Radio wave absorption sheet for millimeter wave band and millimeter wave radio wave absorption method

摘要

Provided is a sheet-like radio wave absorber that has excellent radio wave absorption performance at a frequency in the millimeter wave band, and is lightweight and excellent in flexibility. A radio wave reflection layer (A), a radio wave absorption layer (B) arranged in parallel with the upper part of the layer (A), and a protective layer (C) arranged in parallel with the upper part of the layer (B) A wave absorbing sheet for millimeter wave band, wherein the real part of the relative permittivity of the layer (B) at a frequency of 79 GHz is 10 to 20, the absolute value of the imaginary part is 4 to 10, and the layer (B) The absolute value of the imaginary part / real part of the relative permittivity is in the range of 0.30 to 0.60, and the real number of the relative permittivity of the layer (C) at a frequency of 79 GHz is 200 to 400 μm. Part is 1.5 to 8.0, the absolute value of the imaginary part is less than 1.0, the film thickness is 50 to 200 μm, the light reflectance at an incident angle of 60 ° is 50% or more, and the incident angle is 20 Millimeter wave band wave absorbing sheet having a light reflectance of 25% or more, and a millimeter using the wave absorbing sheet. Wave absorption method band, and method for preventing interference of installing the electric wave absorber sheet.