TRANSMISSION-LINE METHOD FOR THE MEASUREMENT OF THE ACOUSTIC NONLINEARITY PARAMETER IN BIOLOGICAL LIQUIDS AT VERY HIGH-FREQUENCIES

Nonlinear wave propagation in a system consisting of a liquid specimen held between two SiO2 buffer rods is studied as a new method of deter mining the acoustic nonlinearity parameter of liquids at very high fre quencies. Since the sign of the nonlinearity parameter of SiO2 is oppo site that for liquids, the system can be viewed as a transmission line containing regions of both positive and negative nonlinearity. The no nlinear characterization curve is employed in which the second harmoni c component output of the receiving transducer is plotted as a functio n of propagation distance in liquids between the two SiO2 buffer rods. The nonlinearity parameter is determined by measuring the dip positio n at which the transducer output becomes zero in the curve. Measuremen ts are reported for water and aqueous solutions of dextrose and dextra n in the fundamental frequency range 100-200 MHz. (C) 1997 Acoustical Society of America.