Abstract:
Disclosed is a coaxial connector consisting of a back nut, outer and inner terminals, and an insulator. The back nut is made of a single tubular piece and does not enclose any further parts. In connecting a coaxial cable to the connector, the cable is inserted through the back nut, and a portion of the outer conductor at the end of the cable is flared and shaped along a tapered clamping face of the back nut. The back nut is then axially displaced, as by threading the back nut over the outer terminal, to clamp the flared end of the outer conductor of the coaxial cable between the outer terminal of the connector and the back nut thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of priority under 35 U.S.C. 517 365(a) of International Patent Application Ser. No. PCT/DK03/00473 filed on Jul. 4, 2003, designating at least one country other than the United States of America.  
   TECHNICAL FIELD 
   The present invention relates generally to a connector for coaxial cables and more particularly to a simplified coaxial connector and method of attachment of a cable to the coaxial connector. 
   BACKGROUND OF THE INVENTION 
   Current connectors on the market consist of a number of moving parts, typically a standard front end which consists of an inner terminal, an outer terminal, insulator and a moveable back nut which encapsulates a number of seals, retaining rings and the like. U.S. Pat. No. 6,133,532 shows one such connector, having a back nut which encapsulates three different moving parts (a locking device, guide surface and inner sleeve) as well as three separate O-ring seals. The large number of moving parts in the back nut portion complicates the fitting of a coaxial cable which usually requires the use of several specialized tools. Additionally, the risk of connector malfunctioning and mounting problems increases with a higher number of moving parts, since there is a greater chance that at least one part may be defective, missing or incorrectly attached. 
   Furthermore, due to the large number of moving parts encapsulated in the back nut of most conventional connectors, the outer conductor must be thoroughly cleared of all glue and adhesive material that may hinder or jam the parts during mounting and tightening, or a poor electrical connection may result. This process can prove to be quite difficult and time-consuming. 
   The manufacture and assembly of conventional connectors is also expensive in terms of time taken and material costs due to the number of parts enclosed in the back nut, which have to be manufactured and assembled. 
   Accordingly, it is an object of the present invention is to provide a simple, yet effective method of securely connecting a coaxial cable with either a corrugated or non-corrugated outer conductor to a coaxial connector. 
   A further object of the invention is to provide an economic and effective connector for coaxial cables. 
   A further object is to provide a connector having a simple design and a limited number of parts, thus reducing manufacturing expense and assembly time. 
   These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds. 
   SUMMARY OF THE INVENTION 
   The present invention provides a connector consisting of a back nut, inner and outer terminals, and insulator. The back nut is made of a single tubular piece and does not enclose any further parts. In connecting a coaxial cable to the connector, the cable is inserted through the back nut, and a portion of the conductor at the cable&#39;s end is flared and shaped along the back nut. The back nut is then axially displaced to clamp the cable between an outer terminal of the connector and the back nut. This process is very simple and easy to carry out, while greatly reducing the chances of errors and defects in assembly and mounting in comparison to convention connectors. 
   The reduction in the number of parts also means that only an end portion of the outer conductor which comes into contact with the connector has to be stripped of glue and adhesive material. This is a much smaller area than required for conventional conductors. 
   According to one embodiment, the procedure for mount the connector to the cable includes the steps of a) removing the insulating jacket from the end of the cable which is to be connected; b) removing the dielectric material from the end of the cable to be connected; c) inserting the cable through the back nut; d) stripping any adhesive material from the portion of the cable&#39;s outer conductor; e) shaping the cable&#39;s outer conductor to conform to the back nut&#39;s inside circumference; f) placing the outer conductor&#39;s stripped end portion in a gap formed between the outer terminal&#39;s contact face and the back nut&#39;s abutting face; and g) longitudinally displacing the back nut in relation to the connector&#39;s front end until the end portion of the cables outer conductor is clamped between the corresponding faces of the connector outer terminal and back nut. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of a connector, according to a preferred embodiment of the present invention. 
       FIG. 2  is a sectional view of the connector of  FIG. 1  mounted to a cable. 
       FIG. 3  is a view similar to  FIG. 2 , enlarged to show the attachment between an outer conductor portion of the cable and connector. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates an embodiment of a connector  10  having an outer terminal  4 , insulator  2  and inner terminal  1 , which are rigidly attached to one another, and a back nut  3 , which is rotatable and longitudinally displaceable along outer terminal  4 , via mating threads  21 . The inner terminal, back nut, and outer terminal are preferably made of brass. Other suitable materials include bronze for the inner terminal and plastic for the back nut. The insulator is press fit around the inner terminal and press fit into the outer terminal. 
     FIG. 2  illustrates connector  10  mounted to an end  19  of a cable  5 , which includes inner and outer conductors  11  and  12 , respectively, separated by a dielectric  13  and an outer insulating jacket  14 . Outer conductor  12  is rigid, and may either be corrugated or smooth. An air space  18  is created between outer surfaces of the inner terminal and insulator, and inner surface of the outer terminal, and the end of the cable. This air space minimizes the loss through the connector at the connection between the connector and the cable, and provides about one-third the loss obtained with connectors having a corresponding dielectric filling. 
   In preparing cable  5  for mounting, a portion of the insulating jacket is removed from the end of the cable to expose a portion  7  of the outer conductor. A portion of the dielectric is then removed to expose a portion  15  of the cable&#39;s inner conductor. Also, the exposed outer conductor portion  7  is stripped and cleaned of any adhesive material that may have been used to secure the jacket about the outer conductor. 
