Antennas for Light wrote:
"Researchers...have invented an antenna that captures visible light in
much the same way that radio antennas capture radio waves..."

The cell that powers my calculator has been doing that, converting wave
motion to electricity, for years. The cell forms a diode so its output
is d-c.

Best regards, Richard Harrison, KB5WZI

Completely different effect.

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR

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"Richard Harrison" mentioned:
The cell that powers my calculator has been doing that,
converting wave motion to electricity, for years. The cell
forms a diode so its output is d-c.

Perhaps you could also take a moment to confirm that you understand the
difference between an antenna and a solar cell. I know that you do - which
makes your posting inexplicable.




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Ever tried working HF on a solar cell?

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR

A Lot Of Crazy Folks wrote:
"Perhaps you could also take a moment to confirm that you understand the
difference between an antenna and a solar cell."

Reciprocity rules antenna action. I`m not sure electricity through a
solar cell will cause it to emit light.

Electricity does not travel through a void. Fields travel through voids.

A radio antenna is a transducer that converts between r-f fields and r-f
electricity.

A solar cell is a transducer that converts between light fields and d-c
electricity.

Radio waves and light waves are EM fields that differ in frequency.

Best regards, Richard Harrison, KB5WZI

On Thu, 23 Sep 2004 10:47:24 -0500, (Richard
Harrison) wrote:

A Lot Of Crazy Folks wrote:
"Perhaps you could also take a moment to confirm that you understand the
difference between an antenna and a solar cell."

Reciprocity rules antenna action. I`m not sure electricity through a
solar cell will cause it to emit light.


Hi Richard,

In support of your veiled supposition, yes a solar cell will emit
light. Of course a Lot Of Crazy Folks will then bluster in outrage
that IR is not light. As Thoreau would posit: "A foolish consistency
is the hobgoblin of little minds." The greater consistency is found
in that a solar cell responds to the 90% of the sun's spectrum that is
unseen.

Pick up any LED (which is visible light, I will leave that
determination to the individual), connect a meter to it, and point the
LED at a light source (which is visible light, I will leave that
determination to the individual), and low a potential will be
developed (typically the commonplace 0.7V, but this varies with LED
color). I have also observed this in common diodes - LEDs merely have
optimized their junction for maximum visual exposure.

There is nothing in this to suggest that efficiency follows reciprocal
use. The hobgoblins would be loath to admit that the light bulb also
serves as a light detector - even if poorly (but superbly for RF Power
level measurement).

73's
Richard Clark, KB7QHC

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"Richard Clark"
Of course a Lot Of Crazy [Dogs]
will then bluster in outrage that
IR is not light.

No I would not - you're totally wrong.

BUT...

I would happily remind you or anyone else to pay attention to the word
VISIBLE, as in visible light, when you, or y'all, clearly neglected to pay
sufficient attention (DARPA and all that IR sub-thread) to the exact
contents of the CNN article and my previous postings (all of which were
perfectly clear).

See the diff ?

Furthermore, you're (intentionally?) ignoring my previous Position
Statement: "I'm as in favour of the fundamental sameness of light to radio
waves as anyone." Given IR's position in the spectrum, you can easily
derive how I feel about its nature.

Your comment (top) was unfair - almost mean.

sniff -- ;-)




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On Thu, 23 Sep 2004 22:40:41 -0300, "Dogs - nothing but dogs !!"
wrote:

No I would not - you're totally wrong.

BUT...

Hi Dogs,

Well that about covers it.

73's
Richard Clark, KB7QHC

And a 1" square solar cell is about 50,000 wavelengths on a side.

Roy Lewallen, W7EL

Richard Harrison wrote:

A Lot Of Crazy Folks wrote:
"Perhaps you could also take a moment to confirm that you understand the
difference between an antenna and a solar cell."

Reciprocity rules antenna action. I`m not sure electricity through a
solar cell will cause it to emit light.

Electricity does not travel through a void. Fields travel through voids.

A radio antenna is a transducer that converts between r-f fields and r-f
electricity.

A solar cell is a transducer that converts between light fields and d-c
electricity.

Radio waves and light waves are EM fields that differ in frequency.

Best regards, Richard Harrison, KB5WZI

Roy, W7EL wrote:
"And a 1" square solar cell is about 50,000 wavelengths on a side."

Yes. The wavelength of light is so short, about 1/50,000 inch according
to Roy, that it is measured in Angstroms. The Angstrom is about 10 to
the minus 10th power meter.

My question is why anyone would want to produce micro, micro antenna
arrays when the LASER produces a narrow, uniform, high-intensity beam
of light of one very pure color (frequency) that can be directed in a
very thin concentrated beam over short and very long distances. Maybe
there isn`t such an efficient receiving device?

LASER (light amplification by stimulated emission of radiation) light
can be so intense that it can vaporize the hardest and most
heat-resistant materials. Can`t a receiving LASER be locked in-step with
external synchronization to provide necessary gain and selectivity?

I wrote: "Electricity does not travel through a void. Fields travel
through a void."

Electrons do travel through voids quite readily. Note the display on a
CRT. They take advantage of the emptyness not to colide with matter so
they can continue their flight. There are also countless electrons
wandering in space between the heavenly bodies, but not so many as to
provide a conductor.

What I meant to imply was that an EM wave does not consist of actual
volts and amps until a conductor intervenes to have the fields generate
the volts and amps on it.

Best regards, Richard Harrison, KB5WZI