Joint assembly for coaxial cable

Abstract

A coaxial joint assembly 10 has a characteristic impedance Z0'and includes an inner conductive structure 32 having opposing first and second ends 34.1 and 34.2, the first and second ends 34.1 and 34.2 being connectable to an inner conductor of a coaxial cable and an inner conductor 18 of a port, respectively. The cable has a characteristic impedance Z0 and the inner conductor has a diameter d1. The structure 32 has an outer diameter d1'greater than d1. The electrically conductive tubular member 36 has an inner diameter D1 ', a first end 38.1, a second end 38.2, a slot 40, and an inner surface area A' inner. The member 36 is connectable at its end 38.1 to the outer conductor of the cable and at its end 38.2 to the outer conductor of the port. The assembly 10 comprises a dielectric arrangement 42 having a dielectric constant [epsilon] eff '. At least one of a) epsilon eff'and b) A'inner is configured such that the difference between Z0 and Z0 'is less than 3% and the change in D1 and D1' is less than 5%.

Description

Technical Field

[0001] The present invention relates to a splice assembly for forming a fixed joint or permanent splice between a coaxial cable and a terminal device having a port or connection point with a coaxial conductor arrangement. Background Art

[0002] The terminal device may be a second coaxial cable, an RF connector, an RF electronic circuit, an antenna, a housing containing RF electronic equipment, etc. Antennas and other radio frequency (RF) appliances are typically provided with a first section of coaxial cable connected to the antenna at one end and to a connector at the other end. In use, the connector may be connected to a cooperating connector at one end of the second section of coaxial cable to form a connection between the first cable and the second cable.

[0003] The disadvantages of cooperating connectors are that they are bulky, susceptible to failure over time for many applications where sealing is required, and impedance mismatches can occur due to the deterioration of this connection, which is most problematic at higher frequencies (e.g. above 2Ghz).

[0004] As is known to all, a coaxial cable comprises an inner conductor having an outer diameter (d1), an outer conductor having an inner diameter (D1), and a dielectric material having an effective dielectric constant (ε) formed between the inner and outer conductors. eff ) body. It is also known that the characteristic impedance (Z0) of a coaxial cable is proportional to the ratio D1 / d1. It is well known that Z0 is proportional to ε eff In addition, Z0 is inversely proportional to the distributed capacitance per meter (C / m) between the inner conductor and the outer conductor. The distributed capacitance is inversely proportional to the inner surface area (A inner )related.

[0005] A practical situation for connecting a coaxial cable to a terminal device is that in the joint area, the diameter d1 of the inner conductor is increased by inserting the inner conductor into the joint internal conductive member or by combining two inner conductors. The increase in the average diameter of the joint internal member in this area results in a lower characteristic impedance in this area. The characteristic impedance in this area can be maintained at the same value as the cable by proportionally increasing the diameter of the joint external conductor. However, this will result in an abrupt change in the diameter of the external conductor at the joint, which is not desired. Applicants have recognized the need for a joint assembly and a method of forming a joint, by which the characteristic impedance in the joint area can be maintained without requiring the diameter of the joint external conductor to be significantly increased starting from the outer diameter of the cable. Summary of the invention

[0006] Therefore, an object of the present invention is to provide a coaxial splicing assembly and a method for connecting a coaxial cable to a terminal device, which assembly and method can meet the above-mentioned needs, and the applicant believes that the assembly and method can at least alleviate the above-mentioned shortcomings, or can provide a useful alternative to known splicing assemblies, devices and methods.

