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Re: Less Than Perfect Antennas

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Charlie T, K3ICH

Re: Less Than Perfect Antennas

I wonder if anyone has ever tried, for want of a better name, a "Skeleton
Cone" which consists of a single horizontal wire connected to the coax
center conductor and two sloping wires at 45 degrees, in the same plane
connected to the coax shield. A true Discone antenna would have many
(typically eight each) horizontal and sloping elements. I'm guessing many
of us have used the VHF/UHF version for very wide band coverage, for
example 144, 220, 432 MHz and even higher. I know I have one up and it
performs as well as a regular single band ¼λ ground plane (unity gain)
on all three bands with low SWR. The ICOM version as well as a few others,
also have a loaded whip for 52 MHz mounted on the bushing that the
horizontal elements are screwed into.

I'm also guessing the formulas for a true Discone would work for a
"skeleton" style as well. I Since it is inherently a wide band design, the
actual lengths are probably not too critical. I've heard this type antenna
described, but I don't remember where or how well it supposedly worked. It
obviously requires two supports, high enough that the sloping wires ends
are off the ground by a bit.

73, Charlie k3ICH

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David Gilbert

Re: Less Than Perfect Antennas

Interestingly enough, I played around with modeling that very thing in
EZNEC+ a few weeks ago. I wasn't able to get it to work worth a damn
without more wires both in the top section and the skirt. I'm not
saying it can't be done, but the modeling I did wasn't very
encouraging. If anyone has had more favorable experience, whether model
or actual, I'd be willing to give it another try.

Dave AB7E

On 12/7/2018 3:29 PM, Charlie T wrote:

> I wonder if anyone has ever tried, for want of a better name, a "Skeleton
> Cone" which consists of a single horizontal wire connected to the coax
> center conductor and two sloping wires at 45 degrees, in the same plane
> connected to the coax shield. A true Discone antenna would have many
> (typically eight each) horizontal and sloping elements. I'm guessing many
> of us have used the VHF/UHF version for very wide band coverage, for
> example 144, 220, 432 MHz and even higher. I know I have one up and it
> performs as well as a regular single band ¼λ ground plane (unity gain)
> on all three bands with low SWR. The ICOM version as well as a few others,
> also have a loaded whip for 52 MHz mounted on the bushing that the
> horizontal elements are screwed into.
>
> I'm also guessing the formulas for a true Discone would work for a
> "skeleton" style as well. I Since it is inherently a wide band design, the
> actual lengths are probably not too critical. I've heard this type antenna
> described, but I don't remember where or how well it supposedly worked. It
> obviously requires two supports, high enough that the sloping wires ends
> are off the ground by a bit.
>
> 73, Charlie k3ICH

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Don Sanders

Re: Less Than Perfect Antennas

In reply to this post by Charlie T, K3ICH

While in Ecuador I tried this skeleton discone. Did not work well.
Actually I had to extend the lower wires from formulas by about 30 %
to get a low <3 swr at design freq, 40 meters. I did not try adding more
wires.
I had several good antennas I made so I did not do further investigations.
Dr. Don W4BWS

On Fri, Dec 7, 2018 at 5:30 PM Charlie T <[hidden email]> wrote:

David Gilbert

Re: Less Than Perfect Antennas

The EZNEC+ model I did showed the same thing ... the two lower wires had
to be much longer than I expected in order to get even a moderate SWR.
The pattern looked awful even when I did so.

73,
Dave AB7E

On 12/8/2018 4:49 AM, Don Sanders wrote:

> While in Ecuador I tried this skeleton discone. Did not work well.
> Actually I had to extend the lower wires from formulas by about 30 %
> to get a low <3 swr at design freq, 40 meters. I did not try adding more
> wires.
> I had several good antennas I made so I did not do further investigations.
> Dr. Don W4BWS
>
>
>
>
> On Fri, Dec 7, 2018 at 5:30 PM Charlie T <[hidden email]> wrote:
>
>> I wonder if anyone has ever tried, for want of a better name, a "Skeleton
>> Cone" which consists of a single horizontal wire connected to the coax
>> center conductor and two sloping wires at 45 degrees, in the same plane
>> connected to the coax shield. A true Discone antenna would have many
>> (typically eight each) horizontal and sloping elements. I'm guessing many
>> of us have used the VHF/UHF version for very wide band coverage, for
>> example 144, 220, 432 MHz and even higher. I know I have one up and it
>> performs as well as a regular single band ¼λ ground plane (unity gain)
>> on all three bands with low SWR. The ICOM version as well as a few others,
>> also have a loaded whip for 52 MHz mounted on the bushing that the
>> horizontal elements are screwed into.
>>
>> I'm also guessing the formulas for a true Discone would work for a
>> "skeleton" style as well. I Since it is inherently a wide band design, the
>> actual lengths are probably not too critical. I've heard this type antenna
>> described, but I don't remember where or how well it supposedly worked. It
>> obviously requires two supports, high enough that the sloping wires ends
>> are off the ground by a bit.
>>
>> 73, Charlie k3ICH
>>
>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Post: mailto:[hidden email]
>>
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>> Please help support this email list: http://www.qsl.net/donate.html
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Ignacy

Re: Less Than Perfect Antennas

In reply to this post by David Gilbert

I used about 90 ft of wire 20 ft up and 2 20 ft sloping radials, all
connected to K2 directly. I was able to work many stations on 80m SSB in a
200 mile radius.

All wire "concoctions" can be treated as a dipole but not necessarily fed in
the middle. So they are likely 1) very inefficient when fed by coax 2)
require a balun because of off-center feeding especially if the radio is not
battery operated, 3) are not good for DX unless they are high enough, and 4)
they may be directional where they are > 1/2 wave because of strong lobes.

Ignacy, NO9E

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