US4879560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radar test device with rotator inside subject-support fixture
Assignee: Northrop Grumman Corp
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Filing: 1988-07-06
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Granted: 1989-11-07
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Expires: 2008-07-06
Abstract
Abstract Measurement of radar cross section is provided by a rotatable platform which supports a test subject to be measured, the rotatable platform and a rotator thereof being enclosed within a fixture configured as a body shaped as an airfoil. A second rotator rotates the fixture body to face a radar antenna which illuminates the test subject, the orientation of the fixture body being selected to minimize a radar cross section of the fixture body. The configuration of the generally airfoil shape minimizes radar cross section in a preferred direction of the body. A metallic seal in the form of a thin foil overlays an interface between the rotatable platform and a surface of the fixture in the manner of a fairing which reduces spurious reflections from the vicinity of the rotator, the seal being formed of a foil having a thickness substantially less than one-quarter wavelength of radiation of the antenna to inhibit generation of reflections from the seal. This permits measurement of very low radar cross sections of the test subject.
Inventors
- 👤 Mark A. McHenry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:55
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/40
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
177 words
A radar test assembly of low radiation cross section for rotatably supporting a test subject to be illuminated by a radar signal from the antenna of a radar set comprising: a fixture, first rotator means for rotating the fixture, a platform for supporting the test subject, means for mounting said platform on said fixture, second rotator means for rotating the platform relative to the fixture, said fixture including a shield extending outwardly from an edge of the platform to form an envelope enclosing said first rotator and the platform and including an opening therein for receiving a test subject to be attached to the platform, the shield having electrically conducting surfaces inclined relative to a direction of propagation of radiation from the antenna for directing reflections of radiation emanating from the fixture away from the antenna, the fixture extending in curved fashion to form a body enclosing the rotator and the platform; and a radiation seal extending from the edge of the opening in the fixture to interface between a surface of the fixture and the platform.
Claim 2
Dependent Claim
177 words
A radar test assembly of low radiation cross section for rotatably supporting a test subject to be illuminated by a radar signal from the antenna of a radar set comprising: a fixture, first rotator means for rotating the fixture, a platform for supporting the test subject, means for mounting said platform on said fixture, second rotator means for rotating the platform relative to the fixture, said fixture including a shield extending outwardly from an edge of the platform to form an envelope enclosing said first rotator and the platform and including an opening therein for receiving a test subject to be attached to the platform, the shield having electrically conducting surfaces inclined relative to a direction of propagation of radiation from the antenna for directing reflections of radiation emanating from the fixture away from the antenna, the fixture extending in curved fashion to form a body enclosing the rotator and the platform; and a radiation seal extending from the edge of the opening in the fixture to interface between a surface of the fixture and the platform.
Claim 3
Dependent Claim
31 words
A test device according to claim 1 wherein said seal interfaces with said fixture at edges which are inclined relative to a general direction of propagation of radiation from the antenna.
Claim 4
Dependent Claim
29 words
A test device according to claim 1 wherein the body of said fixture is configured with a generally air foil shape minimizing radar cross section in a specific direction.
Claim 5
Dependent Claim
30 words
A test device according to claim wherein said seal interfaces with said fixture at edges which are inclined relative to a general direction of propagation of radiation from the antenna.
Claim 6
Dependent Claim
203 words
A radar test assembly of low radiation cross section for rotatably supporting a test subject to be illuminated by a radar signal from the antenna of a radar set comprising: a fixture, first rotator means for rotating the fixture, a platform for supporting the test subject, means for mounting said platform on said fixture, second rotator means for rotating the platform relative to the fixture, said fixture including a shield extending outwardly from an edge of the platform to form an envelope enclosing said first rotator and the platform and including an opening therein for receiving a test subject to be attached to the platform, the shield having electrically conducting surfaces inclined relative to a direction of propagation of radiation from the antenna for directing reflections of radiation emanating from the fixture away from the antenna, the fixture extending in curved fashion to form a body enclosing the rotator and the platform, and a radiation seal extending from the edge of the opening in the fixture to interface between a surface of the fixture and the platform, the seal having the form of a foil with thickness substantially less than one-quarter wavelength of the radiation to inhibit generation of reflections of the radiation.
Claim 7
Dependent Claim
203 words
A radar test assembly of low radiation cross section for rotatably supporting a test subject to be illuminated by a radar signal from the antenna of a radar set comprising: a fixture, first rotator means for rotating the fixture, a platform for supporting the test subject, means for mounting said platform on said fixture, second rotator means for rotating the platform relative to the fixture, said fixture including a shield extending outwardly from an edge of the platform to form an envelope enclosing said first rotator and the platform and including an opening therein for receiving a test subject to be attached to the platform, the shield having electrically conducting surfaces inclined relative to a direction of propagation of radiation from the antenna for directing reflections of radiation emanating from the fixture away from the antenna, the fixture extending in curved fashion to form a body enclosing the rotator and the platform, and a radiation seal extending from the edge of the opening in the fixture to interface between a surface of the fixture and the platform, the seal having the form of a foil with thickness substantially less than one-quarter wavelength of the radiation to inhibit generation of reflections of the radiation.
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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) | 1992-11-06 | 1993-05-08 | 1993-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-06 | 1997-05-08 | 1997-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-06 | 2001-05-08 | 2001-11-07 | $7700.00 | Window Closed / Lapsed |