Table 2.

Properties and coefficients of the backing layers calculated relatives to the 1–3 piezocomposite element.

Transducer	Backing Layer	Propagation Velocity	Acoustical Impedance	Tp	Rp	Ti	Ri
T1	Air	340 m/s	≈400 rayl	≈0	−1	0	1
T2	Resin AW106/Hardener HV953U	2300 m/s	2.5 Mrayl	0.28	−0.72	0.49	0.51