ASA Electronics MS-407 - Manual (Page 11)

Special circuitry in electronic tuned radios
or AM trimmers in mechanically tuned radios,
make up for some of this difference in optimum
mast length for AM reception.
ANTENNA CABLE
Increasing the antenna lead cable (adding
extensions) will reduce sensitivity of AM with
electronic tuned radios.
GROUND PLANES
Ground planes are also important when
considering antenna performance. Most
automotive antennas are designed to be
mounted on the metal body of the vehicle.
The metal body reflects the signal
interference generated by the vehicle’s electrical
system while it also provides the ground for the
antenna lead shield. All this is necessary in order
to maintain a good signal, especially AM.
FM RECEPTION
FM reception can be received with a very
limited antenna and strong local FM stations can
be received without an antenna, depending on the
circumstances.
CONCLUSION
AM/FM reception is subject to the choice of
an antenna and it’s application. There can also be
a variety of methods used to supply signal to both
primary and secondary radios, but AM
performance is the ultimate “test”.
It appears that consumers or end users are
becoming much more critical when it comes to
acceptable antenna performance. It may be
necessary for manufacturers to re-evaluate what
was once considered acceptable.
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