Abstract:
An adapter having a housing, a ground clip and an adapter subassembly all located in the housing. The adapter subassembly includes a proximal portion that can be coupled to a coaxial connector and a distal portion that can be coupled to a printed circuit board. A central conductor in the form of an elongated shaft that runs through the subassembly and has a ball contact end for contacting a conductor located on a printed circuit board and the elongated shaft is tapered in a region near the bal contact.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 10/114,897, filed Apr. 2, 2002, which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Various types of electrical card edge connectors exist, however, very few are optimized for RF performance. Known RF card edge connectors require solder connections or complicated mechanical connections between a coaxial transmission line and a trace on a printed circuit board or complicated grounding techniques. These types of connectors make it difficult to replace the connectors quickly and easily. In addition, some connectors do not have a universal coaxial connection that allows the connector to be used with a variety of different types of coaxial connectors. Also, some of these known connectors are not modular so they do not easily lend themselves to being used in an array.  
         [0003]     It is desirable to provide an adapter that does not require permanent couplings such as solder or tools to assemble the adapter to a printed circuit board so that the adapter can be easily and quickly replaced. In addition, it is desirable to provide an adapter that is modular so that it can be used singularly or in an array. Also, it is desirable to provide an adapter design that is independent of the coaxial connector interface so that various styles of coaxial connectors may be used with the adapter. In addition, it is desirable to provide an adapter that is simple to manufacture and inexpensive.  
       SUMMARY OF THE INVENTION  
       [0004]     According to a first aspect of the invention, there is provided a high frequency adapter for coupling a printed circuit board having a signal trace and ground, to a coaxial connector. The adapter includes a housing, a ground clip and an adapter subassembly. The housing is designed to be removably coupled to the printed circuit board. The ground clip is located in a rear inner portion of the housing. The adapter subassembly includes a contact having a proximal portion and a distal portion and an elongated shaft coupling the proximal portion to the distal portion wherein the distal portion is configured to mate with the coaxial connector and the proximal portion is configured to mate with the printed circuit board. The elongated shaft is tapered in the proximal portion and the proximal portion terminates in a ball contact. The ball contact slides over the trace on the printed circuit board and electrically couples the trace on the printed circuit board to the contact. An insulator surrounds the contact and a conductive cylindrical connector surrounds the insulator so that the contact is concentrically positioned within the conductive cylindrical connector.  
         [0005]     According to a second aspect of the invention, there is provided an adapter for coupling a printed circuit board to a coaxial connector. The adapter includes a housing and a center conductor. The housing has a first end and a second end, the first end of the housing is configured to be coupled to a standard coaxial connector, the second end of the housing has a printed circuit board receiving groove. The receiving groove is configured to slide over a portion of the printed circuit board. The center conductor is located within the housing and has a printed circuit board contacting end that slides over a conductive contact located on a first surface of the printed circuit board. The center conductor has a coaxial connector end opposite the printed circuit board contacting end and coupled thereto by an elongated shaft. The elongated shaft is tapered in a region remote from the coaxial connector and the coaxial contacting end is ball shaped. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a cross-sectional perspective view of a high frequency adapter according to a preferred embodiment of the present invention.  
         [0007]      FIG. 2  is a side view of a proximal portion of a central contact.  
         [0008]      FIG. 3  is a perspective view of a ground clip according to a preferred embodiment the present invention.  
         [0009]      FIG. 4  is a graph illustrating simulated return loss for an adapter used with a printed circuit board having a first thickness according to a preferred embodiment of the present invention.  
         [0010]      FIG. 5  is another graph illustrating simulated return loss for an adapter used with a printed circuit board of a second thickness according to a preferred embodiment of the present invention.  
         [0011]      FIG. 6  is a perspective view of a single barrel housing according to a preferred embodiment of the present invention.  
         [0012]      FIG. 7  is a perspective view of a double barrel housing according to a preferred embodiment of the present invention.  
         [0013]      FIG. 8  is a perspective view of a single barrel housing according to an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]      FIG. 1  is a cross-sectional perspective view of a high frequency adapter  10  according to a preferred embodiment of the present invention. The adapter  10  is used to couple a printed circuit board  12  and a coaxial connector (not shown). The adapter  10  includes a housing  14  that is designed to be removably coupled to the printed circuit board  12 . In addition, located in a rear inner portion  16  of the housing  14  is a ground clip  18 . Also included in the housing  14  is an adapter subassembly  20  that includes a contact  22 , an insulator  24  surrounding the contact  22  and a conductive cylindrical connector  26  surrounding the insulator  24 . The contact  22  has a proximal portion  28  and a distal portion  30  and an elongated shaft  32  coupling the proximal portion  28  to the distal portion  30 . The distal portion  30  of the contact  22  is designed to mate with a coaxial connector (not shown) and the proximal portion  28  of the contact  22  is designed to mate with the printed circuit board  12 . The elongated shaft  32  is tapered in the proximal portion  28  and the proximal portion of the contact  22  terminates in a ball contact  34 . When the adapter  10  is coupled to a printed circuit board  12 , the ball contact  34  slides over a trace  36  located on the board  12  to electrically couple the trace  36  to the contact  22 . The distal end  30  of the contact  22  can be electrically coupled to a coaxial connector (not shown). The adapter  10  thereby couples the printed circuit board  12  to a coaxial connector. The adapter  10  can be coupled to any type o coaxial connector such as a BNC connector or an F connector, for example.  
