Ed Cregger wrote:

I have quite a few engineering books on antennas (that I use G), so I
can appreciate the value of good, solid engineering text/sources.

However, the point that the OP was trying to make was that it is likely
that superconductive radiating elements could establish the need for a
serious rethinking of antenna theory. After all, superconductive
radiating elements did not exist before and the math has not been done.
Perhaps, their inclusion, will demand something more than a simple
extrapolation of existing antenna theory. I believe this to be the point
of the OP.
. . .

And I disagree. The assumption of zero loss is implicit or explicit in
nearly all the analyses in your antenna texts and mine. So no new math
or "rethinking of antenna theory" is required to deal with lossless
conductors. It is, in fact, the simplest case and so underlies virtually
all the current theory. What it would do is cause a change in tradeoffs
which would be made by engineers in the design of real antennas.

However, superconductors (at least all known conventional and
high-temperature superconductors) are lossless only at DC.
Superconductor loss increases with frequency and, except at DC, with
temperature. The resistivity of copper decreases quite dramatically with
temperature, so it's not uncommon to find situations at very high
frequencies and very cold temperatures where copper does better than a
superconductor. Even high temperature superconductors have to be cooled
to cryogenic temperatures to do reasonably well at very high
frequencies. But again no new math or "rethinking of antenna theory" is
necessary to deal with them -- the same electromagnetic principles apply
and they can be treated like any other conductors with finite resistivity.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Ed Cregger wrote:

I have quite a few engineering books on antennas (that I use G), so
I can appreciate the value of good, solid engineering text/sources.

However, the point that the OP was trying to make was that it is
likely that superconductive radiating elements could establish the
need for a serious rethinking of antenna theory. After all,
superconductive radiating elements did not exist before and the math
has not been done. Perhaps, their inclusion, will demand something
more than a simple extrapolation of existing antenna theory. I believe
this to be the point of the OP.
. . .

And I disagree. The assumption of zero loss is implicit or explicit in
nearly all the analyses in your antenna texts and mine. So no new math
or "rethinking of antenna theory" is required to deal with lossless
conductors. It is, in fact, the simplest case and so underlies virtually
all the current theory. What it would do is cause a change in tradeoffs
which would be made by engineers in the design of real antennas.

However, superconductors (at least all known conventional and
high-temperature superconductors) are lossless only at DC.
Superconductor loss increases with frequency and, except at DC, with
temperature. The resistivity of copper decreases quite dramatically with
temperature, so it's not uncommon to find situations at very high
frequencies and very cold temperatures where copper does better than a
superconductor. Even high temperature superconductors have to be cooled
to cryogenic temperatures to do reasonably well at very high
frequencies. But again no new math or "rethinking of antenna theory" is
necessary to deal with them -- the same electromagnetic principles apply
and they can be treated like any other conductors with finite resistivity.

Roy Lewallen, W7EL


-------------


All excellent points.

I'm thinking - I'm thinking...G


Ed Cregger

Roy Lewallen wrote:
Ed Cregger wrote:

I have quite a few engineering books on antennas (that I use G), so
I can appreciate the value of good, solid engineering text/sources.

However, the point that the OP was trying to make was that it is
likely that superconductive radiating elements could establish the
need for a serious rethinking of antenna theory. After all,
superconductive radiating elements did not exist before and the math
has not been done. Perhaps, their inclusion, will demand something
more than a simple extrapolation of existing antenna theory. I believe
this to be the point of the OP.
. . .

And I disagree. The assumption of zero loss is implicit or explicit in
nearly all the analyses in your antenna texts and mine. So no new math
or "rethinking of antenna theory" is required to deal with lossless
conductors. It is, in fact, the simplest case and so underlies virtually
all the current theory. What it would do is cause a change in tradeoffs
which would be made by engineers in the design of real antennas.

However, superconductors (at least all known conventional and
high-temperature superconductors) are lossless only at DC.
Superconductor loss increases with frequency and, except at DC, with
temperature. The resistivity of copper decreases quite dramatically with
temperature, so it's not uncommon to find situations at very high
frequencies and very cold temperatures where copper does better than a
superconductor. Even high temperature superconductors have to be cooled
to cryogenic temperatures to do reasonably well at very high
frequencies. But again no new math or "rethinking of antenna theory" is
necessary to deal with them -- the same electromagnetic principles apply
and they can be treated like any other conductors with finite resistivity.

Roy Lewallen, W7EL


-------------


All excellent points.

I'm thinking - I'm thinking...G


Ed Cregger

Richard Clark wrote:
On Wed, 05 Dec 2007 10:36:59 -0500, Ed Cregger
wrote:

However, the point that the OP was trying to make was that it is likely
that superconductive radiating elements could establish the need for a
serious rethinking of antenna theory.

Hi Ed,

This is uni-dimensional thinking.

"A new breakfast cereal could establish the need for a serious
rethinking of sewing machine theory."

There are probably more things possible ("could establish") than time
to consider them - and probably on file pending patent. In that
sense, patent publishing could establish the need for a serious
rethinking of replacing burning oil for heat.

"Could establish" ...this could establish a new form of gaming
entertainment in this group. [and conforms to the usage of
self-referential claims]

73's
Richard Clark, KB7QHC


--------------


So, rather than talk about the subject at hand, you would rather argue
about the technically poor writing style I employed. No thanks. G


Ed, NM2K

On Wed, 05 Dec 2007 16:34:50 -0500, Ed Cregger
wrote:

So, rather than talk about the subject at hand, you would rather argue
about the technically poor writing style I employed. No thanks. G

Hi Ed,

Talking already sputtered to the usual banal offerings so common with
the glazed-eye "what if we could only reach that golden city on the
hill," when I turned to commenting on the only thing left: the quality
of entertainment.

And going further with plasma antennas indeed! I remember plasma
speakers. We've had reports of burning water that would rescue us
from our dependence on Oil, -sigh- if only it didn't take more power
lighting up a bottle of Evian than you got out of it. But even
struggling through this doomed topic finds the cliff crumbling from
beneath its heels and its only hope is that the inventors are making a
living as scabs writing for daytime TV.

73's
Richard Clark, KB7QHC

Ed Cregger wrote:


However, the point that the OP was trying to make was that it is likely
that superconductive radiating elements could establish the need for a
serious rethinking of antenna theory.

Actually, the only reason I mentioned superconductors (and thanks to Roy
for putting me straight on that point!) was to examine a vanishingly
short dipole without worrying about losses. I was not trying to alter
existing antenna theory.

Alan