small/limited space verticals?

yes correct. I can add the UNUN (or anything, I even have lots of toroids and nice balun wire).

https://www.nevadaradio.co.uk/product/sigma-venom-58-wave/
here is another one.
Thanks

From the advert, it seems that 5.8m giives them a 50 ohm impedence and hence low SWR on 26-28MHz - not that, that helps us. Youā€™d be effectively using it as a ā€œrandom length wireā€ that of course away from resonance will NOT have a 50 ohm impedance, hence an UNUN and an ATU will most likely be needed to make it work broad-band, which I think is what you are looking for.

73 Ed.

Eventually it will break due to UV effects. Replace annually.

So I think Ill go with this. It will hold for longer I think.
Ill make the UNUN as I have one now.

yes this is my fear. the one I have now seems ok but its old!

You need to view some items as maintenance items. Expendable and will fail. So replace them every so many years (from 1 to who knows) before it fails so it is less likely to fail at random.

How much is a pole? Say Ā£15 and you replace it every 2 years. So you would be 17 years in to regular maintenance replacements before you spent what that first antenna costs. Would that last 17 years ?

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I replaced one last year after it snapped in a gale. It had been up for over ten years supporting an inverted V.

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hehe it makes sense from an economic point of view! Ill add some clumps to my pole as a test then!

Hi Tasos,

Without knowing what the matching arrangement is on the Thunderpole itā€™s difficult to predict what might be necessary to turn it into a multi-band amateur band antennaā€¦

There are so many variables involved, multi-banding is more akin to the Dark Arts than scientifically based design. The Sigma antenna obviously makes huge compromises, relying on a wide-range ATU to transform the presented impedance to 50 ohms. According to the blurb on the website this is on some bands outside the range of a built-in auto-ATU , a separate manual ATU being required (although it doesnā€™t tell you what you actually need to match!) The spec for the antenna quite amusingly states itā€™s impedance is 50 ohms :rofl:

They do make the point you need to use good quality coax - RG213 etc - coax feeder losses at high SWR can be considerable, this will apply to a commercial or a home brew version :wink:

Good luck with your antenna whichever option you chose!

73 de Paul G4MD

PS have had an Aldi fibreglass pole supporting an antenna outside for five years, took it down the other day and itā€™s in fine condition except for a bit of flaking paint.

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Iā€™d renew that paint, Paul, it is what protects the pole from UV. A can of spray paint from Halfords would be adequate.

A 5/8 wavelength antenna has an impedance of around (75āˆ’425j) Ī©. It needs a loading coil to be 50 Ī©. Advertising canā€™t change physics.

wunder

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