Grounding Foil

Abstract

The invention comprises a grounding foil member having one or more cavities therein, formed of tangs for securing circuit elements such as filters thereto by means of direct contact. The outer edge of the foil member which contacts the inner shell of a conductor is formed of flaps bent at an angle. Each of the flaps deflect upon entering the shell which completes the electrical circuit between the filter and the shell through the ground foil. The filter may be removed from the ground foil and the ground foil from the shell with relative ease and with no soldering required.

Description

GROUNDING FOIL

The invention relates in general to grounding foils and more particularly to a device for mounting an element in a conductor having a ground connection therebetween.

BACKGROUND OF THE INVENTION

Filters are used in coaxial lines to attenuate unwanted signals such as radio frequency interference signals commonly called RFI signals. Normally such a filter is a low pass filter which shunts the unwanted signals to ground. Most coaxial line filters are soldered to a ground plane and then the ground plane is then soldered, swaged or welded to the shell or outer conductor of the coaxial line. Alternatively, a leaf spring may be soldered to the filter or a spring may be installed in each filter cavity and then potting used to hold the filters in the connector. Still another approach is to solder the filter to the contact and insert the filter into the ground plane and finally soldering this filter-contact assembly to the ground plane.

Drawbacks to the above mentioned techniques are numerous. For example when a filter is soldered to the ground plane, the connector assembly and filters become extremely difficult to rework or change. In effect, once the filter is soldered to the ground plane, the connector becomes a nonrepairable assembly. Further, the quality of the ground connection between the filter and the ground plane is not known until the assembly of the connector is completed and tested. Thus, when the ground connection is poor, the connector assembly must undergo extensive reworking in order to obtain a good ground contact. Moreover, component and assembly costs are high due to the physical soldering of the filters and jig boring or die casting is required to manufacture the ground plane.

In order to overcome the attendant disadvantages of prior art filter connections, the grounding foil of the present invention eliminates the need for soldering the filter to the ground plane. The filter may be installed and removed with relative ease due to the physical contraction of the grounding foil. Further, good contact is maintained at all times on the outside diameter of the filter and the inside diameter of the outer coaxial conductor. Since the filter ground foil is not soldered to the shell, a connector assembly using the grounding foil, can be reworked with ease. Thus, potting is not required in the connector and other physical means can be employed to retain the insulators and other components in the shell. Moreover, the grounding foil can be metal stamped or metal formed from an electroetching, thus its cost is relatively competitive in comparison to a conventional ground plane which is made by jig boring or die cast tooling.

SUMMARY OF THE INVENTION

More particularly, the invention comprises a ground foil member made of lightweight material such as a single piece of the beryllium copper which may be plated with silver to reduce the contact resistance between contact points. Within the foil member are one or more cavities wherein electrical elements are retained and grounded by the foil. Each of the cavities are formed from a plurality of short tangs which are bent to form a funnel. The tangs taper inward to block or close the inside diameter of each cavity. Each tang operates independent of the other tangs and when the electrical element is inserted, they deflect over the outside diameter of the electrical element. The outer edge of the foil member has means for securing the ground foil to a conductor providing a ground connection between the electrical elements and the conductor.

The advantage of the invention, both as to its construction and mode of operation, will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like referenced numerals designate like parts throughout the FIGS.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view partly in section of a preferred embodiment of the invention; and

FIG. 2 is a side view, partly in section, of the device of FIG. 1, disassembled.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is shown in FIG. 1 a filter ground foil 12 mounted in a shell 14, which may be the outer conductor of a coaxial line, the shell having a mounting flange 16 which may be secured to a rigid structure by means of a nut (not shown) passing through the hole 18 in the flange.

The filter ground foil is generally circular in shape and has a diameter slightly less than the inner diameter of the shell 14 at the point where the foil is to be mounted. Secured along the outer periphery of the foil are a plurality of flaps 22 bent at an angle of 30.degree. prior to insertion into the shell. Each of the flaps deflect upon entering the connector shell and keep a constant pressure and contact with the inside of the shell.

