Re: SETI


Dr. H. Paul Shuch (n6tx@setileague.org)
Thu, 24 Jun 1999 17:38:16 -0400


At 11:45 AM 6/24/99 -0400, Matthew G Cheung wrote: >I meant putting the loop into the dish. >The idea was that the dish would collect the waves and focus it to the >loop which I thought might be able to be plugged directly into an LNA. >how big should the loop be for best reception at a given >>frequency? Loop antennas are generally about one wavelength in circumference at the operating frequency. However, the radiation pattern of a single loop is a linearly polarized torrus, much like that of a dipole. It would significantly over-illuminate a dish, causing significant degradation in antenna noise temperature due to excessive sidelobes. Better by far to use a short helix backed by a reflector, or a cylindrical waveguide feedhorn (coffee tin). -------------------------------- H. Paul Shuch, Ph.D., CFII, FBIS Executive Director, The SETI League, Inc. 433 Liberty Street, PO Box 555 Little Ferry NJ 07643 USA voice (201) 641-1770; fax (201) 641-1771 n6tx@setileague.org www.setileague.org Project Argus station FN11LH "We Know We're Not Alone!"



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