A method for analyzing the microwave absorption properties of magnetic materials

Based on transmission line theory, a complex thickness is introduced to analyze the electromagnetic wave absorption properties of materials with high magnetic loss and low dielectric loss. At each frequency the real part of the complex thickness denotes the thickness of the absorber to reach maximum absorption, while the absolute value of the imaginary part of the normalized complex thickness represents the degree of impedance mismatch between the material and free space. Using this method, the intensity of the reflection loss and the corresponding material thickness can be well predicted and understood. This method describes well the microwave absorption behaviors of PANI/α-Fe and PANI/CIP/Fe3O4 composites. It is found that the electromagnetic energy loss in the material, as well as the interference cancellation of the reflected waves at the air-material interface, contributes to the global minimum of reflection loss for the two composites.

► A complex thickness is put forward based on transmission line theory.
► The imaginary part denotes the impedance mismatch of the material.
► This method enables efficient capture of the wave-absorbing behaviors of materials.