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