[0007] According to the present invention, there is provided a coaxial splice assembly for permanently connecting a coaxial cable to a coaxial port or connection point of a terminal device, the port comprising an inner conductor and an outer conductor, the coaxial cable having a characteristic impedance Z0 and comprising an inner conductor and an outer conductor separated by a dielectric body, the outer conductor of the coaxial cable having an inner diameter D1, the coaxial splice assembly having a characteristic impedance Z0′, and comprising:

[0008] - an internal conductive structure having opposing first and second ends and an outer diameter, the two opposing ends being connectable to or connected to the coaxial cable and the internal conductor of the port, respectively;

[0009] - an electrically conductive outer tubular member having opposing first and second ends, an inner diameter D1′, a slot extending from the first end to the second end, the opposing first and second ends being connectable to the coaxial cable and the outer conductor of the port, respectively; and

[0010] - a dielectric arrangement located between the inner conductive structure and the conductive outer tubular member, the dielectric arrangement having an effective dielectric constant (ε eff ');in

[0011] -a) The effective dielectric constant (ε eff ') and b) at least one of the effective surface area of ​​the conductive outer tubular member is configured such that the difference between Z0 and Z0' is less than 3% and the variation between D1 and D1' is less than 5%.

[0012] The inner conductive structure may include a cylindrical member defining openings toward the first end and the second end, respectively, for receiving the inner conductor and the port of the cable, respectively.

[0013] The opening may be in the form of first and second slits extending from the first and second ends, respectively.

[0014] The opening may be in the form of an axially extending socket defined at the first end and the second end, respectively.

[0015] In other embodiments, the internal conductive structure may include overlapping end regions of the cable and the port, respectively, which are molded into a cylindrical structure with a moldable filler material to have the outer diameter.

[0016] The moldable filler material is preferably electrically conductive, and the cylindrical structure preferably has a constant outer diameter.

[0017] The dielectric arrangement may include a cylindrical body composed of a dielectric material, the cylindrical body defining a central hole therethrough.

[0018] The cylindrical body may include longitudinally separated first and second halves, each half defining a semicircular recess in a face facing the other half, and wherein the two semicircular recesses together form a bore.

[0019] The cylindrical body can further define a reduced effective dielectric constant (ε eff ′) to increase the characteristic impedance of the component.

[0020] The slots of the conductive outer tubular member may be longitudinal slots and may be angled greater than 90 degrees at the center of the conductive outer tubular member.

[0021] In a currently preferred embodiment, the included angle of the slot at the center is greater than 120 degrees.

[0022] The area toward at least one of the first and second ends of the electrically conductive outer tubular member may be pre-tinned or may include a solderable material.

[0023] The electrically conductive outer tubular member may be flexible.

[0024] The electrically conductive outer tubular member may be resiliently flexible.

[0025] Areas toward the first and second ends of the outer tubular member may define spaced apart windows.

[0026] The joining assembly may include a collapsible inner dielectric tube having a first wall thickness which, in use, accommodates and radially collapses an inner conductive structure mounted in a bore of the dielectric assembly and an outer conductive tubular member surrounding the dielectric assembly.

[0027] In use, the inner dielectric tube generates a contraction pressure which ensures ohmic contact between the conductive outer tubular member and the outer conductors of the cable and the port, respectively, and between the conductive outer tubular member and the inner conductors of the cable and the port, respectively.

[0028] The engagement assembly may further comprise a collapsible outer dielectric tube having a second wall thickness and, in use, the collapsible outer dielectric tube is mountable to receive the inner tube.

[0029] The outer dielectric tube is preferably longer than the conductive outer tubular member and, in use, extends over and overlaps the outer dielectric sleeve of at least one of the cable and the port to provide a gas-tight seal and mechanical reinforcement.

[0030] The first wall thickness may be greater than the second wall thickness.

[0031] At least one of the shrinkable inner tube and the shrinkable outer tube is heat shrinkable.

[0032] According to another aspect of the present invention, there is provided a method of connecting a coaxial cable to a port, the coaxial cable comprising an inner conductor and an outer conductor, the port comprising an inner conductor and a coaxial outer conductor, the method comprising the steps of:

[0033] - utilizing a coaxial joint assembly as defined above;

[0034] - arranging two regions, the two regions facing the first and second ends of the conductive outer tubular member, the first and second ends being pre-coated with a weldable material and arranging the outer conductors of the cable and the port, respectively, in overlapping relationship; and

[0035] - Using a coaxial heating device that applies a rated amount of heat energy to the two areas in a short time to melt and weld the two areas to the outer conductor of the cable and the port, respectively, but limiting damage to the dielectric component that is in contact with the conductive outer tubular component and the outer conductor of the cable and the port by limiting the rated amount of heat energy and the application time. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

