Abstract: In SAW devices when distance x between transducers has a slight change, the ripple effected by TTE in the total amplitude response will also undergo some slight change. In this paper the relation of the ripple to x is analyzed. It is pointed out that the selection of x based on the co-linear relation ship of T TE phasor to main signal phasor is ineffective, and the more effective selection should be based on the orthogonality.