Effect of random shading, phasing errors, and elements failure on beampattern and directivity of a linear and planar array

Abstract

The effects of random shading, phasing errors, time quantization and elements failure on the beampattern and directivity of a linear (31 elements) and planar (405 elements) array at 6 kHz are investigated. The results indicate that the effect of shading errors on the mainbeam is minimal, however, it effects the “far off” sidelobe critically. The elements positional uncertainty and time quantization effect the beampattern and directivity dramatically compared to the effects of shading errors. In case of planar array, the effects of these phase errors are pronounced near broadside and endfire. With time quantization of 20 μs (about 4 times the Nyquist rate) and shading error of 5% of ideal condition, the sidelobe level increases up to 10 dB which depends on the steering direction of the beam. The combined effects of shading and phasing errors on directivity is about 3 dB. The elements failure (6%) increases the sidelobe level about 10 dB for a linear array, whereas it has minimal effect on planar array.