Here is a first picture of my “fast activation antenna system” approach. The basic idea is
- focus on fast deployment and handling and see whether it is “sufficiently effective” for a SOTA activation with a small window of time on the summit,
- use a radiator as long as feasible (ca. 4.2m in my case and hence a lot longer than all ATX-1080 and similar),
- make a T1 tuner core part of the design for fast matching of unavoidable variance wrt feedpoint impedance due to differences in soil and radial placement,
- add a high-Q loading coil at the base (likely a lot lesser losses than the ones from the autotuner - currently ca. 10.5 uH at 0.05 Ohms).
It works very well so far! The performance varies - at 12:00Z with the radials deployed on snow RBN spots reported 26…31 dB SNR. On a muddy summit at (HB/GR-292) at 15:00Z, I had to fight to get an RNB spot and only got a 6…8 dB SNR report when I elevated one of the two radials.
I still have to investigate whether the main factor of influence are the ground losses (could be that the large area of snow on the glacier was in fact a very effective ground) or the relatively flat angle of radiation and the directionality of the antenna determined by the position of the radials (which is often given by the topology of the summit).
73 de Martin, DK3IT
