1. Field of the Invention
The invention relates to an improved cable-connector system, and more particularly to a system comprising: 1) a low cost, high performance, water blocking aluminum cable as described in U.S. utility patent application Ser. No. 10/131,747 filed Apr. 24, 2002 also assigned to Andrew Corporation and hereby incorporated by reference in its entirety, and 2) a low cost, high performance water-blocking connector uniquely configured to mate with such low cost aluminum cable.
As described in detail in the '747 application, no known cable product exists which met all four of the desired foam coaxial cable attributes: 1) low cost comparable to braided cable cost; 2) electrical properties including shielding effectiveness and intermodulation suppression comparable to that of solid tubular shielded cable; 3) mechanical properties, primarily flexibility, comparable to braided cable; and 4) water blockage comparable to annular corrugated cable.
The unique capabilities of the aforesaid cable were achieved by a novel combination of cable materials, manufacturing methods and cable structural configurations. The very low cost of the cable was achieved in part by the use of an outer conductor composed of aluminum or aluminum alloy. The use of aluminum provides enhanced water blockage by permitting the helical outer conductor during formation to be permanently deformed into the foam insulator material, thus eliminating air gaps at the corrugation crests of the cable and providing a moisture seal.
The manufacturing cost of the cable was dramatically reduced in part by using a dual lead helix on the corrugation, permitting the cable line speed to be doubled. One aspect of the present invention is to provide a connector for such a cable which complements the cable by offering low cost of manufacture, excellent electrical performance and moisture blockage, secure cable retention, and superior ease and speed of field installation.
The unique dual lead helical corrugations and aluminum construction of the cable outer conductor presents first-ever challenges to the connector designer. The dual helical corrugation creates two separate and independent helical grooves which must each be sealed to prevent moisture migration. The use of aluminum as the material for the outer conductor, being much softer and more ductile than conventional copper and copper alloys, has to be treated differently in designing a crimp type connector to prevent over deformation of the outer conductor which could degrade electrical performance of the cable.
To better understand the construction of a dual lead helical cable corrugation, reference may be had to
A dual lead coaxial cable 180 of the type preferred for use in the system of the present invention is depicted in FIG. 13. The dual lead coaxial cable 180 of FIG. 13 also has an inner conductor 220, a foam insulator dielectric 210 that surrounds the inner conductor 220, and an outer conductor 200 surrounding the dielectric 210. The outer conductor 200 may be a thin strip of ductile material with a longitudinal high frequency weld seam. The outer conductor 200 has dual lead corrugations 197 which tightly compress the dielectric 210. The compression of the dielectric 210 substantially eliminates the formation of fluid propagating air gaps and passageways between the outer conductor 200 and the dielectric 210. The dual lead coaxial cable 180 may also have a jacket 190 that surrounds the outer conductor 200. The angle 198 is the pitch angle of the outer conductor dual lead corrugations 197 which is twice the pitch angle of a single lead helical corrugation 196.
It will be understood from
The chief competition for the novel cable-connector system of the present invention is the various braided cable systems. Braided cable suffers from electrical and water blockage performance which is inferior to the low cost corrugated cable described. Further, as will become evident from the ensuing description of the connector of the present invention, braided cable connectors are much more difficult to attach to the cable, requiring elaborate cable preparation in some cases. They are more expensive to manufacture than the present connector as they all require that the connector body provide an inner ferrule against the electrically conductive braid or foil is compressed to retain the connector on the cable. Means for moisture-blocking the connector may be integrated into or separate from the means for compressively securing the connector on the cable.
The connector of the present system, in contrast offers a relatively simple and low cost approach to securely installing the connector on the cable and preventing moisture invasion into the connector and attached cable. As will be described at length below, the connector of the present invention does not require an inner ferrule against which a braid or foil is compressed to hold the connector on the cable. In one embodiment, internal helical grooves formed in the hollow inner connector body of the connector enable the connector to be simply screwed onto mating corrugations of the cable outer conductor until the connector reaches a stop. To prevent the cable from inadvertently unscrewing or backing out, the connector body is crimped down on the corrugated outer conductor. This prevents the cable from rotating while in use or during assembly, solidly locking the connector permanently onto the cable.
In other embodiments, the internal bore of the connector body which receives the corrugated cable body may be ribbed longitudinally or circumferentially, roughened or otherwise perturbed in other ways such that when the connector body is crimped down on the outer conductor of the cable, it cannot unscrew or otherwise back out.
In preferred embodiments, as will be explained, the connector body is provided with radial external ribs which reduce and control the amount of force required to deform the connector body. The crimping of the connector body is accomplished with a conventional crimping tool having a hexagonal clamp opening.
