High‐Frequency Magnetic Properties of Cu–Zn 18H Hexaferrites for Miniaturized Antenna Application in the GHz Band

Rapid development of 5 G technology necessitates magnetodielectric materials with high permeability and low loss in the sub‐6 GHz band. Here, unique magnetodielectric materials with a hexagonal structure are reported, named Cu–Zn 18 H hexaferrites (Ba 5 Cu 2‐x Zn x Ti 3 Fe 12 O 31 ). Substitution of Cu 2+ with Zn 2+ in these materials can effectively tailor the permeability and resonance frequency of the materials through domain wall motion and spin rotation, respectively. The Cu–Zn 18 H hexaferrite with x = 0.4 has a low magnetic loss (= 0.026) and a high figure of merit ( 142 GHz) at an operating frequency of 3 GHz, outperforming traditional microwave ferrites. When employed as the substrate of a patch antenna at 3.6 GHz, the Cu–Zn 18 H hexaferrite offers substantial advantages over conventional dielectric materials by achieving smaller dimensions (89.8%) and broader bandwidths. These results reveal the considerable potential of the Cu–Zn 18 H hexaferrite for 5 G communication applications.