Insulator for a coaxial cable connector and method of use thereof

An insulator for coaxial cable connectors, the insulator is disposed within a coaxial cable connector and contains an insulator passageway. The insulator has a guide surface at one end. As the prepared end of a coaxial cable is inserted into the insulator passageway, the guide surface engages the dielectric of the cable and radially diverts the conductive foil sheath away from the center conductor of the cable.

FIELD OF THE INVENTION

The invention relates to coaxial cable connectors, and more specifically, to an improved insulator for a coaxial cable connector and a method of use thereof.

BACKGROUND OF THE INVENTION

The use of coaxial cable for video and data transfer is rapidly increasing. Such cables typically include a center, inner conductor surrounded by a low dielectric constant plastic foam. An outer conductor is typically bonded to the outer surface of and thereby contains the dielectric. The outer conductor may comprise a sheath of fine braided metallic strands, a metallic foil, or multiple layer combinations of either or both. A protective insulating jacket, or sheath surrounds the outer conductor and helps prevent moisture from degrading the signal path. The ends of such coaxial cables must be connected to junction boxes, amplifiers, coaxial ports and the like and coaxial connectors are well known for terminating the ends of coaxial cables.

In order to properly transmit an electrical signal, a coaxial connector should ensure that a reliable electrical connection is achieved between the outer body of the connector and the outer conductor of the coaxial cable. Likewise, a suitable coaxial connector must achieve a reliable electrical connection between the conductive pin of the connector and the center conductor of the coaxial cable. In addition, reliable coaxial connectors must form a secure mechanical connection to the end of the coaxial cable, since mechanical separation of the connector from the end of the cable will interfere with successful transmission of the desired electrical signal.

Before attaching the end of a coaxial cable to a connector, the end of the coaxial cable must be prepared. This is typically done by cutting the dielectric and the outer conductor of the cable for a short distance to expose a short segment of the center conductor. The braided metallic strands of the outer conductor may be folded over the jacket while the conductive foil remains bonded to the dielectric.

Once the coaxial cable is prepared, the prepared end is inserted into the connector until the dielectric material and conductive foil engages the insulator and the center conductor engages the conductive pin. Previous insulators typically only have a shoulder or an inner chamfer where the dielectric material and conductive foil meets the insulator. In these types of insulators, the conductive foil can become diverted inwardly toward the center conductor during installation. When the conductive foil is diverted inwardly towards the center conductor, it can affect the impedance matching of the connector or cause a signal short if the conductive foil contacts the center conductor. This in turn affects performance parameters, such as return loss or a failure to transmit the desired electrical signal.

It would be a great advantage to provide an insulator for coaxial cable connectors that overcomes the above problems and disadvantages.

SUMMARY OF THE INVENTION

Briefly stated, an insulator for a coaxial cable connector, the insulator extending along a longitudinal axis and having defined therein an insulator passageway, the insulator having a first end and a second end, the first end of the insulator having a guide surface defined thereon, whereby the guide surface terminates at the first end at a projection.

According to an embodiment of the invention, a connector for a coaxial cable, the coaxial cable having a center conductor surrounded by a dielectric material, the dielectric material surrounded by a conductive foil sheath, the connector comprising: a connector body having a first end and a second end, the connector body extending along a longitudinal axis and having defined therein an internal passageway; and, an insulator disposed within the internal passageway, the insulator having an insulator passageway configured to receive the center conductor, the insulator further having a insulator first end and an insulator second end, the insulator first end having a guide surface defined thereon, the guide surface configured to radially divert the conductive foil sheath away from the center conductor.

According to an embodiment of the invention, a method for attaching a coaxial cable to a connector, the coaxial cable having a center conductor surrounded by a dielectric material, the dielectric surrounded by a conductive foil sheath, the connector having an internal passageway defined therein, the connector further having an insulator having a guide surface defined at one end, the insulator disposed within the internal passageway, the insulator having an insulator passageway, comprising the steps of: inserting the cable into the internal passageway, whereby a portion of the center conductor is disposed in the insulator passageway; engaging the dielectric with the guide surface configured to radially divert the conductive foil sheath away from the center conductor.

