Abstract:
Novel assemblies for use in conjunction with RF shielded enclosures and the like include one or more RF power and signal filters connectibly inserted, attached to, or otherwise made a part of optimized cavities or receptacles formed within an optimized frame of the assembly. The use of optimized cavities or receptacles greatly reduces the number of exterior fasteners needed to connect filters to the assembly or the assembly to an enclosure which, in turn, reduces leakage. The optimized cavities or receptacles may be arranged in a compact manner in order to make optimum use of the available space on an optimized frame of the assembly.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of, and claims priority from, U.S. patent application Ser. No. 12/703,712 filed Feb. 10, 2010 (the &#39;712 Application). The &#39;712 Application claims priority from U.S. Provisional Application No. 61/150,989 filed Feb. 9, 2009 (the &#39;989 Application). The instant application incorporates by reference herein as if set forth in full herein the disclosures of both the &#39;712 and &#39;989 Applications. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Keeping communications secret from an adversary or competitor has long been the challenge of the military, agencies of the federal government as well companies that are targets of corporate espionage. The challenge becomes even more difficult when communications are made from locations that do not have structures that have been built to prevent eavesdropping and the like, such as when a member of the presidential cabinet, foreign service or military travels to a foreign country, works in an embassy built by some other country or travels to a locale within the United States that is not considered secure from a communications point of view. 
         [0003]    One method of ensuring that communications remain secure in the situations described above, and others, is to put communications equipment inside a portable, shielded enclosure. One example is a tent made from a special fabric that prevents eavesdropping and leakage of communication signals (e.g., radio frequency, “RF”, signals). Whenever communications need to be secure, an individual walks into the enclosure, closes the enclosure and uses the communications equipment installed within the enclosure to send and receive communications. 
         [0004]    Though such enclosures make it more difficult to conduct eavesdropping and reduce potential leakage of signals, they are not fool proof. For example, though the equipment inside the enclosure may be secure such equipment must receive sufficient power from the outside. Further, if communications are conducted over wired links such wires must be connected through the walls or “skin” (i.e., surfaces) of the enclosure. 
         [0005]    Existing enclosures include an access panel or opening through which power and signal wires may pass. Because eavesdropping and leakage is possible through such an opening and over such wires a specially designed filter assembly is used. The assembly is designed to be attached to, and fit into, the opening. Once installed in the opening the signal and power wires from the outside are connected to the exterior side of the assembly while interior wires leading to communications equipment and the like are connected to the interior side of the assembly. Existing assemblies include a specially designed and machined metal frame. Attached to the frame are specially designed electronic and electrical filters. Once attached to the frame, the filters are then placed between the exterior and interior wires to ensure that unwanted communication or power signals are not allowed to pass into the enclosure and unsecure communication signals are not allowed to escape. 
         [0006]    Existing assemblies require the use of many fasteners, such as screws and bolts to fasten the filters to the metal frame.  FIG. 1  depicts an example of an existing assembly  1 . As shown, sixteen screws  2  must be used to install a flange  3  to the frame  4 . The flange  3  is needed to make sure a power filter  5  is physically connected to the assembly  1 . The danger is that communication signals may leak out from within the enclosure through the small openings formed by each screw  2 . Given the sophistication of today&#39;s eavesdropping techniques, even small leaks can provide an adversary with enough information to place people&#39;s lives at risk. 
         [0007]    Accordingly, what is needed are improved methods and devices for reducing communication and power signal leakages from filter assemblies, shielded enclosures and the like. 
       SUMMARY OF THE INVENTION 
       [0008]    The present inventors discovered that the risk of leakage could be reduced by, among other things, reducing the number of fasteners needed to connect filters to an assembly. In one embodiment of the invention, one or more filters or other components may be connectibly inserted, attached to, or otherwise made a part of, an optimized frame of an assembly by first forming one or more optimized cavities or receptacles in the frame and then inserting, etc., one or more of the filters into a formed cavity or receptacle. The use of optimized cavities or receptacles greatly reduces the number of exterior fasteners needed to connect components to an assembly which, in turn, reduces leakage. 
         [0009]    Additional embodiments of the invention, which provide additional improvements over existing assemblies, are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  depicts an example of an existing assembly. 
           [0011]      FIGS. 2 and 3  depict examples of optimized frames used as a part of assemblies which include one or more optimized cavities or receptacles according to embodiments of the invention. 
           [0012]      FIGS. 4-7  depict cross sectional views of assemblies according to embodiments of the invention. 
           [0013]      FIGS. 8A and 8B  depict embodiments of the invention using one or more alternative bulkheads. 