   Connector  10  is shown with inner conductor portion  15  mounted and in contact with inner terminal  1 , while the cable&#39;s stripped and cleaned outer conductor portion  7  is positioned in a gap  16  formed between abutting faces,  8  and  9 , respectively, of the outer terminal  4  and the back nut  3 , respectively. The cable receiving portion of the back nut, corresponding to face  9  is solid, not containing any slots or holes, in order to form a complete seal and make complete contact with the cable. The outer conductor portion  7  has been flared outwardly to create an enlarged-diameter lip after the exposed end of the cable has been inserted through the central aperture of the back nut. Outward flaring of the outer conductor may be produced by using a flaring tool for enlarging the diameter of the exposed end of the outer conductor. This flared end, or enlarged-diameter lip stops back nut  3  from slipping off the end of cable  5  and enables outer conductor portion  7  to be clamped in gap  16 , as shown in the figure. The length of the flared portion of the outer conductor is preferably less than the diameter of the cable, and more preferably, less than half the diameter of the cable; ideally, the length of the flared portion is less than one-fourth the diameter of the cable. An O-ring  6  is located within an annular groove in the back nut. When back nut  3  is threaded over outer terminal  4 , O-ring  6  is compressed between faces  8  and  9  to ensure that moisture does not enter between outer terminal  4  and back nut  3 ; moisture ingress often interferes with reliable electrical contact within the connector. 
     FIG. 3  is an enlarged view of the connection between the outer terminal  4  and back nut  3  (for clarity, O-ring  6  is not shown). As shown in  FIG. 3 , the end portion of outer conductor  12  is stripped of its jacket  14 . As is also shown in  FIG. 3 , a portion of the dielectric material inside the coaxial cable has been removed to expose the inner surface of the outer conductor. As shown in  FIG. 3 , the end of outer conductor  12  has been flared to ensure that it may be inserted into the gap between corresponding faces  8  and  9 .  FIG. 3  shows end portion  7  of the outer conductor clamped between the back nut  3  and outer terminal  4 , more specifically, between corresponding faces  8  and  9 , ensuring a good mechanical connection, as well as a good electrical connection with the outer terminal&#39;s contact face  8 . End portion  7  is compressed between back nut  3  and outer terminal  4  along the faces  8  and  9 , which are angled, as shown in  FIG. 3 , such that the longitudinal displacement of the back nut toward the outer terminal (resulting from the tightening of back nut  3  over outer terminal  4 ) causes the outer conductor to be clamped. The frontmost portion of back nut  3  has internal threads formed therein; a corresponding portion of the outer terminal  4  has external threads formed thereupon for mating with the aforementioned internal threads of back nut  3 . 
   Cable  5  is mounted as follows: first, the cable jacket  14  and dielectric material  13  is stripped off of the end of the cable to be connected. The cable is then inserted through the central aperture of back nut  3 . The exposed end of outer conductor portion  7  is then flared outwardly to a diameter which exceeds the smallest inner diameter of back nut  3 , using the flaring tool described above. Any adhesive or glue remaining on the flared end of outer conductor portion  7  is removed. The end  19  of inner conductor  15  of the coaxial cable is then inserted into inner terminal  1  of the connector, while simultaneously bringing flared outer conductor portion  7  into proximity with face  8  of outer terminal  4 . Back nut  3  is then threadedly engaged over outer terminal  4  and screwed until there is a mechanical stop. The connector is now reliably secured to the end of the coaxial cable. 
   According to a second embodiment, the cable may be mounted without removing either the cable&#39;s jacket or dielectric. The steps for mounting, according to this method, are as follows: first, an end portion of the cable is inserted through back nut  3 . A tool is then used to pry the end portion of the cable&#39;s outer conductor away from the dielectric and flare it outwardly, as mentioned above. The inner conductor of the coaxial cable is then inserted into inner terminal  1  of the connector as described above, and back nut  3  is screwed over outer terminal  4  until there is a mechanical stop, leaving the end portion of the cable securely clamped between faces  8  and  9  of the outer terminal  4  and back nut  3 . The cable can be mounted according to this method as long as there is a sufficient contact between the outer conductor portion  7  and face  8  of outer terminal  4 . 
   According to a third embodiment, the cable is mounted by removing the dielectric within the exposed end of the coaxial cable, but not the cable jacket. This is a combination of the two previous embodiments. The steps for mounting the cable are as follows: first, a sufficient amount of dielectric material is removed from the end portion of the cable. The exposed end of the coaxial cable is then inserted through the central aperture of back nut  3 . The end of outer conductor portion  7  is again flared outwardly. The inner conductor  15  of the coaxial cable is then inserted into inner terminal  1  of the connector, as described above. The back nut  3  is then longitudinally displaced, as by screwing back nut  3  onto outer terminal  4 , so that the flared outer conductor and adjoined insulating jacket are clamped securely between the outer terminal&#39;s contact face  8  and the abutting back nut face  9 . 
   Those skilled in the art will note that the above-described connector is of extremely simple design and requires a minimal number of components. It will also be noted that the outer conductor of the coaxial cable is directly clamped between the outer terminal and back nut of the coaxial connector, without requiring additional clamp rings, collars or other like components. As a result of its simple design, the disclosed connector can be manufactured relatively inexpensively and may be installed to the end of a coaxial cable relatively quickly and reliably. 
   While the present invention has been described with respect to a preferred embodiment thereof, such description is for illustrative purposes only, and is not to be construed as limiting the scope of the invention. Various modifications and changes may be made to the described embodiment by those skilled in the art without departing from the true spirit and scope of the invention.