Reg, G4FGQ wrote:
"On the other hand, a simple vertical does reasonably well when working
just across country because of the short propagation path, almost
straight up and down again, even via the groundwave for a very short
distance."

True, but the thread is: "Verticals versus Horizontal Dipoles". Reg`s
choice, I think.

Verticals have a null toward the zenith which tends to impair their
"straight up and down again" performance. The horizontal dipole`s nulls
are at its tips, too, but are pointed elsewhere, not at the zenith. This
mey actually avoid some noise and interference beyond that originating
in the directions of straight up or down again. As much noise is
vertically polarized, it may be rejected by ctoss-polarization.

The horizontal dipole performs pretty well in the directions near the
zenith when it is elevated at less than 1/2-wavelength in height, and
for frequencies below the maximum usable frequency at near vertical
incidence. At 1/2-wavelength elevation, the horizondal dipole develops a
null toward the zenith, too.

Propagation of H-F signals via the groundwave is for a very short
distance indeed. Frequency has a pronounced effect upon sffective earth
conductivity. Conductivity falls fast with increasing frequency due to
skin effect. . The earth layer penetrated by the wave thins as frequency
increases, making it less conductive and increases loss. For example,
over soil of 10 mmhos/m, a fairly common value, a transmitter would have
to ptoduce 1,000 times more power at 5 MHz to produce the same signal at
10 miles as would a 0.5 MHz transmitter.

The earth`s attenuation of low-angle radiation from a 1/4-wave vertical
antenna has a significant effect on the vertical radiation pattern. ee
Fig. 54-1 on page 465 of B. Whitfield Griffith`s "Radio-Electronic
Transmission Fundamentals". This figure shows field intensity curves
versus vertical angle from a 1/4-wave vertical antenna radiating 1
kilowatt over earth of average conductivity. Anything below about
5-degrees is gone, eaten by the earth`s losses.

I conclude that for high frequencies, unless you have good or very good
conductivity soil, horizontal polarization will likely serve you better
than vertical polarization.

If you are at sea or immediately on the sea shore, you likely may do
better with vertical polarization.

There are so many variables that it would likely be best to have
antennas of both polarizations available, and to use the antenna which
gave the best signal in the particular instance.

Best regards, Richard Harrison, KB5WZI

This is an early stage of the experiment, but
I believe that there is a lot to say with the lower noise on the
horizontal antenna station

Probably has a lot to do with the particular sites
though. It's quite possible to be near a noise source
that is mainly vertical polarized. In a case like that, it's
possible it could be a problem. But I never saw the difference
in noise levels you are seeing. At the worst, I might see
appx 2 S units, but sometimes it might only be one, or
even other times , nearly no difference at all. Most of
the noise I would see at this location is power line noise.
It seems to effect both horizontal and vertical nearly equally.
Probably cuz much is radiated by horizontal power lines.
I've never tested it, but I think if you are in a noiseless location,
the difference would be fairly small as far as meter readings
just measuring the average atmospheric noise. The reason I
say this is because sometimes I would see little difference in
noise between the two. But other times I might see more.
But you could see small differences just from the increase in
strength of dx signals. IE: if you had T-storms 1500 miles away,
it's quite likely the vertical will receive them stronger than the
horizontal due to the normal operation of the antennas.
Anyway, I don't totally consider what you see as the norm. "4 s units"
You probably have a local vertical noise source nearby. If it's power
line, etc, you might be able to track it down and get it fixed.
I'd be curious to see if you see the same 4 S unit noise difference
over a period of time. Like I say, mine would vary. But noise
never was much of a concern on mine. Never gave it much thought
at all. Kinda weird too being I'm in a big city, in a residential area.

Being mine was elevated at 36 ft at the base, I also had a pretty
good line of sight to any potential noise sources.
The tip of the radiator was at about 68 ft. As far as the VE being
better on the wire, that's probably fairly normal, being he wasn't dx.

Also, as a final note, while your butternut with 20 radials is ok, it
still
isn't quite up to the performance I saw with mine at 36 ft, using a
full size antenna. So I saw a larger signal increase on the dx than you

I bet. Mine was appx equal to a full length monopole with 60 radials,
if ground mounted. I'd have to look, but my ground may be a bit better
too. I'm right on the edge of being in a "30" zone. Of course, raising
efficiency raises s/n equally, but I noticed that I never saw the same
performance I had with the ground plane, when I ran the same full size
vertical on the ground with 32 radials. That antenna was about equal
to my dipoles at 1500 miles. Maybe a small bit better, but not any
2 S units worth like the GP was. So regardless of some saying the
number of radials is not too important, it must be, if you want the
best
performance. Sure made a difference here...
Either that, or elevating it above the surroundings makes the
difference.
Myself, I think it's about 75% the first, and 25% the second...
Elevating
the antenna for sure increased my local ground wave. I could work 50
miles away ground wave easy. I'd have cases in the daytime where I'd
lose locals due to the band stretching out. But I could still nail them
at
S 9 using the GP, where the dipole would be hard to read backscatter.
Of course, if the band was open short, I'd be 10-20-30 over 9 on the
dipole
to the same location.
Anyway, I guess you gotta use what works, but I don't think it's
totally
normal to see a huge difference in noise between vertical and
horizontal
unless something local is the culprit.
MK

