"Bob" wrote in message
...
On Tue, 23 Aug 2005 22:47:28 +0200, "Meindert Sprang"
wrote:
Theorethically yes. In practice, it doesn't matter that much. A shield
works
because it creates loops of current, opposite of that in the inner
conductor
which keeps the field in.

during transmission. in receiving it acts as a ground.

From the cable's point of view, there is no difference between transmission
and reception. Only the power levels are different. The screening principle
works the same.

A practical mesh size on for instance parabolic
antenna's is 1/10 of the wavelength. This will yield a good field
reflection. So on VHF, where the wavelength is about 6 ft, a mesh size of
7
inches would already shield. On many older FM radiostations, "coax" was
was
made by an inner conductor surrounded by a "screen" of many (say 20)
outer
conductors supported by metal rings.

except many electronics systems operate at freqs far above VHF.

Yep. So let's assume the openings in the screen are 1mm. That will still
screen up to 10mm wavelength, aka 30GHz.

Meindert