Abstract:
An assembly of mated coaxial connectors includes: a first connector with a first central conductor extension and a first outer conductor extension having a free end portion; and a second connector with a second central conductor extension and a second outer conductor extension having an outer body and an inner body with a gap therebetween. The first central conductor extension engages the second central conductor extension. The free end portion of the first outer conductor extension fits within the gap of the second outer conductor extension, such that the inner body applies radially outward pressure to the first outer conductor extension. At least one of the first outer conductor extension and the second outer conductor extension includes a flex member that deflects during axial engagement of the first and second connectors to apply axial pressure to the other of the first outer conductor extension and the second outer conductor extension.

Description:
RELATED APPLICATION 
       [0001]    The present invention claims priority from and the benefit of U.S. Provisional Patent Application No. 61/926,638, filed Jan. 13, 2014, and U.S. patent application Ser. No. 14/594,727, filed Jan. 12, 2015, the disclosures of which are hereby incorporated herein in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present application is directed generally to electrical cable connectors, and more particularly to coaxial connectors for electrical cable 
       BACKGROUND OF THE INVENTION 
       [0003]    Coaxial cables are commonly utilized in RF communications systems. A typical coaxial cable includes an inner conductor, an outer conductor, a dielectric layer that separates the inner and outer conductors, and a jacket that covers the outer conductor. Coaxial cable connectors may be applied to terminate coaxial cables, for example, in communication systems requiring a high level of precision and reliability. 
         [0004]    Coaxial connector interfaces provide a connect/disconnect functionality between a cable terminated with a connector bearing the desired connector interface and a corresponding connector with a mating connector interface mounted on an apparatus or on another cable. Typically, one connector will include a structure such as a pin or post connected to an inner conductor and an outer conductor connector body connected to the outer conductor; these are mated with a mating sleeve (for the pin or post of the inner conductor) and another outer conductor connector body of a second connector. Coaxial connector interfaces often utilize a threaded coupling nut or other retainer that draws the connector interface pair into secure electro-mechanical engagement when the coupling nut (which is captured by one of the connectors) is threaded onto the other connector. 
         [0005]    A new proposed 4.3/10 interface under consideration by the IEC (46F/243/NP) (hereinafter the 4.3/10 interface) is alleged to exhibit superior electrical performance and improved (easier) mating. The 4.3/10 interface includes the following features: (a) separate electrical and mechanical reference planes; and (b) radial (electrical) contact of the outer conductor, so that axial compression is not needed for high normal forces. An exemplary configuration is shown in  FIG. 1  and is described in detail below. The alleged benefits of this arrangement include: 
         [0006]    Increased mechanical stability, as the mechanical reference plane is now outside the RF path; 
         [0007]    Non-bottoming of the electrical reference plane (as contact is made in the radial direction)—therefore, normal (radial) forces are independent from coupling nut torque applied; 
         [0008]    Coupling nut torque reduction; 
         [0009]    Improvement in PIM performance as outer contact radial forces are independent of coupling nut torque applied; and 
         [0010]    Gang mating of several connectors as the electrical reference plane can float (axially). Therefore, tolerance stack-ups from connector to connector should have no effect. 
         [0011]    It may be desirable to provide connector designs that conform to the proposed 4.3/10 interface standard. 
       SUMMARY 
       [0012]    As a first aspect, embodiments of the invention are directed to an assembly of mated coaxial connectors. The assembly comprises; a first connector having a first central conductor extension and a first outer conductor extension, the first outer conductor extension having a free end portion; and a second connector having a second central conductor extension and a second outer conductor extension, the second outer conductor extension having an outer body and an inner body with a gap therebetween. The first central conductor extension engages the second central conductor extension to establish a first electrical connection. The free end portion of the first outer conductor extension fits within the gap of the second outer conductor extension, such that the inner body applies radially outward pressure to the first outer conductor extension to establish a second electrical connection. At least one of the first outer conductor extension and the second outer conductor extension includes a flex member that deflects during axial engagement of the first and second connectors to apply axial pressure to the other of the first outer conductor extension and the second outer conductor extension to augment the second electrical connection. 