[0037] Figure 1 is an exploded perspective view of an exemplary embodiment of a coaxial joint assembly;

[0038] Figure 2 is an exploded schematic diagram of a coaxial cable and a terminal device, the terminal device including a port or connection point having a coaxial conductor arrangement, and the cable and the port or connection point are to be permanently joined to each other by a coaxial splice assembly;

[0039] Figure 3 is along Figure 2 Cross-sectional view of midline III;

[0040] Figure 4is a cross-sectional view of an electrically conductive outer tubular member of an exemplary engagement assembly embodiment;

[0041] Figure 5 is a longitudinal cross-sectional view of a coaxial cable and a terminal device (in the form of a second coaxial cable) permanently joined or spliced ​​in an end-to-end relationship by an exemplary embodiment of a coaxial splicing assembly; and

[0042] Figure 6 is along Figure 5 Section view of midline VI. DETAILED DESCRIPTION

[0043] exist Figure 1 , an exploded view of an exemplary embodiment of the coaxial splice assembly 10 is shown.

[0044] refer to Figure 2 In use, the splice assembly 10 is used to permanently connect a coaxial cable 12 and a terminal device 14 to each other (as will be explained in more detail below). The terminal device includes a port or connection point 16 having a coaxial configuration or arrangement consisting of an inner conductor 18 and an outer conductor 20 separated by a dielectric 22. The terminal device 14 can be any device having a coaxial port or connection point, such as a second coaxial cable (e.g., Figure 5 The cable 24 shown, or any one of an RF connector, an RF electronic circuit, an antenna, a housing containing RF electronic equipment (all not shown), etc.

[0045] refer to Figure 3 As is known in the art, the coaxial cable 12 includes a center conductor (or inner conductor) 26 and an outer conductor 28 separated by a dielectric body 30. The coaxial cable has a characteristic impedance (Z0). The outer diameter of the center conductor is d1. The inner diameter of the outer conductor is D1.

[0046] refer to Figures 1 to 4, the coaxial joint assembly 10 has a characteristic impedance Z0′ and includes an internal conductive structure 32, the internal conductive structure 32 having opposite first and second ends 34.1 and 34.2. The first end 34.1 and the second end 34.2 are connectable to the inner conductor 26 of the coaxial cable and the inner conductor 18 of the port, respectively, or the first end 34.1 and the second end 34.2 are connected to the inner conductor 26 of the coaxial cable and the inner conductor 18 of the port, respectively. The internal conductive structure 32 has an outer diameter d1′ greater than d1. The joint assembly 10 also includes a conductive outer tubular member 36, the conductive outer tubular member 36 has an inner diameter D1′, a first end 38.1 and a second end 38.2, and a narrow slot 40 extending from the first end to the second end. The outer tubular member 36 has an effective inner surface area A′ inner The outer tubular member is connectable at a first end 38.1 thereof to the outer conductor 28 of the coaxial cable and at a second end 38.2 to the outer conductor 20 of the port. The junction assembly 10 also includes a dielectric arrangement 42 located between the inner conductive structure 32 and the conductive outer tubular member 36, the dielectric arrangement 42 having an effective dielectric constant (ε eff a) The effective dielectric constant (ε) of the conductive outer tubular member 36 eff ') and b) effective internal surface area A' inner At least one of is configured such that the difference between Z0 and Z0' is less than 3% and the variation between D1 and D1' is less than 5%.

[0047] In the exemplary embodiment shown, the internal conductive structure comprises a cylindrical member 32 defining axial slots 44.1 and 44.2 extending from its first and second ends, respectively, and for accommodating the inner conductor 26 and the inner conductor 18, respectively. Thus, at both ends of the member 32, resiliently flexible jaws for clamping the inner conductors are formed. In other embodiments, blind holes or sockets (not shown) extending from the respective ends may be provided to accommodate the inner conductors. In other embodiments (also not shown), the internal structure 32 may be formed by welding the inner conductors 26 and 18 in an overlapping manner with or without a separate conductive member 32 using a suitable filler metal. The welded area may be molded or formed to have a suitable, preferably circular cross-section having the outer diameter d1′. In this case, special molding tools and heating devices (for providing a short-duration heat pulse, but appropriately high heat energy) may be required.

