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Old January 24th 09, 04:29 AM posted to rec.radio.amateur.antenna
Richard Harrison Richard Harrison is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 588
Default improve S/N for AM car radio by a factor of 2...5...10?

Richard Clark, KB7QHC wrote:
"Which field is chosen won`t mstter much----."

Agreed as the fields trade the same energy back and forth on each cycle.

Narrowing bandwidth is not the only way to reduce noise. Auto radios use
non-directional antennas out of convenience. A desired signal can come
from any direction. But, directivity can improve signal to noise ratio
as it reduces noise from unwanted directions. An example is my
Telefunken receiver which features a large horizontal ferrite rod
antenna. This rod is rotatable in azimuth from a control on the front
panel for best reception. This radio was designed for reception in a
fixed location so azimuth change is needed only when changing stations.
A ferrite rod antenna can be used anywhere to improve s/n ratio through
its high directivity. It requires more inconvenience to reset when the
direction of the vehicle changes and it needs to be mounted outside the
shielded enclosure and equipped with a direction control, i.e. a
rotator.

MFJ among others sells such a ferrite rod antenna for the standard
broadcast band. Aimed for best reception of KGO in San Francisco, it
would discriminate against noise from most other directions.

Best regards, Richard Harrison, KB5WZI