Absorbing properties and structural design of microwave absorbers based on W-type La-doped ferrite and carbon fiber composites

Sol–gel method was used to prepare W-type BaCo2Fe16O27 hexaferrite and La-doped Ba0.7La0.3Co2Fe16O27 hexaferrite. Electromagnetic parameters of the ferrites and short carbon fiber composites were measured, and reflectivity was calculated according to transmission-line theory in the range 12.4–18 GHz. The results show that reflection loss of the doped ferrite composite is higher as compared to the no doped ferrite composite. Based on the above calculation, double-layer absorbers containing La-doped ferrite and carbon fiber composites were designed, and reflectivity of the double-layer absorbers made of different thickness and composition was calculated. Finally, a kind of structural absorber having excellent absorbing properties was achieved, and the bandwidth of the reflection loss less than −10 dB can reach 5.2 GHz in the range of 12.4–18 GHz.