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w8eeo

Posts: 2,219 Member Since: 10/04/08

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Jan 4 10 9:37 PM

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Two Loops 80-10 Meters
 One of the most unique home brew HF antennas is the Skelton Cone. This antenna will operate on 10M - 80M and is reported to show gain above 40 meters. The antenna is almost never used now.
There is a lot of literature on the Cone. It first appeared in in the RSGB Handbook ( 3rd edition, pp 387), and again in 73 Magazine ( Aug. 1969, pp 133 ) and was deeply researched by the late K6LV, in many different configurations.
The antenna looks very much like two G5RV antennas on one feed line. Basically it is. It's just a G5RV that has been broad banded by adding additional legs and spreading them apart.
The feed point can be set 38-48 feet high, with the legs sloping down to about 18 feet at the ends. The 33 degree angle between the leg pairs works out to be about 28 feet. Also, the feed point separation should be set at 4 inches wide. These configurations are not absolute. The Cone is very forgiving in different configurations of installation.
Feed the cone with 38 feet of 300 to 600 ohm twin lead connected to the balanced output of a good tuner. Note. Add 33 foot increments of feed line if more is needed above the basic 38 feet.
Performance reports are unique. Computer models show the highest gain of the cone towards the 10M end of the scale, but the antenna really shines on 40 and 80 meters. In addition, the antenna exhibits the best points of both horizontal and vertical omnidirectional antennas, with none of the apparent drawbacks.
NOTES:
As you probably know a G5RV was not designed to be an "ALL-BAND" antenna. G5RV
designed it to be an antenna with gain on 20 meters. The fact that it works on the
other bands is incidental. Also, the G5RV was not intended to be installed in a
configuration other than a flat top. With a big enough tuner, it can be made to show
a low SWR in any configuration, but this more a function of the tuner's ability to
force current into the feed line rather than the antenna's resonance at any certain
frequency. Still, the major problem will be with the radiation patterns this antenna
displays when it is installed as an inverted vee.
At 1 1/2 wave lengths on 20 meters, it does have gain, but when the ends are
lowered down into a vee configuration the lobes change shape and the angle of
radiation changes in the direction of lost efficiency. On the bands above 20 meters
the lobes of radiation are shaped more like those of a long wire than a dipole, and
when this antenna is erected as an inverted vee, the pattern worsens and the gain diminishes.
To be continued...



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w8eeo

Posts: 2,219 Member Since:10/04/08

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Jan 5 10 2:20 PM

So Now I have the antenna put up and ready to test it for swr and also hopefully some on air tests.
The tuner which I used is the Palstar AT1500 BAL which is a balanced tuner.
The other tuner which I will use for testing is the TenTec 238B which will tune mis-matches which the Palstar won't. The TenTec Will tune just about anything on 80-10 meters. However it is a bit flaky on 160 meters. TenTec could have spent a few more dollars and beefed up and increased the amount of capacity for use on 160- but that is another story.
The balanced tuner brought the swr flat on all the bands including the WARC bands. That is great but in the last several decades I have learned that a dummy load will also show your transmitter a flat load. So a low srw is not always the best test of how an antenna is going to perform anywhere.
There was one set of facts that I was aware of when I made the antenna. That is the fact that a dipole antenna always reaches the point where the lobes change to that of a long wire as we increase frequency. An inverted Vee is limited by that fact to a group of frequencies in the lower bands for the best gain, directivity etc. Referring to the Cone:
"At 1 1/2 wave lengths on 20 meters, it does have gain, but when the ends are
dropped down into a vee configuration the lobes change shape and the angle of
radiation changes in the direction of lost efficiency. On the bands above 20 meters
the lobes of radiation are shaped more like those of a long wire than a dipole, and
when this antenna is erected as an inverted vee, the pattern worsens and the gain diminishes."
At the risk of repeating myself if you don't get anything else about this project, it is the fact that a low srw is only part of the story.
The Skelton Cone in it's present configuration (inverted Vee) will perform well on 80M, 60M, 40M and 30M. However on 20M and higher it will not be a performance antenna in spite of the fact that the swr was flat on the higher bands.
The following are the steps I took to make a pretty good antenna for all the bands 80-10 meters.
more to follow...