         [0013]    As a second aspect, embodiments of the invention are directed to an assembly of mated coaxial connectors, comprising: a first connector having a first central conductor extension and a first outer conductor extension, the first outer conductor extension having a free end portion; a second connector having a second central conductor extension and a second outer conductor extension, the second outer conductor extension having an outer body and an inner body with a gap therebetween; and a coupling nut that engages the first outer conductor extension. The first central conductor extension engages the second central conductor extension to establish a first electrical connection. The free end portion of the first outer conductor extension fits within the gap of the second outer conductor extension, such that the inner body applies radially outward pressure to the first outer conductor extension to establish a second electrical connection. At least one of the first outer conductor extension and the second outer conductor extension includes a flex member that deflects during axial engagement of the first and second connectors to apply axial pressure to the other of the first outer conductor extension and the second outer conductor extension to augment the second electrical connection. The coupling nut engages the outer body of the second outer conductor extension but does not engage a free end of the outer body of the second outer conductor extension. 
         [0014]    As a third aspect, embodiments of the invention are directed to an assembly of mated coaxial connectors, comprising: a first connector having a first central conductor extension and a first outer conductor extension, the first outer conductor extension having a free end portion; and a second connector having a second central conductor extension and a second outer conductor extension, the second outer conductor extension having an outer body and an inner body with a gap therebetween. The first central conductor extension engages the second central conductor extension to establish a first electrical connection. The free end portion of the first outer conductor extension fits within the gap of the second outer conductor extension, such that the inner body applies radially outward pressure to the first outer conductor extension to establish a second electrical connection. Engagement of the first outer conductor extension and the inner body of the second outer conductor extension induces deflection in at least one of the first outer conductor extension and the inner body to create axial and radial pressure between the first outer conductor extension and the inner body. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0015]      FIG. 1  is a section view of a mated assembly of two coaxial connectors according to the prior art. 
           [0016]      FIG. 1A  is a greatly enlarged view of a portion of  FIG. 1  showing the interaction of the outer body of the outer conductor extension of one connector and the shoulder of the outer conductor extension of the second connector. 
           [0017]      FIG. 2  is a partial section view of a mated assembly of two coaxial connectors according to embodiments of the present invention. 
           [0018]      FIG. 2A  is an enlarged view of a portion of the assembly of  FIG. 2 . 
           [0019]      FIG. 3  is a partial section view of one coaxial connector according to embodiments of the present invention. 
           [0020]      FIG. 4  is a partial section view of a coaxial connector according to additional embodiments of the present invention. 
           [0021]      FIG. 5  is a perspective view of an insert for the coaxial connector of  FIG. 4 . 
           [0022]      FIG. 6  is a partial section view of a coaxial connector configured to mate with the coaxial connector of  FIG. 4 . 
           [0023]      FIG. 7  is a section view of the coaxial connector of  FIG. 4  mated with the coaxial connector of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The present invention is described with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments that are pictured and described herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It will also be appreciated that the embodiments disclosed herein can be combined in any way and/or combination to provide many additional embodiments. 
         [0025]    Unless otherwise defined, all technical and scientific terms that are used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the above description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this disclosure, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when an element (e.g., a device, circuit, etc) is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
         [0026]    Referring now to  FIG. 1 , a cross-section of a basic 4.3/10 interface configuration is shown therein and is designated broadly at  10 . The interface  10  includes a plug  30  that is to be connected with a mating jack  130  of the mating coaxial cable.  FIG. 1  shows the plug  30  and jack  130  in their mated condition. 
