Metamaterial absorbers for 24-GHz automotive radar applications

Abstract

Absorbers for automotive radar applications must satisfy some requirements such as a wide incident angle, polarization insensitivity, flexibility, low-profile structure, and low cost. To satisfy these requirements, we propose two types of metamaterial absorber for a 24-GHz automotive radar system. The first absorber is composed of 60x60 equally spaced unit cells with an electric LC resonator, a substrate, and a ground sheet. It has a peak absorptivity of 99.7% at 24.1GHz and total full-width at half-maximum (FWHM) of 1.0GHz. To increase the FWHM, a bandwidth-enhanced absorber was designed by arranging the unit cells into an optimized offset sub-array structure. The proposed absorber exhibited peaks at 24.1 and 25.2GHz with absorptivities of 97.8 and 74.5%, respectively. The FWHM improved by 900MHz compared with that of an equally spaced absorber. The measured results of the fabricated absorbers agreed well with the simulated ones.