Roy, W7EL wrote:
"So you`ve improved your transmit effectiveness but haven`t improved
your ability to receive."

Exactly, for Roy`s mpre radials under a vertical antenna.

For horizontal antennas, it`s another matter. The horizontal
discriminates against vertically polarized signals. Both polarizations
result from ionospheric reflection of a signal of either polarization.
The most annoying noise usually originates locally and travels to the
receibver by a vertically polarized wave, the only polarization
propagated by a ground wave.

A horizontal antenna is insensitive to vertically polarized waves, so
improving its efficiency possibly improves reception of horizontally
polarized waves without a corresponding increase in noise reception.

I worked for years in a system which relayed its broadcast programs by
HF radio. This was before satellites, jets, and great recording quality.
We also needed immediate relay capability for breaking news. All HF
relay systems were horizontally polarized.

Best regards, Richard Harrison, KB5WZI

Thing is....So did my model when using "medium" ground quality.
But I know in the real world, my vertical smoked the dipole on long
haul/low angles. I'm almost positive that the verticals are
"underpowered" when
modeling, unless you bump up the ground quality. Or at least when used
on the low bands at night. To make the model of my dipole vs vertical
actually pan out as in real life, I had to bump up the ground quality
to
"excellent". Even then, it might have been a bit lower than real life.
I'm not sure what to make if this....
I'm not the only one to notice this also.... Talk to W8JI about his
nearly
300 ft dipole vs his verticals on 160m...He always thought the dipole
would be
better. After all, modeling says it should be. But it didn't quite pan
out...
I basically ignore Cecils bad experience, because #1, his vertical
needed more radials,
and he never used it for long haul paths. So of course, the vertical
should
have lost in his case. Heck, even with my vertical, that was a bit
better than his,
I had to get over 1000 miles to start seeing the vertical overtake the
dipole.
Those dipole vs vertical modeling plots are *very* misleading. Or to me
anyway...
Myself, I think the ground qualities applied are in error for some
reason..
They overly stunt the vertical when modeling...Either that, or my
ground here is
really good...My ground quality is pretty good, but it's not *great*,
being I'm
in the city cement jungle of Houston. MK

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

On 30 Jan 2005 15:00:33 -0800, wrote:

Either that, or my ground here is
really good...My ground quality is pretty good, but it's not *great*,
being I'm in the city cement jungle of Houston. MK

Hi Mark,

Actually, according to the FCC ground conductivity map, you are very
well situated sitting on very good to exceptionally good soil (as you
look towards the Gulf) which is 4 to 16 times better than my own here
in Rain City.

73's
Richard Clark, KB7QHC

All HF relay systems were horizontally polarized.....

I wonder about the time of day and freq? I'd almost bet many were in
the daytime,
and using fairly high frequencies as far as HF. IE: 31,25,19 m, etc...
Seems the choice was as much a receiving/noise consideration rather
than absolute
signal strength.
I think the choice is much more complex than any theoretical gains seen
in modeling,
ect. In the daytime, I don't think it really matters much. So in that
case, it
would probably make sense to use horizontal to reduce local noise
pickup. That
would improve the receive s/n. As far as transmit strength, probably
not a whole
lot of difference either way.
But at night, it seems to be a different ballgame. I think the
differences in
propagation skew things towards the vertical on the low bands at night.

The farther the path, the better the advantage.
It could be stated that most horizontal wire antennas are lower to the
ground in
terms of wavelength on those bands. This is true. But you still have
cases where
people have tried the high antennas on the low bands, and still see the
verticals
usually win on long paths.
I've never tried it, but any interested could model my 36 ft high
dipole, and then
model my 10 ft center loaded mobile whip, on a ford truck.
I'd almost bet the dipole creams the mobile antenna in the model at low
angles
as far as the gain numbers shown.
But I know in the real world, that mobile beats the 36 ft high dipole
from Houston
to Jacksonville Fla at 2 AM. Yes, even I was surprised the first time I
saw it.
But I tried it over, and over again, and it was not a fluke of nature.
If you could have two 160/80/40 m antennas at 1 wave up, both with the
same exact
gain, IE: one a 1/2 wave vertical with any radials needed to equal the
ground loss
of a horizontal dipole, I'd bet money the vertical would win on long
paths 95% of
the time. It's not just a pure "gain" thing.... I think even verticals
with less gain
will win over the dipoles once the path becomes long enough. Note my
mobile...
I know for a fact from real life, if you are going to run a dipole, and
expect to
equal my 36 ft high ground plane, you better plant that puppy *WAY*
high, or you won't
have a chance. I'm talking over a 1/2 wave up. More like a full wave,
and even then
you might lose, once the path gets to about 4k or so...
BTW, these days in Houston, local noise has just as good a chance being
horizontal
as vertical...Most is powerline noise...So with my vertical, I never
really noticed
any extra noise. The s/n ratio was always better on the vertical, for
long haul.
IE: if the noise comes up 1 s unit, but the desired signal 2 s units,
the noise
is a non factor...Many times I saw no extra noise on the vertical.
MK

