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Old January 31st 04, 05:07 PM
Reg Edwards
 
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Default Transmission Line = Antenna


Take a close-wound wire helix of diameter D metres and having N = 500 turns
per meter. Wire diameter approx 2mm.

All formulae available from Terman, Kraus, ARRL, etc., etc.

C = 55.5 / (Ln( 2 * H / D ) - 1) picofarads per meter.

L = Square( N * Pi * D ) / 10 microhenrys per meter.

TransLine impedance, Zo = Sqrt( L / C ) ohms.

Propagation Velocity = 1 / Sqrt( L * C ) metres per second.

Take a length of H =1.5 metres of this helix and use it as a short vertical
antenna above a good ground.

It will resonate as a 1/4-wave vertical at 3.5 MHz.

Zo = 3243 ohms.

Velocity factor = 0.0701

Radiation Resistance = 0.176 ohms.

etc., etc.,

It's so simple you can't believe it. ;o)
----
Reg.



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Old January 31st 04, 05:54 PM
Cecil Moore
 
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Reg Edwards wrote:

Take a close-wound wire helix of diameter D metres and having N = 500 turns
per meter. Wire diameter approx 2mm.

All formulae available from Terman, Kraus, ARRL, etc., etc.

C = 55.5 / (Ln( 2 * H / D ) - 1) picofarads per meter.

L = Square( N * Pi * D ) / 10 microhenrys per meter.

TransLine impedance, Zo = Sqrt( L / C ) ohms.

Propagation Velocity = 1 / Sqrt( L * C ) metres per second.

Take a length of H =1.5 metres of this helix and use it as a short vertical
antenna above a good ground.

It will resonate as a 1/4-wave vertical at 3.5 MHz.

Zo = 3243 ohms.

Velocity factor = 0.0701

Radiation Resistance = 0.176 ohms.

etc., etc.,

It's so simple you can't believe it. ;o)


Thanks Reg, this one is a keeper. If you made the helix long enough to
cause a phase reversal in the current, would the world come to an end?
--
73, Cecil http://www.qsl.net/w5dxp



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Old January 31st 04, 08:03 PM
Reg Edwards
 
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--
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........
"Cecil Moore" wrote in message
...
Reg Edwards wrote:

Take a close-wound wire helix of diameter D metres and having N = 500

turns
per meter. Wire diameter approx 2mm.

All formulae available from Terman, Kraus, ARRL, etc., etc.

C = 55.5 / (Ln( 2 * H / D ) - 1) picofarads per meter.

L = Square( N * Pi * D ) / 10 microhenrys per meter.

TransLine impedance, Zo = Sqrt( L / C ) ohms.

Propagation Velocity = 1 / Sqrt( L * C ) metres per second.

Take a length of H =1.5 metres of this helix and use it as a short

vertical
antenna above a good ground.

It will resonate as a 1/4-wave vertical at 3.5 MHz.

Zo = 3243 ohms.

Velocity factor = 0.0701

Radiation Resistance = 0.176 ohms.

etc., etc.,

It's so simple you can't believe it. ;o)


Thanks Reg, this one is a keeper. If you made the helix long enough to
cause a phase reversal in the current, would the world come to an end?
--
73, Cecil

========================

I forgot to say it will also have a 'cosine' current distribution between
base and top.

The antenna 'end effect' can be accounted for if necessary.

When the helix is not close wound, the increase in velocity factor and the
reduction in Zo can be accounted for.

Axial mode radiation cannot be distinguished from normal mode but this is of
negligible consequence until helix circumference approaches 1/4 wavelength
which it never does in the present context.
----
Reg.


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Old January 31st 04, 08:14 PM
Tdonaly
 
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Reg wrote,
(snip)

It's so simple you can't believe it. ;o)
----
Reg.


You're right.
73,
Tom Donaly, KA6RUH


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Old January 31st 04, 08:21 PM
Tdonaly
 
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Cecil wrote,

Thanks Reg, this one is a keeper. If you made the helix long enough to
cause a phase reversal in the current, would the world come to an end?
--
73, Cecil http://www.qsl.net/w5dxp


It also doesn't mean anything. Those formulas for C and L are just
good hand-waving approximations and nothing else. Nice try, though.
73,
Tom Donaly, KA6RUH




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Old January 31st 04, 08:42 PM
Cecil Moore
 
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Tdonaly wrote:

Cecil wrote,
Thanks Reg, this one is a keeper. If you made the helix long enough to
cause a phase reversal in the current, would the world come to an end?


It also doesn't mean anything.


Tom, please build a two wavelength long helical antenna, measure the
current at various places, and then come back and tell us, with a
straight face, that the current phase never goes from positive to
negative.
--
73, Cecil http://www.qsl.net/w5dxp



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Old January 31st 04, 11:25 PM
Tdonaly
 
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Cecil wrote,

Tdonaly wrote:

Cecil wrote,
Thanks Reg, this one is a keeper. If you made the helix long enough to
cause a phase reversal in the current, would the world come to an end?


It also doesn't mean anything.


Tom, please build a two wavelength long helical antenna, measure the
current at various places, and then come back and tell us, with a
straight face, that the current phase never goes from positive to
negative.
--
73, Cecil http://www.qsl.net/w5dxp


It won't work, Cecil. I quit arguing when you quit understanding.
73,
Tom Donaly, KA6RUH



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Old February 1st 04, 12:01 AM
Cecil Moore
 
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Tdonaly wrote:
It won't work, Cecil. I quit arguing when you quit understanding.


And you would rather leave me ignorant than contribute anything
to my understanding. I certainly understand that. I have an
engineering degree and my IQ, according to MENSA, is in the
upper 1/2 of one percent. That you cannot post anything that
I can understand seems to be your problem, not mine. But don't
feel alone. My Southern Baptist Preacher has the identical
problem. His religion interferes with my understanding. Your
math model religion interferes with my understanding in exactly
the same way. Hint: If your math model doesn't predict reality,
it ain't worth much. The original assertion was that the current
into a coil is identical to the current out of a coil. Never mind
that the current has to travel faster than the speed of light to
make that true. Every measurement has proven that there is a
current taper through the coil. Yet, you maintain the original
assertion. There's something seriously wrong with a mind that
maintains concepts that have been proven wrong by measurements.
--
73, Cecil http://www.qsl.net/w5dxp



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Old February 1st 04, 12:37 AM
Richard Clark
 
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On Sat, 31 Jan 2004 17:01:58 -0600, Cecil Moore
wrote:

And you would rather leave me ignorant than contribute anything
to my understanding.


This reminds me of a time when I challenged our Chief Bosun's mate
with: "You can lead a horse to water, but you can't make him drink."

The Chief always had the last word with logic like yours:
"You hold his head under water and suck on his ass."

73's
Richard Clark, KB7QHC
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Old February 1st 04, 01:14 AM
Cecil Moore
 
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Richard Clark wrote:

wrote:
And you would rather leave me ignorant than contribute anything
to my understanding.


This reminds me of a time when I challenged our Chief Bosun's mate
with: "You can lead a horse to water, but you can't make him drink."


Richard, is one iota of scientific proof too much to ask or should
I accept it on faith like you? When I want hand-waving, I go to church.
I expect more than math-model-based religion out of this newsgroup.
Maybe I expect too much. You guys remind me of the people in one
of the Planet of the Apes movies who worshiped Tha Bomb.
--
73, Cecil http://www.qsl.net/w5dxp



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