"Richard Harrison" wrote:
The earth`s attenuation of low-angle radiation from a 1/4-wave vertical
antenna has a significant effect on the vertical radiation pattern. ee
Fig. 54-1 on page 465 of B. Whitfield Griffith`s "Radio-Electronic
Transmission Fundamentals". This figure shows field intensity curves
versus vertical angle from a 1/4-wave vertical antenna radiating 1
kilowatt over earth of average conductivity. Anything below about
5-degrees is gone, eaten by the earth`s losses.
________________

This certainly is not true for frequencies below about 2 MHz. If it was
true, MW broadcast stations would have no groundwave coverage -- which of
course is the only useful coverage they _do_ have in the daytime.

A monopole vertical radiator of any length up to 5/8-wave, when used with a
ground system of ~120 buried radials each ~1/2-wave long, radiates its peak
field very nearly in the horizontal plane regardless of the conductivity of
the ground in which the radials are buried. This gain is within a few
percent of the theoretical peak gain for these radiators when working
against an infinite, perfectly conducting ground plane, as was demonstrated
by the field tests of Brown, Lewis & Epstein in 1937. This principle has
been accepted and used by the FCC and other regulating agencies, and has
been field-proven in thousands of installations going back many decades.

Once "launched," the groundwave signal is affected by ground conductivity
along the propagation path, earth curvature, obstructions etc. Groundwave
path loss increases with increasing frequency, and above some frequency in
the low HF range, the groundwave is unable to serve a practical purpose.
But that doesn't necessarily mean that the transmit antenna did not generate
the groundwave in the first place, ie, that it radiated zero field in the
horizontal plane and at very low elevation angles.

RF

Visit http://rfry.org for FM transmission system papers.

My geometric argument that beyond distances of several hundred,
perhaps 500 miles, the vertical puts down a stronger signal and
receives stronger signals than the horizontal dipole cannot be
disputed.

If you can't be heard at 1000 miles or more using a dipole, you are
more likely to be heard using a vertical regardless of what antenna
the other fellow is using to receive. At great distances you are much
more likely to be heard using a vertical at the same average height
above its surroundings.

Signal to noise ratio does matter of course.

Local noise level is much greater than received from distance sources
for obvious reasons. Local noise is vertically polarised. It comes in
via groundwave.

Noise from a distance is randomly polarised. It comes in via the
ionosphere. So in towns and cities, with buildings wiring, overhead
power and phone lines, where most of us live, the vertical collects
more local noise. In the wide open countryside both types of antenna
tend to perform equally well on randomly polarised, distant noise
levels.

With distant noise and interference and distant signals, both types of
antenna result in the same signal to noise ratio in the receiver. But
the vertical antenna receives the stronger signal plus noise. If the
internal receiver noise is greater than the received signal plus noise
then the vertical antenna will win the contest.

However, there is another effect which sometimes gives the dipole the
advantage. It is multi-hop propagation.

The angle of elevation of the radio path increases with the number of
hops involved. The number of hops depends on the sun-angle and day or
nighttime. Across the States or across the Pacific, for example, the
propagation loss can be much less with 2 or 3 hops than it is with one
or two hops. Waves sometimes bounce between the F2 and E layers. The
increase in elevation angle favours the horizontal dipole. And how
many amateurs know the number of hops involved at any point in time?

But what eventually favours the vertical over the dipole is their
respective service areas. The service area covered by the vertical is
many times, far greater than the dipole and so is the world wide
distribution of radio amateurs and short-wave listeners.

We have now returned to the simplistic but precise Geometry of the
ancient Egyptians and Greeks. ;o)
----
Reg, G4FGQ.

"Reg Edwards" wrote:
The low-angle performance of a half-wave dipole, even when
radiating broadside towards the receiver, is very poor in
comparison with a simple vertical.
________________

To the extent that this is true, it is not just a function of the intrinsic
radiation patterns of the (horizontally polarised) half-wave dipole and the
vertical monopole, but also to the net gain toward the other end of the path
including reflections of that intrinsic radiation from the physical
environment around the antenna.

The performance of an antenna near the earth can depend as much on its
installation conditions as its free space pattern.

RF

"Richard Fry" wrote in message
...
"Richard Harrison" wrote:
The earth`s attenuation of low-angle radiation from a 1/4-wave
vertical
antenna has a significant effect on the vertical radiation
pattern. ee
Fig. 54-1 on page 465 of B. Whitfield Griffith`s "Radio-Electronic
Transmission Fundamentals". This figure shows field intensity
curves
versus vertical angle from a 1/4-wave vertical antenna radiating 1
kilowatt over earth of average conductivity. Anything below about
5-degrees is gone, eaten by the earth`s losses.
________________

This certainly is not true for frequencies below about 2 MHz. If it
was
true, MW broadcast stations would have no groundwave coverage --
which of
course is the only useful coverage they _do_ have in the daytime.

