Adaptive main beam nulling using array antenna auxiliary patterns
First Claim
1. An adaptive nulling system for use with an array antenna, comprising:
- a primary beam forming network to couple signals to and from an array of radiating elements to produce a primary received signal via a primary beam pattern, said beam forming network including ancillary ports providing signals not used in producing said primary received signal;
an auxiliary beam forming network, responsive to signals from said ancillary ports, to produce auxiliary signals received via a number of auxiliary beams;
a controller, responsive to said auxiliary signals and to an adapted received signal, to provide control signals;
a weighting unit, responsive to said control signals and to said auxiliary signals, to provide weighted auxiliary signals; and
a signal combiner arranged to combine said weighted auxiliary signals with said primary received signal to provide said adapted received signal.
1 Assignment
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Accused Products
Abstract
Without use of separate auxiliary antennas, adaptive nulling automatically reduces jamming or other interference affecting a radar or IFF system. A primary beam forming network utilizes four-port directional coupler devices, each having an ancillary port which would have been resistively terminated in the absence of the invention. Signals from ancillary ports are coupled to an auxiliary beam forming network to form auxiliary beam patterns which are orthogonal to and track steered main beam patterns. Auxiliary signals are received via the auxiliary beam patterns. Least mean square (LMS) control loops operate on a feedback basis to derive weighted auxiliary signals responsive to jamming signals. The weighted auxiliary signals are combined with the primary received signals (which may be sum and difference signals) in reverse polarity, so as to be additively destructive of the jamming signals. Multiple LMS control loops enable nulling of jamming signals simultaneously in sum and difference channels. Multiple control loops may be implemented on a time share or multiplexed basis.
43 Citations
27 Claims
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1. An adaptive nulling system for use with an array antenna, comprising:
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a primary beam forming network to couple signals to and from an array of radiating elements to produce a primary received signal via a primary beam pattern, said beam forming network including ancillary ports providing signals not used in producing said primary received signal; an auxiliary beam forming network, responsive to signals from said ancillary ports, to produce auxiliary signals received via a number of auxiliary beams; a controller, responsive to said auxiliary signals and to an adapted received signal, to provide control signals; a weighting unit, responsive to said control signals and to said auxiliary signals, to provide weighted auxiliary signals; and a signal combiner arranged to combine said weighted auxiliary signals with said primary received signal to provide said adapted received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An adaptive nulling system for use with an array antenna, comprising:
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a primary beam forming network to couple signals to and from an array of radiating elements to produce a primary received signal via a primary beam pattern, said beam forming network including ancillary ports providing signals not used in producing said primary received signal; an auxiliary beam forming network responsive to signals from said ancillary ports to produce a number of auxiliary signals, each received via a different auxiliary beam; a controller, responsive to said auxiliary signals and to an adapted received signal, to provide control signals for use with each said auxiliary signal; a weighting unit, including a weighting device responsive to each said auxiliary signal and to control signals provided for use with such auxiliary signal, to provide said number of weighted auxiliary signals; and a signal combiner arranged to combine said weighted auxiliary signals with said primary received signal to provide said adapted received signal. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An adaptive nulling system, comprising:
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an array of radiating elements; a primary beam forming network coupled to said radiating elements to produce a primary sum signal and a primary difference signal via a primary beam pattern, said beam forming network including ancillary ports providing signals not used in producing said primary signals; an auxiliary beam forming network, responsive to signals from said ancillary ports, to produce auxiliary signals received via a number of auxiliary beams; a controller, responsive to said auxiliary signals and to an adapted sum signal and an adapted difference signal, to provide sum and difference control signals; a first weighting unit, responsive to said sum control signals and said auxiliary signals, to provide weighted auxiliary signals; a first signal combiner arranged to combine said weighted auxiliary signals from said first weighting unit with said primary sum signal to provide said adapted sum signal; a second weighting unit, responsive to said difference control signals and said auxiliary signals, to provide weighted auxiliary signals; and a second signal combiner arranged to combine said weighted auxiliary signals from said second weighting unit with said primary difference signal to provide said adapted difference signal. - View Dependent Claims (17, 18, 19, 20, 21)
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22. In an adaptive nulling system for use with an array antenna, an arrangement to provide auxiliary received signals useful for adaptive nulling processing comprising:
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a primary beam forming network to couple signals to and from an array of radiating elements to produce a primary received signal via a primary beam pattern, said beam forming network including ancillary ports providing signals not used in producing said primary received signal; and an auxiliary beam forming network responsive to signals from ancillary ports of said beam forming network to produce auxiliary signals received via a number of auxiliary beams, said auxiliary signals usable for adaptive nulling processing in said adaptive nulling system. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification