Abstract:
A coaxial cable connector and method that will direct the electromagnetic field carrying the electrical signal in a coaxial cable to the inner surface of a conductive layer of the foil of the cable, as opposed to the outer surface. With the electrical signals traveling on the inner surface of the foil conductive layer, the foil conductive layer serves as a contiguous gap-free shield to prevent the ingress and/or egress of RFI.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/754,874, filed Apr. 6, 2010, which claims the benefit of U.S. Provisional Application No. 61/166,956, filed on Apr. 6, 2009, both of which are incorporated by reference herein in their entireties. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to connectors for terminating coaxial cable. More particularly, the present disclosure relates to a coaxial cable connector having improved radio frequency integrity (RFI) sealing. 
         [0003]    It has long been known to use coaxial cable to carry communication signals from an external source to various electronic devices such as televisions, radios and the like. Conventional coaxial cables typically include a center conductor surrounded by an insulator. A conductive foil is disposed over the insulator and a braided conductive shield surrounds the foil covered insulator. An outer insulative jacket surrounds the shield. 
         [0004]    It is also well known to use connectors to terminate coaxial cable so as to connect the cable to the various electronic devices. Prior art coaxial connectors generally include a connector body having an annular collar for accommodating the coaxial cable, an annular nut rotatably coupled to the collar for providing mechanical attachment of the connector to an external device and an annular post interposed between the collar and the nut. A resilient sealing O-ring may also be positioned between the collar and the nut at the rotatable juncture thereof to provide a water resistant seal thereat. The collar includes a cable receiving end for insertably receiving an inserted coaxial cable and, at the opposite end of the connector body, the nut includes an internally threaded end extent permitting screw threaded attachment of the body to an external device. 
         [0005]    This type of coaxial connector further typically includes a locking sleeve to secure the cable within the body of the coaxial connector. The locking sleeve, which is typically formed of a resilient plastic, is securable to the connector body to secure the coaxial connector thereto. In this regard, the connector body typically includes some form of structure to cooperatively engage the locking sleeve. Such structure may include one or more recesses or detents formed on an inner annular surface of the connector body, which engages cooperating structure formed on an outer surface of the sleeve. A coaxial cable connector of this type is shown and described in commonly owned U.S. Pat. No. 6,530,807. 
         [0006]    In order to prepare the coaxial cable for termination, the outer jacket is stripped back exposing an extent of the braided conductive shield which is folded back over the jacket. A portion of the insulator covered by the conductive foil extends outwardly from the jacket and an extent of the center conductor extends outwardly from within the insulator. 
         [0007]    Upon assembly, a coaxial cable is inserted into the cable receiving end of the connector body, wherein the annular post is forced between the foil covered insulator and the conductive shield of the cable. In this regard, the post is typically provided with a radially enlarged barb to facilitate expansion of the cable jacket. The locking sleeve is then moved axially into the connector body to clamp the cable jacket against the post barb providing both cable retention and a water-tight seal around the cable jacket. The connector can then be attached to an external device by tightening the internally threaded nut to an externally threaded terminal or port of the external device. 
         [0008]    The design objective of coaxial cables is to carry the electromagnetic field between the inner and outer conductor, while providing protection from external signal ingress, which may cause interference with the signal being transmitted. However, as community television (CATV) systems have become more sophisticated in carrying many more channels of analog and digital information, the problems of interference caused by the ingress of radio frequency (RF) signals have grown. 
         [0009]    The conductive foil surrounding the center dielectric of newer coaxial cable designs include a layer of aluminum laminated on a layer of a polyester (PET) film (Mylar) tape. The foil is wrapped around the center dielectric with the Mylar layer making contact with the dielectric and with the aluminum layer forming the outer surface of the foil. Conventionally, the electrical signals will travel through the cable on the outer surface of the aluminum layer of the foil due to a phenomenon known in the field as the skin effect. 
         [0010]    To shield the electrical signals traveling along the outer surface of the foil from RF interference, conventional coaxial cables typically include a conductive shield surrounding the foil. However, because the conductive shield surrounding the foil typically has a braided construction to provide flexibility to the cable, the electrical signals travelling on the outer surface of the foil are vulnerable to interference from RF energies due to the gaps in the shield resulting from the braided construction. 
         [0011]    Some coaxial cable designs address this issue by providing an additional conductive foil layer to improve shielding. However, additional layers of foil also contribute to the cost of the cable. Moreover, while these newer conductive foil designs improve RF shielding to some extent, the present conventional coaxial cable connector interface designs do not provide reliable means to receive the energy from the foil layer. 
         [0012]    Accordingly, it would be desirable to provide a coaxial cable connector that will provide improved RFI shielding. It would be further desirable to provide a coaxial cable connector with an improved RF interface that will maintain the signal propagating function of the cable throughout the coupling interface for full shielding benefits. 
       SUMMARY OF THE INVENTION 
       [0013]    It is an object of the present disclosure to provide a coaxial cable connector for terminating a coaxial cable. 
         [0014]    It is a further object of the present disclosure to provide a coaxial cable connector having structure to enhance RF coupling and sealing. 
         [0015]    In the efficient attainment of these and other objects, the present invention provides a coaxial cable connector that will direct the electromagnetic field carrying the electrical signal to the inner surface of the conductive layer of the foil, as opposed to the outer surface. With the electrical signals traveling on the inner surface of the foil conductive layer, the foil conductive layer serves as a contiguous gap-free shield to prevent the ingress and/or egress of RFI. 
         [0016]    To force the electrical signals to the inner surface of the foil conductive layer, in one embodiment, the connector of the present invention generally includes a connector body having a forward end and a rearward cable receiving end for receiving a cable, a post disposed in the forward end of the connector body and an annular signal ring disposed within a forward end of the post. The annular sealing ring engages the conductive layer of the foil, thereby delivering electrical signals to the inner surface of the foil conductive layer. 
         [0017]    In a preferred embodiment, the signal ring includes a tubular body portion and a radially enlarged head portion, wherein the body portion preferably terminates at a sharp edge. The signal ring further preferably includes a tubular tensioning sleeve extending axially from the head portion in a forward direction opposite the tubular body portion. The tubular tensioning sleeve preferably includes at least one axial slot formed therein and a rounded forward end forming a bulbous rim. 
         [0018]    In an alternative embodiment, the coaxial cable connector of the present invention includes a post having an inner surface designed to make electrical and mechanical contact with the conductive foil surrounding the insulative core of the cable. In this manner, electrical signals are prevented from traveling on the outer surface of the foil, but instead are forced to travel on the inner surface of the foil conductive layer. 
         [0019]    In this alternative embodiment, the coaxial cable connector generally includes a connector body having a forward end and a rearward cable receiving end for receiving a cable and an annular post disposed within the connector body, wherein the post has an inner radial surface forming a central bore for receiving a foil covered dielectric portion of the coaxial cable. The central bore is defined by a first portion having a first inner diameter and a second portion having a second inner diameter, wherein the second inner diameter is smaller than the first inner diameter, whereby the inner radial surface forming the second portion of the central bore makes contact with the foil covered dielectric portion of the coaxial cable. 
         [0020]    The first portion of the central bore is preferably disposed at a rearward end of the post adjacent the rearward cable receiving end of the connector body and the second portion of the central bore is disposed at a forward end of the post opposite the rearward cable receiving end of the connector body. 
         [0021]    The inner surface of the post can be designed as a tapered surface, a broached surface or a knurled surface. The inner surface of the post can also include one or more protrusions, tree pans or steps to provide one or more areas of the inner surface having a reduced diameter for making contact with the cable foil. 
