I must be missing something.
The noise in a 50 ohm resistor is -174 dbm per root Hz at ambient temp.
Lets take 100Hz bandwidth for the receiver and the noise becomes -154 dbm or
.0045 uVolts
Lets add a PERFECT amplifier of 40 db. The noise output of the 40 db amp is
then -114 dbm or 0.446 uVolts
S-2 on a receiver with perfect S meter is .4 uVolts so the RX should set at
S-2 normally.
As I understand it the Waller antenna produces about -45 db of gain over
some reference. (45 db Is 177 time voltage)
So in order to simply match the noise level of .446 uVolts with a signal you
need a signal impinging on this antenna that would produce 79 uVolts in an
antenna similar to the reference.
To me a signal of 79 uVolts is something over S-9 on a receiver. Would a
simple dipole or inverted Vee antenna with essentially no gain produce a
whopping signal from the same source. Of course it would pick up noise as
well but I would think it would not be of an equal S-9 level.
Where did I go wrong in these figures. I must be astray somewhere.
Lee K7TJR OR
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