To improve shielding of flat multicore cables, a thin, seamless ferrous shield around all cores optimizes low frequency magnetic shielding. Such shielding is covered with an ultrathin seamless coat of highly conductive nonferrous material

Drechsler, R. J.

English

NASA Technical Reports Server

Dielectric
Figure 1. Present Configuration 
Dielectric	 Conductor(s) 
Figure 2. Proposed Configuration 
.
September 1969
	 Brief 69-10401 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Improved Ferrous Shielding for Flat Cables 
The problem: 
To improve the shielding of flat multicore cables. 
At present a typical cable (Figure 1) is a dielectric 
sandwich containing the cores shielded on one or 
both broad sides by a nonferrous plate; the narrow 
edges are not shielded. Such shielding is effective 
electrostatically, but not magnetically throughout the 
spectrums of power, audio, and video frequencies. 
Mere substitution of ferrous for nonferrous shielding 
does not improve its efficiency significantly because 
the lack of resistive and magnetic continuity at the
edges prevents the flow of circumferential eddy cur-
rents and increases the magnetic-path reluctance. 
The solution: 
A thin, seamless, ferrous shield around all cores 
(Figure 2) optimizes low-frequency magnetic shielding. 
Covering of this shield with an ultrathin seamless coat 
of highly conductive nonferrous material optimizes 
the efficiency of high-frequency magnetic, electro-
static, and plane-wave shielding. Practical types and 
thicknesses of ferrous and nonferrous materials are 
complementary.
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000394 2020-03-16T18:16:55+00:00Z
How it's done: 
Typically, a flat cable (figures 1 and 2) is shielded 
by a 500-microinch-thick layer of a representative 
80% nickel-iron alloy having an initial permeability 
of about 20,000 and a saturation threshold of about 
7,500 gauss; the layer is coated externally with a 
few microinches of copper. Such materials are es-
sential for useful degrees of attenuation. Lower per-
meabilities require excessive thicknesses or numbers of 
layers, while higher permeabilities are excessively 
strain-sensitive and saturate readily. 
For flat cables, application of the principles de-
scribed and use of such materials enable the design 
of shields that- provide useful degrees of isolation 
from magnetic, electrostatic, and plane-wave fields, 
and magnetic-saturation resistance, throughout the 
generally used magnetic spectrum. Such cables incor-
porate also inherent distributed low-pass filtering in 
the interconnection wiring. 
Notes: 
1. No further documentation is available. Inquiries 
may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B69-10401 
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: R. J. Drechsler of 
Douglas Aircraft Company 
under contract to
Marshall Space Flight Center 
(MFS-1 4524)
rj 
. 
Brief 69-10401	 Category 01


Improved ferrous shielding for flat cables

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server