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

--
Buck
N4PGW

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

On Sat, 29 Jan 2005 18:41:35 -0800, Roy Lewallen
wrote:

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.

Thanks. My determining factor will be making the contact when I am up
for it. Too many times I have heard an s5 or better signal but by the
time it was my turn to call, or the pileup dies down, I can't hear the
mobile. That may be the answer.

I once considered phasing the vertical and horizontal together, but
from everything I read, the advantages of one over the other often
have to do with noise not picked up due to polarity. Horizontals have
some noise, and verticals have different noise, but a combination of
the two would have it all.

Since I am dealing with 20 and 40 meters mostly, I would only concern
myself with the 20 meter vertical. 40 doesn't seem to have the
problem. It seems that if I hear them on 40 I can work them. On 20 I
might get a 5-7 reply to a 22 report or vice-versa.

If I hang the vertical here, the top will be about 65 feet above
ground. The dipole feedline will be about 15 feet away and the center
of the dipole about 50-55 feet high. I doubt they will interact with
each other.


Thanks for your comments.

--
Buck
N4PGW

Roy Lewallen wrote:
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.

Thats pretty close...They flip flop back and forth...

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

Depends on the length of the path, and the frequency. On 40m at night,
the
improvement using the vertical is spectacular *if* the path is long
enough.
But that will vary. At 500 miles, usually the dipole will win.
At 1000 miles, usually they will be about even. At 1500 miles the usual
amount
on the S meter is about 2 s units in favor of the vertical. At 4000+
miles,
can be 4 s units.
But of course, this will vary to the quality of the vertical.
In my case, was a full size ground plane, 4 radials, up 36 feet at the
base.
The dipole was at 36 feet. Same height as the base of the GP.
My 40 meter mobile antenna is almost always better than my 36 ft high
dipole
to either of the coasts. I've tested that many times to Fla.
On say a 1500 mile path, usually the vertical will hold the best
overall,
maybe 90 percent of the time, but you will see the shift where they
flip flop
for a short time, and then flip back...
Sometimes the flop will leave them about equal. When back to "normal",
the vertical will be noticably better..2 s units in that 1500 mile
case...The vertical will be better a lot larger percentage of the time,
than
the dipole. I've seen many cases where the dipole never is as loud as
the
vertical, no matter what the shift...But thats usually on the longer
paths.
The longer the path, the larger the vertical advantage. To say VK land,
I've
never seen the vertical less than 3-4 s units better than the dipole at
36 ft.
And I was on about 3 times a week to check at that time. That dipole
would have
to be a whole lot higher than 36 ft to even come close to the ground
plane I ran.

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.

True...I make no claim to actual db increase....But I do use switches,
and get
a good A/B comparison...BTW...I think the vertical advantage on long
paths
decreases as you go higher in frequency...Maybe cuz the dipoles are
higher in
wavelength??? Not sure...Seems to be more a lower band, nighttime
thing...The
types of propagation at night vs day may be a factor...MK

From URL:
http://www.astronantennas.com/polarization.html

On line-of-sight (LOS) paths, it is most important that the polarization of
the antennas at both ends of the path use the same polarization. In a
linearly polarized system, a misalignment of polarization of 45 degrees will
degrade the signal up to 3 dB and if misaligned 90 degrees the attenuation
can be 20 dB or more.

--
Caveat Lector



"Buck" wrote in message
...
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

--
Buck
N4PGW

Buck wrote:
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.

2m signals don't bounce off the ionosphere. It is not clear what
band you are talking about. For sky wave communications on HF, the
polarization doesn't much matter. For ground wave communications,
polarization matters.
--
73, Cecil http://www.qsl.net/w5dxp



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On Sun, 30 Jan 2005 12:56:05 -0600, Cecil Moore
wrote:

2m signals don't bounce off the ionosphere. It is not clear what
band you are talking about. For sky wave communications on HF, the
polarization doesn't much matter. For ground wave communications,
polarization matters.
--
73, Cecil http://www.qsl.net/w5dxp


Primarily 20 meters, maybe 40 meters.

Thanks

--
Buck
N4PGW

On Sun, 30 Jan 2005 12:56:05 -0600, Cecil Moore
wrote:

Buck wrote:
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.

2m signals don't bounce off the ionosphere. It is not clear what
band you are talking about. For sky wave communications on HF, the
polarization doesn't much matter. For ground wave communications,
polarization matters.

A couple of years ago I was keeping a sked with a friend on 10 meters.
The path was about 1800 miles. I mounted a vertical element on the end
of the 3 element beams boom. I wanted to try circular polarization. By
using proper feed line lengths and switches I could switch between
right or left hand circular polarization. The beam had a little more
gain than the single vertical element but the effects were dramatic at
times.

Sometimes right hand was best sometimes left hand was best.

But what turned out to be interesting was when both vertical and
horizontal where in phase and connected together. It lowered overall
signal strength a little but the fading was much less.

At times signals would fade deeply on either vertical or horizontal
polarization. Circular helped a lot but the signal kept changing
between left hand and right hand so you had to keep flipping the
switch.

With both antennas in phase it would receive vertical or horizontal
without changing anything. Very smooth constant signal.

At other times just the beam was better alone.

Transmit appeared to benefit the same. He could hear me with less
fading with the in phase antennas as well. My friend on the other end
only had horizontal polarization. He was going to try a vertical
element too but never got to do it before 10 meters died.

73
Gary k4FMX