Scanning directional antenna with lens and reflector assembly

• US 6,396,448 B1
• Filed: 08/15/2000
• Issued: 05/28/2002
• Est. Priority Date: 08/17/1999
• Status: Expired due to Fees

• Current Assignee: EMS Technologies, Inc. (Honeywell International Inc.)
• Original Assignee: EMS Technologies, Inc. (Honeywell International Inc.)
• Inventors: Wann, John Elliott, Freeman, Robert Alan, Black, Donald Nelson Jr., Marsik, James Charles, Zimmerman, Kurt Alan
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): CHEN, SHIH CHAO
• Application Number:
  US09/638,602
• Time in Patent Office: 651 Days
• Field of Search: 343/753,754,757,762,763,766,772,911 R,911 L
• US Class Current: 343/753
• CPC Class Codes: H01Q 19/062 for focusing
• CPC Class Codes: H01Q 3/14 for varying the relative position of primary active element and a refracting or diffracting device
• CPC Class Codes: H01Q 3/16 for varying relative position of primary active element and a reflecting device
• CPC Class Codes: H01Q 3/20 wherein the primary active element is fixed and the reflecting device is movable

Abstract

An antenna comprising a feed for delivering electromagnetic energy to a rotatable combination of a dielectric lens and a reflective surface. The combination of the dielectric lens and the reflective surface is placed proximate to and in front of an energy feed, such as a horn, to support the scanning of an antenna beam in response to rotation of the lens/reflective surface assembly. The lens typically comprises a dielectric material and the reflective surface can comprise a thin layer of material operable to reflect electromagnetic energy. For example, the lens can comprise a half-cylinder shape of dielectric material and the reflective surface can be applied to the flat portion of the half-cylindrical lens. Alternatively, the antenna can comprise two or more electromagnetic feeds and a cylindrical lens of dielectric material including a centrally-embedded, two-sided reflective surface. A positioning system can be used to rotate the combination of the lens and the reflective material proximate to and in front of the electromagnetic feed(s).

Claims

1. An antenna, comprising:

a lens assembly, having the form of a semi-cylinder, comprising a lens and a reflective surface, the lens comprising a flat side coincident with the axis of the semi-cylinder and a curved semi-cylindrical surface centered upon said axis, the reflective surface positioned adjacent to the flat side of the lens and facing the curved semi-cylindrical surface of the lens;

a line source, located outside of the lens and in proximity to the curved semi-cylindrical surface of the lens, the line source being oriented substantially parallel to the axis of the semi-cylinder and operable to emit electromagnetic energy; and

means for rotating the lens assembly about the axis of the semi-cylinder, thereby allowing the line source to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly.

2. The antenna of claim 1, wherein the lens comprises a constant-K dielectric lens.

3. The antenna of claim 1, wherein the lens comprises a Luneberg lens.

4. The antenna of claim 1, wherein the line source comprises a horn antenna having an output aperture for transmitting a beam of electromagnetic energy, the output aperture positioned proximate to the curved semi-cylindrical surface of the lens, thereby placing the lens within the transmission axis of the beam of electromagnetic energy.

5. The antenna of claim 4 wherein the means for rotating the lens is operable to rotate the lens about the axis of the semi-cylinder over a range of 90 degrees, thereby allowing the line source to scan the beam of electromagnetic energy over a range of approximately 180 degrees.

6. The antenna of claim 1 further comprising:

a second lens assembly, having the form of a semi-cylinder, comprising a lens and a reflective surface, the lens comprising a flat side coincident with the axis of the semi-cylinder and a curved semi-cylindrical surface centered upon said axis, the reflective surface positioned adjacent to the flat side of the lens, the flat side of second lens assembly positioned adjacent to the flat side of the lens assembly to form a cylindrical lens assembly;

a second line source located outside and in proximity to the curved semi-cylindrical surface of the lens of the second lens assembly, the second line source being oriented substantially parallel to the axis of the semi-cylinder of the second lens assembly and operable to emit electromagnetic energy, the cylindrical lens assembly formed by the lens assembly and the second lens assembly and positioned between the line source and the second line source,

wherein the rotating means is operative to rotate the cylindrical lens, thereby enabling the line source to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the cylindrical lens and enabling the second line source to scan a beam by reflecting electromagnetic energy from the reflective surface of the second lens assembly during rotation of the cylindrical lens assembly.

7. The antenna of claim 1, wherein the line source is a first line source, the antenna further comprising a second line source, and a switch for switching the coupling of a feed source between either the first line source or the second line source, wherein the first line source is operative to emit electromagnetic energy when the switch couples the first line source to the feed source and the second line source is operative to emit electromagnetic energy when the switch couples the second line source to the feed source.

8. The antenna of claim 1 further comprising an enclosure of conductive material covering a portion of the line source to reduce spurious electromagnetic radiation during rotation of the lens assembly.

9. The antenna of claim 8, wherein the enclosure further comprises an absorptive material positioned adjacent to at least a portion of the conductive material to absorb the spurious electromagnetic radiation.

10. The antenna of claim 1, wherein the line source comprises a parallel-plate antenna and a sub-feed comprising a lens of dielectric material for focusing electromagnetic energy upon the lens assembly, the sub-feed positioned within the parallel-plate structure of the parallel-plate antenna.

