Claims
- 1. An electromagnetic interference (EMI) shield comprising:
a waveguide body including an array of waveguide cells each having a contiguous inner surface; and an absorber layer covering at least a portion of each contiguous inner surface and capable of absorbing electromagnetic radiation over a select frequency range.
- 2. The shield of claim 1, wherein each waveguide cell has a polygonal cross-section.
- 3. The shield of claim 1, wherein each waveguide cell has a circular cross-section.
- 4. The shield of claim 1, wherein the polygonal cross-sectional shape is rectangular.
- 5. The shield of claim 1, wherein the absorber layer covers the entire contiguous inner surface.
- 6. The shield of claim 1, wherein the absorber layer has a thickness between about 0.025 millimeters to about 0.25 millimeters.
- 7. The shield of claim 1, wherein the absorber layer has a resistivity between about 200 Ohms/square and about 1200 Ohms/square.
- 8. The shield of claim 1, wherein the waveguide body is formed of an insulating material.
- 9. The shield of claim 8, wherein the insulating material is one selected from the group of materials consisting of: plastic, polymer, composite material, ceramic, wood and glass.
- 10. The shield of claim 1, wherein the select frequency range includes frequencies in the megahertz (MHz) range and the gigahertz (GHz) range.
- 11. The shield of claim 1, wherein the absorber layer includes an epoxy resin filled with particles having a high magnetic loss over the select frequency range.
- 12. The shield of claim 1, wherein the body is formed of metal.
- 13. An electromagnetic interference (EMI) shield, comprising:
an array of waveguide cells each having a contiguous inner surface; an absorber layer covering at least a portion of each contiguous inner surface, the absorber layer capable of absorbing electromagnetic radiation over a select frequency range.
- 14. The shield of claim 13, wherein the absorber layer entirely covers each contiguous inner surface.
- 15. The shield of claim 13, wherein the waveguide cells have a cross-sectional shape that is one of polygonal and circular.
- 16. The shield of claim 13, wherein the waveguide cells are formed from an insulator.
- 17. The shield of claim 13, wherein the absorber layer has a thickness between about 0.025 millimeters to about 0.25 millimeters.
- 18. The shield of claim 13, wherein the select frequency range includes frequencies in the megahertz (MHz) range and the gigahertz (GHz) range.
- 19. An electromagnetic interference (EMI) shield for a computer, comprising:
a metal chassis having an aperture, the chassis adapted to enclose portions of the computer that generates heat and EMI over a select frequency range; and an EMI waveguide shield fixed to the chassis and covering the aperture, the EMI waveguide shield including an array of waveguide cells each having a contiguous inner surface, and an absorber layer covering at least a portion of each contiguous inner surface, the absorber layer capable of absorbing the EMI.
- 20. The EMI shield of claim 13, wherein each waveguide cell has an associated aperture that allows heat to pass therethrough.
- 21. The EMI shield of claim 19, further comprising the computer.
- 22. The EMI shield of claim 19, wherein the waveguide shield includes a body formed from an insulator.
- 23. A method of reducing electromagnetic interference (EMI) from a computer, comprising:
enclosing portions of the computer that generate heat and EMI over a select frequency range with a metal chassis having an interior; introducing the EMI and heat to an array of waveguide cells fixed to the chassis, each waveguide cell having an aperture leading from the interior and a contiguous inner surface at least partially coated with an absorber layer that absorbs the EMI over the select frequency range; and absorbing the EMI with the absorber layer to substantially contain the EMI within the interior, while allowing the heat to pass from the interior through each aperture.
- 24. The method of claim 23, further including covering the entirety of each inner surface with the absorber layer.
- 25. The method of claim 23, including forming the absorber layer to have a thickness between about 0.025 millimeters and 0.25 millimeters.
- 26. The method of claim 23, including fixing the waveguide cells to the chassis with screws.
RELATED APPLICATIONS
[0001] This patent application is related to U.S. patent application Ser. No. ______, entitled “Method and apparatus for reducing electromagnetic leakage through chassis apertures,” filed on Jun. 26, 2001, and commonly assigned to the Assignee of the present application.