Achieving ultrahigh Q Mg₃(PO₄)₂ solid solution through structural optimization for broadband antenna applications

The rapid advancement of high‐frequency wireless communication systems has significantly increased the demand for microwave dielectric ceramics with low ε r and ultra‐high Q · f . To address the demand, a novel solid solution ceramic was developed by substituting Zn 2+ for Mg 2+ in β ‐Mg 3 (PO 4 ) 2 . The incorporation of Zn 2+ effectively mitigated intergranular cracking and significantly enhanced ceramic densification. Therefore, the (Mg 1− x Zn x ) 3 (PO 4 ) 2 ceramics exhibit optimal microwave dielectric properties at x = 0.3, with ε r ≈ 5, Q · f = 138 084 GHz, and τ f = −33.74 ppm/°C, achieving a substantial enhancement in Q · f compared with the matrix. To explore the intrinsic mechanism enhancing the Q · f , the structural evolution was conducted. Refinement analysis indicated that Zn 2+ incorporation led to an expansion in unit cell volume. Based on this, a structure–properties relationship was established using the P–V–L theory, which revealed that the observed improvement in Q · f originates primarily from enhanced bond covalency and lattice energy. Furthermore, terahertz time‐domain spectroscopy confirmed the excellent sub‐millimeter wave performances ( ε r = 5.15, Q · f = 161 205 GHz). Leveraging these outstanding properties, a broadband cylindrical DRA was designed and fabricated, achieving a 30.2% bandwidth and a peak gain of 7.22 dBi, demonstrating significant potential for radar and satellite communication applications.