Modeling the performance of automotive bumper mounted antennas

In order to improve automobile driver safety, manufacturers are exploring a variety of sensing options. A collision avoidance radar is a possible device that provides an all-weather, day-night sensing capability. Systems of various complexities are possible, but they all require an effective antenna system. This paper explores the effects of mounting a small array behind an automobile bumper fascia. This is similar to the standard radome problem. However, the system designer has little input on the make up of the bumper fascia, in terms of thickness, paint, and relative position of antenna and material. Material properties for this study are determined by transmission line measurements for samples of the plastic fascia with and without several different paints. Gain calculations for a patch array in various combinations of bumper configurations are found. The analysis is performed using uniform geometrical theory of diffraction (UTD) techniques. Validation is provided by measurements made in the OSU-ESL compact range.