Automotive radar antenna alignment system

• US 6,335,705 B1
• Filed: 06/01/2000
• Issued: 01/01/2002
• Est. Priority Date: 02/17/1999
• Status: Expired due to Fees

• Current Assignee: Anritsu Corporation
• Original Assignee: Anritsu Corporation
• Inventors: Grace, Martin I., Noujeim, Karam, Abou-Jaoude, Ramzi
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US09/587,540
• Time in Patent Office: 579 Days
• Field of Search: H01/Q.132, 343/703, 343/711, 343/713, 342/174, 342/168, 342/165, 340/903
• US Class Current: 343/703
• CPC Class Codes: G01S 7/4017 of HF systems
• CPC Class Codes: G01S 7/4026 Antenna boresight
• CPC Class Codes: G01S 7/403 in azimuth, i.e. in the horizontal plane
• CPC Class Codes: G01S 7/4034 in elevation, i.e. in the vertical plane
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4065 involving a delay line
• CPC Class Codes: G01S 7/4086 in a calibrating environment, e.g. anechoic chamber
• CPC Class Codes: G01S 7/4095 the external reference signals being modulated, e.g. rotating a dihedral reflector or modulating a transponder for simulation of a Doppler echo
• 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 21/061 Two dimensional planar arrays

Abstract

Two receive antennas integrated with power detectors are used to align the thrust vector of a vehicle to the boresite of an automotive radar antenna mounted upon the vehicle. In the system, a signal is transmitted from the radar antenna to the Radar Test System (RTS) positioned as an amplitude only interferometer for testing the radar. Signals received by the RTS antennas are provided to amplitude detectors for generation of amplitude plots of a difference signal, or alternative signal, for display. The boresite angle of the radar antenna is then adjusted until the amplitude of the difference signal, or alternative signal, reaches a minimum to align the radar antenna boresite with the vehicle thrust vector. Additional pairs of receive antennas and detectors may be used to provide boresite alignment both in azimuth and elevation.

Claims

1. A method of aligning a bore site angle of an automotive radar antenna with respect to a mechanical reference line from a vehicle, the method comprising the steps of:

positioning a first receiving antenna and a second receiving antenna along a first line, said first and second receiving antennas having centerlines approximately perpendicular to said first line, said first and second receiving antennas being separated along said first line, said first line having a midpoint between said first and second receiving antennas;

positioning said first and second receiving antennas with respect to said radar antenna such that a centerline of said radar antenna approximately intersects said midpoint of said first line, wherein said centerline of said radar antenna is approximately perpendicular to said first line and approximately parallel to said mechanical reference line;

transmitting a radar signal from said radar antenna;

measuring a first signal received by said first receiving antenna in response to said radar signal;

measuring a second signal received by said second receiving antenna in response to said radar signal;

generating a third signal indicating a difference between said first and second signals; and

adjusting said radar antenna until said third signal is a minimum.

2. The method of claim 1 further comprising the steps of:

determining a sum of said first and second signals; and

multiplying said sum by said difference to generate said third signal prior to said adjusting step.

3. The method of claim 1, further comprising the steps of:

determining a sum of said first and second signals; and

dividing said sum by said difference to generate said third signal prior to said adjusting step.

4. The method of claim 1, wherein the step of positioning said first and second receiving antennas with respect to said radar antenna comprises the steps of:

providing a first laser beam approximately perpendicular to an axle of the automobile; and

moving an alignment fixture supporting the first and second receiving antennas and determining when the light from the first laser beam is reflected from a first reflective material on the alignment fixture.

5. The method of claim 4, further comprising the steps of:

providing a second laser beam from the automobile aligned approximately parallel with the centerline of the radar antenna; and

removing translation errors by moving the alignment fixture and determining when the light from a second laser beam is reflected from a second reflective material on the alignment fixture.

6. The method of claim 1, wherein the mechanical reference line comprises a thrust vector of the automobile.

7. A test system for aligning a bore site angle of an automotive radar antenna with respect to a mechanical reference line from a vehicle comprising:

an alignment fixture;

a first receiving antenna attached to said alignment fixture;

a second receiving antenna attached to said alignment fixture, wherein the first and second receiving antennas are approximately equidistant from the centerline of the antenna alignment system;

a first detector having an input coupled to the first receiving antenna, and having an output, the first detector for detecting an amplitude of a first signal from the radar antenna as received by said first receiving antenna;

a second detector having an input coupled to the first receiving antenna, and having an output, the second detector for detecting an amplitude of the first signal from the radar antenna as received by said second receiving antenna;

a subtractor having inputs coupled to outputs of the first and second detectors, and having an output; and

a display coupled to the output of the subtractor enabling monitoring of the output from said subtractor.

8. The test system of claim 7 further comprising:

a summer having inputs coupled to the outputs of the first and second detectors, and having an output; and

a multiplier having inputs coupled to the outputs of the subtractor and said summer, and having an output coupled to the display to enable monitoring of the output from said multiplier.

