Reflections from focused liquid-filled spherical reflectors

Abstract

Experimental measurements are presented for the target strength and directivity patterns of the reflections from stainless steel spherical shells filled with a mixture of carbon tetrachloride and freon (F113) in the frequency range 30–130 kHz. Five spheres were tested having nominal outside diameters of 6, 7, 10, 12, and 18 in. with varying wall thicknesses. Target strength measurements were made separately on echo components arising from reflections from the front and rear surfaces of the sphere; the focused rear-surface reflections showed target strengths up to 21 dB higher than those corresponding to the front surface, controlled by the sphere wall material and thickness, and by the index of refraction of the fluid. Subject Classification: [43]30.30.