According to an embodiment of the invention, a connector for a coaxial cable, the coaxial cable having a center conductor surrounded by a dielectric material, the dielectric material surrounded by a conductive foil sheath, the connector comprising: a connector body having a first end and a second end, the connector body having defined therein an internal passageway; and, an insulator disposed within the internal passageway, the insulator having an insulator passageway configured to receive the center conductor, the insulator further having a first end and a second end, the first end having a first inner diameter and a first outer diameter, an guide surface defined between the first inner diameter and the first outer diameter, the guide surface configured to radially divert the conductive foil sheath away from the center conductor; a conductive pin partially disposed within the insulator passageway, the conductive pin configured to receive the center conductor; a post disposed within the internal passageway, the post having a post passageway configured to receive the coaxial cable; and, a compression sleeve positioned at the first end of the connector body for engagement with the post, the compression sleeve having a compression sleeve passageway configured to receive the coaxial cable, wherein axial advancement of the compression sleeve causes a deformable sleeve to radially inwardly compress the coaxial cable against the post.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

With reference toFIG. 1A, a coaxial cable10is shown prior to preparation for installation into a coaxial cable connector20(SeeFIGS. 2 and 3). Coaxial cable10includes a center conductor12, typically formed of copper, copper-clad steel or aluminum, which is surrounded by a low dielectric constant, insulator material14, such as plastic foam and the like. An outer conductor16typically is bonded to the outer surface of and thereby contains the dielectric14and embedded center conductor12. Outer conductor16can comprise a sheath of fine braided metallic strands, a metallic foil, or multiple layer combinations of either or both.FIG. 1Bshows a multiple layer combination where outer conductor16has a metallic conductive foil17and fine braided metallic strands19. A flexible, plastic jacket18surrounds outer conductor16to seal the cable from the environment and provide additional stiffness and mechanical protection to cable10.

FIG. 1Bshows the typical preparation of the end of cable10prior to insertion into a coaxial cable connector by selectively removing various layers to progressively expose an end of center conductor12, an end of dielectric14and an end of the conductive foil17. A portion of braided metallic strands19has been folded back over jacket18.

FIG. 2shows a typical 7/16 inch DIN male type coaxial cable connector20. The selection of this particular type of connector is for illustrative purposes only, and it is understood by one of ordinary skill in the art that a particular type of connector is not required for the present invention.

FIG. 3is a cross-section of connector20shown inFIG. 2. Connector20includes a connector body22with an internal passageway28for receiving cable10. A nut30is connected to connector body22via an annular flange. An o-ring24disposed between nut30and connector body22provides a seal to prevent moisture, dust, and the like from entering the connector. An insulator40positions and holds a conductive pin32within connector body22. Insulator40may have an internal passageway44for receiving conductive pin32. Conductive pin32receives center conductor12upon installation of cable10and establishes electrical conductivity between the center conductor and the mating port (not shown).

With further reference toFIG. 3, connector20includes a post34configured to receive the center conductor12, dielectric14and conductive foil17of cable10. Tip35of post34is configured to pass between the conductive foil17and the braided metallic strands19. A portion of braided metallic strands19and jacket18fits into cavity37. During installation, compression sleeve38is axially advanced into cavity36and is configured to compress a deformable sleeve39. Deformable sleeve39compresses braided metallic strands19and jacket18against post34, thereby securing the cable in the connector.

With reference toFIGS. 4 and 5, a side elevation and cross-sectional view of insulator40is shown. Insulator40has a first end40aand a second end40b. Insulator40includes an insulator passageway44for receiving the conductive pin32. Insulator first end40aincludes an insulator first inner diameter46and an insulator first outer diameter48, with a guide surface42formed in-between. Guide surface42may terminate at one end at a projection50.

Referring toFIG. 6, the prepared end of cable10has been partially inserted into connector20having insulator40with one embodiment of a guide surface42. As cable10is fully inserted into connector20(SeeFIG. 7), the portion41of guide surface42engages the dielectric14, causing a portion of the dielectric14to bend or deform slightly. The slight bending or deformation of a portion of dielectric14radially diverts the conductive foil17away from the center conductor. This radial diversion of the conductive foil17occurs prior to the compression sleeve38being advanced into the connector body20.

Referring toFIG. 8, guide surface42may take various forms, including a ramped or tapered surface, or various shapes such as convex or arcuate.FIG. 8Ashows an arcuate surface,FIG. 8Bshows a ramped surface,FIG. 8Cshows a tapered surface, andFIG. 8Dshows a convex surface.

While the present invention has been described with reference to a particular preferred embodiment and the accompanying drawings, it will be understood by those skilled in the art that the invention is not limited to the preferred embodiment and that various modifications and the like could be made thereto without departing from the scope of the invention as defined in the following claims.