Studies on coaxial circular array for underwater transducer applications

Abstract

This thesis presents analytical methods to study important aspects of a coaxial circular array for wideband underwater transducer application. It begins with detailed theoretical study of a coaxial circular array of three turns and an analysis for the farfield patterns. The array performance is studied for five different operating wavelengths. The appearance of narrow beams confirms the usefulness of the array for high-resolution bathymetry. Studies on mutual interaction effects between the elements of the coaxial array from the next stage of investigation during which a hybrid formulation is developed to provide a computationally efficient method of calculating impedance. Different sidelobe suppression techniques including uniform and nonuniform excitations are also computed. Remaining portion of thesis is devoted to in-water aspects in terms of probability density functions, echo wave-form structures and relative echo energy densities for rippled bottoms of sand, clay and silt. It has been found that beam patterns are less distorted for multiplicative arrays than for the additive types. Present work also includes comprehensive accounts of the historical development of array antennas/transducer systems in the introductory chapter