Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
  • H01R24/58—Contacts spaced along longitudinal axis of engagement
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
  • H01R24/38—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts
  • H01R24/40—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
  • H01R24/52—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency mounted in or to a panel or structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
  • H01R13/62—Means for facilitating engagement or disengagement of coupling parts or for holding them in engagement
  • H01R13/629—Additional means for facilitating engagement or disengagement of coupling parts, e.g. aligning or guiding means, levers, gas pressure electrical locking indicators, manufacturing tolerances
  • H01R13/631—Additional means for facilitating engagement or disengagement of coupling parts, e.g. aligning or guiding means, levers, gas pressure electrical locking indicators, manufacturing tolerances for engagement only

Definitions

• This invention relates to coaxial electrical connectors, and more particularly to connectors for use in high frequency applications where the connector may not be fully engaged properly such as in quick connect/disconnect connectors and modular multiple connector assemblies for electrically connecting two modules together and simultaneously making multiple coaxial connections.
• Coaxial transmission lines and connectors for use therewith include generally cylindrical inner and outer conductors which are axially aligned and separated by a dielectric material.
• the dielectric within a cable is generally a flexible solid or foam which holds the inner conductor in the center of the cable and permits the cable to flex or bend as required.
• the dielectric material within a connector is generally a combination of a solid in one region of the connector to hold the conductors in alignment and air in another region.
• a coaxial transmission line or connector as described above has a characteristic impedance determined by the outer diameter of the inner conductor (referenced by a lower case “d” herein), the inner diameter of the outer conductor (referenced by an upper case “D” herein) and the dielectric constant (referenced by the Greek letter epsilon " ⁇ " herein) of the material in the space between the two conductors which forms the signal pathway.
• the characteristic impedance of a coaxial transmission line is determined by the formula:
• Z is the impedance of the line.
• a connector In order for a connector to minimize signal disruption as the signal passes through the connector, it must also have a characteristic impedance at each point along its length which matches the impedance of the transmission line as set by the formula above. An impedance mismatch causes severe signal disruption, particularly in high frequency applications above one (1) gigaHertz.
• a high frequency coaxial connector will generally include at least some portion wherein the region between the inner and outer conductors is filled with air and another region wherein the space between the inner and outer conductors is filled with an insulating dielectric solid, such as teflon, to hold the inner conductor in coaxial alignment with the outer conductor.
• the dielectric constant of the teflon is different from that of air which may in turn be different from the insulating dielectric material used in the coaxial cable.
• the dielectric constant ⁇ is also generally the same on both sides of the transition point from the male to the female plug.
• the required condition of constant impedance along the length of the engaged connector is achieved by closing the gap between the plugs sufficiently that it can be ignored at the maximum frequency that the connector is designed to operate.
• the outer conductor of the female plug is enlarged at its free end (thereby increasing D). This permits the outer conductor of the male plug to slide into the enlarged outer conductor of the female plug and make a butt joint (and a good mechanical and electrical connection) between the end of the male connector and the inside lip of the outer conductor on the female connector.
• “Blind-mate” connectors are connectors used at the back end of a sliding module, for example, which makes all the necessary connections as the module slides into place. Such connectors are often "remotely located” in the sense that a fastener at the front of the module sets the location of the back of the module having one half of the connector, the other half being positioned on the frame in which the module is placed. Accordingly, the locating mechanism which determines the depth of insertion of one plug into the other is "remotely located” from the plugs themselves. Manufacturing tolerance variations or simple warps in the mounting frame all directly affect the gap between the two plugs.
• the present invention employs a novel design wherein the inner and outer conductors on the male and female plugs do not need to "butt" into each other. Instead, the conductors are designed to form an overlap region between the two plug halves which roughly corresponds to the gap in a prior art connector, the overlap region being intentionally designed so that it may form part of the signal pathway and have an impedance which matches the rest of the connector.
• the connector has a constant impedance along its entire length from the moment its two halves are first electrically engaged, and the size of the "gap" or overlap region may be made as large as desired without affecting the impedance of the connector.
• a connector having a first plug for connection to a mating second plug.
• the first plug as shown in the drawings can be considered the male plug and the second plug can be considered to be the female plug, however, due to the design of the optional shield on the male plug which makes a female-type connection, the terms first and second plugs will be used to avoid confusion.
• Each plug is provided with an inner conductor, an outer conductor and a dielectric spacer therebetween and in each, the inner and outer conductors are of unequal length at their free end such that one projects beyond the other.
• the inner and outer conductors of the first plug are designed to mate with the inner and outer conductors of the second plug.
