Influence of amplitude errors on beam-steered phased arrays

For the image quality of two-dimensional ultrasound systems, spatial resolution is one of the most important parameters. This resolution is determined by the directivity pattern. In practice, the directivity pattern of phased arrays will be distorted due to errors in critical components. In this study two parameters describing the distribution of amplitude errors over the aperture and the range of amplitude errors are dealt with. With these parameters qualitative predictions of the directivity pattern are possible. To keep the directivity pattern acceptable, error parameters must remain within certain limits. Practical guide-lines to evaluate the beam distortion on the basis of a minimum number of simulations or measurements are given.