Radar and sonar imaging-a tutorial introduction

Aperture synthesis is one of the most important techniques in radar and sonar imaging. Applied to radar and sonar, the techniques of aperture synthesis have interesting similarities and differences. Many of the differences are associated with the much lower velocity of propagation in the sonar case, but also, variations in temperature and salinity of seawater cause reflection and bending of the ray paths, so sonar propagation has similarities with the propagation of HF radio waves in the ionosphere. The purpose of this paper, then, is to provide a tutorial review of synthetic aperture imaging, attempting to highlight the similarities and differences between the radar and sonar cases.