RadioBanter - skin depth decay

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skin depth decay

In article ,
Cecil Moore wrote:

Why reflections from the feedpoint if the antenna matches the feedline?

If the antenna is fed with 50 ohm coax, the antenna
does not match the feedline. The Z0 of a #14 wire
30 feet in the air is ~600 ohms. It takes a half-cycle
of sinusoidal RF for the feedpoint impedance to begin
to match the coax Z0, i.e. the feedpoint impedance of
a standing wave dipole is a virtual impedance that
doesn't exist until the first reflections arrive from
the ends of the antenna.

Before Reg died, he had something to say about that.

In the back of "TV and Other Receiving Antennas" by Arnold Bailey is
an interesting section which describes a large number of commonly-used
TV antenna configurations - dipoles made of wire and rod, folded
dipoles with various wire diameters and spacings, bot-tie, simple
Yagi, and so forth.

For each such, Bailey gives two impedance figures - the "surge"
impedance and the feedpoint impedance - which I believe correspond to
the two impedances Cecil is referring to (i.e. before, and after the
standing wave is established).

It's an interesting book... out of print for years, and not (as far as
I know) available electronically.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

skin depth decay

On 20 Nov, 16:02, (Richard Harrison) wrote:
I wrote:

"The impressed current will lag the voltage across a pure inductance by
90 degrees."

Roy wrote:

"For other waveforms (like the ones you`d get connecting batteries or
capacitors) you have to resort to the more general time relationship
L*di/dt.

Roy is correct for connecting batteries or capacitors but Art was
working wih a lengthy antenna, not a lone elementary segment. He also
had no step functions, just a sine wave driving his antenna.

Best regards, Richard Harrison, KB5WZI

Oh Richard, you may deny my antenna but that is what I was alluding
to.
Again it is the LC ratio thatmust be kept for resonance. The
importance of these
are their characteristics as storage containers of energy the release
of which
is determined by their time constant. Both release their energy in
turn to
remove static particles from the surface of the radiator in a similar
way
to a battery at the time of explosion.( Note the battery comment
which
is what you responded to} This is the time varient required for
radiation that the masters disclosed but without pertinent details.
This started
when the Gaussian law of statics was shown by me to equate to the laws
founded by
Maxwell. SO WHAT was the thread that then dominated. But for me it was
not the
marrying of Gauss to Maxwell it was the journey taken in pursuit of
knoweledge
that could only be revealed by walking in the same shoes that Gauss
would have done
if he had not deserted mathematics. The journey shows evidence that
static particles
are at rest on a radiators surface. It also provides evidence that
radiators
with respect to Maxwells teachings are a wavelength long and in
equilibrium when
placed with static particles in a arbitary border. It then points to
the
logic of the time varient mentioned by the masters was NOT the sino
soidal current
provided but instead the explosion type release of energy from the
inherrent
storage containers. True sino soidal current runs around the circuit
but only because a
bypass resister is present with all capacitors. This bypass current is
extremely small
compared to the energy blast from a energy container. By the same
token for
equilibrium to be maintained the LC ratio must be kept to simulate the
action of
a pendulum and its occillations. Now the above is revealed not by the
proof
of the final calculations but from all that is observed during the
required journey.,
From the above it becomes obvious that the condition added by
programmers was not only
a fraud but also incorrect when the condition was added to existing
law
(which is fraudulent. When this inaccurate condition is removed and
Maqxwells
laws adhered to the errors generated by this false addition will
disappear.
From the above it can now be said that a radiator can be any shape or
variety
of elevation as long as it is in equilibrium (ala a wavelength long)
where
it can provide a lossless means of radiation when disregarding
frictional losses
of the circuit. It is also impotant to note that if the inductive
energy level
container is made larger at the same time holding to the LC ratio then
the
time constant required for radiation will increase. So think again
when you wish
to say "So What" since the above will become a lasting acceptance of
science
regardless of the baying crowd of this newsgroup that want to depart
to newer
aproaches that describe the Universe.
Oh, and another side comment, I have a rotatable top band antenna on
the
top of by tower using the nsame principles alluded to above and yes it
is directional and does not require a ground plain to attain
equilibrium.
Have a happy day
Art Unwin ....KB9MZ..XG (uk)

skin depth decay

On 20 Nov, 16:23, (Dave Platt) wrote:
In article ,
Cecil Moore wrote:

Why reflections from the feedpoint if the antenna matches the feedline?

If the antenna is fed with 50 ohm coax, the antenna
does not match the feedline. The Z0 of a #14 wire
30 feet in the air is ~600 ohms. It takes a half-cycle
of sinusoidal RF for the feedpoint impedance to begin
to match the coax Z0, i.e. the feedpoint impedance of
a standing wave dipole is a virtual impedance that
doesn't exist until the first reflections arrive from
the ends of the antenna.

Before Reg died, he had something to say about that.

In the back of "TV and Other Receiving Antennas" by Arnold Bailey is
an interesting section which describes a large number of commonly-used
TV antenna configurations - dipoles made of wire and rod, folded
dipoles with various wire diameters and spacings, bot-tie, simple
Yagi, and so forth.

For each such, Bailey gives two impedance figures - the "surge"
impedance and the feedpoint impedance - which I believe correspond to
the two impedances Cecil is referring to (i.e. before, and after the
standing wave is established).

It's an interesting book... out of print for years, and not (as far as
I know) available electronically.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

How many pages does that book of Bailey's have? How much would it
cost
to put on the internet for all hams to enjoy?

skin depth decay

Art wrote:
"Oh Richard, you may deny my antenna but that is what I was alluding to.

Again it is the LC ratio that must be kept for resonance."

I don`t know enough about Art`s antenna to deny it. I do know that
resonance depends on the reciprocal of the sq. rt. of the product of LC,
not its quotient.

Explosive results from an inductor were introduced by Kettering, I
believe, through interruption of battery current through an inductor to
generate a very high voltage spark to ignite the fuel air mixture within
the cylinder of an internal combustion engine for automobiles. Just as I
doubt the inclusion of a pendulum in Art`s antenna, I also doubt the
presence of an interruptor to discharge either the capacitance or
inductance in the resonant antenna.

If Art`s antenna is novel, useful, and not completely obvious from prior
knowlege, he may profit from it. I wish him all the best.

Best regards, Richard Harrison, KB5WZI

skin depth decay

Art wrote:
"How many pages soes that book of Bailey`s have?"

595 and each one is valuable.

Best regards, Richard Harrison, KB5WZI

skin depth decay

Dave Platt wrote:
In the back of "TV and Other Receiving Antennas" by Arnold Bailey is
an interesting section which describes a large number of commonly-used
TV antenna configurations - dipoles made of wire and rod, folded
dipoles with various wire diameters and spacings, bot-tie, simple
Yagi, and so forth.

Yes, an antenna has a surge impedance just like a transmission
line has a surge impedance which is the characteristic impedance.
A standing wave antenna and a transmission line with standing
waves both exhibit virtual feedpoint impedances that differ
from the characteristic impedances.
--
73, Cecil http://www.w5dxp.com

skin depth decay

Roy Lewallen wrote:
Ok, I give up. I've got a dipole in free space. I connect one end of the
load resistance to one end of the dipole. What do I connect the other
end of the resistor to?

How about a nice terminated rhombic?

If that's too tough, how about just a dipole a quarter wavelength above
ground?

How about an inv-V dipole 0.177 wavelength above ground?
--
73, Cecil http://www.w5dxp.com