A Complex Low-RCS Antenna System for the Placement of mm-Wave Automotive Radars behind Car Bumpers

Abstract

Automotive radars are one of the key sensor technologies to develop reliable fully-automated cars. They are usually installed behind the bumper of the vehicle and therefore, multiple reflections can occur. The multiple reflections can be mitigated with the use of low-RCS (radar cross-section) antenna arrays. This paper presents the design of a complex low-RCS multiple antenna system that mimics a typical MIMO (multiple-input multiple-output) configuration. A prototype has been developed and tested. Approximately 17 dB of RCS reduction has been experimentally achieved. The measurement results show that the use of such a low-RCS antenna system can successfully reduce the amplitude of multiple reflections. Index Terms-radar cross-sections, microstrip antenna arrays, radar antennas, millimeter wave radar.

Characterization of a mm-Wave Automotive Radar with a Low-RCS MIMO Antenna System

“…The AMC should be designed so that destructive interference can be achieved in the wave reflected back by the AMC and the antenna. Following this approach, the antenna arrays developed in [4] and [5] showed a significant RCS reduction compared to the same array without the AMC.…”

“…The reduction of the RCS can be formally described by [5]: then that the equation 1is a weighted average of the amount of power reflected back by the AMC and the antenna [5].…”

“…Due to the complexity of the MIMO configuration, it is not possible to perform a full-wave simulation of the complete antenna system for the calculation of the reflection coefficient required in (1). For this reason, an empirical design approach has been used, similar to the one proposed in [5]. However, while in [5] the terms A ant and ϕ ant relative to the whole MIMO configuration were estimated with measurements, in this work the starting point for the design is the simulation of the 2-element slotted-patch array.…”

“…For this reason, an empirical design approach has been used, similar to the one proposed in [5]. However, while in [5] the terms A ant and ϕ ant relative to the whole MIMO configuration were estimated with measurements, in this work the starting point for the design is the simulation of the 2-element slotted-patch array. It is assumed that the reflection coefficient of the whole MIMO antenna system is similar to the one of the 2-element array.…”

“…Some previous works [4], [5] proposed the use of low-RCS antennas as a possible solution to mitigate the multiple reflections between radar sensor and painted bumper. If the radar is equipped with such an antenna system, it can scatter back less power in boresight direction towards the bumper, while redirecting the impinging wave towards different directions other than the boresight.…”