Page:Popular Mechanics 1928 01.pdf/3

 

Vol. 49

 

Radio waves so short that, like visible light, they cast shadows behind buildings, or even men, are being employed in experiments that promise to open a new era in wireless, particularly in communication with airplanes. The waves are so short that they bring home the point, which engineers have often tried in vain to emphasize, that radio is only another form of light, and not a brother of sound.

Five-meter waves are being used in the experiments conducted by the General Electric laboratory at Schenectady, and, despite the fact that they are giants compared with light waves, the two act very much the same. The average visible light wave is only about one fifty-thousandth of an inch in length, but, though it would take nearly 10,000,000 of them, placed end to end, to equal one five-meter wave, the radio signals of that length emulate light by traveling in a straight line as well as by being blocked when they meet a hill, a house or any other obstruction.

The radio waves used in ordinary broadcasting rarely cast shadows, because of