• the plugs are designed such that the longer inner conductor and the longer outer conductor from the first and second plugs overlap each other as the connector is first electrically connected and only partially engaged. This defines an overlap region between the inner conductor from one plug and the outer conductor from the other.
• the inner and outer conductors are shaped, particularly in their relative diameters d and D, and the dielectric material of the spacers is chosen such that along the axis of the partially engaged connector, particularly within the overlap region, the effective outer diameter of the inner conductor (d) and the effective inner diameter of the outer conductor (D) and the dielectric constant of the medium therebetween ( ⁇ ) satisfy the equation:
• Z is the impedance and is substantially constant along the length of the connector as the plugs are moved from the first electrically connected, partially engaged position to the fully engaged position.
• Fig. 1 is a perspective view of a connector according to the present invention. It should be noted that this view obscures several of the important characteristics of the invention which can be seen only in the longitudinal section views.
• Fig. 2 is a side elevation, mostly in longitudinal section along the line 2-2 of Fig. 1.
• Fig. 3 is a longitudinal section view of the connector showing the first and second plugs partially engaged.
• Figs. 4 and 5 are end views into the open mating ends, i.e. the "free" ends, of the connectors taken along the lines 4-4 and 5-5 marked in Fig 2, respectively.
• Fig. 6 is a longitudinal section view of a single prior art connector
• Fig. 7 is a longitudinal section view of a three connector block using the connector of the present invention showing one of the connectors being not fully engaged.
• Fig. 6 shows a longitudinal section view of a simplified prior art connector. A discussion of this connector and the problems encountered when the connector is not fully seated will be helpful in understanding the present invention.
• the prior art connector seen in Fig. 6 comprises a male plug 10 and a female plug 12.
• the male plug comprises an outer conductor 14 having an inner diameter D 1 , and an inner conductor 16 having an outer diameter di which is coaxially aligned with the outer conductor.
• the female plug 12 also includes an outer conductor 18 and an inner conductor 20 having the same critical diameters D 1 and d 1 in the major portion of its body as in the male plug.
• the space between the inner and outer conductors is filled with a dielectric material 22 having a dielectric constant ⁇ .
• the dielectric material is shown to extend throughout the interior of the plug, however in many connectors, only a portion of each plug is filled with the dielectric material; the remaining portions being open wherein the dielectric material is air.
• the plugs shown in Fig. 6 are shown to be not fully engaged, having a small gap between the plugs.
• the characteristic impedance of the male plug is described by the formula:
• This formula also describes the characteristic impedance of the female half of the connector 12, and accordingly if the plugs were fully seated, the male outer conductor 14 and the female outer conductor 18 would be butted together at faces 24, 26 as would the inner conductors 16 and 20 at faces 28, 30 thereby providing a constant impedance along the entire length of the connector.
• the outer conductor 18 of the female plug has an enlarged inner diameter D 2 .
• the inner conductor 16 of the male plug has a reduced outer diameter d 2 as required to make the connections between the male 10 and female plugs 12.
• the impedance of the connector is described by the formula:
• ⁇ air the dielectric constant of air
• ⁇ air the dielectric constant of most solid dielectrics which are commonly in use thereby increasing the factor ( ⁇ )-1 ⁇ 2.
• the increased D and decreased d in the gap both act to increase the ratio D 2 /d 2 thereby increasing the factor log (D 2 /d 2 ) as compared to log (D 1 /d 1 ).
• Preferred Embodiment of the Connector Fig. 1 shows a perspective view of the preferred embodiment of the connector. Many of the important features of the connector, however, are internal and are obscured by the exterior view seen in Fig. 1. Nonetheless, this figure is helpful for general orientation regarding the connector.
• the connector is comprised of a first plug 32, and a second plug 34.
• the two plugs each have various enlarged rings 36, 38 around their circumference which are principally used to attach the individual plugs 32, 34 to a connector housing (not shown, but indicated generally in Fig. 7) for use in multiple connector modular assemblies.
• the first plug includes a shield 40 with slots 42 which permits the shield 40 to be compressed slightly during manufacture thereby making firm electrical contact with the outer conductor 44 on the second plug 34 when the plugs are engaged.
• first plug 32 Also visible on the first plug 32 is a portion of the free end of the inner conductor 46 of the first plug, the free end being the end which connects to the other plug.
• the visible end of the inner conductor 48 is the end for connection to the coaxial transmission line, not the free end.
• This end can have any standard configuration known to the art for making a connection to a coaxial transmission line.
• the end may be straight or right-angled and generally involves a soldered joint which makes a good low loss, substantially constant impedance connection between the coaxial transmission line and the second plug.
