Design of monoblock dielectric filter using (PbCa)(FeNbSn)O-3 ceramics

The microwave dielectric properties of (Pb1-xCax){(Fe0.5Nb0.5)(1-y)Sn-y}O-3 ceramics (0.4 less than or equal to x less than or equal to 0.6, y = 0.05, 0.1) and design of 900 MHz band 2-pole monoblock band pass filter (BPF) ha ve been investigated to fabricate BPF. Single-phase specimens having orthor hombic perovskite structure similar to CaTiO3 could be obtained in the comp ositions of (Pb1-xCax){(Fe0.5Nb0.5)(1-y)Sn-y}O-3 (0.4 less than or equal to x less than or equal to 0.6, y = 0.05, 0.1). The substitution of Sn for (F e0.5Nb0.5) significantly increased the quality factor Q and slightly decrea sed the dielectric constant (epsilon(r)). The temperature coefficient of th e resonant frequency of 0 ppm degrees C-1 was realized at x = 0.55 and y = 0.1. The Q.f(0) value and epsilon(r) for this composition were found to be 8600 GHz and 86, respectively. A monoblock lambda/4 dielectric BPF for 900 MHz band portable telephone terminal is presented. This BPF is a kind of co mbline filter. Computer-aided design (CAD) was used in the modeling procedu re. The equivalent circuit of the monoblock BPF is represented by transmiss ion lines and lumped elements based on Z(oe) and Z(oo). A BPF model was des igned for surface mounted device (SMD) types. The simulations of the equiva lent circuit and BPF structure have been performed to optimize the filter d esign. Newly developed (Pb0.45Ca0.55){(Fe0.5Nb0.5)(0.9)Sn-0.1}O-3 dielectri c materials were used for BPF fabrication. Experimental results of the fabr icated device were in good agreement with the simulation.