# 1/4 Wave Theories - Trash Them!

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From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
Sent:  Wednesday, June 10, 1998 11:47 PM
To:  Tesla List
Subject:  Re: 1/4 Wave Theories - Trash Them!

At 07:27 PM 6/10/98 -0500, you wrote:
>
>----------
>From:  Barton B. Anderson [SMTP:mopar-at-uswest-dot-net]
>Sent:  Tuesday, June 09, 1998 1:34 AM
>To:  Tesla List
>Subject:  Re: 1/4 Wave Theories - Trash Them!
>
>To Terry and all,
>
SNIP>>>>>>>>>>>>>>>>>>>>>
>
>Terry,
>
>When I said above "a net reactance", I was talking about the situation when
XL=XC.
>Because both are opposing and opposite, these reactances cancel. If XL =
24ohms,
>then Xc = 24ohms (at resonance), but, if they are opposing and opposite (of
which we
>know this is true) isn't this net reactance "0"? and all that would remain
is the dc
>resistance of the coil?
>

Ok,  there are a few details there, but you are basically correct.

>I know I must be missing something here, I'm just not sure what and am
hoping you or
>someone can clear me up on this point. This is why I was thinking there
should be no
>phase variation (at resonance). I'm not in anyway trying to prove 1/4wave
theory
>(since I obviously don't know it that well), nor am I playing devils
>just trying to understand what I obviously don't. I think the above
situation is
>what is making me question the phase in this particular current measurement.
>

In an antenna, the phase variation is due to the time it takes the
electromagnetic waves to travel the length of the antenna.  In a 1/4 wave
antenna, the length of the antenna is simply equal to the distance light
travels in 1/4 of a cycle or d=c/(4Fo).  There are ways, such as winding a
coil with distributed inductance and capacitance, to make the distance much
shorter.  It is (was) commonly believed that in Tesla coils the
electromagnetic waves only travel the length of the coil during 1/4 of a
cycle instead of the much greater distance one would normally expect.

>BTW, many many thanks for your replies. I've been contemplating yours and
the rest
>of the lists postings on this topic. There's so much unknown (not measured
anyway)!
>One thing that is certain to me, to validate tests, parallel tests of
measurements
>must be made including different methods of measurements. I hope everyone
capable
>will join in to help confirm, document, and speed up this process.

I totally agree!  I am now designing a special planar antenna to make
voltage and current measurements using the antenna principle I happened upon
a few days ago.  This antenna will have much greater frequency response than
the fiber-optics which is important for output arc measurements.  This
equipment is also much easier for others to reproduce than the fiber optics.
My goal of phase measurements will also be more accurate at very high
bandwidths.  Output arcs appear to be creatures of the nanosecond range
instead of the microsecond range.  Fortunately, initial tests do indicate
that that bandwidth will be high enough (hundreds of megahertz).  The fiber
optics have been indicating that high frequency information is being lost to
a degree.   I hope it works :-))  There are others doing the same type of
work as I which will provide the very important function of testing the
principles in a totally different environment.  I seem to be a bit ahead of
them at the moment! :-)

>
>My very best,
>Bart
>

Best regards,

Terry Fritz

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