Dual Band Antenna

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Dual Band Antenna

Postby timcooper55 » Thu Jan 28, 2016 1:58 pm

Hi All,

Would some one be able to advise on best dual band antenna to put up please, a base station one which I will put up on a scaffold pole.

I have looked into making one, but plans I've found so far seem quite complicated unless anyone can advise differently!

Thanks

Tim
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Re: Dual Band Antenna

Postby m0lsx » Thu Jan 28, 2016 3:19 pm

I assume from dual band you mean 2 meters & 70cm. There are a variety of makes & of gains available. To a certain extent, the higher the gain the narrower the band, so if you want to use it for listening off the amateur bands the lower gain antennas are advisable & the alleged gains are open to interpretation & also of no relevance away from the specified bands anyhow.
Some of the more expensive antennas are better made, but that is not always the case or equal to the price.
Coax is probably the most important part of the system. Good coax will make or break the system, as it very very easy to loose almost all of the signal if using say 15 to 20 meters or more of coax between antenna & radio.
Personally unless you are really serious & have a specific use in mind which needs a specific type of antenna. I would say go for a £30 to £40 Chinese collinear, use decent coax & as you learn & develop, use your own experience & learning to choose & experiment with what goes best with your coax.
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Re: Dual Band Antenna

Postby timcooper55 » Thu Jan 28, 2016 5:06 pm

Hi mOLsx,

Thanks for reply.
It is the 2meters and 70cm bands, for tx.
Would you be able to kindly send me some links to some, as I can't see which collinear ones are Chinese.

Thanks
Tim
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Re: Dual Band Antenna

Postby G4RMT » Thu Jan 28, 2016 7:51 pm

Things like the Diamonds, and the others the bigger dealers sell. You can't really import these from China yourself because the size means the carriage is too expensive, so the UK dealers for once, are cheaper.

Do NOT use scaffold poles. 20ft(6m) 50mm ali tube is much lighter in weight, and perfect for aerials like these. Scaff poles weigh so much that many of the normal brackets and mounts cannot safely take the vertical load. The size of the wall fixings needs to go up, and there are practical things too - lifting a scaff pole up to the mounting height is damn hard, and from a ladder possibly dangerous, when you think that perhaps 4 to 5m of the length is above your head, and you have to keep it there while you do up clamps?

Even if you have them laying around, I'd suggest the cost of a bit of lighter weight tube could be well worth it. Scaff is also 48mm O.D. but that 2mm can make some clamps less rigid.
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Re: Dual Band Antenna

Postby timcooper55 » Thu Jan 28, 2016 8:09 pm

Hi GR4MT,

Thanks for reply and info on what brand antenna to get.
I hav'nt explained myself properly about using a scaffold pole.
The ones I have in my garden hold up the washing line. They have been there for years, and don't actually go into the ground themselves, but are bolted to two angle grind strips of metal which are.
I just have to loosen the bottom bolt, remove the upper bolt, then carefully swing the the scaffold pole down, then I can easily fix an antenna onto it at ground level.
If the pole wasn't already there, I would go on on your recommendation.

Thanks

Tim

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