         [0022]    Specifically, the inner radial surface forming the second portion of the central bore can be formed with a plurality of axial grooves defining a broach structure or a plurality of grooves defining a knurl structure. The inner radial surface forming the central bore can be tapered in an axial direction, wherein the diameter of the central bore gradually decreases in a rearward direction away from the rearward cable receiving end of the connector body. 
         [0023]    The second portion of the central bore can be defined by a tree pan structure, wherein the tree pan structure has an inner radial surface stepped radially inward with respect to the first portion of the central bore and a ramped surface transitioning the inner radial surface with the first portion of the central bore. The ramped surface tapers radially outwardly in a rearward direction away from the rearward cable receiving end of the connector body, whereby the inner radial surface and the ramped surface meet at a sharp edge facing the rearward cable receiving end of the connector body. 
         [0024]    The present disclosure further involves a method for shielding electrical signals traveling in a coaxial cable connector from interference. The method generally includes the step of using a coaxial cable connector to direct the electromagnetic field carrying the electrical signal to the inner surface of a conductive layer of a foil surrounding an insulative core of the cable, wherein the coaxial cable connector prevents the electrical signals from migrating to an outer surface of the conductive foil, and wherein the foil conductive layer serves as a contiguous gap-free shield to prevent the ingress of RFI. 
         [0025]    In one embodiment, the method includes the steps of inserting an end of the cable into a rearward cable receiving end of a connector body of the connector, engaging the end of the cable with a rearward end of an annular post coupled to the connector body of the connector during the cable inserting step and axially moving an annular signal ring disposed in a forward end of a central bore of the annular post in a rearward direction, whereby a rearward end of the annular signal ring engages the conductive foil at the end of the cable. In this manner, the outer surface of the conductive foil of the cable is forced against an inner conductive surface of the post by the rearward end of the annular signal ring during the step of axially moving the annular signal ring. 
         [0026]    In an alternative embodiment, the method includes the steps of forcing the outer surface of the conductive foil against an inner conductive surface of an annular post disposed in the connector, by using internal structure of the post. Specifically, the post has an inner radial surface forming a central bore for receiving a conductive foil covered dielectric portion of the coaxial cable, wherein the central bore is defined by a first portion having a first inner diameter and a second portion having a second inner diameter. The second inner diameter is smaller than the first inner diameter whereby the inner radial surface forming the second portion of the central bore makes contact with the foil covered dielectric portion of the coaxial cable. 
         [0027]    A preferred form of the coaxial connector, as well as other embodiments, objects, features and advantages of this invention, will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in conjunction with the accompanying drawings 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a front perspective view of a prepared end of a coaxial cable. 
           [0029]      FIG. 1   a  is an enlarged cross-sectional view of a portion of the cable shown in  FIG. 1  showing the electrical signal flow according to the prior art. 
           [0030]      FIG. 1   b  is an enlarged cross-sectional view of a portion of the cable shown in  FIG. 1  showing the electrical signal flow as a result of the present invention. 
           [0031]      FIG. 2  is a front perspective cross-sectional view of a first embodiment of the coaxial cable connector of the present invention. 
           [0032]      FIG. 3  is a cross-sectional view of the connector shown in  FIG. 1  in an uncompressed condition. 
           [0033]      FIG. 4  is a cross-sectional view of the connector shown in  FIG. 1  in a compressed condition. 
           [0034]      FIG. 5  is a cross-sectional view of the coaxial cable connector of the present invention in an uncompressed condition and showing an alternative embodiment of the annular signal ring. 
           [0035]      FIG. 6  is an enlarged cross-sectional view of the coaxial cable connector of the resent invention being attached to a terminal port. 
           [0036]      FIG. 7  is a cross-sectional view of the coaxial cable connector of the present invention in an uncompressed condition and showing another alternative embodiment of the annular signal ring. 
           [0037]      FIG. 8   a  is an end view of an alternative embodiment of the post according to the present invention. 
           [0038]      FIG. 8   b  is a cross-sectional view of the post shown in  FIG. 8   a  taken along the line  8   b - 8   b.    
