The performance of adaptive antennas in HF communications

Measurement results and conclusions are presented on the long-term and short-term characteristics of HF signals received with a specially designed experimental array. On the basis of these results, the improvements obtainable with adaptive HF arrays in different HF services are estimated. With regard to long-term performance, tests carried out in 1978 are discussed; they indicate that considerable improvements may be possible by using open-loop control of HF antennas on a given path. It is pointed out, however, that to achieve these goals, careful study of the path and a mathematical model accurate enough for the purpose will be required. With regard to short-term performance, tests carried out in 1980 are summarized; these indicate the great improvements obtainable with HF receiving arrays adapting in real time.