US 3336563 A
Description (OCR text may contain errors)
ug. i5, H967 R. K. HYsLoP 3,336,563
COAXIAL CONNECTORS Original Filed April 13, 1964 25 27 33 37 'f b[45 2s United States Patent O 3,336,563 CUAXIAL CONNECTORS Raymond K. Hyslop, Newtown, Conn., assigner to Amphenol Corporation, a corporation of Delaware Continuation of application Ser. No. 359,133, Apr. 13, 1964. This application Dec. 5, 1966, Ser. No. 599,673 Claims. (Cl. 339-61) This is a continuation of application Ser. No. 359,133, tiled Apr. 13, 1964, and now abandoned.
This invention relates to coaxial electrical connectors and especially to coaxial electrical connectors adapted for use with radio frequency transmission lines of the coaxial type.
Among the features considered desirable in a coaxial electrical connector are (a) electrical characteristics which are not only constant but also uniform from connector to connector, such that the coaxial connector introduces the least possible discontinuity to the propagation of electrical signals therethrough, and (b) construction features which not only simplify the installation of the connector to a coaxial line but also result in uniform and adequate mechanical strength. The electrical characteristics of a coaxial connector are intimately related to its mechanical construction.
It is a principal object of this invention to provide a coaxial electrical connector capable of interconnecting the ends of radio frequency transmission lines with an electrical continuity through the connector so stabilized by the mechanical construction of the connector that the V.S.W.R. (Voltage Standing Wave Ratio) through the connector is not subject to appreciable variation due to minor changes of position or floating of the parts, regardless of the imposition of varying mechanical stresses on the connector or on the cables connected thereby, and regardless of the expansion or contraction of the component parts of the assembly due to temperature changes.
A further object of the invention is to provide improved coaxial connectors which, while having closely controlled mechanica-l and electrical characteristics as noted above, are nevertheless especially adapted to quick, convenient and reliable attachment to coaxial lines.
A more particular object of this invention is the provision of coaxial connectors employing factory completed subassemblies which reduce the number of loose components which must be finally assembled for attachment to coaxial lines and which may be completely assembled on coaxial transmission lines in an uncomplicated procedure to effect an electrically uniform and mechanically reliable line connection.
In addition to the reduction in the total number of components to be assembled in the eld, it is a further object of the invention to provide an improved coaxial radio frequency connector having a smal-l total number of parts, the construction o-f which facilitates the assembly of the connector partsy in such a manner as to maintain their precise and properly calculated electrical parameters, thereby bringing about a great uniformity in the electrical characteristics of the connectors.
The present invention contemplates the construction of the vital internal parts of coaxial connectors in a manner to minimize the possibility of minor internal movements or variations in position of component parts, either as to spacing or as to alignment, since such movements or variations might otherwise give rise to electrical discontinuities, particularly in the high frequency ranges. These internal parts, including especially a dielectric spacer and an internal contact, are constructed to be slipped easily together in an operation which in itself is noncritical, but which brings about precise and iirm relative orientations between the parts with little tendency toward misalignment. Although the invention provides for a profound departure from the typical practices and construction features heretofore employed in coaxial connectors, it should be pointed out that coaxial connectors designed and constructed in accordance with this invention are nevertheless compatible with prior types of connectors; that is, they are physically interchangeable with connectors of corresponding types heretofore commercially manufactured.
Although the scope of the invention is not to be limited except by the claims appended hereto, further details of the invention as Well as additional objects and advantages will be better comprehended in connection with the accompanying drawings illustrating a preferred embodiment of the invention wherein:
FIGURE l is an enlarged central cross-sectional view through a connector plug subassembly constructed according to the present invention and ready for attachment to a exible coaxial radio frequency transmission line;
FIGURE 2 is a view partially in elevation and partly in cross section of the end of a exible coaxial line stripped back in proper manner and with a central terminal attached thereto prior to assembly with the connector plug subassembly of FIGURE 1;
FIGURE 3 is a central cross-sectional view of the subassembly shown in FIGURE 1 after being joined to the prepared coaxial line of FIGURE 2;
FIGURE 4 is a cross-sectional view of a mating receptacle constructed in accordance with this invention and assembled with a radio frequency coaxial line for cooperative engagement with the plug illustrated in FIGURE 3.
