Sidelobe reduction by nonuniform element spacing

A perturbational procedure for reducing the sidelobe level of discrete linear arrays with uniform amplitude excitation by using nonuniform element spacing is presented. The calculation of the required element spacings is quite simple. The method can reduce the sidelobe level to about
2/N
times the field intensity of the main lobe, where
N
is the total number of elements, without increasing the beamwidth of the main lobe. Several examples are given.