Cobweb Antenna - with 6m and 4m

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MrWeetabix
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Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

Morning all,

Recently got myself a new radio, which does HF, 6m and 4m but annoyingly it only has a single antenna connection.

I have been tempted by a Polish chap selling his own version of a Cobweb, but which comes with elements for 6m and 4m too.

s-l1600.jpg

The claim is that the antenna is omnidirectional (a normal Cobweb just about is) but the question is that surely can't be right when the 6 and 4 elements aren't long enough to form the halo shape

s-l1600_sml.jpg

has anyone had any experience with this type of Cobweb or made their own at all? looking for practical feedback before I sink cash on a new rotatable washingline.....

Thanks all
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Re: Cobweb Antenna - with 6m and 4m

Post by Auldgeek »

MrWeetabix wrote: 03 Sep 2020, 08:32 Morning all,

Recently got myself a new radio, which does HF, 6m and 4m but annoyingly it only has a single antenna connection.

I have been tempted by a Polish chap selling his own version of a Cobweb, but which comes with elements for 6m and 4m too.


s-l1600.jpg


The claim is that the antenna is omnidirectional (a normal Cobweb just about is) but the question is that surely can't be right when the 6 and 4 elements aren't long enough to form the halo shape


s-l1600_sml.jpg


has anyone had any experience with this type of Cobweb or made their own at all? looking for practical feedback before I sink cash on a new rotatable washingline.....

Thanks all
I have another make but it's essentially the same.
On 4m & 6m, they are just 1/2 wave dipoles with 90 degree dog legs and you're spot on, radiation pattern is not omnidirectional, rather they are, directional on 2 sides.

I'm disappointed in mine, as it's unusually noisy. I reckon it's due to the fact it's sitting just below roof height. If you do go for one, keep it as high above roof level as you can and if there's VHF yagis on the same mast, keep these well away from it, otherwise there's a high chance of strange detuning.
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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

I had considered making my own mini cobweb, covering just 6 and 4m but I can’t find any designs or anyone doing that. The closest I have found is either a nested Moxon design or there’s a vertically-mounted diamond one, again nesting the 4m inside the 6m one.

Surely the principles of a cobweb, but slimmed down to sub VHF sizes would work? 🤷🏼‍♂️🤔
26TM175. OP: Craig. QTH: Gateshead IO94EW. Also 163TM175 when mobile in Wales 8)

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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

Auldgeek wrote: 03 Sep 2020, 20:27
MrWeetabix wrote: 03 Sep 2020, 08:32 Morning all,

Recently got myself a new radio, which does HF, 6m and 4m but annoyingly it only has a single antenna connection.

I have been tempted by a Polish chap selling his own version of a Cobweb, but which comes with elements for 6m and 4m too.


s-l1600.jpg


The claim is that the antenna is omnidirectional (a normal Cobweb just about is) but the question is that surely can't be right when the 6 and 4 elements aren't long enough to form the halo shape


s-l1600_sml.jpg


has anyone had any experience with this type of Cobweb or made their own at all? looking for practical feedback before I sink cash on a new rotatable washingline.....

Thanks all
I have another make but it's essentially the same.
On 4m & 6m, they are just 1/2 wave dipoles with 90 degree dog legs and you're spot on, radiation pattern is not omnidirectional, rather they are, directional on 2 sides.

I'm disappointed in mine, as it's unusually noisy. I reckon it's due to the fact it's sitting just below roof height. If you do go for one, keep it as high above roof level as you can and if there's VHF yagis on the same mast, keep these well away from it, otherwise there's a high chance of strange detuning.
I have been thinking about the how directional it would actually be on those bands..... does this look about right?
s-l1600_Rad.jpg
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Re: Cobweb Antenna - with 6m and 4m

Post by Auldgeek »

MrWeetabix wrote: 04 Sep 2020, 15:55
I have been thinking about the how directional it would actually be on those bands..... does this look about right?

s-l1600_Rad.jpg
That's about right. I find with mine on 4m, the radiation pattern behaves more like a conventional dipole. I don't really notice the side lobes that much, as I see a distinct & clear nul when turning it side on to my desired direction. 6m is less pronounced, as the side lobes come in to play. This is likely due to more of the radiator after the 90 degree dog leg.

Under flat conditions, I use GB3ANG beacon and the nul is really noticeable on 4m. With the back of the antenna (where the feed box is) pointing towards your desired direction, there's a slight improvement compared to it turned 180 degrees.
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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

So are you having to rotate it to get the best from 6 and 4? Urgh.... wanted to avoid that.
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Re: Cobweb Antenna - with 6m and 4m

Post by Auldgeek »

MrWeetabix wrote: 04 Sep 2020, 21:52 So are you having to rotate it to get the best from 6 and 4? Urgh.... wanted to avoid that.
on 4m, yes. However, I have a dual band Yagi for 4m/6m, so for my needs, the additional bands on my Cobwebb are a bonus for local working.
Depends on what you intend to use the 4m dipole for.
Last edited by Auldgeek on 05 Sep 2020, 19:43, edited 1 time in total.
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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

Probably just 4M FT8 really. I have a vertical for 6m which has gotten me some amazing European contacts this summer so I will have to have a think about what to expect from 4m.... so go North/South for mainly inter-G or go with an E/W for Europe..... I'm in an odd spot up here in the North East to decide!
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Re: Cobweb Antenna - with 6m and 4m

Post by ch25 »

WE ARE MOTÖRHEAD, AND WE PLAY ROCK N' ROLL
You can't have too many antennas...
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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

Thanks for the link matie, but not looking fir a Yagi and having to install a rotator etc. This is why the cobweb 20-4 was appealing 👍
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Re: Cobweb Antenna - with 6m and 4m

Post by ch25 »

Almost omni, but with current propagation conditions I wouldn't bother.
Got 6m 5/8 and 6 element Yagi and most of the stations I work on Yagi are not existent on omnidirectional.
GL anyway.
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Re: Cobweb Antenna - with 6m and 4m

Post by MrWeetabix »

Well I have been using triband vertical since I came back onto the radio six weeks ago and I have worked most of EU and UK on 6m and also quite a bit on 2m with same ant.

A yagi helps, but its not the final word in having fun/dxing
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