30 Meter antennas
KC1DI
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
Reg Edwards
rotateable, there's only a vertical to try. But I'm sure a vertical will
make a big difference - either for better or worse.
---
Reg.
Dan/W4NTI
"KC1DI" <kc...@arrl.net> wrote in message
news:jt46509rvejoqtg6n...@4ax.com...
I have used a variety of antennas on 30. At present I am using my 40m,
vertical loop, fed with 450 ohm line.
I also have a ladder line fed center fed, total length of 140' that I use
on AF MARS. Also does a good job.
Dan/W4NTI
WM2F
great results and when the band is open get good DX results. I also
have a homebrew vertical GP that has limited results. When switching
between the 2 antenna's the dipole always receives better.
I think the height of the dipole and whether it is cut for
resonances is a big factor. I dont use a tuner for 40 or 30 meters.
Also I have a 1:1 Van Gordon High Q Balun at the feed point. My coax
run is about 60 feet.
This is a tough time to evaulate antenna's. Band condx's are so poor
that we tend to blame our equipment. A few nights ago from New
Jersey, I was getting solid contacts to Europe and South America then
the band closed.
Best 73's
Mike
WM2F
Larry Gauthier (K8UT)
I have a full-wave horizontal loop on 30m and a multi-band vertical for 40 -
10 (1/4 wave on 30m). The vertical is 10 feet off the ground, the loop is at
40 feet. For "local" stuff (within several hundred miles) the loop is
better. For DX, the vertical beats the loop every time.
Try a 1/4 wave ground plane and see how it works.
-larry
K8UT
"KC1DI" <kc...@arrl.net> wrote in message
news:jt46509rvejoqtg6n...@4ax.com...
Jim Leder
the parts cost and it gives me both 40 and 30. It's a simple wire 1/4 wave
vertical for each band separated be PVC spreaders and it hangs from a tree
to a ground rod at the bottom. I have 8 16 foot radials around it (more in
the spring when the ground isn't frozen, probably up to 16). It has been
very effective on 30, better than the dipole I used prior to it. Performance
on 40 is OK. I am thinking of adding a 20 meter section. I have no problem
working DX with it on 30 or 40. Best thing I've tried on 30 so far.
"KC1DI" <kc...@arrl.net> wrote in message
news:jt46509rvejoqtg6n...@4ax.com...
Cecil Moore
> 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
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Cecil Moore
> 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)
--
73, Cecil http://www.qsl.net/w5dxp/SUPRGAIN.EZ
Old Ed
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" <Cecil....@ieee.ONEDOT.org> wrote in message
news:4054a4c8$1...@corp.newsgroups.com...
Cecil Moore
> 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
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Old Ed
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" <Cecil....@ieee.ONEDOT.org> wrote in message
news:4055147a$1...@corp.newsgroups.com...
Cecil Moore
> 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
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
John Passaneau
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
w3...@arrl.net
Old Ed
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
Mark Keith
> 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
Cecil Moore
> 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.
Cecil Moore
> Cecil Moore <Cecil....@ieee.ONEDOT.org> 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
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Mark Keith
> 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
Jim Leder
OK, it was a TIC, I know that, but how does it 'fool' EZNEC?
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:4057c...@corp.newsgroups.com...
Cecil Moore
> Cecil Moore <Cecil....@ieee.ONEDOT.org> 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).
Cecil Moore
> Cecil, OK, it was a TIC, I know that, but how does it 'fool' EZNEC?
It violates the element spacing rules. Very close spacing is not allowed.
I forget the details and stumbled upon it by accident. But that antenna
is really, really a "gain" antenna, radiating a lot more than it's
feedpoint power. :-) I should have waited until April 1.
Jim Leder
saved it.
I looked at your original on your web page and it would be interesting to
try on 30.
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:40586361$1...@corp.newsgroups.com...
KC1DI
stand by which seems to be working well..
it's an Off Center Fed Dipole 1 Wave Long and fed 1/4 wave from one
end. it's up as a sloper 50 feet on one end , 25 ft on the other..
Worke Iraq and Antartica on it the other night on 30m not bad..
Also have a 160m (520') Horizontal loop and the OFCD Or ( minimal
Long wire ) seems to be better by about 1 to 2S units on most station
except the Carabine which always seems better on the Loop. Also
Florida is better on the loop.
