Optimization of electromagnetic matching of carbonyl iron/BaTiO3 composites for microwave absorption

Microwave absorbing materials filled with BaTiO3 and carbonyl iron (CI) particles with various weight fractions (BaTiO3/CI particles = 100/0 to 0/100) are investigated. The dielectric and magnetic properties of the absorbers can be tuned by changing the weight ratio of BaTiO3/CI particles in the frequency range of 2-18 GHz. Numerical simulations are also performed to design a single-layer and double-layer absorber. The minimum reflection loss of the composite filled with 20 wt% BaTiO3 and 60 wt% CI particles at 2.0 mm thickness can be reached to -42 dB at 4.1 GHz. With the weight ratio of CI particles in the composite increased, the microwave absorption peak shifted to the lower frequency region. By using a double-layer absorber structure, the microwave absorption performance of the absorber is enhanced. The result shows that the total thickness of the absorber can be reduced below 1.4 mm by using a matching layer filled with 50 wt% BaTiO3, and an absorption layer filled with 60 wt% BaTiO3 and 20 wt% CI particles, where as the reflection loss below -10 dB can be obtained in the frequency range of 10.8-14.8 GHz and the minimum reflection loss of -59 dB can be obtained at 12.5 GHz. (C) 2010 Elsevier B.V. All rights reserved.