| 摘要 |
PROBLEM TO BE SOLVED: To provide an electromagnetic wave absorber used in a submillimeter (20-30 GHz) to millimeter (30-100 GHz) frequency region which is made by dispersing soft magnetic metal powder in a rubber or plastic matrix and then forming the material into a sheet and which has the absorption peak at a specified frequency. SOLUTION: The electromagnetic wave absorber is made by dispersing the specified soft magnetic metal powder into the specified matrix material at various filling rates. The electromagnetic wave absorber is measured at each filling rate for the magnetic permeability (μ) and the permittivity (ε) at the frequency where the electromagnetic wave absorption peak is to be located. Based on the obtained data, the electromagnetic wave absorber is designed in combination of the thickness and the return loss. The return loss is expressed by the following expression: RL=20LogΓ, where Γ(reflection coefficient)=(Zin-Z0)/(Zin+Z0), Zin=Z0√ (μ/ε)×tanh[j(2πd/λ)×(√ (με))], Z0 = characteristic impedance in the air, d = thickness of the absorber, λ = the filling rate making the wavelength the maximum. |