• Fig. 2 is a side elevational view of the connector along the line 2-2 seen in Fig. 1. This view is taken mostly in section in order to illustrate the important features of the invention.
• first plug 32 can be divided into four regions marked with reference numerals 50-56 which correspond to four regions on the second plug 34 marked with reference numerals 58-64.
• first plug 32 comprises four separate mechanical pieces, namely, the inner conductor 46, the outer conductor 66, the shield 40 and a dielectric spacer 68.
• the second plug 34 comprises three pieces including the inner conductor 48, the outer conductor 44 and the dielectric spacer 70.
• Regions 50 and 64 in the first and second plugs respectively are the coaxial cable connection regions, i.e., the regions in which the signal first passes from the coaxial cable into or out of the connector. As indicated above, these regions are designed with standard techniques to mate with the specified coaxial cable and provide an exact impedance match such that the signal is transferred effectively to the first and second plugs respectively. Generally, to make this connection, the outer conductor and the dielectric material of the coaxial cable are stripped back from the inner conductor of the coaxial cable. The inner conductor of the coaxial cable is inserted into the inner conductor 46 of the first plug 32 in the axial opening marked with reference numeral 72. A corresponding axial opening 73 is provided in inner conductor 48.
• the signal is passing in the pathway defined between the inner and outer conductors of the coaxial cable.
• the signal is in the pathway defined between the shield 40 and the inner conductor 72 in the first plug 32, and between the outer conductor 44 and the inner conductor 48 in the second plug 34. The space between these regions is filled with air.
• the leftmost portion of shield 40 in region 50 acts as the outer conductor and defines the critical diameter D in that region.
• Reference to Fig. 3 shows that the critical diameter ratio D3/d3 defines the impedance of the connector in region 50 according to the formula:
• the diameters D and d in region 64 may be the same as in region 50, and must have the same ratio D 3 /d 3 because the dielectric material is the same (air) in both regions. However, in the preferred embodiment, they are slightly different than D 3 and d 3 , for simplified assembly of the final connector.
• Regions 52 and 62 are the dielectric spacer regions wherein the space between the inner conductor and outer conductor on each plug is filled with a dielectric spacer.
• the dielectric spacer is preferably made of teflon, however, it may be of any of the many suitable dielectric materials which are well-known for use in high frequency connectors. The dielectric spacer holds the connector together, keeping the inner conductors axially aligned in the center of the outer conductors in each plug.
• the diameters D 4 ,d 4 in region 52 must be adjusted to maintain the impedance within region 52 to match the impedance within region 50 and within the coaxial cable itself.
• the diameters D 4 ,d 4 are chosen such that:
• This offsetting of the transitions of the inner and outer conductors is an empirically derived adjustment required because the impedance formula given above is completely accurate for the actual measured diameters D and d only in regions where the electric field lines are substantially radially aligned in the connector. This occurs only where the inner and outer diameters (d and D) are not changing rapidly. The formula does not give completely accurate results in regions where the diameters d and D are rapidly changing which causes the electric field lines to diverge from their radial alignment.
• the "effective" diameters d,D when substituted into the formula above produce the actual impedance in the vicinity of a rapid change in the actual diameters D,d.
• the effective diameters are quite close to the actual diameters even at the points of rapid transition of actual diameters. In regions where the actual diameter is unchanging, the effective diameter equals the actual measured diameter. It is the actual diameter which is generally used to calculate the impedance of the connector. However, it is the effective diameter which must be controlled even though most practitioners of the art of designing such connectors fail to distinguish the two.
• the regions marked with reference numerals 54 and 60 may be referred to herein as the "free space" regions.
• the relative diameters D 5 ,d 5 as indicated in Fig. 3 are selected once again to match the characteristic impedance of the remaining portions of the connector *
• the dielectric material between the inner conductor 46 and the outer conductor 66 is air and accordingly the ratio D 5 /d 5 must be the same as the ratio D 3 /d 3 .
• the outer conductor 66 within region 54 has slots 74 which permit the free end of outer conductor 66 to be slightly enlarged thereby making electrical contact at its free end with the interior of the outer conductor of the second plug 44.
• the inner conductor of the first plug 46 projects beyond the outer conductor 66.
• the projecting end of the inner conductor 46 in region 56 is enlarged in region 56, having an outer diameter d 6 which is greater than its diameter d 5 in region 54.
• the inner conductor 66 stops short of region 56.
• the outer shield conductor 40 does not form part of the signal passageway when the connector is connected. Accordingly, the projecting portion of the inner conductor 46 in region 56, having a diameter d 6 , has as its corresponding outer conductor, the outer conductor 44 on the second plug in region 58 which has an inner diameter D 6 as marked in Fig. 2.