Have heard any Pacific openings since I put the ant up so will have to
reserve my opinon until that opens up.
73 to all hope to cu on 30 M
Dave kc1di
Old Ed
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:4057ca38$1...@corp.newsgroups.com...
> 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
Cecil Moore
> But we were discussing the 130 footer, used on 30m.
> If you can rotate that one, I'm impressed.
Actually, I can rotate that 130 ft dipole. I live on a
triangular shaped lot so I can rotate it about 60 degrees
from either end. Presently, I have it oriented so the cloverleaf
lobes point toward the world's land masses on the higher bands.
--
73, Cecil http://www.qsl.net/w5dxp
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Old Ed
Do you have alternate attachment points for one or both end(s)
of the antenna, and transfer said end(s) manually from one
attachment to the other?
If so, I would probably call the process "limited re-orientation"
or some such, vs. "rotation." But it's your antenna, so you get to
call it whatever you'd like.
And I guess there's no joy on modelling the average gain of
said antenna over azimuth. Oh well, it was a nice thought. 8-(
Good DX es 73, Ed
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:4058f...@corp.newsgroups.com...
Cecil Moore
> Do you have alternate attachment points for one or both end(s)
> of the antenna, and transfer said end(s) manually from one
> attachment to the other?
I have three poles arranged roughly in a triangle. My antenna has
quick disconnects on each end. It takes maybe three minutes to
rotate the antenna by 60 degrees.
> And I guess there's no joy on modelling the average gain of
> said antenna over azimuth. Oh well, it was a nice thought. 8-(
I offered to publish the azimuthal radiation pattern so you can
be the one to waste your time adding up 360 gains.
Richard Harrison
"Have you ever actually tried one of those? (20 dBI gain for 200 degrees
of the horizontal, a loop closely coupled for supergain)"
Excellent question.
J.D. Kraus is the leading exponent of the "supergain antenna"(W8JK)
which he warns has a price in low feedpoint impedance, low efficiency,
and reduced bandwidth (higher Q).
Felow author F.E. Terman reiterates Kraus` caveats.
Kraus says the W8JK has a gain of 5.8 dBi. That is pretty good for two
1/2-wave elements and compares with a 3-element Yagi. When you replace
the straifgt elements in a Yagi with loops to make a "quagi" you may
gain about 2 dB. Design it for maximum gain, and you may pick up about 2
more dB. So, with a "supergain quagi" why wouldn`t you expect gain to be
limited tio about 10 dB.
The W8JK pattern is a figure-8 almost like a dipole but it gets 5-6 dBi
gain from reorientation of energy and that is 3-4 dB better than a
dipole. An array of two close-spaced quads will probably be sharper yet.
The W8JK pattern is shown in Fig 71 on page 8-50 of the 19th edition of
the ARRL Antenna Book. It seems to have about 100-degrees of beamwidth
in forward and reverse directions, so that may qualify as 200-degrees.
Best regards, Richard Harrison, KB5WZI
Dan Richardson <
<Cecil....@ieee.ONEDOT.org> wrote:
>I offered to publish the azimuthal radiation pattern so you can
>be the one to waste your time adding up 360 gains.
Cecil,
If you wish you can send me the *.ez file and I'll run it with
MultiNec using the EZNEC engine. As MultiNec is an Excel worksheet it
is very easy to set up an unused cell to give the average gain of a
polar plot.
Or if you wish you can do it youself. MultiNec can be downloaded at:
http://www.qsl.net/ac6la/
73
Danny, K6MHE
Cecil Moore
> Cecil, W5DXP wrote:
> "Have you ever actually tried one of those? (20 dBI gain for 200 degrees
> of the horizontal, a loop closely coupled for supergain)"
>
> Excellent question.
Richard, my posting was a tongue-in-cheek joke.
That antenna has an efficiency far in excess of 100%.
--
73, Cecil, W5DXP
Richard Harrison
"Have you ever actually ttried one of those?" to Cecil Moore. Mark Keith
asked as a response to Cecil. Sorry for the mistake, but it is an
excellent question that belongs to Mark Keith.
Cecil Moore
> If you wish you can send me the *.ez file and I'll run it with
> MultiNec using the EZNEC engine.
