Planned major improvements to the Arecibo telescope

The author describes a proposed upgrading that is intended to increase the sensitivity of the Arecibo radiotelescope by a factor of three to 10 for radioastronomy purposes, depending on zenith angle and frequency. The upgrading will extend the useful short wavelength limit from 12.6 to 3.75 cm, provide continuous frequency coverage between 300 MHz and 8 GHz, and give extra shielding from interference. It will increase the sensitivity by a factor of six to 40 for S-band radar astronomy. In atmospheric radar studies it will provide at least 20 dB of additional protection from ground clutter and interference, and will greatly improve the capability of the instrument as an ionospheric plasma diagnostic tool. New methods of antenna design permit the performance of the telescope to be substantially improved at relatively modest cost by the installation of an offset dual-shaped Gregorian reflector feed system.<>