Scanned antenna system

• US 5,579,021 A
• Filed: 03/17/1995
• Issued: 11/26/1996
• Est. Priority Date: 03/17/1995
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Lee, Jar J.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/405,646
• Time in Patent Office: 620 Days
• Field of Search: 343/754, 343/711, 343/761, 343/772, 343/780, 343/781 R, 343/781 P, 343/781 CA, 343/839, 333/21 R
• US Class Current: 343/781.00P
• CPC Class Codes: H01Q 19/13 the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination H01Q19/15 takes precedence
• CPC Class Codes: H01Q 3/20 wherein the primary active element is fixed and the reflecting device is movable

Abstract

Compact, microwave scanned antennas include combinations of a radiator, a reflector and a mirror. The radiator is formed by plating a shaped dielectric core. It generates an antenna beam at an output aperture in response to a microwave signal at an input port. The wavefront orientation of the antenna beam is a function of the wavefront orientation of the microwave signal at the input port. Changing the angular relationship between the path of the microwave signal and the input port changes the wavefront orentation of the antenna beam and, therefore, its beam axis. Pivoting the reflector realizes the desired angular change in the microwave signal path. Alternatively, the reflector can be fixed and the mirror pivoted to vary the microwave signal path. Antenna embodiments can be physically realized with a single moving part, the shaped dielectric is easy to form and when configured to operate at a high frequency, e.g., 77 GHz, the antenna is small enough to fit behind an automobile license plate.

Claims

1. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a first signal path as a reflected microwave signal;

a mirror positioned to redirect said reflected microwave signal along a second signal path; and

a radiative member formed with a parallel-plate waveguide which has an input port and further formed with a plurality of parallel-plate stubs which issue transversely from said parallel-plate waveguide to form an output aperture which radiates microwave energy that is received through said input port as an antenna beam wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said radiative member is positioned to intersect said second signal path with said input port;

and wherein at least one of said reflector, said mirror and said radiative member is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

2. The scanned antenna of claim 1, wherein said reflector is a parabolic reflector which is configured to cause said reflected microwave signal to be a collimated microwave signal with a constant phase along any plane that is substantially orthogonal with said first signal path.

3. The scanned antenna of claim 2, wherein said parabolic reflector is a pillbox antenna.

4. The scanned antenna of claim 2, wherein said parabolic reflector is a folded pillbox antenna.

5. The scanned antenna of claim 1, wherein said mirror is formed with a substantially flat reflective surface.

6. The scanned antenna of claim 1, wherein said mirror is adapted to pivot and said reflector and said radiative member are fixed.

7. The scanned antenna of claim 1, wherein said reflector is adapted to pivot and said mirror and said radiative member are fixed.

8. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a first signal path as a reflected microwave signal;

a mirror positioned to redirect said reflected microwave signal along a second signal path; and

a radiative member formed with an input port and an output aperture and configured to radiate microwave energy that is received through said input port as an antenna beam from said output aperture;

wherein;

said radiative member includes a parallel-plate waveguide which is configured to define said input port and a plurality of parallel-plate stubs that are arranged to issue from said parallel-plate waveguide and define said output aperture;

said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

said radiative member is positioned to intersect said second signal path with said input port; and

at least one of said reflector, said mirror and said radiative member is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

9. The scanned antenna of claim 8, further including a dielectric core configured to carry said parallel-plate waveguide and said parallel-plate stubs.

10. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a first signal path as a reflected microwave signal;

a mirror positioned to redirect said reflected microwave signal along a second signal path; and

a continuous transverse stub structure formed with an input port and an output aperture and configured to radiate microwave energy that is received through said input port as an antenna beam from said output aperture wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said continuous transverse stub structure is positioned to intersect said second signal path with said input port;

and wherein at least one of said reflector, said mirror and said continuous transverse stub structure is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

11. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a parallel-plate waveguide haying first and second portions;

a plurality of parallel-plate stubs issuing transversely from said first portion to form an antenna aperture;

said second portion adapted to form a reflector which reflects said microwave signal along a first signal path as a reflected microwave signal; and

a mirror pivotably mounted within said parallel-plate waveguide and positioned between said reflector and said first portion to redirect said reflected microwave signal along a second signal path into said first portion.

12. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a parallel-plate waveguide which has first and second portions;

a plurality of parallel-plate stubs that are arranged to issue from said first portion to form an antenna aperture;

a reflector positioned within said second portion to reflect said microwave signal along a first signal path as a reflected microwave signal; and

a mirror pivotably mounted within said parallel-plate waveguide and positioned to redirect said microwave signal along a second signal path into said first portion.