The principles of the present invention, while of general application, will be described in connection with a connector designed to interconnect the ends of flexible coaxial radio frequency transmission lines of the type having a solid or stranded wire as the central conductor, surrounded by a dielectric, which is in turn enclosed by an outer conductor of Woven flexible Wire or metal ribbon braid and covered by a tough insulating sheath of suitable plastic or fabrics. Cables of this type are well known and quite conventional for transmission of radio frequency signals.
Referring now to FIGURE 1, the plug subassembly shown therein is seen to comprise a body portion 1G including a tubular metal shell 11 at the right end as seen in this illustration and at the left an integral cylindrical coupling sleeve 12 tapered to a thin feather edge 13 at its end. A central bore 14 extends axially through the coupling sleeve 12 and communicates with a larger diameter counterbored cavity 15 in which is positioned a cylindrical dielectric insert 16. The dielectric insert 16 is held in place in the counterbore 15 by a slight indentation 17 which may extend around the wall of the metal shell portion 11.
It is to be noted that the external configuration of the dielectric insert 16 is that of a circular cylinder lling counterbore 15 to the perpendicular shoulder 18 at the bottom thereof. Insert 16 has a central bore 19 which is axially aligned with the lcentral bore 14 in the body 10. At the left end of the central bore 19 as seen in this illustration is a slightly larger counterbore 20 dimensioned to receive the dielectric insulation of a coaxial line as will be explained further hereinafter. At the other end of the bore 19 in the dielectric insert 16 is another counterbore 21 which opens out into a still larger counterbore 22.
For attaching the connector plug thus far partially described to a mating receptacle, the assembly is provided with an outside rotary coupling collar 25 having a forwardly extending locking sleeve 26 and a knurled finger grip 27. The coupling collar 25 encloses an internal cylindrical chamber 28 dened by the space between the annular end wall 30 of the coupling collar 25 and the inwardly offset shoulder 31 at the edge of the forward cylindrical locking sleeve 26 which has a slightly reduced internal diameter. The lbody member and its included dielectric insert 16 are held loo-sely captive within the coupling collar 25, in this embodiment, by the confinement within chamber 28 of a washer 33 positioned in an annular slot 34 in the external flange 35 integral with the shell portio-n 11 of body 10. A spring washer 36 encircles the body portion 10 between the annular end wall 30 of the coupling collar 25 and the iiange 35 o-n shell 11. Surrounding the shell portion 11 on the forward side of flange 35 is a gasket 37 of compressible material.
The rotary locking sleeve 25 thus constitutes the forward end of the coaxial connector plug assembly and is capable not only of rotational movement about shell 11 but also of limited relative axial movement thereon. The forward end of the locking sleeve 26 on the coupling collar 25 is formed with cut-away channels 41, only one of which is visible in the cross-sectional view of FIG- URE 1. Channel 41 communicates with helically disposed grooves 42 which terminate in slightly enlarged apertures 43 in the locking sleeve to engage paired lugs on a bayonet plug to be inserted within the locking sleeve.
Turning now to FIGURE 2 there may lbe seen a coaxial radio frequency line 45 prepared for attachment to the a'bove described assembly. Prior to final assembly, a ferrule 44 is placed upon the coaxial line 45 and the line is stripped as shown by cutting back the insulating sheath 46, the metal braid covering 47, and the dielectric 4S in stepped fashion to expose the end of the inner conductor 49. A central connector contact 51 having a pin 52 at its forward end and a central bore 53 to receive the inner conductor 49 is then slipped over the end of the inner conductor 49 to abut against the line dielectric 48. The contact 51 is then affixed thereon, as by the application of liquid solder applied through a solder port 54 provided in the side of the contact and communicating with bore 53 for that purpose.
It is to be noted that the Contact member 51 is provided at a place intermediate its ends with an annular locking flange 55 having a conical cam surface 56 on its forward or leading edge and a sharp radially extending ridge or shoulder 57 on the opposite edge. The shape of the central contact 51 and its prior aixation to the conductor of the coaxial line 45, as will be seen, greatly simplifies the task of assembling the complete coaxial connector to the coaxial line.
