Missing Degrees in Mobile Antennas?
 

On 29 Apr 2006 09:37:20 -0700, wrote:

Reference my stub example which contains *NO COIL*. There
is a *short circuit* looking into the stub.

What's your point in making that switch? We were talking about loading
coils, now you are switching to stubs. Why?

compare with:

Please stay on one thing at a time. I have a life besides newsgroups.

Tom,

Enjoy life more by not responding to those issues that are irrelevant
to your enquiry. Look at your question above. It is a sure
invitation to endless rambling - asked twice in the space of three
sentences.

73's
Richard Clark, KB7QHC

Missing Degrees in Mobile Antennas?
 

On 29 Apr 2006 09:47:25 -0700, wrote:

What is it you think
determines current phase shift at each end and current taper?

GROAN....

Missing Degrees in Mobile Antennas?
 

wrote:

I'm going to ask a couple of technical question at the beginning
rather than getting them trimmed and ignored in the body:

1. You seem ready to admit that there is 10 degrees of delay
through a 10 degree long stinger. Yet, if you measured that
delay using standing wave current phase, you would measure
a zero phase shift through the stinger. Why aren't you arguing
that there is no phase shift in the stinger?

2. There is no appreciable standing wave current phase shift from
feedpoint to the tip of the stinger in a 75m mobile bugcatcher
antenna. To be consistent, don't you have to argue that the
75m mobile bugcatcher antenna is zero degrees long?

Cecil Moore wrote:
So you are saying the loading coil is "7's of feet long". Is that
correct?

Compared to a straight wire at 4 MHz, yes, that's what I am
saying. A 75m bugcatcher coil uses about 42 feet of wire.
The delay through that coil is *roughly* equal to about half
that number of feet of straight wire. The reason it is not
equal to 42 feet of straight wire is the flux coupling between
the coils.

Your assertion that nearly 100% of the coils link
nearly 100% of the total flux is unrealistic.

I never said that.

But it would necessarily have to be true for the velocity factor
of the coil to be anywhere near 1.0 and you did say that.

What's your point in making that switch? We were talking about loading
coils, now you are switching to stubs. Why?

THE EFFECT EXISTS WHETHER THE COIL EXISTS OR NOT. Which
indicates it is the nature of standing wave current, not coils,
that you do not understand. The standing wave current phase
is unchanging whether a coil exists or not. ONE CANNOT EVEN
USE STANDING WAVE CURRENT PHASE TO MEASURE THE PHASE SHIFT
THROUGH A WIRE, much less through a coil.

Given that standing wave current phase cannot be used to
measure the delay through a wire, coil, or anything else,
it follows that nobody has provided any valid measurements
for the delay through a coil.

A very similar thing happens with a 75m mobile antenna.
The base loading coil provides tens of degrees of phase
shift.

How do you know that?

The stub involves two different Z0's. The 75m mobile antenna
involves two different Z0's, one for the coil, the other for
the stinger. It's the same principles using the same equations.
The phase shift at the impedance discontinuity depends upon the
ratio of those two Z0's. The higher the ratio, the greater the
phase shift. The ratio of 450 to 50 is obviously 9:1.

A rough estimate of the Z0 of the coil is around 2400 ohms and
a rough estimate of the Z0 of the stinger is around 400 ohms.
That makes the Z0 ratios roughly 6:1.

I'm happy to see you no longer agree with the misplaced notion the
coil replaces missing electrical degrees, but puzzled why you resist
understanding the mechanism that allows the phase shift to change with
coil design.

Speaking of what we both believed two years ago:
I'm happy to see you no longer agree with the misplaced notion that
the coil has equal current magnitudes and phases at each end, but
puzzled why you resist understanding the low velocity factor
associated with helical loading coils. The velocity factor of 75m
bugcatcher loading coils is typically less than 0.1

From the Dr. Corum paper, we have an equation for velocity factor
for coils passing a litmus test. A 75m bugcatcher coil passes that
litmus test with flying colors. The resulting VF is in the ballpark
of 0.04 which is in the ballpark of Reg's VF calculations which is
in the ballpark of Richard Harrison's calculations. Your VF of 1.0
along the length of the coil is the one that is completely out of
the ballpark.

Take your 100uH coil and measure its self-resonant frequency
directly over a large metal ground plane. Keeping everything,
including frequency, the same, cut the coil in half. Add a
stinger to the bottom half of the coil to bring the system back
into resonance at the fixed frequency. We know the delay through
the coil is roughly 45 degrees. We know the stinger is roughly
10 degrees. The impedance discontinuity at the coil to stinger
junction is causing roughly 35 degrees of phase shift. That
tells us that the Z0 ratio of the coil to stinger is about 6:1.