           [0014]      FIGS. 9A ,  9 B and  10  depict alternative geometrical designs for assemblies according to embodiments of the invention. 
           [0015]      FIG. 11  depicts an assembly that includes heat sinks according to another embodiment of the invention. 
           [0016]      FIG. 12  depicts an exemplary manufacturing process according to one or more embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to  FIG. 2 , there is shown one example of a frame  10  which may part of an assembly according to one embodiment of the invention. As shown, the frame  10  includes one or more cavities or receptacles (collectively referred to as “cavities” or “cavity”)  20   a - 20   d  and  30   a - 30   e.  At any given time some cavities, such as cavities  20   a - 20   d,  may receive one or more components (e.g., power filters, electrical connectors and components, optical connectors and components, radio-frequency identification (RFID) microchips and a registered-jack (RJ) type telecommunication jacks) which are intended to be, or are, connectibly inserted into, attached to, or otherwise placed into, a cavity. The inclusion of an RFID chip in a machined cavity on, for example, the outside of the assembly may allow for the identification, tracking, etc., of one or more of the other components within an assembly. Further, other cavities, such as cavities  30   a - 30   e,  may be used as spare cavities (i.e., available to receive one or more components in the future). 
         [0018]    It should be understood that any number of filters and other electronic, mechanical, optical, electrical components (to name just a few examples) may be connectibly inserted, attached to, or otherwise placed into a cavity  20   a  through  30   e.  Further, it should be understood that the number of cavities shown in  FIG. 2  is for illustrative purposes only; it being understood that their number may vary and still fall within the scope of the present invention. 
         [0019]    As used herein the word “filter” may mean a single filter, such as an RF power or signal (analog or digital) filter, or one made of several components assembled in one or more cavities separated by bulkhead(s) (see  FIGS. 8A and 8B ), or a circuit board that includes filtering components, or a final assembly. In accordance with embodiments of the invention, a filter may be connected to either copper or optical fiber transmission lines. Yet further, a filter may include optical fiber, optical components, optical-to-electrical components, and/or electrical-to-optical components. 
         [0020]    In accordance with embodiments of the invention, the shapes and sizes of the cavities  20   a - 20   d  and  30   a - 30   e  may be varied in order to properly receive a particular component. 
         [0021]    Also shown is cavity  40  that is used to receive one or more communications type conduit, wiring, or cabling such as optical cables. 
         [0022]      FIG. 3  depicts an alternative frame  100  that includes filled cavities  200   a - f  and spare cavities  300   a - l  according to another embodiment of the invention. As illustrated in  FIGS. 2 and 3 , the cavities may be arranged in a compact manner in order to make efficient use of the available space on the frames  10 , 100  so that machining of each cavity may be optimized around any component received by the cavities  200   a  through  300   l.    
         [0023]    As is known in the art, because of the difficulty in bending or otherwise shaping thin metal in 3-dimensions with the precision required, most filters are formed using shapes that are the easiest to create, such as cylindrical or a “shoe box” designs (so-called “tin can” designs). 
         [0024]    Realizing this, the present inventors provide for an optimized frame to receive filters and other components that may take the form of complex shapes that can be very accurately reproduced. CAD-based designs and CNC machining allow for the design and creation of such complex, yet precisely cut, shapes. 
         [0025]    As mentioned above, the use of CAD designs and CNC machining also helps achieve the efficient and optimum use of available space on a frame, such as frame  100 , so that the formation (e.g., machining) of each cavity may be optimized around any component received by cavities  20   a - 20   d,    30   a - 30   e  and  200   a  through  300   l . Given the type of components desired to be placed into a frame, and the desired frame size, the present invention provides optimum formed cavities, frames and components.  FIGS. 2 and 3  are simplified illustrations of how cavities may be sized, shaped, positioned in a frame and placed with respect to other cavities in order to optimize space for a given design. 
         [0026]    In accordance with embodiments of the invention, and as shown in  FIGS. 1-10 , cavities may be formed using parallel walls and still form very complex shapes. 
         [0027]    Referring now to  FIG. 4 , there is shown a cross-sectional view of an assembly  60  taken along axis A-A of  FIG. 2 . As shown in this view, the assembly  60  includes a filled cavity  20   a  and a spare cavity  30   c.  In one embodiment of the invention the filled cavity  20   a  may receive a power filter  70 . Further, communication signals may be input into the filter  70  at one end  41  and output at another end  42 . As shown the assembly  60  is oriented such that end  41  receives signals from sources outside a shielded enclosure  80  or the like (only a portion of the outer layer of enclosure  80  is shown) while end  42  outputs signals into the enclosure. Yet further, filter  70  may pass signals in both directions (i.e., into, and out of, the enclosure). The type of enclosure  80  may vary widely from a lightweight fabric to a more rigid, or sheet-metal based Tempest-like enclosure to give just a few examples. 
