XPost: rec.radio.amateur.moderated

PE4BAS Amateur Radio Weblog

///////////////////////////////////////////
Experimental setup square halo

Posted: 06 Jun 2022 12:56 PM PDT https://pe4bas.blogspot.com/2022/06/experimental-setup-square-halo.html


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."

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)