Airborne and groundbased passive millimeter-wave imaging at 37 and 90 GHz

Passive microwave imaging with conventional linescanner systems is an extensively proofed technique with a long tradition and experience in civil and military application fields. During the last couple of years another promising technique, the aperture synthesis method, has become more of interest because of the principal possibility to generate 2D images without moving the aperture. In the first past of this paper, representative measurement results are shown from a 90 GHz linescanner system, cooled with liquid nitrogen, with a spatial and radiometric resolution of 1 degree(s) and 1.7 K for flight measurements, respectively. In the second part, a groundbased aperture synthesis radiometer imaging system at 37 GHz is described. Basically the system consists of a two-element interferometer with a variable baseline, which enables the complete sampling of the uv- plane sequentially. As a consequence this imaging equipment is only suited for the mapping of stationary targets. Experimental measurement results are demonstrated which were acquired in the near and far field with a spatial resolution of 0.6 degree(s) and a temperature resolution of about 1.5 K.