On Aug 30, 5:25 pm, Sjouke Burry
wrote:
Tam/WB2TT wrote:
"Dave Platt" wrote in message
...
What is the highest radio frequency used for astronomy? Is it 3,438
GHz?

According to the link below, it is 3,438 GHz:

http://books.nap.edu/openbook.php?re...=11719&page=11

Is 3,438 GHz the highest radio frequency used for astronomy?
That's very much a matter of convention. It all depends what you
choose to call "radio frequency" and what you choose to call something
else.

As the article you cite points out, the measurements at 3438 GHz
(3.438 THz) blur the lines between microwave measurements (which many
would call "radio") and far-infrared measurements (which may would not
call "radio frequency").

One source I see gives a frequency of 3.0 THz as the boundary between
"microwave" and "infrared". That boundary point is, I believe,
entirely one of human convention - there's no magical change in the
behavior of the signals as you cross from one side of this frequency
to the other.

If you choose to treat the conventional boundary point of 3.0 THz as
being significant for the purpose of your question, then one would
have to say that the 3,438 GHz measurements you refer to are *not*
"radio frequency" measurements, but rather "far-infrared"
measurements.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

I am curious here. At some point you have to switch from metallic conductors
and antennas to lenses and other optics. Any idea what the highest frequency
RF amplifier works at?

Tam

I have even seen optics and electronics combined in an experimental
Road radar for car control from Philips, radar output was a very small
horn antenna connected to a wave guide, and in front of that they used a
plexyglass condensor lens to make a narrow beam, like you do with light.
Apparently those mm waves liked that plastic lens just fine.

In fact, that would work fine at 10GHz, at 1GHz, and even at 1MHz,
though the amount of material you'd have to use for the lens gets
prohibitive at lower frequencies. It's all engineering tradeoffs. I
know that "geodesic" lenses are used in some radar systems; the idea
is that you have the signal travel a longer path (through a curved
waveguide structure) in the center of the antenna/feed than it does
toward the edges, just as in a convex lens the light in the center of
the beam is slowed for a greater distance (and therefore retarded
more) than the light at the outer edges.

I expect the boundary between "optics" and "electronics" will blur
even more than it is already as both electronics and optical
technologies continue to advance.

Cheers,
Tom

It's "Radium" And His Asking Questions - DOH !
- - - And Cross-Posting to Rec.Radio.Shortwave Again !

Apparently those mm waves liked that plastic lens just fine.

In fact, that would work fine at 10GHz, at 1GHz, and even at 1MHz,
though the amount of material you'd have to use for the lens gets
prohibitive at lower frequencies. It's all engineering tradeoffs. I
know that "geodesic" lenses are used in some radar systems; the idea
is that you have the signal travel a longer path (through a curved
waveguide structure) in the center of the antenna/feed than it does
toward the edges, just as in a convex lens the light in the center of
the beam is slowed for a greater distance (and therefore retarded
more) than the light at the outer edges.

I expect the boundary between "optics" and "electronics" will blur
even more than it is already as both electronics and optical
technologies continue to advance.

Cheers,
Tom

Hi Tom, we've used plastic lensing since at least the late 60's for focusing
mundane 4-12 GHz radio waves. Dielectric refraction was used back then to
extract additional gain from dish antennas by allowing more even
illumination of the dish without illuminating the area around the dish.
Harris radio had a patent on it.

W4ZCB

In article om,
says...
Hi:

What is the highest radio frequency used for astronomy? Is it 3,438
GHz?

According to the link below, it is 3,438 GHz:

http://books.nap.edu/openbook.php?re...=11719&page=11

Is 3,438 GHz the highest radio frequency used for astronomy?


Thanks,

Radium



Actually, it says 3 THz.
3.4GHz is C band, like satellite TV. Ku band sat TV is 12GHz.
There are many off-the-shelf radio instruments available well above this.

On Aug 30, 7:26 pm, "Harold E. Johnson" wrote:
Apparently those mm waves liked that plastic lens just fine.

In fact, that would work fine at 10GHz, at 1GHz, and even at 1MHz,
though the amount of material you'd have to use for the lens gets
prohibitive at lower frequencies. It's all engineering tradeoffs. I
know that "geodesic" lenses are used in some radar systems; the idea
is that you have the signal travel a longer path (through a curved
waveguide structure) in the center of the antenna/feed than it does
toward the edges, just as in a convex lens the light in the center of
the beam is slowed for a greater distance (and therefore retarded
more) than the light at the outer edges.

I expect the boundary between "optics" and "electronics" will blur
even more than it is already as both electronics and optical
technologies continue to advance.

Cheers,
Tom

Hi Tom, we've used plastic lensing since at least the late 60's for focusing
mundane 4-12 GHz radio waves. Dielectric refraction was used back then to
extract additional gain from dish antennas by allowing more even
illumination of the dish without illuminating the area around the dish.
Harris radio had a patent on it.

W4ZCB



Hi Harold,

Yep. The radar stuff I wrote about is from that era. I wouldn't be
at all surprised to see mention of it from well before that; certainly
we knew about the effect that makes dielectric lens action possible
for RF (which is after all just a continuation of the spectrum that
includes visible light) since before we knew how to generate
appreciable energy at microwave frequencies.

Cheers,
Tom

On Aug 31, 8:34 am, John Todd wrote:
In article om,
says...





Hi:

What is the highest radio frequency used for astronomy? Is it 3,438
GHz?

