VK2ZTO wrote:
Suffice it to say as far as the practical case wrt to antenna heights for amateurs and the observation that a lower antenna can work better, I remain convinced that those observations by others have merit.
Steve, you don't have to devalue the observations, incomplete as they may be, they could be explained for instance by path length. Roger's graph shows clearly that at shorter path lengths, higher elevation rays are involved.
Es works on 7MHz, probably the reason for patchy but astonishingly good short path propagation in recent weeks. Though some call out the end of the solar cycle as the cause, it is probably Es, and the geometry of Es paths to someone just 150km away is a VERY high path.
Roger's graph indicates that if you want to work 2000+km paths on Es, gain right down to almost 0° elevation is relevant.
Whilst we stare at modelled antenna patterns over horizontal ground, the type of ground affects the pattern, but if the ground is not level, then the whole model needs to be rotated by the ground slope... and it may be that for some locations, the major lobe of the antenna is extremely low, possibly negative. I think of other cases such as Norm Deitch's configuration at Port Kembla where the path to the USA was over water, and the antenna was on a tall tower close to a high cliff at the water's edge.
I think that the thing that emerges is that if you want to work the longest Es paths, antenna height is always an advantage to those longer paths because the antenna gain at the lowest ray angle(s) suits the very acute ray arrival at the most distance Es patches which increases MUF (so you will see an opening that other closer in stations do not). This, though a lower antenna might compare more favourably on a shorter path, especially in the presence of higher f0Es.
That is not to say you won't get QSOs on a lower antenna, you will, just the probability is you will get less on average over time. This highlights the folly of those who cite a QSLs as evidence than an antenna "works".
Statistically, you could try to explain that the reason why stations with bigger erections get more contacts is that they are serious and spend more time at it. That is likely to be a factor, but I think that size matters.
Owen
PS: speaking of solar cycle transition, about 80% of the days of the first half of this month have been spotless.
