Left-hand circular polarized antenna for use with GPS systems

• US 6,211,823 B1
• Filed: 01/20/1999
• Issued: 04/03/2001
• Est. Priority Date: 04/27/1998
• Status: Expired due to Fees

• Current Assignee: Agero Connected Services, Inc. (Liberty Media Corporation)
• Original Assignee: ATX Research Incorporated
• Inventors: Herring, Russell M.
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/234,566
• Time in Patent Office: 804 Days
• Field of Search: 343/700 MS, 343/711, 343/712, 343/713, 343/797
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/3233 particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 21/26 Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre
• CPC Class Codes: H01Q 9/0428 radiating a circular polarised wave

Abstract

An antenna system, comprising a left-hand circular polarized antenna, is disclosed for use in receiving signals from a GPS location satellite which are originally-transmitted as RHCP signals. Reception occurs after the right-hand circular polarized signal is reflected, or bounces off of, a surface one or more times. The number of reflections must be an odd number. The left-hand circular polarized antenna may be mounted underneath a vehicle or a building overhang. The method of the invention comprises the steps of transmitting a right-hand circular polarized signal and receiving the signal using a left-hand circular polarized antenna placed in a location where the right-hand circular polarized signal must be reflected by an odd number of surfaces before reception.

Claims

1. An antenna system, comprising:

a left-hand circular polarized antenna for receiving a non-line of sight satellite GPS location signal; and

a surface, wherein the non-line of sight satellite GPS location signal is reflected from the surface.

2. The antenna system of claim 1, wherein the left-hand circular polarized antenna receives the non-line-of-sight GPS location signal after the signal is reflected from an odd number of surfaces.

3. The antenna system of claim 1, wherein the antenna receives a right-hand circular polarized signal after the right-hand circular polarized signal is transformed into a left-hand circular polarized signal.

4. The antenna system of claim 3, wherein the right-hand circular polarized signal is transformed into a left-hand circular polarized signal by reflection from an odd number of surfaces.

5. The antenna system of claim 1, wherein the antenna is mounted underneath a vehicle.

6. The antenna system of claim 5, wherein the surface is a surface over which the vehicle travels.

7. The antenna system of claim 6, wherein the non-line-of-sight signal is a left-hand circular polarized signal that has been reflected from the surface directly to the antenna one time after transmission from a satellite.

8. The antenna system of claim 6, wherein the non-line-of-sight signal is a left-hand circular polarized signal that has been reflected from the surface directly to the antenna one time after transmission as a right-hand circular polarized signal.

9. The antenna system of claim 1, wherein the left-hand circular polarized antenna comprises a rectangular patch antenna.

10. The antenna system of claim 1, wherein the left-hand circular polarized antenna comprises a pair of phased dipole antennas.

11. A method for obtaining a GPS location signal, said method comprising the steps of:

transmitting a right-hand circular polarized GPS location signal from an orbiting satellite; and

receiving said right-hand circular polarized GPS location signal with a left-hand circular polarized antenna by placing said left-hand circular polarized antenna in a location where said right-hand circular polarized GPS location signal must be reflected by an odd number of surfaces before being received by said left-hand circular polarized antenna.

12. The method of claim 11, wherein the location is underneath a vehicle.

13. The method of claim 12, wherein the odd number of surfaces is a single surface over which the vehicle travels.

14. The method of claim 11, wherein the location is underneath a building overhang.

15. The method of claim 11, wherein the left-hand circular polarized antenna comprises a rectangular patch antenna.

16. The method of claim 11, wherein the left-hand circular polarized antenna comprises a pair of phased dipole antennas.

17. A vehicle equipped for receiving a satellite right-hand circular polarized signal, said vehicle comprising:

a left-hand circular polarized antenna; and

a surface facing away from the satellite right-hand circular polarized signal line-of-sight, said antenna being attached to said surface so as to receive the satellite right-hand circular polarized signal as a left-hand circular polarized signal.

18. The vehicle of claim 17, wherein the right-hand circular polarized signal bounces an odd number of times before reception by the antenna.

19. The vehicle of claim 18, wherein the odd number is one.

20. The vehicle of claim 17, wherein the antenna comprises a rectangular patch antenna.