40m Hamstick, trampoline groundplane

My kids have a big trampoline in the backyard, and its built from a massive metal frame. In the beginning I joked about turning it into a magnetic loop antenna, but have settled with using it as a ground plane/counterweight for some antenna experiments. I’ve done 17m and 20m verticals with this one without problems!

This time I wanted to try a set of Hamsticks I’ve had around for a while, and I started out with the one for 40m. The bracket was secured with an old hose clamp and exhaust clamp.

Now, these antennas are known to be narrow banded, so my goal for this experiment was tuning it to the FT8 frequency and leave it there. The tuning process may require some patience and just the right tongue angle, especially at this height. However, after a couple of attempts and with a little help from my NanoVNA, I got as close to 7.074 MHz as I could. The NanoVNA claimed an SWR=1.15 which is way better than anticipated, and the FT-950 in my shack agreed. No tuner, neither internal nor external, was used.

Time to run some tests!

I ran a couple of FT8 QSOs really quick with 50W, and received reasonably good reports from a couple of stations, so this looks promising.

I also have Hamsticks for 30m and 60m, so this is fun to play with and I might eventually try them all on this setup. They’re not as visually intrusive as many other antennas either, so fingers crossed – maybe the XYL will let me have this one up for a while.

Here’s a picture of the complete setup. With the trees, branches, and twigs, maybe nobody will care if it’s there.

I’ll keep testing this antenna the next few days, if you catch me on 40m (or maybe 30/60m?) there’s a fair chance it’s happening with this trampoline/Hamstick antenna!

Update: I’ve worked the antenna for about an hour, and I’m quite satisfied with the results. I was heard from JW (-10dB) and all the way down to VK7 (-14dB). Unfortunately I had work the next day and couldn’t wait for the grayline to hit the yanks – maybe I’ll try again later, one early morning.

Update 2: Finetuned the antenna a bit more, and I’m now down to SWR=1.1. Working Europe is no problem, and with the help of the greyline I’ve had QSOs with Australia, Indonesia, China, Brazil, USA, and Canada. All FT4/FT8, but I’m still slightly overwhelmed.

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