Automotive systems designers encounter unique problems with the development and deployment of high frequency radar systems in vehicles. Chief among these are• cavity resonances within metal enclosures• coupling between transmit and receive antennas• refl ections caused by adjacent metal structures on the vehicle• focus of the antenna pattern

Resolution of these problems can be a complex task that may includecircuit and antenna layout, enclosure design compromises, range and pattern concessions and placement within the vehicle.

A sensible solution is the selection of high frequency radar absorbing materials suitable for the automotive environment.

In addressing the needs of automotive radar designers ARC Technologies has drawn upon its 25 years of experience as the leading supplier of radar absorbing materials for military, aviation, marine and commercial applications to design solutions that can be technically advanced, cost effective, lightweight and durable.

Material selection is critical to the resolution of radar resonance and interference issues. The ARC R&D team of physicists, metallurgists, chemists as well as thermoplastics and material engineers has created an assortment of optimal materials which can be formulated, molded or otherwise fabricated to best suit the application.

ARC tested a large number of materials at various frequencies and selected 4 materials that would work in the “K” and “W” bands.

Absorber for Automotive Radar Sensors

•L-band •2-18GHz•”K” 18-40GHz •”W” 75-110GHz

technical bulletin

ARC Technologies • 11 Chestnut Street, Amesbury, MA 01913 • 978.388.2993

www.arc-tech.com

ARC offers a selection of materials to the users since every application is slightly different. Sometimes the material strength is slightly more important, other times it is the Absorption.

Please contact an ARC sales engineer for a detailed data sheet and advice on further selection.

ARC Technologies tested the materials with a WR-42 Waveguide in the “K” 18-26.5 GHz band, and used a focused beam system with a broadband dielectric lens to test the material samples in the “W” 75-110GHz band. Materials were tested in two orientations (90deg apart) and the results were averaged.

The following chart is ARC Technologies recommendation for materials in the 24, 77-100 GHz range.

ARC PN PP1003 PP1000 PA1000 26000Polymer Polypropylene Polypropylene Nylon Silicone

Absorptive Material Carbon Carbon Carbon Carbon

Attenuation @ 24 GHz (dB/cm) 57.2 110.6 30.4 47.4

Attenuation @ 77 GHz (dB/cm) 86.5 136.7 71.3 81.5

Attenuation @ 95 GHz (dB/cm) 84.1 143.2 62.5 76.7

Attenuation @ 110 GHz (dB/cm) 82.9 138.9 57.6 74.9

Test Sample Thickness (mm) 6.22 6.19 6.33 3.58

Permittivity @75 GHz 4.82 6.67 5.58 5.30

Permittivity Imag @75 GHz 1.61 3.83 0.93 1.38

Permittivity @95 GHz 4.61 6.11 5.40 5.11

Permittivity Imag @95 GHz 1.48 3.38 0.95 1.33

Permittivity @110 GHz 4.48 6.09 5.28 4.99

Permittivity Imag @110 GHz 1.40 2.85 0.96 1.29

UL 94 V-0

Application Molded part Molded part Molded part Gasket, die cut

Manufacturing form Injection molded Injection molded Injection molded Sheet stock