Wide temperature stable Ba(Mg Ta2/3)O3 microwave dielectric ceramics with ultra-high-Q applied for 5G dielectric filter

Abstract Microwave dielectric ceramics are expected to yield unusually brilliant results in 5G (5th generation mobile networks) dielectric filter applications. In this paper, high-performance microwave dielectric ceramics with composite perovskite structure were synthesized by non-stoichiometric introduction of Mg2+ in Ba(Mg1/3Ta2/3)O3 (BMT). Typically, all samples synthesized exhibit predominant resonance frequency stability (resonance frequency shift below 1MHz) from -55°C to 85°C. Ultimately, the best microwave dielectric properties of er~24.662, Q × f~248,414GHz, τf~0.55ppm/°C were obtained by Ba(Mg0.327Ta2/3)O3 ceramics sintered at 1640°C for 12h and annealed at 1500°C for 12h, and its Q × f value was about 12% higher than that of pure BMT. A cross-coupling hairpin microstrip line dielectric filter was designed and fabricated using the dielectric substrate made of Ba(Mg0.327Ta2/3)O3 ceramics. The filter resonated at about 3.5GHz (one of 5G licensed bands) with a bandwidth ~560 MHz at −0.56dB insertion loss (S21). The introduction of Ba(Mg0.327Ta2/3)O3 dielectric substrate not only improves the performance of the filter, but also greatly reduces its size (14 × 8 × 0.5mm), which suggest that the Ba(Mg0.327Ta2/3)O3 ceramics may have great application prospects in 5G dielectric filters.