Subj : Re: Antenna
To   : TOM WALKER
From : MIKE ROSS
Date : Wed Jul 06 2005 11:58 pm

"TOM WALKER" bravely wrote to "MIKE ROSS" (06 Jul 05  07:20:00)
 --- on the heady topic of "Re: Antenna"

 MR>Think about it a minute, the unbalanced antenna picks up the energy
 MR>wavefront and now needs to dispose of the emf. Now ask yourself the
 MR>question what is the reference for this source of potential, is it the
 MR>radio or is it the Earth? Experiment with a galena or crystal radio
 MR>and see for yourself:
 MR>-> no ground = barely audible signal, good ground = loud signal

 TW> So my 2 Meter Handheld NOR my Radio Shack scanner with it's stubby
 TW> antenna shouldn't really wrok then. That simply is not the case.

Any receiver with a sensitivity of 0.5 microvolts could probably hear
a local transmission even it it didn't have an antenna. It is merely
substituting antenna gain for receiver gain. In either case there is
some form of ground being supplied to the 2 M handheld and the R/S
scanner. It may not be a good ground but the receiver gain compensates
for that to a point. The huge amount of AGC in these is not a fair
comparison with a simple crystal radio and doesn't shed any light on
the matter at hand.

This brings up another solution for our weather radio lacking in gain
problem: add a preamp so we can forget about the antenna and ground.

 M*i*k*e

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