Radar Imaging Using Electrically Large Arrays With High Range Resolution at 160 GHz

In order to improve the resolution of imaging radars, electrically large arrays and high absolute bandwidths are required. At a large off-boresight angle of the incident wave, the difference in path length at the antennas becomes a multiple of the range resolution of the radar. Consequently, the radar responses of the targets at the different receiving channels are distributed over a large number of range bins, depending on the direction-of-arrival (DoA) of the target echo. Applying conventional signal processing, the resolution of the radar is considerably reduced. In this paper, the key aspects of DOA estimation are discussed when radars with both a large aperture size and a high absolute bandwidth are employed. A signal processing method is proposed avoiding errors that occur in conventional DOA estimation techniques. As shown by measurements, an angular resolution of 0.4°can be achieved with an array size of 200 An and a bandwidth of 10 GHz.