Dish reflector
 

Jim Kelley wrote:
Anybody get the feeling that Cecil and Art might be the same guy? :-)

A humorous diversion instead of a technical argument -
usually the sign that one realizes that one is wrong.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Loading coils: was Dish reflector
 

Cecil Moore wrote:

For anyone interested in an in-depth look at the
subject of loading coils, here is an excellent
reference.

http://www.g3ynh.info/zdocs/magnetics/part_1.html

"When modeling and using inductive devices, it is
important to be aware that the concept of lumped
inductance is only strictly applicable at low
frequencies."

"In the high-frequency region, it is no longer possible
to treat the coil as though its reactance is purely
inductive; the reason being that a wave emerging from
the coil is now significantly delayed, and therefore
has a phase which differs from its phase on entry."
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Loading coils: was Dish reflector
 

Cecil Moore wrote:
Tom Donaly wrote:

I'm going to break my reply up into two pieces. First I
will address the actual number of degrees occupied by
a loading coil.

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna.

Sorry Tom, that is a false statement. Please stop misquoting
me. The coil occupies some number of degrees but not nearly
enough to make up for all of the "lost" degrees which are not
lost at all as I have demonstrated in the past and will do so
again here. Following is a *resonant open-circuit 1/4WL stub*
that is electrically 90 degrees long yet it is only physically
38 degrees long.

Z1
---19 deg 450 ohm feedline---+---19 deg 50 ohm feedline---open
-j145

The 450 ohm feedline occupies 19 degrees of the stub. The 50
ohm feedline occupies 19 degrees of the stub. The stub is
physically 38 degrees long total. It needs another 52 degrees
to make it electrically 1/4WL long and resonant. The "lost"
52 degrees is *not lost at all* and occurs abruptly at the
junction point '+'. Call the impedance at that point Z1. The
52 degrees of phase shift occurs between Z1/450 and Z1/50.
Microsmith says that Z1 = -j145.

Z1/450 = -j145/450 = -j0.3222

Z1/50 = -j145/50 = -j2.9

Take a look at the number of degrees between -j0.3222 and
-j2.9 on a Smith Chart. Surprise! There is the "lost" 52
degrees. Those degrees are not lost at all and are just
a fact of physics concerning phase shifts at an impedance
discontinuity.

Now if we multiply the stub impedances by 10, we have
a reasonable facsimile of a resonant base-loaded monopole.

19 deg coil
///////////////-----19 deg ~500 ohm stinger-----open
Z0= ~4500 ohms
VF= ~0.02

The loading coil occupies 19 degrees and the stinger
occupies 19 degrees. There is a 52 degree phase shift
at the coil to stinger junction. There are no "lost"
degrees. 19+52+19 = 90 degrees.

There were (are) two sides to the argument.

1. The coil furnishes the "lost" degrees.
FALSE!
The coil furnishes some number of degrees but not
nearly enough to make up for the phase shift at
the coil/stinger junction.

2. The coil supplies almost zero degrees.
FALSE!
The phase shift at the coil/stinger junction is not
enough to account for the "lost" degrees. The magnitude
of that phase shift is easily calculated on a Smith Chart.

Please skip the ad hominem attacks and use the laws
of physics and mathematics to prove me wrong.
--
73, Cecil, w5dxp.com

I don't have to prove you wrong, Cecil, you have to prove yourself
right since you came up with this novel way of explaining antenna
behavior. A false analogy won't prove you right, in any case. Anyway,
this has all been chewed over before, and you've already used your hick
style argumentative techniques to little avail. It's too bad some
amateurs take you seriously enough to believe this garbage. They'd do
a lot better, and know a lot more if they'd learn the techniques and
mathematics found in innumerable books on the subject.
73,
Tom Donaly, KA6RUH

Dish reflector
 

Cecil Moore wrote:
Jim Kelley wrote:
Anybody get the feeling that Cecil and Art might be the same guy? :-)

A humorous diversion instead of a technical argument -
usually the sign that one realizes that one is wrong.

