Patent US1977974A successfully refreshed from Google Patents.
US1977974A
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Apparatus for the directional transmission or reception of wave energy
Assignee: ELAC Electroacustic GmbH
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Filing: 1931-06-13
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Granted: 1934-10-23
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Expires: 1951-06-13
Abstract
No abstract record available.
Inventors
- 👤 Rudolph Wilhelm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:47
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/72
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1937-10-22 | 1938-04-23 | 1938-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1941-10-22 | 1942-04-23 | 1942-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1945-10-22 | 1946-04-23 | 1946-10-23 | $7700.00 | Window Closed / Lapsed |