US3879731A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedance load for radar target cross section control element
Assignee: United States Department of the Air Force
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Filing: 1971-11-22
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Granted: 1975-04-22
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Expires: 1991-11-22
Abstract
Abstract Radar target cross section control can be achieved by antenna elements that are terminated by impedance loads whose impedance values decrease with increasing incident electromagnetic wave frequency. An impedance load that accomplishes this over a wide frequency band and that utilizes only passive elements is disclosed. It comprises a length of transmission-line terminated in its own characteristic impedance and having a multiplicity of reflector elements disposed along its length. The reflector elements are geometrically spaced and electrically tuned such that maximum reflection (or scattering) of electromagnetic waves occurs at points progressively closer to the load input terminal as electromagnetic wave frequency increases.
Inventors
- 👤 Richard B Mack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:03
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/14; G; G01; G01S; G01S7/00; G01S7/02; G01S7/40
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
84 words
An impedance load for a radar target cross section control element comprising a length of transmission-line terminated in its characteristic impedance, a coupler engaging the unterminated end of the transmission-line to said control elements, and a plurality of reflecting elements disposed in spaced relationship along the transmission-line, each reflecting element being electrically tuned for maximum reflectivity at a different frequency, successive elements being spaced at increasing distances and ordered to provide maximum reflectivity at decreasing frequencies in a direction away from said coupling means.
Claim 2
Dependent Claim
84 words
An impedance load for a radar target cross section control element comprising a length of transmission-line terminated in its characteristic impedance, a coupler engaging the unterminated end of the transmission-line to said control elements, and a plurality of reflecting elements disposed in spaced relationship along the transmission-line, each reflecting element being electrically tuned for maximum reflectivity at a different frequency, successive elements being spaced at increasing distances and ordered to provide maximum reflectivity at decreasing frequencies in a direction away from said coupling means.
Claim 3
Dependent Claim
84 words
An impedance load for a radar target cross section control element comprising a length of transmission-line terminated in its characteristic impedance, a coupler engaging the unterminated end of the transmission-line to said control elements, and a plurality of reflecting elements disposed in spaced relationship along the transmission-line, each reflecting element being electrically tuned for maximum reflectivity at a different frequency, successive elements being spaced at increasing distances and ordered to provide maximum reflectivity at decreasing frequencies in a direction away from said coupling means.
Claim 4
Dependent Claim
84 words
An impedance load for a radar target cross section control element comprising a length of transmission-line terminated in its characteristic impedance, a coupler engaging the unterminated end of the transmission-line to said control elements, and a plurality of reflecting elements disposed in spaced relationship along the transmission-line, each reflecting element being electrically tuned for maximum reflectivity at a different frequency, successive elements being spaced at increasing distances and ordered to provide maximum reflectivity at decreasing frequencies in a direction away from said coupling means.
Claim 5
Dependent Claim
17 words
An impedance load as defined in claim 1 wherein said transmission-line comprises a length of coaxial cable.
Claim 6
Dependent Claim
17 words
An impedance load as defined in claim 2 wherein said reflecting elements include variable capacitance tuning means.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |