Magnetostrictive

Early WW2 losses prompted rapid research in the field, pursuing both improvements in magnetostrictive transducer parameters and Rochelle salt reliability.

In 1940, the US sonars typically consisted of a magnetostrictive transducer and an array of nickel tubes connected to a 1-foot-diameter steel plate attached back to back to a Rochelle salt crystal in a spherical housing.

The piezoelectric Rochelle salt crystal had better parameters, but the magnetostrictive unit was much more reliable.

The required dimensions were too big for ADP crystals, so in the early 1950s magnetostrictive and barium titanate piezoelectric systems were developed, but these had problems achieving uniform impedance characteristics and the beam pattern suffered.

The SQS-23 sonar first used magnetostrictive nickel transducers, but these weighed several tons and nickel was expensive and considered a critical material; piezoelectric transducers were therefore substituted.

UIT devices rely on magnetostrictive transducers.