Earth station antenna system

• US 5,657,031 A
• Filed: 01/07/1991
• Issued: 08/12/1997
• Est. Priority Date: 01/07/1991
• Status: Expired due to Term

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Kim, Chang S., Gaske, Paul, Gardner, Peter L., Moldovan, Nicholas, Anderson, Fredrick C.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/637,567
• Time in Patent Office: 2,409 Days
• Field of Search: 343/757, 343/878, 343/880, 343/882, 343/894, 343/763, 343/765, 343/766, 343/760, 343/840
• US Class Current: 343/757
• CPC Class Codes: H01Q 1/125 Means for positioning

Abstract

A small aperture satellite ground station communications antenna is disclosed. A rectangular section of a curved parabolic reflector is provided having first and second rectangular dimensions. An azimuth elevation pedestal for positioning the reflector is provided such that the antenna bore sight is aligned with a geostationary satellite. The reflector is supported by the pedestal to permit rotation of the reflector about a third polarization axis for the antenna. The rotation along the polarization axis permits the reflector to be optimally positioned such that its long dimension is aligned with an orbital arc of a geostationary satellite. Angle scales are provided on all three axes to facilitate repositioning to other satellites based on an initial satellite location, which serves as a reference for the scales.

Claims

1. A small aperture satellite communications antenna comprising:

a reflector and antenna feed forming an antenna having a substantially rectangular aperture longer in one dimension than in another dimension, said antenna having a beam width centered about a bore sight axis, said beam width along the longer dimension being narrower than the beam width along said another dimension to distinguish signals from one satellite lying along a common orbital arc from signals of other satellites along said arc;

an azimuth-elevation pedestal for pointing said bore sight axis associated with said antenna at said one geostationary satellite lying along said common orbital arc with a plurality of other geostationary satellites; and

,

a polarization support means for rotatably supporting said antenna on said azimuth elevation pedestal, said polarization support means providing rotational motion of said reflector and antenna feed to align said longer dimension of said reflector and antenna feed into coincidence with said orbital arc of a geostationary satellite, whereby said narrower beam width is aligned with said orbital arc to receive said one satellite signal.

2. A small aperture satellite communication antenna of claim 1 further comprising a polarization indicator for indicating relative angular position of said longer dimension with respect to a reference position.

3. The small aperture satellite communications antenna of claim 1, wherein said reflector and antenna feed comprise:

a reflector having a rectangular aperture; and

,

an offset feed for illuminating said aperture.

4. A small aperture satellite communication antenna comprising:

(a) a rectangular section of a curved reflector having first and second rectangular dimensions;

(b) a feed for illuminating said reflector supported on said curved reflector to form a secondary radio frequency energy beam concentrated by said rectangular section of said curved reflector, said beam having a narrower beamwidth along said first dimension than said second dimension;

(c) an azimuth elevation pedestal for positioning said reflector so that the radiation pattern of said illuminated reflector is aligned with one geostationary satellite lying along a common orbit with a plurality of other geostationary satellites; and

,

(d) a reflector support assembly connected to the rear side of said rectangular section, said assembly including means for rotating said reflector about a bore sight axis of said reflector secondary radio frequency beam to position said first dimension coincident with said geostationary satellite orbit, whereby said narrower beamwidth receives said one satellite signal.

5. The communication antenna of claim 4 wherein said reflector support assembly comprises a backing structure connected to a polarization platform which rotates about a rotational axis perpendicular to an elevation platform of said azimuth elevation pedestal, said backing structure supporting said reflector so that a central axis of said reflector is at an angle to said rotational axis.

6. The small aperture satellite communications antenna of claim 4 comprising an indicator means for identifying the angular position of one of said reflector rectangular dimensions with respect to a reference position.

7. The small aperture communication antenna of claim 4 wherein said feed and curved reflector constitute an offset feed antenna.