Interferometric focusing for the imaging of humans

Different recent approaches have demonstrated the feasibility of applying millimetre-waves (MMW) for the imaging of objects at a person's body. The utilisation of MMW allows for the detection of both metallic and non-metallic objects. In order to reduce costs a low number of transmit-receive modules should be used. Furthermore, the person should also be illuminated from different angles in order to avoid shadowing effects as good as possible. A way to fulfil these two conditions is to place one sensor above and another one below the person and either rotate the person standing on a turntable (inverse synthetic aperture radar, ISAR) or move the sensors on a circular path around the person (synthetic aperture radar, SAR). The goal of the reconstruction is to obtain information about the shape of possible threats and their positions in all three dimensions. During processing as a first step, the reconstruction is done along range and azimuth, which span the principal surface given by the suggested sensor configuration. Afterwards, the third spatial dimension can be determined by combined evaluation of the resolution capabilities of the curved synthetic aperture and the interferometric phase of two coherent receiving channels of one sensor.