Novel acoustic arrays and array pattern synthesis methods
| dc.contributor.author | Wu, Lixue | |
| dc.contributor.supervisor | Zielinski, Adam | |
| dc.date.accessioned | 2018-07-04T22:11:51Z | |
| dc.date.available | 2018-07-04T22:11:51Z | |
| dc.date.copyright | 1992 | en_US |
| dc.date.issued | 2018-07-04 | |
| dc.degree.department | Department of Electrical and Computer Engineering | |
| dc.degree.level | Doctor of Philosophy Ph.D. | en_US |
| dc.description.abstract | Directional acoustic beams are used in diverse sonar systems. For efficient transmission of a sonar signal, the sound energy is projected in a narrow beam . For reduced interference in reception, the sound signal is received from a narrow spatial sector. Typically, such beams have associated sidelobes which adversely affect sonar performance. The goal of this thesis is to propose several novel acoustic arrays which are capable of generating desired search-light-type and fan-type beams with greatly reduced sidelobes. These novel acoustic arrays have fewer elements than conventional arrays of similar performance. The design of such novel arrays is inherently more difficult, however, since it involves nonlinear optimization. Such an optimization is normally computationally intensive and may not be globally convergent. This difficulty has been overcome by newly developed concepts and associated array pattern synthesis methods. A new concept called the equivalent linear array is introduced; a design method based on this concept benefits from existing design techniques developed for linear arrays. The equivalent linear array concept is further developed to lead to a new and effective method for array radiation pattern synthesis. A second new concept called the scale-invariance radiation pattern is introduced, and the subsequent relation between two novel arrays is discovered. Using this concept an angle mapping approach is developed which transforms a radiation pattern generated by a circular ring array to that of an elliptic ring array. This approach takes advantage of methodologies developed for the design of circular ring arrays. A third concept, constraint directions, is introduced; a subsequent new iterative method for array pattern synthesis is developed to meet the need in compact receiving/transmitting array design. With the help of these new concepts, the proposed synthesis methods avoid the use of nonlinear optimization techniques and merely require simple matrix operations. The methods can be applied to the problems of synthesizing radiation patterns of arrays with arbitrary sidelobe envelopes, with nonisotropic elements, and with nonuniform spacing between elements. The usefulness of the developed methodologies is demonstrated in various design examples. The methods developed provide powerfuI tools not only to design novel acoustic arrays but also to design antenna arrays. | en_US |
| dc.description.scholarlevel | Graduate | en_US |
| dc.identifier.uri | http://hdl.handle.net/1828/9590 | |
| dc.language | English | eng |
| dc.language.iso | en | en_US |
| dc.rights | Available to the World Wide Web | en_US |
| dc.subject | Acoustic surface waves | en_US |
| dc.subject | Sound-waves | en_US |
| dc.subject | Signal processing | en_US |
| dc.title | Novel acoustic arrays and array pattern synthesis methods | en_US |
| dc.type | Thesis | en_US |