[TowerTalk] Cob Web Antenna

[John Tait]

Hi Gary.

I wrapped one vertically for 40m around the spreaders of my Quad a few 
years ago. It worked fine.  I also have a 20-10m G3TXQ version built on 
an old rotary clothesline. I chopped off most of the aluminium arms of 
the line, and then strapped fibreglass arms to the stumps, onto which I 
mounted the elements. The whole thing folds down, and fits nicely inside 
my car. I clamp it to an old pump up mast, and it works great as a 
portable antenna.

I prefer Steve's approach using the BalUn. The original design used 
folded dipole (T matched) elements, which was ingeniously simple, but 
not as re-producable as G3TXQ's design. The problem was that where you 
put the shorts, depended on the velocity factor of the twin feed wire 
elements. The VF depended on whatever wire you had to hand, so a lot of 
cut and try had to be gone thru' until you found the sweet spot for the 
short.

      The Cobweb clothesline could be put to good use where antennas are 
prohibited...A bit close to the ground, but a lot better than nothing. {;o)

                   Vy 73

                         John EI7BA


On 30/10/2017 12:05, Gary wrote:
> Martin,
>
>
>       I was thinking about a "reasonable" sized 40 meter antenna, which is why I started the thread. I was hoping someone would pop up and say they had done it.
>
>
> 73,
>
> Gary kk0sd
>
>
> ________________________________
> From: TowerTalk <towertalk-bounces at contesting.com> on behalf of Martin Sole <hs0zed at gmail.com>
> Sent: Monday, October 30, 2017 1:29 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Cob Web Antenna
>
> I think the Cobweb(b) antenna is an excellent antenna for limited space
> with usefulness as a second antenna for those with a bit more space.
> I've seen a lot of discussion about its use in the horizontal plane from
> 20m-6m. I have a couple of questions that might have simple answers.
>
> What happens when such an antenna is mounted vertically?
>
> Assuming vertical mounting is not massively detrimental, what happens
> when a second passive element of similar shape is added at a distance,
> ala 2 element yagi/quad?
>
> Most of the Cobweb style antennas I have seen stop at 20m yet they would
> seem an ideal way to get reasonable size antennas on 30/40m, I don't
> consider a full size 20m quad loop overly big. What's the catch?
>
> Martin, HS0ZED
>
>
>
>
> On 29/10/2017 10:13, Dan Maguire wrote:
>> KK0SD wrote:
>>>>> Has anyone actually modeled a Cob Web antenna?
>> More than you can shake a stick at.  See
>>
>> https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fac6la.com%2Faecollection9.html&data=02%7C01%7CW1JCW%40hotmail.com%7C4af03f009de944383ce208d51f5fa4b5%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636449418005637946&sdata=sC1LpLrAL7mFHFhGBoJuMlp97o2IenrnPg0ykk%2Bq%2FQU%3D&reserved=0
>>
>> Dan, AC6LA
>> _______________________________________________
>>
>>
>>
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