On antenna tolerance theory

To predict the loss of gain of antennas due to surface deviations which are not distributed uniformly over the aperture, an extension of Ruze´s theory is presented. It is found that the assumption of uniform error distribution, in general, underestimates the axial gain of an antenna whose surface deviations have regional variations over the aperture. This effect becomes significant only when the surface deviations cannot be considered small as compared to the wavelength. Furthermore, it is found that the assumption of a uniform distribution of error may have a significant effect on the predicted scatter even when surface deviations are not large. Assuming that the deviations from uniform distribution are also random, a correction term to the theory is also presented.