Method and system for receiving distortion-free FM signals by vehicular radios
US4394779A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 6, 1981 |
| Grant date | Jul 19, 1983 |
| Priority date | — |
| Expiry date | Feb 6, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/0814
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Reflected signal distortion in vehicular FM receivers is eliminated or largely suppressed by providing a plurality of antenna elements of the vehicle antenna (13, 100) with different directional characteristics, which are selectively connected to the vehicle receiver (10, 30; 104, 106) if a reflection is sensed in the reflection recognition stage (30, 106). In one embodiment (FIG. 1), the antenna (13) is subdivided into an upper and a lower portion (14, 15), about one-third down its length, the lower portion being surrounded by shielding elements (17-20) positioned about 90.degree. offset from each other, and selectively connectable to, or disconnectable from, ground or vehicle chassis in dependence on sensed distortion or reflection recognition pulses, to reduce the effective antenna length and change the directivity. Upon elapse of a predetermined time interval of between 3 to 10 seconds, for example, as determined by a monostable multivibrator (59, 109), either the main antenna is reconnected or the directivity changed. In another embodiment, a main rod antenna (100) can be disconnected and antenna strips (10, 102), positioned close to the window frames of the windshield and hen…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.