Patent US4972192A successfully refreshed from Google Patents.
US4972192A
Expired / Lapsed
US
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Constant amplitude doppler producing radar reflector
Assignee: Georgia Tech Research Corp
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Filing: 1989-11-06
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Granted: 1990-11-20
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Expires: 2009-11-06
Abstract
Abstract A constant amplitude Doppler producing radar reflector for simulating a moving target. A plurality of dihedral reflectors having equal radar cross sections are rotated axially at equal rotational speeds. The dihedral reflectors are separated laterally and in the direction towards the illuminating radar by a distance which keeps the radar returns from the two reflectors in phase quadrature. With the radar cross sections of the reflectors being equal, the return signals to a linearly polarized radar maintains constant amplitude as the dihedral reflectors rotate.
Inventors
- 👤 Joesph A. Bruder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:05
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S7/00; G01S7/02; G01S7/40; G01S7/4052; G01S7/4082; G01S7/4095
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
67 words
A constant amplitude Doppler producing radar reflector for simulating a moving target to an illuminating radar comprising a plurality of axially mounted and rotatable reflectors having substantially equal radar cross-section wherein each reflector is positioned with respect to the others of said plurality of reflectors both laterally and in the direction toward said illuminating radar by a distance such that signals reflected therefrom are in phase quadrature.
Claim 2
Dependent Claim
67 words
A constant amplitude Doppler producing radar reflector for simulating a moving target to an illuminating radar comprising a plurality of axially mounted and rotatable reflectors having substantially equal radar cross-section wherein each reflector is positioned with respect to the others of said plurality of reflectors both laterally and in the direction toward said illuminating radar by a distance such that signals reflected therefrom are in phase quadrature.
Claim 3
Dependent Claim
38 words
The radar reflector of claim 1 wherein said plurality of reflectors are separated from each other in the direction towards the illuminating radar by a distance equivalent to one-eighth of the radar frequency wavelength of said illuminating radar.
Claim 4
Dependent Claim
27 words
The radar reflector of claim 1 wherein said plurality of reflectors comprises a pair of substantially identical dihedral reflectors that are mounted and rotated on separate axes.
Claim 5
Dependent Claim
25 words
The radar reflector of claim 1 wherein said plurality of radar reflectors comprises four dihedral reflectors that are mounted and rotated on a common axis.
Claim 6
Dependent Claim
28 words
The radar reflector of claim 1 wherein said plurality of radar reflectors comprises an array of three dihedral reflectors that are mounted and rotated about a common axis.
Claim 7
Dependent Claim
25 words
The radar reflector of claim 1 wherein said plurality of radar reflectors comprises a pair of dihedral reflectors mounted and rotated on a single axis.
Claim 8
Dependent Claim
58 words
The radar reflector of claim 1 wherein said plurality of axially mounted and rotatable reflectors further comprises at least two substantially identical even bounce dihedral reflectors each rotating on its axis at the same rate with the crease in each reflector set at 45 degrees with respect to the crease in the others of said even bounce reflectors.
Claim 9
Independent Claim
103 words
A method for providing a constant amplitude Doppler producing radar reflector including at least two rotatable diherdral reflectors of equal radar cross section to simulate a moving target to an illuminating radar operating at a radio frequency characterized by a wavelength 1, said method comprising the steps of: mounting each of said plurality of dihedral reflectors on a rotatable shaft; positioning each dihedral reflector with respect to the others of said plurality of dihedral reflectors at a location along its shaft such that signals reflected therefrom are in phase quadrature when they are rotated; and rotating said dihedral reflectors at equal rotational speed.
Claim 10
Independent Claim
103 words
A method for providing a constant amplitude Doppler producing radar reflector including at least two rotatable diherdral reflectors of equal radar cross section to simulate a moving target to an illuminating radar operating at a radio frequency characterized by a wavelength 1, said method comprising the steps of: mounting each of said plurality of dihedral reflectors on a rotatable shaft; positioning each dihedral reflector with respect to the others of said plurality of dihedral reflectors at a location along its shaft such that signals reflected therefrom are in phase quadrature when they are rotated; and rotating said dihedral reflectors at equal rotational speed.
