Conductive Fabric-Based Embedded Antenna Structures for Automotive Applications

The next generation of automotives will incorporate significant electronic components and sensors to meet the needs for safety, communication, efficient operation and comfort. Automotive parts are largely made from fiberglass composites as they provide a high strength-to-weight ratio, light weight, strength and stiffness in comparison to metal structures. Fiberglass is made of glass fibers and a polymer resin, similar to printed circuit boards. Embedded (or hidden) electronics within such composites have the potential to reduce labor and material costs while also enabling new approaches to systems packaging. Among the many components needed in automotive, antennas are crucial for next-generation vehicle connectivity. Toward this goal, this paper presents a novel process for fabricating conductive fabric antennas and other radio frequency (RF) structures integrated into the fiberglass-based structures. Two different conductive fabrics, copper (total thickness: 60 μm) and stainless steel (total thickness: 50 μm), are used. These conductive fabrics are laminated to fiberglass substrates using a photocurable resin material. This resin is first characterized over a frequency range of 50 MHz - 6 GHz. As a proof of concept, a few RF structures are designed and demonstrated to evaluate electrical performance, including microstrip transmission lines, resonators, half-width microstrip leaky-wave folded antennas, monopole coplanar waveguide (CPW) folded antennas and microstrip patch antennas. Details of the design, fabrication and measurements are provided in this paper.