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w8eeo

Posts: 2,219 Member Since:10/04/08

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Jan 6 10 10:30 PM

Latest Changes and results:
I ran the cone for 2 years starting in the Spring of 2002 till the Spring of 2004 without any changes. I had the center at about 44 feet on the tower and the end insulators were hanging about 18-20 foot from the ground.
The antenna was a joy to operate and I was able to learn a lot about it.
If there is any gain involved with it it would be off the ends which point northeast and southwest.
The only fone contacts I make are on 75 meters each morning beginning at about 8:00 AM when I meet with the gang I have met with for years. On 75 there was not a lot of difference with the antenna when it was compared to my doublet that I had been using. It did not seem to be as good as my doublet on long haul 80 meter work.
On 40 meters CW the antenna was a pleasant experience. I had remembered from the old literature that there was some gain on the cone compared to a half wave dipole on 40. The cone is the best 40 meter antenna I have used in all my years on 40 CW.
On 60 meters the antenna worked great and I made many contacts although I don't like fone that well. I got very good reports and many questions about the antenna.
30 meters worked very well.                                                                                                   I made contacts on all the bands thru 10 meters during the 2 years and considering the terrible propagation effects the contacts were good.
One thing I have noticed about the cone and especially since I added 2 jumpers on the ends of the legs (see below) is the fact that it was a very noise free antenna in my location.
More to follow...



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w8eeo

Posts: 2,219 Member Since:10/04/08

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Jan 6 10 11:05 PM

During the winter of 2003-2004 I googled everything I could find on the Skelton cone which was not very much. I found one site which had quite a bit of information but nothing new at http://home.pacbell.net/serazin/cone.html - The writer had used the antenna as described in early literature and although he thought it was a pretty good antenna he was quite critical about the loss caused by wrong wave angles on the higher frequencies. I have no doubt that the faults are there but as I mentioned earlier in my opinion it was about as good as a so called "all band" antenna could be.
Also, I discovered that there was a small company in Florida who was making the Skelton cone for some commercial and Military customers. I requested information from him which I received in a few days. His finished product was just like my set-up except he had a upgrade for the antenna which consisted of a jumper across each end which made the antenna 2 loops of sorts. The reason it seems is to lower the resonant frequency on 80 meters as well as to iron out some transmit signal direction problems on 20 meters and above. There was still snow on the ground but I was ready to add the jumpers. By the way the price he wanted for the antenna was a bit much. A ham could make 2 or 3 for the price he wanted. It seemed that the only thing I needed to do was fill in the opening on each end and make 4 solder connections.
A,C,D,F 51.0'  B,E 30.0' total wire per side 132'
Feedline should be computed with 38' as the basic feed length. If you need more additional feed line the length should be in 33' increments. If you end up with extra feedline after adding a 33' increment don't cut it off. Merely make a zig-zag or something. It is not a good idea to coil the 450 ohm feeders.
For example the length would be one of the following: 38', 71', 104', 137 ' etc.
It is not a good idea to put a balun in the feedline and try to run coax to the rig. I run my 450 ohm line to the back of the tuner. Both the Palstar and 238B shown above will tune on every band 80-10 meters.
The antenna will work well with the center at 38'-48' and the ends at 18' or so. However some of the old timers say that the higher the better and also get as near as you can to a flat top. I have been using mine with the center at 55' and ends at 45' or so and I love the way it works. The 30' jumper tied into each end brought my 80 meter resonant point to around 3540 KHZ or so. However it is a complex antenna and I have never seen a computer model writeup. I have no computer model or other fancy information to show.If you do one send me a copy hi.
I hope you have been able to follow my chain of thought. By the way if you wanted to it would be possible to get a very compact antenna with 40 meters being the bottom band. Just use 1/2 of all the measurements shown above for the 80 meter setup (See below for suggested measurements). 73 gl w8eeo
(ps) The crude drawing may be a bit confusing. Just imagine looking at the antenna from a birds eye view. In other words the end jumpers will be level as opposed to the jumper being vertical.



