The microwave dielectric properties of ZnTiNb2O8 ( εr~34, Q×f ∼ 42,500GHz, τf ∼ -52ppm/°C) was reported by Hong et. al. To lower the dielectric loss of ZnTiNb2O8, we studied the systems of (Zn 1-xMgx)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 τf of (Zn0.95Mg 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(Zn0.95Mg 0.05)TiNb2O8-0.2 CaTiO3 (εr∼ 35.77, Q×f ∼18,000GHz, τf ∼ +4ppm/°C) dielectric substrates. In this paper, the bandpass filter area designed on 0.8(Zn0.95Mg0.05)TiNb2O 8-0.2 CaTiO3 is reduced 88% than FR4 substrates and the near zero τf makes better frequency stability.