Experimental setup square halo

Finally there was some time to do some experiments with the square halo this weekend. A few hours because there was a weather change. 

First setup was 20m only:

PA9X told on his site this was quite easy, and it is. However the balun in the white box I showed previously didn't make things easy. I was not able to get a decent resonance and suspected the homemade balun. It was exchanged for a commercial Diamond BU50 balun. After that it was easy to tune the wire.

At first I was planning to put this in the tower and test how things would work. But I changed my mind and went to the next band. 17m was a pain. I could not get any resonance at all. It went better when I opened te ends of the wire, so it was just a half wave dipole. But still best SWR at resonance was about 1:2. Not shure about it but I decided to remove the wire and go on the the next band which is 15m.

This actually went well. Easy to tune. 20m not affected at all. But have to write both bands are quite narrow. Bandwidth about 200 KHz with SWR below 1:2.

Again tried the 17m wire. But still impossible to find a decent resonance or SWR "peak". Not shure how to solve it. The "loop antenna wiki" has something about halo antennas written. It is about the gap at the end. It is capacitively coupled. I might try to test if the ends of the wire should be closer or further away from each other. If any reader with more antenna knowledge has any idea?

The weather changed shortly after and it is now pouring wet. Good weather to be in front of the radio. But not for building antennas. I will solder and seal the 20m/15m wire now for permanent use. Hopefully there will be some more time to do some further experiments. My ultimate goal would be a omni directional horizontal small antenna for 20/17/15/12m which you don't have to tune much.

Update 07-06-2022: I found some info about the capacitive gap in relation to the resonance of the antenna like we try to design. It turns out that my thoughts were right.

http://on5au.be/content/a10/wire/ilzx.html

Cebik W4RNL writes:

"For a multi-band antenna, you may have better luck separating the bands. 20-15-10 provides less element-to-element interaction than a 5-band version of the antenna, although the harmonic relationship of 20 and 10 meters may show some pattern deviations. Of course, a second smaller array for 17 and 12 meters makes a good antenna to stack on top of the tri-band model."