US3579282A

US3579282A - Transmission line connector with means including cam surfaces for altering connector element dimensions to compensate for junction gaps, and method therefor

Info

Publication number: US3579282A
Application number: US788812A
Authority: US
Inventors: William Dean Couper
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1969-01-03
Filing date: 1969-01-03
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: JPS4934434B1; NO129173B; NL6919133A; AT321998B; BE743878A; CH527499A; FR2030122A1; ES374964A1; SE351528B; DE1963078A1; FR2030122B1; GB1254619A; DK128258B; NL149650B

Abstract

A microwave coaxial connector structure is disclosed which features mating contact elements shaped to provide automatic compensation for physical discontinuities caused by improper mating. The contact elements include a male portion having a diameter which varies along a segment thereof and a female portion which engages such segment and is displaced radially, more or less depending upon the degree of seating, or relative axial position, of the segment within the female portion. If contact elements are not fully seated a high impedance mismatch is caused by a radial gap therebetween. The invention structure operates to create a counterbalancing low impedance due to the radial expansion of the mating element. The balancing low impedance is made to be physically close to the high impedance relative to signal wavelength. The invention is also taught in a reverse structure for outer conductive mating parts of a connector.

Description

United States Patent [72] inventor William Dean Couper Palmyra, Pa.

[21] Appl. No. 788,812

[22] Filed Jan. 3, 1969 [45] Patented May 18, I971 [73] Assignee AMP Incorporated Harrisburg, Pa.

[54] TRANSMISSION LINE CONNECTOR WITH MEANS INCLUDING CAM SURFACES FOR ALTERING CONNECTOR ELEMENT DIMENSIONS TO COMPENSATE FOR JUNCTION GAPS, AND METHOD THEREFOR 6 Claims, 9 Drawing Figs.

[52] US. Cl 333/97,

[51] Int. Cl H0lp 1/00,

H0lp 5/08 [50] Field of Search 333/97, 34, 33, 35; 339/177, 258, 262(Cursory); 174/75.2, 21.3,71 (C), 88.2

[56] References Cited UNITED STATES PATENTS 2,152,504 3/1939 Scott et al 174/882 2,548,457 4/1951 Wilson 174/882 3,245,027 4/1966 Ziegler, Jr. 333/97X FOREIGN PATENTS 901,203 7/1945 France 333/97 OTHER REFERENCES MacKenzie, GENERAL RADIO EXPERIMENTER, July, 1966,pps. l4 l5 MacKenzie et al., Some Fundamental Design Principles for the Development of Precision Coaxial Standards & Components," MTT- 1401, l-1966 pps. 29 39 Primary Examiner-Eli Lieberman Assistant Examiner-Wm. H. Punter Attorneys-Curtis, Morris and Safford, Marshall M.

Holcombe, William Hintze, William J. Keating, Frederick W. Raring, John R. Hopkins, Adrian J. La Rue and Jay L. Seitchik ABSTRACT: A microwave coaxial connector structure is disclosed which features mating contact elements shaped to provide automatic compensation for physical discontinuities caused by improper mating. The contact elements include a male portion having a diameter which varies along a segment thereof and a female portion which engages such segment and is displaced radially, more or less depending upon the degree of seating, or relative axial position, of the segment within the female portion. If contact elements are not fully seated a high impedance mismatch is caused by a radial gap therebetween. The invention structure operates to create a counterbalancing low impedance due to the radial expansion of the mating element. The balancing low impedance is made to be physically close to the high impedance relative to signal wavelength. The invention is also taught in a reverse structure for outer conductive mating parts of a connector.

Patented May 18, 1971 5 Shoets Sheot 1 PR/OI? ART INVENTOR. WILLIAM DEA COUPEK Patented May 18, 1971 3,579,282

3 Sheets-Sheat 2 INVENTOR. MLLBAM DEAN COUP EQ Patented May 18, 1971 3,579,282

3 Shoots-Shoat 8 VSWR HT SEGMENT STRAIG 4 4 I TAPERED SEGMENT I 02 s=o.ooo .002

STRAIGHT SEGMENT/ TATERED SIEGMENT 8 INVENTOR. Ghl.

