The lengths of the radio waves used in ordinary U. S. broadcasting range between 200 and 547 metres. Short-wave broadcasting uses waves around 50 metres in length. Last week "micro" rays only 18 centimetres (7.09 in.) long carried two-way conversations across the English Channel. International Telephone & Telegraph Laboratories and Le Matériel Télephonique of France made the test. Simple equipment did the work. Sending and receiving devices were practically the same. Each device consisted of a vacuum tube which transformed telephone frequency into the high micro-ray frequency of 1,600,000,000 oscillations a second....
Science: Micro Radio
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