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rickman · November 1st 14, 10:47 PM posted to rec.radio.amateur.antenna

On 11/1/2014 5:31 PM, wrote:
rickman wrote:
On 11/1/2014 1:03 PM, wrote:
gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

An antenna is an antenna.

Deep thoughts...

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

Nope, voltage is applied to an antenna causing currents to be created
which in turn cause an electromagnetic field to be created.

As antennas are made of real materials they have a resistance and the
current through that resistance leads to losses.

I thought there were *real* materials with no resistance. Isn't that
what a superconductor is?

Well, to be pendatic, there are no real materials with zero resistance
that can be used to build antennas.

Why can't you build an antenna with a superconductor?

As all the current existing superconductors require a bunch of supporting
equipment to keep them cold, they can't be used for antennas.

Really? What is the problem? There are super conductors at liquid
nitrogen temperatures and you can have that sitting in a flask on your
desk. Why couldn't that cool an antenna? Once you remove the I*R
losses, you don't even have to worry about the radiated power heating
the N2.

I think you are confusing need with practicality. There is nothing to
stop you from making a superconducting antenna. There just isn't a need
for it unless you live in Gareth's world. Hmmm... wasn't that a movie?
Gareth's World?

If room temperature superconductors are ever invented...

However, those are like a cure for the common cold, practical fusion
power, and peace in the Middle East, all just around the corner for
the past half century or so.

I've never heard anyone say either a cure for the common cold or fusion
was "around" the corner. I've never heard anyone say at all that peace
is expected in the middle east.

I believe there are rather cold temperatures in space. A
superconducting antenna could be used there with *no* supporting
"apparatus".

--

Rick

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