Portable transmitter
US4004228A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1974 |
| Grant date | Jan 18, 1977 |
| Priority date | — |
| Expiry date | Apr 29, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A portable transmitter intended to be used to broadcast a signal in response to an external actuation can be constructed so as to include a board such as a so-called printed circuit board carrying a metal coil serving as an antenna. This coil surrounds a central region of the board carrying the operative components of the transmitter other than the antenna and carrying as much excess metal as can be conveniently located generally within the antenna. With this structure, the components and any metal located as described serve as capacitance adjacent to the antenna. As a consequence of the structure the effect of any capacitance adjacent to the exterior of the transmitter is minimized so as to improve antenna performance. When the antenna forms a part of an oscillator circuit in the transmitter so as to determine the oscillator frequency this structure minimizes the effect of any capacitance external to the transmitter affecting the oscillator frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.