Last Edited By: w8eeo Jan 7 16 9:11 PM. Edited 3 times.

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w8eeo

Posts: 2,219 Member Since:10/04/08

#4 [url]

Jan 10 10 11:48 PM

For 40 meters the following lengths might work: A.C,D.F = 25.5' B, E = 15.0'. basic feedline = 19.0' with added increments 16.5' or 19.0', 35.5, 52.0, 68.5, 85.0 etc.
These measurements are not the results of a tried antenna but rather by the formula.
A basic antenna on 40 meters would not suffer with wave takeoff angles problems on 20 meters or the upper WARC bands. However, 10 meters might be a bit flaky if the antenna is not a flat top product. Also it would be a compact antenna for all the bands 40-10 meters. If you build the antenna it may be necessary to prune or add a bit here and there.

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sispy

Posts: 1,579 Member Since:11/05/08

#5 [url]

Jan 22 10 2:30 PM

Check me out on this! For 160 meters I compute: A,C,D,F=102'. B,E=60' which comes out to about 264' of wire in each loop. For feeders either 76', 142', 208' 274' etc. (all this is a serious amount of wire). Also the feeders could have a lot of extra wire to position depending on how far it is to the antenna center.
Still, in a plot of land 204'X60' it looks like a good project. They say with the an antenna cut to 80 meters as the bottom band there is upwards of 5.5 to 7 db gain over a dipole on 40 meters. If the same plan works with this antenna at 160 meters for the low band this thing would be great on 80 meters.

For the latest information about Ham Radio, Communications, Radio News, Space, Radio History...Join me in the discussion at hamchatforum.lefora.com

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wn4j

Posts: 3 Member Since:10/09/08

#6 [url]

Feb 4 10 1:16 PM

 My name is Bob, WN4J.  A few years ago while Zeke W8EEO and I were round-table friends on 80- Meter SSB,  I built a 160-Meter Skelton cone from electric fence wire (1/2 mile spool from the local hardware for around $10.00) with very interesting results. Briefly, it seemed to equal the performance of my full-wave 80-Meter loop on 80 and 40.  It seemed to perform less than my full sized 160-Meter square loop at 60 feet height.  But on 17-Meters,  surprisingly, it was dynamite!  I tuned up with a "testing" transmission on 17-Meter USB on a dead band and European stations came back to me! The band was dead and I was QSO'ing Europe with good signal reports. That's why I love antenna experiments ... you can get some real surprises sometimes. 

Bob WN4J

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hash

Posts: 15 Member Since:02/09/10

#7 [url]

Feb 11 10 1:06 PM

Desirable Phaser specifications

phase control

§         must cover the full 360°

§         linear scale for maximum phase control spreading **

§         knowledge of the actual phase setting

§         logical scale for application in an array (linear from -90° via 0° to +90°)

§         reproducible and stable control

gain control

§         implemented as a balance (ratio) control

§         accurate by using a gain control spreading **

dynamic range

§         good large signal behaviour

§         negligible noise contribution

broadband

§         phase and gain both frequency independent

(gain and phase control must be also independent)

cost

§         easy to build and no expensive components

 
** phase and gain control spreading is essential for obtaining deep nulls. Just like bandspreading is for accurate frequency control

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w8eeo

Posts: 2,219 Member Since:10/04/08

#8 [url]

Feb 15 10 10:55 PM

There was a company in Florida who for several years sold the spydercone antenna to amateur buyers. Also, I understand that he made and sold to other Industrial and Military buyers. The name of the company was Genesis High Frequency. What will be shown here are some bits and pieces from different sites about the antenna and user comments. The Company is no longer in business. At the time he was in business there the site was http://www.coneantenna.com
http://www.eham.net/reviews/detail/2034
http://www.eham.net/forums/Elmers/42520
If you have additional information which is not in the thread yet please add it here> Thanks.

