Design of wireless communication dielectric resonator antenna with adjustable rattling effect and microwave dielectric properties of melilite ALaGa3O7 (A = Ba, Sr, Ca) ceramics
Dense ALaGa 3 O 7 (A = Ba, Sr, Ca) ceramics with tetragonal melilite structure were prepared by the solid-phase method. The optimal microwave dielectric properties were obtained with ε r = 11.1 ± 0.1, 11.3 ± 0.1, 13.3 ± 0.1; Q × f = 49,400 ± 300, 31,100 ± 300, 17,100 ± 300 GHz; and τ f = −41.5 ± 1.0, −36.6 ± 1.0, −28.8 ± 1.0 ppm/°C for BaLaGa 3 O 7 , SrLaGa 3 O 7 , and CaLaGa 3 O 7 , respectively. The increased ε r and τ f while reduced Q × f in the order of BaLaGa 3 O 7 , SrLaGa 3 O 7 , and CaLaGa 3 O 7 were mainly due to the enhanced rattling effect of A-site, which resulted in large positive discrepancy Δ ε r between ε r ( Corr ) and ε r (C-M) increasing from +31.8 % to +74.7 %. The vibration modes, chemical bond characteristic and intrinsic dielectric properties were analysed by Raman, P-V-L theory, and far-infrared reflectance spectroscopy. Additionally, a dielectric resonator antenna based on BaLaGa 3 O 7 ceramic was designed with a bandwidth of 270 MHz at 6.8–7.1 GHz and a gain of 5.6 dBi at 6.9 GHz, indicating the potential candidate for dielectric resonator antennas.
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