Hi Danny,
I'm at work and the file is at home, but it is just a 130 ft.
dipole, 40 ft. high, used on 10.125 MHz over average ground.
The wire in EZNEC looks like: 0, 0, 40 130, 0, 40 #14 131
--
73, Cecil, W5DXP
Dan Richardson <
Based on the above, the average azimuth gain @ 34ē EL is 1.822 dBi
Danny
Cecil Moore
> <Cecil....@ieee.ONEDOT.org> wrote:
>>The wire in EZNEC looks like: 0, 0, 40 130, 0, 40 #14 131
>
> Based on the above, the average azimuth gain @ 34ē EL is 1.822 dBi
Thanks, that beats the average azimuthal gain for a
ground-mounted 1/4WL monopole.
--
73, Cecil, W5DXP
Old Ed
Thank you very much for your contribution here!
Any chance you could run another 360 azimuth cut
at 26 degrees elevation?
TNX es 73, Ed
"Dan Richardson @mendolink.com>" <<ChangeThisToCallSign> wrote in message
news:691k50tj9b9fl27ol...@4ax.com...
> Based on the above, the average azimuth gain @ 34ş EL is 1.822 dBi
>
> Danny
>
Old Ed
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:405a1abb$1...@127.0.0.1...
Using your numbers for the (somewhat radial-challenged) monopole,
the monopole peak is 1.822 dB less, but at a more favorable (for DX)
26 degrees elevation angle.
I would say that's not a bad showing, considering the much smaller
footprint and greatly reduced support requirements. But beauty is
in the eye of the beholder; and I wouldn't dream of trying to steal
your affections from the big dipole.
73, Ed
> --
> 73, Cecil, W5DXP
>
>
Cecil Moore
> I would say that's not a bad showing, considering the much smaller
> footprint and greatly reduced support requirements.
Huh???? My 40m monopole was the most difficult antenna I have
ever attempted to erect. My dipole goes between two trees and
gives me 9 dBi gain toward AZ on 30m. It's no contest.
Dan Richardson <
<eseniorsR...@earthlink.net> wrote:
>Hi Danny -
>
>Thank you very much for your contribution here!
>Any chance you could run another 360 azimuth cut
>at 26 degrees elevation?
>
>TNX es 73, Ed
Sure Ed, however as you are comparing the dipole to a monopole I also
modeled that. The monopole was resonated at 10.125 MHz. Using 16
¼-wave in length buried 5" deep. The maximum elevation takeoff angle
reported by EZNEC/pro using the NEC4 engine was 27º.
Here are the results for average gain at 27º EL.
Monopole -1.11 dBi
Cecil's dipole 1.596 dBi
73
Danny
Old Ed
I appreciate your inputs, and I really don't want to pull your chain.
But I gotta say you are quite the maestro of the biased comparison!
[ Have you considered working for a network news show? ;-) ]
1. The discussion was about a 30m monopole, I thought.
2. If trees are assumed to be available to support dipoles,
then trees could be used to support a monopole.
But not being clairvoyant, I didn't know about your trees.
So what I had in mind was a self-supporting monopole,
versus 2 or 3 self-supporting dipole masts.
3. As to the gain figure, you seem to assume that the
dipole is always operating at the peak of one of its
lobes, and never has to operate in one of its nulls.
If only specific directions are of interest to you,
and if the dipole is oriented for those directions,
and if the operating frequency is low enough to
avoid multi-multi-lobe fragmentation of the pattern,
then I guess that's a good assumption for your situation.
But one can't assume that this assumption would apply
to everyone.
Here's some good news, though... Just to show you I believe
in being fair all around, I am honor-bound to report that:
Danny came up with a lower gain than you did for the modeled
monopole, thus increasing the modeled dipole's average
advantage to 2.7 dB.
BTW, I'm also using and enjoying dipoles out here in the
land of fruits and nuts.
73! Ed
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:405a4...@corp.newsgroups.com...
Cecil Moore
> Here are the results for average gain at 27º EL.
>
> Monopole -1.11 dBi
> Cecil's dipole 1.596 dBi
For more of an omni-directional pattern, a 24 ft wire hanging
down from both ends of the dipole will beat the monopole by at
least a dB in *all* directions and by 6dB in four directions.