           [0039]      FIG. 9  is a cross-sectional view of another alternative embodiment of the post according to the present invention. 
           [0040]      FIG. 10  is a cross-sectional view of still another alternative embodiment of the post according to the present invention. 
           [0041]      FIG. 11  is a cross-sectional view of yet another alternative embodiment of the post according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    Referring first to  FIG. 1 , a conventional coaxial cable  100  includes an inner conductor  102  formed of copper or similar conductive material. Surrounding the inner conductor  102  is an insulator  104  formed of a dielectric material, such as a suitably insulative plastic. A metallic foil  106  is disposed over the insulator  104  and a metallic braided shield  108  is positioned in surrounding relationship around the foil covered insulator. Covering the braided shield  108  is an outer insulative jacket  110 . 
         [0043]    As discussed above, the conductive foil  106  is typically a laminated structure including a Mylar, or other insulative layer  106   a  and a conductive layer  106   b.  The foil  106  is wrapped around the dielectric core  104  so that the Mylar layer  106   a  forms the inner surface of the foil in contact with the core  104  and the conductive layer  106   b  forms the outer surface of the foil. As discussed above, the design of conventional coaxial cable connectors results in a signal flow  112  on the outer surface  106   b ′ of the conductive layer  106   b  of the foil  106 , as shown in the prior art rendering of  FIG. 1   a.    
         [0044]    As will be discussed in further detail below, the coaxial cable connector of the present invention results in a signal flow  112  on the inner surface  106   b ″ of the conductive layer  106   b  of the foil, between the Mylar layer  106   a  and the conductive layer  106   b,  as shown diagrammatically in  FIG. 1   b . With the signal flow  112  provided on the inner surface  106   b ″ of the conductive layer  106   b  of the foil  106 , the conductive layer  106   b  will serve as a continuous RF shield for the signals, in addition to the braided shield  108 . The result is a dramatic improvement in RF shielding. 
         [0045]    Turning now to  FIGS. 2-4 , a first embodiment of the coaxial cable connector  10  of the present invention is shown. The connector  10  generally includes a connector body  12 , a nut  14  rotatably connected to the connector body, an annular post  16  disposed within the connector body and an annular signal ring  18  disposed within the annular post. As will be discussed in further detail below, the connector  10  of the present invention further preferably includes a locking sleeve  20  movably coupled to the connector body  12 . 
         [0046]    The connector body  12 , also called a collar, is an elongate generally cylindrical member, which can be made from plastic or from metal or the like. The body  12  has a forward end  22  coupled to the post  16  and the nut  14  and an opposite cable receiving end  24  for insertably receiving the locking sleeve  20 , as well as a prepared end of a coaxial cable  100  in the forward direction as shown by arrow A in  FIG. 2 . The cable receiving end  24  of the connector body  12  defines an inner sleeve engagement surface for coupling with the locking sleeve  20 . The inner engagement surface is preferably formed with detent structure, which cooperates with mating detent structure provided on the outer surface of the locking sleeve  20 . 
         [0047]    The locking sleeve  20  is a generally tubular member having a rearward cable receiving end  28  and an opposite forward connector insertion end  30 , which is movably coupled to the inner surface of the connector body  12 . As mentioned above, the outer cylindrical surface of the sleeve  20  includes a plurality of ridges or projections, which cooperate with the structure formed in the inner sleeve engagement surface of the connector body  12  to allow for the movable connection of the sleeve  20  to the connector body  12  such that the sleeve is lockingly axially moveable along arrow A toward the forward end  22  of the connector body from a first position, as shown in  FIG. 3 , which loosely retains the cable  100  within the connector  10 , to a more forward second position, as shown in  FIGS. 2 and 4 , which secures the cable within the connector. 