[0048] The dielectric component 42 may include a cylindrical body composed of a dielectric material having a suitable dielectric constant and defining a central hole. The body is preferably longitudinally divided into a first elongated portion (or half) 50 and a second elongated portion (or half) 52. Each of the two halves defines a semicircular channel 54, which together form a central hole for accommodating the internal conductive structure 32 of the joint component 10. The two halves may further define an internal recess (or groove, or slot) 56 for air, thereby determining the ε of the component 42. eff In other embodiments, a suitable ε eff ' material, so that no recesses or slots are required.

[0049] The two halves 50, 52 can be used to squeeze the resiliently flexible jaws closed at the ends of the inner conductive cylindrical member 32 to ensure a consistent final diameter d1′ of the inner conductive member 32. This also ensures that the cable inner conductor 18 is clamped and achieves conductive engagement with the inner member 32. In addition, the two halves will allow insertion of the inner cylindrical member 32 after the inner cable 26 is connected to the inner cylindrical member 32.

[0050] like Figure 3 As shown, the slot 40 of the outer tubular member 36 is generally at an angle α greater than 90 degrees at the center 58 of the outer tubular member. In a preferred embodiment, α may be greater than 120 degrees. The width of the slot 40 determines A′ inner Applicants have unexpectedly discovered that for angles greater than 120 degrees, the inner surface area A' inside the conductive outer tubular member 36 inner There is a proportional relationship between and Z0′.

[0051] The outer conductive member 36 may be flexible or resiliently flexible to allow manual manipulation and insertion into the aperture (eg, Figure 5 4, 50, 52) and then it can be closed or partially closed around the dielectric assembly to enclose the assembly. To this end, the outer conductive member can define perforations. The narrow slots 40 in the outer conductive member 36 allow the member 36 to radially contract to force the two dielectric halves 50, 52 to radially push the jaws of the inner conductive member 32 to close and / or ensure a tight fit between the inner conductive member 32 and the dielectric assembly 42. The outer tubular member 36 can be further manipulated to pass or pass over the outer conductor 28 of the cable 12 and the outer conductor 20 of the terminal device, respectively, so that the areas toward the two opposite ends 38.1 and 38.2 of the outer tubular member overlap with the outer conductors 28, 20 (as shown in FIG. 4 ). Figure 520 ). These areas may be pre-tinned. These areas may also define perforations or spaced apart windows (not shown) that may facilitate connecting the outer tubular member 36 to the outer conductor 28 of the cable and the outer conductor 20 of the terminal device, respectively, as will be described in more detail below. Optionally, the outer tubular member may include a respective lip at each of its two opposing ends that may slide under the outer conductor 28 of the cable and the outer conductor 20 of the terminal device.

[0052] One method of connecting the above-mentioned overlapping end region of the outer tubular member 36 to the outer conductor 28 of the cable and the outer conductor 20 of the terminal device includes the use of a weldable sheet wrapped around the overlapping region and the above-mentioned special heating device.

[0053] The method therefore involves some pre-applied solder (tinning) or some "raw" solder that roughly conforms to the area to be joined, such as a thin solder sheet or cylindrical container made of solder. The heating device provides a cylindrical mold, which, after melting the solder, will ensure that the welding area forms a precisely sized ("molded") cylinder. The melting will be carried out using a "quantum" of thermal energy (Quantum = temperature difference * time). It is necessary to apply the required "quantum" in the shortest possible time. This is because heat is conducted very quickly from the welding area to the adjacent metal. The solder will melt once it is subjected to the effect of "quantum" > "quantum required to melt a given amount of solder". Applying heat in a short time (approximately 1 second) ensures that a) a minimum amount of the required energy of the applied rated Quantum is lost from the weld area, and b) a minimum amount of heat flows to other parts in contact with the weld area, and since both the internal conductive structure and the conductive external tubular member are in contact with the dielectric part, the temperature that will cause melting / deformation, which will change Z0, is minimized.