Cecil Moore
> 2. If trees are assumed to be available to support dipoles,
> then trees could be used to support a monopole.
But trees absorb energy from the monopole which has no gain
to waste. Trees absorb virtually no energy from a dipole.
> 3. As to the gain figure, you seem to assume that the
> dipole is always operating at the peak of one of its
> lobes, and never has to operate in one of its nulls.
I never operate my antenna in a null. I also don't drive my
pickup one mile per hour even if I only average driving it
one hour per day. Seems by your logic, I should always walk
since I can walk faster than the average speed of my pickup
over any 24 hour period. :-)
--
73, Cecil http://www.qsl.net/w5dxp
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Richard Clark
<eseniorsR...@earthlink.net> wrote:
>Oh, Cecil, Cecil, Cecil!
>If trees
>you seem to assume
>If only
>and if
>and if
>then I guess
Good guess, but about what?
73's
Richard Clark, KB7QHC
Cecil Moore
> On Fri, 19 Mar 2004 04:11:32 GMT, "Old Ed"
> <eseniorsR...@earthlink.net> wrote:
>
>>Oh, Cecil, Cecil, Cecil!
>>If trees
>>you seem to assume
>>If only
>>and if
>>and if
>>then I guess
>
> Good guess, but about what?
Please look up "analogy" in the dictionary and "conditional
statements" in a good logic book. And look up "emoticon"
on the web.
--
73, Cecil http://www.qsl.net/w5dxp
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Old Ed
I no longer aspire to cornering you into an unbiased comparison.
I can see you're much too crafty for that! ;-)
But I don't want you to think I'm easily fooled, either.
So a couple more comments below...
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote
in message news:405a7...@corp.newsgroups.com...
> Old Ed wrote:
> > 2. If trees are assumed to be available to support dipoles,
> > then trees could be used to support a monopole.
>
> But trees absorb energy from the monopole which has no gain
> to waste. Trees absorb virtually no energy from a dipole.
>
OK, we need to assume that you have a couple of trees that
are 130+ feet apart, because you say you are using them to
support a dipole of that length.
So instead of a "T" between the trees where the top is a
dipole and the vertical element is the feedline, why not
a "T" between the trees where the top is a support rope
and the vertical element is a monopole? Do you think
a couple of trees 65+ feet away from said monopole
would suck up all its radiated energy? And if so, why
wouldn't they clobber the much closer, high-impedance
ends of the dipole?
BTW, I repeat that I'm NOT trying to convert you to a
different antenna type; I'm merely advocating some
technical objectivity when making comparisons.
> > 3. As to the gain figure, you seem to assume that the
> > dipole is always operating at the peak of one of its
> > lobes, and never has to operate in one of its nulls.
>
> I never operate my antenna in a null.
This is quite a remarkable feat! Do you only talk to a list
of favored stations that are known to lie in your lobes?
Or do you refuse to answer a list of stations that lie in your
nulls? (Or if they're DEEP in a null, you might be unaware
of their existence, I suppose.)
> I also don't drive my
> pickup one mile per hour even if I only average driving it
> one hour per day. Seems by your logic, I should always walk
> since I can walk faster than the average speed of my pickup
> over any 24 hour period. :-)
I'm afraid this analogy is so strained and inapplicable that
it doesn't really need a response.
Richard Harrison
"---trees could be used to support a monopole."
Yes, but in supporting a monopole, the tree is more or less parallel,
near, and lossy. Horizontal dipoles are somewhat perpendicular to trees
which are likely to be in the nulls of the dipole pattern.
Shortwaves are propagated effectively by bounce at the correct angle off
the ionosphere. Propagation of shortwaves along the earth`s surface is
seriously attenuated.
Vertical antennas up to 5/8-wavelength launch their maximum signal along
the earth`s surface, not good for skywave propagation in most cases. It
works at sea where conductivity is excellent and over much greater
distance than over land, so that not all shortwave tangential energy is
necessarily wasted.
Horizontal antennas produce no tangential aignal along highly conducting
earth. The reflection at near zero elevation is equal and opposite in
polarity and it cancels.
