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jawod · December 3rd 06, 09:58 PM posted to rec.radio.amateur.antenna

wrote:
PS,
Think of a simple flashlight with a mirror and a lens.

As a simple analogy, the filament of the light is the driven element
with a mirror behind and a lens in front...a LIGHT Yagi, no?

No diff in P-in/p-out...just all light directed out of the flashlight
into a beam.

John,

You're right about the efficiency, but be careful with the flashlight
analogy. A light yagi might have ~ 200 nanometer long elements.

An 20m band reflector analogous to that in a mini maglight would have
to be 800 miles in diameter.

Thanks for the response, Dan.

I'm not sure a yagi in it's HF form can work at all in the visible
spectrum. I just wanted to treat the yagi notion of a reflector and
director as it occurs within the light spectrum (form isn't important):
directional efficiency is what I was trying to get at, and seems to be
missed by some posters

73,

John