(MIL-LIAM DEAN COUPEFL TRANSMISSION LINE CONNECTOR WITH MEANS INCLUDING CAM SURFACES FOR ALTERING CONNECTOR ELEMENT DIMENSIONS TO COMPENSATE FOR JUNCTION GAPS, AND METHOD THEREFOR BACKGROUND OF THE INVENTION In high frequency coaxial connector devices, inner and outer conductive elements are typically connected to inner or outer conductors of a cable of some means afiording a permanent or semiperrnanent type of termination. Portions of these elements are dimensioned and shaped to provide a mateable contact engagement which may be made and broken to interconnect two cables. In microwave applications considerable care is used to maintain precise dimensions with respect to diameters of inner and outer conductive cable parts and the surfaces thereof and with respect to the positioning of dielectric material within the cable. By the same token considerable precision is called for in connector devices used for such cable. The reason for the requirement of precision is that the cable and associated connector devices are used with signals which have very short wavelengths and even small physical discontinuities have a substantial and adverse effect. In making a connector device which is intermateable the inner and outer conductive elements usually have spring members to facilitate mateability. Since the mating halves on the rear ends are permanently or semipermanently joined to the cable conductive portions, these elements are relatively fixed in an axial sense. Theoretically, a connector device should be made so that when the two halves are mated there is an exact joining of the ends of the inner and outer conductive elements with no radial gap. Practically speaking, this is not possible on even a limited production basis, since all manufactured parts have tolerances and variations are introduced in assembly. An under tolerance produces radial gaps in either the inner or outer conductive elements of the connector. An over tolerance may produce an axial loading of one or the other of the elements of the connector to cause an unwanted displacement thereof with a radial gap created in the other elements. For this reason many of the prior art devices have been dimensioned so as to provide a mating in only one or the other of the inner and outer conductive elements of the connector, usually in the outer conductor, with an expected gap left in the inner contact element. In certain instances connectors have been modified to attempt to compensate for such gaps by a fixed structure. On the whole, a fixed structure is not satisfactory because there is constant variations from part to part. In many instances the fixed structure does more harm than good and results in an overall poorer performance for given numbers of connectors.

SUMMARY OF THE INVENTION The present invention relates to a method and means for compensating high frequency coaxial devices such as connectors and the like.

It is an object of the present invention to provide a simple and inexpensive way to automatically compensate for radial gaps in the inner and/or outer conductive elements of coaxial connectors and the like. It is another object to provide a method and means for compensation of coaxial connector devices which automatically adjusts itself in the presence of production and assembly tolerances causing variations in part dimensions or in part placement. It is yet another object to provide an improved coaxial connector device for high frequency applications.

The foregoing objects are attained in the present invention by providing, in the mating parts of connector devices, surfaces shaped to be displaced in a radial sense inwardly and outwardly in proportion to an adjacent radial gap between the pieces caused by variations in manufacturing dimensions or assembly techniques. With respect to center conductor structures, a pin element is provided with a segment which varies along its length from a predetermined minimum diameter to a predetermined maximum diameter. A mating ferrule portion includes an interiorly directed rib which rides upon such segment to enlarge the female portion outer diameter to an extent related to the relative axial position of the contact elements and the radial gap created by the lack of complete engagement. The high impedance mismatch created by the radial gap is compensated for by an adjacent low impedance caused by a diameter increase. In another embodiment a similar structure is provided in the outer conductive portions of a connector to compensate for radial gaps defined between such portions.

In the drawings:

FIG. 1 is a perspective view of a coaxial connector joining two coaxial cables together for transmission of high frequency signal energy;

FIG. 2 is a view of a structure similar to that of FIG. I, but with a portion of the connector cut away to depict the interior thereof;

FIG. 3 is a schematic representation of the cross section of a connector in accordance with the prior an included to reveal one aspect of the problem solved by the present invention;

FIG. 4 is a longitudinal view, partially sectioned and considerably enlarged, showing the center contact structure of the invention in accordance with a preferred embodiment;

FIG. 5 is a view of the structure shown in FIG. 4 but pulled apart to depict the action of the invention in providing compensation;

FIG. 6 is a perspective view of the structure shown in FIGS. 4 and 5 in a disengaged position;

FIG. 7 is a longitudinal and sectional view depicting the invention as adapted to the outer conductive portions of a connector;

FIG. 8 is a view of the structure shown in fig. 7 slightly I pulled apart, depicting the invention structure in operation; and

FIG. 9 is a plot of VSWR versus frequency in Ghz. showing the results of a controlled experiment utilizing a straight pin contact structure of the prior art and a version of the contact structure of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A connector cable assembly 10 is shown in FIG. I joining two coaxial cables to provide a path for the transmission of signal energy. Each cable 12 is, in the illustrative embodiment, identical and includes a center conductor l4 surrounded by a dielectric material 16 and an outer conductor 18. In microwave use, cable of this general construction is made with precision with close tolerances carried as to the diameters of the conductive elements and as to the characteristics of the dielectric material employed. Performance of the cable in microwave use depends in large measure upon how well the cable is made to avoid physical discontinuities and lack of concentricity. These facts are typical causes of signal loss and reflections and a general deterioration of cable performance as a transmission line.

