For this, Ian is using 5W input into VK3MO, a 4 x 5 element Yagi array on a 200 foot tower, and the same input into VK3QN, a 2 x 6 element Yagi array optimised for very low angle radiation, on a 66 foot tower.
For this comparison, both antennas are beaming long path to Europe, so my results are based on reception during the breakfast time period here.
The following plot is typical of each morning's results:
Very interesting that the low angle optimisation of a 12 element array achieves a received signal during long path that is nearly double the strength of a 20 element array, even though the former is at considerably lower height overall.
5 comments:
John, do you always get two peaks from the VK3 stations? If so, why?
Hi John. Thanks for your interest. The short answer is: 'yes'. The first eak comes a pretty consistent ~40 minutes before the second. As to what causes this, I'll have to think some more and write a post about it. But I am not expert on propagation!
That's interesting John about the two peaks.
For reference and you can verify this yourself. Both stations were in Kyneton, Victoria. Their local sunset was at 17:53 local. Their time is UTC +10 hours so their sunset was at 07:53 UTC.
Is your chart in UTC or Summertime?
I was wondering if it had something to do with short path and long path? Two peaks? I'll have to look for more info on it.
John, yes, both stations are operated by VK3MO; VK3QN is Ian's wife's callsign. Chart is as spots are received, which are always UT. Long path is responsible for the peak morning signal in general. The 'two peaks', which are not always so pronounced but are present, is likely to be some mix of paths. Try an area prediction in 'Proppy' or similar, and marvel at the counterintuitive paths that may be involved. I can confirm, through seaside experiments in the morning from W and E coasts, that the VK3 signals are coming from the western hemisphere, so certainly LP.
Very surprised that the two lower antennas outperform the stacked 200ft array as I would have presumed that the higher stacked array would have created a variety of radiation angles that would have given a more stable signal on the long path... Presumably the long path is very dependent upon the dominant very low angle signals from the optimised lower antenna set up from these results, a fascinating experiment! ... Dave G4AKC
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