SONAR Beacons

Sonar Beacon transducers are an integral part of the Sonar Beacon Systems (SBS) in submarines. In the event of an accident or incident, the SBS is activated as an emergency pinger to precisely locate the submarine by the rescue ships. The SBS transducers developed by STEM Ltd are based on the reliable Tonpilz design and operate at 9 kHz (LF) and 37.5 kHz (HF).

Hydrophones

A thin-walled hollow sphere transducer structure redistributes the stress and effectively amplifies incoming stress like a flextensional transducer, based on the sphere’s radius/thickness (r/t) ratio, to provide large hydrostatic piezoelectric charge coefficients. It delivers an omnidirectional electroacoustic response. STEM Ltd uses two different methods to fabricate spherical omnidirectional transducers operating in a wide frequency range from 20 kHz to 1 MHz.

Pingers

Pinger transducers are mainly used in manned and unmanned underwater vehicles, either as projectors to actively search and locate targets or to provide active ultrasound signals for tracking purposes. Depending on the specific demands of the application, the pingers developed by STEM Ltd can operate in a wide frequency range from 20 kHz to 80 kHz. They can either generate highly directional acoustic signals or provide an in-plane omnidirectional transmitting response.

Tonpilz Arrays

Arrays of transducers are used in applications requiring beam forming or active/passive scanning. Transducers based on the Tonpilz design have been developed by STEM Ltd for projector arrays operating at different frequencies on demand.

Piezocomposites

Bulk piezoelectric ceramics have poor electroacoustic performance due to high acoustic impedance. Applications such as side-scan sonar, active vibration control, and energy harvesting also require flexible piezoelectric transducers. The main solution proposed for these challenges is the piezocomposite design, where piezoelectric fibers or particles are embedded in a passive polymer matrix. STEM Ltd has expertise in the fabrication of 1-3 and 0-3 piezocomposites.