The prepared end of the coaxial line as shown in FIGURE 2 is then attached to the plug subassembly shown in FIGURE 1 to create the assembly shownin FIGURE 3. This is accomplished by inserting the contact 51 and the dielectric 48 of the stripped end of the line 45 into the central `bore 14 in the coupling sleeve 12 until the dielectric layer 48 enters the counterbore 20 and seats against the dielectric insert 16 at the end of counterbore 20.
Simultaneously, the woven wire braid 47 of the coaxial transmission line, previously flared slightly as shown in FIGURE 2, is spread by the tapered edge 13 of the sleeve 12 and telescoped over substantially the entire length of the sleeve 12. The ferrule 44 is then drawn over the outside of the braid 47 until it abuts the slightly enlarged outwardly offset central portion of the body member, where it is preferably crimped in place by a standard crimping tool to clamp the expanded braid 47 against the outer surface of the sleeve 12. It is to be noted that while the braid layer 47 is somewhat loosened and expanded to fit cover the sleeve, it is not unraveled nor combed out and is clamped in braided condition thus effecting a strong uniform mechanical joint with good electrical conductivity.
When the central contact 51 enters the central bore 19 of the dielectric insert 16, the locking flange 55, which is larger in diameter than the bore 19, engages the sides of bore 19 and urges them outwardly. It is therefore important that the material of which the dielectric insert 16 is composed be suliiciently elastic to yield under the force of the advancing conical cam surface 56 during its passage through the dielectric material. The dielectric material of insert 16 should not rupture during the passage of the locking flange 55 therethrough, nor should it be abraded by the outer periphery of the locking ring. It should, in addition, have sufficient elasticity to return to substantially its original dimensions after the passage of the locking flange 55 therethrough. The elastic properties of the dielectric material should also be balanced by a sufficient degree of rigidity `to maintain the central contact S1 accurately centered within the dielectric sleeve 16.
For the material of dielectric insert 16, I prefer to employ a polypropylene composition currently available as Avisun Grade 1044, a semirigid composition possessing sufcient elasticity to snap back to its original dimensions after being subjected to the deformation described. As can be seen in FIGURE 3, the shoulder 57 of the radial locking flange 55 snaps through into the counterbored cavity 21 at the forward end of the central bore 19 to seat itself in firm locking engagement with the perpendicular shoulder at the base of counterbore 21. When this is accomplished, it can be seen that the coaxial line 45 is securely locked to the subassembly of sleeve 11 and dielectric spacer 16. The coaxial line 45 cannot be pulled back out of this subassembly because of the locking engagement between locking flange 55 and the base of the counterbore 21 in the dielectric insert 16. Neither can the coaxial line 45 be forced any farther into or through the subassembly because of the engagement by the dielectric insulation 48 of the coaxial line with the base of counterbore 20 in the dielectric insert 16.
It is to be noted that the precision with which inner contact 51 is centered and axially located within the dielectric insert 16 is a consequence almost entirely of the geometry of these two elements alone. The skill of the assembler is of little consequence to the precision of the nal assembly, since all that is necessary is rst to ensure that contact 51 is bottomed against the transmission line dielectric 48 before it is affixed by soldering or otherwise to the inner conductor 49 and then to insert the coaxial transmission line until the inner contact 51 snaps into and is locked in its final position.
It should also be noted that the heat of the soldering loperation involved in aflxing the central contact 51 to conductor 49 is applied before the contact is placed in proximity to the dielectric insert 16. The contact 51 is permitted to cool before it is inserted in the dielectric insert 16, and there is thus no possibility of heat damage to the dielectric insert of the connecting plug. Furthermore, when the prepared coaxial line as illustrated in FIGURE 2 is inserted into the subassembly of FIGURE l, the firm engagement between the dielectric 48 of the coaxial line and the dielectric 16 of the connector plug is accomplished without the use of additional threaded clamping elements. Nor is it necessary to rely upon cement solvents or adhesives to retain lthe dielectric elements in place.
