The impedance concept in propagation problems and in transmission line
s is used to model an acoustic wave propagating in a quartz-crystal se
nsor loaded by a liquid medium. An impedance evaluation of the immerse
d quartz sensor is presented and different aspects are developed. Theo
retical curves drawn from this model are compared with experimental va
lues measured with a network analyser, motional elements of the equiva
lent circuit are derived for the quartz crystal with a liquid loading,
different characteristic frequencies are calculated and the correspon
ding frequency shifts due to liquid contact are compared with the Kana
zawa result.