Scanning the special issue on radio telescopes

The present issue (vol.82, no.2, 1994) is the third in the Proceedings of the IEEE to be devoted to radio and radar astronomy. The first appeared in January 1958, a significant date because it was 25 years after Karl G. Jansky´s first report of his discovery of Galactic radio noise. The second was 15 years later in September 1973, and was devoted to reporting how the science had progressed. The 15-year timespan had marked a period of rapid advance that had yielded a wealth of discoveries. Now, 21 years later, the field is still dynamic and continues to produce an abundance of findings, due in part to the large number of new observatories. In the present issue, the focus is on the design and performance of the antennas and the instrumentation used in radio astronomy. The issue concentrates on already existing and operational telescopes. Perhaps yet a future issue is merited, one devoted to those new telescopes that are still on the drawing boards