Sparse Random SAR Trajectories for a Millimeter Wave 3D Radar Scanner

By use of a simplified mathematical model assuming far-field conditions and time-harmonic transmitted electromagnetic waves, the SAR trajectory (SAR = synthetic aperture radar) for a millimeter wave 3D radar scanner is identified with a planar (2D) synthetic array. Design criteria for sparse random SAR trajectories are formulated by adapting the well-known theory of conventional random arrays to the case of synthetic random arrays. Theoretical results are verified by numerical simulations and experiments. An example of a sparse synthetic random array with high angular resolution and reasonable sidelobe suppression is presented, which uses only about 1% of the number of measurement positions in a full synthetic array of the same size (i.e., an array with periodically distributed measurement positions, satisfying some Nyquist condition). This implies an enormous reduction of measurement time and of the amount of raw data.