Sunday, August 28, 2022

Experimental setup square halo (4) - into the tower

 It has been a while. I always think that when vacation arrives I will have a ocean of time. But real life is totally different. Anyway, I had a few hours to spend today. I dismantled the 6m/4m duoband beam and installed the experimental square halo after another final check. The only thing I changed is the boom, it is the same material (glasfiber) but shortened it and taped it with black tape. 

Above a picture to compare the size of the halo with the VHF duoband beam. The halo is small, excellent for the HAM without a lot of space. Not that I have a space problem but I really find this antenna interesting to experiment with.

 The experimental halo above the 10m LFA. Really small...will it work? The vertical antenna is another experiment for CB use, it is not working like it should yet.

I observed and noted the SWR at groundlevel and up on 14m height. The resonance point and SWR will shift higher in frequency, something to consider when you would like to experiment with this antenna.

Best SWR at 1m height: 14.120 - 18.142 - 21.116 - 24.931 MHz

Best SWR at 2m height: 14.177 - 18.150 - 21.130 - 24.942 MHz

Best SWR at 14m height: 14.250 - 18.200 - 21.200 - 25 MHz

So I need the tweak 17m and 12m a bit, though SWR is good enough to transmit. But is it working? I started on 12m late in the afternoon.

Unfortunately PSK reporter is not reporting everything these days. QSOs made with HC1HC (Ecuador), ZR6JT (RSA), YV5MHX (Venezuela).

Next 15m:

QSOs made with K1JZA (USA), 4Z5UY (Israel), DJ1TO (Germany), W6NWS (USA)

Next 17m, I was worried about this band because I don't use a closed loop in the antenna. It is kind of a dipole with a parasitic element of same length of the dipole attached. Best SWR 1,7:1.

I really don't know if propagation is good or bad? But I worked VE4GV (Canada), BG0BG (China), K0IEA (USA), OZ1RH (Denmark)

And at last 20m. I did some tests comparing the 2x20 inverted-V doublet with the square halo. I have to write the halo is clearly the winner. It wins on every signal. Previously the inverted-V was the winner compared to the multiband vertical. I'm really surprised by this small antenna. It is also very quiet on receive compared to the vertical. I had only time to test 20m late in the afternoon and in the evening.

I'm not really a fan of FT8 on 20m. I didn't had much success on this band previously as it is very crowded. I was really surprised by the DX contacts I could make this evening. I worked RW4D (Russia), EA1FK (Spain), EP5CHD (Iran), N4OPI (USA), W8NET (USA), W8QZM (USA), LW4EAZ (Argentina), K4YT (USA), W7DO (USA), CP6UA (Bolivia), CX1NU (Uruquay), D2UY (Angola)

Yes, this small antenna is working well for me. Is it special? Many HAMs told me this is just an cobbweb design. Yes it is, it has almost the same size and looks like a cobbweb. But it is different since it uses full size loops instead of half wave dipoles. Except for 17m that is, I couldn't get a decent match for 17m when I use a full size loop for that band. Instead I did cut the ends of the loop and what left is a dipole with a parasitic element, strange enough it works. That's the thing with experimental antennas, it works or it doesn't. This time I was lucky.


VE9KK said...

Good morning Bas, the new square halo antenna seems to be working very well. I was shocked to see the SWR change as you elevated the antenna. FT8 seems to be the way to go for checking antenna performance these days as there are a huge amount of stations listening.
I have given up on the reverse beacon network as it is very on and off with reports. Regarding FT8 I also find Ham Spots to be very good as well.
73 and enjoy your antenna experimenting,

PE4BAS, Bas said...

Hello Mike, tnx for you comment. Yes overall de SWR and resonance shifted up about 200KHz, something to consider when building this antenna. All depending on the installed height of course. I have not tested the antenna yet on SSB and CW. But I guess it will perform well. The idea is to tweak it a littyle more on 17m and 12m. After that I probabely connect the automatic tuner below the antenna to compensate the loss on TX in the long coax run to the shack. Although I doubt it will give me another 1dB on TX which is not noticable. However I need the tuner for a similair future experiment and so this will be just another experiment to see how well it will be working. If you ever consider to change your endfed setup I can highly recommend building this antenna. It is very small. No doubt it could fit in a attic as long as the roof is not insulated with alu foil. 73, Bas

Alexander PE0ALX said...

Wow, the antenna really works when looking at the contacts you made. Something for me to consider this antenna in the future sometime.

Alexander PE0ALX

PE4BAS, Bas said...

Hallo Alexander, ik raad je deze antenne aan. Maar het is wel zo dat wat voor mij werkt voor jou heel anders kan uitpakken. Ik moet wel zeggen dat deze antenne mij boven verwachting verrast heeft. 73, Bas

MadDogMcQ said...

Good morning Bas, that was an extremely interesting read - I very much enjoyed it and was inspired by your antenna experiments and amazed at the results too. Looking at your success on PSKR makes me want to move house where I can have a tower and not be limited to a simple wire, boo hoo :-(

Regarding time, yes I know how you feel. I recently had 16 consecutive days off work and I had sooooo much planned. But the time went by way too quickly and I hardly got any of my projects done.

Best wishes to you.

Tom, M7MCQ.

PE4BAS, Bas said...

Hello Tom, this antenna doesn't have to be in a tower. I happen to have one but it is a very small size antenna and certainly works very well on both RX as TX. It only takes some practical skills to make one en some experimenting to get things right. Time is always an issue here. Some have commented I should spend the time I write my blog at my radio instead. However, blogging is part of my hobby and most of it is written at lunchbreaks at my job. 73, Bas