Richard Clark wrote in message
...
On Wed, 13 Oct 2004 04:31:54 GMT, "Tom Donaly"
wrote:
I suspect Chuck's phrase is little more than an attempt to
seem technically erudite without, alas, conveying any information to the
reader. In short, bafflegab if done intentionally, self deceit otherwise.

Hi Tom,

Well considering "virtual bi-directional coaxial phasing/delay line."
in isolation, I find it rather un-remarkable (if this is in fact an
accurate quote). Afterall, each and every aspect is perfectly
achievable by any NEC modeler on the market (even ones with less than
standard GUIs).

Virtual? That is the first approximation of modeling from the outset.

Bi-directional? There is nothing to impede direction in any
interpretation.

Coaxial? This is merely a tedious exercise in construction.

Phasing/delay line? This follows of necessity and application of ANY
design of wire described within ANY modeler.

Indeed Richard,

Anyone who understands antennas,
in my opinion, wouldn't be
demonstrating ignorance in regard to
those mundane terms.

That said, I take exception with your
statement regarding the
bi-directionality of the simulated
coaxial transmission lines in available
NEC(n) engines. Their simulations are
uni-directional - from the input to the
load, but not in reverse.

As we all know, real transmission
lines allow energy to flow in either
direction. In order to model my
design correctly, a modeling program
must be able to simulate a real
coaxial phasing line, which the
available NEC(n) engines do not
readily do.

Please consider the following:

Some years ago - using EZNEC - I
modeled my basic 2 element driver
using a simulated a bi-directional
coaxial phasing line, by placing two
such lines side-by-side - one fed at
the front matching network and
terminated in the rear matching
network, the other fed at the rear
matching network and terminated in
the front matching network. Applying
empirical data to the rear input
(simulating the induced energy), the
ensuing results were consistent in
every way with the empirical model.

While this may or may not be
definitive proof, it does strongly
support my assertion.

Feeding induced energy from a
passive antenna into an active
antenna is common practice in AM
broadcast engineering.

All I've done is to simply apply a
variation of this methodology to
improve the basic Yagi design. No
fairy dust, black magic, or voodoo
is involved, and the laws of physics
remain intact!

In fact, any competent person can
produce similar results using a
NEC(n) engine (or EZNEC), if they
make an effort to understand the
principals involved and can endure
the tedium.

interesting irrelevancy snipped

Barring testimonials, I may be wrong and my ignorance be disclosed by
evidence. Or some may call me stupid but not Ishmael ;-)

73's
Richard Clark, KB7QHC

A description of the simulated
coaxial transmission line is in the
EZNEC manual.

73,
Chuck, WA7RAI