I. Introduction
Broadband multichannel problems can be expressed using polynomial matrix representations [1]. Such formulations can be used in a number of areas, including broadband angle of arrival estimation [2], [3], polyphase analysis and synthesis matrices for filter banks [4], and broadband beamforming [5], [6]. These problems typically involve parahermitian polynomial matrices, which are identical to their parahermitian conjugate, i.e., [4]. Such a matrix can arise as the z-transform of a space-time covariance matrix .