A Low-Profile Passive Radar Reflector for Detection and Identification of Road Markings

This article presents a design for a very low-profile passive reflector device, which presents a large radar cross section (RCS) to forward looking automotive radar. With a total height of less than 0.25 mm, the reflector can be embedded in the paint of road markings, enabling the markings to be detected and identified with radar. This will allow radar to supplement several advanced driver assistance systems (ADAS) currently delegated only to camera sensors, and to improve reliability in poor-visibility and inclement weather conditions. The proposed reflector is designed for operation at the 77-GHz automotive radar band. Fabricated prototypes exhibit measured RCSs of about −13 dBsm, which is large enough to provide more than 20 dB of signal to background for typical underlying asphalt surfaces. It is also demonstrated that spatial patterns of several reflectors can be resolved by radar and used to encode different markings. Finally, with the goal of advising future development, a study of the effects of dielectric materials and water on reflector performance is conducted.