A phase-locked receiving array for high-frequency communications use

An automatically phased HF receiving array using separate RF amplifiers for each element and IF signal combination is discussed. The type of array considered corrects essentially all phase errors between the distant transmitter and the point where the received signals are combined. This includes errors due to the propagation path, array element motion, near-field obstructions, and instabilities in electronic equipment and RF cables. The array also corrects phase shifts due to changes in angle of arrival, thus giving it the highly desirable property of automatically tracking a desired signal. The effects of interference on array performance and methods for minimizing these effects are discussed. The effect of a single monochromatic interfering signal is discussed in some detail, and results showing regions of acceptable and unacceptable performance in terms of the ratio of desired-to-interfering signal strength and the difference between desired and interfering signal frequencies are presented. A six-element experimental array is described, a technique for measuring patterns is discussed, and measured array patterns are compared with calculated array patterns.