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We'd like to install an antenna for 80m at our club/contest station. Our club, OH2K, is housed at a school, and we can't fill the roof with a radial mesh. The roof is not metallic itself, either. We already have a horizontal dipole, but would like to have something with a lower radiation angle.

We do have a 20-meter tower on the roof of the school building, but there are no guy wires attached to the top of the mast, so it's a bit hard to support a full-height 20-meter-long quarter-wave vertical. However, something in the 10-15 meter length range is easy to hang. A very short vertical would be too narrowband for contests.

We operate multi-multi, with 1 KW linear amplifiers, and stub + bandpass filters.

What practical 80m vertical antenna designs should we look at?

Kevin Reid AG6YO
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oh7lzb
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2 Answers2

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An angled full-wave delta loop can be hung from the tower at the height you are talking about and is very broadbanded (and can be fed from a corner so that it is vertically polarized. An advantage is that this also makes a very good receive antenna. See for example the October 1984 QST for an article on the subject.

Bill - K5WL
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In your situation, I would shunt feed the 20m tower on the roof and drop one 20m wire from the roof if the building is tall enough. If the building is lower than that, you can end the wire in a T-shape, and/or load it or, alternatively, complete the return path by installing two or more elevated radials. Loading will lower the bandwidth of the antenna significantly, though.

Shunt-feeding offers the advantage that you can earth your roof tower for proper lightning protection.

If you feed with coaxial cable, do not forget to also install a sheath current choke.

on4aa
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