         [0048]    The locking sleeve  20  further preferably includes a flanged head portion  32  disposed at the rearward cable receiving end  28  thereof. The head portion  32  has an outer diameter larger than the inner diameter of the body  12  and includes a forward facing perpendicular wall  34 , which serves as an abutment surface against which the rearward end of the body  12  stops to prevent further insertion of the sleeve  20  into the body  12 . A resilient, sealing O-ring (not shown) is preferably provided at the forward facing perpendicular wall  34  to provide a water-tight seal between the locking sleeve  20  and the connector body  12  upon insertion of the locking sleeve within the body. 
         [0049]    The connector  10  of the present invention further includes a nut  14  rotatably coupled to the forward end  22  of the connector body  12  so as to retain the connector body and the post  16  within the nut. The nut  14  includes an internally threaded surface  26  adapted for threaded connection with a mating externally threaded port terminal for providing mechanical attachment of the connector  10  to an external device. A resilient sealing O-ring (not shown) can be positioned in the nut  14  to provide a water resistant seal between the connector body  12 , the post  16  and the nut  14 . 
         [0050]    The connector  10  of the present invention further includes an annular post  16  coupled to the forward end  22  of the connector body  12 . The annular post  16  includes a flanged base portion  38  at its forward end for securing the post within the annular nut  14  and an annular tubular extension  40  extending rearwardly within the body  12  and terminating adjacent the rearward end  24  of the connector body  12 . The rearward end of the tubular extension  40  preferably includes a radially outwardly extending ramped flange portion or “barb”  42  to enhance compression of the outer jacket of the coaxial cable to secure the cable within the connector  10 . The tubular extension  40  of the post  16 , the locking sleeve  20  and the body  12  define an annular chamber  44  for accommodating the jacket and shield of the inserted coaxial cable. 
         [0051]    Disposed within the flanged base portion  38  at the forward end of the post  16  is the annular signal ring  18 . The ring  18  is made from a metallic material, such as brass, and includes an inner radial surface  43  defining a central bore  45  extending the length of the ring. The ring  18  further includes a tubular body portion  46  and a radially enlarged head portion  48  disposed at a forward end of the body portion. 
         [0052]    The body portion  46  has an outer diameter generally matching the inner diameter of the post  16  so as to permit a friction-fit or press-fit therebetween. In this case, the inner diameter of the central bore  45  of the ring  18  will be less than the inner diameter of the post  16  by an amount equal to the thickness of the ring body portion  46 . 
         [0053]    Alternatively, a radial recess or counter-bore  49  can be provided in the forward end of the post bore to receive the ring  18  in a press-fit relation. In this case, the radial depth of the recess  49  and the thickness of the ring body portion are chosen so that the inner diameter of the central bore  45  of the ring  18  is less than or equal to the inner diameter of the post  16 , for reasons that will be described below. 
         [0054]    The head portion  48  of the ring  18  has an outer diameter generally matching the outer diameter of the flanged base portion  38  of the post  16  so that both the ring and the post can be contained within the nut  14 . The head portion  48  also serves as an insertion stop between the ring  18  and the post  16  to prevent further rearward insertion of the ring in the post bore, as will be discussed in further detail below. 
         [0055]    The body portion  46  of the ring  18  preferably terminates at a sharp edge  50  at its rearward end opposite the head portion. The edge  50 , the function of which will be discussed in further detail below, preferably tapers inwardly from the outer surface of the body portion  46  toward the inner surface to form a radially outwardly expanding ramp on the rearward end of the ring  18 . 
         [0056]    The connector  10  of the present invention can be provided with the body portion  46  of the ring  18  fully inserted in the post  16  prior to assembly with a cable, as shown in  FIG. 4 . Alternatively, the connector  10  can be provided with the body portion  46  of the ring  18  partially withdrawn from the post  16 , as shown in  FIG. 3 . When provided in an initially, partially withdrawn position, the ring  18  can be subsequently driven rearward into the post  16  with a suitable compression tool (not shown) upon assembly of the connector  10  to a cable  100 . 