[0054] Another approach is to provide a protrusion (not shown) on the outer tubular member 36, wherein such a protrusion would allow the outer tubular member to be pressed over or under the cable outer portion 28, and such a protrusion would be shaped to resist movement in the opposite direction.

[0055] Another possible suitable method is to use a crimp sleeve (not shown) known to those skilled in the art.

[0056] The coaxial joint assembly 10 also includes a first heat shrinkable inner dielectric tube 60 having a first wall thickness and a second heat shrinkable outer dielectric tube 62 having a second wall thickness. The first wall thickness is preferably greater than the second wall thickness, and the second tube can be longer than the outer conductive tubular member. The outer dielectric tube can contain a heat-activated glue. The inner tube 60 and the optional outer tube 62 can be used as radial shrinking elements to achieve the necessary mechanical strength and conductive connection between the outer tubular member 36 and the outer conductors 28, 20, respectively. Each of the inner tube 60 and the outer tube 62 can include a single elongated tube segment.

[0057] The joint assembly 10 can be adapted to allow the connection (splicing) of two cables, but the two cables are not connected to the assembly at the same time. This may require that the dielectric assembly 42 and the outer tubular member 36 include two halves, each of which can be operated separately and independently without affecting the other half. This can be achieved by one or more of the following adaptations. The tubular member 36 can include some mechanical devices in its central area that allow the two halves to be opened and compressed on either side of the device without affecting the other half. This can be achieved by a member 36 that defines a transverse slit or includes some weak connection members that allow the movement of one half without generally forcing the other half to perform the same radial movement. However, tensile strength and conductivity must not be compromised. The dielectric assembly can also be divided into two axially extending end-to-end halves to allow independent manipulation of the two halves. The two halves can be hingedly connected to each other using a flexible or thin dielectric member or mesh. At least one of the inner tube 60 and the outer tube 62 may include at least a first elongated tube portion and a second elongated tube portion which, in use, are arranged in an end-to-end relationship and are heat shrinkably spaced apart from one another.

[0058] It should be understood that there are many variations in the details of the splice assembly defined and / or described herein. For example, the splice assembly may be modified to allow a coaxial cable to be connected to a port or connection point having a radial dimension different from that of the coaxial cable.

Claims

1. A coaxial splice assembly for permanently connecting a coaxial cable to a coaxial port or connection point of a terminal device, the port comprising an inner conductor and an outer conductor, the coaxial cable having a characteristic impedance Z0 and comprising an inner conductor and an outer conductor separated by a dielectric body, the outer conductor of the coaxial cable having an inner diameter D1, the coaxial splice assembly having a characteristic impedance Z0′ and comprising: - an internal conductive structure having opposing first and second ends and an outer diameter, the opposing two ends being connectable to the coaxial cable and the inner conductor of the port, respectively, or the opposing two ends being connected to the coaxial cable and the inner conductor of the port, respectively; - an electrically conductive outer tubular member having opposite first and second ends, an inner diameter D1′, a slot extending from the first end to the second end, the opposite first and second ends being connectable to the coaxial cable and the outer conductor of the port, respectively, and an effective inner surface area; and - a dielectric arrangement located between the inner conductive structure and the conductive outer tubular member, the dielectric arrangement having an effective dielectric constant ε eff ';in -a) the effective dielectric constant ε eff ' and b) at least one of said effective surface areas of said electrically conductive outer tubular member is configured such that the difference between Z0 and Z0' is less than 3% and the variation between D1 and D1' is less than 5%.

2. The coaxial joint assembly according to claim 1, wherein: The inner conductive structure includes a cylindrical member defining openings toward the first end and the second end, respectively, for receiving the inner conductor and the port of the cable, respectively.

3. The joint assembly according to claim 2, wherein: The opening is in the form of a first slit and a second slit extending from the first end and the second end, respectively.

