Do receiver antennas need matching or not?
Dave wrote:
"Tom Biasi" wrote in message
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"billcalley" wrote in message
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Hi All,
I always hear that antennas have to be matched to their radio, but
in receivers (such as FM and shortwave radios) I see mostly long
random length antennas used, and these antennas -- be they a
telescoping whip or a long wire out a window -- are used over some
really wide bandwidths. How is this possible if an impedance match
must always be maintained for radios? And since there cannot be a
good match over such wide bandwidths with any (typical) wire antenna,
what is the downside to using these completely unmatched long antennas
for receivers? (Poor gain patterns with lots of nulls? Lower
sensitivity due to bad noise figure or gain match for any LNA or
frontend amp? Degraded overall antenna gain)?
Thanks; I'm very confused on this subject!
-Bill
The best transfer of energy is achieved when the antenna impedance matches
the input circuit impedance of the receiver.
OH NO! now you have done it! i hope cecil doesn't see this or you have just
openend another endless energy sloshing around thread! what does happen if
the antenna isn't matched to the radio? where does the mismatch energy
go???
A good deal of it is re-radiated by the antenna.
Cheers,
Phil Hobbs
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