Design of Chaff and Chaff-Supported Communication Systems

The use of chaff for establishing communications of limited duration between nonadjacent troposcatter stations is investigated. The optimum location for the release of chaff is determined theoretically considering the path geometry, the antenna elevation and directivity, and the weather and atmospheric effects. Amplitude, polarization, and fading characteristics of the signal energy scattered by chaff are calculated and the type and weight of chaff required to provide a given signal-to-noise ratio ( ) is estimated. Experiments which were conducted to check the validity of the theoretical calculation are then described. Finally, a practical scheme for overpassing troposcatter stations and for communications between mobile users which are not in line of sight is considered.