US 3594687 A
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Description (OCR text may contain errors)
United States Patent Inventor Donovan C. Alderl'er Lansdale, Pa.
Appl. No 811,489
Filed Mar. 28, I969 Patented July 20,1971
Assignee Jerrold Electronics Corporation Philadelphia, Pa.
CONNECTOR FOR COUPLING A COAXIAL CABLE TO A PRINTED CIRCUIT BOARD OR THE LIKE 4 Claims, 6 Drawing Figs.
U.S.Cl .1 339/14, 339/17, 339/125, 339/177 lnt.Cl ..H0lrl1/28, HOlr 15/14 Field oiSearch ..339/125. 89
 References Cited UNITED STATES PATENTS 2,755,451 7/1956 Smyers 339/177 3,076,158 1/1963 Edelman A 339/177 X 3,496,515 2/1970 Painter, Sr 339/177 X FOREIGN PATENTS 603,919 8/1960 Canada 339/177 Primary Examiner-Richard E. Moore Attorney-Sandoe, Hopgood & Calimafde ABSTRACT: A device for coaxial cable connection to a planar circuit is described. A receptacle having a suitable bore is provided at one end with ears which project into apertures of a circuit board. The ears protrude through the circuit board for electrical grounding of the receptacle. The ears provide a rotational lock of the receptacle to therewith permit a firm stable connection to a coaxial cable at the other end of the receptacle CONNECTOR FOR COUPLING A COAXIAL CABLE TO A PRINTED CIRCUIT BOARD OR THE LIKE This invention relates to the connection of a coaxial cable to a circuit. More specifically, this invention relates to a connector for coupling a coaxial microwave cable to a printed circuit board.
In the connection of coaxial cables to planar microwave circuits, such as strip lines and the like, it is important to preserve a good electrical impedance match between the cable and the planar circuitry. Generally, the coaxial cable approaches the planar mounted circuit from a direction which is substantially transverse to the plane of the circuit. The latter electrical connection is difficult to make with low voltage standing wave ratios (VSWR). In addition, it is recognized that planar mounted circuitry does not tolerate strong mechanical forces. Mechanical forces either tend to dislodge discrete mounted components or cause a separation of conductors. When a microwave coaxial cable is connected -to a planar circuit board, the mounting of the cable usually involves rotational forces which are detrimental to the circuit elements. Accordingly, a proper tightening of the cable connection is not possible lest expensive complicated and bulky fastening arrangements are provided. Bulky cable fasteners generally are incompatible with strip line microwave circuits because of increased VSWR and loss of the desired miniaturization of the microwave circuit.
It is therefore an object of this invention to provide a connector for coupling a coaxial cable to a circuit board which is locked against rotational movement and provides excellent impedance matching.
It is a further object of this invention to provide a network for coupling a circuit board mounted planar circuit to a coaxial cable in a physically strong and electrically high-quality manner.
It is a further object of this invention to provide a small, economic and easily applied connector for interconnection of a planar circuit to a coaxial cable.
The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will best be understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, the description of which follows.
FIG. 1 is a perspective view of a final circuit assembly utilizing the invention;
FIG. 2 is a perspective exploded view of a circuit board utilizing the invention;
FIG. 3 is a plan view showing the connector of this invention as it is mounted relative to the circuitry on a circuit board;
FIG. 4 is a perspective view of a circuit board employing the connector of this invention;
FIG. 5 is a partial cross-sectional view taken along the line 5-5 in FIG. 4; and
FIG. 6 is a partial sectional view of another connector according to this invention.
Briefly stated, my invention contemplates an electrically conductive coaxial cable-receiving receptacle having a coaxial cable-receiving end and a circuit board mounting end which mounts substantially flush with the circuit board. The receptacle is provided with a through bore and ears projecting from the receptacle past the circuit board end thereof to protrude into apertures of the circuit board. The ears provide the dual function of positive locking of the receptacle against rotational movement and enabling electrical contact with a circuit on the board.
With reference to FIG. I, I show a housing I0 which contains an electrical network such as, for instance, a microwave hybrid junction circuit. Such hybrid junction circuit permits one to couple a coaxial cable to other coaxial cables with a minimum of loss and good impedance matching. For this reason, three coaxial cables I2, 12 and 12 may be connected to the housing 10 with two of the cables 12 and 12" illustrated to be connected to female connector 14' and 14'. The coaxial cables are of the standard 50 ohm or 75 ohm type and include a center conductor and an external outer conductor (not shown). The coaxial cables are provided with male connectors l6, 16" for connection to the receptacles by use of screw threads or a bayonet-type connection.
The housing 10 is provided with apertures such as I8 into which female connector 14 is mounted with the aid of a lockwasher 20. The connector 14 is screwed into a receptacle 32 which, in accordance with this invention, is mounted to a circuit board located below the aperture. As can be seen in FIG. I, the female connector 14 includes a flange 24 which seats on the housing 110, a screw-threaded outer conductor shoulder 26 and an inner conductor stud 28 which protrudes below shoulder 26 for electrical connection to circuitry on the circuit board in the housing 110. The stud 28 is in electrical connection with the center conductor of a coaxial cable connected to connector 14.
FIG. 2 illustrates the contents of the housing, i.e. a circuit board 30 and coaxial cable-receiving receptacles 32, 32', 32" for retaining the coaxial cable in contact with the circuitry mounted on the reverse side of board 30.
Note that the apertures 18, 18', I8" in the housing are in registration with the three receptacles 32, 32', 32". When completely assembled, the coaxial cable-receiving receptacles are affixed to the circuit board 30 and the entire circuit board assembly is held to the housing 10 by means of the female connectors 14, I4, I4". It should be realized that the external diameter of the coaxial cable-receiving receptacles 32. 32', 32" is slightly larger than the apertures l8, 18', 18" in the housing 110. The receptacles 32, 32' and 32" are shown cylindrically shaped but may have other external shapes as desired.
