On Wed, 12 Apr 2006 23:07:20 -0400, "Yuri Blanarovich"
wrote:

I am really done here
Hope triumphs over experience.

Roy Lewallen wrote:
That this concept
is wrong can and has been shown by theory, modeling, and measurement. I
made and posted measurements on this newsgroup in November 2003 which
demonstrated clearly that the presumption is false.

Mike Coslo wrote:
Okay. It looks like we have at least some measurements that differ. Any
idea why that would be?

Yes, because the physical construction of the coil and the antenna
changes the capacitance from the inductor to the outside world and the
impedance loading the coil. It is the ratio of capaciatnce of the coil
to the outside world to the load impedance presented by the whip above
the coil that causes or allows any phase difference in current or
current level at each end of the coil.

It isn't standing waves, it is missing electrical degrees.

I can take a resonant mobile antenna of basically the same height and
construction, change only the coil while maintaining resonance, and
have difference of current and phase of current change all over the
place.

Try reading:

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

there is a link to actual measurements in that text.


The loading coil isn't making the antenna act like a physically longer
antenna. In the extreme case of a physically short inductor at the
feedpoint, it's simply modifying the feedpoint impedance and has no
effect whatever on the antenna's radiation.

Would the inductor then be best right past the feedpoint? Certainly
having the inductor at the far end, or in the middle seems like a bad
place for it. (not talking about trap antennas)

No. The current in the antenna below the loading coil (or a top hat of
sufficent capacitance)is essentially uniform. This increases radiation
resistance. Increased radiation resistance can increase efficiency.

See:

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

73 Tom

"Richard Clark" wrote in message
...
On Wed, 12 Apr 2006 23:07:20 -0400, "Yuri Blanarovich"
wrote:

I am really done here
Hope triumphs over experience.

yep, "hope" with pictures, measurements and descriptions (no good)
vs. "experience" = it can't be, but, but, but... ("proof")
how does the coil have higher current at the top if it loses radiation
through capacitance to W8JI? "Experienced" silencio!!! There is your sign!

Richard, keep up sticking needles, that really sheds light on the subject

Happy Easter to everyone, even unbelievers!

Yuri da BUm

On Thu, 13 Apr 2006 09:42:35 -0400, "Yuri Blanarovich"
wrote:

Happy Easter to everyone, even unbelievers!

Hi Yuri,

I was at Seder last night. Are you calling me an unbeliever?

73's
Richard Clark, KB7QHC

Yuri Blanarovich wrote:
....
yep, "hope" with pictures, measurements and descriptions (no good)
vs. "experience" = it can't be, but, but, but... ("proof")
how does the coil have higher current at the top if it loses radiation
through capacitance to W8JI? "Experienced" silencio!!! There is your sign!

....

Yuri da BUm

Hi Yuri,

Yesterday I posted in this thread a very simple ideal lumped-circuit
specific example of how it happens. Have a look for that. Consider
the capacitance in that lumped circuit to be part and parcel of the
coil in the distributed case, so you can't in the distributed case
separate its current from the coil current; all you see is the current
going in the "input" terminal (1.3 amps, per Cec's request) and the
current coming out the "output" terminal (2.1 amps) into a load
impedance. If you don't overconstrain the problem (that is, if you
don't specify anything beyond reasonable input and output currents and
load impedance) I can show you a lumped circuit with only series
inductance, series resistance to represent loss if you wish, and shunt
capacitance, that will do the same thing with respect to terminal
currents.

It really is not a stretch at all to get more current coming out than
going in. It WOULD be a stretch to have more power dissipated in the
load than you put in the network, but that's not what's happening, of
course.

Is that all specific enough for you, or would you like to give me a
challenge with a different set of input and output currents and load
impedance (which agrees with what you might actually observe in an
antenna-with-loading-coil situation, and not some ridiculous impossible
set)? I'll even embed the capacitance in the circuit so you won't be
able to say you could measure its current separately from that of the
coil. It's a somewhat pointless exercise, but good mental stimulation,
like working a crossword puzzle, so I'm up for it.

(I trust you didn't really mean that the coil loses radiation
_directly_ to W8JI in your posting quoted above! If every loading coil
in the world did that, poor Tom would be getting pretty warm, I
suppose. In any event, PLEASE UNDERSTAND THIS: the displacement
current from the coil is mostly NOT losing power to the outside world.
Like current in more tangible capacitors, it represents stored energy
that's put into an electric field in part of the cycle, only to be
almost all returned in another part.)

Cheers,
Tom

Tom, W8JI wrote:
"It isn`t standing waves, it is missing electrical degrees."

That could be sarcasm because it certainly could be standing waves.

In a coil the RF signal travels as a surface wave around the turns of
the coil (helix) at about the velocity of light. Hopper`s rule says this
is about one foot in a billionth of a second (one nanosecond).

