Dielectric nonlinearity of the displacive ferroelectrics at UHF

Consideration is given for the dielectric nonlinearity of ferroelectrics both in a strong static field with respect to the weak UHF field and in the strong UHF field. The dynamic theory of a soft mode is used as a basis for description of the phenomena. The parametric process in the strong UHF field is discussed. The applications in microwave engineering are expected.