Brad,
A local ham uses an attic antenna. His is a approx 100' wire fed in the
center with ladder line to a tuner. He keeps the wire as far away from
metal as possible (other wires, AC ducts, pipes, etc.). To obtain 100'+
length the wire is bent around the outer portions of the attic. Imagine a
rectangle with a portion of one of the long sides missing. His house is
two stories so the wire is approx 20' above ground level. This arrangement
works well for him and he has worked many DX stations with it. His
preferred operating mode is FT8.
I don't think there is magic in the wire length, but longer wires gives you
a better chance of matching the antenna at lower frequencies. One big
issue with this arrangement is RFI both on receiving and transmitting. He
has found that 40 watts is the maximum power he can run without upsetting
his home electronics. In my opinion this approach
requires experimentation. Look at the frequencies on which you want to
operate, using what you know about antennas come up with a plan, install
the antenna, see how it works, modify if needed and repeat! Information
has been published on indoor antennas which you should be able to locate
via web searching.
Good luck!
Robie AJ4F
On Mon, May 16, 2022 at 7:32 AM Brad Anbro <n9en@live.com> wrote:
> Hello all,
>
> A new acquaintance of mine, who is a newly licensed ham, would like to
> install an HF antenna in his attic. In my 40+ years as a ham, I have never
> installed an HF antenna in an attic. I have installed many wire antennas
> outside in the open air, but none in an attic. I am guessing that he would
> like to end up with a dipole for 20 meters, so that he can get on HF and
> make a few QSOs.
>
> I am assuming that the antenna should be in the clear and as far away from
> the wood as possible. Is that correct? Also, is the required length
> appreciably different than a dipole installed outside in the air (468
> divided by the frequency in MHz)?
>
> Thanks for any help with this!
>
> 73 de Brad, N9EN
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