Radio waves vs light waves

"Peter Duniho" wrote in message
...

snip
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.

Oh my, Peter is really having a meltdown over this thread.

"Dennis O'Connor" wrote in message
...
Pete old pal, too much caffeine?

Huh?

Firstly, rf energy does refract as it passes through the near field of a
tuned element/antenna

I never said it didn't.

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)

That's just baloney. It gathers more light because of the larger aperture,
letting in more of the incoming light. It has nothing to do with
wavelengths (though, it is certainly true that, a wavelength simply being
one way to measure linear distance, you certainly can measure the lens
aperture in wavelengths, just as easily as in inches, cm, mm, or whatever).

Light spreads out as it travels. At a certain distance, a certain
percentage of the light from a given source is present across a given area.
The percentage is inversely proportional to the distance from the source of
light, and directly proportional to the size of the area. Increase the
area, or decrease the distance, and you get more light. It's a simple
matter of how much light gathering surface you put in front of the light,
and has nothing to do with the relationship between the area and the
wavelength of the incoming light.

The same thing is true of the reflector dishes used for radio astronomy and
other radio reception. Making them larger allows them to gather more of the
radiation being received. It's as simple as the fact that more of the dish
is "in the way" of the incoming radiation. It's no different than how a
bucket with a one foot opening will catch more rain than a glass with a one
inch opening.

Just because wavelength is a distance and diameter is a distance, that
doesn't mean that every effect caused by a change in diameter is directly
related to the radiation's wavelength. Size matters in other ways too.
Introducing wavelengths simply obfuscates the issue.

Pete

"Peter Duniho" wrote in message
...
"Dennis O'Connor" wrote in message
...
Pete old pal, too much caffeine?

Huh?

Duh?

"Teacherjh" wrote in message
people are uncomfortable with nuclear reactors in space.

Well, uncomfortable with getting them there, actually.

--
Jim Fisher

"Peter Duniho" wrote:

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

Jose - In case you want confirmation, Pete's giving you good
advice here.
Todd Pattist
(Remove DONTSPAMME from address to email reply.)
___
Make a commitment to learn something from every flight.
Share what you learn.

I'm not in favor of the term 'conductor', which implies electron flow, in
this discussion, as the electron is a phenomenon not directly responsible
for the principles of refraction/reflection of light...

Actually, metals do respond to light in several ways.. One is the
photoelectric effect there's your electron flow... And, thin layers of
metals are coated onto glass surfaces to alter it's refraction/reflection
characteristics to light, so metal can both refract and reflect at light
frequencies, depending upon the bulk state, without depending upon electron
flow...

And glass is too nonspecific a term, as various elements/molecules can be
incorporated into basic soda glass to alter it's transparency to EM energy
at various wavelengths ranging from rf to light and beyond...

The point you make about all material/physical response depending on
wavelength is right on... The only difference between the radio signal from
the local rock station and a gamma ray, is wave length...

Enough QED physics here - I'm off the topic...
denny


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)

Peter Duniho wrote:
"Dennis O'Connor" wrote in message
...

Larger is better, however... Look at the dish at Arecibo for example..
http://www.rainforestsafari.com/observe.html


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.


There are indeed refracting antennas. A common type is a dielectric
antenna in the form of a plastic "wedge" shape that protrudes, for
example, from the end of a waveguide. Various vehicular "speed radar"
detectors used antennas like this in years past. Microwave antennas
can also employ solid lenses, made of materials like polystyrene, and
for larger lenses that would be heavy, a matrix of plastic balls
with an overall lens shape serves the same purpose while saving weight.
A convenient material to experiment with for making you own dielectric
antennas is common paraffin wax.

Tom Pappano, PP-ASEL-IA

"Todd Pattist" wrote in message
...
"Peter Duniho" wrote:

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.

Jose - In case you want confirmation, Pete's giving you good
advice here.

Jose has been posting to me for years.

The difference being, Jose doesn't get his apnties in a wad when he learns
something.

I cannot run the train
I cannot ding the bell
But let it jump the goddamned track
And see who catches hell

(Posted prominently above my engineering bench)

Jim



Nomen Nescio ]
shared these priceless pearls of wisdom:

- Face it, nobody likes an engineer.....................until they have a
problem
-that NEEDS to be solved.



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

"Nomen Nescio" ] wrote in message
...
-----BEGIN PGP SIGNED MESSAGE-----

From: "Tarver Engineering"

Jose has been posting to me for years.

The difference being, Jose doesn't get his apnties in a wad when he
learns
something.

There seems to be quite a few "Wads" in this group and, as a rule, they
HATE engineers. As registered PE's, we're the lowest of the lows.

That is the natural reaction to an engineer by a mechanic.

My uncle owned an electrical contracting company in Texas and he hated PEs.

The
"know it alls". I guess we're supposed to forget that we've spent years
banging our heads on books on dif. eq's, physics, electrical circuit
analysis,
thermodynamics, fluid mechanics, gas dynamics, chemistry, mechanics of
materials, and methods of scientific analysis as well as a hundred other
subjects.

They get the most upset when we point out the paradox one of their newsgroup
concensuses.

Then we're supposed to defer to someone who read an article
in "Flying", or worse, "Popular Science".
Face it, nobody likes an engineer.....................until they have a
problem
that NEEDS to be solved.
This should really get me on the "sh*t list" around here.

If FAA had implemented FAA Order 8110.37 (1966) WRT professional engineers a
lot less dead people. FAA has now coppied the NCEES model state law into
their Designee selection process.