In FIGURE 4 is shown a mating receptacle for the above described connector plu-g constructed and assembled in accordance with the same inventive principles. The receptacle includes an outer metallic shell member 60` of unitary rather than two-piece construction having a forward contact sleeve portion 61 with a pair of locking lugs 62 on an outer surface thereon, a sleeve 63 of reduced liameter at the opposite end of the shell member, and a knurled finger ring 64 intermediate the two ends. A central bore 65 extends axially through the shell member 60 opening out into a first counterbore 66 and beyond that into a slightly larger counterbore 67. Within the counterbore 66 is positioned a cylindrical dielectric insert 68 filling the counterbore 66 to the perpendicular shoulder 69 at the bottom thereof and held therein by a locking ring 70 wedged within an annular space between the base of counterbore 67 and an annular shoulder 71 Ion the dielectric insert 68. The dielectric insert 68 is preerably composed of the same kind of material employed in forming the previously described dielectric insert 16. rlhe shell member 60, the locking ring 7l] and the dielectric insert 68` thus constitute a receptacle subassembly to which coaxial line 45a is joined after an initial preparation.
As previously described in connection with FIGURES 2 .and 3, the coaxial line 45a is prepared by first cutting back the insulating sheath 46a, the metal Ibraid 47a and the dielectric insulation 48a in stepped fashion to expose the end of the central conductor 49a. An inner contact 72 having a conductor-receiving -bore 73 is then inserted over the exposed end of conductor 69a and affixed in place by applying liquid solder through a solder port '74 in the side surface thereof to the conductor 49a within the bore 73. The inner contact 72 is configured at its forward end to include a female contact portion 75 shaped to receive the central contact pin 52 of the FIG- URE 3 assembly therein. Intermediate its ends, the contact member 72 also includes a locking flange 76 having its forward or leading edge in the shape of a conical cam surface 77 and at its trailing edge an annular shoulder '78 extending slightly beyond the diameter of the contact member 72.
When the end of the prepared coaxial line 45a is inserted into the receptacle subassembly, the passage of the inner contact 72 through the axial bore 81 of the dielectric insert 68 is resisted because the diameter of the axial Ibore 81 is less than that of the locking liange 76. The conical cam surface 77 overcomes this resistance by urging the material of the dielectric insert 68 outwardly during its passage through the central bore 8l until it reaches the counterbore 82 at the forward end thereof and snaps into rm locking contact with the dielectric insert 68, whereupon the shoulder 78 of the locking flange 76 is seated securely against the base of the counter-bore 82. At this time the dielectric 48a of the coaxial line 45a abuts squarely against the dielectric insert 68 within the counterbore 83 at the rearward end of bore 81.
Simultaneously with the insertion of the central conductor 49a and the dielectric insulation 48a into the receptacle subassembly, the wire braid 47a, initially prepared by a slight flaring thereof, is slipped over the outside of sleeve 63 as in the previously described connector plug until it covers substantially the entire outer surface of the sleeve 63. A crimping sleeve 84 previously placed on the coaxial line 45a is then slipped o-ver the outside of the wire braid and crimped in place. If desired, an outer tubing 85 of a material which shrinks when heated may also be placed over the crimping sleeve 84 and shrunk in place thereon as shown in FIGURE 4. These simple operations complete the assembly of the receptaclev shown in FIGURE 4.
The receptacle of FIGURE 4 mates accurately with the plug of FIGURE 3. When the two assemblies are placed together end to end, the locking lugs 62 on the exterior surface of the contact sleeve 61 slip Within the slots 41 in the forward end of the coupling and collar 25 hence along the inclined channels 42 until the locking lugs 62 seat within apertures 43. At such a time -the ychamfered end 86 of the contact sleeve 61 is guided over the curved contact lip 87 at the forward end of sleeve 11 into the space between sleeve 11 and the locking sleeve 26 until the end of the contact sleeve 61 engages the gasket 37 and presses the shell 11 backward within the coupling collar 25 against the force of the spring `washer 36. The spring washer 36 thus assists in maintaining the locking lugs 62 within the apertures 43 to hold the two connector assemblies together.
V It will be appreciated, of course, that as the connectors are joined the forward end of the dielectric insert 68 telescopes within the counterbore 22'of the dielectric insert 16. The female contact portion of inner contact 72 also slips over the end of thecontact pin 52 of inner contact 51, thus completing an electrical connection between the central conductor 49 of the one coaxial cable and the central conductor 49a of the other cable. Electrical continuity between the metal braid sheaths of the two coaxial lines is established through the intertting connections of contact sleeves 11 and 61. When the two connector plugs are joined it will be noted that the telescoping dielectric inserts 16 and 68` constitute an essentially cylindrical two-piece dielectric insulation surrounding an inner twopiece conductor comprised of the contact pin 51 and the contact member 72.
