On Tue, 4 Dec 2007 23:48:31 -0500, "AI4QJ" wrote:

I can see how someone in the 1950's might assume that
current in = current out (kirchoff) ... We know better now

Hi Dan,

This is called the "fallacy of present mindedness."

Kirchoff demands that analysis be done free of network geometries that
are wavelength dependant. This was known long before the 1950s.

And another issue:
current in = current out
is not a Kirchoff law for a component and the currents on its leads
(this is a tempting sophomore lab shortcut that is strictly lumped
circuit stuff - which absolutely demands 0 wavelength). Kirchoff's
first law is for a point, or junction; and, of course, there is no
potential across a point or junction (as there would be for a
component).

Engineers knew this long before 1950, presumably 100+ years before in
1845. The first Telegrapher's equations (125 years ago or more) had
to overcome wavelength restrictions - hence the work of Heaviside
through Maxwell.

This, of course, is a repetition for your sake which has been offered
in years past to the same "debaters" for whom it has had:
1. absolutely no impact to their passion play;
2. been entirely forgotten;
3. been wholly outside of their researching skills (i.e. never having
ever taken a circuits lab course beyond the sophomore first quarter);
4. been a combination of 1, 3, and 4 with the pretense of 2.

With the pretense of 2, we will be visited by this astonishing
revelation of current change through the coil again in the future, as
we have been on successive occasions throughout the past. There will
be new and remarkable papers culled from the net that exhibit math to
prove all cogent points - except to sweep the wavelength restriction
for Kirchoff under the rug again.

Thus was it ever, thus will it be again....

73's
Richard Clark, KB7QHC

AI4QJ wrote:

Roy, I will definitely be going through those archives. However, we have
seen many antennas in which the entire antenna is wound as a spiral with a
relatively large pitch in order to shorten it. In this case, the entire
antenna could also be considered an "inductor". For that matter, even a
straight length of antenna wire could be considered a 1/2 turn "inductor".
Ignoring the latter extreme example for now, could not the common spirally
wound antenna be considered an inductor that "replaces" the entire antenna?
I'm not saying it is a "good" antenna but it could be 90 degrees long and
have the same distribution of standing wave current as a straight antenna.
Also, I wonder if we are arguing semantics over the definition of
"inductor".

Definition is definitely a part of the problem. I don't have so much
trouble with variations of defining an "inductor" as I do with the
concept of "replacing" part of an antenna or measuring an inductor in
"electrical degrees". A straight wire and a coiled wire both have the
property of inductance, but in general a coiled wire will radiate less
than a straight one of the same inductance. The coupling to ground or
the other half of the antenna is also different for straight and coiled
wires. So one doesn't directly "replace" the other. The concept of
"replacement" is overly simplistic and, when extrapolated, can lead to
erroneous conclusions (or in the case of Cecil's and Yuri's theories,
multiple and contradictory conclusions).

Take a look at my 2005 measurements and see if you can do what Cecil and
Yuri failed to do coherently -- use the "replacement" concept and
explain where the missing degrees went.

Roy Lewallen, W7EL

AI4QJ wrote:
... it is plain and simple
"intuitive" once you know that current changes along the electrical "degree
length" in an unloaded antenna, the same should happen in the degree length
loaded coil.

Unfortunately, both sides cannot be right but both sides
are still illustrated as fact in the ARRL Antenna Book.
There's one graphic that shows the drop in amplitude
through a loading coil and another that shows no change.
Apparently, the ARRL doesn't know what happens so they
show both possibilities as technically correct.

Also, as indicated, the pictures do say 1000 words and it also looks like
W8JI ended up agreeing with you after you pointed out the same effect at
"ON4UN's Low Band DXing", 3rd Edition, on page 9-34.

Unfortunately, it is rumored that W8JI has talked ON4UN
into changing that in the latest edition. I emailed ON4UN
about it but got no reply.
--
73, Cecil http://www.w5dxp.com

Richard Clark wrote:
Cecil Moore wrote:
Equipment was a dual-trace 100 MHz O'Scope.

What make, model?

Leader LBO-518
--
73, Cecil http://www.w5dxp.com

Roy Lewallen wrote:
It's unfortunate that your intuition is wrong -- an inductor doesn't
"replace" part of an antenna.

Roy, you will not understand how an inductor replaces part
of an antenna until you perform the simple stub exercise
that I have provided. Assume ideal lossless conditions and
a VF=1.0.

