Passive Millimeter-Wave Dual-Polarization Imagers

We have developed two passive millimeter-wave imagers for terrestrial remote sensing: one is an integrated imaging and spectroscopy system in the 146-154-GHz range with 16 channels of 500-MHz bandwidth each, and the other is a single-channel dual-polarized imaging radiometer in the 70-100-GHz range. The imaging in both systems is implemented through translation of a 15-cm Gaussian dielectric imaging lens. We compared the outdoor images of objects such as car, vegetation, sky, and ground by both the systems under various weather conditions, including clear, cloudy, and rainy times. A ray-tracing simulation with radiative transfer equation was used to quantify the polarization diversity of the acquired images.