Transducer cloaking for Kim Benjamin

There is an effort to develop metamaterials for cloaking objects in a way that eliminates backscattering and fills in the shadow zone. The development of this cloaking material for spherical and other shapes would inhibit the acoustic detection of objects, such as mines, torpedoes, UUV's, and, ultimately, submarines by a means which would make them invisible to acoustic waves. It has, however, been pointed out that this form of inactive cloaking could cover a target in a way that shields the target from using its own acoustic sonar means for detecting the source, unless the cloaking could be turned off. We address this issue by presenting an active cloaking transducer system which effectively cloaks the target and yet can also be used as an acoustic sonar system. Equivalent circuits and finite element models are used to demonstrate transducer cloaking. This would have been a good transducer project for Kim Benjamin to implement and I believe he would have enjoyed the challenge and developed one of the best cloaking transducer arrays possible.