US4495502A
Expired / Lapsed
US
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Multiple loop sidelobe canceller
Assignee: United States Department of the Air Force
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Filing: 1982-01-27
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Granted: 1985-01-22
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Expires: 2002-01-27
Abstract
Abstract A sidelobe canceller using only a widely spaced auxiliary array can lose performance for multiple jammers located at angles corresponding to the grating lobe structure. The degradation is independent of the number of control loops used. A closely spaced auxiliary array cannot resolve and process closely spaced jammers but is less susceptible to grating lobe occurrences. Its performance can degrade for closely spaced jammers while the widely spaced array has the resolution capability required. A dual array approach comprised of both widely and closely spaced subarrays was simulated and tested. Each subarray automatically compensated for the deficiencies of the other. The computer simulations predicted the precise nature and locations of these geometrical conditions when the system was tested. Auxiliary channel preprocessing can successfully be used with the dual array approach to simultaneously minimize the differential level problem for multiple jammers. Without preprocessing of the auxiliary array, little, if any cancellation may be achieved against weaker jammers.
Inventors
- 👤 Raymond J. Masak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:50
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/2813
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
217 words
A space tapered multiple jammer sidelobe canceller comprising first and second subsystems for use in a system having a main system for receiving desired and interfering electromagnetic wave energy from a given angular region of space, and main system having a main beam forming antenna and a main receiving means coupled to the main antenna; said first subsystem comprising a first array of antenna elements, widely spaced several wavelengths between any two elements, and a first unit comprising a plurality of adaptive loops coupled to said antenna elements of the first array; said second subsystem comprising a second array of antenna elements, closely spaced on the order of one wavelength or less between adjacent elements, and a second unit comprising a plurality of adaptive loops coupled to said antenna elements of the second array; and combining means having inputs from said main receiving means, from said first unit and from said second unit, for summing the signals for generating a system output and adaptive control loop feedback signals supplied on leads to the first and second units, said adaptive control loop feedback signals being used to form in said adaptive loops the generation of cancellation signals in response to correlation between interfering signals appearing in the subsystems and the same interfering signals appearing in said main system.
Claim 2
Dependent Claim
217 words
A space tapered multiple jammer sidelobe canceller comprising first and second subsystems for use in a system having a main system for receiving desired and interfering electromagnetic wave energy from a given angular region of space, and main system having a main beam forming antenna and a main receiving means coupled to the main antenna; said first subsystem comprising a first array of antenna elements, widely spaced several wavelengths between any two elements, and a first unit comprising a plurality of adaptive loops coupled to said antenna elements of the first array; said second subsystem comprising a second array of antenna elements, closely spaced on the order of one wavelength or less between adjacent elements, and a second unit comprising a plurality of adaptive loops coupled to said antenna elements of the second array; and combining means having inputs from said main receiving means, from said first unit and from said second unit, for summing the signals for generating a system output and adaptive control loop feedback signals supplied on leads to the first and second units, said adaptive control loop feedback signals being used to form in said adaptive loops the generation of cancellation signals in response to correlation between interfering signals appearing in the subsystems and the same interfering signals appearing in said main system.
Claim 3
Dependent Claim
37 words
A sidelobe canceller as set forth in claim 1, with simultaneous feedback in which the same output of said summing means is used to supply the same feedback signal to both of the first and second units.
Claim 4
Dependent Claim
47 words
A sidelobe canceller as set forth in claim 2, wherein the first array comprises at least two elements and has a total aperture equal to the main antenna aperture; and the second array comprises at least two elements spaced on the order of one wavelength or less.
Claim 5
Dependent Claim
35 words
A sidelobe canceller as set forth in claim 2, wherein each element of each of said first and second arrays is an omnidirectional element, and each is coupled to an auxiliary receiver in its subsystem.
Claim 6
Dependent Claim
245 words
A space tapered multiple jammer sidelobe canceller comprising first and second subsystems for use in a system having a main system for receiving desired and interfering electromagnetic wave energy from a given angular region of space, said main system having a main beam forming antenna and a main receiving means coupled to the main antenna; said first subsystem comprising a first array of three antenna elements in a triangular formation, equally spaced several wavelengths, and a first unit comprising a plurality of adaptive loops coupled to said antenna elements of the first array; said second subsystem comprising a second array of four antenna elements in a linear formation spaced on the order of one wavelength or less, and a second unit comprising a plurality of adaptive loops coupled to said antenna elements of the second array; wherein each element of each of said first and second arrays is an omnidirectional element, and each is coupled to an auxiliary receiver in its subsystem; and combining means having inputs from said main receiving means, from said first unit and from said second unit, for summing the signals for generating a system output and adaptive control loop feedback signals supplied on leads to the first and second units, said adaptive control loop feedback signals being used to form in said adaptive loops the generation of cancellation signals in response to correlation between interfering signals appearing in the subsystems and the same interfering signals appearing in said main system.
Claim 7
Dependent Claim
245 words
A space tapered multiple jammer sidelobe canceller comprising first and second subsystems for use in a system having a main system for receiving desired and interfering electromagnetic wave energy from a given angular region of space, said main system having a main beam forming antenna and a main receiving means coupled to the main antenna; said first subsystem comprising a first array of three antenna elements in a triangular formation, equally spaced several wavelengths, and a first unit comprising a plurality of adaptive loops coupled to said antenna elements of the first array; said second subsystem comprising a second array of four antenna elements in a linear formation spaced on the order of one wavelength or less, and a second unit comprising a plurality of adaptive loops coupled to said antenna elements of the second array; wherein each element of each of said first and second arrays is an omnidirectional element, and each is coupled to an auxiliary receiver in its subsystem; and combining means having inputs from said main receiving means, from said first unit and from said second unit, for summing the signals for generating a system output and adaptive control loop feedback signals supplied on leads to the first and second units, said adaptive control loop feedback signals being used to form in said adaptive loops the generation of cancellation signals in response to correlation between interfering signals appearing in the subsystems and the same interfering signals appearing in said main system.
Claim 8
Dependent Claim
37 words
A sidelobe canceller as set forth in claim 5, with simultaneous feedback in which the same output of said summing means is used to supply the same feedback signal to both of the first and second units.
Claim 9
Dependent Claim
30 words
A sidelobe canceller as set forth in claim 2, 3, 4, or 6, wherein at least one of said subsystems includes preprocessing means coupled before the unit of adaptive loops.
Claim 10
Dependent Claim
22 words
A sidelobe canceller as set forth in claim 7, wherein said preprocessing means in the first subsystem comprises a multilevel sidelobe canceller.
Claim 11
Dependent Claim
70 words
A sidelobe canceller as set forth in claim 8 wherein the second subsystem also includes preprocessing means comprising a beamformer with a Butler Matrix; and selection means including a control switch for operating the system in any of several modes including space uniform modes using only one of said subsystems with or without the preprocessing means, and space tapered modes using both subsystems, either or both with its preprocessing means.
Claim 12
Dependent Claim
24 words
A sidelobe canceller as set forth in claim 7, wherein said preprocessing means in the second subsystem comprises a beamformer with a Butler Matrix.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-22 | 1988-07-23 | 1989-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-22 | 1992-07-23 | 1993-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-22 | 1996-07-23 | 1997-01-22 | $7700.00 | Window Closed / Lapsed |