The new generation of radio telescopes

A review of the development of the paraboloidal dish is presented. The first computer-aided designed radio telescopes such as the 100-meter telescope in Effelsberg,in the 1960's are virtually free of surface deformations due to gravity through the use of homology design. The next biggest limitation, namely thermally induced deformations had to be considered in the 30-meter telescope located at 2870 m altitude on the Pico Velata near Granada. Further improvement of dish precision was connected with the use of high tensile carbon fiber reinforced tubes as in the 15-meter dishes designed by IRAM). To obtain a real sub-millimeter dish (working down to 350 microns) more improvement is necessary.