Third Harmonic Distortion of Dielectric Resonator Materials

Microwave dielectric materials must have a low third harmonic distortion when they are used for high-power applications. This is because the third harmonic distortion produces a third-order intermodulation distortion which generates interference between signals. In this paper, the measurement results of the third harmonic distortion levels for three types of dielectric resonator materials, (Zr, Sn)TiO4, MgTiO3-CaTiO3 and BaO-PbO-Nd2O3-TiO2, are reported and the equations derived to combine the distortion level and the fourth anharmonic term in the crystal's Hamiltonian. The measured distortion levels have a strong correlation with dielectric loss tangents of the materials. This relationship is also explained in connection with the anharmonic terms in the crystal's Hamiltonian.