Lattice dynamics, chemical bonding and dielectric properties of low-permittivity Ba2MgGe2O7 microwave ceramics and simulation of 5G/6G microstrip patch antenna

Ba 2 MgGe 2 O 7 (BMG) ceramics were prepared via solid-state reaction and sintered at 1225-1325 °C. Rietveld refinement of X-ray diffraction data confirmed a phase-pure tetragonal structure (space group P 21m) across the entire investigated sintering range. The sample sintered at 1275 °C attained 95.2% relative density and exhibited the best microwave dielectric properties: ε r = 9.01, Q × f = 57,805 GHz ( f = 13.91 GHz), and τ f = –40.84×10 −6 °C −1 . Seventeen infrared-active modes were identified through Raman and far-infrared reflectance spectroscopy. FPSQ modeling, combined with first-principles phonon calculations, revealed that low-frequency Ba–O and Mg–O vibrational modes dominate the intrinsic dielectric constant. P–V–L bond analysis further established that Ge–O bond ionicity is correlated with ε r , while lattice energy is closely associated with Q × f , providing a quantitative framework that links local bonding environment to dielectric loss. Notably, the Q × f value obtained here nearly triples that reported previously for the same composition. A simulated 4.5 GHz microstrip patch antenna based on the BMG ceramic achieved an S 11 of –27.90 dB and a peak realized gain of 6.26 dBi, demonstrating the potential of the material for sub-6 GHz 5G antenna applications.