         [0015]     The tapered shape of the contact  22  allows the adapter  10  to reduce the impact of vibrations on the electrical connection between the contact  22  and the printed circuit board  12 . In addition, it is flexible while still maintaining an acceptable level of stability. The ball contact  34  provides tolerance flexibility that allows the adapter to be coupled to a printed circuit board  12  that is not completely parallel with the axis of the contact  22 .  
         [0016]     In a preferred embodiment, the housing  14  is made of plastic. The contact  22  is press-fitted into the insulator  24  and the insulator  24  is press-fitted in the outer cylindrical conductive connector  26 . The ground clip  18  is also press-fitted into the inner rear portion  16  of the housing  14 .  
         [0017]      FIG. 6  is a perspective view of a single barrel housing  140  according to a preferred embodiment of the present invention which houses a single adapter subassembly  20 .  FIG. 7  is a perspective view of a double barrel housing  240  according to a preferred embodiment of the present invention which houses a pair of adapter subassemblies  20 . Each housing  140 ,  240  has a front face  40  that has a pair of alignment pins  42  which fit into a panel (not shown) to properly align the housing  140 ,  240  with the panel. In the single barrel embodiment shown in  FIG. 6 , the pair of pins  42  are located on opposite sides of the barrel. In the double barrel embodiment shown in  FIG. 7 , one pin  42  is located on each barrel. Alternatively, the housing  140 ,  240  may be provided with holes  62  shown in  FIG. 8  in place of the alignment pins  42  and the panel, on which the housing is mounted, may have alignment pins that fit into the holes in the housing for alignment purposes.  
         [0018]      FIG. 2  is a side view of a proximal portion of the central contact  22  shown in  FIG. 1 . As previously described, the proximal portion  28  of the contact  22  has a tapered section  44  and terminates in a ball contact  34 . In a preferred embodiment, the ball contact  34  is elliptical in shape although it may have other shapes such as cylindrical, or oval, for example. The ball contact  34  has a central portion  46  and end portions  48  adjacent to the central portion  46 . The end portions  48  include a first portion that connects the ball contact  34  to the tapered portion  44  and a second portion opposite the first portion that defines the proximal termination of the contact  22 . The ball contact  34  is thickest at its central portion  46 .  
         [0019]      FIG. 3  is a perspective view of a ground clip  18  according to a preferred embodiment the present invention. The ground clip is a spring having an elongated flat section  50 , a first folded-over section  52  coupled at one end of the elongated flat section  50  and a second folded-over section  54  coupled at an opposite end of the elongated flat section  50 . The first folded-over section  52  has a free end  56  that rides over a portion of the second folded-over section  54  to provide a spring force to the ground clip  18  so that when the adapter  10  is coupled to the printed circuit board  12 , the ground clip  18  is compressed so that the elongated flat section  50  mates with a ground  60  shown in  FIG. 1  located on an underside of the printed circuit board  12 .  
         [0020]      FIG. 4  is a graph illustrating simulated return loss for an adapter used with a printed circuit board having a first thickness according to a preferred embodiment of the present invention for various trace widths. A simulation was run for a contact as shown in  FIG. 2  and a printed board thickness of about 0.062 inches. Return loss in decibels was plotted on the vertical axis and frequency in Megahertz was plotted along the horizontal axis. It can be seen from the graph that the simulated return loss is better than −30 decibels from dc to 2500 MHz.  
         [0021]      FIG. 5  is another graph illustrating simulated return loss for an adapter used with a printed circuit board of a second thickness according to a preferred embodiment of the present invention for various trace widths. A simulation was run for a contact as shown in  FIG. 2  and a printed board thickness of about 0.093 inches. Return loss in decibels was plotted on the vertical axis and frequency in Megahertz was plotted along the horizontal axis. It can be seen form the graph that the simulated return loss is better than −30 decibels from dc to 2500 MHz.  
         [0022]     The adapter has the advantage that it does not require permanent couplings such as solder or tools to assemble the adapter to a printed circuit board so that the adapter can be easily and quickly replaced. In addition, the adapter is modular so that it can be used singularly or in an array. The adapter design is also independent of the coaxial connector interface so that various styles of coaxial connectors may be used with the adapter.  
         [0023]     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.