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US3500259A
Expired / Lapsed
US
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Filter circuits using alternate openand short-circuited 3 db quadrature hybrids
Assignee: AT&T Inc
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Filing: 1967-09-29
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Granted: 1970-03-10
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Expires: 1987-09-29
Abstract
No abstract record available.
Inventors
- 👤 Harold Seidel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:44
CPC Classifications
H; H01; H01P; H01P5/00; H01P5/12; H01P5/16; H01P1/00; H01P1/20; H01P1/207; H01P1/209
Claims Analysis
Total Claims: 0
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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) | 1973-03-09 | 1973-09-08 | 1974-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-03-09 | 1977-09-08 | 1978-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-03-09 | 1981-09-08 | 1982-03-10 | $7700.00 | Window Closed / Lapsed |