Date: Tue, 23 Jan 2001 10:43:44 -0500
From: "boffin1" <boffin1@compuserve.com>
Subject: LF: Re: vector potential
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Dear Peter,   In response to your responses:

>Without knowing more details of the experiment I can't comment. However,
the effect of magnetic fields
> on electron beams is well known - the fact that you can view this screen
illustrates the effect of this phenomena.

This is amusing. !   I am a very poor one-finger typist and I occasionally
miss a key.  I miss-hit the key for 'p' in the word  'deprived' in this
paragraph.  It appears as 'derived'  which has almost the opposite meaning
and you probably interpreted it accordingly!. 
There is NO magnetic field outside an infinitely long solenoid  and
neglible magnetic field outside a reasonably long thin solenoid such as
that used in the mobile antennas that look  like fishing rods with a spiral
winding along their length but which are very reasonable radiators.  In the
case that you cite of the electron beam in a magnetic field  there is
indeed a magnetic field, so I regret that the example that you cite is  not
relevant.
Incidentally, in the same paragraph, the name of Bohm's co-author should
have been Aharanov - another slip of mine.  

>And with good reason. In our search for the Holy Grail of efficient
>electrically small antennas we do consider many strange devices - some
>invoking Maxwells equations to prove viability. However, the ability to
>radiate or receive efficiently, particularly on LF, sorts out the wheat
from the chaff.

I agree, that is why I am interested in any small antennas that have
reduced ground losses.

> Good for obtaining funding for 'Son of Star Wars'.
>Anyone in the UK, other than Roger, engaged on this line of enquiry?

This does you no credit, Peter!

>Carron's patent 0043591 for his toroid antenna runs to 67 pages! and has
>been in the public domain for some time.(date of filing 13/7/1981)
>It quotes the relationship of vector and scalar potential to electric and
>magnetic fields and the permeability of free space but does not use these
>units in describing the action of his toroid antennas.

You appear to have confused N.J. Carron with Jim Corum!    I will try to
post you a copy of Carron's paper.

>.......Now, has anyone come up with an instrument for measuring Vector
Potential?

With tongue in cheek I must say:  ' Yes, the  S meter!'

>This implies that if Vector Potential cannot be measured then it must be a
>mathematical go-between to simplify calculations.

That is not a logical conclusion.

>While in the rarefied atmosphere of Electromagnetic Theory it appears that
>we  have Electric Vector Potential, Magnetic Vector Potential, and
Electric
>Scalar potential. There may be a Magnetic Scalar Potential but I haven't
>seen one yet.

This is simply a matter of historical usage, a better term might be
'electromagnetic vector potential'  -  to avoid confusion with the vector
potentials used in fluid mechanics.

 I have just turned up a quote from Robert Feynman:  ".... the effects
depend only on how much the field A changes from point to point and
therefore on the derivativesof A and not on A itself.  Nevertheless the
vector A  (together with the scalar potential that goes with it) appears to
give the most direct descriptionof the physics.   This becomes more and
more apparent the more deeply we go into quantum theory.  In the general
theory of quantum electrodynamics, one takes the vector and scalar
potentials as the fundamental quantities in a set of equations that replace
the  Maxwell equations: E and B are slowly disappearing from the modern
expression of physical laws: they are being replaced by A and phi. "

 The fundamental laws of the Universe do not change with size.  Whether one
is dealing with photons in the gamma ray spectrum or in  the radio
spectrum, where a photon at 73 kHz is about 4  km long,  one is dealing
with the same fundamental phenomena and  the same fundamental laws are
obeyed.   My only personal comment on Feynman's statement is that I believe
that we will find that the scalar potential, phi, which is fundamentally
associated with electrons and other charged particles, will be shown to be
the trapped vector potential coherently spinning round within each particle
and therefore appearing as though it is a scalar potential emanating from a
point charge.

 73,  Roger.
             

>the chaff.
And with good reason. In our search for the Holy Grail of efficient
electrically small antennas we do consider many strange devices - some
invoking Maxwells equations to prove viability. However, the ability to
radiate or receive efficiently, particularly on LF, sorts out the wheat
from
the chaff.