Near field location system and method

• US 20060132352A1
• Filed: 11/10/2005
• Published: 06/22/2006
• Est. Priority Date: 12/21/2004
• Status: Active Grant

• Current Assignee: Q-Track Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Schantz, Hans Gregory, DePierre, Robert Edward, Siwiak, Kazimierz, Gabig, Jerome Sylvester, Wolenec, Glenn
• Granted Patent: US 7,307,595 B2
• Time in Patent Office: Days
• US Class Current: 342/125
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/276 for mounting on helmets
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H04B 5/0075 using inductive coupling transformers or inductances adapted for inductive coupling H01F38/14
• CPC Class Codes: H04B 5/24 Inductive coupling

Abstract

Near field signal properties are used to determine a location by utilizing two magnetic antennas arranged so that the null axes are perpendicular and lie in a plane of interest, such as the horizontal plane. The two antennas may be used as transmitting antennas or receiving antennas. The antennas may be driven so as to produce an equivalent of an omnidirectional pattern in the plane of interest by driving the antennas in an orthogonal manner. The orthogonal drive may be time orthogonal or phase orthogonal. A location is determined based on near field response which may include propagation properties, which may include amplitude, phase, relative amplitude, or phase, or other properties. In one embodiment, multiple transmitters are utilized to determine the location of a single receiver. In another embodiment, multiple receivers are utilized to determine the location of a single transmitter. A space efficient magnetic antenna is disclosed.

Claims

1. A near field method for determining a location, comprising:

providing a first magnetic antenna, said magnetic antenna having a null axis aligned within a predetermined plane;

providing a second magnetic antenna, said second magnetic antenna having a null axis aligned substantially orthogonal to the null axis of said first magnetic antenna and said axis further aligned within said predetermined plane;

transmitting a signal from a transmitter;

receiving said signal by a receiver,

wherein said signal utilizes said first magnetic antenna and said second magnetic antenna; and

determining said location based on a near field signal property of said signal.

2. The method of claim 1, wherein said first magnetic antenna and said second magnetic antenna are used for said transmitting.

3. The method of claim 1, wherein said first magnetic antenna and said second magnetic antenna are used for said receiving.

4. The method of claim 1, wherein said location is the location of said transmitter.

5. The method of claim 1, wherein said location is the location of said receiver.

6. The method of claim 1, wherein the signal characteristic is signal amplitude.

7. The method of claim 1, wherein the location determined is within one wavelength of said signal from said transmitter.

8. The method of claim 1, wherein said first magnetic antenna further comprises a plurality of interconnected magnetic antenna elements, each said magnetic antenna element having a null axis substantially parallel to said null axis of said first magnetic antenna.

9. The method of claim 1, further including an RF module having at least one characteristic physical dimension, wherein said first magnetic antenna has an electrical null axis at a substantial diagonal angle from said at least one characteristic physical dimension.

10. The method of claim 9, wherein the at least one characteristic physical dimension is one of the group consisting of overall length, overall width, and overall height.

11. The method of claim 1, wherein said first magnetic antenna comprises a coil wound around a loopstick axis, said coil having turns lying parallel to a plane, said plane at a substantial diagonal angle from said loopstick axis.

12. The method of claim 1, further including an animal collar, wherein said determining of said location is the location of the animal collar.

13. The method of claim 1, wherein the first magnetic antenna and second magnetic antenna are embedded in clothing and the null axis of said first magnetic antenna is substantially perpendicular to the null axis of said second magnetic antenna, said null axes lying substantially in an azimuthal plane.

14. The method of claim 2, wherein said first magnetic antenna and said second magnetic antenna are utilized alternately to transmit said signal.

15. The method of claim 14, wherein said first magnetic antenna and said second magnetic antenna are switched alternately for a plurality of switching periods, at a rate faster than the receiver response time for averaging the receiver response over said plurality of switching periods.

16. The method of claim 2, wherein the first magnetic antenna and the second magnetic antenna are driven in phase quadrature.

17. A system for determining a location, comprising:

a first magnetic antenna, said magnetic antenna having a null axis aligned within a predetermined plane;

a second magnetic antenna, said second magnetic antenna having a null axis aligned substantially orthogonal to the null axis of said first magnetic antenna and said axis further aligned within said predetermined plane;

a transmitter, said transmitter transmitting a signal;

a receiver, said receiver receiving said signal;

wherein said signal utilizes said first magnetic antenna and said second magnetic antenna

a processor, said processor determining said location based on a near field signal property of said signal.

18. The system of claim 17, further including an electric field antenna associated with said transmitter, said first magnetic antenna and said second magnetic antenna associated with said receiver;

wherein said signal is transmitted utilizing said electric field antenna and said signal is received utilizing said first magnetic antenna and said second magnetic antenna.

19. The system as in claim 17, wherein said transmitter utilizes said first magnetic antenna and said second magnetic antenna to transmit said signal.

20. The system as in claim 19, wherein said second magnetic antenna is driven in phase quadrature with respect to said first magnetic antenna.

21. The system as in claim 17, further including a communication link between said receiver and said processor, said receiver determining a received characteristic of said signal;

said received characteristic communicated to said processor over said communication link, said received characteristic utilized for determining said location.