Performance of phased array antennas under error conditions

The author outlines a statistical formulation of the average directivity and sidelobe levels for antennas of general or triangular element grid in terms of the standard deviations of amplitude and phase errors in element modules and the percentage of random failures thereof. Statistical average sidelobe levels are also displayed as a family of curves for routine engineering use. The theoretical formulation was tested to ascertain its validity in view of the assumptions invoked in its derivation. It was verified by direct numerical calculations or averaging from radiation patterns of an antenna similar to one that was planned for a space-based radar with various known amounts of errors. The averaging process used is based on a concept of graded resolution in UV space which provides better accuracy than other methods and should be considered for possible applications in the design calculation of large antennas of all types. The analysis showed that, for well-designed large phased-array antennas, the far-out sidelobe level is sensitive to errors in element excitation and failures of element modules.<
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