According to the link below, it is 3,438 GHz:

http://books.nap.edu/openbook.php?re...=11719&page=11

Is 3,438 GHz the highest radio frequency used for astronomy?

Thanks,

- - Radium
-
- Actually, it says 3 THz.
- 3.4GHz is C band, like satellite TV. Ku band sat TV is 12GHz.
- There are many off-the-shelf radio instruments
- available well above this.

HELLO - 3,438 GHz or 3.438 THz It Don't Matter.
- - It Ain't Shortwave {High Frequency} Radio - -
.
Please remove Rec.Radio.Shortwave from "Radium's
3,483 GHz Radio Astronomy Posting and Your Replies.
.
Listening to Radio Rebelde right now on 11,655 kHz
{Thats in the 25m Shortwave Band} @ 16:57 UTC
http://www.radiorebelde.com.cu/programacion.htm
Horarios y Frecuencias de Trasmisión de Radio Rebelde
.
Listening to the Beautiful Sounds of Latin Music
and yes it sounds Astronomical to my Ears !
.
Radio Rebelde - Habana Cuba - al Ritmo de la Vida
http://www.radiorebelde.com.cu/
TOH News in Spanish @ 17:00 UTC
.
Redsun RP2100 'portable' AM/FM Shortwave Radio
http://www.radiointel.com/review-redsunrp2100.htm
just using the Whip Antenna S2~S3 with Fair Audio.
.
17:30 UTC out ~ RHF - Twain Harte, CA -USA-
.
.
.. .

On Thu, 30 Aug 2007 17:02:02 -0700, Don Bowey wrote:
"Tam/WB2TT" wrote:
...
I am curious here. At some point you have to switch from metallic conductors
and antennas to lenses and other optics. Any idea what the highest frequency
RF amplifier works at?

It's all subject to state-of-the-art. 50 years ago 300 MHz. was complex to
work with and 10 GHz. was considered way out there. Today 300 MHz is about
as simple as DC and 10 GHz. is fairly straightforward to work with.

I imagine that in another 50 years or less, Integrated hybrid circuits for 3
THz. will be on the shelf items for experimenters to play with.

Whenever they discover neutronium, they can make ångstrom-sized
klystrons. ;-)

Cheers!
Rich

On Thu, 30 Aug 2007 17:16:59 -0700, Dave Platt wrote:
Tam/WB2TT wrote:

I am curious here. At some point you have to switch from metallic conductors
and antennas to lenses and other optics. Any idea what the highest frequency
RF amplifier works at?

Dunno about an RF amplifier per se.

I do know that there have been some very interesting experiments with
nanotechnology, over the past couple of years, in which tiny carbon
nanotubes have been used as optical-frequency antennas.

http://www.nanowerk.com/spotlight/spotid=1442.php has a brief writeup
on one such.

So, is anybody making solar panels with them yet?

Thanks,
Rich

On Fri, 31 Aug 2007 02:25:14 +0200, Sjouke Burry wrote:
Tam/WB2TT wrote:

I am curious here. At some point you have to switch from metallic conductors
and antennas to lenses and other optics. Any idea what the highest frequency
RF amplifier works at?

I have even seen optics and electronics combined in an experimental
Road radar for car control from Philips, radar output was a very small
horn antenna connected to a wave guide, and in front of that they used a
plexyglass condensor lens to make a narrow beam, like you do with light.
Apparently those mm waves liked that plastic lens just fine.

Now that you mention it, I saw something on the same principle once, but
it was half a ping-pong ball filled with paraffin. :-)

Cheers!
Rich

On Aug 30, 3:08 pm, "Mike Kaliski" wrote:
"Radium" wrote in message

ps.com...



Hi:

What is the highest radio frequency used for astronomy? Is it 3,438
GHz?

According to the link below, it is 3,438 GHz:

http://books.nap.edu/openbook.php?re...=11719&page=11

Is 3,438 GHz the highest radio frequency used for astronomy?

Thanks,

Radium

Radium

As the article suggests, higher frequencies are considered as being in the
infra red wavelengths of light, so 3,438 GHz can be considered to be at the
upper limits of radio frequency astronomy.

Visible light, ultra violet light, x-rays and gamma rays are all
electromagnetic waves at higher frequencies and are also used for astronomy
observations and experiments. Satellites are generally used to observe in
the ultra violet, x-ray and gamma ray spectrums as these wave lengths are
largely absorbed by the earth's atmosphere.

Remember, there are no strict cut off frequencies where one type of
electromagnetic wave becomes another type. Radio merges into infra red which
merges into visible light, ultra violet, x-rays and so on. Any limits are
purely arbitary ones applied by humans in order to categorise the way in
which electromagnetic waves of a certain frequency can be expected to
behave.

Look at a colour palette. It is easy to pick out the primary colours.
Everyone who isn't colour blind can pick out red, blue, green, yellow etc.
But where do you draw the line to decide where red becomes green, blue or
yellow? The colours slowly merge from one to another just as the
characteristics of radio waves change as frequency increases.

Mike G0ULI

Sorry, I meant to ask whether 3,438 GHz is the highest radio frequency
used to receive audio signals from outer space. I should have made my
question more specific. Radio-astronomers study sounds from the sun as
well as visual data.

I wonder if a space station with a 3,438 GHz AM receiver could pick up
any extremely-distant audio signals between 20 to 20,000 Hz [from
magnetars, gamma-ray-bursts, supernovae and other high-energy but
cosmic objects] after demodulating the 3,438 GHz AM carrier wave.