US2423459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency selective apparatus
Assignee: AT&T Inc
•
Filing: 1942-09-15
•
Granted: 1947-07-08
•
Expires: 1962-09-15
Abstract
No abstract record available.
Inventors
- 👤 Warren P Mason
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:19
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H04; H04B; H04B11/00; H04J; H04J99/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1455825A
Cited
US818534A
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US1682572A
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GB279878A
Cited
US1895442A
Cited
US2100348A
Cited
US2169304A
Cited
US2278940A
Cited
US2283285A
Cited
US2233062A
Cited
US2240988A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1950-07-07 | 1951-01-06 | 1951-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1954-07-07 | 1955-01-06 | 1955-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1958-07-07 | 1959-01-06 | 1959-07-08 | $7700.00 | Window Closed / Lapsed |