Discrete amplitude shading for lobe-suppression in discrete array

Abstract

A discrete transducer array of a plurality of discrete transducer elements, o connected as to achieve a good array directivity pattern with as narrow a beam width as possible for a given side lobe level, or as low a side lobe level as possible for a given beam width, or the most favorable combination of the two. This is to be done with the restriction that there is a discrete array of, say 24, elements that must be shaded discretely, for example by using a series-parallel combination of the elements. A particularly favorable combination using 24 elements comprises: a series combination of the three elements at one end in series with the series combination of the three elements at the other end, each element having a relative voltage amplitude of 1/6; a series combination of the next two elements at each end in series together, each of the four elements having a relative voltage amplitude of 1/4; a series combination of the next three elements at either end, each element having a relative voltage amplitude of 1/3; and eight other adjacent pairs in the central region, each element having a relative voltage amplitude of 1/2. This shading method achieves side lobe levels below -25.7 db with a major lobe half-power beam width 1/4 larger than the unshaded 24-element transducer. This transducer has optimum four-zone shading that incorporates the methods of this invention.

Dependencies are inferred from the claim text.