Guoqiang He, Chao Du, Zhen‐Tao Wang, Jian Bao, Zhen Fang, Chang‐Hao Wang, Zhaochen Xi, Moustafa A. Darwish, Tao Zhou, Di‐Ming Xu, Song Xia, Yongzheng Wen, Kar Ban Tan, Di Zhou
Abstract This study pioneers the cross‐disciplinary application of garnet‐type solid‐state electrolyte Li 7 La 3 Zr 2 O 12 (LLZO) in microwave dielectric ceramics. LLZO was synthesized via solid‐state reaction, achieving optimized microwave dielectric properties at 900°C: ε r = 8.13, Q × f = 31 735 GHz, τ f = −44.3 ppm/°C. Direct cofiring experiments with Ag electrodes validated its compatibility with low‐temperature cofired ceramic (LTCC). X‐ray diffractometer (XRD)/scanning electron microscope (SEM)–energy‐dispersive X‐ray spectroscopy (EDS) confirmed interfacial stability and chemical inertness, overriding standalone thermal expansion parameter considerations. A Beidou antenna prototype on LLZO substrates demonstrated 59.2 MHz bandwidth at 1.57 GHz with 4.33 dBi gain and >97% radiation efficiency. By synergizing low‐loss microwave response with inherent Li⁺ conductivity and thermal robustness, LLZO emerges as a multifunctional platform for integrated energy‐communication systems. It enables future designs of LTCC based self‐powered modules and real‐time structural health monitoring devices. This work bridges solid‐state electrolytes and microwave ceramics, offering a paradigm for material innovation in fifth‐generation (5G)/sixth‐generation (6G) networks and intelligent electronics.