--600 ohm line---+---10 deg 100 ohm line---open

How many degrees of 600 ohm line does it take to result
in a stub that looks like it is 1/4 wavelength, i.e.
electrically 90 degrees long.

Anyone want to take bets on who will perform this simple
exercise and who will refuse to touch it with a ten foot
pole?

If you'd like to learn a lot more about this, and the history of the
discussion, see my posting in this group on April 6, 2006 under the
topic " Current across the antenna loading coil - from scratch". It
includes some references to careful measurements I made more than a year
previous which showed that the simplified view of "replacement" is
flawed.

Note to AI4QJ:
Roy's conclusion was obviously flawed because standing-wave
current was used for his measurement. When I pointed out Roy's
error using EZNEC, he buried his head in the sand by ploinking
me. After all these years, no rational person can believe that
a coil doesn't replace part of a mobile antenna.

However, the side that believes that a coil replaces all of
the missing antenna degrees is also wrong. There is a third
phase shift at the coil to stinger junction that this side
is missing.
--
73, Cecil http://www.w5dxp.com

Roy Lewallen wrote:
The concept of
"replacement" is overly simplistic and, when extrapolated, can lead to
erroneous conclusions (or in the case of Cecil's and Yuri's theories,
multiple and contradictory conclusions).

Roy continues with his Big Lie. There are no contradictions.
Perform the following simple stub example assuming lossless
conditions and VF=1.0.

---600 ohm line---+---10 deg 100 ohm line---open

How many degrees of 600 ohm line does it take to make the
stub electrically 1/4WL (90 deg) long? Why doesn't it take
80 degrees of 600 ohm line? Where are the missing degrees?

Take a look at my 2005 measurements and see if you can do what Cecil and
Yuri failed to do coherently -- use the "replacement" concept and
explain where the missing degrees went.

If you would just look at my simple stub example, you would
understand where those missing degrees are. They are at the
coil to stinger junction and may represent more than half
the degrees in the antenna. The coil represents a good portion
of the rest of the degrees. The stinger is usually about 11
degrees long.

Roy continues to defend his old wives' tale even in the
face of overwhelming evidence to the contrary.
--
73, Cecil http://www.w5dxp.com

Roy Lewallen wrote:
Take a look at my 2005 measurements and see if you can do what Cecil and
Yuri failed to do coherently -- use the "replacement" concept and
explain where the missing degrees went.

I didn't fail to explain them, Roy, you just failed to listen
to reason, ploinked me, and started uttering Big Lies about
me.

In my 75m mobile base-loaded bugcatcher antenna:
1. The coil occupies ~25 degrees of antenna.
2. The impedance discontinuity at the coil to stinger
junction provides a ~44 degree phase shift.
3. The stinger occupies ~11 degrees of antenna.

At resonance the antenna is electrically
25+54+11 = 90 deg long even though it is physically
only ~12 degrees long.

All of the "missing degrees" appear at the impedance
discontinuities but you already know that since I
explained this to you two years ago.
--
73, Cecil http://www.w5dxp.com

Gene Fuller wrote:
Cecil Moore wrote:
http://www.w5dxp.com/travstnd.gif

That graph page is beyond simple amusement; it is hilarious.

I'm glad you find it amusing, Gene. Now please explain
why EZNEC came up with that data based on the EZNEC
files that you are free to download and analyze.

All I did was simulate a coil using the helix feature
in EZNEC. For standing-waves, I left the coil un-
terminated. For traveling-waves, I terminated the
coil in close to its characteristic impedance. The
graphs are the exact data reported by EZNEC so
W7EL can be blamed for the results, not I.
--
73, Cecil http://www.w5dxp.com

Roy Lewallen wrote:


A straight wire and a coiled wire both have the property of inductance,

The rest snipped


(Hand smacking against my forehead) For this dilettante, that simple
statement causes a lot of things to fall into place and make sense.

Thanks much, Roy.

- 73 de Mike N3LI -

Cecil Moore wrote:

If you would just look at my simple stub example, you would
understand where those missing degrees are. They are at the
coil to stinger junction and may represent more than half
the degrees in the antenna. The coil represents a good portion
of the rest of the degrees. The stinger is usually about 11
degrees long.

I don't understand. At the junction between the two?

Does this mean that an extremely short antenna could be built that
consisted of several small coils, and lots of junctions?

typical bad ascii art:

| - top stinger
|
/ - coil and junction
/
|
/ - coil and junction
/
|
/ - coil and junction
/
|
| - bottom of antenna



- 73 de Mike N3LI -