High 1/2-wave dipoles (between 1/4-wave and 1/2-wave high) have gains at
some angle between zero and 90-degrees as compared with the same dipole
in free-space.
A 1/2-wave dipole between 1/4-wave and 1/2-wave above good ground can
have a dB or two gain at some elevation angle between 15 and 30-degrees.
It`s not much, but it`s not a loss. Even over poor ground, the
free-space 1/2-wave dipole characteristic is likely available at the
useful elevation angle.
I worked for years in shortwave broadcasting and have yet to see any
facility which employed vertical transmitting antennas. I`ve heard there
are some verticals, but when serious investment is professionally made
in shortwave transmitting antennas it is nearly always made in the
horizontally polarized variety.
Tdonaly
Richard Harrison wrote,
>
>I worked for years in shortwave broadcasting and have yet to see any
>facility which employed vertical transmitting antennas. I`ve heard there
>are some verticals, but when serious investment is professionally made
>in shortwave transmitting antennas it is nearly always made in the
>horizontally polarized variety.
>
>Best regards, Richard Harrison, KB5WZI
>
Medium and Long Wave, on the other hand...
73,
Tom Donaly, KA6RUH
Cecil Moore
> So instead of a "T" between the trees where the top is a
> dipole and the vertical element is the feedline, why not
> a "T" between the trees where the top is a support rope
> and the vertical element is a monopole?
Given that, I've gone to all the trouble of putting up a
dipole. Why would I choose to put up something inferior
to a dipole? Plus, with a vertical, I would have to lay
in a ground plane only to make my noise level 2 S-units
worse than with the dipole. Where's the ROI?
> Do you think
> a couple of trees 65+ feet away from said monopole
> would suck up all its radiated energy? And if so, why
> wouldn't they clobber the much closer, high-impedance
> ends of the dipole?
Because the trees then act as part of the end-hat circuit
which is a good thing.
>>I never operate my antenna in a null.
>
> This is quite a remarkable feat! Do you only talk to a list
> of favored stations that are known to lie in your lobes?
Yes, that's why I placed the lobes where they are.
> Or do you refuse to answer a list of stations that lie in your
> nulls?
I don't QSO with weak signals. Life is too short for QRP.
>>I also don't drive my
>>pickup one mile per hour even if I only average driving it
>>one hour per day. Seems by your logic, I should always walk
>>since I can walk faster than the average speed of my pickup
>>over any 24 hour period. :-)
>
> I'm afraid this analogy is so strained and inapplicable that
> it doesn't really need a response.
It's the same logic. You are arguing that the average radiation
pattern is what is important and not the directional gain while
it is performing useful work.
So to be consistent, you must also argue, that it is the average
speed of my pickup that is important and not the speed while it
is performing useful work.
Since the average gain of a beam is about equal to a vertical,
do you advocate getting rid of all the beams? :-)
--
73, Cecil, W5DXP
Richard Clark
(Richard Harrison) wrote:
>Old Ed wrote:
>"---trees could be used to support a monopole."
>
>Yes, but in supporting a monopole, the tree is more or less parallel,
>near, and lossy. Horizontal dipoles are somewhat perpendicular to trees
>which are likely to be in the nulls of the dipole pattern.
Hi Richard,
It is equally arguable that trees. being at the distal, high potential
ends of a source, present inconvenient shorting paths to ground. They
are much larger than any expected dipole support by being very wide,
and randomly forked - dare I say a fractal load?
Old Ed
THANKS!
73, Ed
"Dan Richardson @mendolink.com>" <<ChangeThisToCallSign> wrote in message
news:romk50t276aahu6s0...@4ax.com...
Old Ed
Comments below...
"Richard Harrison" <richard...@webtv.net> wrote in message
news:22243-405...@storefull-3253.bay.webtv.net...
> Old Ed wrote:
> "---trees could be used to support a monopole."
>
> Yes, but in supporting a monopole, the tree is more or less parallel,
> near, and lossy. Horizontal dipoles are somewhat perpendicular to trees
> which are likely to be in the nulls of the dipole pattern.
>
The false assumption here is the qualifier "near." If you were worried
about tree proximity, you could place the trees arbitrarily far from the
monopole, by using the "T" support I described in my response to Cecil.