         [0027]    The plug  30  includes a central conductor extension  32 , an outer conductor extension  34 , and a dielectric spacer  36 . The central conductor extension  32  has a generally cylindrical post  32   a  with a conical free end and is configured to be attached at its opposite end to the center conductor of a coaxial cable (not shown). Similarly, the outer conductor extension  34  is configured to be mounted in electrical contact with the outer conductor of a coaxial cable (not shown). The free end portion  46  of the outer conductor extension  34  is bevelled to facilitate insertion of the jack  130 . The outer conductor extension  34  also includes a radially-extending shoulder  40  with a bearing surface  42  that faces the jack  130 . The outer conductor extension  34  also includes a recess  44  on its radially-inward surface that provides a surface  48  that faces the jack  130 . The dielectric spacer  36  (which is annular in shape) is positioned between the central conductor extension  32  and the outer conductor extension. 
         [0028]    Referring again to  FIG. 1 , the jack  130  includes a central conductor extension  132 , an outer conductor extension  134 , and a dielectric spacer  136 . The central conductor extension  132  is configured to be mounted to and in electrical contact with the central conductor of a second coaxial cable. The central conductor extension  132  is hollow at its free end, forming a cavity  132   a  with a bevelled end  132   b . The outer conductor extension  134  is configured to be mounted to and in electrical contact with the outer conductor of the aforementioned second coaxial cable. The outer conductor extension  134  includes an outer body  138  with a free end portion  140 . The free end portion  140  includes a bearing surface  142 . The outer conductor extension  134  also includes an inner body  144  that is positioned radially inwardly from the outer body  138  and abuts the dielectric spacer  136 . Fingers  146  extend away from the inner body  144  toward the plug  30 , such that a gap  148  is formed between the fingers  146  and the free end portion  140  of the outer body  138 . The dielectric spacer  136  is positioned between the central conductor extension  132  and the outer conductor extension  134 . 
         [0029]    An O-ring  152  is located within an annular recess  35  in the outer conductor extension  34  to provide a seal to the interface when the plug  30  and jack  130  are mated. Also, a coupling nut  60  is captured by the shoulder  40  of the outer conductor extension  34  and mates with threads  138   a  on the outer body  138  of the outer conductor extension  134  to secure the mated plug  30  and jack  130 . 
         [0030]    Referring still to  FIG. 1 , when the plug  30  and jack  130  are mated, the post  32   a  is inserted into the cavity  132   a  to establish an electrical connection therebetween. Also, the free end  46  of the outer conductor extension  34  is inserted into the gap  148  of the outer conductor extension  134  to establish an electrical connection therebetween. More specifically, electrical connection is established between the fingers  146  of the inner body  144  and the radially inward surface of the free end portion  46  of the outer conductor extension  34 . The gap  148  and free end  46  are sized such that insertion of the free end  46  therein causes the fingers  146  to flex radially inwardly, thereby exerting radially outward pressure on the inner surface  48  of the free end portion  46  to establish an electrical connection. 
         [0031]    Notably, when the plug  30  and jack  130  are mated, the bearing surface  142  of the free end  140  of the outer body  138  contacts the bearing surface  42  of the shoulder  40  of the outer conductor extension  34 , but does not contact the coupling nut  60 , which is prevented from further movement toward the jack  130  by the shoulder  40 . As can be seen in  FIG. 1A , this arrangement causes a gap g 1  between the coupling nut  60  and the free end  149  of the outer body  138 , such that the mechanical “stop” (sometimes called the “mechanical reference plane”) is created by the bearing surface  142  and the bearing surface  42 . As a result, and as can be seen in  FIG. 1 , a small gap g 2  exists between the free ends of the fingers  146  and the surface  49  of the recess  44  of the outer conductor extension  34 . The presence of this gap g 2  indicates that electrical contact between the fingers  146  and the free end portion  46  of the outer conductor extension  34  is established by radial, not axial, contact between these components, and that the “electrical reference plane” created by such contact is offset from the mechanical reference plane described above. This arrangement is consistent with the specifications set forth for 4.3/10 interfaces. 
         [0032]    However, such an arrangement may also be subject to increased Passive Interconnection Modulation (PIM), which is a form of electrical interference/signal transmission degradation that may occur with less than symmetrical interconnections and/or as electro-mechanical interconnections shift or degrade over time. Interconnections may shift due to mechanical stress, vibration, thermal cycling, and/or material degradation. PIM can be an important interconnection quality characteristic, as PIM generated by a single low quality interconnection may degrade the electrical performance of an entire RF system. 
