Multiple frequency reflector antenna with multiple feeds
First Claim
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1. An antenna structure comprising:
- a parabolic reflector having a focal region;
an ellipsoidal subreflector having real and virtual focal points and a dichroic surface, said subreflector being positioned at the focal region of said parabolic reflector in a Gregorian arrangement;
a phased array antenna feed integral with said subreflector and operating in a mid-frequency band, said phased array antenna feed being capable of illuminating said parabolic reflector and including means for correcting for defocusing aberrations, said dichroic surface being transparent to energy in mid-frequency band;
a linear antenna feed operating in high frequency band, said linear feed capable of illuminating said parabolic reflector, said linear feed being positioned in the illumination path of said phased array feed passing through the real focal point generally along a line connecting the real and virtual focal points, thereby reducing mutual blockage between the illumination from said linear feed and said phased array antenna feed; and
a hybrid mode antenna feed operating in a low frequency band, said hybrid mode antenna feed being capable of illuminating said subreflector and being positioned at a point adjacent the virtual focal point of said subreflector.
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Abstract
A reflector antenna system with multiple feeds each operating in a separate frequency band. The antenna system includes a main parabolic reflector and an ellipsoidal subreflector configured in a Gregorian arrangement. Mutual blockage between the multiple feeds is reduced by their orientation and arrangement. The system includes a transversely positioned feed and an axial feed located in the focal region of the main reflector. The transverse feed may be integral with the subreflector. The system also includes a third feed placed at the virtual focal point of the subreflector.
232 Citations
47 Claims
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1. An antenna structure comprising:
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a parabolic reflector having a focal region;
an ellipsoidal subreflector having real and virtual focal points and a dichroic surface, said subreflector being positioned at the focal region of said parabolic reflector in a Gregorian arrangement;
a phased array antenna feed integral with said subreflector and operating in a mid-frequency band, said phased array antenna feed being capable of illuminating said parabolic reflector and including means for correcting for defocusing aberrations, said dichroic surface being transparent to energy in mid-frequency band;
a linear antenna feed operating in high frequency band, said linear feed capable of illuminating said parabolic reflector, said linear feed being positioned in the illumination path of said phased array feed passing through the real focal point generally along a line connecting the real and virtual focal points, thereby reducing mutual blockage between the illumination from said linear feed and said phased array antenna feed; and
a hybrid mode antenna feed operating in a low frequency band, said hybrid mode antenna feed being capable of illuminating said subreflector and being positioned at a point adjacent the virtual focal point of said subreflector. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An antenna structure comprising:
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a primary reflector having a focal region;
an ellipsoidal subreflector having real and virtual focal points and a dichroic surface, said primary reflector and said subreflector being in a Gregorian arrangement;
a first antenna feed positioned adjacent said dichroic surface and being capable of illuminating said primary reflector;
a second antenna feed capable of illuminating said primary reflector and positioned adjacent the real focal point of said subreflector in the path of the illumination of said first antenna feed, said second antenna feed having a major and minor axis, said major axis being substantially parallel to a line connecting the focal points of said subreflector; and
a third antenna feed capable of illuminating said subreflector and positioned adjacent the virtual focal point of said subreflector. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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- 27. An antenna comprising a main reflector having a focal region, a surface feed and a linear feed in the focal region, said surface feed and said linear feed illuminating said main reflector in different frequency bands, said linear feed being between said main reflector and said surface feed and axially aligned generally along the line between the center of said main reflector and the center of said surface feed to thereby reduce interference between the illuminations from said surface and said linear feed.
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30. An antenna comprising:
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a main reflector having a focal region;
an ellipsoidal subreflector having real and virtual focal points and being positioned in the focal region;
a linear feed capable of illuminating said main reflector from a point adjacent the real focal point of said subreflector, said linear feed being oriented in a direction parallel to a line connecting the focal points of said subreflector; and
a hybrid mode feed operating in a lower frequency band than said linear antenna feed capable of illuminating said subreflector from a point adjacent the virtual focal point of said subreflector. - View Dependent Claims (31, 32)
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33. An antenna comprising:
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a main reflector having a focal region;
an ellipsoidal subreflector having real and virtual focal points and being positioned in the focal region;
a surface feed adjacent the surface of said subreflector and following the curvature of the surface of said subreflector and being capable of illuminating said main reflector; and
a hybrid mode feed operating in a lower frequency band than said surface feed, and being capable of illuminating said subreflector from a point adjacent the virtual focal point of said subreflector. - View Dependent Claims (34)
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35. An antenna including a main reflector and an ellipsoidal sub reflector in a Gregorian arrangement and a main reflector feed for illuminating said main reflector and a subreflector feed for illuminating said subreflector, said main reflector feed being in the illumination path of said subreflector feed, and said reflector and subreflector feeds operating in different frequency bands, said main reflector feed being spaced from but parallel to a line connecting the focal points of said subreflector.
