Design and Fabrication of a Patch Antenna for 5G Wireless Communications from a Low-Permittivity LiAlSiO-Based Ceramic.

A microwave dielectric ceramic based on lithium aluminum silicate (LiAlSiO) with ultralow permittivity was synthesized using the traditional solid-state reaction technique, and its dielectric characteristics at microwave frequencies are presented. The nominal LiAlSiO ceramic exhibited a relative permittivity of 3.95. To enhance the material properties, LiAlSiO- wt % BO microwave dielectric ceramics were fabricated by incorporating a low-melting-point sintering aid (BO), achieving a relative density exceeding 94%. The resultant ceramics exhibited a relative permittivity (ε) ranging from 3.95 to 4.42, a microwave quality factor ( × ) between 24,720 and 28,990 GHz, and a resonant frequency temperature coefficient (τ) varying from -45.9 to -20.6 ppm/°C. Additionally, the introduction of BO broadened the sintering temperature window and effectively lowered the optimal sintering temperature from 1400 to 1200 °C. Furthermore, LiAlSiO ceramics demonstrated a near-zero coefficient of thermal expansion (CTE) of 1.44 ppm/°C, which is advantageous for applications requiring high thermal stability. Based on LiAlSiO-2.0 wt % BO ceramics with ε = 4.42, × = 28,990 GHz, and τ = -20.6 ppm/°C, a microstrip patch antenna was designed and fabricated. Testing of the antenna revealed exceptional performance, including a center frequency of 4.98 GHz, a bandwidth of 280 MHz (-10 dB), and a total efficiency reaching up to 93.7%. These findings underscore the promising potential of this material in advanced microwave and wireless communication applications.