tom wrote in
. net:

orfus wrote:
Art Unwin wrote:
I have been reading the groups archives on shield antennas and Faraday
shields and the different auguments regarding how shielding or the
Faraday shield works. Frankly it is a total mess and should be removed
so that hams are not mislead.
Shielding is very simple.
A particle with a electromagnetic field strikes the outside of the
shield.
The magnetic field of same passes thru the shield some might say it is
coupled to the inside of the shield.
The magnetic vector component is out of phase with the electrical
field so it will be just a static particle at rest on the inside but
no inline with the electrical field vector which is now a staic
particle at rest on the outside
We now have a arbitrary boundary as discused by Gauss
For equilibrium all vectors impinging on the boundary must be aligned
such that they cancel.
To accomplish this the inner vector or charge MUST move sideways

THE CHARGE WHEN ACCELERATED CREATES A TIME VARYING CURRENT ALONE
WHILE THE OTHER FIELD VECTORS CANCEL OUT
( I believe that this was the object intended in the cross field
antenna)

As with a applied varying current leaves a xmitter to create
radiation, so must the receiver obtain a time varying current.

Maxwells equations show equations with the electric field, the
magnetic field and a time varying current. When you have a electrical
field or vector of a static particle at rest outside the boundary
opposing the static vector on the inside of the boundary you have
nothing left EXCEPT a time varying current in the closed circuit.
For informative descriptions of how radiation occurs view the QRZ
forum of ( antenna construction and design ) threads (3) on the
double helix
antenna ( see you there)
Somebody some where should re write the above such that a definition
is left for those who follow and remove the garbage which is now in
place
TROLL!

Nope. Local loony.

You, however, are a troll until proven otherwise.

tom
K0TAR


Ok, at the risk of stirring muddy water, I'm curious now, I'm new to this
group, and the subject as there clearly seems to be more to it than I knew. I
also don't know of those archives mentioned so I haven't seen the context.

So in simple terms (hopefully) what is the truth of it? As far as I knew, a
photon at RF with energy but no mass will produce a current that changes over
time in a metal that it hits, though I imagine that as metal has resistance
there must also be a voltage too. I've also heard of the 'skin effect' that
means that at high RF frequencies, current flow tends to stay on the surface,
so clearly the picture isn't as simple as DC and Ohm's law. I also know that
when photons in optical fibres meet boundaries between layers they don't
reflect simply on one side, within one region of specific refractive index,
there's apparently some more complex information exchange that amounts to the
photon crossing the border before returning. Which makes me suspect that
equally exotic action happens when RF photons hit metal sheilds. So what IS
correct? And even if there is more to it, does the aggregate of many photons,
and the wave analysis of their behaviour, reduce to a simple model that makes
the OP correct?

I'm asking this because calls of 'troll' and 'loony' aren't working for me.