Patent Publication Number: US-8123556-B2

Title: Low profile compact RF coaxial to planar transmission line interface

Description:
STATEMENT OF GOVERNMENT INTEREST 
     This invention was made with United States Government support under Contract number N00024-02-05421 with the Department of the Navy. The United States Government has certain rights in this invention. 
    
    
     TECHNICAL FIELD 
     The present invention relates to RF coaxial to planar transmission line interfaces, and in an embodiment, but not by way of limitation, to a low profile compact RF coaxial to planar transmission line interface. 
     BACKGROUND 
     A typical commercial off the shelf (COTS) interface that is used to connect a coaxial cable to a printed wiring board is illustrated in  FIG. 1 . The COTS interface  100  includes a board mount jack  105  that couples to the printed wiring board  107 . The jack  105  includes a center conductor  110 , which serves as an electrical coupling agent to the printed wiring board. A transition piece  115  includes a center conductor transition piece  120 , which inserts into the center conductor  110 . The transition piece  115  includes another center conductor transition piece  125 , which includes a female portion to receive the center conductor  155  of a coaxial cable  130 . The interface  100  further includes a plug  135  that encases the two coupled coaxial connections in the interface  100 . The coaxial cable includes an outer insulator  140 , an outer conductor  145 , and an inner insulator  150 , all of which terminate at the outer housing portion of the interface  100 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross sectional view of a commercial off the shelf coaxial line interface. 
         FIG. 2  illustrates a cross sectional view of a low profile RF coaxial to planar transmission line interface. 
         FIG. 3  illustrates another cross sectional view of a low profile compact RF coaxial to planar transmission line interface. 
         FIG. 4  illustrates a cross sectional view of a low profile compact RF coaxial to planar transmission line interface with a coaxial cable inserted into the interface. 
         FIG. 5  illustrates another cross sectional view of a low profile compact RF coaxial to planar transmission line interface with a coaxial cable inserted into the interface. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein in connection with one embodiment may be implemented within other embodiments without departing from the scope of the invention. In addition, it is to be understood that the location or arrangement of individual elements within each disclosed embodiment may be modified without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, appropriately interpreted, along with the full range of equivalents to which the claims are entitled. In the drawings, like numerals refer to the same or similar functionality throughout the several views. 
       FIGS. 2 ,  3 ,  4 , and  5  illustrate in cross sectional view a low profile compact coaxial to planar transmission line interface  200 . The interface  200  is used to couple a coaxial cable to a printed wiring board. The interface  200  includes an interface block  205 . The interface block  205  includes a stepped opening  210 . The interface block  205  may include more than one stepped opening  210 . In the embodiments of  FIGS. 2-5 , the stepped opening has three steps  215 A,  215 B, and  215 C therein. A different number of steps could also be used in the stepped opening  210 . The interface block further includes a means to attach to a printed wiring board. In an embodiment, the means includes one or more grounding pins  220 . 
       FIG. 3  illustrates a cross sectional view of the interface  200  with an adapter  250  inserted into the interface block  205 . The adapter  250  includes an inner profile  255  and an outer profile  260 . The outer profile  260  includes a series of one or more steps. In the embodiment of  FIG. 3 , the outer profile of the adapter includes a series of four steps  262 A,  262 B,  262 C, and  262 D. While four steps are illustrated for the outside profile of the adapter in  FIG. 3 , other embodiments can include a different number of steps. The steps  262 A,  262 B,  262 C, and  262 D align and mate with the steps  215 A,  215 B, and  215 C of the stepped opening  210 . In the embodiment of  FIG. 3 , the step  262 D rests on the outside surface of the interface block  205 . Further in the embodiment of  FIG. 3 , the step  262 D is an outermost step of the outer profile  260  of the adapter  250 . The inner profile of the adapter  250  includes a first inner diameter  271 A and a second inner diameter  271 B, thereby forming a step  264 . The intersection of the first diameter  271 A and the second diameter  271 B forms the step  264  at the approximate midpoint of the adapter  250 . 
       FIGS. 4 and 5  illustrate a cross section of a coaxial cable  310  that is inserted in the interface block and adapter construct. The coaxial cable  310  is inserted into the adapter  250 , which is or has been inserted into the stepped opening  210  of the interface block  205 . In this manner, the stepped opening  210  and the adapter  250  provide a passageway for the coaxial cable  210  to connect to a printed wiring board (not shown in  FIGS. 2-5 ). Specifically, the passageway provided by the stepped opening  210  of the interface block  205  receives a center conductor  315  of a coaxial cable  310  that is inserted through the interface block  205  to the printed wiring board side of the interface block. In this manner, the center conductor  310  is inserted into and coupled to the printed wiring board. 
     The coax cable  310  includes an inner insulator  320 . The inner insulator  320 , when the coax cable  310  is inserted through the interface block  205  and into the printed wiring board, is positioned entirely within the interface block  205  and lies substantially flush with the outside surface of the interface block that faces the printed wiring board. The coaxial cable  310  further includes an outer conductor  325 . The outer conductor  325 , when the coaxial cable is inserted into the passageway of the interface block  205  and the adapter  250 , comes to rest on the step  264  formed by the first inner diameter and the second inner diameter of the adapter. The coaxial cable  310  further includes an outer insulator  330 , which when the coaxial cable  310  is inserted into the interface block and adapter interface, rests on the outside surface of the adapter  250 . 
     The portion  270  of the adapter  250  that protrudes from the interface block  205  comprises a low profile. The low profile permits a coaxial cable  310  that is inserted into the interface block and adapter unit to be positioned away from a perpendicular to the interface block (or a line parallel to the central axis of the stepped opening of the interface block and the central axis of the adapter). In an embodiment, this low profile results in a distance, between the printed wiring board and the point of an attached coaxial cable that is bent to parallel in relation to the printed wiring board, of approximately 0.400 inches. Because of this low profile of the interface block and adapter construct, the positioning away from the perpendicular can be obtained closer to the printed wiring board than the constructs of the prior art such as that illustrated in  FIG. 1 . 
     In the foregoing detailed description of embodiments of the invention, various features are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment. It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively. Moreover, the terms “first,” “second,” and “third,” etc., are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The abstract is provided to comply with 37 C.F.R.1.72(b) to allow a reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.