As to the nice summary of ARRL handbook data that you provide in the
following paragraphs, I am aware of it, and I do not take issue with it.
My point in responding to Cecil was to introduce some OBJECTIVITY
into the vertical/horizontal comparisons. I was NOT trying to convince
anyone they should switch antennas, or that verticals solved all problems.
73, Ed
Old Ed
then I'll go into bandwidth conservation mode....
"Cecil Moore" <Cecil....@ieee.ONEDOT.org> wrote in message
news:405b3...@127.0.0.1...
> Old Ed wrote:
> > So instead of a "T" between the trees where the top is a
> > dipole and the vertical element is the feedline, why not
> > a "T" between the trees where the top is a support rope
> > and the vertical element is a monopole?
>
> Given that, I've gone to all the trouble of putting up a
> dipole. Why would I choose to put up something inferior
> to a dipole? Plus, with a vertical, I would have to lay
> in a ground plane only to make my noise level 2 S-units
> worse than with the dipole. Where's the ROI?
>
I will interpret your subject change here as conceding
the point I was trying to make.
> > Do you think
> > a couple of trees 65+ feet away from said monopole
> > would suck up all its radiated energy? And if so, why
> > wouldn't they clobber the much closer, high-impedance
> > ends of the dipole?
>
> Because the trees then act as part of the end-hat circuit
> which is a good thing.
>
This is somewhere between incoherent and grasping at
straws, so again, I will consider the point made.
> >>I never operate my antenna in a null.
> >
> > This is quite a remarkable feat! Do you only talk to a list
> > of favored stations that are known to lie in your lobes?
>
> Yes, that's why I placed the lobes where they are.
>
> > Or do you refuse to answer a list of stations that lie in your
> > nulls?
>
> I don't QSO with weak signals. Life is too short for QRP.
>
Great, this is progress... we now know your ground rules!
But I assume you will acknowledge that there are quite a
few other amateur stations that want to be unrestricted in
azimuth.
> >>I also don't drive my
> >>pickup one mile per hour even if I only average driving it
> >>one hour per day. Seems by your logic, I should always walk
> >>since I can walk faster than the average speed of my pickup
> >>over any 24 hour period. :-)
> >
> > I'm afraid this analogy is so strained and inapplicable that
> > it doesn't really need a response.
>
> It's the same logic. You are arguing that the average radiation
> pattern is what is important and not the directional gain while
> it is performing useful work.
>
> So to be consistent, you must also argue, that it is the average
> speed of my pickup that is important and not the speed while it
> is performing useful work.
>
Sorry, this didn't get any better. It's still nonsense, as an analogy.
> Since the average gain of a beam is about equal to a vertical,
> do you advocate getting rid of all the beams? :-)
No, not all of them... only the ones that need to cover 360 degrees
azimuth, and don't rotate. 8-)
73 es QRT, Ed
> --
> 73, Cecil, W5DXP
>
Cecil Moore
> I will interpret your subject change here as conceding
> the point I was trying to make.
I thought Danny's calculations had already conceded
your point.
>>Because the trees then act as part of the end-hat circuit
>>which is a good thing
>
> This is somewhere between incoherent and grasping at
> straws, so again, I will consider the point made.
Trees are part of the world that provides capacitance
for the ends of dipoles.
> Great, this is progress...
No, this is humor.
> But I assume you will acknowledge that there are quite a
> few other amateur stations that want to be unrestricted in
> azimuth.
Of course, that's why I suggested the two 24 foot wires hanging
down from the ends of the 130 ft. dipole as a way to cause the
dipole to beat the vertical in any and all directions and by
as much as 6 dB in four directions.
--
73, Cecil, W5DXP
KC1DI
Have been using the OCF 1 wave Dipole for about 1 week now , worked
3B9C on 30m Lots of Qrm. Worked antartica , Iraq so far country
totals are at about 30 worked . Continents of SA EU Asia and Africa
have been worked haven't heard any Down under stations or fareast Asia
Pacific rim yet.. But so far been very please with the antenna ,
it's 92.5 feet overall fend 1/4 wave for the top end with 75 ohm coax.
high end is at 50 feet low end at about 22 feet slopes fro west to
east. Pattern looks good on modeling software highest gain is at
about 35 degrees. seems to be working well for me.
73 , Dave