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36. An antenna including a main reflector and an ellipsoidal subreflector in a Gregorian arrangement, a reflector feed for illuminating said main reflector in a first frequency band, and a subreflector feed for illuminating said subreflector in a second frequency band, said reflector feed being integral with said subreflector and said subreflector being dichroic to signals in the first frequency band.
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37. An antenna including a main reflector and a subreflector in a Gregorian arrangement, a linear feed for illuminating said main reflector in a first frequency band from a point in the focal region of said main reflector and generally aligned along a line connecting the focal points of said subreflector, and a subreflector feed located adjacent the virtual focal point of said subreflector for illuminating said subreflector in a second frequency band, said subreflector including an integral surface feed capable of illuminating said main reflector in a third frequency band.
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38. A method of conducting communications between a satellite and an earth based antenna in three frequency bands comprising the steps of:
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(a) providing an antenna with a parabolic reflector having a focal region;
(b) positioning an ellipsoidal subreflector at the focal region of the parabolic reflector in a Gregorian arrangement, the subreflector having real and virtual focal points and a dichroic surface;
(c) providing a phased array antenna feed integral with the subreflector, the phased array antenna feed being capable of illuminating the parabolic reflector;
(d) operating the phased array antenna feed in a mid-frequency band to send and receive signals from a satellite;
(e) providing a linear antenna feed positioned in the illumination path of the phased array feed and passing through the real focal point generally along a line connecting the real and virtual focal points and being capable of illuminating the parabolic reflector;
(f) operating the linear antenna feed in a high frequency band to send and receive signals from the satellite;
(g) providing a hybrid mode antenna feed positioned at a point adjacent the virtual focal point of the subreflector and being capable of illuminating the subreflector; and
(h) operating the hybrid mode feed in a low frequency band to send and receive signals from the satellite.
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39. A method of conducting communications between a satellite and an earth based antenna in three frequency bands comprising the steps of:
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(a) sending signals to and receiving signals from a satellite in a mid-frequency band via a parabolic reflector using a phased array antenna feed integral with an ellipsoidal subreflector in a Gregorian arrangement with the parabolic reflector;
(b) sending signals to and receiving signals from a satellite in a high frequency band via the parabolic reflector using a linear antenna feed positioned in the path of rays emitted and received by the phased array feed, the linear feed being positioned along a line passing through the real and virtual focal points of the ellipsoidal subreflector; and
(c) sending signals to and receiving signals from a satellite in a low frequency band via the subreflector and the parabolic reflecting using a hybrid mode antenna feed positioned adjacent the virtual focal point of the subreflector. - View Dependent Claims (40, 41)
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42. A method for conducting communications between a satellite and a reflector antenna in two frequency bands, the antenna including a parabolic main reflector and an ellipsoidal subreflector in a Gregorian arrangement, comprising the steps of:
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illuminating the main reflector in a first frequency band using a linear feed adjacent the real focal point of the subreflector; and
illuminating the main reflector in a second frequency band using a surface feed adjacent the surface of the subreflector, the linear feed being substantially orthogonal to a line at the center of the subreflector tangent to the surface thereby reducing the mutual blockage between the antenna feeds. - View Dependent Claims (43)
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44. A method of using a reflector antenna including a main reflector and an ellipsoidal subreflector in a Gregorian arrangement for conducting communications with a satellite comprising the steps of:
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transmitting signals to and receiving signals from the main reflector using a phased array antenna feed integral with the subreflector; and
transmitting signals to and receiving signals from the main reflector using a horn shaped antenna feed located adjacent the virtual focal point of the subreflector. - View Dependent Claims (45)
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46. An antenna having a main reflector and two feeds illuminating said main reflector from the focal region thereof at different frequencies.
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47. An antenna having a main reflector and three feeds illuminating said main reflector in different frequency bands where all three of said feeds are located generally on a line passing through the center of the main reflector and focal point thereof.
Specification