Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4321431 | Trunk circuit with single coupling transformer | Patrick R. Beirne, Michael C. J. Cowpland | 1982-03-23 |
| 4182936 | Transformerless trunk circuit | Patrick R. Beirne, Michael C. J. Cowpland | 1980-01-08 |