A series resonance circuit under sinuousoidal driving is investigated
experimentally. The inductance consists of an air coil. The capacitanc
e is made up of a Ferroelectric material that introduces its nonlinear
dielectric properties into the circuit. The dynamical system linear c
oil - nonlinear capacaitor shows an interesting behaviour. The phase p
ortrait differs in general from the ellipse of the harmonic oscillator
. For appropriate external conditions period doubling sequences, chaos
and therein enclosed periodic windows might occur. Starting From a cu
bic nonlinearity of the dielectric properties a Duffing equation is pr
oposed as a model for periodic behaviour of the series resonance circu
it. Simulations of experimentally recorded phase portraits yield good
agreement between experiment and model.