Long range wireless SAW passive tag system for vibration monitoring

In this paper, we describe a 920 MHz band long range wireless SAW passive tag system (WSPTS) for vibration monitoring, which achieves more than 10m reading distance. For the purpose of structural health monitoring (SHM) of aging infrastructures (e.g. bridge, building, and so forth), passive wireless sensor systems are an attractive option because they are operated battery-less and almost maintenance free. A SAW based passive tag system is suitable for the purpose; however, a conventional WSPTS is mostly limited to short range of less than 5m.