Ferroelectric Harmonic Generator and the Large-Signal Microwave Characteristics of a Ferroelectric Ceramic

Publisher Website
Google Scholar
Abstract
At microwave frequencies, ferroelectric ceramics behave as nonlinear dielectrics and exhibit large signal scalar nonlinear characteristics in both the dielectric constant and the rf conductivity. The nonlinear behavior of a ceramic of 73% BaTiO3‐27% SrTiO3 has been used to construct a harmonic generator operating from 3 kMc to 9 kMc. An efficiency of 8.5% for a peak input power of 2200 w was attained. In addition, a new measurement technique has been developed for measuring the large signal properties of this ceramic as well as for other nonlinear materials. This technique makes explicit use of the anharmonic response of a resonant system that contains a nonlinear element. The analysis of both the harmonic generator and the nonlinear resonant system takes into account nonlinear reactance as well as nonlinear resistance. For temperatures about 30°C above the Curie temperature (the Curie temperature for the ceramic composed of 73% BaTiO3‐27% SrTiO3 is approximately 20°C) the large signal dielectric constant and rf conductivity were found to be given by the expressions ε′(|E|)=ε0[2200−7.5×10−11|E |2] farad/m, and σ(|E|) =ωε0[160+29×10−12|E|2] mhos/m, where |E| is in volts per meter. These results were obtained at 3 kMc and are valid up to field strengths of 20 kv/cm.

This publication has 8 references indexed in Scilit: