Radio waves vs light waves

Although light is not conducted like RF, light behaves very much like RF in
a wave guide.


In a wave guide appropriate to light frequency, or to radio frequency?

Jose

--
(for Email, make the obvious changes in my address)

"Teacherjh" wrote in message
...

Although light is not conducted like RF, light behaves very much like RF
in
a wave guide.


In a wave guide appropriate to light frequency, or to radio frequency?

The size of waveguide is frequency dependant, but the EM characteristics of
light require only a difference of scale. Propigation is still a factor for
materials inside a waveguide though. So as to say, insulator materials may
act differenty to light than RF.

The size of waveguide is frequency dependant...

Then what, new, are you saying? Light is just like RF, just a different F,
therefore a different scale to see the effects. They have already made
antennas that emit light - they are very small, but they work the way radio
antennas work. I'd be surprised if a suitably scaled wave guide (of an
appropriate material) did NOT work with visible light.

I'm also not sure what you mean by:

Although light is not conducted like RF

Jose


--
(for Email, make the obvious changes in my address)

"Teacherjh" wrote in message
...


Metal is not a conductor of light.

Glass is not a conductor of RF.

Pete old pal, too much caffeine?
Firstly, rf energy does refract as it passes through the near field of a
tuned element/antenna... If it did not, no radio antenna could work - just
think, no MTV, what a shame...
A good place to look for this without a lot of calculus is in Les Moxon's,
G6XN, "HF Antennas For All Locations" published by the RSGB... Review the
discussion of Super Gain Antennas for a two element array consisting of a
driven half wave dipole element and a closely coupled parasitic dipole
director... The incoming wave front interacts with the director as it passes
over it, and is bent/refracted, focusing it on the driven element raising
the gain of the antenna in exactly the same manner as a telescopic lens...
John Kraus,W8JK, also has good discussions on this in his tome - Antenna
Engineering Handbook - ...

And you are correct that Arecibo dish is mainly a reflector - which,
interestingly, is simply a special case of refraction - but I was using it
to make the point about gathering power increasing as the diameter of the
antenna in wavelengths, increases - and it is one antenna most non technical
folks are familiar with......

Have a look at Feinman's discussion on the relationship between % of
reflected waves and % of refracted waves as light passes through glass with
two plane parallel surfaces where the distance between the two surfaces is
varied in fractions of a wavelength.. Fascinating... Reflection/refraction
are two sides of the same coin...

And I don't know what to think about your last statement... But let me
point out that the faster lens 'gathers more light' because it has a larger
diameter in wavelengths, compared to the slower lens (assuming same focal
length for both)

cheers ... denny

"Peter Duniho" Radio antennae such as that one use reflection, not
refraction, to focus
radio waves. In fact, I'm not aware of a single refractor radio antenna.

Larger optical lenses are "faster" (i.e. lower f- number) because they
gather more light. It has nothing to do with wavelengths.

Pete

Now you are getting technical... I will be forced to reorient your wave
guide mode discharge if you keep it up...
denny
"Teacherjh" wrote in message
...

radar technicians have accidently had eye damage from looking into a
working
antenna...


or even looking away from... as proximity is the only important factor,
not
orientation.

Jose


--
(for Email, make the obvious changes in my address)

Metal is not a conductor of light.
Glass is not a conductor of RF.


Nothing fundamental here. Glass is not a conductor of UV either. And
distinguish RF radiation (wide light) from RF electric signals (electrons
vibrating quickly, but not as fast as they would need to to transmit LF)

Wavelength dependence. It's what's for dinner.

Jose


--
(for Email, make the obvious changes in my address)

"Teacherjh" wrote in message
...

Metal is not a conductor of light.
Glass is not a conductor of RF.


Nothing fundamental here.

In fact, from an EM standpoint, that is the answer to the original poster's
question.

An iron nail will "focus" RF.

On Wed, 18 Feb 2004 at 22:16:27 in message
%uRYb.353608$na.522124@attbi_s04, Jay Honeck
wrote:

I've never heard of anyone frying their retinas by looking at a radio
transmitter, but this begs the question: Can the lens in your eye focus
radio waves?

No, Firstly the transparency of materials to EM radiation varies with
frequency. Secondly the wavelength of the transmissions is very large
compared to the lens in your eye. A 3GHz transmission has a wavelength
of 10cm.Red light, the longest wavelength of visible light has a
wavelength of about 1 micron (! millionth of a metre).

E&OE
--
David CL Francis

"Tarver Engineering" wrote in message
news
In fact, from an EM standpoint, that is the answer to the original
poster's
question.

An iron nail will "focus" RF.

I don't think Jay has iron nails for lenses in his eyes.

However, it wouldn't surprise me to find you have iron nails in your eyes.
It sure would explain a lot.

Jose: I'm not sure if you are just having fun with Tarver, or if you think
he's actually someone seriously worth engaging. If it's the latter,
however, I recommend you Google on his posts before you invest a lot of time
with him.

Pete