One additional point about this that I might not have expressed in enough
detail.
When a top hat with significant capacitance compared to distributed
capaciatnce along the radiator is involved, current tends to become very
linear throughout the radiator no matter where any loading inductance is
inserted.
Bjorn has a particularly extreme example for this, because the SRF of the
vertical without any inductor was 2.2 MHz.
<<The antenna is self resonant at 2.2 MHz and I use a coil wound on a water
bottle to bring it down to 1.8. The coil appears to be about 8-10 uH
according to online calculators.>>>
He only has 100 ohms of reactance-cancelling inductance, which further
proves his statement that the antenna SRF is 2.2 MHz. While the amount of
reactance has no direct bearing on distribution, the fact it is so low means
current is pretty much all flowing into the hat wires.
Series reactances do not change distribution above the reactance because it
is a series system. Shunting capacitances or reactances do. The only way
current can change is through an electric field and displacement currents.
The significant capacitance, in his case, is the hat.
The only two places where significant changes are possible without a
significant height increase are:
1.) reducing foldback of the hat
2.) improving the ground system
73 Tom
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