Abstract:
An apparatus including a conductive sleeve including an outer-conductive surface and an inner passageway that extends from a first end at least partially to a second end. The passageway is adapted to receive and shield a device that provides at least one of a radio frequency path and an electrical current path. In one embodiment, movable flanges at an end of the sleeve are used for coupling the outer-conductive surface of the sleeve to a ground connection. In one embodiment, the sleeve may further be used to interconnect a pair of RF structures with ground connections at each end of the sleeve and with signal connections to the device at each end.

Description:
RELATED APPLICATIONS 
     This application claims the benefit under 35 USC 119(e) of prior provisional application 60/752,786, filed Dec. 12, 2005, which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     Radio frequency systems often include at least one radio frequency device that needs to be incorporated with other devices. Some radio frequency systems require that a radio frequency device is incorporated with one or more other radio frequency devices. The devices often need to be electrically isolated from each other for optimal system operation. In one exemplary system, the antennae in base stations of communication systems often receive more than one signal in more than one spectral range. In order to separate the different signals, the communication systems incorporate radio frequency filter systems such as a low pass filter and a resonant cavity of a band pass filter. A low pass filter is fixed and grounded inside a passageway of the resonant cavity of the band pass filter. In such filters, a stable contact between the low pass filter and the band pass filter is critical. 
     The technology to manufacture such radio frequency systems includes machining the body of a band pass filter out of a solid piece with a passageway in which the low pass filter is inserted. The passageway is positioned so that the filters share a common ground. Machining the body of a band pass filter out of a solid piece is an expensive process. It is less expensive to manufacture the body of the band pass filter by die casting the body. The die cast manufacturing process requires that the slot for the low pass filter be electroplated to adequately ground the low pass filer to the ground of the band pass filter. Electroplating in the closed area is difficult and often produces holes in the metallic layer so the ground is not adequate for the radio frequency system. 
     Assuring proper grounding of devices such as low pass filters is also problematic in other contexts. 
     SUMMARY 
     The embodiments of the present invention provide an inexpensive, reliable system for assuring proper grounding of a low pass filter and will be understood by reading and studying the following specification. 
     One aspect of the present invention provides an apparatus including a conductive sleeve that has an outer-conductive surface and an inner passageway that extends from a first end at least partially to a second end. The passageway is adapted to receive and shield a device that provides at least one of a radio frequency path and an electrical current path. 
     Another aspect of the present invention provides a method to electrically isolate a device. The method includes inserting the device into a conductive sleeve and grounding an outer-conductive surface of the conductive sleeve to a ground contact of a radio frequency device near at least one of a radio frequency path and an electrical current path for the device. 
     Another aspect of the present invention provides a method to electrically isolate a second radio frequency device. The method includes inserting a conductive sleeve into a first radio frequency device, the conductive sleeve operable to hold the second radio frequency device and grounding the conductive sleeve to a ground of the first radio frequency device. 
     Another aspect of the present invention includes a system to shield a device. The system includes means for grounding a conductive sleeve with a first radio frequency device and means for retaining the device within the conductive sleeve. 
     Another aspect of the present invention includes an apparatus including a non-conductive material with an inner passageway extending at least partially through a length of the non-conductive material and a conductive layer formed on an exterior surface of the non-conductive material, wherein the non-conductive material and the conductive layer form a sleeve adapted to receive a device. 
     Another aspect of the present invention includes an apparatus including a sleeve including an outer-conductive surface and an inner passageway that extends from a first end to a second end. The passageway is adapted to receive a first radio frequency device. The sleeve shields the first radio frequency device when the outer-conductive surface is operably attached to a ground in a second radio frequency device. 
    
    
     
       DRAWINGS 
       Embodiments of the present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the description of the preferred embodiments and the following figures in which: 
         FIGS. 1A-1C  illustrate block diagram views of a radio frequency system in accordance with one embodiment of the present invention. 
         FIG. 2  illustrates an oblique view of a conductive sleeve according to one embodiment of the present invention. 
         FIGS. 3A-3D  illustrate views of a conductive sleeve according to one embodiment of the present invention. 
         FIGS. 4A-4C  illustrate views of a second-end portion of the conductive sleeve according to an embodiment of the present invention. 
         FIGS. 5A-5D  illustrate views of a securing bracket operable to attach the conductive sleeve to a grounded radio frequency device according to an embodiment of the present invention. 
         FIG. 6  is a flow diagram of one embodiment of a method to electrically isolate a radio frequency device. 
         FIG. 7A  illustrates an exploded view of relative positions of a conductive sleeve, a device, a first radio frequency device and a second radio frequency device according to an embodiment of the present invention. 
         FIG. 7B  illustrates the operably positioned conductive sleeve, device, first radio frequency device and second radio frequency device of  FIG. 7A  according to an embodiment of the present invention. 
