The microwave dielectric materials of (Zn_1-xMg _x)TiNb₂O₈ for electroceramics devices applications

The microwave dielectric properties of ZnTiNb₂O₈ ( ε_r~34, Q×f ∼ 42,500GHz, τ_f ∼ -52ppm/°C) was reported by Hong et. al. To lower the dielectric loss of ZnTiNb₂O₈, we studied the systems of (Zn _1-xMg_x)TiNb₂O₈ (x=0.02-0.1) ceramics. The manner of equivalent-charge trace substitutions for Zn ²⁺-sites were replaced with Mg²⁺. In order to achieve more stability, CaTiO₃ (τ _f ∼ +800ppm/°C) was used to adjust the negative τ_f of (Zn_0.95Mg _0.05)TiNb₂O₈ (τ _f~ -58ppm/°C). A bandpass filter using coupled microstrip-line resonators have been designd for wireless LAN system such as IEEE 802.11 ( 2.4 or 5 GHz). The response of the implemented filter used 0.8(Zn_0.95Mg _0.05)TiNb₂O₈-0.2 CaTiO₃ (ε_r∼ 35.77, Q×f ∼18,000GHz, τ_f ∼ +4ppm/°C) dielectric substrates. In this paper, the bandpass filter area designed on 0.8(Zn_0.95Mg_0.05)TiNb₂O ₈-0.2 CaTiO₃ is reduced 88% than FR4 substrates and the near zero τf makes better frequency stability.