| 摘要 |
PROBLEM TO BE SOLVED: To ensure a return loss more than a specified value in an electromagnetic wave absorber, which is formed into a sheet shape, by a method wherein the volume filling rate of a soft magnetic metal powder of an aspect ratio lower than a specified value to a matrix, the thickness of a sheet and a frequency region are respectively selected in a specified range to select the volume filling rate of the metal powder, the thickness of the sheet and the frequency region according to a frequency region to contrive to make the peak of the return loss position. SOLUTION: Powder of an aspect ratio lower than 2 is used as soft magnetic metal powder, such as sendust powder, Permalloy powder, Fe-Cr alloy powder, Fe-Cr-Al alloy powder and Fe-Cr-Si alloy powder, which is used for forming an electromagnetic wave absorber. The volume filling rate of the soft magnetic metal powder to a matrix, the thickness of a sheet and a frequency region are respectively selected within the range of 18 to 32%, within the range of 1.3 to 3.5 mm and within the range of 6 to 20 GHz to select the volume filling rate and the thickness according to a frequency region to contrive to make the peak of a return loss position. Thereby, an electromagnetic wave absorbing sheet ensuring an attenuation more than 20 dB and of 22 to 25 dB as the value of the return loss can be obtained. |
