Electromagnetic Wave Absorbers (Detailed Theories and Applications) || Measurement Methods on <scp>EM</scp> ‐Wave Absorbers

摘要： In order to deepen our knowledge of the electromagnetic (EM)-wave absorber design, it becomes important to accurately know the material characteristics and the characteristics of the absorber itself. In this chapter, after describing the measurement methods of material constants, the measurement methods of EM-wave absorber characteristics are described. In particular, we intend here to explain in detail the measurement methods of material constants, including conventional methods together with analytical methods. In Section 7.1, as the methods of measuring the material constants for wave-absorbing materials, the methods of using a rectangle waveguide, coaxial waveguide, and microwave resonators are described. First, measurement methods based on the standing-wave method using the rectangular waveguide and coaxial waveguide are studied. Second, in the microwave resonator methods for cylindrical cavities, the measurement methods of dielectric constant and conductivity in the lossless case, complex permittivity, and complex permeability are investigated theoretically. In Section 7.2, as a method for measuring the EM-wave absorber characteristics, the method of TEM mode transmission lines such as coaxial waveguides, strip lines, and TEM cells are examined first. Then, the waveguide method, as a special case, is described, along with space standing-wave methods.