9. The test system of claim 7 further comprising:

a summer having inputs coupled to the outputs of the first and second detectors, and having an output; and

a divider having inputs coupled to the outputs of the subtractor and the summer, and having an output coupled to the display to enable monitoring of the output of the divider.

10. The test system of claim 7 further comprising:

a first reflective material positioned on the alignment fixture so that a laser beam when aligned approximately perpendicular to the automobile wheel axle when reflected from the first reflective material will position the transponder approximately along the thrust vector of the vehicle; and

a second reflective material positioned on the alignment fixture so that a laser beam aligned approximately parallel to a centerline of the automotive radar antenna when reflected from the second reflective material will remove translation errors between the centerline of the radar antenna and a centerline of an antenna of the transponder.

11. A method of aligning a bore site angle of an automotive radar antenna with respect to a mechanical reference line from a vehicle, the method comprising the steps of:

positioning a first receiving antenna and a second receiving antenna along a first line, said first and second receiving antennas having centerlines approximately perpendicular to said first line, said first and second receiving antennas being separated along said first line, said first line having a first midpoint between said first and second receiving antennas;

positioning a third receiving antenna and a fourth receiving antenna along a second line, said second and third receiving antennas having centerlines approximately perpendicular to said second line, said third and fourth receiving antennas being separated along said second line, said second line having a second midpoint between said third and fourth receiving antennas, said second line intersecting said first line at a nexus of said second and first midpoints;

positioning said first, second, third, and fourth receiving antennas with respect to said radar antenna such that a centerline of said radar antenna approximately intersects said nexus of midpoints, wherein said centerline of said radar antenna is approximately perpendicular to said first and second lines and is approximately parallel to said mechanical reference line;

transmitting a test signal from said radar antenna;

measuring a first signal received by said first receiving antenna in response to said test signal;

measuring a second signal received by said second receiving antenna in response to said test signal;

measuring a third signal received by said third receiving antenna in response to said test signal;

measuring a fourth signal received by said fourth receiving antenna in response to said test signal;

generating a fifth signal indicating a first difference between said first and second signals;

generating a sixth signal indicating a second difference between said third and fourth signals;

adjusting said radar antenna until said fifth signal is a minimum; and

adjusting said radar antenna until said sixth signal is a minimum.

12. The method of claim 11 further comprising the steps of:

determining a first sum of said first and second signals;

determining a second sum of said third and fourth signals;

multiplying said first sum by said first difference to generate said fifth signal prior to said first adjusting step; and

multiplying said second sum by said second difference to generate said sixth signal prior to said second adjusting step.

13. The method of claim 11 further comprising the steps of:

determining a first sum of said first and second signals;

determining a second sum of said third and fourth signals;

dividing said first sum by said first difference to generate said fifth signal prior to said first adjusting step; and

dividing said sum by said difference to generate said sixth signal prior to said second adjusting step.

14. The method of claim 11, wherein the mechanical reference line comprises a thrust vector of the automobile.

15. A test system for aligning a bore site angle of an automotive radar antenna with respect to a mechanical reference line from a vehicle comprising:

an alignment fixture;

a first receiving antenna attached to said alignment fixture;

a second receiving antenna attached to said alignment fixture;

a third receiving antenna attached to said alignment fixture;

a fourth receiving antenna attached to said alignment fixture;

a first detector having an input coupled to the first receiving antenna, and having an output, the first detector for detecting an amplitude of a first signal from the radar antenna as received by said first receiving antenna;

a second detector having an input coupled to the second receiving antenna, and having an output, the second detector for detecting an amplitude of the first signal from the radar antenna as received by said second receiving antenna;

a third detector having an input coupled to the third receiving antenna, and having an output, the third detector for detecting an amplitude of the first signal from the radar antenna as received by said third receiving antenna;

a fourth detector having an input coupled to the fourth receiving antenna, and having an output, the fourth detector for detecting an amplitude of the first signal from the radar antenna as received by said fourth receiving antenna;

a first subtractor having inputs coupled to the outputs from said first and second detectors, and having an output;

a second subtractor having inputs coupled to the outputs from said third and fourth detectors, and having an output; and

a display coupled to the outputs of the first and second subtractors for monitoring outputs from the first and second subtractors.

16. The test system of claim 15 further comprising:

a first summer having inputs coupled to the outputs of the first and second detectors, and having an output;

a first multiplier having inputs coupled to the outputs of the first subtractor and said first summer, and having an output coupled to the display to enable monitoring of the output from said first multiplier;

a second summer having inputs coupled to the outputs of the third and fourth detectors, and having an output; and

a second multiplier having inputs coupled to the outputs of the second subtractor and said second summer, and having an output coupled to the display to enable monitoring of the output from said second multiplier.

17. The test system of claim 15 further comprising:

a first summer having inputs coupled to the outputs of the first and second detectors, and having an output;

a first divider having inputs coupled to the outputs of the first subtractor and said first summer, and having an output coupled to the display to enable monitoring of the output from said first divider;

a second summer having inputs coupled to the outputs of the third and fourth detectors, and having an output; and

a second divider having inputs coupled to the outputs of the second subtractor and said second summer, and having an output coupled to the display to enable monitoring of the output from said second divider.