Wide sonar bandwidth with advanced processing enables improved system capabilities in sensors and arrays. However, transmitting and receiving bandwidth greater than one octave remains an emerging technology. Multiple resonances and high coupling materials are now viable options to increase the bandwidth of a device, but there is no study to date of a multiply resonant device that uses high coupling material. A set of guidelines is presented for the design of elements for wideband sonar arrays having bandwidth greater than one octave using multiple resonances, high coupling materials, or some combination.