         FIG. 8A  illustrates an exploded view of relative positions of a conductive sleeve, a device, a first radio frequency device and a second radio frequency device according to an embodiment of the present invention. 
         FIG. 8B  illustrates the operably positioned conductive sleeve, device, first radio frequency device and second radio frequency device of  FIG. 8A  according to an embodiment of the present invention. 
         FIG. 9A  illustrates an exploded view of relative positions of a conductive sleeve, a device, and at least a first radio frequency device according to an embodiment of the present invention. 
         FIG. 9B  illustrates the operably positioned conductive sleeve, device and at least first radio frequency device of  FIG. 9A  according to an embodiment of the present invention. 
         FIG. 10  is a flow diagram of one embodiment of a method to electrically isolate two devices. 
         FIGS. 11A and 11B  illustrate views of a conductive sleeve operable according to an embodiment of the present invention. 
         FIG. 12  illustrates an oblique view of a securing bracket operable to attach a device to a first radio frequency device according to an embodiment of the present invention. 
     
    
    
     In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize features relevant to the present invention. Reference characters denote like elements throughout figures and text. 
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. 
       FIGS. 1A-1C  illustrate block diagram views of a radio frequency system in accordance with one embodiment of the present invention.  FIG. 1A  illustrates an exploded view of relative positions of the components of system  10  according to an embodiment of the present invention.  FIG. 1B  illustrates a top view of the first radio frequency device  40  in accordance with one embodiment of the present invention.  FIG. 1C  illustrates a side-cross-sectional view of a cavity  90  in the first radio frequency device  40  in which the conductive sleeve  24  and the device  20  are positioned. 
     The illustrated components of system  10  include a device  20 , the first radio frequency device  40  ( FIG. 1A ), an input/output connector  70 , an input/output connector  75  and a securing bracket  71  for attaching the conductive sleeve  24  in the cavity  90  of grounded first radio frequency device  40  according to an embodiment of the present invention. 
     As shown in  FIGS. 1A and 1B , the first radio frequency device  40  includes the cavity  90 . Cavity  90  is adapted to hold a device  20  inside a conductive sleeve  24 . The cavity  90  has a width W, a central length L ( FIG. 1B ), and an angle α ( FIG. 1B ) with respect to side  43 . Other widths, lengths and angles are possible. The opening to the cavity  90  is indicated by the arrow  91  ( FIG. 1A ). 
     At least a portion of the surface of the cavity  90  includes a first ground  193  and a second ground  194  of the grounded first radio frequency device  40 . The first ground  193  is also referred to here as “first ground contact  193 .” The second ground  194  is also referred to here as “second ground contact  194 .” The conductive sleeve  24  that houses the device  20  is inserted into the cavity  90  in contact with the second ground  194  and the first ground  193  of the first radio frequency device  40 . In one implementation of this embodiment, the second ground  194  and the first ground  193  are a common ground on the ground plane of the first radio frequency device  40 . In another implementation of this embodiment, the cavity  90  is a grounding plate. 
     As shown in  FIG. 1C , the device  20 , the conductive sleeve  24 , the securing bracket  71 , the input/output connector  70  and input/output connector  75  are operably positioned in the cavity  90 . The conductive sleeve  24  includes an outer-conductive surface  120  and an inner passageway  122  that extends from a second end  125  to a first end  127 . The inner surface  121  of the inner passageway  122  encircles the device  20 . 
     The input/output connector  70  goes through the hole  140  ( FIG. 1C ) that extends from the outer-conductive surface  120  of the conductive sleeve  24  to an inner surface  121  of the conductive sleeve  24  to make contact with the device  20 . Likewise the input/output connector  75  goes through the hole  141  ( FIG. 1C ) that extends from the outer-conductive surface  120  of the conductive sleeve  24  to an inner surface  121  of the conductive sleeve  24  to make contact with the device  20 . In this manner input/output connector  70  and input/output connector  75  are operable to electrically connect to the device  20  and to provide a portion of a radio frequency path  310  or an electrical current path  310 . The numerical indicator  310  in the accompanying drawings and as used in this document indicate either a radio frequency path or an electrical current path as will be understandable by one skilled in the art. If the device  20  is a radio frequency device, the path  310  is a radio frequency path. If the device  20  is an electronic or opto-electronic device, the path  310  is an electrical current path. In one implementation of this embodiment, the input/output connector  75  is not included in the system  10 . 
     The securing bracket  71  partially encircles a portion of the outer-conductive surface  120  near the hole  140 . The securing bracket  71  provides pressure to hold the conductive sleeve  24  securely in place within the first radio frequency device  40 . The securing bracket  71  attaches the conductive sleeve  24  to the radio frequency device  40  in contact with the first ground contact  193  and with the second ground contact  194 . 
