Antenna mirror scannor with constant polarization characteristics

• US 5,526,008 A
• Filed: 11/28/1994
• Issued: 06/11/1996
• Est. Priority Date: 06/23/1993
• Status: Expired due to Fees

• Current Assignee: AIL Systems, Inc. (ITT, Inc.)
• Original Assignee: AIL Systems, Inc. (ITT, Inc.)
• Inventors: Kaniscak, Gerald M., Meserole, William E., Heller, Paul
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): WIGMORE, STEVEN
• Application Number:
  US08/345,230
• Time in Patent Office: 561 Days
• Field of Search: 343/761, 343/837, 343/839, 343/840, 343/781 P, 343/705
• US Class Current: 343/761
• CPC Class Codes: H01Q 3/20 wherein the primary active element is fixed and the reflecting device is movable

Abstract

An antenna mirror scanner for generating and directing an antenna scanner beam displaying constant polarization vectors. The antenna mirror scanner includes a non-rotating fixed-aperture antenna for transmitting and receiving an electromagnetic plane wave in a form of an antenna scanner beam and a planar reflector with a reflective planar surface. A rotational axis of the planar reflector is aligned orthogonally to a direction of propagation of the antenna scanner beam propagating towards or away from the reflective surface. A motor rotates the planar reflector to direct the antenna scanner beam incident on the reflective surface either into the non-rotating fixed-aperture antenna when the antenna mirror scanner is operating in a receive mode or from the non-rotating fixed-aperture antenna when the antenna mirror scanner is operating in the transmit mode.

Claims

1. An antenna mirror scanner method for generating an antenna scanner beam displaying constant polarization characteristics from a platform having a direction of movement, the antenna mirror scanner method comprising the steps of:

aligning a reflector having at least one reflective surface with a non-rotating fixed-aperture antenna so that the direction of propagation of a plane wave of electromagnetic energy radiated at least one of towards and away from the antenna is orthogonal to a rotational axis of the reflector, the non-rotating fixed aperture antenna having a symmetrical axis;

substantially aligning the symmetrical axis of the non-rotating fixed aperture antenna in a perpendicular manner with the rotational axis of the reflector;

substantially aligning the rotational axis of the reflector in a parallel manner with the direction of movement of the platform; and

rotating the reflector about the rotational axis so that the plane wave is directed as an antenna scanner beam incident upon the at least one reflective surface at least one of towards and away from the non-rotating fixed aperture antenna;

the combination of the steps of aligning the reflector with the non-rotating fixed aperture antenna, aligning the symmetrical axis of the non-rotating fixed aperture antenna with the rotational axis of the reflector, aligning the rotational axis of the reflector with the direction of movement of the platform and rotating the reflector providing an antenna scanner beam displaying constant polarization characteristics.

2. An antenna mirror scanner for generating and directing an antenna scanner beam displaying constant polarization characteristics, the antenna mirror scanner including a platform having a direction of movement, the antenna mirror scanner comprising:

a non-rotating direct-aperture antenna for at least one of transmitting and receiving electromagnetic energy in the form of an antenna scanner beam, the non-rotating direct-aperture antenna having asymmetrical axis;

a reflector having at least one reflective surface being coupled to the platform, an axis of rotation of the reflector being orthogonally aligned with a direction of propagation of the antenna scanner beam propagating at least one of towards and away from the at least one reflective surface, the axis of the reflector being substantially aligned in a perpendicular manner with the symmetrical axis of the non-rotating direct aperture antenna, the axis of rotation of reflector being substantially aligned in a parallel manner with the direction of the movement of the platform; and

means for rotating the reflector about the axis of rotation to direct the antenna scanner beam incident upon the at least one reflective surface.

3. A method of generating and directing an antenna scanner beam displaying a constant polarization vector orientation from a platform having a direction of movement, the method comprising the steps of:

generating electromagnetic energy;

radiating the electromagnetic energy as a plane wave from a non-rotating fixed-aperture antenna towards a reflective planar surface of a planar reflector, an axis of rotation of the planar reflector being orthogonally aligned with an axis of symmetry of the non-rotating fixed-aperture antenna, the non-rotating fixed aperture antenna having symmetrical axis;

substantially aligning the symmetrical axis of the non-rotating fixed aperture antenna in a perpendicular manner with the rotational axis of the reflector;

substantially aligning the rotational axis of the reflector in a parallel manner with the direction of movement of the platform; and

rotating the planar reflector about the axis of rotation to directively reflect the plane wave towards the reflective planar surface to form the antenna scanner beam;

the combination of the steps of generating electromagnetic energy, radiating the electromagnetic energy toward a reflective planer surface, aligning the symmetrical axis of the non-rotating fixed aperture antenna with the rotational axis of the reflector, aligning the rotational axis of the reflector with the direction of movement of the platform and rotating the planar reflector about the axis of rotation providing and directing an antenna scanner beam displaying a constant polarization vector.

4. An antenna mirror scanner for generating and directing an antenna scanner beam displaying constant polarization characteristics, the antenna mirror scanner including a platform having a direction of movement, the antenna mirror scanner comprising:

a non-rotating direct-aperture antenna for at least one of transmitting and receiving electromagnetic energy in the form of the antenna scanner beam;

a planar reflector having at least on reflective planar surface being coupled to the platform, an axis of rotation of the planar reflector being aligned orthogonally with an axis of symmetry of the non-rotating direct-aperture antenna, the axis of rotation of the planar reflector being substantially aligned in a parallel manner with the direction of movement of the platform; and

means for rotating the planar reflector about the axis of rotation to direct the antenna scanner beam incident upon the at least one reflective planar surface at least one of towards and away from the antenna.

5. An antenna mirror scanner as defined by claim 4, wherein the non-rotating direct-aperture antenna includes a parabolic reflector having an axis of symmetry which is aligned orthogonally with the rotational axis of the planar reflector.

6. An antenna mirror scanner as defined by claim 4, wherein the planar reflector includes two reflective planar surfaces enabling two sweeps of an antenna scanner beam formed with each rotation of the planar reflector about the rotational axis thereof.

7. A remote earth radiometric sensor, the remote earth radiometric sensor including a platform having a direction of movement, the remote earth radiometric sensor comprising:

at least one planar reflector having at least one reflective planar surface, an axis of rotation of the at least one planar reflector being positioned orthogonal to an axis of symmetry of the at least one non-rotating direct-aperture receiving antenna, the axis of rotation of the at least one planar reflector being substantially aligned in a parallel manner with the direction of movement of the platform; and

rotation means for rotating the at least one planar reflector to direct an antenna scanner beam displaying constant polarization characteristics resulting from electromagnetic energy radiated from the earth in the form of a plane wave and incident upon the at least one reflective planar surface to the at least one non-rotating direct aperture receiving antenna.

8. A remote earth radiometric sensor as defined by claim 7, wherein the at least one planar reflector includes two reflective planar surfaces such that each complete revolution of the planar reflector provides two complete earth scans with an antenna scanner beam.

9. A remote earth radiometric sensor as defined by claim 7, wherein the rotation of the planar reflector about its rotational axis directs an antenna scanner beam over a linear portion of the earth crosstrack substantially perpendicular to the direction of movement of the moving platform.

10. A remote earth radiometric sensor as defined by claim 7, wherein the at least one non-rotating direct-aperture receiving antenna includes a parabolic reflector having an axis of symmetry which is aligned orthogonally with the rotational axis of the planar reflector.