Patent US2423459A successfully refreshed from Google Patents.
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 10:20
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H04; H04B; H04B11/00; H04J; H04J99/00
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1455825A
Cited
US818534A
Cited
US1682572A
Cited
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 |