Abstract
The transmission of ultrasound through a layered structure into a liquid is controlled by the effective reflection coefficient of the layered structure. Under the conditions of resonant transmission, the effective reflection coefficient coincides with the reflection coefficient in the layer at the end of the layered structure that is in contact with the liquid. When the total number of layers increases, the resonant transmission disappears and the transmission rate of ultrasound oscillates rapidly with respect to the change of frequency. However, in the case of actual transmission measurements, this oscillation is difficult to observe. Furthermore, in the case where the substrate of the layered structure has lower acoustic impedance, the observed transmission rate has a large mismatch with the transmission rate given by the theoretical predictions.