# US 4,399,316 A · Non-contacting RF shielding device

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- Number: US 4,399,316 A
- Document ID: US4399316A
- Status: Granted
- Kind: A
- Application number: 06/279,181
- Filed: 1981-06-30
- Granted: 1983-08-16
- Earliest claimed: 1981-06-30
- Assignees: RCA Corporation
- Inventors: Oakley M. Woodward
- Web page: https://patentgrep.com/patent/US4399316A

## CPC

- H05K 9/0073: {Shielding materials (H05K9/0003 takes precedence)}
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A non-contacting RF shielding means is provided to inhibit the flow of energy in a given frequency band through an interface area between two conductive surfaces. A series of stub-like members are provided which are open circuited at one end and connected to a common conductive member on the other end. A portion of the first conductive surface is spaced from the stubs such that a plurality of microstrip lines are formed. The open circuits at the one end of the stubs reflect back as low impedance paths between the first surface and the other end of each of the stubs. The common conductive member is coupled to the second conductive surface. The arrangement thus provides a plurality of low impedance paths between the first and second conductive surfaces in the given frequency band without direct physical contact between the two conductive surfaces.

## Claims

### Claim 1

In combination:
a first conductive surface for providing electrical shielding;
a second conductive surface for providing electrical shielding, said second surface having at least a portion thereof continguous with at least a portion of said first conductive surface but not in direct electrical contact therewith, thereby creating an interface area, said interface area allowing the flow of energy therethrough in a given frequency band whereby said shielding is rendered less effective;
a plurality of elongated conductive stub-like members positioned in said interface area, a first end of each of said stub-like members being directly connected to a common conductive member and each of said stub-like members being spaced at a given distance from at least a portion of said first conductive surface such that said stub-like members and said first conductive surface form a plurality of microstrip lines open-circuited at the second end of each stub-like member remote from said first end;
each of said stub-like members being dimensioned such that said open circuits at said second ends are transformed into low impedance paths in said given frequency band, said paths effectively occurring between said portion of said first conductive surface and respective points in the vicinity of said first ends of said stub-like members without direct conductive contact between said first conductive surface and said respective points in the vicinity of said first ends of said stub-like members; and
means adapted for coupling said common conductive member to said second conductive surface.

### Claim 2 (depends on 1)

The apparatus according to claim 1 wherein each of said plurality of stub-like members comprises a first conductive section extending from said common conductive member and at least a second conductive section extending perpendicularly from said first section.

### Claim 3 (depends on 1)

The apparatus according to claim 1 wherein each of said plurality of stub-like members has a total length from one end to the other end which is substantially a quarter wavelength long at a frequency in said given band.

### Claim 4 (depends on 1)

The apparatus according to claim 1 wherein said two conductive surfaces comprise inner surfaces of a box-like device and said interface area comprises a seam separating said inner surfaces.

### Claim 5

Apparatus for reducing the propagation of energy through an interface area between two conductive surfaces, said apparatus comprising:
a first plurality of conductive stub-like members adapted for being positioned in proximity to one conductive surface;
a second plurality of conductive stub-like members adapted for being positioned in proximity to said second conductive surface;
connecting means for electrically and mechanically connecting at least one stub-like member of said first plurality to at least one stub-like member of said second plurality, said first and second plurality of stub-like members and said connecting means being formed on an elongated strip of dielectric material;
said first plurality of stub-like members forming a plurality of low impedance paths in a given frequency range between said connecting means and one of said conductive surfaces when positioned in proximity to said one conductive surface;
said second plurality of stub-like members forming a second plurality of low impedance paths in said given frequency range between said connecting means and the other of said conductive surfaces when positioned in proximity to said other conductive surface.

### Claim 6 (depends on 5)

The apparatus according to claim 5 wherein said first and second plurality of stub-like members and said connecting means are formed from copper and said dielectric strip is formed from Mylar.