Orientable antenna with conservation of polarization axes
First Claim
1. Antenna including at least one reflector and at least one source of electromagnetic radiation, each said at least one source being capable of transmitting and/or receiving radiation in a primary direction which links said at least one source to at least one reflector;
- each said at least one source including at least one radiating element and means for exciting said element, said antenna being adapted to transmit or to receive a beam of electromagnetic radiation of arbitrary cross-section and in a preferred radiation direction determined by a disposition and an orientation of said reflector and said at least one source, said beam having polarization axes conferred on said beam by the excitation applied to said at least one source, said beam being orientable by movement of one of said antenna and component parts of said antenna, and said antenna further including mechanical means for defining a relative disposition of said reflector and said at least one source and for rotating said reflector about an electromagnetic radiation propagation axis while holding said at least one source in a position such that the polarization axes remain fixed during said reflector rotation, whereinsaid mechanical means comprises depointing means for rotating said reflector about first and second orthogonal axes, said depointing means driving a support which supports an axial rotation motor for rotating said reflector about the electromagnetic radiation propagation axis without also rotating said at least one source.
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Abstract
An antenna is orientable, directional and capable of use as a transmit and/or receive antenna. It includes at least one reflector, at least one source of electromagnetic radiation including means for exciting the source with two orthogonal linear polarizations and a mechanical system for positioning and holding the source and the reflector. The orientation of the antenna is made up of depointing and rotation about a preferred direction of propagation of the radiation and the mechanical system enables such rotation while keeping the source fixed, so conserving the orientation of the orthogonal linear polarization. A preferred embodiment of the antenna includes a parabolic main reflector and a hyperbolic auxiliary reflector in a Cassegrain geometry, and the mechanical system enables rotation of both reflectors about the preferred direction of radiation and holds the source fixed to conserve the orthogonal linear polarization axes of the beam. Applications include radar, direct broadcast satellites and telecommunications employing frequency re-use by polarization diversity, especially advantageous in space and airborne applications.
41 Citations
21 Claims
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1. Antenna including at least one reflector and at least one source of electromagnetic radiation, each said at least one source being capable of transmitting and/or receiving radiation in a primary direction which links said at least one source to at least one reflector;
- each said at least one source including at least one radiating element and means for exciting said element, said antenna being adapted to transmit or to receive a beam of electromagnetic radiation of arbitrary cross-section and in a preferred radiation direction determined by a disposition and an orientation of said reflector and said at least one source, said beam having polarization axes conferred on said beam by the excitation applied to said at least one source, said beam being orientable by movement of one of said antenna and component parts of said antenna, and said antenna further including mechanical means for defining a relative disposition of said reflector and said at least one source and for rotating said reflector about an electromagnetic radiation propagation axis while holding said at least one source in a position such that the polarization axes remain fixed during said reflector rotation, wherein
said mechanical means comprises depointing means for rotating said reflector about first and second orthogonal axes, said depointing means driving a support which supports an axial rotation motor for rotating said reflector about the electromagnetic radiation propagation axis without also rotating said at least one source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
- each said at least one source including at least one radiating element and means for exciting said element, said antenna being adapted to transmit or to receive a beam of electromagnetic radiation of arbitrary cross-section and in a preferred radiation direction determined by a disposition and an orientation of said reflector and said at least one source, said beam having polarization axes conferred on said beam by the excitation applied to said at least one source, said beam being orientable by movement of one of said antenna and component parts of said antenna, and said antenna further including mechanical means for defining a relative disposition of said reflector and said at least one source and for rotating said reflector about an electromagnetic radiation propagation axis while holding said at least one source in a position such that the polarization axes remain fixed during said reflector rotation, wherein
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19. Antenna including at least one reflector and at least one source of electromagnetic radiation, each said at least one source being capable of transmitting and/or receiving radiation in a primary direction which links said at least one source to at least one reflector;
- each said at least one source including at least one radiating element and means for exciting said element, said antenna being adapted to transmit or to receive a beam of electromagnetic radiation of arbitrary cross-section and in a preferred radiation direction determined by a disposition and an orientation of said reflector and said at least one source, said beam having polarization axes conferred on said beam by the excitation applied to said at least one source, said beam being orientable by movement of one of said antenna and component parts of said antenna, and said antenna further including mechanical means for defining a relative disposition of said reflector and said at least one source and for rotating said reflector about an electromagnetic radiation propagation axis while holding said at least one source in a position such that the polarization axes remain fixed during said reflector rotation, wherein
said at least one source is supported on a first platform and said reflector is supported on a second, mobile platform, and wherein said at least one source remains fixed relative to said first platform on rotation by said second, mobile platform around said first platform, and further comprising depointing means on said second, mobile platform for rotating said reflector about first and second orthogonal axes. - View Dependent Claims (20, 21)
- each said at least one source including at least one radiating element and means for exciting said element, said antenna being adapted to transmit or to receive a beam of electromagnetic radiation of arbitrary cross-section and in a preferred radiation direction determined by a disposition and an orientation of said reflector and said at least one source, said beam having polarization axes conferred on said beam by the excitation applied to said at least one source, said beam being orientable by movement of one of said antenna and component parts of said antenna, and said antenna further including mechanical means for defining a relative disposition of said reflector and said at least one source and for rotating said reflector about an electromagnetic radiation propagation axis while holding said at least one source in a position such that the polarization axes remain fixed during said reflector rotation, wherein
Specification