Mike Dennison wrote:

DK8KW wrote:
> On the other hand, there is Vaino's (OH2LX) comment, that according to his
> long-lasting experience it is not possible to estimate a station's ERP
> from the field strength at a far distance ...
>

Well, that's the point I was trying to find out. I wondered whether I
could calculate my ERP from your graph, and plainly I could not.
But is this Vaino's theory, or something else. If we could sort this
one out, it would validate (or more likely quantify) Mal's comment
that 1W ERP from a small antenna will be worse than the same ERP
from a large one - at a distance of course

Good suggestion and basic theory/practical applications dictates that the
higher antenna must certainly be better in all respects. You must already have
heard about the amateur who loaded his LF rig into a 10 km farmers fence and
got the perfect match but  COULD NOT RADIATE  THE SIGNAL BEYOND A FEW METRES.
Had he used a vertical antenna configuration at say 40 meters high he  would
have radiated the signal possible 2000 k/metres and more. Commercial stations
even with their MEGAWATTS use extremely high antennas towers up to 350 metres
and maybe higher. Why do they bother if they could get away with a piece of
wire a few metres above the ground.

The league table approach separates the MEN from the BOYS hi !!! and hopefully
encourages the BOYS to get into MANHOOD !!!!!
You do not need a lot of REAL ESTATE for vertical antennas, a few square metres
is all that is  required, any small back garden is ideal. A 5 section STRUMECH
100 ft tower has a base area of 1metre sq. - No more excuses about small back
yards.
73 de Mal/G3KEV

All very interesting indeed. Although some people dislike the league
table approach, I personally find these measurements very useful in
my own ongoing efforts to get a good signal out of a small garden.
And comparing my efforts to those of other people is a good way to
keep up my enthusiasm to do better.

Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm