Communication with Quasi Optical Waves

This paper deals with electromagnetic waves of from about 0.001 millimeter to 10 meters in wavelength. These waves are called quasi optical waves because their performance is very similar to the performance of visible light. Due to scattering and absorption in the atmosphere, however, only two relatively small parts of that range can be used for communication, that is, between 5 centimeters and 10 meters and between 0.0008 and 0.002 millimeter. In the first part of the paper the straight-line propagation characteristics of these high frequencies are discussed. The possibility of concentrating their radiation, and the apparent lack of all disturbances, either atmospheric or manmade, is also emphasized. The feasibility of modulating very high frequencies, and their advantages and disadvantages in various applications are pointed out. Different ways of producing these high frequencies and of detecting and of measuring them are discussed. The second part of the paper deals in somewhat greater detail with the design of tube transmitters and receivers in the range of 5 centimeters to 10 meters. In this group of transmitters are tuned-circuit oscillators and electron oscillators of the Barkhausen type. In the group of receivers considered are detector, regenerative, and super-regenerative circuits.