I have been through the above exercise using EZNEC.
--
73, Cecil http://www.qsl.net/w5dxp

Missing Degrees in Mobile Antennas?
 

wrote:
I'm saying that in an antenna of fixed length with a fixed coil
location on a given frequency, I can change ONLY the coil design, still
maintain resonance, and have phase delay of current change
significantly.

So can I - so what? It's the same thing as changing the Z0
of one of the pieces of feedline in my two-Z0 stub example.
No coil is required, indicating once again that your misconception
involves standing waves, not coils.

IMO, you are never going to understand this topic until you
take time out to understand standing waves.

What is it you think
determines current phase shift at each end and current taper?

I explained that at the start of the argument two years ago
and it has been posted on my web page ever since then.

http://www.qsl.net/w5dxp/current.htm

Scroll down to:
"Why the Net Current is not Constant Through a Loading Coil"

My example works in every case.

No it doesn't. Your own current measurements prove that the
current is *NOT* equal at both ends of a coil (and your
phase measurements were invalid). Only one special case toroid
showed the currents at the ends of the coil to be equal. All
the other cases proved that the currents are *NOT* equal.

As Gene Fuller said, the standing wave current phase information
is contained in the magnitude. With a current of 2.0 amps at one
end of the coil and a current of 1.414 amps at the other end of
the coil, it exactly matches the example on my web page. One of
your measurements was very close to 1 amp at one end and 0.7 amps
at the other end. It fits perfectly.
--
73, Cecil http://www.qsl.net/w5dxp

Missing Degrees in Mobile Antennas?
 

Cecil Moore wrote:
1. You seem ready to admit that there is 10 degrees of delay
through a 10 degree long stinger. Yet, if you measured that
delay using standing wave current phase, you would measure
a zero phase shift through the stinger. Why aren't you arguing
that there is no phase shift in the stinger?

Cecil,

Earlier we both agreed the current we measure with a magnetic probe,
which is the most common and widely accepted measurement device, is the
actual current that causes radiation, heating, and the magnetic
induction field. It is the current that heats the element and moves a
thermocouple meter, it is the current that cause I^2R heating, and the
current that moves past one point in the system if we stopped and
counted charges, or if we calculated current based on drift velocity of
charge carriers.

So what current is it you are measuring? Charges cannot flow two
directions at the same time at the same point in a system. There cannot
be drift velocity in two dorections at the same time.

Are you talking about a pulse of current and the return echo?

2. There is no appreciable standing wave current phase shift from
feedpoint to the tip of the stinger in a 75m mobile bugcatcher
antenna. To be consistent, don't you have to argue that the
75m mobile bugcatcher antenna is zero degrees long?

It is however long it is. If it is 7 feet long it is about ten
electrical degrees long on 75 meters, because every foot is about .7
degrees.

Speaking of what we both believed two years ago:
I'm happy to see you no longer agree with the misplaced notion that
the coil has equal current magnitudes and phases at each end,

Maybe two years ago I knew that and published it, so I am happy you
finally see I did.

puzzled why you resist understanding the low velocity factor
associated with helical loading coils. The velocity factor of 75m
bugcatcher loading coils is typically less than 0.1

......and you know that because?

From the Dr. Corum paper, we have an equation for velocity factor
for coils passing a litmus test. A 75m bugcatcher coil passes that
litmus test with flying colors. The resulting VF is in the ballpark
of 0.04 which is in the ballpark of Reg's VF calculations which is
in the ballpark of Richard Harrison's calculations. Your VF of 1.0
along the length of the coil is the one that is completely out of
the ballpark.

I never said 1.0, as a matter of fact the coil I measured had a vF
(when compared to physical length) of about .5

I measured delay through an approximately 100uH coil at:

http://www.w8ji.com/inductor_current_time_delay.htm

You can see the big change at self-resonance near 16 MHz. 3.8 MHz is
not near 16MHz, so the behavior is quite different at the two
frequencies.

Take your 100uH coil and measure its self-resonant frequency
directly over a large metal ground plane. Keeping everything,
including frequency, the same, cut the coil in half.

Sorry, I won't cut the last few pieces of miniductor I have like that
in half.

So what current are you measuring?

73 Tom

Missing Degrees in Mobile Antennas?
 

Cecil Moore wrote:
wrote:
I'm saying that in an antenna of fixed length with a fixed coil
location on a given frequency, I can change ONLY the coil design, still
maintain resonance, and have phase delay of current change
significantly.

So can I - so what? It's the same thing as changing the Z0
of one of the pieces of feedline in my two-Z0 stub example.
No coil is required, indicating once again that your misconception
involves standing waves, not coils.

