An electric circuit model, describing the inductive sensor of cardiac mechanical activity in its working condition, has been developed. The sensor includes a single-turn inductor coil, which is considered to be attached to the thoracic surface of a man, in front of the heart. The coil is fed by 7.7 MHz constant current and induces probing eddy currents in the body. A simple axisymmetric computer model of the thorax, formed of tightly packed circular current tubes, was created to represent the coil–patient system. With complex-valued impedivities for the body tissues, the model has been used to calculate the impedances and inductances within the system. For comparison, a fine FEM model of the same system was created and tested. Comparable results of the two different calculation methods exhibited sufficient consistence. The estimates of the parameters of the system were found and the signal production was analysed.
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