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Construction of smart city has become a historical trend in the world. The management of underground pipes and the intelligent concrete are the main part of building smart city in China. Compared with the available electronic marker system, SAW-RFID system has shown excellent properties: truly passive, strong penetrating capability, long service-life, sensing and ID integration, and etc. Thus, SAW-RFID...
Some methods to enhance penetration depth further are proposed and demonstrated. A second harmonics SPUDT, new criterion of matching and high reflectivity reflector are utilized to reduce the losses of SAW tag. The enhancement of reading system including high signal processing gain and compensate the center frequency mismatch between reader and SAW tag are achieved. Furthermore, the effect of decreasing...
The piston mode operation (PMO) is quite effective for realization of spurious-free and low-loss SAW resonators. The scalar potential (SP) analysis indicates that “phase shifters” are necessary for PMO at edges of the acoustic aperture. Nakamura, et al., pointed out that for SAW resonators using SiO2/LiNbO3 structure, PMO is possible by simply removing SiO2 in the dummy electrode region [1]. This...
This paper proposes a frequency domain analysis (FDA) based on the finite element method (FEM) for calculating reflector scattering characteristics of SAW tags. This method is applicable not only to devices employing conventional single-crystal substrates but also multi-layered ones. First, reflection characteristics are calculated for a short reflector on 128°YX-LiNbO3 and compared with the result...
In order to obtain the exact time delay of pulses in the surface acoustic wave (SAW) based radio frequency identification (RFID) at unknown temperature, we propose a method for obtaining a high phase ambiguity resolution by measuring group delays and constructing some restriction on the exact positions of reflectors. To define the restriction parameters for a SAW RFID system with large code capacity...
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