Patent US4897660A successfully refreshed from Google Patents.
US4897660A
Expired / Lapsed
US
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Structure resonant radar detection apparatus and method
Assignee: R & D ASSOCIATES A CORP OF CALIFORNIA
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Filing: 1986-01-14
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Granted: 1990-01-30
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Expires: 2006-01-14
Abstract
Abstract Certain man-made structures located in a complex background, such as railroad ties, telephone poles, and fences are detected by a flying craft, using a low powered structure resonant radar system. The radar system transmits a radar signal which includes wavelengths of the same order of magnitude as twice the spacing of the elements of the man-made structure or grating multiples thereof, and transmits them in a plurality of different directions and frequencies. Reflections of the transmitted radar are received and structural resonance backscatter is detected wherein the backscatter amplitude at the resonant frequency is much higher than that at adjacent frequencies or that of the clutter background, indicating the presence of the search-for type of structure. The bright structural resonance backscatter can then be exploted by the structure resonant radar for guidance, homing, etc.
Inventors
- 👤 Archie Gold
- 👤 Robert L. Kirkwood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 05:41
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/87; G01S7/00; G01S7/02; G01S7/41; G01S7/414
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
89 words
A method for locating a man-made structure located on land which has a multiplicity of substantially uniformly spaced elements, from a flying craft, comprising: transmitting radar signals in a plurality of different directions that are all at a downward incline from the craft toward the ground; receiving reflections of said radar signals and detecting a resonant frequency that is of at least twice the amplitude of the average frequencies of the received signals; and detecting the direction from which the received signals that included the resonant frequency, was received.
Claim 2
Independent Claim
89 words
A method for locating a man-made structure located on land which has a multiplicity of substantially uniformly spaced elements, from a flying craft, comprising: transmitting radar signals in a plurality of different directions that are all at a downward incline from the craft toward the ground; receiving reflections of said radar signals and detecting a resonant frequency that is of at least twice the amplitude of the average frequencies of the received signals; and detecting the direction from which the received signals that included the resonant frequency, was received.
Claim 3
Dependent Claim
13 words
The method described in claim 1 including: directing said craft in said direction.
Claim 4
Independent Claim
127 words
A method for locating a man-made structure containing periodically-spaced elements, comprising: generating a signal of a frequency, whose inverse times the speed of light approximately equals twice the spacing of said elements times a whole number and transmitting said signal in a known direction towards the ground; at a time after transmitting approximately equal to the travel time of reflections from the ground, receiving reflections of said signal; periodically varying the frequency of said signal, and periodically varying said known direction of transmittal, and comparing the amplitudes of the received signal received after each varying of the frequency and after each varying of the direction of transmittal, and detecting any received signal which is of an amplitude at least twice the average amplitude of all received signals.
Claim 5
Independent Claim
127 words
A method for locating a man-made structure containing periodically-spaced elements, comprising: generating a signal of a frequency, whose inverse times the speed of light approximately equals twice the spacing of said elements times a whole number and transmitting said signal in a known direction towards the ground; at a time after transmitting approximately equal to the travel time of reflections from the ground, receiving reflections of said signal; periodically varying the frequency of said signal, and periodically varying said known direction of transmittal, and comparing the amplitudes of the received signal received after each varying of the frequency and after each varying of the direction of transmittal, and detecting any received signal which is of an amplitude at least twice the average amplitude of all received signals.
Claim 6
Dependent Claim
94 words
Apparatus for locating a man-made structure located on land which has a multiplicity of substantially uniformly spaced elements, from a flying craft, comprising: means for transmitting radar signals in a plurality of different directions that are all at a downward incline from the craft toward the ground; means for receiving reflections of said radar signals and detecting a resonant frequency that is of at least twice the amplitude of the average frequencies of the received signals; and means for detecting the direction from which the received signals that included the resonant frequency, was received.
Claim 7
Dependent Claim
94 words
Apparatus for locating a man-made structure located on land which has a multiplicity of substantially uniformly spaced elements, from a flying craft, comprising: means for transmitting radar signals in a plurality of different directions that are all at a downward incline from the craft toward the ground; means for receiving reflections of said radar signals and detecting a resonant frequency that is of at least twice the amplitude of the average frequencies of the received signals; and means for detecting the direction from which the received signals that included the resonant frequency, was received.
Claim 8
Dependent Claim
131 words
Apparatus for locating a man-made structure containing periodically-spaced elements, comprising: means for generating a signal of a frequency, whose inverse times the speed of light approximately equals twice the spacing of said elements times a whole number, and for transmitting said signal in a known direction towards the ground; means for receiving reflections of said signal at a time after transmitting approximately equal to the travel time of reflections from the ground; periodically varying the frequency of said signal, and periodically varying said known direction of transmittal, and comparing the amplitudes of the received signal received after each varying of the frequency and after each varying of the direction of transmittal, and detecting any received signal which is of an amplitude at least twice the average amplitude of all received signals.
Claim 9
Dependent Claim
131 words
Apparatus for locating a man-made structure containing periodically-spaced elements, comprising: means for generating a signal of a frequency, whose inverse times the speed of light approximately equals twice the spacing of said elements times a whole number, and for transmitting said signal in a known direction towards the ground; means for receiving reflections of said signal at a time after transmitting approximately equal to the travel time of reflections from the ground; periodically varying the frequency of said signal, and periodically varying said known direction of transmittal, and comparing the amplitudes of the received signal received after each varying of the frequency and after each varying of the direction of transmittal, and detecting any received signal which is of an amplitude at least twice the average amplitude of all received signals.
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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) | 1993-01-29 | 1993-07-31 | 1994-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-29 | 1997-07-31 | 1998-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-29 | 2001-07-31 | 2002-01-30 | $7700.00 | Window Closed / Lapsed |