Temperature-stable Li4Ti3O8 composite microwave dielectric ceramics and their applications in dielectric resonator antennas

Li4Ti3O8 composite ceramics were synthesized via the solid-state reaction method. The microwave dielectric properties of these ceramics and their potential applications in dielectric resonator antennas were analyzed in detail. The relative density predominantly influenced the ϵr and Q × f of Li4Ti3O8 ceramics. The optimal microwave dielectric properties (ϵr = 26.7, Q × f = 66 020 GHz, and τf = −3.3 ppm °C−1) were achieved through sintering at 1160 °C. There is a minimal change of ϵr of Li4Ti3O8 ceramics over a wide temperature range (−100 °C to 100 °C), indicating excellent stability. A cylindrical DRA prototype fabricated from Li4Ti3O8 resonates at 6.45 GHz (S11 < −10 dB) with a maximum radiation efficiency exceeding 92.6%. In conclusion, the Li4Ti3O8 material is a viable candidate for 5/6G applications owing to its low loss and temperature stability advantages.