     The conductive sleeve  24  contacts the first ground contact  193  in the first radio frequency device  40 , while the first ground contact  193  is in proximity to the at least one of the radio frequency path  310  and the electrical current path  310 . Likewise, the conductive sleeve  24  contacts the second ground  194  in the first radio frequency device  40  while the second ground contact  194  is in proximity to the radio frequency path  310  or the electrical current path  310 . Other configurations for conductive sleeves to contact a ground in respective radio frequency device are described below with reference to  FIGS. 7A ,  7 B,  8 A,  8 B,  9 A and  9 B 
     One implementation of this embodiment of the radio frequency system  10  does not include the securing bracket  71 . In another implementation of this embodiment of the radio frequency system  10 , the device  20  is a filter that needs to be shielded. In another implementation of this embodiment, the first radio frequency device  40  is a band pass filter. Such a band pass filter comprises, in one embodiment, a tunable cavity filter. The cavity filter portion of first radio frequency device  40  is constructed using existing or later-developed techniques. In another implementation of this embodiment, a device  20  and first radio frequency device  40  are electrically connected in parallel when positioned as illustrated in  FIG. 1C . In another implementation of this embodiment, the radio frequency device  40  is a band pass filter operably connected to a radio frequency antenna and the device  20  comprises a low pass filter electrically connected in parallel to the band pass filter  40 , wherein the low pass filter and the band pass filter are adapted to separate spectrally distinct radio frequency signals. 
     In another implementation of this embodiment, the device  20  is a radio frequency device. In another implementation of this embodiment, of this embodiment, the device  20  is a radio frequency low pass filter. In another implementation of this embodiment, the device  20  is one of an active electrical circuit, a passive electrical circuit, an active electro-optical circuit, a passive electro-optical circuit, an electrical element, an optical element, a radio frequency device, band pass filter, a band stop, a low pass filter, a notch filter, a printed circuit board, radio frequency traces, lasers, light emitting diodes, a straight pin and combinations thereof. In one implementation of this embodiment, the conductive sleeve is a conductive ductile material operable to cover the device in a shielding manner. 
       FIG. 2  illustrates an oblique view of a conductive sleeve  26  according to one embodiment of the present invention. The conductive sleeve  26  has an outer-conductive surface  120  and an inner passageway  122  that partially extends from a first end  127  to a second end  128 . The second end  128  is closed unlike the second end  125  of conductive sleeve  24 . The inner passageway  122  is enclosed by the inner surface  121 . The outer diameter D o  of the conductive sleeve  24  is less than the width W ( FIG. 1B ) of the cavity  90 . The length of the conductive sleeve  24  is less than the length L ( FIG. 1B ) of the cavity  90  so that the conductive sleeve  24  fits completely within the cavity  90  of the first radio frequency device  40 . 
     In this illustrated embodiment of sleeve  26 , the outer-conductive surface  120  is cylindrical. Other shapes are possible. In this illustrated embodiment of sleeve  26 , the inner passageway  122  is cylindrical. Other shapes are possible. In this illustrated embodiment of sleeve  26 , there is no hole on the side surface  120  of the sleeve  26  from the outer-conductive surface  120  to the inner surface  121 . In one implementation of this embodiment, there are one or more holes on the side surface  120  of the sleeve  26  from the outer-conductive surface  120  to the inner surface  121 . 
       FIGS. 3A-3D  illustrate views of the conductive sleeve  24  according to one embodiment of the present invention.  FIG. 3A  illustrates an oblique view of the conductive sleeve  24 .  FIG. 3B  illustrates a first side view of the conductive sleeve  24 .  FIG. 3C  illustrates a second side view of the conductive sleeve  24  in which the second side view is rotated 90 degrees from the first side view of  FIG. 3B .  FIG. 3D  illustrates a top view of the outward first end  127  of conductive sleeve  24 . The inner passageway  122  is designed to receive the device  20  ( FIGS. 1A and 1C ). 
     The conductive sleeve  24  has an outer-conductive surface  120  and an inner passageway  122  that extends from the second end  125  to the first end  127 . The second end  125  is open. The conductive sleeve  24  includes a first-end portion  130 , a second-end portion  132  and a main body portion  134 . The first-end portion  130  is near the first end  127 . The first-end portion  130  includes a hole  140  that extends from the outer-conductive surface  120  of the conductive sleeve  24  to an inner surface  121  of the conductive sleeve  24 . The input/output connector  70  extends through the hole  140  and is in electrical contact with the radio device  20  ( FIGS. 1A and 1C ). 