         [0057]    Upon assembly, a prepared end of a coaxial cable  100  is inserted through the rearward cable receiving end  28  of the sleeve ring  20  to engage the post  16  of the connector  10  in a conventional manner. As the cable  100  is initially inserted, the cable braid  108  and jacket  110  are separated from the foil  106  covering the insulator  104  by the sharp edge  42  of the annular post  16 . At the same time, the dielectric core  104  with the surrounding foil  106  is received within the central bore of the post  16 . 
         [0058]    Once the cable  100  is fully inserted in the connector body  12 , the locking sleeve  20  is moved axially forward in the direction of arrow A from the first position shown in  FIG. 3  to the second position shown in  FIG. 4 . This may be accomplished with a suitable compression tool. As the sleeve  20  is moved axially forward, the inner surface of the sleeve provides compressive force on the cable jacket  110  against the barb  42  of the annular post  16 . 
         [0059]    To permit the insertion of the foil covered core into the annular post  16 , the internal diameter of the post central bore is made slightly larger than the outer diameter of the foil covered core. However, this difference in diameters creates a clearance or a gap between the outer surface of the foil  106  and the inner surface of the annular post  16 . With conventional coaxial cable connectors, the electrical signals are drawn to this clearance causing a signal flow on the outer surface of the foil  106 , as described above. 
         [0060]    The annular signal ring  18  of the present invention prevents the electrical signals from migrating to the outer surface of the foil  106 , but instead directs the signals to the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106 , as shown in  FIG. 1   b . Specifically, the annular signal ring  18  of the present invention acts as an electrical dam, which blocks access to the outer surface of the foil and directs the signals instead to the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106 . This is accomplished in the following manner. 
         [0061]    If the connector  10  has been provided with the ring  18  already fully inserted in the post  16 , as shown in  FIGS. 2 and 4 , insertion of the cable  100  into the connector  10  will cause the foil  106  covering the dielectric  104  to come into contact with the rearward end of the ring  18 . More specifically, since the inner diameter of the central bore  45  of the ring body portion  46  is slightly less than the inner diameter of the post  16 , and therefore slightly less than the outer diameter of the cable foil  106  covering the cable insulator  104 , the sharp edge  50  of the body portion  46  of the ring  18  will make mechanical and electrical contact with the outer conductive layer  106   b  of the foil  106  as the cable  100  is inserted into the post  16 . 
         [0062]    Alternatively, in the embodiment where the connector  10  is provided with the ring  18  partially withdrawn from the post  16 , as shown in  FIGS. 3 ,  5  and  6 , the ring is subsequently driven into the post after the cable  100  has been inserted. The result, however, is the same in that the sharp edge  50  of the body portion  46  of the ring will be driven into the foil  106  so that the ring  18  will come into mechanical and electrical contact with the outer conductive layer of the foil  106 . 
         [0063]    In both embodiments, the ring  18  thus provides a continuous path for the signal between the terminal port (not shown, but would be attached to the connector  10  via the nut  14 ) and the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106 . The ring  18  further prevents the signal from entering the region between the outer surface  106   b ′ of the foil  106  and the inner surface of the post  16 . 
         [0064]    In other words, electrical signals traveling from a terminal port (not shown) will first come in contact with the radially enlarged head portion  48  and commence to travel to the inner radial surface  43  of the ring bore  45  due to the skin effect discussed above. The signals will continue to travel to the sharp edge  50  of the tubular body portion  46  where they come into contact with the conductive layer  106   b  of the foil  106 . Because the signals cannot penetrate through the conductive layer  106   b,  they will be forced to travel along the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106 . 
         [0065]    Thus, the ring  18  of the connector  10  according to the present invention provides a connection under the laminated foil  106  and over the center conductor dielectric  104  for superior signal flow. This improves performance of the braided over foil cable types, as used with  50  and 75-Ohm cables. The new method according to the present invention improves the cable to connector interface ground path by providing a shorter passageway, which reduces the effects of signal ingress and egress. The system also improves higher frequency performance. 
