SIGNALS BACKSCATTERED BY A ROTATING SLEND ER BODY

The echoes backscattered in the far field by a rigid prolate spheroid at low and medium frequencies are computed and commented. The so-calle d slender-body aproximation is applied to express the pressure backsca ttered by the body when insonified by a harmonic plane wave. The impul se response is then calculated by Fast Fourier Transform for different angles of incidence. The computed echoes exhibit two main peaks, one narrow and one spread out, corresponding respectively to the reflected echo and to the diffracted waves that encircle the body once (''creep ing waves''). The time of arrival of the specular echo corresponds to that provided by Geometrical Optics. An explanation, resulting from th e analysis of the computed echos, is proposed for the times of arrival of the diffracted waves at oblique incidence. However, a theoretical study is required to check the validity of that explanation.