     The outer diameter of the conductive sleeve  24  is less than the width W ( FIG. 1B ) of the cavity  90 . The length of the conductive sleeve  24  is less than the length L ( FIG. 1B ) of the cavity  90  so that the conductive sleeve  24  fits completely within the cavity  90  of the first radio frequency device  40 . As shown in  FIGS. 3A-3C , the outer diameter D 1  ( FIGS. 3B-3C ) of the main body portion  134  is slightly smaller than the outer diameter D 2  ( FIGS. 3B-3C ) of the first-end portion  130  and the second-end portion  132 . In one implementation of this embodiment, the outer diameter D 1  of the main body portion  134  equals the outer diameter D 2  of the first-end portion  130  and/or the second-end portion  132 . The conductive sleeve  24  includes movable flanges  135  at the second-end portion  132  of the conductive sleeve  24 . 
     In this illustrated embodiment of sleeve  24 , the outer-conductive surface  120  is cylindrical. Other shapes are possible 
       FIGS. 4A-4C  illustrate views of the second-end portion  132  of the conductive sleeve  24  according to an embodiment of the present invention.  FIG. 4A  illustrates a side view of the second-end portion  132  including flanges  135 .  FIG. 4B  illustrates an enlarged view of the second end  125  of conductive sleeve  24 .  FIG. 4C  illustrates a cross-sectional side view of the second-end portion  132  and flanges  135 . 
     As shown in  FIG. 4B , eight movable flanges  135  encircle the inner passageway  122 . In other implementations of this embodiment, more than eight movable flanges or fewer than eight movable flanges are located at the second end  125  of the conductive sleeve  24 . The second end  125  of the conductive sleeve  24  is located on the outward end surfaces of the flanges  135 . The flanges  135  are attached to the first-end portion  130  at a crease-portion  126 . Gaps  136  between neighboring flanges  135  provide room for the flanges  135  to inwardly bend about the crease-portion  126  by a small angle. In one implementation of this embodiment, the flanges  135  bend by less than one degree about the crease portion  126 . In another implementation of this embodiment, the flanges  135  bend by less than five degrees about the crease portion  126 . The gaps  136  are designed to allow limited bending of the flanges  135 . When the conductive sleeve  24  ( FIGS. 3A-3D ) is inserted into the cavity  90  ( FIGS. 1A-1C ) the second end  125  of the flanges  135  bend slightly inward and the flat inward ends  125  are pushed parallel to the flat surface  46  ( FIGS. 1A and 1B ) of the first radio frequency device  40 . The surface  46  of the first radio frequency device  40  includes second ground  194  ( FIGS. 1B and 1C ) and the outer-conductive surface of the conductive sleeve  24  is grounded when the flat inward ends  125  are pushed against ground  194  in the flat surface  46 . In this manner, the flanges  125  stably contact the second ground contact  194  in the first radio frequency device  40 , wherein the second ground contact  194  is in contact with the outer-conductive surface  120  and in proximity to the at least one of the radio frequency path and the electrical current path  310 . As shown in  FIG. 4B , the movable flanges  135  are bent inward. 
       FIGS. 5A-5D  illustrate views of a securing bracket  71  operable to ground the device  20  with the first radio frequency device  40  according to an embodiment of the present invention.  FIG. 5A  illustrates a first oblique view of the securing bracket  71 .  FIG. 5B  illustrates a second oblique view of the securing bracket  71 .  FIG. 5C  illustrates a bottom view of the securing bracket  71 .  FIG. 5D  illustrates a side view of the securing bracket  71  in which the bottom face  77  is facing to the right. 
     In the illustrated embodiment, the securing bracket  71  includes an inset  78  having a shape that conforms to the shape of the outer-conductive surface  120  at the first-end portion  130  of the conductive sleeve  24 . The inset  78  is inset into the bottom face  77  of the securing bracket  71 . As shown in  FIGS. 5A-5D , the inset  78  is a radial inset having a radius of curvature R that conforms to the radius of curvature D 2 /2 ( FIGS. 3B and 3C ) of the outer-conductive surface  120  at a first-end portion  130  of the conductive sleeve  24 . Specifically, R is about equal to D 2 /2. 
     The inset  78  separates the body of the securing bracket  71  into a first-side region  80  positioned at a first side  81  of the radial inset  78  and a second-side region  82  positioned at a second side  83  of the radial inset  78 . 
     The securing bracket  71  includes holes  72  and  74 , which receive attachment fixtures, such as screws, attachment pins and the like. The attachment fixtures fixedly attach the securing bracket  71  to the first radio frequency device  40 . The hole  72  is located in the first-side region  80  of the securing bracket  71 . The hole  74  is located in the second-side region  82  of the securing bracket  71 . The securing bracket  71  is formed from materials such as metals and/or plastics. 
