Hi Alex and all,
soon i'll measure exactly the antenna current, but one things that appear
in this discussion, is that the antenna work very well, it is only a single
wire 60 meters long about 1 meters far at the top of the tower, and about
25 meters far at the base.
I have read that wire near a tower has many losses, but this seems to
confirm the opposite, also the tower that i use in winter in Mantova have
the same wire antenna, little bit longer, and with only 100 W my signal is
perfectly audible in UK...
So, may be that the big tower act like a big additional vertical capacitance
to increase signal output??
I don't know, but shure the sistem work well!!
I'm listening at 136.100 now (21 Z) and i see a very weak signal/line at the
frequency, may will be Vlad??
73 de Giulio IK2DED.
Hi, David and Group.
Your conclusion may be right. But I say "if antenna curent is 1 A..." and
so on. Large resistance should decrease antenna curent and ERP should be
much lower. This is why one need measure antenna curent to estimate ERP.
Output TX power is not adeqate info.
Also, it is worth to take into consideration Giulio's relatively high
antenna (60 m!!!) Whithout top load this yeld 30 meters of effective
height. If there is very large top load then ERP should be 4 times grater!
If antenna height is 10 m (for example) then ERP is 9 times lower...
ERP is mainly determed by antenna current and efffective height. If this
is known then it is very simple to estimate radiated power. Certanly this
is very aproximative estimation. But something is better then nothing :-)
73 de RA9MB/Alex
http://www.qsl.net/ra9mb
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