Communication has always been a constant preoccupation with mankind. It is indeed the most potent vehicle of civilization. The extent and speed of communication is a measure of progress. Limited to the pace of a human courier or at the most of a horse for 2000 years, the speed of communication rose to that of electric current with the advent of telegraphy and telephony in the 19th century. Use of radio waves in the early 20th century and, lately, light waves, boosted communication to the speed of light.

   The past five decades witnessed a revolution in communication, thanks to the spectacular advances in electronics and space technology. Space Age dawned with the launch of the first man-made satellite, Sputnik-1, by USSR on October 4, 1957. Both light and radio waves belong to the broad family of electromagnetic radiation. Radio waves of extremely high frequencies known as microwaves can simultaneously handle a huge volume of messages. But their....