A Multi-Channel Radiometer with Focal Plane Array Antenna for W-Band Passive Millimeterwave Imaging

Passive millimeter wave imaging can complement security measures in scenarios such as airports or checkpoints, due to the fact that these frequencies penetrate clothes and enable e.g. concealed weapon detection (CWD). Such a radiometric system has to meet several key requirements concerning its thermal and spatial resolution and the image acquisition time. The latter can be reduced significantly by scanning the scene with multiple beams simultaneously. The demonstrator system presented in this paper describes a multi-channel focal plane array (FPA) approach that cuts the overall scanning time down by a factor of four. Dielectric rod antennas are proposed as feed elements in high density arrays. The dielectric wide angle lens of the FPA is focused at a distance of 20 m for stand-off measurements. Besides addressing the design and characterization of both the antenna setup and the radiometric receivers, measurement results are presented to demonstrate the feasibility of the multi-channel concept