This construction is to be contrasted with prior assemblies which have either required a `total of at least four dielectric inserts, i.e., two dielectric inserts in each connector section, or which, although employing a single dielectric insert in each connector section, have required the use of adhesives applied at the time of final assembly in order to hold the dielectric inserts within the structure. Those assemblies making use of a larger number of dielectric spacers or inserts invariably have required a substantially more complex assembly making use of multiple threaded clamping members. `On the other hand the simpler cemented assemblies, in addition to being dificult to assemble in the field, are generally not adaptable for use with many types of dielectric materials such as Teflon which do not lend themselves re-adily to cementitious bonding.
From the foregoing description it should be apparent that the principles of the present invention succeed in balancing the requirements for mechanical strength, electrical continuity, and simplicity of construction to result in connectors having advantages in all of these important respects. It is to be noted that the internal design of the connector parts is such that there is positive electrical union between the connector contacts and the transmission line conductors at all times. Also, the inner contacts of the connectors are positively held against lateral displacements in the bores of the dielectric inserts, and at the same time are confined in a manner to prevent axial shifting. This is important, as has been pointed out, in order to avoid changes in the radio frequency electrical characteristics of the connector in response to mechanical stresses.
It is an especially important feature that the prepared end of the coaxial line may be inserted and locked in the basic connector subassembly in one swift noncritical operation which brings about the precise spacing and absence of shifting of parts which are required in high quality connectors. The vital dimensions of the final assembly do not depend upon the skills or special care of the assembler and the danger that the parts might be incompletely or improperly assembled is considerably minimized. With all of these advantages it is also to be observed that the present invention provides a design concept for coaxial connectors which is well suited to modern high production methods of commercial manufacture.
While but one preferred embodiment of this invention has been shown and described, certain variations of construction within the scope of these teachings will doubtlessly occur to those skilled in the art to which the invention pertains, The appended claims are therefore intended to cover all such variations of construction as fall within the true spirit and scope of this invention in its broader aspects.
1. A connector assembly for providing constant electrical characteristics to coupled coaxial radio Ifrequency transmission lines of the type having a constant diameter inner conductor surrounded by a dielectric layer of uniform dielectric constant and a constant diameter tubular outer conductor, the assembly comprising:
an electrically conductive -body having a forward coupling portion of generally cylindrical form and a rearwardly extending tubular portion for connection to the outer conductor of a coaxial transmission line, said body having a cylindrical bore extending through said rearwardly extending portion and communicating concentrically with a cylindrical ycounterbore of substantially larger diameter in said coupling portion, said cylindrical counterbore terminating in a substantially perpendicular shoulder at the bottom thereof,
a dielectric sleeve positioned in and filling said counterbore to the bottom thereof, said dielectric sleeve having a central bore therethrough,
a central contact adapted to be permanently aflixed to the inner conductor of the coaxial transmission line and inserted into a predetermined assembled position inside the central bore of said dielectric sleeve, said contact having a forward contact portion adapted to receive a mating contact and further having a rearward socket portion adapted to be telescoped over a bare end portion of the inner conductor of the coaxial transmission line to abut the end of said dielectric layer thereof, said socket portion having an outer diameter dimensioned to fit closely within the central bore of said dielectric sleeve, said contact also being provided with an integral locking means for engaging said dielectric sleeve to positively secure said contact in the predetermined assembled position in order to prevent the radio frequency electrical characteristics of the connector assembly from appreciably varying due to minor changes of position of said contact.
