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Author Topic: Home-made backyard discone antenna for HF  (Read 3389 times)
K1CJS
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« Reply #15 on: September 04, 2009, 05:22:39 AM »

If you want to get some idea of what you're trying to accomplish, you can visit this site:

http://gvarc.us/GVARCFrames/Titan/Discone/Discone.htm

It's the 'Use our antenna' page of the Titan missile museum Web site in Arizona.  The antenna itself was built by the Collins company, and although there is little information about it there, you can get an idea of the size and the amount of wire and other things needed to put up such an antenna.

One thing to be noted is that the elevation there is approximately 2,900 feet above sea level.  That is probably one of the reasons it does pretty well there.
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W5DXP
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« Reply #16 on: September 04, 2009, 05:37:39 AM »

> N3OX wrote: So if you're an experimenter who likes experimenting for the sake of experimenting, by all means, ignore everyone who questions your motives in an internet forum, do the experiment, and come to your own conclusion. <

Yes, and if one wants to save an untold amount of wasted time, modeling the antenna before building it might be the way to go. EZNEC has allowed me to model hundreds of possible antenna designs of which only a handful were good ideas.
--
73, Cecil, w5dxp.com
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N8DV
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« Reply #17 on: September 04, 2009, 06:18:01 AM »

Thank you for all the responses. I did find a link to a Pfieffer Vertical cage antenna but no directions on how to build it. The web site hasn't been updated since 2004 so I don't know if the owner is still around.
In conclusion, I really couldn't build the discone antenna because of the small size of my lot. I just wanted to see what was out there. 73
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N5LRZ
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« Reply #18 on: September 04, 2009, 11:40:05 AM »

Re OX...

I put this "lack of gain" thing to be just a simple matter of being practical.  A dipole is just two wires streached out.  A discone is large number of wires constructied in a somewhat complicated manner.  And I guess that one would hope after going thru all that effort you will get an antenna with more gain than the just two wires streached out dipole.

However you are completely correct in that and if the reference books are also correct that the discone antenna has a very broad frequency range  something that the as you mentioned humble dipole does not have..

And (hi hi) you are beginning to sound like me (just a little bit):

"I think that it's not absurd to tell people you don't understand what advantages some particular antenna design has even if you've never built one."

It is frustrating is it not when you say something you know to be a fact but the world would much rather believe its delusions.
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N4OGW
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« Reply #19 on: September 05, 2009, 09:30:35 AM »

W5AOX: "As others have mentioned, there was an HF discone project in the ARRL Antenna Manual for several issues. We built one at Los Alamos for use as a broadband tracking antenna for sounding the ionosphere for current Maximum Usable Frequency. It actually worked quite well. Those who decry its "lack of gain" might consider it's got about the same gain as a dipole,"

Interesting...I actually used that LANL discone for the 1996 CW Sweepstakes. From what I remember, it wasn't big enough to go down to 3.5 MHz CW, so I also put up a dipole for 80/40. My impression was the discone worked about as well as a typical 1/4-wave vertical. The only real advantage is the broadband nature. For the lower ham bands a plain vertical is much easier to build and works just as well. For the upper HF a beam is much better.

Tor
N4OGW
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N0EQ
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« Reply #20 on: September 05, 2009, 03:51:51 PM »

N3OX wrote:
" ...I don't know about anyone else, but I don't have much need for an efficient transmit antenna that accepts power over the whole 1.8-30MHz spectrum..."

That certainly sounds like something I'd like to have in an antenna. Not sure why you wouldn't want it.

The discone efficiency curve is not ruler flat across the entire spectrum. The Green Valley discone in Arizona has a very nice SWR, reactance and resonance  at all the appropriate places.

The radiation pattern of a discone hugs the horizon quite a bit better than a dipole. With that comes it's obvious benefits.

I'm a big fan of that big birdcage in southern AZ.


Craig 'Lumpy' Lemke

www.n0eq.com
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N3OX
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« Reply #21 on: September 05, 2009, 07:13:05 PM »

"That certainly sounds like something I'd like to have in an antenna. Not sure why you wouldn't want it. "

Well I don't find myself needing a transmit antenna on

2-3.5 MHz
4-5.2 MHz
5.5-7 MHz
7.3-10.1 MHz
10.15 - 14.0 MHz
14.35 - 18.0 MHz
18.2 - 21MHz
21.5 - 24.9MHz
25-28MHz

That's an awful lot of spectrum that I don't need my antennas to work even a little on, and that's all I mean.  

Now, if you're going to put up ONE antenna ... OK, 9 bands plus the 60m channels?  That's a lot of antennas or a lot of multiple tuning.  I can see that.  Same for a Log Periodic to cover 20,17,15,12,10 ... got some simplicity compared to some 5 banders.

But for a few bands, I'll take a much simpler to build antenna myself.  that's all I was saying.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W2RKJ
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Posts: 55




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« Reply #22 on: September 28, 2009, 07:41:23 PM »

I was a volunteer on the USS New Jersey a few years back and the ship had a large discone located close to the bow. I used it to call CQ and was inundated with the responses. Man is it nice to be on the other end of a pile up. I loved that discone...
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WB6BYU
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« Reply #23 on: September 29, 2009, 10:50:49 AM »

I'm sure the salt water ground plane made far more
difference than the antenna itself.
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AA4PB
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Posts: 12988




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« Reply #24 on: September 29, 2009, 05:51:07 PM »

Being aboard the USS New Jersey probably didn't hurt any either :-) I was on the air from the USS Lake Champlain during the Gemni 5 recovery and had some monster pileups running a vertical through a tuner.
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