US 3219747 A
Description (OCR text may contain errors)
Nov. 23, 1965 J, c s 3,219,747
SHIELDING ARRANGEMENT WITH WAVE GUIDE BELOW CUTOFF Filed Feb. 8, 1963 N .OC 3
L w E050 w 33% v QE 7 w m N mdE ii gg N James H. M Adoms,
T J m 3,219,747 SHIELDING ARRANGEMENT WITH WAVE GUIDE BELOW CUTOFF James H. McAdams, Huntsville, Aia, assignor to the United States of America as represented by the Secretary of the Army Filed Feb. 8, 1963, Ser. No. 257,823 2 Ciaims. (Ci. 174-35) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured an used by or for the Government for governmental purposes without the payment of any royalty thereon.
This invention relates to a shielding device and more particularly to a device for reducing the transfer of electromagnetic or electrostatic energy through an opening.
Shielding devices for covering openings in the past have been in the form of conventional door structures and have not been sufiiciently effective since these doors have failed to provide a complete shield for the opening. The present invention overcomes this failure by providing a device having an overlapping relationship when used with an element requiring a shielding device.
The use of this shielding device with an opening in a housing wall has been found to act as a Faraday shield for reducing the transfer of electrostatic energy therethrough. The covering device also reduces the transfer of electromagnetic and electrostatic energy by providing a completion of interrupted magnetic and electric paths. The passage of electromagnetic waves is also reduced by making the overlapping portions of the cover and housing wall form waveguide below cutoff type devices.
It is, therefore, an object of this invention to provide an improved shielding device for reducing the transfer of electromagnetic and electrostatic energy from a first volume to a second volume.
Another object of this invention is to provide a shielding device wherein intimate contact between a cover and a housing wall is not required.
A further object of the invention is to reduce the importance of mechanical alignment and mating between a housing and a cover device.
The foregoing and other objects and advantages of this invention will become more fully apparent from the following detailed description of this invention and from the accompanying drawings, in which:
FIGURE 1 is a front view of a housing incorporating one embodiment of the invention.
FIGURE 2 is a sectional view along the line 2-2 of FIGURE 1, showing the shielding device spaced from the housing.
FIGURE 3 is a partial sectional view of the invention utilizing a modified shielding device.
FIGURE 4 is a partial sectional view illustrating a modified shielding device.
FIGURE 5 is a partial sectional view illustrating a modified shielding device.
FIGURE 6 is a partial sectional view illustrating a further modification of the shielding device.
FIGURE 7 is a partial sectional view of the invention showing a further modification of the shielding device.
According to a preferred embodiment of the invention a housing 2 of electromagnetic opaque material has an aperture 4 formed therein. To prevent transmission of electromagnetic energy through the aperture there is provided a door or cover 6 overlapping and completely covering the aperture. Although the cover and aperture are shown, in FIGURE 1, as having a rectangular shape 'nited States Patent ice it is to be understood that this invention lends itself to covers having many configurations. The cover may be supported in any conventional manner such as pivoted hinges, clamps, etc., which permit the initial opening and final closing of the cover to be perpendicular to the enclosure wall. This action reduces sliding or scraping actions on a radio frequency barrier, gasket 10, shown in FIGURES 3-7, which may tend to destroy the barrier material. The barrier material is not required but may be used to improve the shielding efficiency of the device.
The cover and wall structure of the invention may take many forms, for example, in FIGURE 3 is shown a modification wherein the cover has a protruding portion 8 extending toward the housing wall. The embodiment of FIGURE 4 may be constructed so that the protruding portion 8 contacts the wall or the portion 12 may contact the cover. Either construction will yield a Waveguide below cutoff cavity to further attenuate the electromagnetic energy at certain portions of the electromagnetic spectrum.
Other modifications include such constructions as a groove 14 formed in the wall of housing, FIGURE 5, or channels formed by protruding portions 16, 18 and 20, 22 (illustrated in FIGURES 6 and 7).
While the invention has been described with reference to preferred embodiments thereof, it will be apparent that various modifications and other embodiments thereof will occur to those skilled in the art within the scope of the invention. Accordingly, I desire the scope of my invention to be limited only by the appended claims.
l. A radio frequency shielding arrangement comprising: a wall member having an aperture therein, and a removable cover adjacent said aperture completely covering said aperture and direct current isolated from said wall, said wall including first and second protruding portions surrounding said aperture and extending toward said cover and forming a channel therebetween, said cover including first and second protruding portions extending toward said wall and forming a channel therebetween wherein the first protruding portion of said wall extends into the channel between the first and second protruding portions of said cover, and the second protruding portion of said cover extends into the channel between the first and second protruding portions of said wall.
2. A radio frequency shielding arrangement as set forth in claim 1 wherein said protruding portions form a waveguide below cutoff when said cover is in place.
References Cited by the Examiner UNITED STATES PATENTS 2,500,676 3/1950 Hall et al. 219-1055 2,527,908 10/ 1950 Blitz 174-35 X FOREIGN PATENTS 215,571 6/1961 Australia. 936,639 12/1955 Germany.
OTHER REFERENCES Metex: Suppressing Radio Interference With Metex Shielding Products, published by Metal Textile Corporation, Electronic Division, Roselle, N.J., (pages 12 and 13 relied on).
JOHN F. BURNS, Primary Examiner.
JOHN P. WILDMAN, Examiner.