Millimeter-Wave Imaging With Optimized Sparse Periodic Array for Short-Range Applications

This paper presents a multiple-input-multiple-output imaging system on the basis of a hybrid concept with synthetic aperture radar and digital beam forming. By moving a multistatic linear array perpendicularly to the array dimension, a 2-D aperture is sampled. The scope of application is concealed weapon detection in conjunction with the imaging of humans and, alternatively, nondestructive testing (NDT). The frequency range of 75-90 GHz was chosen because of the inherent high lateral resolution. For NDT, it seems to be a good compromise between lateral resolution and penetration depth as well. A moderate number of transmit and receive channels are achieved by a sparse periodic array (SPA) design. Since this is a far-field approach, ambiguities are not well suppressed in the near-field point spread function of the sparse array. An extension of the SPA concept for short-range applications on the basis of an optimized array design and an optimized beamforming algorithm is presented in this paper.