Communications: directive radio wave systems and devices (e.g. – Directive – Including polarized signal communication transmitter or...
Reexamination Certificate
2000-02-08
2001-11-20
Issing, Gregory C. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including polarized signal communication transmitter or...
C342S383000
Reexamination Certificate
active
06320537
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a multiple beam antenna array. More particularly, the present invention relates to a beam-forming network having a multiple frequency, dual polarization, cell reuse pattern.
BACKGROUND ART
Multiple beam antennas are antennas that form a plurality of communication beams. Commercial communications satellites typically employ multiple beam antennas that have one or more feed elements. The feed elements may be direct radiating or they may feed a reflector or a lens.
Multiple beam antennas have feed element groups that overlap, whereby a feed element is driven to generate a beam component that is combined with component beams from other feed elements to form a composite beam, or communications beam. A low-level beam forming network within the communications satellite controls the interaction of feed elements.
Conventional beam forming networks that generate multiple beams from a feed array describe planar dividers and combiners connected by individual connections having predetermined propagation delays. The beam forming networks are typically comprised of seven-way power dividers and combiners. The excessive number of divider and combiner structures required in these prior art beam forming networks are large and adversely affect signal routing design efficiency.
An example of a prior art beam forming network power divider
100
is shown in FIG.
1
. An input signal is divided seven ways. Each element
103
receives a main vector
102
and six coupled vectors
104
surrounding the main vector
102
. Each signal vector
102
,
104
is weighted in amplitude and phase before combining in a power combiner
200
shown in FIG.
2
. Inputs
202
from six of the adjacent elements
103
are combined to produce a single output. Typically, the power divider network is on a separate section from the power combiner network.
The prior art beam forming networks require divider and combiner networks, like the ones shown in
FIGS. 1 and 2
, that send and receive signal energy from all adjacent cells in two polarizations. For a hexagonal structure, a center cell surrounded by six cells, the dividing network is 1:7 and is repeated for all cells and all polarizations. Undesirable interference occurs between adjacent cells. The seven-way power divider and combiner networks are unnecessarily complex adding unwanted size and weight to the beam-forming network.
SUMMARY OF THE INVENTION
The present invention describes a beam forming network having a divider/combiner network in a dual polarization communications system that uses fewer and smaller elements, affording more efficient routing in the network design. The beam-forming network of the present invention reduces the complexity and the size of the divider/combiner networks.
The present invention is configured such that hexagonally structured feed elements are arranged in columns and rows. No two adjacent columns in the beam-forming network have the same primary polarization, and no two adjacent rows have the same frequency, thereby eliminating potential interference.
Three-way power division is provided for the primary polarization and four-way power division for the non-primary polarization. Elements in adjacent columns have alternating primary polarizations. Therefore, the primary polarization may be right hand circular (RHC) and the non-primary polarization left hand circular (LHC), while in an adjacent column of elements the primary polarization is LHC and the non-primary polarization is RHC. The combiner network of the present invention has seven way combining in every other column. This configuration eliminates unnecessary signal division and combination, thereby improving the efficiency of the beam-forming network and reducing the size of the divider and combiner networks.
The beam-forming network of the present invention uses the symmetry of a hexagonal structure to reduce the size of dividers from 1:7 to a network of 1:3 and 1:4 dividers. Fewer combiners, and smaller dividers reduce the packaging complexity.
It is an object of the present invention to reduce the size and complexity of a beam-forming network. It is another object of the present invention to reduce the size of the dividing network by recognizing the distribution of polarization and frequency between cells. It is yet another object of the present invention to provide a polarization and frequency reuse configuration for a hexagonal structure such that the dividers for a given polarization feed less than all of the adjacent neighbors.
It is a further object of the present invention to provide a dividing network that requires a three-way divider for the primary polarization in cells in the same column and a four-way divider for the non-primary polarization in neighboring cells in adjacent columns. It is still a further object of the present invention to reduce the number of combiners, and therefore the complexity of the combining network.
Yet a further object of the present invention is to provide seven-way combining in alternating columns of feeds in a beam forming network, such that the combiners for a given primary polarization feed less than all of the neighboring feed elements.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 6078287 (2000-06-01), Thompson et al.
Roman, V.I, “Frequency Reuse and System Deployment in Local Multipoint Distribution Service”, IEEE Personal Communications, Dec. 1999, pp. 20-27.
Chien Chih-Hsien
Londre Dale A.
Sutton Kevin L.
Gudmestad Terje
Hughes Electronics Corporation
Issing Gregory C.
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