The parametric effects in the microwave Read avalanche diode are studied using a simplified one-dimensional model. The signals of frequencies ω
1and ω
2interact with each via the pumping wave of frequency

, through the nonlinearity in avalanche. This paper shows the range in which the microwave Read avalanche diode has the parametric negative resistance, some typical values of the impedance matrix elements of the microwave Read avalanche diode, and shows that the small-signal impedance locus of the microwave Read avalanche diode on Smith chart coincides approximately with Kita\´s experimental results.