The Naval Research Laboratory (NRL) is currently developing low frequency acoustic projectors for use in shallow water environments. Its thin profile is intended for placement onto autonomous underwater vehicles (AUVs) and unmanned underwater vehicles (UUVs). The projectors are designed with a piston mode resonant frequency below 1 kHz. The transmitting output is then followed by a secondary resonance frequency in the 50 kHz range such that the overall output can be used for broadband operation from 1 kHz to 60 kHz.