4. The joint assembly according to claim 2, wherein: The openings are in the form of axially extending sockets defined at the first end and the second end, respectively.

5. The joint assembly of claim 2, wherein: The internal conductive structure includes overlapping end regions of the inner conductors of the cable and the port, the end regions being molded into a cylindrical structure with a heat-activatable moldable conductive filler material to provide a constant outer diameter while ensuring that the inner conductors achieve an ohmic bond.

6. A joint assembly according to any one of claims 1 to 5, wherein: The dielectric arrangement includes a cylindrical body composed of a dielectric material, the cylindrical body defining a central hole therethrough.

7. The joint assembly of claim 6, wherein: The cylindrical body comprises a first half and a second half separated longitudinally, each half defining a semicircular recess in a face facing the other half, and wherein the two semicircular recesses together form the hole.

8. A joint assembly according to any one of claims 6 and 7, wherein: The cylindrical body defines at least one additional slot or internal cavity that reduces the effective dielectric constant ε eff ' and thus increases the characteristic impedance of the component.

9. A joint assembly according to any one of claims 1 to 8, wherein: The slots of the outer tubular member are longitudinal slots having an included angle greater than 90 degrees at the center of the outer tubular member.

10. The joint assembly of claim 9, wherein: The included angle of the slot at the center is greater than 120 degrees.

11. A joint assembly according to any one of claims 1 to 10, wherein: Areas toward the first and second ends of the electrically conductive outer tubular member are pre-tinned or include a solderable material.

12. A joint assembly according to any one of claims 1 to 10, wherein: Areas toward the first and second ends of the electrically conductive outer tubular member define spaced apart windows.

13. A joining assembly according to any one of claims 1 to 12, comprising a shrinkable inner dielectric tube having a first wall thickness, and in use, the shrinkable inner dielectric tube radially shrinks the inner conductive structure and the outer conductive tubular member, the inner conductive structure is mounted in the hole of the dielectric assembly, and the outer conductive tubular member surrounds the dielectric assembly, thereby generating pressure in use, the pressure ensuring that the conductive outer tubular member respectively makes ohmic contact with the outer conductor of the cable and the port and the conductive outer tubular member respectively makes ohmic contact with the inner conductor of the cable and the port.

14. The splice assembly of claim 13, comprising a shrinkable outer dielectric tube having a second wall thickness and, in use, extending over the outer dielectric sleeve of at least one of the cable and the port to provide a gas-tight seal and mechanical reinforcement.

15. The joint assembly of claim 14, wherein: The outer tube contains a heat-activatable glue.

16. A joint assembly according to any one of claims 13 to 15, wherein: The first wall thickness is greater than the second wall thickness.

17. A joint assembly according to any one of claims 13 to 16, wherein: At least one of the shrinkable inner tube and the shrinkable outer tube is heat shrinkable.

18. A method of connecting a coaxial cable to a port, the coaxial cable comprising an inner conductor and an outer conductor, the port comprising an inner conductor and a coaxial outer conductor, the method comprising the steps of: - Utilization of a coaxial joint assembly according to any one of claims 1 to 17; - arranging two areas, the two areas facing respectively the first and second ends of the electrically conductive outer tubular member, the first and second ends being pre-coated with a weldable material and arranging respectively the outer conductor of the cable and the port in an overlapping relationship; and - using a coaxial heating device which applies a rated amount of heat energy to the two areas in a short time in order to melt and weld the two areas to the outer conductor of the cable and the port, respectively, but which limits damage to dielectric components in contact with the conductive outer tubular component and the outer conductor of the cable and the port by limiting the rated amount of heat energy and the application time.

19. The method according to claim 18, insofar as it is dependent on claim 5, comprises the following steps: Thermal energy is applied using the coaxial heating apparatus to activate the moldable conductive filler material to provide a constant outer diameter while ensuring that the inner conductor achieves an ohmic bond.

20. The method according to claim 19, wherein: The steps of a) applying a rated amount of thermal energy to both of said regions and b) applying thermal energy to activate said moldable conductive filler material are performed simultaneously.

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