Localized wave transmission physics and engineering

Abstract

Exact solutions of the scalar wave equation that describe localized transmission of wave energy will be reviewed briefly. These acoustic solutions can be optimized so that they are localized near the direction of propagation and their original amplitude is recovered out to extremely large distances from their initial location. Pulses with these very desirable localized wave transmission (LWT) characteristics may have a number of potential applications in the areas of directed energy applications, secure communications, and remote sensing. The following will be shown. (1) The underlying physics of the LWT effect is closely connected to the additional degree of freedom obtained by coupling the usually disjoint portions of phase space. Position and frequency spectra at different locations in the aperture are different but are highly correlated so that the effective frequency of the aperture is higher than expected and the resulting pulses from these aperture sources reconsitute the frequency content of the LWT packet, hence its pulse shape, as it propagates. (2) The LWT solutions do not violate any known uncertainty relations and satisfy a generalized full phase-space uncertainty relation. (3) The independently addressible element LWT arrays can be designed to dramatically outperform conventional cw-driven apertures. This includes pulse shape, peak amplitude, and energy fluence. New acoustic experimental data that corroborate these theoretical results will also be presented. [This work was performed by the Lawrence Livermore National Laboratory under the auspices of the U.S. Department of Energy under Contract No. W-7405-ENG-48.]