         [0033]    The lack of axial compression at the electrical reference plane is a potential PIM generator. The radial flex of the fingers of the outer conductor is unsupported by any secondary member that can help to stabilize the structure. Also, low coupling nut torque and solely radial compression may allow micro-movement of the fingers  146  during dynamic loading (e.g. wind, vibration, etc) that will degrade PIM performance. 
         [0034]    To address these potential shortcomings, an alternative configuration, comprising a plug  230  and a jack  330  and designated broadly at  200 , is shown in  FIGS. 2 and 2A . Much of the structure of the plug  230  and the jack  330  is similar to that shown in  FIG. 1 . Accordingly, the components in  FIG. 2  use the same numbering scheme as is used in  FIG. 1 , except that “200” is added to each reference number in  FIGS. 2 and 2A , in many cases, the components in  FIG. 2  are identical to their corresponding components in  FIG. 1 . The discussion that follows focuses on the differences between the connectors of  FIGS. 1 and 1A  and the connectors of  FIGS. 2 and 2A . 
         [0035]    As shown in  FIG. 2 , the outer conductor extension  234  of the plug  230  includes a projection  250  that extends radially inwardly from the surface  248  of the recess  244 , and a portion of the outer conductor extension  234  is receded from the projection  250  to form a gap g 3  (the portion of the outer conductor extension  234  that is receded from the projection may be provided as a separate component  251  as shown in  FIG. 2A ). Also, the surface  247  of the shoulder  240  that serves as a bearing surface for the plug  230  is receded somewhat from its position in the plug  30 . Further, in its relaxed condition, the inner body  344  of the outer conductor extension  334  of the jack  330  does not abut the dielectric spacer  336 , but instead includes a radially-extending flex section  339  that is spaced from the dielectric spacer  336  to which the fingers  346  are mounted. 
         [0036]    As can be seen in  FIGS. 2 and 2A , when the plug  230  is mated in axial engagement with the jack  330 , such that the free end  246  of the outer conductor extension  234  enters the gap g 1 , the fingers  346  of the inner body  339  contact the surface  248  of the recess  244 , but also contact the projection  250  of the outer conductor extension  234  prior to any contact between the free end portion  342  of the outer body  338  of the outer conductor extension  334  with the surface  242  of the shoulder  240 . The mated configuration “bottoms out” when the projection  250  flexes to the other side of the gap g 3  and the flex section  339  contacts the dielectric spacer  336 . Even when “bottomed out,” the free end portion  342  of the outer body  338  of the outer conductor extension  334  does not axially engage the surface  242  of the shoulder  240 . Thus, the mechanical reference plane is established at the contact point between the free ends of the fingers  346  and the projection  250 . Because either or both of the projection  250  and the flex section  339  can deflect or flex in response to such contact, an axial component to the electrical connection between the outer conductor extensions  234 ,  334  is provided as well as the radial component provided by the fingers  346  on the recess  244  of the outer conductor extension  234 . As a result, the mechanical and electrical planes are substantially coincident. 
         [0037]    The configuration illustrated can enable each reference plane (in the plug and jack) to be axially compressible (possibly as much as 0.5-0.8 mm in each interface). Therefore, axial misalignment is still allowed, which can facilitate easy gang mating for several connectors. Axial compression of the outer conductor extensions  234 ,  334  is accomplished while maintaining radial compression. This combined loading of the outer conductor extensions  234 ,  334  may improve PIM performance over radial compression alone, as the system may be stabilized by this collective loading. 
         [0038]    Those of skill in this art will appreciate that, in some assemblies, only one flex member may be present, and that the flex member may be included in either of the plug  230  or the jack  330 . 