     When the conductive sleeve  24  is positioned in the of the first radio frequency device  40  as shown in  FIG. 1A , the first-end portion  130  of the conductive sleeve  24  is partially encircled by the inset  78  of the securing bracket  71 . The attachment fixtures are positioned through holes  72  and  74  so that the inset  78  of the securing bracket  71  contacts the first-end portion  130  of the outer-conductive surface  120  in order to hold the conductive sleeve  24  in the first radio frequency device  40 . 
       FIG. 6  is a flow diagram  600  of a method to electrically isolate a radio frequency device. The following discussion of flow diagram  600  is related to exemplary first radio frequency device  40 , securing bracket  71 , and conductive sleeve  24  as shown in  FIGS. 1A-1C  and  FIGS. 3-5 . In an exemplary embodiment, the device  20  is a second radio frequency device  20 . The following discussion of flow diagram  600  is applicable to other embodiments of the radio frequency assemblies, securing brackets and conductive sleeves. 
     At block  602 , the conductive sleeve  24  is inserted into a cavity  90  ( FIGS. 1A-1C ) of a first radio frequency (RF) device  40 . The conductive sleeve  24  is operable to hold a second radio frequency device  20 . 
     At block  604 , the conductive sleeve  24  is grounded to a ground, such as first ground  193  and/or second ground  194 , of the first radio frequency device  40 . Grounding occurs when the outer-conductive surface  120  touches the first ground  193  and/or second ground  194 . 
     At block  606 , the securing bracket  71  secures the conductive sleeve  24  to the first radio frequency device  40 . In one implementation of this embodiment, the securing bracket  71  secures the conductive sleeve  24  so that the outer-conductive surface  120  is touching first ground  193  and/or second ground  194  of the first radio frequency device  40 . 
     At block  608 , the second radio frequency (RF) device  20  ( FIG. 1C ) is inserted into the conductive sleeve  24  that is positioned within the first radio frequency device  40 . In one implementation of this flow diagram  600 , the second radio frequency device  20  is positioned within the conductive sleeve  24  and then the second radio frequency device  20  and conductive sleeve  24  are inserted, as a unit, within the first radio frequency device  40 . 
     At block  610 , the second radio frequency device  20  is aligned to at least one input/output connector  70 , so the input/output connector  70  is in electrical contact with the second radio frequency device  20 . 
     In this manner, the conductive sleeve  24  is grounded to form a stable first ground contact with the first radio frequency device  40  while the device  20  is electrically isolated from the first radio frequency device  40 . In another implementation of this flow diagram  600 , a device other than the second radio frequency device  20  of this exemplary embodiment is electrically isolated from the first radio frequency device  40 . 
       FIG. 7A  illustrates an exploded view of relative positions of a conductive sleeve  24 , a device  20 , a first radio frequency device  150  and a second radio frequency device  160  according to an embodiment of the present invention.  FIG. 7B  illustrates the operably positioned conductive sleeve  24 , device  20 , first radio frequency device  150  and second radio frequency device  160  of  FIG. 7A  according to an embodiment of the present invention. The device  20  is shown in outline as it is held within the sleeve  24 . The first radio frequency device  150  includes an input/output connector  170 . Other than the input/output connector  170 , the first radio frequency device  150  is grounded. The second radio frequency device  160  includes an input/output connector  180 . Other than the input/output connector  180 , the second radio frequency device  160  is grounded. The second radio frequency device  160  includes feature  185  that conforms in shape and size to the second-end portion  132 . 
     The securing bracket  71  clamps the first-end portion  130  ( FIG. 7A ) to the first radio frequency device  150  so that the input/output connector  170  extends through the hole  140  and contacts the device  20  while the outer-conductive surface  120  of the conductive sleeve  24  is grounded to the first radio frequency device  150 . The second-end portion  132  ( FIG. 7A ) of the sleeve  24  fits within the feature  185  ( FIG. 7A ) of the second radio frequency device  160  so that the input/output connector  180  contacts the device  20  and outer-conductive surface  120  of the conductive sleeve  24  is grounded to the second radio frequency device  160 . When the input/output connector  170  and the input/output connector  180  contact the device  20 , a radio frequency path  310  or an electrical current path  310  is established. 
     The conductive sleeve  24  is adapted to contact the ground in the first radio frequency device  150  in the grounded contact region generally indicated as  93  ( FIG. 7B ) in proximity to the radio frequency path  310  or the electrical current path  310 . Likewise, the conductive sleeve  24  is adapted to contact the ground in the second radio frequency device  160  in the grounded contact region generally indicated as  94  ( FIG. 7B ) in proximity to the radio frequency path  310  or the electrical current path  310 . 
     In this manner, the device  20  is retained in the conductive sleeve  24  while the outer-conductive surface  120  of the conductive sleeve  24  is grounded to the first radio frequency device  150  and the second radio frequency device  160  and the device  20  is electrically contacting the first radio frequency device  150  and the second radio frequency device  160 . 