A plurality of individual cavities 24 are formed on the grounding foil. Each of the cavities contain a plurality of short tangs 26 (three are shown for illustration purposes in the drawings) which are bent initially at an angle of 15.degree. to form a funnel. Each tang operates independently of the others and when an element such as a filter 28 is inserted in the funnel formed by the tangs 26, the tangs deflect over the outside diameter of the filter. Each tang is limited in the amount of deflection due to the fiber stresses generated when the tang deflects; however, this deflection can be increased depending upon the size of the filter and the deflection required to maintain contact with the filter. Thus, each tang acts like a spring, applying constant pressure to the outside diameter of the filter. When the filter is removed, the tangs return to their normal position, ready to accept another filter of a different outside diameter tolerance.

The filter 28 used in combination with the ground foil is of conventional design having a pin 32 at one end and a pin contact 34 at the other end. However, the filter shown in the drawing is for illustrative purposes only, it being understood that other arrangements or circuit elements could be used in place of the depicted filter 28.

Referring now to FIG. 2, there is depicted, the arrangement of FIG. 1 prior to assembly. As can readily be seen, the tangs 26 are in their normal positions at an angle of 15.degree. with respect to the main ground foil body prior to insertion of the filter 28. Further, the flaps 22 are at a 30.degree. angle prior to insertion of the grounding foil into the shell 14. It should be understood, of course, that the angles mentioned are merely a matter of design and not limiting, the exact choice of angles being dependent upon the exact usage of the grounding foil.

As can readily be seen, the entire assembly and disassembly does not require soldering or other mechanical methods to maintain good electrical contact between the shell and the filter through the grounding foil; and the filters can be replaced, added, or removed from the connector without difficulty and at relatively minor costs.

The grounding foil can be used in any filter connector that employs a circular filter. Of course, with minor modifications, other shaped filters could be used. Moreover, with slight modification of the grounding foil, other shaped connectors such as elliptical, rectangular, or square shapes could be used.

Further, while the grounding foil has been described as being made of beryllium copper which has been plated with silver, it should be understood that the grounding foil also could be made out of any conductive material which can act like a spring, such as brass or stainless-spring steel. Also, insulating plugs may be utilized within the member 14 to support the member 28 or as a stop for the member 12.

It should be further understood that the foregoing disclosure relates only to the preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention.

Claims

We claim:

1. In combination a grounding foil retaining removable electrical elements within a conductor and providing a ground connection between said elements and said conductor; said grounding foil being of resilient sheet metal and comprising:

a foil member whose outer dimensions are slightly smaller than the confines of said conductor, said foil member having a plurality of tabs extending therefrom resiliently engaging the inner surface of said conductor;

means on said foil surface defining a plurality of cavities each formed from a plurality of short tangs, said tangs deflecting over said electrical element with said electrical element inserted in said cavity; and

said tangs being angularly disposed with respect to a plane defining the surface of said foil adjacent said tangs prior to insertion of said elements in said cavity.

2. A grounding foil in accordance with claim 1 wherein the outer edge defined by said tabs is slightly greater than said inner dimension of said conductor, said tabs deflecting upon insertion of said foil into said conductor, thereby providing a constant pressure and contact between said foil and said conductor.

3. A grounding foil in accordance with claim 1 wherein each of said cavity tangs acts independently of the other tangs of a cavity applying constant pressure to the outer surface of an electrical element; and upon removal of said electrical element from said cavity, said tangs being capable of returning to their normal position.

4. A grounding foil in accordance with claim 1 wherein said grounding foil is a thin flat member and is mounted in said conductor in a plane perpendicular to an axis defined by said conductor.

5. A grounding foil in accordance with claim 4 wherein said grounding foil is made of beryllium copper plated with silver.