Connectors for cable of the type shown in FIG. 1 are made of two halves, plug and jack, which are interrnateable and which provide some mechanical means for holding the halves together in use. Typically, each connector half is permanently or semipermanently joined to the cable with inner and outer conductive elements of each connector half joined to inner and outer conductive elements of the cable, respectively. Appropriate joints may be made by soldering the metal elements of the connectors halves to the metal elements of the cable. Other ways are known for providing a clamping or wedging structure for terminating parts of the cable to the connector halves. In the showing of FIG. 2, connector 20 includes a half 22 and a half 24. The half 24 includes a connector body in the form of a shell 26 threaded externally as at 41 on its forward end to mate with a ring 34 internally threaded and fitted onto the body of half 22. The body of half 22 includes a shell which can be seen in part associated with numeral 32 in FIG. 2. The connector halves are hollow as mentioned and may include a dielectric sleeve, such as 33 shown in FIG. 2, which extends along a portion of the interior and surrounds a center contact structure comprised of

elements

36 and 44 as shown in FIG. 2. This contact structure is comprised of contact pin element 36 and contact receptacle element 44, the latter having a spring action so as to receive the pin element in mating engagement. The rear portions of each of the

shells

26 and 32 are terminated to the cable outer conductors 18, by some suitable means such as a wedge ring. The contact elements are in a similar manner terminated to the center conductor elements 14 of the cable as by being threaded therein or soldered thereto. The termination of the inner and outer conductive structures of the connector to the cable is, as mentioned, permanent or semipermanent, which means that the ends of such elements are fixed relative to the ends of the cable. As a practical matter this means that relative to actual production and assembly of connectors onto cable, even very slight variations in the axial dimensions of the inner and outer conductive parts of the connector become significant.

FIG. 3 represents a section through a connector having cer tain features in accordance with the prior art. The outer conductive elements of the connector are depicted as OC and the center contact elements are depicted as CC. As can be discerned, the outer conductive elements are butted together as at BJ and the inner conductive elements are intennated with a slight radial gap or space S left therebetween. This is one way connectors are made. Dimensions of the connector are set so as to provide a butt joint on the outer conductor element with some gap left between the center conductive elements. If this were not done and if tolerance permitted a butt joint to occur in the center conductive element before closure of the outer conductive elements, the connector halves could not be fitted together without jamming and forcing the center conductive elements. What happens when this occurs is that the elements usually bow to one side, as indicated by the dotted line, to destroy concentricity and effectively ruin high frequency perfonnance as a transmission line. Another possibility is that the binding together of the elements will tend to jam the center conductors and cause a bow elsewhere or center conductor slippage within the cable dielectric, if the coaxial cable segments are relatively short. One known prior art connector utilized for moderately high frequency application is known as a Type-N connector. The gap S is purposely designed to prevent the foregoing problem. An interior ring in the outer conductor OC, shown as C, is provided to compensate for the gap S, caused by leaving some clearance between the center conductor pin and receptacle elements. The compensator C efi'ectively changes the diameter D as to CC to compensate for the change in diameter d in CC caused by gap S. One of the problems with the prior art connectors utilizing this type of compensation is that the gap S varies from connector to connector. Since compensator C is machined into the structure, it cannot change and frequently results in an overcompensation or an under-compensation, which may be worse than having no compensation at all. Put another way, connectors of the prior art with structures for compensating for diameter changes included to assure mateability are fixed structures and cannot accommodate variations in placement of center conductor elements, which variations are necessary for mateability.

