80M vertical

As the station property was acquired in summer of 2020 the first participation that took place was CQWW SSB in October. The operation was completely field day style SOSB80 LP! category (what a torture). LZ1JER helped me erecting standard 1/4 wave vertical with elevated radials on 22m Spiderpole and laying down two BOGs (NE and NW directions), ~56meters each. Wasn't really sure what to expect from the receiving antennas but at least they kind of performed - something that was not so true for vertical. Not that it didn't work at all but was way too narrow and I could barely move around the band without utilizing ATU. While this somehow worked for 100W, it was clear that this is not a solution that would work in SO2R scenario and/or high power.

After a post-contest conversation with LZ4AX he came out with proposal to make longer vertical section and shorten the radials. Doing so would contribute to the unbalanced antenna nature but would also contribute to wider antenna bandwidth and better feedpoint impedance. Another advantage would be that feedpoint is offset from the highest current region and this would tolerate better differences in radial system (although the same size, radials are never equal in terms of impedance). So, after some modelling it turned out that we should be able to achieve 125Khz SWR 1:1.5 bandwidth or 230KHz SWR 1:2 bandwidth on 80 meters! The next logical question was how do we put 23 meters of wire on 22 meters high Spiderpole and still have 2 meters between feedpoint and ground so we make elevated radials? Well, use insulated wire (insulation contributes to velocity factor so it makes the wire about 5% longer) and wound the wire over the top Spiderpole sections (2-3 turns per section is OK). On the other hand, the radials were made of 12 meters insulated wire each so pretty easy to install. Also, don't forget that now you have quite unbalanced antenna, so a good choke is a must! The one that I've made consists of 8 turns RG-316 cable on FB-31-1020 core.

This vertical antenna worked well during CQWW CW 2020 with 700+ watts.

We all know that "a picture worth thousands words" but unfortunately I didn't make enough during the preparations. Still, if you zoom enough the only photo here you will see how the vertical wire twists over the upper part of the Spiderpole. Also, yellow traces that are visible are the radials. Last but not at least you will find a MMANA file to download and play with at the bottom of the page!