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Mark Cudworth · September 12th 08, 05:59 AM posted to rec.radio.amateur.antenna

wrote:

That is interesting. I thought the PR dish was parabolic. As a
parabola, the reflected waves (or particles if you will) of a
transmitter at focal point can only traverse in one direction, that
is, in a direction parallel to the tangent of a line drawn at the
lowest point of the parabola. If the parabolic reflector is
stationary, how can transmitted waves/particles go in any direction
but straight up in that perpendiculr direction? If you move the focal
point as you say they do, then the antenna does not finction as
parabola anymore and gain should drop drastically, agree? I am afraid
I must be missing something and request your technical advice. Thanks.

The Arecibo radio telescope has a spherical reflector, not parabolic.
This is mentioned on the official web page:

http://www.naic.edu/public/the_telescope.htm

It also gives details on how the telescope operates.

--
Mark Cudworth