Härmä Sanna, Arthur Wesley G, Hartmann Clinton S, Maev Roman G, Plessky Victor P
Dept. of Eng. Phys., Helsinki Univ. of Technol., Helsinki.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Aug;55(8):1840-6. doi: 10.1109/TUFFC.2008.867.
Surface acoustic wave (SAW) radio-frequency identification (RFID) tags are encoded according to partial reflections of an interrogation signal by short metal reflectors. The standard encryption method involves time position encoding that uses time delays of response signals. However, the data capacity of a SAW RFID tag can be significantly enhanced by extracting additional phase information from the tag responses. In this work, we have designed, using FEM-BEM simulations, and fabricated, on 128 degrees -LiNbO3, inline 2.44-GHz SAW RFID tag samples that combine time position and phase encoding. Each reflective echo has 4 possible time positions and a phase of 0 degrees , -90 degrees , -180 degrees , or -270 degrees. This corresponds to 16 different states, i.e., 4 bits of data, per code reflector. In addition to the enhanced data capacity, our samples also exhibit a low loss level of -38 dB for code reflections.
表面声波（SAW）射频识别（RFID）标签是根据短金属反射器对询问信号的部分反射进行编码的。标准加密方法涉及使用响应信号时间延迟的时间位置编码。然而，通过从标签响应中提取额外的相位信息，可以显著提高SAW RFID标签的数据容量。在这项工作中，我们利用有限元-边界元法（FEM-BEM）模拟进行设计，并在128°铌酸锂（LiNbO3）上制造了结合时间位置和相位编码的内联2.44 GHz SAW RFID标签样本。每个反射回波有4个可能的时间位置和0°、-90°、-180°或-270°的相位。这对应于每个编码反射器16种不同的状态，即4位数据。除了增强的数据容量外，我们的样本对于编码反射还表现出-38 dB的低损耗水平。
