  A microwave ultra-broadband polarization-independent metamaterial absorber is
demonstrated. It is composed of a periodic array of metal-dielectric
multilayered quadrangular frustum pyramids. These pyramids possess resonant
absorption modes at multi-frequencies, of which the overlapping leads to the
total absorption of the incident wave over an ultra-wide spectral band. The
experimental absorption at normal incidence is above 90% in the frequency range
of 7.8-14.7GHz, and the absorption is kept large when the incident angle is
smaller than 60 degrees. The experimental results agree well with the numerical
simulation.
