Polarimetric radar measurements for vehicle control and warning applications

The idea to use a radar for automotive braking and even steering is not new. Some 35 years ago, in the mid-sixties, the Radiation Laboratory made RCS measurements on tree trunks, stop signs, cement walls, and humans to determine if the targets could be identified from the (limited) RCS data. Unfortunately the results were not encouraging. For example, a tree truck along the side of a road could have similar return magnitude as a human. At that time only single-frequency and co-polarized data, are available. The introduction of radar polarimetry technique provides a new approach to achieve the goal of the early study. Since 1995, the Sarabandi group from the Radiation Laboratory has successfully developed models to predict the backscatter response from road surfaces and to detect debris and faults on road surfaces. In this article, the theory behind the analytical modeling is explained. Then, the experimental results are presented to justify the validity of the developed models.