A Subtle Detail of Reflection Coefficients (but important to
 

Since the days of Fresnel (1788-1827), this information has been known. To
admit that ham radio is 300 years behind the times is pretty sad.
--
73, Cecil http://www.qsl.net/w5dxp


O.K., Cecil, I want to make a Fresnel lens antenna for forty meters.
What does it look like, and how do I make one?
73,
Tom Donaly, KA6RUH

Tdonaly wrote:
O.K., Cecil, I want to make a Fresnel lens antenna for forty meters.
What does it look like, and how do I make one?

Dunno, but the Fresnel Equation for the amplitude reflection coefficient,
assuming normal incidence, is the reflected electric field divided by
the incident electric field. Reckon your great, great, great, great,
great, great, great, great grandfather knew that along with Fresnel?
--
73, Cecil http://www.qsl.net/w5dxp



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On Sun, 24 Aug 2003 21:53:33 -0500, W5DXP
wrote:

Tdonaly wrote:
O.K., Cecil, I want to make a Fresnel lens antenna for forty meters.
What does it look like, and how do I make one?

Dunno, but the Fresnel Equation for the amplitude reflection coefficient,
assuming normal incidence, is the reflected electric field divided by
the incident electric field. Reckon your great, great, great, great,
great, great, great, great grandfather knew that along with Fresnel?

Hi Cecil,

Stumbling through optics again without a flashlight?

It would look like a beam. [Gad Tom, that was too easy.]

73's
Richard Clark, KB7QHC

Hi Cecil,

Stumbling through optics again without a flashlight?

It would look like a beam. [Gad Tom, that was too easy.]

73's
Richard Clark, KB7QHC

Not for Cecil.
73,
Tom Donaly, KA6RUH

Tdonaly wrote:


Since the days of Fresnel (1788-1827), this information has been known. To
admit that ham radio is 300 years behind the times is pretty sad.
--
73, Cecil http://www.qsl.net/w5dxp


O.K., Cecil, I want to make a Fresnel lens antenna for forty meters.
What does it look like,

Big.

About 1429 times larger than the one for 10GHz that was published in
'Ham Radio' some years ago. Fresnel optics (either concentric refractive
rings or concentric apertures) works perfectly well at RF wavelengths.

and how do I make one?

First hire a crane, and then...


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek