Abstract: A broadly tuned transducer system for pulse echo ranging systems has a rigid plate, to a planar radiating front surface of which is applied at least one layer of acoustic coupling material having a density intermediate between that of the plate and an atmosphere into which the transducer is to be coupled. Three or more driver assemblies spaced apart in a two dimensional array are ridigly secured to a rear surface of the plate, each assembly having a loading block and a piezoelectric element compressed between the block and the plate. The driver assemblies all have the same resonant frequency on axes perpendicular to the plate and are driven in phase; they occupy not less than one-fifth and not more than four-fifths of the area of the rear surface of the plate, which is rigid enough to prevent the excitement of significant flexural oscillations. The arrangement permits the transducer to have a large planar radiating surface while using quite small piezoelectric elements.