Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
I hate to see Cecil and others criticizing Tom's (W8JI) measurements,

I know you hate to see your and Tom's errors exposed.
But you have already confessed that even EZNEC says
that standing-wave current phase is almost unchanging
all up and down a 1/2WL dipole.

Which means that your "measurement" using standing-
wave current to measure phase shift through a loading
coil is something that you are well aware is invalid -
yet you have asserted that you are standing by that same
(invalid) "measurement". What is your agenda?

It
means making careful measurements with good equipment and methodology
which give different results. I'm sure we'll never see this from Cecil.

On the contrary, I reported a ~25 nS delay through my
75m bugcatcher loading coil when it was loaded with
a 3600 ohm load. Although this is an estimate from
observing current waveforms, it is close enough to
prove that is could never be the 3 nS reported by W8JI.
W8JI's delay "measurement" is off by a magnitude. Your
phase "measurements" are completely meaningless.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Tom Donaly wrote:
So, since the phase shift has to be 90 degrees, the antenna
should always resonate at the same frequencies a quarter wave
stub of the same electrical length would resonate at, right?

Not sure what you mean by this statement. 90 degrees
is 90 degrees. A mobile antenna physically shorter
than 1/4WL is still close to 90 degrees long at
resonance. (It is not exactly 90 degrees because of
the well-known end effects.)

In order for the reflected wave to be in phase with
the forward wave at the feedpoint (purely resistive
feedpoint impedance), the reflected wave must traverse
180 *electrical degrees* during its round trip. That
fact inticates that the antenna is electrically 90
degrees long.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Tom Donaly wrote:
And, if the total electrical length isn't 90 degrees, you
add a few degrees to the loading coil to make it come out right.
Very ingenious.

Adding or subtracting loading-coil degrees is what
happens while one is tuning a screwdriver antenna.
At resonance, the screwdriver is electrically very
close to 90 degrees in length.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Fry wrote:
Do you believe that a 75m mobile antenna system using an artificially
resonant (as in bugcatcher-loaded), electrically short whip produces the
same elevation pattern and groundwave field strength at 1 km as an unloaded
1/4-wave vertical monopole for 75m with the same applied power using a good,
buried radial r-f ground (say, 2 ohms or less)?

No, the radiation pattern depends upon the *physical*
length. The feedpoint impedance depends upon the
*electrical* length. (I haven't said anything about
the radiation pattern in my postings.) Unless the
antenna is "full-sized", the physical length and
electrical length are different.

There is a free lossless phase shift between the top
of a loading coil and the stinger. There's obviously
zero radiation from that dimensionless point. That 40
electrical degrees of antenna is not physically there
so it cannot radiate.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Tom Donaly wrote:
And, if the total electrical length isn't 90 degrees, you
add a few degrees to the loading coil to make it come out right.
Very ingenious.

Adding or subtracting loading-coil degrees is what
happens while one is tuning a screwdriver antenna.
At resonance, the screwdriver is electrically very
close to 90 degrees in length.

Suuurrrre it is. You've got 90 degrees on the brain, Cecil.
Next, you'll be talking about 90 degree equilibrium.
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

Tom Donaly wrote:
Cecil Moore wrote:
Adding or subtracting loading-coil degrees is what
happens while one is tuning a screwdriver antenna.
At resonance, the screwdriver is electrically very
close to 90 degrees in length.

Suuurrrre it is. You've got 90 degrees on the brain, Cecil.
Next, you'll be talking about 90 degree equilibrium.

The technical content of your posting is noted, Tom.
I gave you the opening to nail my hide to the wall.
Is this the best technical argument that you have?

Please describe how 45 electrical degrees of transmission
line can be brought to 1/4WL resonance without help
from discrete components.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:

...
The same could have been said of Galileo. Do you
suggest that technical absurdities go unchallenged?

Cecil:

I have remained silent, I cannot continue to do so, I am attempting to
prove/disprove the areas you investigate--your posts are appreciated
here--if you are wrong? So what, it gives an old man something to do
.... ;-)

Anyway, the time is better spent; And, better than listening to someone
who went through a mental disorder focused on Shakespeare--those leaning
towards the gay lifestyle bore me ... ROFLOL

Regards,
JS

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:

Cecil:

All that is to be known, is known; there is nothing worth looking to. I
am nothing if I question the status quo--1984 I love you!!!

My gawd man, do you think me stupid??? ROFLOL

Regards,
JS

Loading Coils; was : Vincent antenna
 

On Nov 29, 9:11 am, Jim Kelley wrote:
....
Over the range of a few octaves, propagation delay on the other hand
does not vary to any significant extent as a function of frequency.
Ostensibly, it should be equal to sqrt(LC) series L, shunt C.


Actually, Jim, I do expect it to have considerable frequency
dependence. I think you can find info about this in books that
address the design of travelling-wave tubes.

But...one must be very careful about describing exactly the experiment
or the conditions around a particular scenario. That's why I don't
have much interest in getting involved in this "discussion": it could
well be that much of the difference among all the claims and counter-
claims could be trivially resolved through better communication.

Cheers,
Tom

Loading Coils; was : Vincent antenna
 

Jim Lux wrote:

...
It wasn't km and miles, it was pounds and newtons AND
the error was that Lockheed Martin supplied the thrust data in pounds,
unlike the contractual requirement to supply it in Newtons (which is
what we at JPL have used for decades). The error wasn't caught because
the absolute magnitude of the force is very small, so the differences
from predict to observation were on the order of the measurement
uncertainty. (We're talking measuring the velocity to mm/sec and range
to mm, when its at Mars.)
I'd venture that anyone would find measuring distances to 1 part in 1E12
challenging...
...

Damn, well someone told me, at work, told me it was a kilo/miles problem
.... however, the difference you state resulted in the same, apparent,
outcome--so sue me roflol

I must say, predictable!

Regards,
JS