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Old March 15th 04, 05:02 AM
Old Ed
 
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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





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Old March 15th 04, 05:50 AM
Cecil Moore
 
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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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Old March 15th 04, 03:17 PM
John Passaneau
 
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"KC1DI" wrote in message
...
Just curious as to what most of you are using as an antenna on
the 30 Meter band?

I've used many and was just wondering if i could improve my overall DX
performance with something other than a Dipole. With out going to the
expense of a Beam.

73 Dave


Look at a half square, could give you more than 3dbi of gain at a very low
angle, with no ground radials required.


--
John Passaneau, W3JXP
Penn State University



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Old March 17th 04, 02:20 AM
Old Ed
 
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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



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Old March 17th 04, 04:11 AM
Mark Keith
 
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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?


Actually, my all time favorite antenna is a 40m loop closely coupled
for supergain. It has 20 dBi gain for 200 degrees of the horizontal.
It would make my 100 watt transceiver sound like about 10 kilowatts
and could be scaled for 30m but watch out for complaints that you are
running illegal power. The EZNEC file can be downloaded from my web
page below. (TIC disclaimer)


Have you ever actually tried one of those? I ran it thru expecting to
see a real low Z input, but was fairly high for a "supergain" type
scheme. I had to reduce the segment number to run in the demo...I got
26.3 dbi...??? I'm sort of skeptical that those actually live up to
the specs. Seems everyone would be using one...
20+ dbi is a pretty happy amount of gain for a simple loop like that.
Heck, a rhombic would have to be pretty big to do that well. Or takes
many elements for a yagi...Color me pretty skeptical til I see one in
action....:/ MK


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Old March 17th 04, 04:46 AM
Cecil Moore
 
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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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Old March 17th 04, 04:50 AM
Cecil Moore
 
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Mark Keith wrote:

Cecil Moore wrote:
Actually, my all time favorite antenna is a 40m loop closely coupled
for supergain. It has 20 dBi gain for 200 degrees of the horizontal.
It would make my 100 watt transceiver sound like about 10 kilowatts
and could be scaled for 30m but watch out for complaints that you are
running illegal power. The EZNEC file can be downloaded from my web
page below. (TIC disclaimer)


Have you ever actually tried one of those?


Uhhhh Mark, "TIC" stands for Tongue-In-Cheek. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Old March 17th 04, 10:46 AM
Mark Keith
 
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Cecil Moore wrote in message ...
Mark Keith wrote:



Uhhhh Mark, "TIC" stands for Tongue-In-Cheek. :-)


If it ain't in plain langauge, I probably won't understand it...
I don't keep up with many of those...To me, a "tic" is kind of a
jerking motion usually in the facial area...:/ I knew that antenna had
to be a April fool's special of some kind... MK
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Old March 17th 04, 02:57 PM
Jim Leder
 
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Cecil,

OK, it was a TIC, I know that, but how does it 'fool' EZNEC?


"Cecil Moore" wrote in message
...
Mark Keith wrote:

Cecil Moore wrote:
Actually, my all time favorite antenna is a 40m loop closely coupled
for supergain. It has 20 dBi gain for 200 degrees of the horizontal.
It would make my 100 watt transceiver sound like about 10 kilowatts
and could be scaled for 30m but watch out for complaints that you are
running illegal power. The EZNEC file can be downloaded from my web
page below. (TIC disclaimer)


Have you ever actually tried one of those?


Uhhhh Mark, "TIC" stands for Tongue-In-Cheek. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Old March 17th 04, 03:34 PM
Cecil Moore
 
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Mark Keith wrote:
Cecil Moore wrote:
Uhhhh Mark, "TIC" stands for Tongue-In-Cheek. :-)


If it ain't in plain langauge, I probably won't understand it...
I don't keep up with many of those...To me, a "tic" is kind of a
jerking motion usually in the facial area...:/ I knew that antenna had
to be a April fool's special of some kind... MK


A "TIC" is a "TLA" and is kind of a jerking motion usually in
the area of the leg (or funny bone).
--
73, Cecil http://www.qsl.net/w5dxp



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