声表面波标签三次反射的分析

声表面波(SAW)射频标签中排列在一行的反射栅形成的三次反射造成了编码信号间的幅度不一致,破坏了有、无反射栅间的幅度动态范围,提高了对标签解码的要求。该文利用脉冲响应模型,推导了三次反射与每条反射栅的位置、反射系数和透射系数的关系。通过计算反射栅均匀排列的脉冲幅度编码标签的三次反射,与已有文献结论对比,验证了模型的有效性。仿真了非均匀排列、幅度补偿的脉冲位置编码标签的三次反射,提前预测了最大三次反射出现的位置和大小,为确定标签的查询周期、最后一条反射栅的反射系数以及增加相位编码信息设计提供了参考。

Triple Reflections in Surface Acoustic Wave Based RFID

The multiple reflections in surface acoustic wave based radio frequency identification tag(RFID) give rise in the non-uniformity of all reflected echoes and the bad separation between the lowest echo and the highest spurious reflections within the response time.We utilizing the impulse response model,the relationship among the triple reflections and the position,reflectivity and transmission coefficient of each reflector is deduced.We first calculate the triple reflections of an amplitude modulation SAW RFID.The validity of the model is given by comparing the above results and the published conclusion.However,the conclusion is only valid for tags whose reflectors are proportional spacing arranged.The maximum and position of the triple reflections in a pulse position modulated by SAW RFID,whose reflected echoes are amplitude compensated,are estimated in advance.The simulation is used for determining the reflectivity of the last reflector and estimating the influence of tripe reflections on the phase of reflected echoes.