In accordance with the invention concept, as shown in FIG. 2, and in greater detail in FIGS. 4-6, the

center contact elements

36 and 44 are made mateable, as in the prior art; the element 36 serving as a pin member and the element 44 serving as a spring receptacle member. These elements are dimensioned as in the prior art to assure mateability of a connector structure by avoiding axial butting of the elements tending to cock the elements to one side or to load the center conductors of cable to which they are attached. FIG. 4 shows the center contact elements mated together in an approximation of maximum expected displacement of

such elements

36 and 44, relative of the axial or length direction thereof of the elements. FIG. 5 shows the elements in an approximation of nominal displacement, it being apparent from FIG. 5 that the elements could be backed away more than is shown to increase the spacing S to a quantity slightly greater than is shown. As can be seen in FIGS. 4, 5 and 6, the pin contact element 36 includes a forward segment comprised of

portions

38, 40 and 42. The portion 38 tapers inwardly toward the body of the contact element to define a cam surface and the portion 42 tapers inwardly away from the body of such element. The portion 38 is preferably of a length slightly greater than the maximum displacement of

contact elements

36 and 44, including all design tolerances, both manufacturing and assembly. The portion 40 is of substantially constant diameter. Contact element 44, which is a receptacle, includes an interior bore 46 adapted to receive the forward segment of pin 36 inserted therewithin. The bore 46 has a diameter to receive portion 40 without being expanded radially. The forward end of the receptacle contact element 44 is made resilient by thin axial slots 48, fonned therein to define spring fingers 50. Slots 48 are minimized in width to minimize changes in the effective outer diameter of the center contact structure. It is worth mentioning that slots which run axially in an outer or inner conductor have much less effect as sources of reflection or causes of impedance mismatch than do slots of the same effective width and depth, which exist in a radial sense in conductors. The interior end portions of spring fingers springs 50 include interior projections or lips shown as 52 in FIGS. 4-6. These lips are dimensioned so as to provide an interior radial surface of engagement providing a camming action when engaged with the cam surfaces on portion 38 of the pin 36. The bore 46 and the lips 52 are dimensioned to receive the forward segment of pin 36 in the manner shown in FIG. 4 effectively expanding the diameter of receptacle 44 very little when gap S is very small. When 5 becomes larger due to displacement of

elements

36 and 44, the cam surface of portion 38 engages lips 52 to cam the spring fingers 50 outwardly increasing the effective outer diameter of receptacle 44. In general, a decrease in the diameter of the center contact elements as caused by the gap or space S causes effective increase in impedance in coaxial planes including S and an increase in the effective diameter of the center contact elements causes a corresponding decrease in the impedance in the planes containing such diameter increase. By an appropriate shaping of the surfaces heretofore described, the diameter d may be made of vary as a function of gap S and thus provide a compensation for S. It is worth noting that the effective increase in diameter of the end of receptacle 44 is adjacent to gap S. As long as these differences in diameter are close together relative to the wavelength of the highest frequency employed in use, an effective compensation will be obtained and a reduced mismatch caused by S will result.

FIG. 9 shows a plot of VSWR vs. frequency in Ghz. for center contact elements having a straight segment as is shown in FIG. 3 and a tapered segment like that of FIGS. 4-6. The solid line plots represent the straight pin segments of the prior art. Plotted in a dotted line is VSWR over a frequency range for the tapered segment made in accordance with the invention. The plot shown in FIG. 9 is based upon a controlled experiment with contact elements fitted within a transmission line. The uppermost lines (solid and dotted) represent the segments for S equal to 0.025 10.002 of an inch, respectively. The lower lines represent the straight and tapered segments when S is equal to very near zero. As can be discerned, the provision of the tapered segment in accordance with the invention represents a very substantial improvement in performance in terms of VSWR.

In an actual embodiment used for the foregoing experiment the portion 38 was 0. I00 of an inch in length, tapering from a diameter ofO. l 74 of an inch to a diameter of 0. l 33 of an inch. The contact element was 0.244 of an inch in diameter. The mating element included a lip 0.135 of an inch in inner diameter from a bore 0.180 of an inch in inner diameter.

Turning now to FIGS. 7 and 8, a connector 60 is shown with the invention concept rendered in the outer conductive structure of the connector. Element 62 represents one connector half threaded on the outside for mating with threading internal to a nut 72 slidably mounted on a mating connector half 70. The interior of element 60 is beveled as at 64 to facilitate insertion of a spring portion 73 of the other connector half 70. At the interior end of 64 a reduced surface 66 which defines a cam surface is provided to receive and cam the end lips 74 of connector half 70 inwardly proportional to the axial spacing between 62 and 70. FIG. 8 shows the connector elements pulled slightly apart. FIGS. 7 and 8 show the

center contact elements

68 and 76 of the two halves bottomed or closed together. The embodiment of FIG. 7 is intended for use where a positive fit of the center contact elements is desired. This may occur with certain types of cable or with certain lengths of cable.

