Regulars will know about the DX Commanders very cool results which are now filtering through in real world successful contest scenarios.
My own issue is that I needed just one antenna that would deliver an all-band solution, certainly for the contest bands of 40m, 20m, 15m and 10m – but I also needed 80m in the mix too.
My holiday home has a very compact small garden so the option of putting up a dipole for 80m is out the question, but modelling suggested than exchanging the 30m element for an inverted L for 80m should work.
The 80m element therefore starts vertical, like all DX Commander elements and turns a sharp corner at 6.9m above ground and droops down for around 13m or so, hanging over a bush at around 3m off the ground. Probably not perfect but perfectly adequate to score 44 QSOs inside an hour on the Saturday eve of the IOTA contest. That score includes 16 different IOTA multipliers, certainly a wide spread around Europe.
The antenna tunes from just over 3.65 right up to 3.78 under 1.5:1. Software modelling suggested I should have had a higher SWR due to some anticipated low impedance. It turns out that I was getting pretty close to 50 ohms.
For this build, I fitted 6 “pure” elements for 80m, 40m, 20m, 17m, 12m and 10m to give me all-band performance that doesn’t require an ATU totalling 9 bands that cover 80m, 40m, 30m, 20m, 17m, 15m, 12m, 10m and 6m.
ATU notes:
30m: What about the ATU for 30m? Well 30m band is almost (not quite) a third harmonic of 80m band, clicking the ATU brings the SWR down from about 4:1 to a match instantly. Good news for casual operation.
6m: Yes it’ll work on 6m too at around 2:1 SWR. However you will achieve around 1dB gain at 5 degrees take-off angle. Seriously, that’s fine. Most antennas at 5 degrees have a negative figure! Anyway, suggest you click in the ATU for casual 50 MHz fun so you can use all your power.
Using 15m: Why don’t I use a dedicated element for 15m? I don’t need to. The 40m elements works great since it’s 64% due to the 40m element coming back on itself about 1.5m. I’ve written about this before and a deeper explanation is in the DX Commander Manual. Excellent performance was achieved on 15m over the IOTA contest weekend scoring nearly 70 contacts on the Sunday morning alone, all over Europe. In fact, it was very nearly my most successful band with barely a flicker on the SWR meter.
Anyway, I was delighted to be able to achieve 80m!