Improvement in 77-GHz Radar Cross Section of Road Work Jacket and Side Screen by Use of Planar Flexible Retrodirective Reflectors

Many road vehicles are today equipped with 77-GHz radar systems for improved road safety. Some objects on the roads, e.g., pedestrians, give a poor reflection of the radar signal. Two applications are studied in this letter: jackets with the reflectors integrated in the lining, and plastic side screens of the type used at road work. A special type of radar reflector is designed, which would be suitable for these applications. The reflector used is a thin and flexible retrodirective microstrip patch antenna array. Panels of suitable size containing a number of these reflectors can be applied to the jacket and the side screen. The improvement in radar cross section is measured. Various design aspects of the chosen reflector, and a comparison to alternative techniques, are discussed.