Range-Angle Decoupling Technique Using Wavelength-Dependent Beamforming for High-Resolution MIMO Radar

This article proposes a range-angle decoupling technique for use in a high-resolution multiple-input multiple-output (MIMO) radar system. A high-resolution radar system exploiting both a wide modulation bandwidth and a large array aperture is detrimentally affected by what is known as the range-angle coupling (RAC) effect. This effect severely degrades the angular resolution at off-boresight angles in conventional digital beamforming radar. To obviate this effect, a wavelength-dependent beamforming technique that adjusts the number of discrete Fourier transform (DFT) points simply along the quantized frequency within the modulation bandwidth is proposed and described here. After wavelength-dependent beamforming, a target range is estimated at each angle cell. This allows estimating both the range and angle of a target without angular resolution degradation of the off-boresight angle. It is validated through both simulations and experiments that the angular resolution can be improved by applying the proposed beamforming technique.