In accordance with a feature of the present invention, because of the use of the connector with a cable having a an outer conductor composed of soft, ductile aluminum or aluminum alloy, the ribs may be varied in length and/or width to define a deformation profile on the connected cable which permanently secures the cable in the connector, but also optimizes electrical performance and moisture blockage.
The connector component of the system will now be described in detail. It should be understood that while the connector is most advantageously used with the described low-cost cable having a dual lead helically corrugated aluminum outer conductor, the connector may be employed also with other corrugated cables.
2. Description of Related Connector Prior Art
Connectors for corrugated outer conductor cable are used throughout the semi-flexible corrugated coaxial cable industry.
Competition within the cable and connector industry has increased the importance of minimizing installation time, required installation tools, and connector manufacturing/materials costs.
Previously, connectors have been designed to attach to coaxial cable using solder, and or mechanical compression. The quality of a solder connection may vary with the training and motivation of the installation personnel. Solder connections are time consuming and require specialized tools, especially during connector installation under field conditions. Mechanical compression connections may require compressive force levels that are excessive for field installation, and or special tooling that may not be portable or commercially practical for field installation use. Mechanical compression designs using wedging members compressed by tightening threads formed on the connector may be prohibitively expensive to manufacture.
The corrugation grooves of helically corrugated coaxial cable may provide a moisture infiltration path(s) into the internal areas of the connector and cable interconnection. The infiltration path(s) may increase the chances for moisture degradation and or damage to the connector, cable, and or the connector and cable interconnection. Previously, O-rings or lip seals between the connector and the cable outer conductor and or jacket have been used to minimize moisture infiltration. O-rings may not fully seat/seal into the bottom of the corrugations and lip seals or O-rings sealing against the jacket may fail over time if the jacket material deforms.
Heat shrink tubing has been used to protect the connector and cable interface area and or increase the rigidity of the connector/cable interconnection. However, the heat shrink tubing may not fully seal against the connector body, increasing the moisture infiltration problems by allowing moisture to infiltrate and then pool under the heat shrink tubing against the outer conductor seal(s), if any.
Therefore, it is an object of the invention to provide a coaxial connector that overcomes deficiencies in the prior art.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
a shows an external side and partial section view of an embodiment of the invention having an internal crimp area helical grooved section.
b shows an external side and partial section view of an embodiment of the invention having varied height crimp area ridges.
c shows an external side and partial section view of an embodiment of the invention having internal crimp area axial grooves.
d shows an external side and partial section view of an embodiment of the invention having internal crimp area radial grooves.
e shows an external side and partial section view of an embodiment of the invention having internal crimp area radial ridges.
f shows an external side and partial section view of an embodiment of the invention having internal crimp area perturbations.
a shows a section side view of a body portion of the embodiment of the invention shown in FIG. 1.
b shows an external side view of a body portion of the embodiment of the invention shown in FIG. 1.
a shows a side section view of an inner contact of the embodiment of the invention shown in FIG. 1.
b shows an external side view of an inner contact of the embodiment of the invention shown in FIG. 1.
a shows a cross section view of a gasket of the embodiment of the invention shown in FIG. 1.
b shows an external side view of a gasket of the embodiment of the invention shown in FIG. 1.
One embodiment of a crimp connector, for example a type N connector, is shown in
As shown in
As previewed above, a helical groove section 50 of the embodiments shown in
The dual lead coaxial cable 180, as shown for example in
The helical groove section 50 increases the contact surface area between the cable outer conductor 200 and the body 30 in the crimp area 100, thereby improving the electrical characteristics of the connection between the body 30 and the outer conductor 200. Also, during installation, the connector 1 is initially threadably retained upon the dual lead coaxial cable 180.
Although the helical groove section 50 is preferred for optimizing electrical interconnection, accurately forming the helical groove profile of the helical groove section 50 may require advanced machining equipment and or casting methods that may make the body 30 comparatively expensive for some applications and or connector types. Examples of simplified alternative mating section structures are shown in
The body 30 may be formed from, for example brass or other metal alloy. To minimize corrosion and or dissimilar metal reactions with the connector end 10 and or the outer conductor 200 of the dual lead coaxial cable 180, the body 30 may have a corrosion resistant plating, for example, tin or chromium plating.
A cable end shoulder 80 may be added to the body 30 for seating a gasket 90 or an application of sealant, described herein below.
