On Jan 2, 6:31*pm, wrote:
I've been using 4Nec2, a freeware antenna modeling program based on
NEC-2 (Numerical Electromagnetic Code). I'm wondering if anyone could
provide some insight as to just how it models current at the ends of
wires that are not connected to anything (a.k.a. "free ends" or "open
ends").

Does NEC-2 model "end caps" at free ends, which is equivalent to
assuming wires are solid, or does it just set the current equal to
zero at the free ends, which is equivalent to assuming wires are
hollow? Is it possible that it does both, but the specific model is
determined by the choice of computational kernel (extended vs.
standard)?

I've tried looking through some of the NEC-2 documentation, but I
can't find a definitive answer.

-Dave, K3WQ

David
I see no reference with respect to the ratio between diameters so It
must reflect
solid conductors. If the elements were hollow there could be current
flow within the tube together with skin depth. However, the
communication must be consistent with straight line projectory and
thus the center of the tube would act like a Faraday cage. This is
different to current flow in the center of a solid radiator since
there can be no eddy current within a material of a RF radiator.
Remember, no matter how you read the NEC files equations arrived at
are often approximations since many time portions of equations are
assumed to be negligeable compared to the overall scheme of things and
thus deleted. Do that a few times and it is not known whether the
solutions is a greater or smaller approximation , only a closer
approximation that that created by a planar design. As a U.S.Senator
from Illinois once stated, a dollar here and a millions there and
pretty soon we are talking about real money (Sen Dirksen of Peoria)
Regards
Art