漏波和高次谐波的耦合模式模型公式的严格推导  

A Rigorous Theoretical Derivation of the COM Formula for the Leaky Waves and Harmonic Waves

作　　者：童健[1] 林基明[1] 陈慧[1] 王宁[1] 水永安[1] 

机构地区：[1]南京大学声学所

出　　处：《压电与声光》2001年第5期330-332,408,共4页Piezoelectrics & Acoustooptics

基　　金：国家自然科学基金资助项目 ( 10 0 740 34)

摘　　要：表面波理论中 ,广泛采用耦合模式 (COM)模型来描述指间多次反射效应。现有 COM模型是建立在一个简化基础模型上的 ,其简化包括 :1)耦合反射系数κ和换能系数α均假定为常数以保证偏微分方程有解 ,而实际上它们是空间位置的函数 ;2 )传播常数 k假设为实数 ,但对漏表面波 ,k应为复数。为此 ,本文严格推导了 COM理论公式 ,得到了耦合反射系数的谐波级数展开 ,由此可以重建指条反射系数的空间分布 ,同时将周期栅格阵下的COM方程推广到波传播有体波泄漏的情况 ,即包括漏波和 Rayleigh波高次谐波的情形。最后给出一个实例 ,对一种单向单相换能器的基本单元计算了其耦合反射系数和换能系数 。Coupling of modes(COM)model has been widely used in SAW field to describe the electrode multi reflection effects The accepted COM model was derived in a simplified fashion The simplification lies on:1)It was assumed that the coupling reflection coefficient κ and the transduction coefficient α were constants so that the partial differential equation is solvable and in fact they are functions of position 2)It was assumed that the propagation constant k is a real variable in derivation and it was applied to the leaky wave situation as well,in which k is a complex number actually In this paper a complete derivation of COM model is given A series of harmonic expending coefficients of the coupling reflection are introduced instead of one constant and the reflection distribution of electrodes could be reformed by them The COM equations are generalized to the case of leaky wave or high order harmonic Reyleigh wave under the gratings Finally,as an example,the coupling reflection coefficient and the transduction cofficient of a component single phase unidirectional transducers is calculated,the result verfied the derivation in this paper.

关 键 词：耦合模式模型 漏波 谐波 表面波 

分 类 号：TN011[电子电信—物理电子学]