[Lowfer] Active whip antennas

[Bill Ashlock]

 "I wonder if anyone has tried that experiment at a more open site, perhaps hauling the antenna up a wooden mast that wasn't a tree."

John and all,

You may remember an experiment quite a few years back where I set up my E-probe and potable SVM in an open field where trees were at least 200 ft away. I raised the probe mounted on a insulated pole in incremental distances and measured the signal output on the SVM from a constant signal source many miles away. Turned out that the signal strength was very close to being proportional to the height of the probe. I was careful to have plenty of coax laying on the ground at all probe heights so that the capacity of the shield to ground did not vary in any significant degree and was considered very large in comparison to the probe's input capacity to gnd.

Bill



> Date: Sun, 19 Dec 2010 18:43:45 -0500
> From: w1tag at charter.net
> To: lowfer at mailman.qth.net
> Subject: Re: [Lowfer] Active whip antennas
> 
> > No the output of the preamp will be higher due to the fact the antenna is
> > higher up in the air and in the clear compared to being at ground  level
> > and surrounded by lossy obstructions like vegetation and trees, plus  being
> > further away from house wiring and AC noise. I have proved this myself by
> > hoisting an active whip up into a high tree branch and observing the  change
> > in the signal to noise ratio.
> 
> I wonder if anyone has tried that experiment at a more open site, 
> perhaps hauling the antenna up a wooden mast that wasn't a tree.
> 
> John A.
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