• the operational similarity of the second plug to the first plug can be seen.
• the signal would enter the connector from the coaxial cable as previously described, entering regions 64, passing into region 62 and then into region 60, each of the regions described, 60-64 having the same characteristic impedance as the coaxial cable and as the corresponding regions 50-54 in the first plug.
• the inner and outer conductors 48, 44 in the second plug are of unequal lengths.
• the longer conductor is the outer conductor 44 which projects beyond the inner conductor 48 in region 58.
• the projecting member, which for the second plug is the outer conductor 44, has a change of its critical diameter as it goes from the free-space region 60 to the region 58.
• the critical diameter is its inner diameter D whi ch changes to the reduced diameter D 6 i n reg ion 58 as compared to the corresponding larger inner diameter D in region 60.
• regions 54, 56, 58 and 60 all have substantially the same length and, accordingly, as the connectors are engaged, the outer conductor 44 on the second plug in region 58 slides into the interior of the shield 40 on the first plug until the two outer conductors 66 and 44 contact each other. At approximately this point, the inner conductors 46 and 48 also make contact and the connectors form the electrical connection.
• the connector has an overlap region defined by the overlap between regions 56 and 58.
• the enlarged projecting portion of the inner conductor 46 and the reduced projecting portion of the outer conductor 44 form a transitional signal pathway between the two plugs having a characteristic impedance defined by the ratio D 6 /d 6 .
• These diameters are chosen to provide a matching impedance to the impedance elsewhere in the connector, and it is this match which is essential to producing a constant impedance along the length of the connector, even when the connector is only partially engaged.
• the overlap region between regions 56 and 58 diminishes in size as the outer conductor 44 slides over the outer conductor 66 and ceases to function as part of the signal pathway.
• the projecting end of inner conductor 46 slides into the inner conductor 48 and also ceases to function as part of the signal pathway.
• regions 54, 56, 58 and 60 are all approximately 0.10 inches (2.5 mm) in length which is more than sufficient for compensating for the variations in the depth of engagement of the two plugs which might occur in any of the applications previously discussed.
• the preferred length of regions 54, 56, 58 and 60 all provide a compensation which is about 10 times greater than prior art compensating designs.
• the overlap region is designed to form part of the signal pathway with a matching impedance to the rest of the connector, it is not necessary that the connector be fully engaged. It is perfectly suitable for the connector to be used in applications where it might always be partially engaged *
• the free end of inner conductor 48 may be provided with slots 75. The end may then be lightly compressed to make electrical contact with the free end of inner conductor 46. All of the slots, seen best in Figs. 4 and 5, and the compression or expansion of the slotted members are optional and may be adjusted as desired to swit the application.
• the various components of the connectors are manufactured, the conductive components usually being p lated wi th a highly conduct ive non-oxi dizi ng mater ial such as gold, and then assembled.
• the dielectric spacers 68, 70 may be held in position by adhesive or by lightly crimping or indenting the exterior of the outer conductors.
• FIG. 7 shows a plurality of the connectors of the present invention identified with reference numerals 76, 78, 80.
• the first plugs of each connector are mounted in a connector block 82 and the second plugs are mounted in connector block 84.
• connector block 82 would be mounted to the back of an electrical module and connector block 84 would be mounted to the rear of a frame into which the electrical module would slide such that the connectors would mate when the module was positioned within the frame.
• connectors 76 and 80 are fully seated whereas connector 78 is shown to be only partially seated due to some misalignment or manufacturing variation.
• the region marked with reference numeral 86 would, in a prior art connector, be a gap causing an impedance mismatch through connector 78, however in the present connector this is the overlap region which is designed to form part of the signal pathway and which includes a characteristic impedance which matches the impedance elsewhere in the connectors and transmission line.

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• Coupling Device And Connection With Printed Circuit (AREA)
• Details Of Connecting Devices For Male And Female Coupling (AREA)
• Communication Cables (AREA)
• Non-Reversible Transmitting Devices (AREA)

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• 1988
  • 1988-10-07 AT AT88909448T patent/ATE141028T1/de not_active IP Right Cessation
  • 1988-10-07 JP JP63508703A patent/JPH02501690A/ja active Granted
  • 1988-10-07 EP EP88909448A patent/EP0339067B1/en not_active Expired - Lifetime
  • 1988-10-07 DE DE3855456T patent/DE3855456D1/de not_active Expired - Lifetime
  • 1988-10-07 WO PCT/US1988/003483 patent/WO1989003600A1/en active IP Right Grant
• 1989
  • 1989-06-13 KR KR1019890701069A patent/KR890702295A/ko not_active Withdrawn

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