My last post about the multiband halo was a bit depressing. I miss the antenna because when it worked I was very content with it. It might not be the ultimate DX antenna and hasn't much gain. But it receives well and it is almost omni directional. I decided to make a rebuild and solve the issues that occurred in the last 2 years. Luckily I've written some experiences in this blog that are now very useful.
Viewing the pic at the left. I fixed the "hanging" poles by uv resistant guy wires. Instead of using speakerwire, twinlead or ladderline I decided to go for a real halo design. Just to see what difference will occur. From publications I've read so far it is best to start with the highest frequency halo. In my case this will be the 12m (24MHz) halo.
Unfortunately the weather is getting worse these days. And I'm not having that much time. I've made the "core" of the antenna stronger and made all the necessary plastic items like distance holders last week after my work in the evening just before sunset. It gives me about an hour a day. This sunday I had big plans but when inspecting the house gutters I also found some other loose roof parts that had to be repaired before winter. Of course that was much more important. My intention was to get the antenna working before the CQWW next weekend but this will probably not happen. It doesn't matter much because I probably do a 10m single band effort again.
I wanted at least the 12m band halo be ready today. Luckily I had enough time for that at daylight. Above you see part of the construction. Wires are spaced about 4cm. The ends are tied into a point. It is a choice. It can also be flat ended. This was easier for me. When flat ended there will be more capacity between the ends in the end that will make tuning more difficult.
I already discovered a interesting feature. When I first measured the SWR/resonance the loop was a bit too large. Resonating on about 24.8 MHz. Bending wires back did not do the trick much. But shifting the plastic spacers back to form a sharper point brought the resonance up quickly to 24,9 MHz
The feedpoint is again made with the Diamond BU50 balun. I attached one wire to the balun and soldered 4 additional wires to that one wire each side. One for every of the 4 halo loops. I made everything as ugly as possible because ugly and messy antennas work best!
First measurement of the loop after I finished it. Not bad at all I think.
Length of the wire is exactly one wave length on 24,9 MHz. Of course it is too long as expected but you need some length for tuning. Next halo loop will be the 15m loop, it will have an effect on the 12m wire known from earlier experiments. I also need to keep in mind that resonance will shift up about 60Hz when mounted at top of the tower.
I'm curious how this new design will react on rain. With the speakerwire resonance shifted down. I hope rain will have less effect on this design because the loop wires are much more separated.
I also noticed that 12m was quite broad banded. I hope this will be the case on other bands as well.
