Antenna tuning circuit for AM radio receiver
US4403347A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 6, 1981 |
| Grant date | Sep 6, 1983 |
| Priority date | — |
| Expiry date | Feb 6, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An improved antenna tuning circuit for a long and a medium wave AM radio receiver is disclosed. The antenna tuning circuit of the present invention comprises a tuning coil wound around a ferrite core, a variable capacitor connected in parallel with the tuning coil, and a field effect transistor. One end of the tuning coil is connected to the gate electrode directly or through an impedance means, while the other end of the tuning coil is grounded. The output signal of the antenna tuning circuit is taken out from a selected one of the source or drain electrode of the field effect transistor, whereby the signal to noise ratio may be remarkably improved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.