The coaxial cable-receiving receptacle is provided at its circuit board mounting end 34 with a plurality of ears such as 36 (one of which only is visible in the view of FIG. 2). The ears 36 fit into circuit board apertures 38 which flank a stud-receiving aperture 40. The stud aperture 40 is sized to receive the stud 28 of the female connector 14. The penetration of the ears 36 into the apertures 38 of the circuit board effectively rotationally locks the receptacle 32, thus permitting the female connector 14 to be firmly connected to the circuit board without disturbing circuitry thereon.
ln FIGS. 3 and 4, the ears of the receptacle are shown within the apertures 38 of circuit board 30. Note that the circuit board 30 is provided with a planar mounted electrical interconnection circuit comprising a ground conductor plane 42 surrounding but insulatively spaced from an active conductor 44. The active conductor 44 is connected to an active conductor plane 46 which in turn is coupled to the hybrid interconnection circuitry. The active conductor 44 is a flexible lead for soldered connections to the stud 28 of the female connector 14 when the stud 28 protrudes through the aperture 40. Note particularly that the apertures 38 in the ground conductor are in registration with the ears 36 and are so sized relative to the ears that little free play is encountered when the receptacle 32 is placed on the circuit board 30. This close fitting is desirable both to permit frictional retention of the receptacle during the assembly of the circuit board and to assure a positive rotational locking of the receptacle without rotational play. The ears 36 in the view of FIG. 4 are shown soldered to the ground plane 42.
The electrical network used with the receptacle 32 may include for instance a resistive element 48 which connects to a variable element 50 such as a capacitance or inductance for proper electrical tuning of the circuit. The ears 36 protrude through apertures with the stud aperture 40 located midway between them. It should be realized that additional ear apertures may be used when this is found desirable. For good electrical connection between the ground plane 44 and the receptacle 32, additional ears would enhance the electrical connecthe use of a pair of cars suffices.
In reference to FIG. 5, the interrelation of the circuit board 30 and the receptacle 32 with the female connector 14 is clearly shown. The stud 28 protrudes for interconnection to the lead 44 and the receptacle 32 is shown with its pair of ears 36 soldered to the ground conductor 44 on the circuit board 30. Note how the coaxial cable-receiving end of the receptacle 32 fits to the housing and how the circuit board assembly is retained by the female connector in cooperation with its flange 24 and the lock washer 20.
With further reference to FIG. 5, it may be appreciated that the use of the receptacle 32 effectively advances the coaxial line up to the plane on which the circuit is connected to the circuit board 30. The proximity of the coaxial line to the circuit enhances the impedance matching and substantially reduces the magnitude of the VSWR. Furthennore, a coaxial cable may be firmly attached without fear that electrical soldering connections are loosened.
In FIG. 6, I show a receptacle 52 which is cylindrical and has a bore extending between its coaxial cable-receiving end and the end adjacent the circuit board 30. In this particular embodiment, the bore of the receptacle is provided at a selected axial location with an annular shoulder 54 for the direct seating of a coaxial cable 12. The section of the bore between the shoulder 54 and the coaxial cable-receiving end is provided with a screw thread 56 for engagement with a cableclamping ring 58. The coaxial cable includes, as is conventional, an inner conductor 60 and an outer conductor 62 with an annular dielectric material 64 therebetween. The inner conductor 60, the dielectric material 64 and the outer conductor 62 are prepared in the manner shown whereby the outer conductor has an annular protruding portion in contact with the annular shoulder 54. The ring 58, upon engagement with the thread 56 within the bore, forces the outer conductor 62 against the shoulder 54, thus assuring a good ground connection between the coaxial cable outer conductor and the receptacle 52. To enhance the electrical connection between the receptacle and the outer conductor cable, both axial sides 66 and 68 of the shoulder are conically shaped, generally in correspondence with a like-shaped tip surface ofa drill. The conical shaping of the shoulder adjacent the circuit board end of the receptacle enhances the electrical matching capability of the cable to the circuitry on the circuit board. One noteworthy accomplishment of the receptacle of FIG. 6 resides in the simplicity of mounting of the coaxial cable as well as the mechanically rigid and secure connection. The electrical improvement enhances the utility of the receptacle of this invention.
While the principles ofthe invention have been described in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention as set forth in the objects thereof and in the accompanying claims.
1. A connector for coupling a coaxial cable having a central conductor and a threaded outer conductor shield surface insulated from said central conductor to a circuit board having an opening formed therein for receiving the central conductor and a pair of apertures adjacent said opening and a ground plane conductor formed on the board surface, said connector comprising an electrically conductive coaxial cable-receiving receptacle having a coaxial cable receiving end and a second end substantially flush mounted to the circuit board, a cylindrical conducting housing having an axial bore extending therethrough between said receiving end and said second end, said housing having a threaded internal periphery for threadably engaging the outer conductor of the coaxial cable, said receptacle including at said circuit board mounting end a pair of angularly spaced ears axially extending from the inner end of said housing past said flush mounting end into the circuit board apertures, said ears projecting through the circuit board to lock the receptacle against rotational movement with respect to the board, and means for electrically connecting said ears to the printed circuit board ground plane.
2. The device as recited in claim 1 wherein said ears face one another across the bore.
3. The device as recited In claim 1 wherein the receptacle bore is further provided with an annular apertured shoulder for seating of a coaxial cable and wherein the shoulder aperture is sized to receive the central conductor and dielectric insulator ofa coaxial cable.
4. The device as recited in claim 3 wherein the annular shoulder at its axial ends is conically shaped to enhance impedance matching ofthe receptacle.