无线声表面波辨识标签的分析和设计

Analysis and Design of Radio SAW ID-tags

讨论了确定叉指换能器的孔径长度以及与利用串联谐振进行匹配时的方法。分析了金属化对辨识标签 (ID- tage)频率响应的影响 ,对金属化厚度和叉指换能器的周期的设计提供了依据 ,并有利于提高接收到的反射信号的信噪比 ;讨论了反射栅的反射系数大小控制以及为减小整体器件的尺寸 ,确定反射栅之间最小距离的方法 ,分析了如何有效降低插损和多次反射对 ID- tag器件影响。最后利用耦合模理论 ,获得了器件的时域响应 ,对指导器件制作具有重要意义。

The design of aperture of interdigital transducer (IDT),the impedance matching by using series resonance are discussed. In order to improve the signal-to-noise (SNR) of reflected pulses, it is necessary to take the deviation of center frequency due to mass load of metalization into consideration to determine the periodical of IDT.It is found that the bandwidth of interrogation, i.e. the bandwidth of IDT, and the velocity of SAW on the piezoelectric substrate are the key factors to reduce the dimension of ID-tag. In addition, the minimum distance between the reflectors is given. The reflectivity of reflectors for reducing insert loss and multiple transit signal is analyzed. An accurate simulation of device time domain response on two kinds of substrates based on COM theory has been developed to reduce the cost of inefficient fabrication trials and to estimate the inserting loss and multiple reflection in advance.