30m should certainly be well within the range of the "universal"
dipole design.

Presumably the gain/beamwidth numbers you quote come out of
a model. For completeness, what does the model say the average
gain is in the OTHER 180 degrees (the nulls)?

73, Ed


"Cecil Moore" wrote in message
...
KC1DI wrote:
Just curious as to what most of you are using as an antenna on
the 30 Meter band?

My 130 ft. center-fed dipole has an interesting pattern on 30m. It's
main lobes are broadside with a gain of 9 dBi, a TOA of 34 deg, and
a horizontal beamwidth of 33 deg. Off the ends, the gain is 3 dBi
with a horizontal beamwidth of 60 deg. In other words, it has gain
over a ground mounted quarter-wave monopole in 4 directions for more
than 180 degrees of the horizontal.
--
73, Cecil http://www.qsl.net/w5dxp

Old Ed wrote:

30m should certainly be well within the range of the "universal"
dipole design.

Presumably the gain/beamwidth numbers you quote come out of
a model. For completeness, what does the model say the average
gain is in the OTHER 180 degrees (the nulls)?

60 degrees of the horizontal coverage falls below the typical
1/4WL ground-mounted monopole - not a bad tradeoff, IMO.
--
73, Cecil http://www.qsl.net/w5dxp



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Hi again Cecil, and thank you for responding!

But since you answered a different question than the one I asked,
I'll follow up with a few more questions.

Are the model comparisons based on power applied to the antenna
feedpoint, independent of feedline and/or tuner losses?

What height and ground conditions are you modeling for the dipole?

What radial structure are you assuming for the "typical 1/4WL
ground-mounted monopole?"

What ground conditions are you assuming for the "typical 1/4WL
ground-mounted monopole?"

What is the best (read highest average gain) elevation angle for the
dipole under the assumed conditions?

What is the best elevation angle (read highest average gain) for the
monopole under the assumed conditions?

At what elevation angle(s) are the modeled patterns being compared?

73, Ed

"Cecil Moore" wrote in message
...
Old Ed wrote:

30m should certainly be well within the range of the "universal"
dipole design.

Presumably the gain/beamwidth numbers you quote come out of
a model. For completeness, what does the model say the average
gain is in the OTHER 180 degrees (the nulls)?

60 degrees of the horizontal coverage falls below the typical
1/4WL ground-mounted monopole - not a bad tradeoff, IMO.
--
73, Cecil http://www.qsl.net/w5dxp

Old Ed wrote:
Are the model comparisons based on power applied to the antenna
feedpoint, independent of feedline and/or tuner losses?

Yes (However, for A-B comparisons, the dipole used a tuned feeder
and no tuner. The vertical was fed with RG-213 and no tuner.)

What height and ground conditions are you modeling for the dipole?

It's my typical East Texas ground at a height of 40 ft.

What radial structure are you assuming for the "typical 1/4WL
ground-mounted monopole?"

8 radials, modeled one foot above ground. A-B tests were done with
8 radials 20 ft above ground sloping down to 6 feet above ground.

What ground conditions are you assuming for the "typical 1/4WL
ground-mounted monopole?"

Typical East Texas ground, same as for the dipole

What is the best (read highest average gain) elevation angle for the
dipole under the assumed conditions?

9 dBi at 34 degrees, 8.5 dBi at 26 degrees, 0 dBi at 7 degrees

What is the best elevation angle (read highest average gain) for the
monopole under the assumed conditions?

-0.65 dBi at 34 degrees, 0 dBi at 26 degrees, -4.5 dBi at 7 degrees

At what elevation angle(s) are the modeled patterns being compared?

See above. The dipole beats the vertical by a couple of S-units in
the dipole's best direction. A-B tests were actually run on 40m.
--
73, Cecil http://www.qsl.net/w5dxp



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Hi Cecil -

Let me again thank you for taking the time to respond to my follow-up
questions! But since the questions you answered are again somewhat
different than the questions I asked, I am going to follow up yet again.

I understand that the monopole pattern is essentially toroidal, and
that the long dipole at 30m produces a more complex, lobed pattern.
The peaks of those lobes have higher gain than the broad, toroidal
pattern of the monopole. No surprises in any of that.

