Electromagnetic wave absorber and electronic device

1. An electromagnetic wave absorber comprising:

a first layer having a first enclosing layer that encloses an electromagnetic wave radiator from all directions, and a first metal film formed over the first enclosing layer,

wherein the first metal film has one of a shape having a surface roughness, an uneven shape having a concave portion and a convex portion, and a gentle sloping shape, and

a slit is formed as an opening in the first metal film.

2. The electromagnetic wave absorber according to claim 1 , wherein the first layer includes a second enclosing layer formed over an opposite surface of the first metal film other than a surface of the first metal film where the first enclosing layer is formed.

3. The electromagnetic wave absorber according to claim 1 , further comprising: an electronic circuit mounted over the first metal film.

4. The electromagnetic wave absorber according to claim 1 , wherein the first metal film is electrically coupled to the electromagnetic wave radiator.

5. The electromagnetic wave absorber according to claim 1 , wherein the first metal film has a coiled pattern that is wound around the electromagnetic wave radiator.

6. The electromagnetic wave absorber according to claim 1 , wherein the first enclosing layer contains resin.

7. The electromagnetic wave absorber according to claim 1 , wherein the first enclosing layer contains a carbon material.

8. The electromagnetic wave absorber according to claim 1 , wherein a thickness of the first enclosing layer is (2m−1)/4 times (m is a natural number) a wavelength of electromagnetic waves propagating inside the first enclosing layer.

9. The electromagnetic wave absorber according to claim 1 , further comprising: a second layer having a third enclosing layer that encloses the first layer, and a second metal film formed on the third enclosing layer.

10. The electromagnetic wave absorber according to claim 1 , wherein one or more resistance elements is provided over the slit.

11. An electronic device comprising:

an electromagnetic wave radiator configured to radiate electromagnetic waves; and

an electromagnetic wave absorber configured to enclose the electromagnetic wave radiator;

wherein the electromagnetic wave absorber includes a first layer having a first enclosing layer that encloses the electromagnetic wave radiator from all directions, and a first metal film formed over a surface of the first enclosing layer,

the first metal film has one of a shape having a surface roughness, an uneven shape having a concave portion and a convex portion, and a gentle sloping shape, and

a slit is formed as an opening in the first metal film.

12. The electronic device according to claim 11 , wherein the first metal film has a lower resistivity than a resistivity of ferrite.

13. The electronic device according to claim 11 , wherein the first metal film has a lower resistivity than a resistivity of ferrite.

14. The electronic device according to claim 11 , wherein one or more resistance elements is provided over the slit.