Hashimoto K, Yamaguchi M, Kovacs G, Wagner K C, Ruile W, Weigel R
Department of Electronics and Mechanical Engineering, Faculty of Engineering, Chiba University, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2001 Sep;48(5):1419-25. doi: 10.1109/58.949752.
This paper investigates the effects of bulk acoustic wave (BAW) radiation on the admittance of interdigital transducers (IDTs) with significant internal reflections of shear horizontal (SH) type leaky surface acoustic waves (SAWs) on 42 degrees YX-LiTaO3 (42-LT). Theoretical analysis is made by using the discrete Green function theory, and synchronous one-port resonators are analyzed. It is shown that the BAW radiation significantly affects the IDT characteristics even for resonators; under certain circumstances, BAWs launched from an IDT are converted into SH-type SAWs by the strong internal reflections, and they interact with the BAWs radiated by the IDT. Then, the net amount of the radiated BAW power is highly dependent upon the number of IDT finger pairs. For the precise simulation of devices based on the SH-type SAWs with strong internal reflections, the BAW radiation should carefully be taken into consideration. If the BAW radiation is ignored, the radiated power of the SH-type SAWs may seem to be negative above the BAW cut-off frequency.
本文研究了体声波（BAW）辐射对叉指换能器（IDT）导纳的影响，该叉指换能器在42°YX - 钽酸锂（42 - LT）上存在显著的水平剪切（SH）型漏表面声波（SAW）内部反射。采用离散格林函数理论进行理论分析，并对同步单端口谐振器进行了分析。结果表明，即使对于谐振器，BAW辐射也会显著影响IDT特性；在某些情况下，由IDT发射的BAW会通过强烈的内部反射转换为SH型SAW，并且它们会与IDT辐射的BAW相互作用。然后，辐射的BAW功率净值高度依赖于IDT指对数。对于基于具有强烈内部反射的SH型SAW的器件进行精确模拟时，应仔细考虑BAW辐射。如果忽略BAW辐射，在BAW截止频率以上，SH型SAW的辐射功率可能会显得为负。
