On Tue, 18 Dec 2007 17:42:00 -0800, Richard Clark
wrote:

On Tue, 18 Dec 2007 12:53:06 -0800, Richard Clark
wrote:

We can then proceed into where confusion might reside (it not being
found in these antennas): GROUND. Yes, the death embrace of the
original models with GROUND profoundly skews the data.

Hi All,

Well, I find there is more technical content to dissect in at least
one dead horse.

Let's look at the "traveling wave" model and see what it has to offer
in the cold harsh light of reality.

Well first, mea culpa's to the readership in using Cecil's models
(never a good idea as they did not attend the question he introduced
whereas mine did). However, moving on to the nut of my copping a
plea. I had not noticed that Cecil drove his wires into MiniNEC
ground - something I have never done in all my modeling. So, my
"changes," as reported, were faithful, but very much unbalanced the
implicit return path through that MiniNEC ground.

Being the good analyst, I then considered my previous work in an even
colder, harsher light of brutal reality. What I did was to replace
that ground path with a wire symmetrical to the 60 footer and then
raised the assembly an inch.

Right off the bat with its performance: -23.74dB
-42.04dB
What could possibly account for all this loss? The "load?"?
And through a follow-up last time, the same conclusion. The
transmission line apparent load for a 100W constant power consumes
99.25 watts

Instead of tossing the load, let's toss ground and put this corpse in
free space. It's performance: -0.30dB
-42.20dB

I don't know how any math error like this could be used to validate a
model, but the efficiency as an antenna that hugs ground so vigorously
hardly measures up to either a dipole or a rhombic. On the plus side,
confusion certainly offers many vendors an income, and suckers are
born every minute who would love a low noise antenna.
Now it enjoys nearly 20dB less noise than before my mistake.

However, what happened to the currents when we discarded ground? Well,
the pristine constant current of the former model plunges right down
the toilet of expectations (while performance shot through the ceiling
at the same time - one has to wonder what was confusing about this?).
Phase change? That cute 90 degrees formerly nudged and cosseted onto
center stage has now been nailed to the floor with no more total
variation than 2.15 degrees. Hard to imagine how a transmission line
could so thoroughly rape its inventor.
The current is still not constant (the original model must rely on a
poor return path to accomplish this). The phase does vary by 90
degrees.

As modified, the current slope reveals this is no longer a traveling
wave antenna (but it never was anyway). This can be remedied by
shifting the last load (the apparent transmission line load) to 750
Ohms.

This, of course, improves nothing in performance.

Turning to the "standing wave" model, would it be instructive how a
ground free performance might similarly fare?

Right off the bat with its performance: -1.69dB
-21.43dB
it would seem a stretch to find any more efficiency (and shows how
that traveling wave model really sucks). However, without ground for
completeness' sake: -0.28dB
-21.12dB

However, what happened to the currents when we discarded ground? Well,
Not enough to discuss.
roughly the same 2 degree shift we found when the "traveling wave"
model split the sheets with ground, but beyond that, an almost
identical current taper and phase lock-down found with the "traveling
wave" model free of ground (or in comparison to itself close to
ground).


So, is there any substantial difference between the two models once
ground's death grip is released? I will leave that question for
tea-leaf analysis, because engineers would have buried this dead horse
long ago.

Well, after sifting my own tea-leaves (one has to wonder how this
escaped the intrepid author's scrutiny) - no not much difference after
all. Transmission lines are pretty robust when designed correctly.

However, neither bear any resemblance to the original post's mention
of rhombic or dipole antennas; and my models of those clearly discard
Cecil's confusion over his named currents by using conventional
designs of conventional antennas. After all, who ever heard of a
traveling wave transmission line? [This is probably the only point
Cecil could ever hope to argue as he would immediately seize on the
opportunity to force that term into the canon.]

***** Irony meter pegged *****

I would like to point out that the only things changed with these
original models was a switch from 2D to 3D analysis to reveal total
loss; and a switch from the ground offered to free space. I look
forward to Cecil, once again, impeaching his own evidence (and
typically without once mentioning the data).

I am sure I have sunken to new lows

Having beaten Cecil in the game of analysis, even to my own, I must be
pond scum by now.

and once I am exposed for what I
am (an English major), vindication will taste sweeter than wine. (may
as well steal that thunder too)

Imagine, I got to the wine decanter first too! :-)

73's
Richard Clark, KB7QHC