Broadband optimization of a pentamode-layered spherical acoustic waveguide

► A 3-step optimization method is devised to find optimal broadband cloaking parameters. ► Cloaks are comprised of discretely layered pentamode materials. ► The scattering coefficient is minimized over a constrained set of acoustic parameters. ► A fluid loaded sphere is used as an example of the optimization procedure. ► Optimal parameter sets roughly trend those found using transformational acoustics.