Development of Four-Element End-Fire Array as Seismo-Acoustic Sonar Source

摘要

Because the inherent dangers of buried mines still possess the ability to deny or severely limit the projection of naval forces ashore, continued research and development of landmine detection capabilities is paramount. One promising method for buried mine detection, still in the early development stages, is the use of Seismo-Acoustic waves for target echo location. The goal of the research described in this thesis was to design and develop a four-element end-fire array to be used as a Seismo-Acoustic SONAR source to preferentially excite Rayleigh waves. A four-element end-fire array, consisting of four vertical-motion inertial mass shakers spaced 25 cm apart (approximately one-quarter wavelength), was deployed on the sand in the near- surf zone of Del Monte Beach. The beam of the array was directed to end-fire by using a delay/pulse generator to individually trigger four function generators. Testing at the beach was conducted and results have shown nice end-fire beam patterns at a radius of 3.5 meters with approximately 15 dB suppression to the rear of the array relative to the forward direction.