I. Introduction
RECENTLY, multichannel radar systems have attracted more and more attention due to their superior performance on target detection, tracking and imaging [1], [2]. These radar systems encompass various types such as multiple-input-multiple-output (MIMO) radar [3], [4], simultaneously polarimetric radar (SPR) [5], [6], and randomly polarimetric radar [7]. Generally, they transmit a set of orthogonal waveforms through multiple transmitting channels and then process the received echo signals by all receiving channels using a bank of matched filters. The waveform orthogonality plays a critical role in mitigating the mutual interference between the output signals of filter bank [8]. Accordingly, by ensuring waveform orthogonality, multiple transmitted waveforms can be effectively separated at the receiver end [9], [10].