Self inductance can`t magically induce the signal in one end of a coil
instantaneously into the opposite end of the coil. Here`s why. Current
in the coil induces voltage and current lags the applied voltage by
90-degrees (1/4 of the time required for a complete cyclr). That`s a
delay.

Antenna systems produce a reflection from the open-circuit at the tip of
an antenna. The incident wave reaching the tip reverses its direction
becoming the reflected wave, traveling in the opposite direction from
the incident wave. You likely have seen the interference pattern
produced by incident and reflected waves on a transmission line in a
book. The same pattern starts at the tip of an antenna not terminated in
its Zo.

At certain points on the signal path the voltages in the two waves will
be in phase and will add, while at other points they will be out of
phase and subtract. The points along the path where the two voltages are
in phase are points of maximum voltage and minimum current and are
spaced one-half wavelength apart. The points along the path where the
two voltages are 180-degrees out of phase are points of minimum voltage
and maximum current and are also spaced one-half wavelength apart. The
distance between alternate points is one-quarter wavelength.

Coil, wire, free-space, whever you have an incident wave and its
reflection on a path, you will get this interference pattern on a
conductor. So, a loading coil is going to have variations of voltage and
current caused by an energy reflection with or without coupling to the
rest of the universe.

Best regards, Richard Harrison, KB5WZI

Yuri Blanarovich wrote:
vs. "experience" = it can't be, but, but, but... ("proof")
how does the coil have higher current at the top if it loses radiation
through capacitance to W8JI? "Experienced" silencio!!! There is your sign!
Yuri da BUm

Yuri,

It is so obvious to anyone experienced with antenna tuners how that can
happen I really dodn't think it requires an answer at all.

It is possible to build a "current step up network", or a "current step
down network" with two or more reactances, one in series and one in
shunt.

What it is NOT possible to do is make a coil change current without
that third path to the outside world. Standing waves will not do it,
missing antenna degrees will not do it.

Look at a simple L network when you have time, or more closely an L/C/L
T network. You will find all laws of charge conservation are met. The
current at any junction of one source path into two other branches
always totals zero (current in balances currents out).

The antenna is no different. The loading coil in a normal antenna mode
might have a somewhat large phase shift in current of the coil has
considerable shunt capacitance to the outside world or it might have
almost none. This has NOTHING to do with standing waves causing the
difference, or missing antenna degrees causing the difference.

There isn't anything mystical or magical about any of this. The only
problem is Cecil's theory, Barry's theory, and your idea doesn't fit
all systems, and the models and workings presented by Reg, Roy, Tom,
Ian, Gener, and others does work in **every** situation.

I can make a mobile antenna that is resonant, change nothing but the
coil, and have a mobile antenna that is exactly the same size and still
resonant with different currents and phase of currents at both ends of
the loading coil. I can do this simply by changing the coil's
capacitance to the outside world.

I can prove this.

73 Tom

Richard Clark wrote:

On Thu, 13 Apr 2006 09:42:35 -0400, "Yuri Blanarovich"
wrote:


Happy Easter to everyone, even unbelievers!


Hi Yuri,

I was at Seder last night. Are you calling me an unbeliever?

73's
Richard Clark, KB7QHC

Unfortunately Richard, to many, including some I am acquainted with, you
would be considered much worse than that. Minnesota is not as broad
minded as they like to pretend. Religious hangings weren't that long
ago here.

And, as the grandson of Polish Jews who, for some unknown reason, hid
their ancestry to the point where I was raised Catholic, I am obviously
conflicted!

tom
K0TAR

(Continuing the basenote drift, since the basenote thread is pretty
much a mess anyway...)

So it's not clear to me who might be calling whom an unbeliever. Both
Christians and Jews celebrate seder. Maybe it would be those of some
other faith? It's interesting to me--and sad--that so many whose
religion teaches that God is all-powerful and too great to be known
fully by any person are intolerant of others whose religions teach just
the same thing. The intolerance seems as common between sects of
nominally the same religion as between religions. If you can't ever
fully know your god, who are you to say it's not the same god as the
one someone else worships differently, or as someone else worships as a
set of gods?

Hey, we might as well be discussing religion as loading coils...

Ducking,
Tom


Tom Ring wrote:
Richard Clark wrote:

On Thu, 13 Apr 2006 09:42:35 -0400, "Yuri Blanarovich"
wrote:


Happy Easter to everyone, even unbelievers!


Hi Yuri,

I was at Seder last night. Are you calling me an unbeliever?

73's
Richard Clark, KB7QHC

Unfortunately Richard, to many, including some I am acquainted with, you
would be considered much worse than that. Minnesota is not as broad
minded as they like to pretend. Religious hangings weren't that long
ago here.

And, as the grandson of Polish Jews who, for some unknown reason, hid
their ancestry to the point where I was raised Catholic, I am obviously
conflicted!

tom
K0TAR

Wot's seder?

Can one drink wine to excess?

If so, can I join the club?
----
Reg