As in the previous example, the invention structure is intended to compensate for the spacing S by producing proportional changes in D, thereby accommodating different production and assembly tolerances. As can be seen when gap, S is increased due to spacing apart of 62 and 70 to create a high impedance segment, the interior of spring portion 73 is cammed in to provide a compensating segment of low impedance just adjacent the location of S. By controlling the dimensions of cam surface 66 and 74, the high impedance section can be made to balance out the low impedance section.

It will be seen that in the embodiment of the invention represented in FIGS. 4-6, the cam surface or portion 38 extends generally outwardly from the longitudinal center of the connector with the lips 52 extending inwardly so as to ride on the said cam surface. Conversely, in the embodiment shown in FIGS. 7 and 8, the cam surface 66 is directed generally inwardly toward the longitudinal center of the connector and the lips 74 are directed generally outwardly to engage cam surface 66.

The foregoing embodiments have been disclosed relative to coaxial cable connectors. The invention contemplates uses with noncoaxial high frequency connector devices. Since the drawings are in plane it is believed that the concept as applied to flat cable or ribbon cable connectors should be readily apparent. As long as system requirements specify that impedance needs to be defined in terms of the geometry of the conductors, whatever their shape, the concept of automatic compensation at the junction of mating parts is contemplated as of possible advantageous application.

The invention also contemplates that contact element segments may be shaped to produce nonlinear effects as by curving the tapered portion 38 in a suitable manner. In certain applications it may be desirable to achieve a given minimum mismatch at a junction. Within the limits of tolerancing, the invention may be so used and is contemplated for such use by appropriately adjusting the dimensions of the mating contact elements.

Having now disclosed my concept in tenns intended to enable its practice in preferred modes, I define it through the appended claims:

lclaim:

1. In a connection of high frequency transmission lines defined by inner and outer conductors spaced apart to an extent to define a given characteristic impedance, a connector device having inner and outer conductive elements spaced apart to define a characteristic impedance substantially similar to said given characteristic impedance, the said elements including surfaces shaped to provide intermating to form a junction with said elements being mechanically and electrically joined to corresponding inner and outer conductors of said line, the said elements being dimensioned so that either the inner or outer portions thereof are substantially closed together with the other portions being dimensioned to not quite close together creating a radial gap to accommodate production and assembly tolerances and prevent displacement of said elements and/or the conductors of said line, the said other portions of said elements including mating surfaces shaped to provide a radial expansion or contraction altering the radial spacing between the'inner and outer elements in proportion to the length of said gap to create balancing impedance effects proximate one another at said junction to compensate for said gap.

2. In a connector for use with high frequency transmission line of the type comprised of conductors spaced apart to define a given characteristic impedance, said connector including corresponding conductive elements spaced apart to define essentially said given characteristic impedance, said conductive elements including at least a pair of mating portions which have surfaces shaped to provide intermating to form a junction, with means on the ends thereof operable to effect a transverse displacement of the surfaces of said portions altering the spacing between said elements in proportion to the extent of axial mating of the portions and any corresponding alternation in transverse dimension of the surface of the portions at said junction whereby to provide an automatic compensation for gaps created at said junction.

3. In a connector for use with high frequency transmission line of the type comprised of conductors spaced apart to define a given characteristic impedance, said connector including corresponding conductive elements spaced apart to define essentially said given characteristic impedance, said conductive elements including at least a pair of mating portions which have surfaces shaped to provide intermating to form a junction, with means on the ends thereof operable to effect a transverse displacement of the surface of said portions altering the spacing between said elements in proportion to the extent of axial mating of the portions and any corresponding alteration in transverse dimension of the surfaces of the portions at said junction whereby to provide an automatic compensation for gaps created at said junction, said means comprising a cam surface on one mating portion and a lip on a second mating portion, the second mating portion having spring means biasing said lip to engage said cam surface so as to directly displace the surface of said second mating portion transversely in proportion to the position of said lip on said cam surface relative to the length axis of the mating portions.

