[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 Y=3:Q%X  
Extraction of the SAW Attenuation Parameter @Kri)U i
 
in Periodic Reflecting Gratings mfu>j,7l  
Saku Lehtonen, Victor P. Plessky, Senior Member, IEEE, Clinton S. Hartmann, Member, IEEE, and 5G8`zy  
Martti M. Salomaa, Member, IEEE +NRn>1]  
Abstract—In this paper, the extraction of the couplingof- 06bl$%  
modes (COM) model attenuation parameter 􀀀 in a finite ;K?fAspSH  
grating is considered. We use test structures comprising t/cjz/]  
identical transmitting and receiving transducers and a grating FAu G`zu  
centered in the acoustic channel along the propagation ?U0iHg{  
direction of the surface acoustic wave (SAW). The extraction H[%Fo  
procedure proposed is based on studying the magnitude zO>N3pMv  
of the ratio of the reflection and transmission coefficients /p') u3  
of the grating, R/T, obtained through time gating fSp(}'m2L  
from the S parameter measurements of the test devices. In `+b>@2D_  
particular, we found that the level of the notches of R/T directly lv}U-vK  
depends on the attenuation of SAW in the grating. A EmNB}\IYU  
simple closed-form expression for the attenuation normalized ;% *e}w0  
to the grating length, 􀀀0, depending on the characteristics V|NWJ7  
of jRTj, is gi .. 4ei .-  
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