However, neither of these antennas are rotatable. Therefore, there
is no guarantee that either or both will always receive incoming
signals at the most favorable angles. "Average" gain across a range
of angles is therefore very relevant to any comparisons.

If you wouldn't mind exercising your model some more, here are
some questions intended to address the "average" gain topic.
(I'm stressing model results because the type of numbers requested
would be highly impractical to try to measure on the physical
antennas.)

1. At what elevation angle X does the monopole show the highest gain,
and what is that gain?

2. What is the "average" gain of the dipole, at elevation angle X, taken
over the full 360 degrees of azimuth, at one-degree increments?
(Note: Gain data points expressed in dB should be converted to
linear powers, the linear powers averaged, and then the average
linear power converted back to dB, of course. To do otherwise
would improperly penalize a lobed pattern (the dipole) that might
have one or two minus infinity dB gain values.)

3. If you're still on board with all this, it would also be interesting to
know what happens to the elevation angle and gain of the monopole
if the number of radials is kicked up to a large number, like 64.

The validity of the above depends in part on equitable assumptions
about transmission line losses in the two cases, of course.

73, Ed

Old Ed wrote:
1. At what elevation angle X does the monopole show the highest gain,
and what is that gain?

Already answered. If I remember right, it was 0 dBi at 26 degrees.

2. What is the "average" gain of the dipole, at elevation angle X, taken
over the full 360 degrees of azimuth, at one-degree increments?

Please define "average" gain. The reason for using a higher gain antenna
is to increase the gain above an "average" monopole. How about if I just
post the radiation pattern on my web page?

I know where I want to QSO to so I turn my 130' dipole broadside to AZ.

3. If you're still on board with all this, it would also be interesting to
know what happens to the elevation angle and gain of the monopole
if the number of radials is kicked up to a large number, like 64.

It no doubt, goes up. 8 is all I ever installed. Seems to me a waste of
effort to use 32 times the copper that it takes for a dipole and still
not have the gain of a dipole. Incidentally, my 20m-10m dipole is rotatable.
--
73, Cecil http://www.qsl.net/w5dxp



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Hi Cecil, and thanks yet again! Comments below...

"Cecil Moore" wrote in message
...
Old Ed wrote:
1. At what elevation angle X does the monopole show the highest gain,
and what is that gain?

Already answered. If I remember right, it was 0 dBi at 26 degrees.

You quoted the 0 dBi at 26 degrees in an earlier post; but
you did not identify the 26 degrees as the highest-gain angle.


2. What is the "average" gain of the dipole, at elevation angle X,
taken over the full 360 degrees of azimuth, at one-degree
increments?

Please define "average" gain. The reason for using a higher gain antenna
is to increase the gain above an "average" monopole. How about if I just
post the radiation pattern on my web page?

I did provide my definition of average (azimuthal) gain with the question;
but you snipped it out. 8-( Not to worry, I can snip it right back in
again...

"2. What is the "average" gain of the dipole, at elevation angle X, taken
over the full 360 degrees of azimuth, at one-degree increments?
(Note: Gain data points expressed in dB should be converted to
linear powers, the linear powers averaged, and then the average
linear power converted back to dB, of course. To do otherwise
would improperly penalize a lobed pattern (the dipole) that might
have one or two minus infinity dB gain values.)"

I know where I want to QSO to so I turn my 130' dipole broadside to AZ.

3. If you're still on board with all this, it would also be interesting
to know what happens to the elevation angle and gain of the
monopole if the number of radials is kicked up to a large number,
like 64.

It no doubt, goes up. 8 is all I ever installed. Seems to me a waste of
effort to use 32 times the copper that it takes for a dipole and still
not have the gain of a dipole. Incidentally, my 20m-10m dipole is
rotatable.

Well, I wasn't suggesting that you put more real copper in the ground;
I was just hoping you might put some more virtual copper in the model,
to see what happens.

As to quantity of copper (real or virtual), some folks find that wire is
cheaper than tall support masts. Other folks, perhaps with tall trees,
would see different trade-offs.

It's good your 20m-10m dipole is rotatable. Mine isn't. 8-(
But we were discussing the 130 footer, used on 30m.
If you can rotate that one, I'm impressed.

73, Ed

--
73, Cecil http://www.qsl.net/w5dxp