       FIG. 8A  illustrates an exploded view of relative positions of a conductive sleeve  28 , a device  20 , a first radio frequency device  255  and a second radio frequency device  160  according to an embodiment of the present invention.  FIG. 8B  illustrates the operably positioned conductive sleeve  28 , device  20 , first radio frequency device  255  and second radio frequency device  160  of  FIG. 8A  according to an embodiment of the present invention. 
     The device  20  is shown in outline as it is held within the conductive sleeve  28 . The conductive sleeve  28  includes a first-end portion  330 , a second-end portion  132  and a main body portion  134 . The first-end portion  330  is similar to the second-end portion  132  as described above with reference to  FIGS. 4A-4C  and includes flanges  135 . The first-end portion  330  does not include a hole that extends from the outer-conductive surface  120  of the conductive sleeve  28  to an inner surface  121  of the conductive sleeve  28 . 
     The first radio frequency device  255  includes an input/output connector  270  and a feature  285  that conforms in shape and size to the first-end portion  330 . Other than the input/output connector  270 , the first radio frequency device  255  is grounded. The second radio frequency device  160  is as described above with reference to  FIGS. 7A-7B . 
     The first-end portion  330  ( FIG. 8A ) of the conductive sleeve  28  fits within the feature  285  ( FIG. 8A ) of the first radio frequency device  255 . When the input/output connector  270  contacts the device  20 , the outer-conductive surface  120  of the conductive sleeve  28  is grounded to the first radio frequency device  255 . 
     The second-end portion  132  ( FIG. 8A ) of the conductive sleeve  28  fits within the feature  185  ( FIG. 8A ) of the second radio frequency device  160 . When the input/output connector  180  contacts the device  20 , the outer-conductive surface  120  of the conductive sleeve  28  is grounded to the second radio frequency device  160 . When the input/output connector  270  and the input/output connector  180  simultaneously contact the device  20 , a radio frequency path  310  or an electrical current path  310  is established. 
     The conductive sleeve  28  is adapted to contact the ground in the first radio frequency device  255  in the grounded contact region generally indicated as  93  ( FIG. 8B ) in proximity to the radio frequency path  310  or the electrical current path  310 . The grounded contact region  93  is also referred to here as “first ground contact  93 .” Likewise, the conductive sleeve  28  is adapted to contact the ground in the second radio frequency device  160  in the grounded contact region generally indicated as  94  ( FIG. 8B ) in proximity to the radio frequency path  310  or the electrical current path  310 . The grounded contact region  94  is also referred to here as “second ground contact  94 .” 
     In this manner, the device  20  is retained in the conductive sleeve  28  while the outer-conductive surface  120  of the conductive sleeve  28  is grounded to the first radio frequency device  255  and the second radio frequency device  160  and the device  20  is electrically contacting the first radio frequency device  255  and the second radio frequency device  160 . In one implementation of this embodiment, the device  20  a third radio frequency device  20 . In this case, the inner passageway  122  in the conductive sleeve  24  is adapted to receive the third radio frequency device  20 . The conductive sleeve  24  shields the third radio frequency device  20  when the outer-conductive surface  120  is operably attached to the first ground contact  93  in the first radio frequency device  255  and is operably attached to the second ground contact  94  in the second radio frequency device  160 . 
       FIG. 9A  illustrates an exploded view of relative positions of a conductive sleeve  24 , device  20 , and at least a first radio frequency device  400  according to an embodiment of the present invention.  FIG. 9B  illustrates the operably positioned conductive sleeve  24 , device  20  and at least first radio frequency device  400  of  FIG. 9A  according to an embodiment of the present invention. 
     The device  20  is shown in outline as it is held within the conductive sleeve  24 . The conductive sleeve  24  includes a first-end portion  130 , a second-end portion  132  and a main body portion  134  as describe above with reference to  FIGS. 3A-3D . The radio frequency device  400  includes a first input/output connector  420  positioned perpendicular to a second input/output connector  410 . The second input/output connector  410  projects into a feature  185  that conforms in shape and size to the second-end portion  132 . Other than the first input/output connector  420  and the second input/output connector  410 , the radio frequency device  400  is grounded. 
     In one implementation of this embodiment, the radio frequency device  400  is two radio frequency devices. In this case, the first input/output connector  420  is correlated with a first radio frequency device in the radio frequency device  400  and the second input/output connector  410  is correlated with a second radio frequency device in the radio frequency device  400 . For the discussion related to  FIGS. 9A and 9B , the “at least a first radio frequency device  400 ” is referred to as “radio frequency device  400 .” 
