A robust reflector, possibly without an enclosed back structure. A subreflector support that is stable under wind gusts and thermal changes. Minimum number of parts to assemble. Improved pointing accuracy and pointing stability. Because of the small beamwidths at mm wavelengths, a strong technical effort should be directed at improving pointing and focussing accuracy.
Thermal effects dominate the precision of pointing and focussing.
The study should be aimed at keeping pointing precision and focus stability even when the antennas are in strong sunlight, with part of their structure in the sun, and part in the shadow. The telescope pointing deserves a major engineering effort . It may be desireable, in the late 1990's, to try out one or more prototypes of improved antennas with the IRAM Interferometer on Plateau de Bure before starting a big production run for a next-generation mm interferometer. The prototype antennas might then be re-integrated into the new instrument, when it is built.