Tomographic imaging of radar data gathered on a circular flight path about a three-dimensional target zone

We have coded a tomographic-style algorithm that is capable of imaging radar data obtained on a circular flight path about a 3D target zone. Our imaging algorithm is designed to image field data collected with Mireage's new Subsurface Imaging Synthetic Aperture Radar (SISAR), a ground-penetrating device operating in the spotlight mode. The SISAR algorithm operates on radar data gathered in (or converted to) the range-azimuth domain--the so-called sinogram plane. On the sinogram plane, the impulse response of a point scatterer is sinewave- shaped curve. The amplitude of the sinewave is related to the target's radial coordinate, its phase to the target's azimuthal coordinate, and its bias to the target's burial depth. When flown on a circular path about a 3D target zone, SISAR generates 3D-style sinograms. Our imaging algorithm produces 3D maps of the target zone by converting each sinewave trace on the sinogram plane to a delta function in three-space. The code is fast (in the FFT sense). Moreover, it avoids the laborious, and often inaccurate conversion of the collected radar data from cylindrical coordinates to rectangular ones, as in conventional radar imaging.