[其它]Extraction of the SAW Attenuation Parameter in Periodic Reflecting Gratings

ieee transactions on ultrasonics, ferroelectrics, and frequency control, vol. 52, no. 1, january 2005 111
9;yn}\N `  
Extraction of the SAW Attenuation Parameter V8=Y@T,  
in Periodic Reflecting Gratings /S:F)MO9  
Saku Lehtonen, Victor P. Plessky, Senior Member, IEEE, Clinton S. Hartmann, Member, IEEE, and ( *G\g=D  
Martti M. Salomaa, Member, IEEE `P
Xz  
Abstract—In this paper, the extraction of the couplingof- bbxLBD'  
modes (COM) model attenuation parameter 􀀀 in a finite PiFD^w  
grating is considered. We use test structures comprising c62=*] ,  
identical transmitting and receiving transducers and a grating 4E44Hzs  
centered in the acoustic channel along the propagation "i:T+#i({O  
direction of the surface acoustic wave (SAW). The extraction s=?aox7  
procedure proposed is based on studying the magnitude $ _8g8r}  
of the ratio of the reflection and transmission coefficients JcJmds  
of the grating, R/T, obtained through time gating _wb0'xoK"  
from the S parameter measurements of the test devices. In wPbkUVO  
particular, we found that the level of the notches of R/T directly [6jbg
W~E  
depends on the attenuation of SAW in the grating. A =O|c-k,f@  
simple closed-form expression for the attenuation normalized .@iFa3  
to the grating length, 􀀀0, depending on the characteristics \qsw"B*tv`  
of jRTj, is gi .. Es5  
m?s}QGSka  

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