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w8eeo

Posts: 2,219 Member Since:10/04/08

#9 [url]

Mar 3 10 3:29 AM

The legacy of Louis Varney (I), by Louis Varney, G5RV

On June 28, 2000, at 89, Louis Varney, alias G5RV, rejoined the large family of silent keys hams. To pay tribute to this famous amateur radio, I would like to present you one of the main work he shared with the ham community : the invention of the G5RV dipole antenna...
http://www.astrosurf.com/luxorion/qsl-g5rv.htm

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w8eeo

Posts: 2,219 Member Since:10/04/08

#10 [url]

Mar 13 10 9:17 PM

Here is a handy tool that you can use to determine length of radiator to arrive at frequency it is resonant at. Or, if you enter the frequency which is your target it will give you the length of radiator. Other factors will apply such as diameter and composition but all in all this is an easy tool that will remove resorting to a formula in many cases.
http://www.qsl.net/kd4sai/antencal.html

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w8eeo

Posts: 2,219 Member Since:10/04/08

#12 [url]

Oct 11 10 1:32 AM

Near-Vertical Incident Skywave  (nvis)
After a period of testing where this Bow tie was compared to a half-wave dipole nearly a quarter wave high on 80 meters it was found that although the bow tie antenna had several desirable traits, it was not a good antenna for normal (all around) amateur work.
Soon I will have the test information together and I will post it here. The reason for this post is to ask anyone who is planning to erect the antenna to wait a few days for the results of my testing here. This is a true "cloud warmer" type antenna which is great for local work (300-400 miles) but is not very good for longer skip. If you work only local nets or round tables this is an interesting antenna.
The following is a run-down on other articles which can be found on hamchatforum:


Nov 13, 2009 ... NVIS, or Near Vertical Incidence Skywave propagation is a form of ionospheric radio propagation that can be used where radio communications ...
hamchatforum.lefora.com/2009/11/13/nvis-propagation/
Dec 28, 2008 ... [url] THE W4UJW ANTENNA PROJECTS DESIGN LAB ******* [url] Antenna Software compiled by AC6V ******* [url] NVIS Antennas and Propagation.
hamchatforum.lefora.com/2008/12/28/antenna-information-and-construction/
Apr 3, 2009 ... These PIXIEs are not really super-duper DX gear, so making a few local & regional NVIS QSOs with your club mates will be as much we can ...
hamchatforum.lefora.com/2009/04/03/ne-qrp-club-brews-a-fine-filter/
He is contemplating using it for NVIS on 80 meters. He desires to lower it to about 15 feet to improve the NVIS characteristics. ...
hamchatforum.lefora.com/2009/11/16/nvis-80m-with-160m-full-wave-loop-is-less-than-ide/
Nov 25, 2009 ... This tower has sixty 140- foot long buried radials for lightning protection and to help with low NVIS antennas like dipoles. ...
hamchatforum.lefora.com/2009/11/25/transmitting-antennas-at-w8ji/
f you are planning on Expedition for the Virginia QSO Party you are certainly planning for Near Vertical Incident Skywave (NVIS) communications on the lower ...
hamchatforum.lefora.com/2009/11/16/several-sources-for-telescoping-masts/
The twenty-one foot model is the one I think will work well enough for the NVIS antenna for the Virginia QSO Party. It would seem WonderPole has put some ...
hamchatforum.lefora.com/2009/11/16/nascar-and-sports-tailgating-flag-masts/
The book includes new content on Near Vertical Incidence Skywave (NVIS) techniques, phased arrays, S-parameters as used in modern vector network analyzers ...
hamchatforum.lefora.com/2009/11/16/the-arrl-antenna-book/

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