A sonar system comprising: - a physical antenna; and - a calculation unit; said physical antenna being deformable and comprising a plurality of acoustic receivers having variable positions relative to each other, said system being equipped with positioning means making it possible to determine, in real time, the instantaneous position of each of the acoustic receivers, and said calculation unit making it possible to reconstruct a sonar image by taking account of instantaneous positions of each acoustic receiver, the system comprising at least one acoustic transmitter inside the physical antenna; the system being characterized in that - the physical antenna is connected to the rear of a towed head, said head being provided with an inertial unit adapted to determine the instantaneous position and orientation of said head and in that the physical antenna is equipped with sensors making it possible to determine a relative instantaneous position of the acoustic transmitter and of each acoustic receiver with respect to the head, the physical antenna being formed of a plurality of sections coupled one after the other by as many ball joints, each ball joint being instrumented, said sensors being angular sensors measuring an instantaneous angular information between two considered sections, and in that - said calculation unit makes it possible to form a synthetic antenna by considering a succession of operation recurrences of the sonar system. - a physical antenna; and - a calculation unit; said physical antenna being deformable and comprising a plurality of acoustic receivers having variable positions relative to each other, said system being equipped with positioning means making it possible to determine, in real time, the instantaneous position of each of the acoustic receivers, and said calculation unit making it possible to reconstruct a sonar image by taking account of instantaneous positions of each acoustic receiver, the system comprising at least one acoustic transmitter inside the physical antenna; the system being characterized in that - the physical antenna is connected to the rear of a towed head, said head being provided with an inertial unit adapted to determine the instantaneous position and orientation of said head and in that the physical antenna is equipped with sensors making it possible to determine a relative instantaneous position of the acoustic transmitter and of each acoustic receiver with respect to the head, the physical antenna being formed of a plurality of sections coupled one after the other by as many ball joints, each ball joint being instrumented, said sensors being angular sensors measuring an instantaneous angular information between two considered sections, and in that - said calculation unit makes it possible to form a synthetic antenna by considering a succession of operation recurrences of the sonar system. - the physical antenna is connected to the rear of a towed head, said head being provided with an inertial unit adapted to determine the instantaneous position and orientation of said head and in that the physical antenna is equipped with sensors making it possible to determine a relative instantaneous position of the acoustic transmitter and of each acoustic receiver with respect to the head, the physical antenna being formed of a plurality of sections coupled one after the other by as many ball joints, each ball joint being instrumented, said sensors being angular sensors measuring an instantaneous angular information between two considered sections, and in that - said calculation unit makes it possible to form a synthetic antenna by considering a succession of operation recurrences of the sonar system.