         [0066]    The signal ring of the present invention can also be provided with additional structural features to improve connection between the connector  10  and an externally threaded terminal port. Thus, as shown in  FIG. 5 , the connector  10   a  includes an annular signal ring  60  having a radially enlarged head portion  62  and a tubular body portion  64  extending axially from the head portion in the rearward direction, as described above. However, in this embodiment, the annular signal ring  60  further includes a tubular tensioning sleeve  66  extending axially from the head portion in the forward direction opposite the tubular body portion. 
         [0067]    Again, the body portion  64  has an outer diameter generally matching the inner diameter of the post  16  so as to permit a friction-fit or press-fit engagement therebetween and the head portion  62  of the ring  60  has an outer diameter generally matching the outer diameter of the flanged base portion  38  of the post  16  so that both the ring and the post can be contained within the nut  14 . Also, the ring  60  again defines a central bore  65  having an inner diameter less than the inner diameter of the post  16  so that the sharp edge  67  of the ring will engage the foil  106  of the cable  100 . 
         [0068]    The tubular tensioning sleeve  66 , however, is designed to maintain a short ground path connection between the connector  10   a  and a terminal port  65  ( FIG. 6 ) as the nut  14  of the connector  10   a  is tightened on the terminal port. With conventional coaxial cable connectors, if the connector is not properly installed to the fully tightened position for full metal to metal contact between the male and female inter port, a gap may be formed, wherein the passing signals within the ground patch will be subject to ingress and egress issues. By providing the tensioning sleeve  66 , the metallic signal ring  60  of the connector  10   a  of the present invention maintains a low value RF electrical inductance path between the male connector and female inter-port, even if the nut  14  of the connector is slightly loosened. As a result, the RF signal ground path integrity is preserved. 
         [0069]    Specifically, as shown in  FIG. 6 , the tubular tensioning sleeve  66  is adapted to bend or flex radially inward as the ring  60  is axially compressed against a terminal port  65  during attachment of the connector to the port. As the sleeve  66  bends inward, a resilient biasing force is created at the forward end of the ring  60 , which causes the sleeve to maintain contact with the terminal port  65  despite any slight axial movement therebetween. 
         [0070]    To enhance flexibility in the axial direction, the tubular tensioning sleeve  66  is preferably provided with a plurality of radially arranged axial slots  68  extending rearward from the forward most end of the ring  60  to permit the forward most end of the ring to freely bend inwardly. Specifically, the slots  68  facilitate slight radial movement of the end of the sleeve  66  upon axial compression of the ring  60  so that mechanical and electrical contact will be maintained between the ring  60  and the terminal port upon tightening and loosening of the nut  14  on the external thread  67  of the port  65 . Six slots  68  have been found to provide optimal electrical shielding performance in view of the cost to manufacture the ring  60 . 
         [0071]      FIG. 7  shows an alternative embodiment of an annular signal ring  70  having a slightly modified tubular tensioning sleeve  72 . In this embodiment, the forward most end of the tensioning sleeve  72  has been rounded to form a bulbous rim  74  at the end of the sleeve. This rim  74  acts as a cam surface to facilitate inward radial movement of the sleeve  72  upon axial compression of the ring  70 . (The bulbous rim  74  is shown in dashed lines in the enlarged view of  FIG. 6 .) 
         [0072]    Operation of the alternative ring embodiments  60 ,  70  is the same as that described above with respect to the ring  18 . In particular, as the cable  100  is fully inserted in the connector body  12 , and the locking sleeve  20  is moved axially forward in the direction of arrow A, the sharp edge of the body portion of the ring  18 ,  60 ,  70  will be driven into the conductive layer  106   b  of the foil  106  so that the ring will provide a continuous signal path to and from the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106  and block access to the outer surface  106   b ′ of the outer conductive layer  106   b  of the foil  106 . 
         [0073]    Direction of the signal to the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106  can also be achieved by providing structure integrally on the inner surface of the post to ensure that the outer conductive layer  106   b  of the foil  106  comes into direct contact with the post. 
