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Old January 30th 05, 02:41 AM
Roy Lewallen
 
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Let me encourage you to build a vertical antenna and arrage a switch so
you can switch back and forth between it and your dipole. Be sure to use
a current balun or two in your dipole feedline so it doesn't become part
of the test.

Here's what I think you'll find, as I have when comparing a vertical to
a horizontal antenna. At times, one antenna will be spectacularly better
than the other -- by 20 dB or more. After a while, maybe a minute or so,
the signal on the good antenna will fade, and when you switch you'll
find that the other antenna is now a lot better than the formerly good
one, by about the same amount. This cycle can go on for quite a while.
This is likely due to polarization rotation (although multipath can
cause a similar effect, if the antennas are spaced far enough apart);
whichever antenna has the right polarization for the moment will be much
better than the other.

I don't believe you'll find any spectacular overall improvement by using
the vertical.

When doing these tests, don't make the mistake of assuming the units on
your S-meter are some particular number of dB, unless you have the
abililty to actually measure them. Any assumption you make could be WAY off.

Roy Lewallen, W7EL

Buck wrote:
I occasionally chase counties when I am sitting at my desk doing other
things and have the radio available. Right now I am using a
horizontal dipole antenna to make contacts. The downside of this is
that many times I can't hear the mobiles or they can't hear me.

I am thinking that I might be able to improve my contacts by using a
vertical antenna since most mobiles use vertical antennas. I have
heard that once the signal bounces off the ionosphere, polarity isn't
as important as it is for local communications. However, when I was
assembling a 2 meter dipole antenna, I held it horizontal and turned
it vertical. I saw the s-meter go from nothing to s-7 and the
repeater go from silent to full quieting when I did this. I can't
help but wonder how much difference it will make with the mobiles.

Thanks for the comments.

Buck
N4PGW

 
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