Imaging applications of millimeter wave sensors in robotics and road traffic

Many tasks that can be fulfilled by millimeter wave sensors are in principle the solution to 2-D or 3-D imaging problems. After a recapitulation of the basics of obtaining 3-D resolution in spatial frequency domain the various methods of obtaining longitudinal resolution such as pulse, pulsed FM, FMCW and PN modulation are discussed as well as principles to achieve lateral resolution in one or two dimensions. The corresponding methods of mechanical beam scanning, phased array antennas, wavefront reconstruction or digital beam forming are reviewed with respect to sensor applications. Advanced methods of using a transmitter antenna diversity to efficiently use a given array of a limited number of receiver antennas are described according to this scheme. Most of the principles are underlined by examples of systems which have been realized at TUM. All systems parameters related to spatial resolution can be efficiently characterized and compared in spatial frequency domain.