     The second-end portion  132  ( FIG. 9A ) of the conductive sleeve  24  fits within the feature  185  ( FIG. 9A ) of the radio frequency device  400 . The input/output connector  410  contacts the device  20 . The outer-conductive surface  120  of the conductive sleeve  24  is grounded to the radio frequency device  400 . The securing bracket  71  clamps the first-end portion  130  ( FIG. 9A ) to the radio frequency device  400  at the input-output connector  420 . The input/output connector  420  extends through the hole  140  and contacts the device  20  while the outer-conductive surface  120  of the conductive sleeve  24  is grounded to the radio frequency device  400 . 
     When the input/output connector  420  and the input/output connector  410  simultaneously contact the device  20 , a radio frequency path  310  or an electrical current path  310  is established. The conductive sleeve  24  is adapted to contact the ground in the radio frequency device  400  in the grounded contact region generally indicated as  93  ( FIG. 9B ) in proximity to the radio frequency path  310  or the electrical current path  310  at the first-end portion  130 . Likewise, the conductive sleeve  24  is adapted to contact the ground in the radio frequency device  400  in the grounded contact region generally indicated as  94  ( FIG. 9B ) in proximity to the radio frequency path  310  or the electrical current path  310  at the second-end portion  132 . 
     In this manner, the device  20  is retained in the conductive sleeve  24  while the outer-conductive surface  120  of the conductive sleeve  24  is grounded to the radio frequency device  400 . In the embodiment in which the radio frequency device  400  is two radio frequency devices, the device  20  is a third radio frequency device  20  that is shielded from both the first radio frequency device and the second radio frequency device while all three radio frequency devices are operational. In this case, the inner passageway  122  in the conductive sleeve  24  is adapted to receive the third radio frequency device  20 . The conductive sleeve  24  shields the third radio frequency device  20  when the outer-conductive surface  120  is operably attached to the first ground contact  93  in the first radio frequency device and is operably attached to the second ground contact  94  in the second radio frequency device. 
       FIG. 10  is a flow diagram  1000  of one embodiment of a method to electrically isolate two devices. The following discussion of flow diagram  1000  is related to the implementations of the present invention as shown in  FIGS. 7A-9B . The flow diagram  1000  is applicable to other embodiments of the radio frequency assemblies, securing brackets and conductive sleeves. 
     At block  1002 , a device  20  is inserted into a conductive sleeve  24  or  28  ( FIG. 7A  or  8 A, respectively). At block  1004 , an exterior surface, such as outer-conductive surface  120  of the conductive sleeve  24 , is grounded to the first ground  93  of a first radio frequency device near a conductive path, such as radio frequency path  130  or electrical current path  130 , for the device  20 . The first radio frequency device can be first radio frequency device  150  as shown in  FIGS. 7A and 7B . Likewise, the first radio frequency device can be first radio frequency device  255  as shown in  FIGS. 8A and 8B . Additionally, the first radio frequency device can be radio frequency device  400  as shown in  FIGS. 9A and 9B . 
     If the first radio frequency device is a single radio frequency device  400  as shown in  FIGS. 9A and 9B , the flow proceeds to block  1006 . If the first radio frequency device is first radio frequency device  150  as shown in  FIGS. 7A and 7B , the flow proceeds to block  1008 . If the first radio frequency device is first radio frequency device  255  as shown in  FIGS. 8A and 8B , the flow proceeds to block  1008 . If the first radio frequency device is a first of two radio frequency devices that comprise the radio frequency device  400  as shown in  FIGS. 9A and 9B , the flow proceeds to block  1008 . 
     At block  1006 , the exterior surface  120  of the conductive sleeve  24  ( FIG. 9B ) is grounded to the second ground  94  of the radio frequency device  400  near the radio frequency path  310  or the electrical current path  310  for the device  20 . 
     At block  1008 , the exterior surface  120  of the conductive sleeve  24  or  28  ( FIG. 7B  or  8 B, respectively) is grounded to the second ground  94  of a second radio frequency device  160  near the radio frequency path  130  or the electrical current path  130  for the device  20 . 
       FIGS. 11A and 11B  illustrate views of a conductive sleeve  125  according to an embodiment of the present invention.  FIG. 11A  is an oblique view of the conductive sleeve  125 .  FIG. 11B  illustrates an end view of the conductive sleeve  125  from the first end  227 . 
     The conductive sleeve  125  includes a non-conductive material  200  with an inner passageway  222  extending through the length L SL  ( FIG. 11A ) of the non-conductive material  200  from that extends from a second end  225  to a first end  227 . A conductive layer  210  is formed on the exterior surface  250  of the non-conductive material  200 . In this illustrated embodiment, the outer-conductive surface  210  is rectangular. Other shapes for the outer-conductive surface are possible. The inner passageway  222  is designed to receive a first radio frequency device, such as a device  20  ( FIG. 3 ). As shown in  FIGS. 11A and 11B , the inner passageway  222  has an inner diameter D. In one implementation of this embodiment, the inner diameter varies along the length L SL  of the inner passageway  222 . 
