SETI Fresnel Zone Plate Antennas


Henry Wallace (ultrasonic@worldnet.att.net)
Sun, 25 Jul 1999 22:38:26 -0500


Hello All:

Some of you may recall that I have been
working on a BASIC computer simulation
of the Zone Plate as a possible alternative
to dish antennas.

I am happy to report that the Zone Plate, with
a groundplane reflector placed one-quarter
wavelength below the "bullseye" works very
well, according to this simulation. This version
of the zone plate appears to work as well as
a dish of comparable diameter. It has a -18 dB
first sidelobe.

I have a writeup in MS Word 7.0, which includes
three MS Paintbrush illustrations. This writeup
includes the listing of the BASIC simulation.

I will be happy to email this information to all
interested parties.

Dr. Such was kind enough to post some of
my previous efforts to the League site, and if
the demand still exists, I would like to offer
this "final" simulation for similar treatment.

Now someone needs to BUILD one of these
monsters. The version with the feedhorn
mounted 10 meters above a bullseye consisting
of a center spot plus nine rings has a radius
of almost 7 meters, and a total beamwidth of
only 1.28 degrees between the -3dB points...

Henry Wallace
Ultrasonic Energy Systems: Building near
megahertz high-intensity ultrasonic sources...
Please visit us at:
http://www.ultrasonic-energy.com/
 



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