If I place the
inductor at the feed point all the current must flow through it, maximizing
loss. If I place it at the top little current flows through it, minimizing
effectiveness. If I distribute it the antenna's resonance is broader, but at
what cost? Lower Q. The signal strength is less. So I make the coil as short
as I can, put it in the middle and it's juuust right.

73, H. NQ5H

Simple rule, as mentioned in ON4UN book, the efficiency of the antenna is
proportional to the area under the current curve. When you model the antenna
and view the current distribution and compare various cases with coil
positioned at bottom, middle, top, it is obvious why. It also shows why it is
important to understand the role of the loading coil and its effect on the
current distribution along the radiator. This effect gets magnified when using
loaded elements in parasitic beam designs. If you use "zero" size inductance in
modeling, the results are "too good" and correlation with reality is way off.
That's what is all about.

Yuri, K3BU.us