         [0028]    Though referred to in the singular, it should be understood that the filter  70  may comprise one or more components (as shown in  FIG. 4 ). In a further embodiment of the invention, when optical fiber is used to carry communication signals and the like into the enclosure  80  one or more additional components may be added to the cavity  20   a  or  30   c  or made a part of the filter  70  to allow for the transmission, filtering and/or conversion, if needed, of optical signals to electrical signals (O/E) and, if needed, conversion back from electrical signals to optical signals (E/O). In the case where no O/E or E/O conversions are necessary, the filter  70  and any additional component may be all optical components. Yet further, analog/digital optical converters, as well as passive and active optical components may be added to the cavity  20   a  or  30   c  or made a part of the filter  70  as required. 
         [0029]    Also shown are variable flanges  51   a  and  b  for attaching the assembly to the enclosure  80 . As shown in this embodiment, the assembly  60  protrudes outward from the enclosure  80 . 
         [0030]    The assembly  60  in  FIG. 4  also depicts other features (e.g., potting wax or foam) which are evident from the figure itself and, thus, need not be discussed in detail or repeated here. In addition, rather than depict all of the various connections required to make the filter  70  shown in  FIG. 4  operable such connections have been omitted for the sake of clarity, such connections being known to those skilled in the art. Similarly, in the assemblies shown in  FIGS. 5-7  the internal and external connections, all known to those skilled in the art, have been omitted for the sake of clarity. 
         [0031]      FIG. 5  depicts an alternative embodiment of an assembly  61  that is connected to an enclosure  81  in such a way that the assembly protrudes into the enclosure  81 . 
         [0032]      FIG. 6  depicts an alternative embodiment of an assembly  62  that is connected to an enclosure  82  by flanges  53   a  and  b  in such a way that the assembly  62  can be centered with respect to a perimeter of the enclosure  82  in order to minimize the dimensions of the assembly  62 . As illustrated in  FIGS. 4-7  the position of the flanges may be varied in order to provide different structural features and/or functions. 
         [0033]      FIG. 7  depicts an alternative embodiment of an assembly  63 , where the thickness of the frame  1000  may be varied in order provide a more compact, optimum and tight fit for components  700  received within cavity  20   a . Said another way, the frame&#39;s  1000  thickness may be varied in accordance with the dimensions and other characteristics of the components  700  that are received by the cavity  20   a.    
         [0034]      FIGS. 8A and 8B  depict vertical and horizontal bulkheads  90 - 99 . In one embodiment of the invention horizontal bulkheads may help provide physical, electrical and RF isolation of the filters and/or components placed within cavities. Such bulkheads may be connected to an assembly by any number of means, including soldering. In yet another embodiment of the invention, vertical bulkheads may also be included in an assembly to provide isolation as well. For ease of machining and assembly, it may be desirable to install components on a bulkhead prior to installing the bulkhead in an assembly. 
         [0035]      FIGS. 9A and 9B  depict two additional, alternative assemblies  64   a  and  b . As shown, the cavities  2000   a,b  and components  7000   a,b  included within assembly  64   a  form a single layer. In comparison, the cavities  2001   a,b  and  2002   a,b  and components  7001   a,b  and  7002   a,b  included within assembly  64   b  form two (or more layers). 
         [0036]      FIG. 10  depicts a number of geometric shapes (e.g., square, circular, rectangular, rounded) that an assembly may take the form of, it being understood that the shapes shown are just some of the many shapes that an assembly may take the form of. 
         [0037]      FIG. 11  depicts the formation of one or more heat sinks  66  on a lid  67  of an assembly  65  according to one embodiment of the invention. Such heat sinks help dissipate heat from the assembly and its components. 
         [0038]      FIG. 12  depicts an exemplary manufacturing process which may be followed to make assemblies in accordance with aspects of the present invention. 
         [0039]    Backtracking somewhat, it should be understood that machined, metal or metal alloy (e.g., aluminum) billets may be used as frames/assemblies in order to provide strength. Further, machined parts may receive a special surface treatment to allow increased conductivity, allow for soldering and reduce the risk of corrosion. Alternatively, as generally illustrated by some of the designs shown in  FIG. 10  the frame may be made from a metal casting to realize efficient use of raw material and lower costs if large, production quantities are required. 
         [0040]    The description above provides some examples of the scope of the present invention. It is not intended to be an exhaustive description of the many examples of the invention. Such a description would be impractical to write.