         [0039]    Another configuration of a plug  430  for mating with the jack  330  is shown in  FIG. 3 . The plug  430  varies from the plug  230  discussed above in that the projection  250  is replaced with a generally U-shaped flex member  452  having a radially-extending flex section  454  attached to the outer conductor extension  434 , a body  456  and a stop  458  at the free end of the body  456 . The stop  458  has a bearing surface  459  against which the fingers  346  of the jack  330  abut at mating. The presence of the flex section  454  enables the body  456  and stop  458  to slide axially or flex in response to contact from the fingers  346 , thereby providing axial and radial compression for electrical contact as well as providing for potential axial misalignment as discussed above. 
         [0040]    Further variations of connectors according to embodiments of the present invention are shown in  FIGS. 4-7 . A plug  530  is shown in  FIG. 4 , a mating adapter  630  (analogous to the jacks discussed above) is shown in  FIG. 6 , and the mated plug  530  and adapter  630  are shown in  FIG. 7 . 
         [0041]    The plug  530  includes a central conductor extension  532 , an outer conductor extension  534  with an insert  535 , and a dielectric spacer  536 . The central conductor extension  532  is similar to that described above, with a generally cylindrical post  532   a  with a conical free end and a body  532   b  configured to be attached to the inner conductor of a coaxial cable. 
         [0042]    The dielectric spacer  536  is generally annular, but has a stepped profile, with a larger ring  580  and a smaller ring  582 . The smaller ring  582  fits over the central conductor extension post  532   a . The larger ring  580  fits inside the outer conductor extension  534 . The shape of the dielectric spacer  536  can be advantageous during the soldering of the outer conductor of the attached coaxial cable to the outer conductor extension  534 ; this process is described in International Application No. PCT/CN2014/071971, filed Feb. 11, 2014, the disclosure of which is hereby incorporated herein in its entirety. 
         [0043]    The outer conductor extension  534  is configured much like the outer conductor extension  234  discussed above. The outer conductor extension  534  has a shoulder  540  that provides a bearing surface  548  that receives the coupling nut  560  and an opposed surface  542 . The free end portion  546  of the outer conductor extension has an inner surface  547  with a shallow recess  549  adjacent a projection  550  that extends radially inwardly. One surface of the projection  550  bears axially against the larger ring  580  of the dielectric spacer  536 . 
         [0044]    The insert  535  (see  FIG. 5 ) is generally annular and includes a body  562  with a rim  563  on one end. Fingers  564  extend axially from the body  562  and terminate with radially outwardly-extending nubs  565 . As can be seen in  FIG. 4 , the rim  563  fits within the recess  549  of the outer conductor extension  534 , with the nubs  565  of the fingers  564  contacting the inner surface  547  of the free end portion  546 . 
         [0045]    Referring now to  FIG. 6 , the adapter  630  includes an inner conductor extension  632  similar to the inner conductor extension  132  discussed above, with the exception that the end  632   b  has fingers  632   c . The outer conductor extension  634  is similar to the outer conductor extension  234  above; it includes a free end portion  640 , but also includes an separate flex section  639  with fingers  646  that form a gap  648  with the free end portion  640 . A dielectric spacer  636  separates the inner conductor extension  632  from the outer conductor extension  634 . 
         [0046]      FIG. 7  shows the plug  530  mated with the adapter  630 . The free end portion  546  of the outer conductor extension  534  fits within the gap  648  between the fingers  646  and the free end portion  640  of the outer conductor extension  634 . The fingers  646  deflect to receive the free end portion  546 , thereby providing radial contact therebetween. Also, the ends of the fingers  564  of the insert  535  abut the ends of the fingers  646  to provide axial contact, which can cause either or both of the fingers  564 ,  646  to flex or bow slightly. As with the plug  230  and jack  330 , there is a gap g 4  between the end of the free end portion  640  of the outer conductor extension  634  and the shoulder  540  of the outer conductor extension  534  as prescribed by 4.3/10 interface guidelines, but both radial and axial contact between the outer conductor extensions  534 ,  634  are present to enhance electrical performance. 
         [0047]    The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.