Compared with braided cable systems, the present invention facilitates rapid and foolproof field installation. A dual lead coaxial cable 180 may be prepared for attaching the crimp connector 1 by exposing an appropriate length of the cable's inner conductor 220 and by removing any outer jacket 190 from a section of the outer conductor 200. A gasket 90 may be screwed upon the outer conductor 200 and the crimp connector 1 may then be hand threaded onto the dual lead coaxial cable 180 until the cable's outer conductor 200 impacts upon a stop 60 that extends radially inward across the radial depth of the body 30. When the leading edge of the cable outer conductor 200 contacts the stop 60, further threading may partially collapse/compress the cable outer conductor corrugations into a deformation groove 70. The connector 1 is then electrically interconnected and physically secured upon the dual lead cable 180, without requiring field application of solder or conductive adhesive, by applying a crimp in the crimp area 100 sufficient to deform the internal helically grooved section 50 to a point where the dual lead cable 180 may not be unthreaded.
If alternatives to the helical grooved section 50, as shown for example in
The outer diameter of the crimp area 100 may be adjusted to mate with, for example, industry standard hexagonal crimp hand tools by adjusting the radius and or width of the crimp area 100.
A plurality of ridges 105 may be formed in the crimp area 100. The depth and width of grooves between the ridges 105 may be selected to adjust the compressive force required to compress and or deform the, for example, internal helical groove section 50 and outer conductor 200 of the dual lead coaxial cable 180 during the crimp operation and also to create a corresponding retentive strength of the compressed material once crimped.
In alternative embodiments, the ridges 105 may be formed with varied heights for example to form a barrel shaped profile with a middle peak. As shown in
During the threading of the connector 1 onto the helical corrugations in the outer conductor 200 of the dual lead coaxial cable 180, the inner conductor 220 is inserted into an inner contact 110 (
A socket contact section 120 on the cable end 20 of the inner contact 110 may be formed with a cable end 20 diameter smaller than an outer diameter of the inner conductor 220. A plurality of slits 130 may be formed in the socket contact section 120 to allow the socket contact section 120 to easily flex and accommodate the inner conductor 220 upon insertion, creating a secure electrical connection without requiring, for example, soldering or conductive adhesive.
The inner contact 110 may be formed from a spring temper material, for example beryllium copper, phosphor bronze or other metal or metal alloy with suitable spring/flex characteristics. The inner contact 110 may be given a low contact resistance surface treatment, for example, gold or silver plating to increase conductive characteristics and negate dissimilar metal reactions with the center conductor of the dual lead coaxial cable and or other connectors. The appropriate length of exposed inner conductor 220, mentioned above, may be a length that results in the inner conductor 220 being inserted into the socket contact section 120 short of contacting a depression 140 when the outer conductor 200 of the dual lead coaxial cable 180 has fully seated against the stop 60 and any compression of the outer conductor 200 into the deformation groove 70 is completed.
As shown in
As shown in
As described, the crimp connector 1 provides the following advantages. The crimp connector 1 has a limited number of components and may be cost effectively assembled with only a few manufacturing operations. Further, the crimp connector 1 may be installed in the field, without requiring soldering or conductive adhesives, using only industry standard hand tools. Also, the crimp connector 1 may be used with dual lead coaxial cable 180 to form a cable/connector interconnection with a high level of moisture infiltration resistance. When heat shrink tubing 170 is applied to the crimp connector 1, an improved seal is created and the cable/connector interconnection has increased rigidity.
The cable-connector system of the present invention in its preferred execution offers a unique combination of features: 1) low manufacturing cost due to the low-cost dual lead helically corrugated aluminum cable and low-cost connector; 2) excellent moisture blockage attributable to the inherent superior moisture resistance of the cable, the dual lead helical groove compression gasket and unique high-surface-area, crimp-on-threads feature of the joint between the connector and cable; 3) permanent attachment of the connector and cable by the crimping of the connector onto a helically corrugated cable; 4) simplified and foolproof field installation enabled by the dry, secure, and unmistakable connection made with very few steps, minimal cable or connector preparation, lack of easy-to-lose extra parts and standard hand tools; and 5) excellent electrical performance.
Where in the foregoing description reference has been made to ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.
This application is a continuation-in-part of application Ser. No. 10/248,741, filed Feb. 13, 2003, owned by the assignee of the present application, Andrew Corporation of Orland Park, Ill.
Number | Name | Date | Kind |
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4990106 | Szegda | Feb 1991 | A |
5141451 | Down | Aug 1992 | A |
5154636 | Vaccaro et al. | Oct 1992 | A |
5281167 | Le et al. | Jan 1994 | A |
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6575786 | Khemakhem et al. | Jun 2003 | B1 |
Number | Date | Country | |
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20040161970 A1 | Aug 2004 | US |
Number | Date | Country | |
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Parent | 10248741 | Feb 2003 | US |
Child | 10249112 | US |