[Lowfer] Ultimate LOWFER Transmitter?

[Steve Olney]

G'day Stewart and All,

Neither the radiation resistance nor the loss resistance is a real
resistance in the sense that you can't use simple circuit analysis to give a
picture of what is happening.    Radiation resistance is just a resistance
in which the power radiated appears to be dissipated.    The loss resistance
is just the resistance in which the non-radiated power appears to be
dissipated.   Some of this loss is "lumped" in the coil loss and some is
distributed in ground and environmental losses.

Taking your assumption that the "base" lowfer antenna has an 0.02 ohm
radiation resistance, a 20 ohm loss resistance (ground + coil loss), and is
tuned to be a 20 ohm resistive load at the operating frequency.    Assume a
50% split between ground/environmental and coil loss (10 ohm each).   This a
generous split to help your case as much as possible - mine system here is
about 90% ground/enviromental and 10% coil.  The efficiency of your example
is 0.02/20 = 10%.

Now split the single radiator in two but separated by, say,  just 1m with
each radiator having a series coil and joined at the base.    The radiation
resistance stays the same at 0.02 ohm,  the ground/environmental loss
resistance stays the same at 10 ohms, but the coil resistances are in
parallel and are reduced to an effective 5 ohms.    So now the efficiency is
0.02/(10 + 5) = 13.333%.   This is a gain of a little over 1dB - not 3dB.
Note this same gain could have been done more simply by just making the
original signal coil with less loss.     Increasing the spacing does not
alter this scenario as long as you are not running out of space with the
original ground system and the spacing becomes a significant fraction of a
wavelenth.   Putting a 100 radiators in parallel closely spaced would only
reduce the losses in the coil by 100 and so the limiting gain for this would
be an efficiency of about 20% (0.02/10).   This is a gain of 3dB maximum.
Note this is with the same amount of wire/netting/sheet in the ground system
for both scenarios.    Adding more wire/netting/sheeting for multiple
radiators while leaving the single radiator with its original
wire/netting/sheeting is not playing fair.

Much simpler to roll out the chicken wire as far as possible under your
single radiator system to reduce the ground losses,  fire up the chainsaw to
reduce the environmental losses (a.k.a. trees and bushes) and use as high a
Q coil as possible on a single mast.    Hey - isn't that what you guys had
done already ?

73s Steve Olney VK2ZTO

"Man made mathematics and models, but God made reality"