# Car Bumper Effects in ADAS Sensors at Automotive Radar Frequencies
## 6 Conclusions  
We measured the attenuation that different samples of car bumpers cause in the propagation of the electromagnetic signals at the working frequency band of automotive radar. These results are of interest in a time of strong development of ADAS, in which locally gathered information could be shared in the future, integrated into the wide coverage and rapidly developed ITS technology [5]. Curved and flat bumper samples were analyzed. In the curved samples, more variability was observed, probably due to the curvature itself and the air gaps between the sample and its holder. Despite this, the attenuation trend and their orders of magnitude were the same in both cases. We observed that the attenuation has a decreasing trend with the frequency in all samples evaluated, with values below 1.25 dB in the whole band (or 1.44 dB if we consider the uncertainty) for the flat samples. Such values of attenuation imply a reduction in the detection range of 6.7 m, 13.4 m and 33.5 m for radars configured to range for detection distances of 50 m, 100 m and 250 m, respectively, if the penetration losses could not be compensated by increasing the transmitted signal. Samples with a thicker varnish layer led to higher attenuation values. Also, the paint composition could explain the attenuation differences among the samples, due to the higher imaginary part of the permittivity of paints that contain metallic particles. Figure 11: Measured attenuation of bumper samples A.2 and D.2. Dotted lines represent attenuation measurements without absorbers covering the multiplier and the back of the antennas, and the solid lines represent the measurements after adding the absorbers. * (11) Anritsu Corporation; Fraunhofer FHR. E-Band Based Car Radar Emblem Measurements. Application Note 11410-01152, Rev. A. 2019. Available online: [[https://dl.cdn-anritsu.com/en-us/test-measurement/files/Application-Notes/Application-Note/11410-01152A.pdf](https://dl.cdn-anritsu.com/en-us/test-measurement/files/Application-Notes/Application-Note/11410-01152A.pdf)]([https://dl.cdn-anritsu.com/en-us/test-measurement/files/Application-Notes/Application-Note/11410-01152A.pdf](https://dl.cdn-anritsu.com/en-us/test-measurement/files/Application-Notes/Application-Note/11410-01152A.pdf)) (accessed on 18 September 2023). * (12) [PERSON] Analysis on the Installation of Long-Range Radar Sensors in Modern Vehicles. Master's Thesis, Mechatronic Engineering, Politecnico di Torino, Turin, Italy, 2022. * (13) [PERSON]; [PERSON]; [PERSON] Evaluating 77 to 79 GHz Automotive Radar Radome Emblems. _Microw. J._**2018**, _61_, 70-78. * (14) [PERSON]; [PERSON] [PERSON] Influence of resin cover on antenna gain for automotive millimeter wave radar. In Proceedings of the International Symposium on Antennas and Propagation (ISAP), Okinawa, Japan, 24-28 October 2016; pp. 704-705. * (15) [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON] An Improved Performance Radar Sensor for K-Band Automotive Radars. _Sensors_**2023**, _23_, 7070. [CrossRef] [PubMed]
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