Antenna system with plural beam sequential offset

• US 5,563,609 A
• Filed: 05/16/1994
• Issued: 10/08/1996
• Est. Priority Date: 05/16/1994
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Wachs, Marvin R.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/243,351
• Time in Patent Office: 876 Days
• Field of Search: 342/352, 342/353, 342/354, 342/372, 342/425, 342/78, 342/79, 343/763, 343/765, 343/766
• US Class Current: 342/372
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00

Abstract

An array antenna system (40) has a plurality of radiators (44) for generating a set of beams (48), wherein axes of the beams are spaced apart from each other allowing the respective beams to illuminate separate areas of the earth or other receiving region. A sequence of positional offsets (52) is applied to the set of beams by either mechanically (108) moving the radiators to redirect the beams, or by introducing a phase or time-delay taper (84) to the phase shifters (80) or delay lines of a beam former (38) for each of the beams. The succession of positional offsets redirects the beams along a path offset from a central location (50) of each beam, and passing between the sites of adjacent beams. This provides for improved uniformity of illumination of the receiving region. In the event that the antenna system includes time division multiplexing (66) of signals applied (68A-C) to the various beams, the multiplexing is synchronized (98) with the progression of directional offsets to the respective beams to enable a burst transmission to be aimed directly at a receiving site (32) on the earth. Typically, the beams are spaced apart by approximately one beam width.

Claims

1. An array antenna system comprising:

a plurality of radiators and a plurality of signal sources, each of said sources operating at a frequency different from the frequencies of the other sources;

a power divider system for dividing the signal power of each of said sources among a respective plurality of signal paths connecting with respective ones of said radiators;

weighting means disposed in the respective pluralities of signal paths for respective ones of said sources, said weighting means introducing relative phase shifts to signals among the plurality of paths from each source for forming a plurality of beams of radiation from said radiators, wherein axes of the beams are spaced apart from each other allowing the respective beams to illuminate separate areas of a receiving region, there being a space of reduced illumination between said separate illuminated areas;

offset means coupled to said weighting means for combining with said phase shifts a phase progression for offsetting a direction of a plurality of said beams to locate the beams within said reduced illumination space, wherein said offset means includes means for establishing a sequence of phase progressions for offsetting each of said plurality of beams in a sequence of offsets about a central position of said beam; and

wherein said offsets are smaller than a spacing between said beams to provide for enhanced uniformity of illumination by said beams.

2. An antenna system according to FIG. 1 wherein said weighting means provides also for an amplitude weighting to signals among the plurality of paths from each sources for forming said plurality of beams of radiation from said radiators.

3. An antenna system according to FIG. 1 wherein the offsets of a plurality of said beams are accomplished concurrently and in parallel directions.

4. An antenna system according to FIG. 3 wherein the offsets of a plurality of said beams are equal.

5. An antenna system according to FIG. 1 wherein a maximum offset in said sequence of offsets is less than a width of one of said beams.

6. An antenna system according to FIG. 1 wherein a maximum offset in said sequence of offsets is less than half the width of one of said beams.

7. An antenna system according to FIG. 1 wherein the beams are spaced apart by approximately one beam width.

8. An antenna system according to FIG. 1 further comprising means for performing a time division multiplexing of data channels for the signals of respective ones of said sources, thereby to provide for a time division multiplexing of signals carried by said plurality of beams;

and

said offsetting is synchronized with said multiplexing to synchronize transmission of data via respective ones of said channels corresponding to said positions of each beam.