         [0074]    Thus, a post  16   a  can be provided having a broach or knurl structure  80  formed on its inner radial surface  82 , as shown in  FIGS. 8   a  and  8   b . The broach or knurl structure  80  is preferably formed at the forward end of the post bore opposite the post barb  42  and is generally defined by an arrangement of grooves formed in the surface of the bore. In this manner, the post bore is defined by a rearward portion  84  having an inner diameter slightly larger than the foil covered dielectric core, as described above, to permit insertion of the foil covered dielectric core into the post  16   a,  and a forward broach structure portion  80  having a reduced diameter, as compared with the rearward portion  84 , for engaging the foil  106  as the cable is inserted into the connector. 
         [0075]    Alternatively, a post  16   b  can be provided having a protrusion or step  86  formed on its inner radial surface  82 , as shown in  FIG. 9 . Similar to the broach or knurl structure  80  described above, the step  86  is preferably formed at the forward end of the post bore opposite the post barb  42 . In this manner, the post bore is again defined by a rearward portion  84  having an inner diameter slightly larger than the foil covered dielectric core and a forward portion  86  having a reduced diameter, as compared with the rearward portion  84 , for engaging the foil  106  as the cable is inserted into the connector. 
         [0076]      FIG. 10  shows another alternative embodiment of a post  16   c,  which, in this case, has a tapered inner surface  88  defining the post bore. The tapered inner surface  88  has a diameter at its rearward end slightly larger than the foil covered dielectric core to permit insertion of the foil covered dielectric core into the post  16   a.  The diameter of the tapered inner surface  88  gradually decreases in the rearward direction away from the barb  42  so that the rearward portion of the post inner surface will engage the foil  106  as the cable is inserted into the connector. 
         [0077]    In yet another alternative embodiment, as shown in  FIG. 11 , a post  16   d  can be provided having a “tree pan” structure  90  formed on its inner radial surface  82 . The tree pan structure  90  is similar to the step  86  described above, but instead of smoothly transitioning with the inner radial surface  82 , as with the step  86  shown in  FIG. 9 , the reduced diameter portion of the bore defined by the tree pan structure  90  transitions with the inner radial surface  82  of the bore via a reverse cut or under cut  92 . Again, the tree pan structure  90  is preferably formed at the forward end of the post bore opposite the post barb  42  to define a rearward portion  84  having an inner diameter slightly larger than the foil covered dielectric core and a forward portion having a reduced diameter, as compared with the rearward portion  84 . However, due to the undercut transitioning the forward tree pan portion  90  with the rearward portion, the rearward end of the forward portion is formed with a sharp edge  94  for engaging the foil  106  as the cable  100  is inserted into the connector. 
         [0078]    In each of the embodiments shown in  FIGS. 8-11 , the post includes an internal central bore formed with an area of reduced inner diameter for engaging the foil  106  of the cable  100 . Once the outer conductive layer  106   b  of the foil  106  is in contact with the inner surface of the post  16 , the signal flow path to the outer surface  106   b ′ of the outer conductive layer  106   b  of the foil  106  is blocked. As a result, the electrical signals will instead migrate to the inner surface  106   b ″ of the outer conductive layer  106   b  of the foil  106 , wherein the outer conductive layer  106   b  will again serve as an RF shield for the signals. 
         [0079]    As a result of the present invention, the new interface provides numerous enhancements including: improved interface shielding (signal egress and ingress); reduced micro-reflections; reduced effects of passive intermodulation distortion; higher frequency bandwidth performance; and improved shielding performance allowing the use of lower percentage shielded cable types resulting in a cost savings related to replacing existing cables in obtaining better system performance. 
         [0080]    Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention. 
         [0081]    Various changes to the foregoing described and shown structures will now be evident to those skilled in the art. Accordingly, the particularly disclosed scope of the invention is set forth in the following claims.