Claim 11
Dependent Claim
69 words
The method of claim 8 wherein the step of rotating the dihedral reflectors includes selecting a simulated radial velocity for said constant amplitude Doppler producing radar reflector and rotating said shaft-mounted dihedral reflectors at a rate given by the formula: ##EQU5## where RPM=the rotational speed of the dihedral reflectors in revolutions per minute, V r =the simulated target radial velocity in km/hr, λ=the illuminating radar's RF wavelength in meters.
Claim 12
Dependent Claim
64 words
The method of claim 8 wherein the step of mounting each of said plurality of dihedral reflectors on a rotatable shaft includes setting up said plurality of dihedral reflectors so that the crease of each of said plurality of dihedral reflectors becomes vertical at 45 degrees of rotation prior to when the crease of any other of said plurality of dihedral reflectors becomes vertical.
Claim 13
Dependent Claim
50 words
The method of claim 8 wherein the step of positioning each dihedral reflector with respect to the others of said plurality of dihedral reflectors includes separating each reflector in the direction towards the illuminating radar by a distance equivalent to one-eighth of the radio frequency wavelength of said illuminating radar.
Claim 14
Dependent Claim
126 words
A constant amplitude Doppler producing radar reflector for simulating a moving target to an illuminating radar comprising a plurality of axially mounted and rotatable reflectors each having an axis of rotation aligned in a direction toward said illuminating radar and each having a crease, said plurality of rotatable reflectors including a first reflector and a second reflector, the second reflector being displaced axially in the direction toward said illuminating radar from the first reflector and the crease of the second reflector displaced in rotation with respect to the crease of the first reflector such that the return signal from said constant amplitude radar reflector to said illuminating radar will be of substantially constant amplitude with an apparent radar cross-section which varies by less than ±3 dB.
Claim 15
Dependent Claim
126 words
A constant amplitude Doppler producing radar reflector for simulating a moving target to an illuminating radar comprising a plurality of axially mounted and rotatable reflectors each having an axis of rotation aligned in a direction toward said illuminating radar and each having a crease, said plurality of rotatable reflectors including a first reflector and a second reflector, the second reflector being displaced axially in the direction toward said illuminating radar from the first reflector and the crease of the second reflector displaced in rotation with respect to the crease of the first reflector such that the return signal from said constant amplitude radar reflector to said illuminating radar will be of substantially constant amplitude with an apparent radar cross-section which varies by less than ±3 dB.
Claim 16
Dependent Claim
36 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said second reflector is positioned with respect to said first reflector by a distance such that signals reflected therefrom are in phase quadrature.
Claim 17
Dependent Claim
44 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said second reflector is displaced from said first reflector in the direction towards the illuminating radar by a distance equivalent to one-eight of the radar frequency wavelength of said illuminating radar.
Claim 18
Dependent Claim
27 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said second reflector is displaced from said first reflector in rotation by 45 degrees.
Claim 19
Dependent Claim
36 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said first reflector includes a plurality of reflectors having a combined radar cross-section substantially equal to the radar cross-section of said second reflector.
Claim 20
Dependent Claim
36 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said second reflector includes a plurality of reflectors having a combined radar cross-section substantially equal to the radar cross-section of said first reflector.
Claim 21
Dependent Claim
49 words
A constant amplitude Doppler producing radar reflector as claimed in claim 12, wherein said first reflector includes a plurality of reflectors and said second reflector includes a plurality of reflectors, the radar cross-section of the first reflector being substantially equal to the radar cross section of the second reflector.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-11-19 | 1994-05-21 | 1994-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-19 | 1998-05-21 | 1998-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-19 | 2002-05-21 | 2002-11-20 | $7700.00 | Window Closed / Lapsed |