Design of a High-Efficiency and -Gain Antenna Using Novel Low-Loss, Temperature-Stable Li2Ti1-x (Cu1/3Nb2/3)xO3 Microwave Dielectric Ceramics

Microwave dielectric ceramics are vital for filters, dielectric resonators, and dielectric antennas in the SG era. It was found that the (Cu1/3Nb2/3)(4+) substitution can effectively adjust the TCF (temperature coefficient of resonant frequency) of Li2TiO3 and simultaneously increase its Q X f (Q and f denote the quality factor and the resonant frequency, respectively) value. Notably, excellent microwave dielectric properties (epsilon(r) (permittivity) approximate to 18.3, Q X f approximate to 77,840 GHz, and TCF approximate to +9.8 ppm/degrees C) were achieved in the Li2Ti0.8(Cu1/3Nb2/3)(0.2)O-3 (LTCN0.2) ceramic sintered at 1140 degrees C. Additionally, the sintering temperature of LTCN0.2 was reduced to 860 degrees C by the addition of 3 wt % H3BO3, exhibiting superior microwave dielectric properties (epsilon(r) approximate to 21.0, Q X f approximate to 51,940 GHz, and TCF approximate to 1.4 ppm/degrees C) and being chemically compatible with silver. Moreover, LTCN0.2 + 3 wt % H3BO3 ceramics were designed as a patch antenna and a dielectric resonator antenna, both of which showed high simulated radiation efficiencies (88.4 and 93%) and gains (4.1 and 4.03 dBi) at the center frequencies (2.49 and 10.19 GHz). The LTCN0.2 + 3 wt % H3BO3 materials have promising future application for either SG mobile communication devices and/or in low-temperature co-fired ceramic technology owing to their high Q, low sintering temperature, small density, and good temperature stability.