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Development of a millimeter-wave transparent antenna inside a headlamp for automotive radar application

Published online by Cambridge University Press:  27 April 2022

Sofian Hamid
Affiliation:
Institute of High Frequency Technology (IHF), RWTH Aachen University, Aachen, Germany
Dirk Heberling
Affiliation:
Institute of High Frequency Technology (IHF), RWTH Aachen University, Aachen, Germany Department Ablation and Joining, Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR), Wachtberg, Germany
Manuela Junghähnel
Affiliation:
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (FEP), Dresden, Germany
Thomas Preussner
Affiliation:
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (FEP), Dresden, Germany
Patrick Gretzki
Affiliation:
Department Ablation and Joining, Fraunhofer Institute for Laser Technology, Aachen, Germany
Ludwig Pongratz
Affiliation:
Department Ablation and Joining, Fraunhofer Institute for Laser Technology, Aachen, Germany
Christian Hördemann
Affiliation:
Department Ablation and Joining, Fraunhofer Institute for Laser Technology, Aachen, Germany
Arnold Gillner*
Affiliation:
Department Ablation and Joining, Fraunhofer Institute for Laser Technology, Aachen, Germany
*
Author for correspondence: Arnold Gillner, E-mail: arnold.gillner@ilt.fraunhofer.de

Abstract

The development of a millimeter-wave transparent antenna integrated inside a headlamp for automotive radar application is presented. The antenna consists of two radiating elements: the primary and secondary ones. The primary antenna is the one that is fabricated on RF PCB material (e.g., patch, slot, sectoral horn) and connected directly to the transceiver chip, while the secondary antenna is made of optically transparent materials such as glass, but with a optical transparent electrically conductive coating, well known as transparent conductive oxide (TCO). This antenna is realized as a planar offset reflector to collimate and shape the incoming wave from the primary antenna. This reflector is designed based on the Fresnel theory and the reflectarray concept. The division of the primary and secondary antenna enables the placement of the radar module (that contains the primary antenna) at the base of the headlamp, and therefore it is concealed from the surroundings and hidden from the optical path of the light. The secondary antenna is inserted in the space between the headlamp cover and the light unit. The main challenge here is to provide a maximum on transparency in the visible range of the spectrum with a specially designed and laser-based generated microstructure for the resonant reflection of the radar wavelength. An antenna demonstrator has been fabricated, and together with the headlamp cover, the radiation pattern and realized gain are measured. We reported here the measurement results for several reflector designs and concluded that the headlamp cover gives minimal influence on the antenna performance.

Type
EuCAP 2020
Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press in association with the European Microwave Association

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