13. The scanned antenna of claim 12, further including a dielectric core configured to fill said first portion and said parallel-plate stubs.

14. The scanned antenna of claim 12, wherein said parallel-plate waveguide is configured to form a 180°

bend between said first and second portions.

15. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a signal path as a reflected microwave signal; and

a radiative member formed with a parallel-plate waveguide which has an input port and further formed with a plurality of parallel-plate stubs which issue transversely from said parallel-plate waveguide to form an output aperture which radiates microwave energy that is received through said input port as an antenna beam wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said radiative member is positioned to intersect said signal path with said input port;

and wherein at least one of said reflector and said radiative member is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

16. The scanned antenna of claim 15, wherein said reflector is a parabolic reflector which is configured to cause said reflected microwave signal to be a collimated microwave signal with a constant phase along any plane that is substantially orthogonal with said signal path.

17. The scanned antenna of claim 15, wherein said parabolic reflector is a pillbox antenna.

18. The scanned antenna of claim 15, wherein said parabolic reflector is a folded pillbox antenna.

19. The scanned antenna of claim 15, wherein said reflector is adapted to pivot and said radiative member is fixed.

20. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a signal path as a reflected microwave signal; and

a radiative member formed with an input port and an output aperture and configured to radiate microwave energy received through said input port as an antenna beam from said output aperture;

wherein;

said radiative member includes a parallel-plate waveguide which is configured to define said input port and a plurality of parallel-plate stubs that are arranged to issue from said parallel-plate waveguide and define said output aperture;

said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

said radiative member is positioned to intersect said signal path with said input port; and

at least one of said reflector and said radiative member is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

21. The scanned antenna of claim 20, further including a dielectric core configured to carry said parallel-plate waveguide and said parallel-plate stubs.

22. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a reflector configured to reflect said microwave signal along a signal path as a reflected microwave signal; and

a continuous transverse stub structure formed with an input port and an output aperture and configured to radiate microwave energy received through said input port as an antenna beam from said output aperture wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said continuous transverse stub structure is positioned to intersect said signal path with said input port;

and wherein at least one of said reflector and said continuous transverse stub structure is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

23. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a parallel-plate waveguide having first and second portions;

a plurality of parallel-plate stubs issuing transversely from said first portion to form an antenna aperture; and

a pivotable reflector which is positioned to reflect said microwave signal into said first portion;

wherein said second portion is extended over said reflector.

24. A scanned antenna for converting a microwave signal into a scanned antenna beam, comprising:

a parallel-plate waveguide which has first and second portions;

a plurality of parallel-plate stubs that are arranged to issue from said first portion to form an antenna aperture; and

a reflector pivotably positioned within said second portion to reflect said microwave signal into said first portion.

25. The scanned antenna of claim 24, further including a dielectric core configured to fill said first portion and said parallel-plate stubs.

26. The scanned antenna of claim 24, wherein said parallel-plate waveguide is configured to form a 180°

bend between said first and second portions.

27. A collision-avoidance system for generating a scanned antenna beam from a microwave signal, comprising:

a motor vehicle; and

a scanned antenna carried on said vehicle wherein said antenna includes;

a) a reflector configured to reflect said microwave signal along a first signal path as a reflected microwave signal;

b) a mirror positioned to redirect said reflected microwave signal along a second signal path; and

c) a radiative member formed with a parallel-plate waveguide which has an input port and further formed with a plurality of parallel plate stubs which issue transversely from said parallel-plate waveguide to form an output aperture which radiates microwave energy that is received through said input port as an antenna beam wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said radiative member is positioned to intersect said second signal path with said input port;

and wherein at least one of said reflector and said mirror is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.

28. A collision-avoidance system for generating a scanned antenna beam from a microwave signal, comprising:

a motor vehicle; and

a scanned antenna carried on said vehicle wherein said antenna includes;

a) a reflector configured to reflect said microwave signal along a signal path as a reflected microwave signal; and

b) a radiative member formed with a parallel-plate waveguide which has an input port and further formed with a plurality of parallel-plate stubs which issue transversely from said parallel-plate waveguide to form an output aperture which radiates microwave energy that is received through said input port as an antenna beam wherein said antenna beam has a phase distribution across said output aperture that is a function of the phase distribution of said microwave energy across said input port;

wherein said radiative member is positioned to intersect said signal path with said input port;

and wherein at least one of said reflector and said radiative member is adapted to pivot and thereby cause the angular relationship between said second signal path and said input port to vary over a predetermined angular range.