Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
2000-01-19
2001-11-27
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S754000, C343S7810CA, C342S352000
Reexamination Certificate
active
06323817
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to antenna systems, and in particular to an antenna cluster configuration for wide-angle coverage.
2. Description of Related Art
Communications satellites have become commonplace for use in many types of communications services, e.g., data transfer, voice communications, television spot beam coverage, and other data transfer applications. As such, satellites must provide signals to various geographic locations on the Earth's surface. As such, typical satellites use customized antenna designs to provide signal coverage for a particular country or geographic area.
In order to provide signal coverage over a large area, several approaches are used. A single beam with a wide beamwidth is sometimes used, but is limited in terms of power delivery over such a large geographic area. Typically, to cover a large geographic area, contiguous spot beams are used.
Contiguous spot beams are generated by multiple antennas to cover a large geographic area with a small variation in measured signal strength at the ground. However, in order to generate high-performance beams over the northern and southern hemisphere with a single spacecraft, it is necessary to use either a three to four wide-scan antenna configuration, or a six narrow-scan antenna configuration.
A wide scan antenna is typically a Side Feed Offset Cassegrain (SFOC) or a lensed antenna. Currently, spot-beam satellites using Ku and Ka-band communications links require antenna apertures of 100 inches. Accommodating four one hundred inch apertures on a single spacecraft is difficult. For example, the SFOC geometries are suitable on the East and West sides of the spacecraft, but not on the nadir of the spacecraft. The alternative six narrow-scan antenna configuration also required complex mechanical packaging.
It can be seen, then, that there is a need in the art for antenna systems that can deliver contiguous spot beams over large geographic areas. It can also be seen that there is a need in the art for antenna systems that can deliver contiguous spot beam coverage over both the Northern and Southern hemispheres. It can also be seen that there is a need in the art for antenna systems that provide ease of mechanical design and construction to reduce spacecraft costs.
SUMMARY OF THE INVENTION
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and apparatus for producing contiguous spot beam communications coverage on the Earth's surface. The apparatus comprises an antenna system including two wide scan antennas and two narrow scan antennas. The two wide scan antennas are disposed substantially opposite each other, and the two narrow scan antennas are disposed substantially opposite each other and substantially normal to the wide scan antennas. The first wide scan antenna, second wide scan antenna, and first narrow scan antenna produce a first beam pattern on a planetary surface and the first wide scan antenna, second wide scan antenna, and second narrow scan antenna produce a second beam pattern on the planetary surface.
The present invention provides an antenna system that provides contiguous spot beams over large geographic areas. The present invention also provides antenna systems that can deliver contiguous spot beam coverage over both the Northern and Southern hemispheres. The present invention also provides antenna systems that provide ease of mechanical design and construction to reduce spacecraft costs.
REFERENCES:
patent: 5642358 (1997-06-01), Dent
patent: 5652597 (1997-07-01), Caille
patent: 5945946 (1999-08-01), Munger
patent: 6160519 (2000-12-01), Hemmi
patent: 6184828 (2001-02-01), Shoki
Law Philip H.
Ramanujam Parthasarathy
Robinson Stephen A.
Chen Shih-Chao
Gudmestead Terje
Hughes Electronics Corporation
Wong Don
LandOfFree
Antenna cluster configuration for wide-angle coverage does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Antenna cluster configuration for wide-angle coverage, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Antenna cluster configuration for wide-angle coverage will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2575873