Hello LF group,
I just want to share my last findings in the chase of "the missing dB's".
Yesterday I changed the antenna ground plane and added 10x6 m chicken wire
around the antenna base plus 12 radials 20-25 m each. The chicken wire was
solderable with a 300W soldering iron.
The feed impedance went down from 25 to 22 ohm. Not very much difference.
I have not used radials before, just a 8 m steel pipe + a various other ground
connections in parallel.
Today's measurements however show a noticeable improvement of 1,6-2 dB (with
the same antenna current).
Now, after all, the estimated ERP seems to correspond with measured values.
Interesting that the ground plane in some way improves the far field signal.
(BTW, the cost/improvement factor is 400 SEK/dB + 5 working hours. (400SEK=46
More details on my home page: http://home5.swipnet.se/~w-54761/fs.htm