Let me clarify this statement so that we are on the same page.
I was hearing several conversations going on the same frequency. Those
conversing obviously were oblivious to other users on the frequency because
of propergation or the peculiarities of my antenna.
I refrained from entering into conversation with the local group because by
joining one group would have caused problems for other groups on the same
frequency.
On reflection it would appear that the horizontal dipole gave low angle TOA
all the way thru 90 degrees.
Thus this is inferior to a vertical that captures the low angles and
descriminates against the high angles plus inferior to a poor vertical that
discriminates against low angles.
This just shows how much ground effect controls the
verticals but only to a much lower extent on horizontally polarised signals
with respect to selectivity.With respect to noise it does not affect me to
much in the comparison because of the use of a Faraday shield.
Regards
Art
"Art Unwin KB9MZ" wrote in message
m...
"Reg Edwards" wrote in message
...
Incoming radiation angles can be obtained by geometric calculation.
Pythagorus and all that, taking earth curvature, height of ionospheric
layers, number of hops, etc, etc, into account.


Then point your receiving beam into it, if it is adjustable in the
vertical
plane. Very non-critical. Antenna apperture angles in the vertical
plane
are extremely broad.


The stuff often comes in from more than one angle. Interference between
the
different paths causes fading and distortion. An antenna will collect
from
all vertical angles regardles of elevation.
----
Reg

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



Interesting thing happened with the antenna last night.
Had the antenna in the vertical position close to ground ( it is a
truncated co linear dipole) And was prevented from joining the local
group because of multiple QSOs on the same frequency!

Art

" Art Unwin KB9MZ" wrote in message news:acKJb.51720$xX.290427@attbi_s02...
Let me clarify this statement so that we are on the same page.

On reflection it would appear that the horizontal dipole gave low angle TOA
all the way thru 90 degrees.

??? 90 degrees is straight up. NO low horizontal dipole will have very
good low angle performance on that band. Trust me. I used a full size
Z dipole for two years,"01-02" and ended up yanking it down. Good for
close in local stuff. Pitiful for lower angle far off stuff.

Thus this is inferior to a vertical that captures the low angles and
descriminates against the high angles plus inferior to a poor vertical that
discriminates against low angles.

How is it inferior? It's just different. You choose the antenna to
match the path you want to work. If you are going to talk 100-150
miles away, yes a low dipole will work pretty well, maybe the best.
But so will an inv L, or even my top loaded vertical will usually do
fine also. The L will usually be the better of the verticals close if
it's up and down sky wave, as it has more horizontal componant. My
loaded vertical has an overhead null.
Even still, many times, even just 200 miles away, my loaded vertical
is better than the L. Actually, the loaded vertical beats the L
probably 90% of the time. Even fairly close. Farther off paths? The
dipoles I had were poor at best. The vertical is the only way to go in
that case for a simple antenna. Remember, my dipole was at maybe 35-40
ft. Thats like a 80m dipole at 15-20 ft off the ground. Will be poor
for long distance use. Of course, using ground wave, the loaded
vertical is king of the hill here...

This just shows how much ground effect controls the
verticals but only to a much lower extent on horizontally polarised signals
with respect to selectivity.

??
With respect to noise it does not affect me to
much in the comparison because of the use of a Faraday shield.

?? Shield for what? You? MK

Art, KB9MZ wrote:
"Thus this is inferior to a vertical that captures the low angles and
discriminates against the high angles plus inferior to a poor vertical
that discriminates against low angles."

Yes, a vertical discriminates against high angles as it has a null in
its pattern overhead.
What "poor vertical" discriminates against low angles if ground
conductivity is OK? A too-short vertical still has maximum radiation
toward the horizon though it has less than a 1/4-wave or 5/8-wave
vertical antenna has.

Best regards, Richard Harrison, KB5WZI

Yuri, K3BU wrote:
"Recent studies found efficiency of various polarizations based on
geographical location, related to geomagnetic fields (gyrofrequency).

Do antenna modelimg programs adjust for gyrofrequencies? I can readily
see that soil conductivity at a geographical location would affect
efficiency and perhaps the polarization choice.

John H. Nelson, RCA Short-Wave Radio Propagation Analyst, found that
those signals which pass through or close to the auroral zone suffer the
greatest degradation. If the signal must take a great circle route over
the North Polar region, problems increase.

Nelson also found that propagation here on the earth correlated with the
relative positions of the planets in the solar system. Be this astronomy
or astrology, it allowed Nelson to make pretty good radio propagation
forecasts. See: "The Propagation Wizard`s Handbook", a "73" publication
by J.H. Nelson.

Best regards, Richard Harrison, KB5WZI

On Sat, 3 Jan 2004 10:35:51 -0600 (CST),
(Richard Harrison) wrote:

If the signal must take a great circle route over
the North Polar region, problems increase.

Hi Richard,

This is a S+N/N problem, not propagation. It is not like the magnetic
pole is sucking signals into the ground. What the pole IS attracting
is the ionic flow from the sun's emissions which create a plasma of
noise.

73's
Richard Clark, KB7QHC

This is a S+N/N problem, not propagation. It is not like the magnetic
pole is sucking signals into the ground. What the pole IS attracting
is the ionic flow from the sun's emissions which create a plasma of
noise.

73's
Richard Clark, KB7QHC



On 160 and 80 during disturbed conditions (aurora, etc.) signals are skewed by
as much as 90 deg from their short path directions. So it is not sucking but
blowing signals away from the disturbed region. Maybe sucking too, I haven't
been up there to see it. It is not just noise problem.
Some outrageous propagation stuff is in my old article at
http://members.aol.com/ve3bmv/bmvpropagation.htm

Yuri, K3BU, VE3BMV

When both antennas have about the same height at their centres -


A half-wave vertical is better at low elevation angles.


A half-wave horizontal dipole is better at high elevation angles.


There's nothing at all to choose between them at 45 degrees.


For each of the following factors allow a predicting uncertainty of +/- 1/2
S-unit -


MF, HF, sun-spot cycle numbers, day, night, summer, winter, aurora, N/S,
E/W, giro-magnetic disturbances, high-rise city centers, arid deserts, the
oceans, mountain ranges, prairies, pampas, steppes, tropics, arctic
regions, G5RV's and unsociable noisy neighbours.


Use RMS summation of predicting uncertainties.


If you are using Roy's S-meter calibration multiply by 2. ;o)


And that just about sums it up.
----
Reg, G4FGQ

--
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........
"Richard Clark" wrote in message
...
On Sat, 3 Jan 2004 10:35:51 -0600 (CST),
(Richard Harrison) wrote:

If the signal must take a great circle route over
the North Polar region, problems increase.

Hi Richard,

This is a S+N/N problem, not propagation. It is not like the magnetic
pole is sucking signals into the ground. What the pole IS attracting
is the ionic flow from the sun's emissions which create a plasma of
noise.

73's
Richard Clark, KB7QHC