4. In a connector for use with high frequency transmission line of the type comprised of conductors spaced apart to define a given characteristic impedance, said connector including corresponding conductive elements spaced apart to define essentially said given characteristic impedance, said conductive elements including at least a pair of mating portions which have surfaces shaped to provide intermating to form a junction, with means one the ends thereof operable to effect a transverse displacement of the surface of said portions altering the spacing between said elements inproportion to the extent of axial mating of the portions and any correspond ing alteration in transverse dimension of the surfaces of the portions at said junction whereby to provide an automatic compensation for gaps created at said junction, said means comprising a cam surface on one of said mating portions extended generally outwardly from the longitudinal center of said connector with another of said mating portions including a lip extending inwardly in a position to ride on said cam surface, the said other portion having spring means to bias said lip against said cam surface so as to cause said other portion to respond dimensionally to the position of said lip on said cam surface.

5. In a connector for use with high frequency transmission line of the type comprised of conductors spaced apart to define a given characteristic impedance, said connector including corresponding conductive elements spaced apart to define essentially said given characteristic impedance, said conductive elements including at least a pair of mating portions which have surfaces shaped to provide intermating to form a junction, with means on the ends thereof operable to effect a transverse displacement of the surface of said portions altering the spacing between said elements in proportion to the extent of axial mating of the portions and any corresponding alteration in transverse dimension of the surfaces of the portions at said junction whereby to provide an automatic compensation for gaps created at said junction, said means comprising a cam surface on one of said mating portions directed generally inwardly toward the longitudinal center of said connector and another of said mating portions includes a lip directed generally outwardly, with said other portion including spring means to bias said lip into engagement with said cam surface and alter the transverse dimensional configuration of said other portion in proportion to the relative axial position of the mating portions.

6. A method for automatically compensating for physical changes in a connector that joins high frequency transmission line cables of the type comprised of conductors spaced apart to define a given characteristic impedance, wherein said connector includes corresponding conductive portions spaced apart to define essentially said given characteristic impedance, said method comprising the steps of providing mating connector halves for inner and outer cable conductors, dimensioning said connector halves at a region of junction thereof so that one portion of each connector half closes axially to define a substantially gap-free surface with the other portions of the connector halves dimensioned so as to not quite close, thereby creating a radial gap to accommodate production and assembly tolerances, providing on at least one half of said other portions at the region of junction a means responsive to the axial position of the mated connector halves to expand or contract radially and radially displace the surface of one of said portions adjacent to said radial gap to compensate for variations in the length of said gap by producing a variation in impedance opposite and substantially proportional to impedance variations caused by said gap.

PO-lOSO Patent No. 3,579,282

Dated May 18, 1971 'I t WILLIAM DEAN COUPER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r. Column 6, Claim 2, line 16, "alternation" should I be alteration Same column, Claim L line 1+6, "one" should be Same column, Claim 5, line 69, "surface" should be surfaces Column 8, Claim 6, line 11, before "portions" should be inserted other Signed and sealed this 21st day of September 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer AMP 2664 ROBERT GOTTSCHALK Acting Commissioner of Patents

Claims

1. In a connection of high frequency transmission lines defined by inner and outer conductors spaced apart to an extent to define a given characteristic impedance, a connector device having inner and outer conductive elements spaced apart to define a characteristic impedance substantially similar to said given characteristic impedance, the said elements including surfaces shaped to provide intermating to form a junction with said elements being mechanically and electrically joined to corresponding inner and outer conductors of said line, the said elements being dimensioned so that either the inner or outer portions thereof are substantially closed together with the other portions being dimensioned to not quite close together creating a radial gap to accommodate production and assembly tolerances and prevent displacement of said elements and/or the conductors of said line, the said other portions of said elements including mating surfaces shaped to provide a radial expansion or contraction altering the radial spacing between the inner and outer elements in proportion to the length of said gap to create balancing impedance effects proximate one another at said junction to compensate for said gap.

4. In a connector for use with high frequency transmission line of the type comprised of conductors spaced apart to define a given characteristic impedance, said connector including corresponding conductive elements spaced apart to define essentially said given characteristic impedance, said conductive elements including at least a pair of mating portions which have surfaces shaped to provide intermating to form a junction, with means one the ends thereof operable to effect a transverse displacement of the surface of said portions altering the spacing between said elements in proportion to the extent of axial mating of the portions and any corresponding alteration in transverse dimension of the surfaces of the portions at said junction whereby to provide an automatic compensation for gaps created at said junction, said means comprising a cam surface on one of said mating portions extended generally outwardly from the longitudinal center of said connector with another of said mating portions including a lip extending inwardly in a position to ride on said cam surface, the said other portion having spring means to bias said lip against said cam surface so as to cause said other portion to respond dimensionally to the position of said lip on said cam surface.