K. Sarabandi et Es. Li, Polarimetric characterization of debris and faults in the highway environment at millimeter-wave frequencies, IEEE ANTENN, 48(11), 2000, pp. 1756-1768
In this paper, measurements and models for the polarimetric backscatter res
ponse of various point targets on roads and road surface faults is presente
d. Of particular interest are debris and faults that could lead to fatal ac
cidents and damage of property. A desired safety feature for automotive rad
ar sensors is the capability of detecting such debris and faults. The detec
tability of a point target is evaluated by comparing its RCS value with the
RCS threshold value defined by the backscatter response of the road surfac
e. Extensive backscatter measurements at W-band were conducted to obtain th
e backscatter response of typical debris and faults on asphalt surfaces at
near grazing incidence angles (76 degrees -86 degrees). On the other hand,
theoretical models, based on diffraction from impedance wedges and scatteri
ng from impedance cylinders, respectively, as well as physical optics appro
ximation, were developed to predict the backscatter response of road surfac
e faults and targets with planar facets on road surfaces. Experimental resu
lts indicate that detectability in all cases is a function of target size,
its azimuthal angle with respect to radar boresight, and the polarization s
tate of the system. The measured backscatter response is used to verify the
validity of the theoretical models. Angular polarimetric backscatter measu
rements of targets defining roadside boundaries such as a concrete curb, a
guardrail, and a pebble surface are also presented. The results of these me
asurements could be used to alert fatigued drivers should their vehicles be
heading sideward.