visited by the person and the time spent in each particular location.

7. The system of claim 1 wherein the at least one transmitting antenna is a quadrafiler helix antenna having a shaped beam with low gain on axis and high gain to the sides.

8. The system of claim 1 wherein:

each transmitting antenna is connected to the single backscatter reader/transmitter by a coaxial cable; and

each transmitter antenna contains a high power amplifier to recover coaxial cable signal attenuation and a band-pass filter at the proper frequency to reduce noise and/or harmonics.

9. The system of claim 1 wherein the distributed antenna array comprises:

a plurality of transmitting antennae, each of the transmitting antennae being located in or near the designated area to transmit communication signals to at least a portion of the RF tags located in at least some of the sub-areas.

10. The system of claim 1 further comprising:

a plurality of designated areas in the facility;

the single master BRT for interrogating RF tags in its corresponding sub area and also receiving RF tag data of the RF tags in each designated area from the BRTs of each designated area; and

wherein a plurality of BRTs receive response signals from at least a portion of the interrogated tags and couple the response signals to the single master BRT that transmits the response signals to a server that processes the response signals.

11. The system of claim 1 wherein each RF tag comprises:

an antenna system with a resonant aperture; and

a switch coupled to one or more elements of the antenna system to cleanly connect and disconnect selected portions of one or more elements of the antenna system to greatly increase the mark-to-space ratio of the backscatter data.

12. A method for determining presence and location of RF tags using a distributed antenna array with a centralized data hub comprising the steps of:

selecting at least one designated area in a particular facility;

selecting a plurality of sub-areas in each of the designated areas;

placing a plurality of RF tags in each sub-area, each of the tags being associated with a particular object in the sub-area;

placing a single backscatter reader/transmitter (BRT) in each of the at least one designated areas;

and forming a distributed antenna array comprising the steps of;

positioning at least one transmitting antenna in or near the designated area to interrogate at least a portion of the plurality of RF tags in the sub-areas with communication data, wherein the transmitting antenna is electronically coupled to the single BRT, and wherein a single transmitting antenna is operable to interrogate a plurality of sub-areas;

placing a single RF signal receiving antenna in each sub area;

receiving data from each of the of the RF tags in each sub-area by interrogating by the at least one transmitting antenna;

transferring the received data to the BRT, wherein each RF tag comprises an antenna with two ¼

λ

;

a switch coupled to one of the ¼

λ

antennas element for selectively closing and connecting both antenna elements together to form a ½

λ

antenna that reflects the BRT carrier signal and for opening to create two ¼

λ

antenna elements that absorb at least some of the BRT carrier signal; and

a backscatter frequency generator on the tag and coupled to the switch for selectively opening and closing the switch and generating tag data;

and wherein a master BRT is coupled to and collects the received data from each of a plurality of interconnected BRTs and from its respective designated area, and wherein the collected and received data is processed to determine the presence and location of the RF tags in a particular facility.