Development of the sheet-type electromagnetic wave absorber for ETC/DSRC

摘要

DSRC (Dedicated Short Range Communication), which is a communication system for high-speed transportation, uses microwave of the 5.8 GHz band and has been used as ETC (Electronic Toll Collection) for the public since 2001. In the near future the DSRC is expected to expand into various private fields. Under such circumstances, the wave absorber which adjusts the electromagnetic environment and secures the reliability of communications will be applied to various places in many forms. We have developed wave absorbing panels for the canopy of tollgates on the expressway which are installed all over the country. Many lands of the wave absorbers are necessary for various installing situations (e.g. curved surfaces, small and complicated places). This report describes the development of a thin sheet type wave absorber suitable for these situations. Our sheet type wave absorber designed by transmission line theory and for use under the circularly polarized wave realizes absorption performance which meets ETC specifications by JHRI (Japan Highway Public Corporation Research Institute) at only 1.9 mm in thickness. Furthermore, it is very flexible and easy to cut into any size or shape, so it can be used for any purpose. We expect that our sheet-type wave absorber will contribute to the early realization of the DSRC system.