Multi-beam side-scan sonar

Conventional single beam side-scan sonars with beams at about 1o are not well suited for the detection and identification of very small objects TS < -25 dB - e.g. minelike objects. Sonars of very high angular resolution at 0.1o - 0.2o operate in the nearfield and the speed of the sonar's transducer towing has to be reduced significantly. The paper presents a design approach to a multi-beam side-scan sonar where the above mentioned drawbacks have been removed. The sonar has several narrow parallel (not conical) beams simultaneously formed using the method of beam shaping in the nearfield. Two methods of beam shaping in the nearfield are presented. Thanks to them sonars of various quality and cost can be designed. Selected beam patterns for the two methods of beam forming in the nearfield are presented and compared.