The most difficult to deal with loss in a vertical antenna,
once it is 1/8th wave tall or taller, is in the ground
system. While it is possible to do something wrong, like
make the antenna out of a thin resistive conductor or use an
exceptionally bad loading system design, if even reasonable
care is taken or with reasonable selection of materials most
of the loss is in the ground system.
If the ground system is very good then there is almost no
difference at all between top loading, center loading, or
base loading. The exception would be a poor loading coil
design, for example a coil that was approaching
self-resonance at the operating frequency. A loading coil
self-resonant on 4 MHz would not be a good loading coil on
160 no matter how the inductor was constructed.
Follow the rules of common sense...use a big hat or
something with some self-capacitance near the top. Use
space-wound turns and a good form factor on the coil with
reasonable size wire. Use a good ground system. The result
will be almost no difference at all between a 150 foot
vertical and a 50 foot vertical.
Do things wrong and height can make a great difference.
73 Tom
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