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.

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

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.



--
Jim Pennino

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

rickman wrote:
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.

If one were realy determined to do it, one could build the antenna
in a non-metalic container of some sort and keep the container filled
with LN2.

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?

It is not need versus practicality, it is practicality period.

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.

You must not be very old then...

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

You mean other than the shade screen?

You do understand two big problems with space stuff is how to get rid of
any generated heat and Solar heating?

In any case, why?

I^2R losses only become significant in very small antennas and there is
all the space you could ask for in space to build an antenna.


--
Jim Pennino

On 11/1/2014 7:59 PM, wrote:
rickman wrote:
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.

If one were realy determined to do it, one could build the antenna
in a non-metalic container of some sort and keep the container filled
with LN2.

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?

It is not need versus practicality, it is practicality period.

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.

You must not be very old then...

No, I'm not, I'm much less than a century old.


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

You mean other than the shade screen?

You do understand two big problems with space stuff is how to get rid of
any generated heat and Solar heating?

Is there a lot of solar heating near Jupiter? I didn't realize...



In any case, why?

I^2R losses only become significant in very small antennas and there is
all the space you could ask for in space to build an antenna.

You snipped the part of my post that addressed your questions. It would
be better if you read posts before trimming them.

--

Rick

rickman wrote:
On 11/1/2014 7:59 PM, wrote:
rickman wrote:
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.

If one were realy determined to do it, one could build the antenna
in a non-metalic container of some sort and keep the container filled
with LN2.

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?

It is not need versus practicality, it is practicality period.

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.

You must not be very old then...

No, I'm not, I'm much less than a century old.

And I'm the better part of one and heard all of those many times now.

I forgot to add true artificial intelligence to the list.

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

You mean other than the shade screen?

You do understand two big problems with space stuff is how to get rid of
any generated heat and Solar heating?

Is there a lot of solar heating near Jupiter? I didn't realize...

Not a lot but the point is cooling options in space are limited and
you said nothing about where in space.

In any case, why?

I^2R losses only become significant in very small antennas and there is
all the space you could ask for in space to build an antenna.

You snipped the part of my post that addressed your questions. It would
be better if you read posts before trimming them.

I snipped nothing when I responded.



--
Jim Pennino

On 11/2/2014 1:24 AM, wrote:
rickman wrote:
On 11/1/2014 7:59 PM, wrote:
rickman wrote:
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.

If one were realy determined to do it, one could build the antenna
in a non-metalic container of some sort and keep the container filled
with LN2.

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?

It is not need versus practicality, it is practicality period.

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.

You must not be very old then...

No, I'm not, I'm much less than a century old.

And I'm the better part of one and heard all of those many times now.

I forgot to add true artificial intelligence to the list.

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

You mean other than the shade screen?

You do understand two big problems with space stuff is how to get rid of
any generated heat and Solar heating?

Is there a lot of solar heating near Jupiter? I didn't realize...

Not a lot but the point is cooling options in space are limited and
you said nothing about where in space.

lol. No, cooling in space is very easy. Heat radiates quite well.
That's why they can power the electronics with RTGs so well.


In any case, why?

I^2R losses only become significant in very small antennas and there is
all the space you could ask for in space to build an antenna.

You snipped the part of my post that addressed your questions. It would
be better if you read posts before trimming them.

I snipped nothing when I responded.

You are right, it is all there.

--

Rick

rickman wrote in :

No, cooling in space is very easy. Heat radiates quite well.

True but to get the best of it you have to have high grade energy to radiate.
(High temperatures, short wavelengths). If you could efficiently convert low
grade warmth in large amounts, to a small source of incandescent light, you'd
improve it. I'm not sure if such a process is easy or practical. To be worth
doing, it would have to cost less energy to convert than the difference in
that emitted for the two temperatures. It would probably have to use storage
too, for long slow inputs, short strong bursts of output, which complicates
things.

The problem is that low temperature superconductors are way too cool to start
with, so the supporting equipment would be as awkward as that on Earth, and
likely more so.

On Sat, 01 Nov 2014 18:47:32 -0400, rickman wrote:

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

You don't need to go to outer space to see cryogenic radios in
operation.

Superconducting radio frequency
http://en.wikipedia.org/wiki/Superconducting_radio_frequency

In a past project, I worked with cryogenic duplexers and receiver
front ends for cellular service. My part had nothing to do with the
superconducting components, but I got to watch them perform. Filters
with nearly vertical skirts, sky high filter shape factors, zero loss,
near zero noise figu
http://www.suptech.com/wireless_overview_n.php
http://www.suptech.com/pdf_products/cryogenic_receiver_front_end.pdf
http://www.suptech.com/pdf_products/SuperLink_850_G3AB.pdf
Where cryogenic front ends worked best are in installation without
towers, where the coax cable losses were less, and the cryo unit can
be located in a nearby rooftop shelter. These tend to be located in
urban jungles, where signals are traditionally weak, and handset
density rather high.

At the same time, TMA (tower mounted amp) technology appeared, which
provided many of the benefits of cryogenic receiver front ends, but
without the complexity, power consumption, and cost of the cooling
components:
http://en.wikipedia.org/wiki/Tower_Mounted_Amplifier
https://www.google.com/search?q=tower+mounted+amplifier&tbm=isch
http://www.commscope.com/catalog/wireless/2147486004/product.aspx?id=162&sortExp=Name&nrp=100

Also, note that spacecraft all have some form of temperature control
where the electronics do NOT operate at cryogenic temperatures:
http://en.wikipedia.org/wiki/Spacecraft_thermal_control




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
On Sat, 01 Nov 2014 18:47:32 -0400, rickman wrote:

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

You don't need to go to outer space to see cryogenic radios in
operation.

You can see space a lot better with a cryogenic radio.


--
Jim Pennino

On Sun, 2 Nov 2014 05:30:14 -0000, wrote:

Jeff Liebermann wrote:
On Sat, 01 Nov 2014 18:47:32 -0400, rickman wrote:

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

You don't need to go to outer space to see cryogenic radios in
operation.

You can see space a lot better with a cryogenic radio.

On the ground, cooling the LNB is easy enough but how do you cool the
dish? The LNB is looking at the entire dish, which is sitting there
radiating at ambient temperature. Paint is low emissivity white?

Incidentally, I tried making my own LNB cooling derangement back in
the days of 100K C-band LNB's. Peltier 6 pack beer cooler plumbed
with copper ice maker line and an aquarium pump. The signal would
look great for about 10 minutes, and then slowly fade away. It seems
that cooling also causes water to condense on the "mica" waveguide
window. Add a small heater and fan. When I replaced it with a 25K
LNB, the cooler and fan went away. At least in outer space, there is
no condensation problem.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558