Coherent Measurements of a Multistatic MIMO Radar Network With Phase Noise Optimized Non-Coherent Signal Synthesis

Abstract

For multistatic radar networks in the upper mm-wave range with a large spacing between its radar sensor nodes, a coherent signal distribution is very complex and thus very costly. Hence, it is desirable to generate the mm-wave signals individually for each radar sensor node, i.e., non-coherently. However, multistatic radar networks using a non-coherent signal distribution for its radar sensor nodes are affected by systematic errors and uncorrelated phase noise, which reduces the resolution and the detection performance of these systems. In this article, a novel non-coherent signal synthesis concept based on the direct digital synthesis (DDS) principle is presented for multistatic radar networks. Compared to a signal synthesis using a phase-locked loop (PLL), it is shown that the different phase noise behavior of the DDS is beneficial for bistatic signal paths between the radar sensor nodes. The presented hardware concept is considered and analyzed for three different types of coherency regarding the signal distribution: coherent, quasi-coherent, and incoherent. Measurements with a multiple-input multiple-output (MIMO) radar at <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex>$150 \,\mathrm{G}\mathrm{Hz}$</tex></formula> prove that despite a non-coherent signal distribution, it is possible to achieve the same detection and imaging performance as with a fully coherent radar by using a DDS.