     The conductive sleeve  125  includes a first-end portion  230 , a second-end portion  232  and a main body portion  234 . The first-end portion  230  is near the first end  227 . The first-end portion  230  includes a hole  240  that extends through the outer-conductive surface  210  and the non-conductive material  200  to an inner surface  221  of the conductive sleeve  125 . 
     The width W 1  of the conductive sleeve  125  is less than the width W ( FIG. 2B ) of the cavity  90 . Likewise, the height H 1  of the conductive sleeve  125  is less than the width W ( FIG. 2B ) of the cavity  90 . The length L SL  of the conductive sleeve  125  is less than the length L ( FIG. 2B ) of the cavity  90  so that the conductive sleeve  125  fits completely within the cavity  90  of the first radio frequency device  40 . 
     When the conductive sleeve  125  is inserted into the cavity  90  ( FIGS. 1A and 1B ), the second end  225  of the conductive sleeve  125  including the conductive layer  210  is pushed against the flat surface  46  ( FIG. 1B ) of the first radio frequency device  40 . The surface  46  of the first radio frequency device  40  is a grounded surface and the outer-conductive surface of the conductive sleeve  24  is grounded when the second end  225  of the conductive sleeve  125  including the conductive layer  210  is pushed against the flat surface  46 . In this manner, the conductive layer  210  forms a stable first ground contact with the first radio frequency device  40  when the sleeve  125  in inserted in the cavity  90 . 
     In one implementation of this embodiment as shown in  FIGS. 1A and 1B , the height and width dimensions of the main body portion  234  equals the height and width dimensions of the first-end portion  230  and the second-end portion  232 . In another implementation of this embodiment of the conductive sleeve  125 , the height and width dimensions of the main body portion  234  differ from the height and width dimensions of the first-end portion  230  and the second-end portion  232 . As shown in  FIG. 11A , conductive sleeve  125  does not include movable flanges at the second-end portion  232  of the conductive sleeve  125 . In one implementation of this embodiment, the conductive sleeve  125  includes movable flanges at the second-end portion  232  of the conductive sleeve  125 . In this case, the gap between the flanges is designed to accommodate the thickness of the flanges in order to allow the flanges to bend slightly to position the end faces parallel to the flat surface  46  ( FIG. 1B ) of the first radio frequency device  40 . 
     In one implementation of this embodiment, the inner passageway  222  is cylindrical and extends through a length of a metallic form. In one embodiment of this implementation, the diameter D of the inner passageway is about 3 mils greater than a largest diameter of the device  20 . In another implementation of this embodiment, the inner diameter varies along the length L SL  of the inner passageway  222 . 
     In the various implementations of embodiments of the conductive sleeves  24  and  125 , the sleeves are formed from one of a metal cylinder, a metallic form including a passageway extending at least partially through a length of the metallic form, a metallic form including a cylindrical passageway extending at least partially through a length of the metallic form, a plastic form coated on an exterior surface with a metal layer and including a passageway extending at least partially through a length of the plastic form, a plastic form coated on an exterior surface with a metal layer and including a cylindrical passageway extending at least partially through a length of the metal-coated plastic form, and a plastic cylinder coated on an exterior surface with a metal layer. Other shapes are possible. By way of example and not by way of limitation, the term “form” includes a variety of shapes including rectangular, rhombic, and cylindrical shapes that may be asymmetric about one or more axes of the form and that may have a non-uniform thickness along one or more lengths of the form. 
       FIG. 12  illustrates an oblique view of a securing bracket  271  operable to ground the device  20  with the first radio frequency device  40  according to an embodiment of the present invention. 
     The securing bracket  271  includes an inset  278  having a shape that conforms to the shape of the outer-conductive surface  210  at a first-end portion  230  of the conductive sleeve  125  ( FIGS. 11A and 11B ). As shown in  FIG. 12 , the inset  278  is a rectangular inset having a width of dimension W 1 +ΔW and a depth of dimension H 1 +ΔH. The dimension ΔW is small with respect to W 1  and the dimension ΔH is small with respect to H 1 . Thus, the inset  278  conforms to the outer-conductive surface  210  at a first-end portion  230  of the conductive sleeve  125 . 
     The inset  278  separates the body of the securing bracket  271  into a first-side region  280  positioned at a first side  281  of the inset  278  and a second-side region  282  positioned at a second side  283  of the inset  278 . The securing bracket  271  includes holes  272  and  274 , which receive attachment fixtures, such as screws, attachment pins and the like. The attachment fixtures attach the securing bracket  271  to the first radio frequency device  40 . The hole  272  is located in the first-side region  280  of the securing bracket  271 . In another implementation of this embodiment, the securing bracket  271  is strap. The securing bracket  271  is formed from a metals and/or plastics. Other materials are possible. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.