Topband: Waller Flag

[Lee K7TJR]

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