Low-loss Z-type hexaferrite with Sr-substitution for microwave antenna miniaturization

Magnetic and dielectric properties of conventional ceramics processed 3 Ba
_(1-x)
Sr
_x
O · 2 CoO · 10.4 Fe
₂
O
₃
(x = 0.1 ~ 0.8) hexaferrite were investigated for microwave antenna miniaturization. Sr substitution was used to modulate the high frequency properties of Co
₂
Z materials in this paper. The properties of the materials were characterized by SEM, XRD, Vector Network Analyzer, and so on. All samples showed that Z-phase was the main phase with traces of M-phases and Y-phases and the resonance frequencies were all above 2GHz. 3 Ba
_(1-x)
Sr
_x
O · 2 CoO · 10.4 Fe
₂
O
₃
samples sintered at 1050°C had a loss tanδ
_μ
= 0.05 with the permeability of 7.5 at 1GHz and the miniaturization factor n reached a value up to 11.2 under 2GHz. It was found that Co
₂
Z samples with Sr substitution showed a better low-loss property for microwave antenna application than Sr-free samples, which was benefit for microwave antenna miniaturization and performance improvement.