The paper presents a broadband CW imaging technique using an unfocused free space reflection measurement setup in W-Band (75-100 GHz). The goal is to achieve a spatial highly resolved 3D-image of a dielectric device under test (DUT) in order to detect cracks or other defects up to a size of 1-2 mm. After the data collection, numerical post processing is applied to the unfocused rawdata in order to achieve a highly resolved 3D-reconstruction of the DUT. Two approaches are realized, the first one is a special Synthetic Aperture Radar (SAR) algorithm called Range Migration Algorithm (RMA). The second one is a deconvolution algorithm based upon a constrained least squares (CLS) method. Latter reconstruction techniques require coherent signal detection. Therefore a heterodyne frequency stepped measurement setup was developed. This setup is realised with a commercial network vector analyzer (VNA) which allows a fast and accurate measurement of a broadband frequency response of the DUT. The data collection is either realized in a planar or cylindrical scanning geometry. Both cases are examined. Furthermore spectral estimation techniques are applied to the broadband measurement data to overcome the limitations of the range resolution, achieved by conventional processing techniques.
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