Experimental multiband halo rebuild (3)

 And again the weather was fine today. Lots of sun and a reasonable temperature. Good for antenna work.

As I wrote before this experiment has a different approach. I use thicker isolated wire and make a real halo instead of using "speakerwire" which is not really weather resistant. To the left you can see the feedpoint with the Diamond BU50 1:1 balun.

After experimenting for over an hour I decided to drop the 12m part of the antenna. Whatever I did I could not get 12m right. It doesn't really matter I can also use 12m on my Gainmaster 1/2 wave 11m antenna with the internal tuner from the radio. And it does at least as good as a 12m band halo. The 17m halo was too short so I made it 40cm longer and that was a good choice. 17m is excellent now.

I made everything as ugly as possible, since ugly antennas work the best :-)

Not to forget this is the open side of the halo on the picture at the right. It is most important because this is were you can tune the antenna. The problem is that if you tune one halo others will change as well. It takes a lot of time to get things right. While tuning I kept the change of resonance point, when mounting it high on the tower, in mind. It expected it to shift upwards and I wrote about it in previous posts. I wrote down the most ideal "best" frequencies and tuned the antenna on lower frequencies for compensation.

The nice and easy thing is that, instead of folding back the end of the loops, tuning can be done by changing the angle of the halo ends. 

Steeper angle at the end: resonsance frequency shifts down.

Not such a steep angle: resonance frequency shifts up.

Depending on band the change can be 100-200 Khz.

The results on the ground before mounting it in the tower again:

I thought it was good enough considering the resonance shift upwards which I noted in my post about finishing it the last time with "speakerwire". So, I mounted everything into the tower.

Unfortunately the shift upwards did only happen on 17m as expected. On 15m the shift was larger as last time and on 20m the shift was downwards. That's the fun with experiments, you never know what will happen.

15m band: best frequency on 1m height 21.173 MHz, at 14m height 21,404 MHz (231 Khz shift up)

17m band: best frequency on 1m height 18,046 MHz, at 14m height 18,122 MHz (76 KHz shift up)

20m band: best frequency on 1m height 14,117 MHz, at 14m height 14,092 MHz (25 KHz shift down)

Information above is written down because I need it when fine tuning the antenne when I have the tower down again. 

The antenna is very good usable partly with the internal radio antennatuner. I had 1,5 hour before dinner and decided to go for the ARRL SSB DX contest. On 15m it was easy to work for instance the state of Washington and California which are normally not easy to catch. On 20m things were very quiet but I worked a few from the USA anyway. Most stations were present on 10m. Of course I used my 4 element LFA there and struggled to find a good frequency for running. I did a combination of running and S&P and worked 115 stations from 43 states in 1,5 hours, good enough for me.

Experimental multiband halo rebuild (2)

  The weather here is improving. Sun is shining and temperature today was about 7C (45F). My XYL wants the antenna away from the garden. I agree with her. But experiments take time.

From what I read in other building descriptions on the internet you should start building with the highest band. So I started building the 12m loop last time. Fast forward....next time I wil start with 20m again. It turns out after I made the 20m loop all other loops are way too short. Have to fix that hopefully tomorrow.

Also the glasfiber is bending too much due to the heavier wire. I already attached guy lines on top. I need to adjust them in the end.

The result so far:

12m is way too short and also SWR is not what it should be.

15m too short

17m too short, SWR/resonance very nice

20m is fine.

Hopefully the weather will be good enough tomorrow to continue tuning the antenna.