Now Cecil, get serious.

We all know a stub has distributed capacitance and distributed
inductance. We all know an inductor has the same thing. We can solve
the problem equally well using a network of distributed components as
many others have shown.

IMO, you are never going to understand this topic until you
take time out to understand standing waves.

Well, I could say the same to you about coils and capacitors. :-)

What is it you think
determines current phase shift at each end and current taper?

I explained that at the start of the argument two years ago
and it has been posted on my web page ever since then.

So you don't want to say, or can't say in a few words?

73 Tom

Missing Degrees in Mobile Antennas?
 

wrote:
Earlier we both agreed the current we measure with a magnetic probe,
which is the most common and widely accepted measurement device, is the
actual current that causes radiation, heating, and the magnetic
induction field. It is the current that heats the element and moves a
thermocouple meter, it is the current that cause I^2R heating, and the
current that moves past one point in the system if we stopped and
counted charges, or if we calculated current based on drift velocity of
charge carriers.

It is the current that has the equation: Itot = Io*cos(kx)*cos(wt)
Until you take time out to understand the implications of that
equation, you will *never* understand what I am talking about. That
current cannot be used to measure delay. Yet, that is exactly what
you and W7EL did and, in your ignorance, reported as valid measurements
of delay through a coil. If you had a clue to what you are saying, you
would feel ignorant in the extreme.

So what current is it you are measuring? Charges cannot flow two
directions at the same time at the same point in a system. There cannot
be drift velocity in two dorections at the same time.

Just as two water waves can flow in opposite directions using the
same water molecules, two EM waves can flow in opposite directions
using the same electrons.

Are you talking about a pulse of current and the return echo?

You know that I am talking about the distributed network model,
a superset of the lumped circuit model. Instead of rehashing it
here, please refer to my magazine article at:

http://www.qsl.net/w5dxp/energy.htm

and tell me what it is about that article that you don't understand.

2. There is no appreciable standing wave current phase shift from
feedpoint to the tip of the stinger in a 75m mobile bugcatcher
antenna. To be consistent, don't you have to argue that the
75m mobile bugcatcher antenna is zero degrees long?

It is however long it is.

Exactly the same argument holds for a coil. Think about it. You
cannot deny the validity of standing wave current phase measurements
through a stinger and then turn around and deny that same argument
when it applies to a coil. If W7EL's phase measurements were invalid
for a stinger, then they were equally invalid for a coil.

I never said 1.0, as a matter of fact the coil I measured had a vF
(when compared to physical length) of about .5

Sorry, that's still about 1000% too high, still completely out
of the ballpark. What I suspect is that you measured zero delay
through the coil and reported 3 nS because you knew zero was
obviously wrong.
--
73, Cecil http://www.qsl.net/w5dxp

Missing Degrees in Mobile Antennas?
 

wrote:
So you don't want to say, or can't say in a few words?

I know one of your tactics used to "win" an argument is
to wear the opponent down to a nub where it is not worth
the effort to continue even when he is right and you are
wrong. I'm not going to play your silly game. All the
information is there on my web page at:

http://www.qsl.net/w5dxp/current.htm
--
73, Cecil http://www.qsl.net/w5dxp

Missing Degrees in Mobile Antennas?
 

On 29 Apr 2006 14:17:20 -0700, wrote:

So you don't want to say, or can't say in a few words?

GROAN

Missing Degrees in Mobile Antennas?
 

W8JI wrote:
So what current is it you are measuring? Charges cannot flow two
directions at the same time at the same point in a system. There cannot
be drift velocity in two dorections at the same time.

Cecil Moore wrote:
Just as two water waves can flow in opposite directions using the
same water molecules, two EM waves can flow in opposite directions
using the same electrons.


That's where you are wrong Cecil.

While the effects of energy and reflection of current and voltage can
be considered as a real actionl, current actually can only flow one
direction at one time at one point in one conductor . There is no other
way.

You are confusing a model that is supposed to aid people in solutions
as the "real" thing happening.

Every single thing that can be done with standing waves can be done
with circuit solutions, and we cannot have charges moving two
directions at the same time at any one point in the system.

The radiation from a short antenna is easily tied directly to
ampere-feet, and the amperes that cause that radiation **is** the
current Roy and I measured. The current Roy and I measured is the
current level causing heat.

Be assured that along the short length of the conductor at any fixed
instant of time in one spot, you cannot possible have two potentials or
charge differences causing charges to move two directions at once.

What you are saying is you have something that cannot actually happen
and even if it could it has no effect and cannot be measured, and that
is what is important to you and makes the rest of the world wrong.

No wonder no one can agree with you!

73 Tom