2. A connector assembly for providing constant electrical characteristics to coupled coaxial radio frequency transmission lines of the type having a constant diameter inner conductor surrounded by a dielectric layer of uniform dielectric constant and a constant diameter tubular outer conductor, the assembly comprising:
an electrically conductive body having a forward coupling portion of generally cylindrical form and a rearwardly extending tubular portion for connection to the outer conductor of a coaxial transmission line, said body having a cylindrical bore extending through said rearwardly extending portion and communicating concentrically with a cylindrical counterbore of substantially larger diameter in said coupling portion, said cylindrical counterbore terminating in a substantially perpendicular shoulder at the bottom thereof,
a dielectric sleeve positioned in and filling said counterbore to the bottom thereof, said dielectric sleeve having a central lbore therethrough with counterbores at the rearward and forward ends thereof,
a central contact adapted to be permanently affixed to the inner conductor of the coaxial transmission line and inserted into the central bore of said dielectric sleeve, said contact having a forward contact portion adapted to receive a mating contact and further having a rearward socket portion adapted to be telescoped over a bare end portion of the inner conductor of the coaxial transmission line to abut the end of said dielectric layer thereof, said socket portion having an outer dia-meter dimensioned to tit closely within the central bore of said dielectric sleeve, said contact also being provided with an integral locking flange having an outer diameter greater than that of said socket portion, said contact and its locking flange being insertible unidirectionally into said dielectric sleeve through the central bore from the rearward end thereof until said locking flange passes through the central bore and emerges into locking engagement with the bottom of the counterbore at the forward end of said dielectric sleeve to prevent the radio kfrequency electrical characteristics of the connector assembly from appreciably varying due to minor changes of position of said contact.
3. The apparatus of claim 2` wherein said electrically conductive body and said dielectric sleeve are both of unitary construction.
4. The apparatus of claim 2 wherein said dielectric Sleeve is composed of a semirigid material having sufficient elasticity to deform during the passage of said locking flange through said central bore and to return to substantially its original internal diameter thereafter.
5. The apparatus of claim 4 wherein the end of the dielectric layer of the coaxial transmission line is positioned in and fills said counterbore at the rearward end of said dielectric sleeve in order to prevent forward changes of position of said contact.
6. The apparatus of claim 5 wherein said locking flange includes a tapered conical surface on the forward side thereof to permit the insertion of said central contact through the central bore of said dielectric sleeve.
7. A coaxial connector for providing constant electrical characteristics to coupled coaxial radio frequency transmission lines of the type having a constant diameter inner conductor surrounded by a dielectric layer and a constant diameter tubular center conductor, the assembly comprising:
mating halves consisting of a plu-g and a receptacle,
each including an electrically conductive body portion connectible to the conductive sheath of a coaxial transmission line and having a forward coupling portion of generally cylindrical form with internal counter-bores in the coupling portions of both said plug and said receptacle of substantially cylindrical form and substantially the same diameter disposed in end-to-end relation with each other when connected to define an internal cavity of substantially cylindrical shape with a concentric opening in the rearward end of each of said plug and receptacle a pair of tubular dielectric sleeves filling said cylindrical cavity in aligned relation when connected, with a central bore in each of said dielectric sleeves in alignment with the bore of the other, and
With a larger diameter counterbore at the mating end of each of said dielectric sleeves; and
a central connector terminal in each of said mating halves having a socket portion adapted to be telescoped over a bare end of the central conductor of a coaxial transmission line to abut the end of the dielectric layer thereof,
each of said connector terminals having a locking` means intermediate its ends of larger diameter than the central bores of said dielectric Sleeves for engaging an internal surface of the counterbore within its associated dielectric sleeve to restrain said connector terminals against rearward shifting in order to prevent the radio frequency electrical characteristics of the connector from appreciably varylng:
said connector terminals being insertible unidirectionally through the central bores of said dielectric sleeves until said locking means emerge into said dielectric sleeve counterbores,
said dielectric sleeves being formed of a semirigid composition having sufficient elasticity to deform outwardly during the passage of said locking flanges through the respective central vbores thereof and to return to substantially their original internal diameter after such passage to block the passage of said central terminals in a reverse direction therethrough.
8. The apparatus of claim 7 wherein each of said electrically conductive bodies and said dielectric sleeves are of unitary construction.
9. The apparatus of claim 8 wherein each of said dielectric sleeves further includes a counterbore at the rearward end thereof, the ends of the dielectric layer of the coaxial transmission line being positioned in and filling said counterbores at the rearward ends of said dielectric sleeves to prevent changes of position of said contact in one direction.
10. The apparatus of claim 9 wherein said locking iiange includes a tapered conical surface on the forward side thereof to permit the insertion of said central con- 1 tacts through the central bores of said dielectric sleeves. 0
l 0 References Cited UNITED STATES PATENTS 3,088,089 4/1963 Gregoire 339--94 3,184,706 5/1965 Atkins 339-177 FOREIGN PATENTS 900,393 7/ 1962 Great Britain.
MARVIN A. CHAMPION, Primary Examiner. J. H. MCGLYNN, Assistant Examiner.