Multichannel Repeater for Coherent Radar Networks Enabling High-Resolution Radar Imaging

Coherent radar networks allow for spanning very large apertures that include all sensors with their subapertures in the network, resulting in very good angular resolution. However, as a radar network typically has a sparse array, its performance depends on the flexibility of the antenna and network node placement. Thus, in this work, a new type of radar network is presented, allowing for a highly flexible network and array design and providing an excellent performance in direction-of-arrival (DoA) estimation. This is reached by using multichannel repeaters (MCRs) in combination with a single multiple-input multiple-output (MIMO) radar. The multichannel repeaters (MCRs) receives the radar’s signal via a line-of-sight path, and then re- transmits it via multiple transmit channels, each with a dedicated mixer used for multiplexing. To show the feasibility and the performance of this concept, a 77- <inline-formula> <tex-math notation="LaTeX">$\mathrm { \text {G} \text {Hz} }$ </tex-math></inline-formula> radar network consisting of a digital <inline-formula> <tex-math notation="LaTeX">$4\,\, \times 4$ </tex-math></inline-formula> multiple-input multiple-output (MIMO) radar and two four-channel MCRs is presented. It is designed following network array design recommendations mathematically derived in this work and combined with an adapted signal processing and network-based direction-of-arrival (DoA) estimation. The high performance of the system is demonstrated not only via systematic measurements in an anechoic chamber, but also in various automotive scenarios including multiple road users.