In this case it's a sign that you are wrong - and humorless. :-)

ac6xg

Loading coils: was Dish reflector
 

Tom Donaly wrote:
I don't have to prove you wrong, Cecil, you have to prove yourself
right since you came up with this novel way of explaining antenna
behavior.

I have offered a proof with which I detect no technical
problems and nobody has offered any valid technical argument
against what I have presented. My argument is not novel
and is based on sound physics as presented by the technical
references I have provided.

What I find difficult to understand is the sandbagging
going on in defense of an old wives' tale.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Dish reflector
 

Jim Kelley wrote:
In this case it's a sign that you are wrong -

Jim, please feel free to offer some valid technical
proof that what I have presented is wrong. Most of
what I have presented is from my college textbook,
"Fields and Waves ...", by Ramo and Whinnery.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Loading coils: was Dish reflector
 

Cecil Moore wrote:

What I find difficult to understand is the sandbagging
going on in defense of an old wives' tale.

Your description of the phenomenon is exactly that. Your claims about
standing wave current are unadulterated bull crap. Your understanding
of wave phenomena is significantly flawed in certain respects. You
refuse to recognize where you have erred, and you fend off criticism by
making ludicrous accusations of other people. With all due respect your
behavior is absolutely pathological, which unfortunately, tend to negate
the value in any valid arguments you might otherwise make.

Although some people do occasionally attempt to correct you where you
have made a mistake (others have given up trying), they are not 'out to
get you'. Try to keep it all real and in perspective, OM.

jk ac6xg

Loading coils: was Dish reflector
 

Jim Kelley wrote:
Your claims about
standing wave current are unadulterated bull crap.

You are certainly free to produce the physics and
mathematics to prove your assertion. Where is it?

I have provided equations and references. Please
tell me exactly which ones you dispute so I can
quote them.

Although some people do occasionally attempt to correct you where you
have made a mistake ...

The only mistakes of which I have been accused
are poor choices of words to which I plead guilty.
Nobody has accused me of invalid equations.

What you are experiencing is the dumbing down of
technical people where the lumped circuit model
and "mashed potatoes" model of energy in a transmission
line has taken over.

The equation for standing waves has been quoted
from "Optics", by Hecht; "... Optics", by Born and
Wolf, "Fields and Waves ...", by Ramo and Whinnery,
"Antennas ...", by Kraus, and "Antenna Theory", by
Balanis.

I strongly suspect you are capable of understanding
those references.

The following two equations are equivalent and are
the equations for pure standing wave current as
exists as the primary current on standing wave
antennas.

I(x,t) = 2(V+/Z0)cos(kx)*cos(wt)

I(x,t) = (V+/Z0)[e^(jwt-kx) - e^(jwt-kx)]

If you cannot look at those equations and see that
the phase is unchanging relative to all points on
the wire, you need to go back to school and
hone your math skills.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Loading coils: was Dish reflector
 

Cecil Moore wrote:
Tom Donaly wrote:

No, it's not a diversion. You're making up things in your head.
The original controversy involved a claim by you that the coil in
a short, mobile antenna made up for the degrees lost in said
shortened antenna.

Sorry Tom, that is a false statement. Please stop misquoting
me.

I have the same recollection as Tom.

The loading coil occupies 19 degrees and the stinger
occupies 19 degrees. There is a 52 degree phase shift
at the coil to stinger junction. There are no "lost"
degrees. 19+52+19 = 90 degrees.

There were (are) two sides to the argument.

1. The coil furnishes the "lost" degrees.
FALSE!
The coil furnishes some number of degrees but not
nearly enough to make up for the phase shift at
the coil/stinger junction.

2. The coil supplies almost zero degrees.
FALSE!
The phase shift at the coil/stinger junction is not
enough to account for the "lost" degrees. The magnitude
of that phase shift is easily calculated on a Smith Chart.

Or, maybe

3. A less than quarter wave antenna is less than 90 degrees long.

ac6xg

TEST
 

TEST