Thread: another lie
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Old October 19th 04, 12:16 AM
Chuck
 
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Roy Lewallen wrote in message
...
Chuck wrote:
[... ]


The extended thin wire kernel is invoked automatically when the model is
such that it's needed, according to the criteria given in the NEC
manual.


Which states: "Transmission lines interconnecting
parts of an antenna may be modeled either
explicitly by including the transmission wires in the
thin-wire model, OR implicitly by the method
described in the preceding section for nonradiating
networks." Then goes on to explain the implicit
model, followed by: "The implicit model is limited,
however, in that it neglects interaction between
the transmission line and its environment." (Which
is what's implied for a transmission line in the
EZNEC manual.)

When is the thin-wire model invoked?

What is your criteria for this 'automatic' choice?

Continuing: "This approximation is justified if the
currents in the line are balanced, i.e., in a log
periodic dipole antenna, and in general if the
transmission lies in an electric symmetry plane.
The balance can be upset, however, if the
transmission line is connected to an unbalanced
load or by unsymmetrical interactions. If the
unbalance is significant, the transmission line
can be modeled by including the wires in the
thin-wire model."

In the Raibeam design, the load is unbalanced
due to its "plumbers delight" construction and the
resultant matching networks. From this, one
would naturally assume the interconnecting
phasing line must be included in the thin-wire
model.

How does one determine if this is the case or
not?

Why is the user left unable to make this choice
independently?

And BTW, how does one model a receiving
antenna in EZNEC?

you leave me wondering if,
perhaps, some concepts simply lay
beyond your ability to visualize.


Indeed. I also have trouble with Chi, the healing power of crystals,
astrology, homeopathy, reflexology, phrenology, and water witching.


Does this include action-at-a-distance
as well?

Chuck, WA7RAI

Roy Lewallen, W7EL