LiGaSiO4: An ultra-low permittivity dielectric material enabling application in patch antenna

A low permittivity microwave dielectric ceramic, Li-containing silicate (LiGaSiO 4 ), was synthesized using the standard solid-state reaction method. The nominal LiGaSiO 4 ceramic exhibited a relative permittivity of approximately 4.4. The effects of nonstoichiometric Li on the microstructure, sintering behavior, and microwave dielectric properties of LiGaSiO 4 were comprehensively investigated. Excess Li content (6 mol%) significantly improved the relative density (96.1 %) and microwave dielectric properties ( ε r ∼5.34, Q  ×  f ∼55,600 GHz, and τ f  ∼ -48.6 ppm/°C), while reducing the optimum sintering temperature from 1070 °C to ∼1010 °C. Additionally, the incorporation of 2 wt% LiF further reduced densification temperature (∼940 °C). The regulation of the τ f was achieved through the addition of CaTiO 3 ceramic, and a patch antenna was designed and fabricated using a modified Li 1.06 GaSiO 4 -LiF-CaTiO 3 composite ceramic. The resulting patch antenna resonates at 5.87 GHz with an impressive bandwidth of 83.1 MHz, while both simulated and measured results demonstrate excellent agreement.