11. An antenna, comprising:

a lens assembly comprising a cylindrical lens and a reflective surface embedded within the cylindrical lens, the reflective surface comprising a reflective material facing the curved surface of the cylindrical lens and positioned along the central axis of the, cylindrical lens;

a first line source, located outside of the cylindrical lens and in proximity to the curved surface of the cylindrical lens, the first line source being oriented substantially parallel to the axis of the cylindrical lens and operable to emit electromagnetic energy;

a second line source, located outside of the cylindrical lens and in proximity to the curved surface of the cylindrical lens, the second line source being oriented substantially parallel to the axis of the cylindrical lens and operable to emit electromagnetic energy, the second line source positioned opposite the first line source;

means for rotating the cylindrical lens about its central axis; and

a switch for switching between the first line source and the second line source, the first line source operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly when the first line source is selected by the switch, the second line source operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly when the second line source is selected by the switch.

12. The antenna of claim 11, wherein the cylindrical lens comprises one of a constant-K dielectric lens and a Luneberg lens.

13. The antenna of claim 11 wherein the means for rotating the lens is operable to rotate the lens about the axis of the semi-cylinder over a range of 180 degrees, thereby allowing the combination of the first line source and the second line source to scan a beam of electromagnetic energy over a range of approximately 360 degrees.

14. An antenna, comprising:

a first lens assembly comprising a cylindrical lens and a reflective surface embedded within the cylindrical lens, the reflective surface comprising a reflective material facing the curved surface of te cylindrical lens and positioned along the central axis of the cylindrical lens;

a second lens assembly comprising a cylindrical lens and a reflective surface embedded within the cylindrical lens, the reflective surface comprising a reflective material facing the curved surface of the cylindrical lens and positioned along the central axis of the cylindrical lens, the cylindrical lens of the second lens assembly having lens characteristics different from the cylindrical lens of the first lens assembly;

a transmit antenna, located outside of the first cylindrical lens assembly and in proximity to the curved surface of the first cylindrical lens assembly, the transmit antenna being oriented substantially parallel to the axis of the first cylindrical lens assembly and operable to emit electromagnetic energy;

a first receive antenna, located outside of the first cylindrical lens assembly and in proximity to the curved surface of the first cylindrical lens assembly, the first receive antenna being oriented substantially parallel to the axis of the first cylindrical lens assembly and operable to receive electromagnetic energy;

a second receive antenna;

means for synchronously rotating the first cylindrical lens about its central axis and the second cylindrical lens about its central axis; and

a switch for switching between the first receive antenna and the second receive antenna, the first receive antenna operative to scan a broad beam by in response to reflected electromagnetic energy from the reflective surface during rotation of the first lens assembly when the first receive antenna is selected by the switch, the second receive antenna operative to scan a narrow beam by in response to reflected electromagnetic energy from the reflective surface during rotation of the second lens assembly when the second receive antenna is selected by the switch.

15. The antenna of claim 14 further comprising an enclosure of conductive material covering at least a portion of the transmit antenna and the first and second receive antennas to reduce spurious electromagnetic radiation during rotation of the first and second lens assemblies.

16. The antenna of claim 15, wherein the transmit antenna comprises a parallel-plate antenna and a sub-feed comprising a lens of dielectric material for focusing electromagnetic energy upon the first lens assembly, the sub-feed positioned within the parallel-plate structure of the parallel-plate antenna.

17. An antenna system, comprising:

a lens assembly comprising a cylindrical lens and a reflective surface embedded within the cylindrical lens, the reflective surface comprising a reflective material facing the curved surface of the cylindrical lens and positioned along the central axis of the cylindrical lens;

a plurality of antennas, located outside of the cylindrical lens and in proximity to the curved surface of the cylindrical lens, each antenna being oriented substantially parallel to the axis of the cylindrical lens and operable to communicate electromagnetic energy;

means for rotating the lens assembly about the central axis of the cylindrical lens; and

a switch for switching between any pair of opposing antennas, a first one of the pair of antennas operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly when the first antenna is selected by the switch, the second one of the pair of antennas operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly when the second antenna is selected by the switch.

18. A process for scanning a field-of-view, comprising the steps of:

rotating a lens assembly about its axis, the lens assembly comprising a cylindrical lens and a reflective surface embedded within the cylindrical lens, the reflective surface comprising a reflective material facing the curved surface of the cylindrical lens and positioned along the central axis of the cylindrical lens;

switching between a first antenna and a second antenna positioned opposite the first antenna, the lens assembly between and proximate to the first and the second antennas, the first antenna operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly in response to selection of the first antenna, the second antenna operative to scan a beam by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly in response to selection of the second antenna.

19. An antenna, comprising:

a lens assembly, having the form of a semi-cylinder, comprising a lens and a reflective surface, the lens comprising a flat side coincident with the axis of the semi-cylinder and a curved semi-cylindrical surface centered upon said axis, the reflective surface positioned adjacent to the flat side of the lens and facing the curved semi-cylindrical surface of the lens;

a horn antenna, located outside of the lens and in proximity to the curved semi-cylindrical surface of the lens, the horn antenna being oriented substantially parallel to the axis of the semi-cylinder and operable to emit electromagnetic energy;

means for rotating the lens assembly about the axis of the semi-cylinder, thereby allowing the horn antenna to scan a beam in the elevation plane by reflecting electromagnetic energy from the reflective surface during rotation of the lens assembly; and

means for rotating the combination of the lens assembly and the horn antenna, thereby allowing the horn antenna to scan a beam in the azimuth plane by reflecting electromagnetic energy from the reflective surface during simultaneous rotation of the lens assembly and the combination of the lens assembly and the horn antenna.

20. The antenna of claim 19, wherein

the means for rotating the lens assembly comprises a rotating motor having a belt drive coupled to the lens assembly; and

the means for rotating the combination of the lens assembly and the horn antenna comprises a positioning system.