Yuri Blanarovich, K3BU wrote:
"Have you figured out how to model loading coil of particular
inductance and physical size to reflect the real current drop across
it?"

Current drop across a coil is E/Z where Z is complex. If a reflection is
involved in the antenna, there are multiple Es involved, perhaps.

Growing or shrinking current through a coil, generates a voltage which
opposes current in the coil. Because of its opposing direction it is
called "counter emf". The change in current in the coil generates the
counter emf. A steady d-c current in a coil generates no emf.

A given length of wire has much greater counter emf when coiled than
when stretched out straight. We say it has more "inductance". It`s
because fields from close-wound turns intercouple. With 3 turns
closewound in a coil, 3 times the lines of force cut 3 turns, so 9 times
the counter emf is generated. As a first approximation, the inductance
varies as the square of the number of turns.

Opposition of counter emf in a coil delays the rise of current in a coil
from the phase of an a-c voltage. In a perfect coil with no resistance,
the delay is 90-degrees or 1/4-cycle. Resistance, useful or useless,
reducees the current delay. Due only to the L/R ratio, the phase delay
imposed by a coil can vary from 90-degrees down to zero.

I did a web search on "r.r.a.a" which produced 590 hits. One of these
was something posted by Roy Lewallen entitled "Inductor Operation". Roy
had measured phase delay in a loading coil. If I understood Roy, he
found no phase delay in an antenna loading coil.

In my opinion, he should find delay even in a coil feeding a dummy load,
especially if the coil is large as compared with the dummy load.

Best regards, Richard Harrison, KB5WZI