Spent most of this weekend putting into action plans for a better
antenna (both physically and electrically) which I have been drawing
up for some time.
The result - still an inverted-L -is a slightly higher vertical section, a
mast that does not need to be taken down in the wind, and three top
wires 0.7m apart at the vertical end and 1m apart at the far end.
The frequency dropped from 137kHz to 122kHz, a 12 per cent
change. I have not yet compared these with Dick's predicted
capacitance changes.
On receive it performs better with slightly stronger signals and less
noise.
On transmit, I was disappointed to get less current (even after a lot
of fiddling with the matching transformer). I expected more current.
My first reaction was to think that the antenna impedance had gone
up but I think that would be swamped by the earth resistance in any
case. Anyone got any ideas?
Reports from GW4ALG and G8RW appeared to show that it was at
least as good as my single wire top section, despite the current
reduction.
Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm
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