Wideband MIMO Frequency-Modulated Emission Design With Space-Frequency Nulling

摘要

A design approach is presented that jointly optimizes the beampattern and spectral content of a wideband multiple-input multiple-output (MIMO) radar emission within the context of physically realizable frequency-modulated (FM) waveforms emitted from a uniform linear array. Such waveforms minimize the distortion induced by the power amplifier by virtue of being constant amplitude and inherently well-contained spectrally. The design approach is a specific form of alternating projections that shapes the emission spectrum as a function of spatial angle while intrinsically addressing the problem of reactive power that arises for the wideband MIMO emission. This scheme also permits incorporation of joint space-frequency nulling to facilitate spectrum cohabitation with other nearby RF users. The design process is performed in a discretized manner that is oversampled relative to waveform 3-dB bandwidth to capture a sufficient portion of the spectral roll-off to realize the physical waveform, which is subsequently implemented via the polyphase-coded FM structure.