  A system model is used, describing the voltage-to-voltage transfer function
for an ultrasonic transmit-receive transducer pair based on simulations using a
finite element model for piezoelectric transducers (FEMP). The piezoelectric
ceramic elements used in this work are cylindrical Pz27 disks vibrating
radially in air at room temperature and 1 atm, over a frequency range up to 300
kHz. Comparisons are made between measurements and simulations. Effects of
uncertainties in alignment are examined, together with comparisons with prior
work.
