TopBand: Remote signal source

[Eric Gustafson Courtesy Account]

>From: km1h@juno.com (km1h @ juno.com)
>Date: Mon, 23 Mar 1998 12:24:26 EST
>
>Eric and others...
>
>It appears that I will have several points of reference for the tests. A 
>few may alternate between RX and TX as a further test of
performance.



>At the QRP level would not a Beverage also make a good TX antenna?

If aimed directly at the antenna under test, it should be OK.



>And does not an inverted V radiate vertically off the ends?
>

Yes.  If it is aligned exactly with the antenna under test, it
will be coupled in the vertical polarization only.  On higher
bands, I would be worried about reflections from obstacles
muddying up the waters.  But at this frequency, this won't be
much of a problem.



>What should be the maximum distance between myself and the remotes before
>accuracy suffers?
>

During daylight you shouldn't have much trouble at any distance
that your test signal propagates to.  But I would try to stay
within 10 miles or so.



>The polarization will make a difference at ground wave but it
>would also be of interest to include horizontal in the test. The
>key is making accurate measurements and later analyze the data.
>

Both the ground and the direct wave will be vertically
polarized.  Within a 10 mile radius, the only horizontal
component will be due to the radials or to the fact that the
radiators aren't fully vertical (and then only perpindicular to
plane of acute angle).



>The one thing I may not be able to do is NOT have the various
>groups of radials in place. They could be all connected together
>and to a ground rod if that would help minimize the reradiation
>effect.

Don't bother trying to "hide" them from the fields with a ground
rod. 



>I was considering having the radial groups just clip on in
>sequence and use 2M as a liasion.  Coordinating together several
>people at one time is not easy and I feel that trying the tests
>over a week by week time frame would lose accuracy.  I would
>prefer to do it all over several hours on one day and then
>crunch the data. If strange anamolies appear then I would
>reconsider retesting.

You will be beter off going over several days than trying to make
the determination with a lot of conductive material already in
place.  In fact, the test isn't really going to produce valid
results if there is a lot of conductive material in the radial
field area when the small numbers of radials case is evaluated.

Unless the weather makes large variations in the earth
conductivity, readings taken over a reasonable amount of time
should hold up OK.  You can make that determination by taking
measurements at the starting condition over a long time frame
including weather variations.  If it changes, you have a problem
to overcome.  If it doesn't, you can proceed with little concern.


73, Eric  N7CL

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