Selective filtering of spatio-temporal plane waves using 3D cone filter banks

A 3D cone-shaped pass band is ideally required for the selective filtering of spatio-temporal plane waves on the basis of their directions of arrival. A method is proposed for approximating 3D cone-shaped pass bands using a 3D cone filter bank structure in which the bands consist of band limited 3D beam filters having 3D bandwidths that are approximately proportional to their distance from the origin in the 3D frequency space. The individual 3D beam filters way be realized from a cascade of stable 3D frequency planar filters, each of which corresponds to a passive stable 3D continuous-domain frequency-planar prototype filter.