Radar sensor antenna with anti-reflection element
| Inventors: | Purden; George J. (Westlake Village, CA), Shi; Shawn (Thousand Oaks, CA) | ||||||||||
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| Applicant: |
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| Assignee: | Delphi Technologies, Inc. (Troy, MI) | ||||||||||
| Family ID: | 1000001566424 | ||||||||||
| Appl. No.: | 14/035,101 | ||||||||||
| Filed: | September 24, 2013 |
BACKGROUND OF INVENTION
It is known to place a radar sensor behind a fascia of a bumper of a vehicle for detecting objects proximate to (i.e. in front of or behind) the vehicle. As used herein, the fascia is a decorative cover placed over the impact absorbing portion of a modern bumper assembly. The fascia is generally for making the vehicle more attractive. Such a fascia is typically formed of a polymeric compound so that an emitted signal output by the radar sensor can propagate through the fascia toward an object proximate to the vehicle, and a reflected signal reflected by that object can propagate back through the fascia to be detected by the radar sensor. The configuration (e.g. material(s), thickness, orientation) of the fascia is typically selected to minimize interference with the electromagnetic signals propagating through the fascia. However, some reflection of the emitted signal by the fascia may be unavoidable for a number or reasons. This form of signal reflection is sometimes characterized as an early reflection by the fascia of the emitted signal output by the radar sensor. This early reflection may reflect back and forth between the antenna and the fascia, and possibly interfere with the detection of the reflected signal reflected by an object on the other side of the fascia. It has been proposed to place or apply electromagnetic energy absorbing material proximate to the
antenna at the locations that don't interfere with transmitting or receiving electromagnetic signals, but do help to absorb this early reflection. However, adding such absorbing material adds undesirable
cost to the radar sensor.
Reference/Background:
- Marhefka, Ronald J.; Baertlein, B.A.; Rao, M.; Prakah-Asante, K., "Modeling the performance of automotive bumper mounted antennas," in Antennas and Propagation Society International Symposium, 2002. IEEE, vol. 3, no., pp. 316-319 vol. 3, 2002.
Abstract: 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 - Remcom_EMSimulation_Automotive_Radar_inVehicle_Bumper.pdf
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