A monopole vertical radiator of any length up to 5/8-wave, when used
with a
ground system of ~120 buried radials each ~1/2-wave long, radiates
its peak
field very nearly in the horizontal plane regardless of the
conductivity of
the ground in which the radials are buried. This gain is within a
few
percent of the theoretical peak gain for these radiators when
working
against an infinite, perfectly conducting ground plane, as was
demonstrated
by the field tests of Brown, Lewis & Epstein in 1937. This
principle has
been accepted and used by the FCC and other regulating agencies, and
has
been field-proven in thousands of installations going back many
decades.

Once "launched," the groundwave signal is affected by ground
conductivity
along the propagation path, earth curvature, obstructions etc.
Groundwave
path loss increases with increasing frequency, and above some
frequency in
the low HF range, the groundwave is unable to serve a practical
purpose.
But that doesn't necessarily mean that the transmit antenna did not
generate
the groundwave in the first place, ie, that it radiated zero field
in the
horizontal plane and at very low elevation angles.

==========================================

Rich, all what you say is quite true - except that groundwave is
radiated at ALL frequencies from a vertical of 5/8-wave or shorter.

Useful propagation occurs at 30 MHz and below. But loss in the ground
and loss due to obstructions above 1/4-wave in height is high. Solid
ragchews across town and small city are quite possible on the 10m
band.

For predicting groundwave propagation from VLF to HF, download program
GRNDWAV3 from website below.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

For predicting groundwave propagation from VLF to HF, download
program
GRNDWAV3 from website below.

======================================

Sorry, I should have said download program GRNDWAV4 from website
below.
----
.................................................. ...........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

Hi Reg

Interesting stuff

I wonder however if you have any hard data on the merits of using one
polarization over another in an electrically noisy environment. For
years I have believed (but never seen proof) that on average horizontal
is better for this.

Any comments? If it is horiz, why? Is it indeed the high radiation angle
missing local noise makers or something else..?

Cheers Bob VK2YQA

Reg Edwards wrote:
There is much discussion about the relative merits of the simple
vertical versus horizontal dipole antennas.

Interesting stuff

I wonder however if you have any hard data on the merits of using
one
polarization over another in an electrically noisy environment. For
years I have believed (but never seen proof) that on average
horizontal
is better for this.

Any comments? If it is horiz, why? Is it indeed the high radiation
angle
missing local noise makers or something else..?

Cheers Bob VK2YQA

Reg Edwards wrote:
There is much discussion about the relative merits of the simple
vertical versus horizontal dipole antennas.

==========================================

Local noise is stronger in terms of milli-volts per meter than distant
noise for obvious reasons. It is nearer and man-made.

Local noise is vertically polarised and comes in via the groundwave
and at low elevation angles.

Therfore, a vertical antenna which is most sensitive to vertical
polarisation and to signals and noise coming from low angles produces
greater low-angle signals and low-angle noise in the receiver.

Whereas, distant noise comes in from high angles via the ionosphere
and is randomly polarised. It is weaker than local noise. It depends
on lattitude, the sun, day or night and season of the year.

Therefore, a horizontal dipole which is most sensitive to signals and
noise coming in from the higher angles produces greater high-angle
signals and high-angle noise in the receiver.

Now carry on from there. Compare a dipole receiving a low-angle
signal with high-angle noise coming in from all directions, with a
vertical antenna receiving a high-angle signal with low-angle noise
coming in from all directions.
----
Reg.

"Reg Edwards" wrote in news:drqije$rqq$1
@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com:

Opinions of the many individuals depend on geographic lattitude, World
population densities, what bands happen to be favourites, G5RV's and
how much money there is in the bank. Let's try to remove these
distracting factors.

I'll put it in somewhat different "simplistic" terms.

Everything else being equal, the deciding factors are geometry and
trigonometry. The performance of a dipole is better at elevation
angles greater than about 45 degrees and the performance of a vertical
is better at lower angles. That's because the vertical and horizontal
antenna types are oriented at 90 degrees to each other. At elevation
angles around 45 degrees performance is about the same for both types.

No, at 45 degrees the PATTERN is about the same (assuming that the
horizontal antenna is at least .25 wavelength high). But the actual GAIN
over an isotropic source is equivalent down at around 25 degrees. That's
because the vertical is normally a monopole, the other half of which is
reflected in the ground, whereas the dipole is a dipole and its ground
reflection is therefore another dipole stacked with it. Ground losses
for the dipole occur at a lower incident angle and further from the
antenna and are thus lower.

Of course, you can have the best of both worlds by using a vertical
dipole, in which case your take-off angle will really be quite low.

The main reason why verticals tend to outperform dipoles on low-band DX
paths is that the dipoles and other horizontally polarized wires are
rarely very high. A lot of them are only about an eighth of a wavelength
up or even less. This increases ground losses at all angles and reduces
the efficiency of the antenna. And if you can get the current loop to
climb up the antenna (by top loading it), a vertical will compete very
strongly below about 30 degrees.


--
Dave Oldridge+
ICQ 1800667