We begin the microwave radio discussion with “the medium through which electrical and magnetic forces act is called “ ether. ” With the theories as to its composition or construction we are not here concerned. It is, however, by virtue of this medium which fills all space that electromagnetic disturbances. . . are made manifest at a distance.
Of the periodic disturbances thus transmitted light and heat are two classes. The periodic disturbance made use of in wireless telegraphy form a third class.”
John Mills, Radio Communication, McGraw – Hill Book Company, 1917
Microwave radio, a form of radio transmission that uses ultrahigh frequencies, developed out of experiments with radar (radio detecting and ranging) during the period preceding World War II. The first primitive systems, used in military applications in the European and Pacific theaters of war, could handle up to 2400 voice conversations over five channels.
Developed by Harold T. Friis and his associates at AT&T Bell Telephone Laboratories, the first public demonstration was conducted between the West Street laboratory and Neshanic, New Jersey, in October 1945. Construction began on the first experimental microwave telephone network in 1947.
Microwave radio systems are point – to – point radio systems operating in the Giga Hertz (GHz) frequency range. The wavelength is in the millimeter range, which is to say that each electromagnetic cycle or waveform is in the range of a millimeter, which gives rise to the term microwave.
(Horak 2007)
 during the period preceding World War II.){kind=link}