Sidelobe mitigation in MIMO radar with multiple subcarriers

This paper presents the studies on the reduction of peak sidelobe level in distributed MIMO radar with multiple subcarrier signals. Multiple subcarriers with sufficient frequency spacing become an alternative to increasing the number of sensors for sidelobe reduction. It is shown that the multiple subcarrier signals are most effective in reducing sidelobes at locations far from the target. Two signaling methods, namely continuous carrier transmission and Gaussian-OFDM signals are studied with respect to the sidelobe mitigation properties. The paper also presents an upper bound to the peak sidelobe level considering the non-coherent combining. It is shown that with non-coherent combining, the peak sidelobe of the localization metric scales down as 1/MNLsin(3π/2L) where L is the number of subcarriers, and M, N are the number of transmit and receive sensors. While there are grating lobes present in the metric with non-coherent combining, there is a grating lobe free region around the mainlobe, lower bounded by ρ = ±Lρ0/2B . With coherent processing, multiple subcarriers are effective in reducing the sidelobes as well as grating lobes.