Well...Depends on what part of town...On the coast, it's great. A 30...
But in town, they rate it as about a 15. But that would vary greatly
I'm
sure...I'm in a suburban area, so I might be maybe a "20" ???
I know that I had very mediocre results using ground mounted verticals.
I had one with 32 full length radials, and it was poor compared to my
ground plane at 36 ft, with 4 radials. It was probably about as good as
Cecils vertical he ran....LOL...:/ MK

On 30 Jan 2005 16:51:17 -0800, wrote:

Well...Depends on what part of town...On the coast, it's great. A 30...
But in town, they rate it as about a 15. But that would vary greatly
I'm
sure...I'm in a suburban area, so I might be maybe a "20" ???
I know that I had very mediocre results using ground mounted verticals.
I had one with 32 full length radials, and it was poor compared to my
ground plane at 36 ft, with 4 radials. It was probably about as good as
Cecils vertical he ran....LOL...:/ MK

Hi Mark,

You have to think deeper into the ground than the thickness of
concrete or asphalt. Unless the project developer scraped off the top
6 feet and dumped it into Galveston Bay for fill, and then backfilled
your neighborhood with industrial waste.... RF and your antenna is
looking at a BIG foot print below it from your antenna's elevation
(probably a greater boon than ground mounted - your experience seems
to support this).

This means that when your RF first strikes earth at a DX angle of 5 to
10 degrees, it is a vastly bigger surface than that seen with a ground
mount because that ray strikes further away. (About half a mile away,
if I did my Trig right.) Instead of illuminating your driveway and
street, the elevated vertical is lighting up 100s of acres that
averages the ground conductivity over lawns, streets, gardens, homes,
lots....

Off hand, I would say the modeler with higher ground settings is
validated by your experience and conforms to your environment.

73's
Richard Clark, KB7QHC

Gary Schafer wrote:
Sometimes right hand was best sometimes left hand was best.

Indicating that, for a single antenna, polarization doesn't
much matter for HF skip since it is continuously changing.
--
73, Cecil http://www.qsl.net/w5dxp


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Mark, NM5K has raised some interesting questions. Time of day and
frequewncy?

We operated almost around the clock with both broadcasting and program
relay. For broadcast, the schedules are based on propagation predictions
and must be published far in advance. The schedule must be followed no
matter how propagation actually turns out. The best likely frequency is
picked for the path. Also scheduled is something in the next lower
frequency band and something in the next higher frequency band. For
program relay, you can make unscheduled frequency adjustments at any
time it is convenient to do so.

Triple space diversity was the method we mostly used. (3) separate
receiving antennas, spaced about 10 wavelengths apart laterally at
40-meters (400 meters) were used to receive all relayed programs. Each
antenna fed a multicoupler so that receivers could be connected without
interaction.

The three receivers tuned to a particular program (not necessarily the
same frequency) had their outputs fed to a single TDR combiner (Crosby
or Pioneer). The combiner accepted the best output of the three
receivers and rejected the other two. An operator checked the reception
regularly to see if the signal could be improved by selection of either
the upper or lower sideband, or other means.

The height of the antennas was about 20 meters. High enough for
single-hop propagation over the path at midday on the 20-meter band. We
had fixed height so it had to serve from 5 MHz to 18 MHz at all hours.
For relay, we adjusted frequencies almost 24-hours to pick those
frequencies which were working best at the time and might also be
transmitting in the next higher and/or lower band during changing
conditions For relay we used 3 to 5 KW. For broadcast we used 50 KW and
100 KW. Antennas had about 15 dBd gain on both relay path ends. For
broadcast we used 15 dBd gain on the transmitter. The receiver may have
had a wet noodle for an antenna. If it was good enough for the jammers
it was probably good enough to receive us too.

Mark also wrote:
"I`d bet money the vertical would win on the long paths 95% of the
time."

The vertical has its null directly overhead, and it has its maximum
radiation at low vertical angles from the horizontal. A hazard for the
vertical is low uncorrected soil conductivity benearh the antenna.

Put the horizontal antenna up high and it works with either low
conductivity or high conductivity soils. Low height is the hazard for
the horizontal antenna if you want DX.

Best regards, Richard Harrison, KB5WZI

Hummm. Maybe that explains the large difference I saw between it and
the ground
mount. I know the antenna seemed to really come alive once it's up
about a 1/4
wave. I never was too crazy about ground mount verticals. To me, it's
like
ground mounting a dipole...Makes about the same sense....Of course, the
GP may
not be for everyone...Not really hard to put up, but it's a 68 ft tall
antenna,
the way I had it installed. I took it down a couple of summers ago,
because the
lightning had been so bad. Was paranoid I'd take a hit eventually...It
was
boom-boom every day at that time...It's now resting on the side of the
house..
MK