Short Range Imaging with Optimized Sparse Array
This paper presents a MIMO imaging system on the basis of a hybrid concept with synthetic aperture radar (SAR) and digital beam forming (DBF). By moving a multistatic linear array perpendicular to the array dimension a two dimensional aperture is sampled. The scope of application is the field of non destructive testing (NDT) and security systems. Thus the frequency range 75-90 GHz seems to be a good compromise between lateral resolution and penetration depth. A moderate number of transmit and receive channels is 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. Therefore an optimized array was developed as well as a post processing algorithm on the basis of a notch filter. This notch filter is applied to attenuate the main part of the ambiguous energy in the doppler spectrum. Results are demonstrated with simulated and measured data.
