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?