Improving the Short-Range Perception of MIMO Radars with LO Feedthrough Topologies by Complex Sampling

In radar systems with local oscillator feedthrough topology, range shifts occur due to the time delays between the radar transceivers. These shifts can be corrected efficiently in postprocessing, except for the short-range spectrum, as disturbing peaks, caused by range shifts of the transmit-to-receive leakage, prevent the use of such system in short-range applications like automated parking. In this contribution, the capabilities of complex sampling, compared to real sampling, are analyzed both in theory and by measurements, with respect to the effects in systems with feedthrough topology. The imaging performance at very short ranges is investigated with an exemplary scenario, representing a typical automated parking situation. The measurements show that with complex sampling, the image peaks vanish and the noise level is reduced by 2.8 dB. In this way, radar images suitable for automated parking and other short range applications can be obtained.