Low frequency signals suffer less attenuation than high frequencies. For this reason, low frequency acoustic transducers are chosen for applications requiring long transmission ranges. These include sonar arrays and communications networks. (Defence Research and Development Canada (DRDC) describes the use of barrel stave transducers for sonar applications.)
Flextensional transducers produce low frequencies from small packages. Sensor Technology Ltd. offers Class I barrel-stave (SX01) and Class III double-barrel stave (SX05) flextensional projectors. Both designs transmit at low frequencies: the SX01 has its first resonance at 1.6 kHz and the SX05 at 1.3 kHz.
Typically sought for their low frequency and high output levels (TVR > 120 dB) barrel stave projectors also provide a wide operating bandwidth. The two models listed here span ~4 octaves.
DRDC provides a good comparison of generic Class I and Class III barrel stave transducer designs.
Flexural diaphragm transducers, also known as bender transducers, offer low frequencies from small packages. They produce among the highest output power of any type of transducer of similar size. In fact, comparing radiated output power to either transducer volume or mass, flexural diaphragm transducers have been shown to outperform barrel stave projectors. (See “Bender transducer design and operation” by John L. Delany)
Free flooded rings demonstrate a unique cavity, or “squirter”, mode under water. The transducer couples with the volume of water it encloses, producing a resonance frequency lower than that displayed in air. See our free flooded ring page for details.
Contact us to find the right low frequency acoustic transducer for your application.