Electrical connectors – Electromagnetic or electrostatic shield – Shielding individually surrounding or interposed between...
Reexamination Certificate
2000-11-07
2001-10-16
Sircus, Brian (Department: 2839)
Electrical connectors
Electromagnetic or electrostatic shield
Shielding individually surrounding or interposed between...
C439S076200
Reexamination Certificate
active
06302738
ABSTRACT:
The invention relates to a microwave attenuating-connector for equipment housed in an electromagnetically shielded housing. It also relates to assemblies including a housing equipped with such a connector.
BACKGROUND OF THE INVENTION
In much electronic equipment contained in housings and in particular in equipment designed for use on board satellites, it is conventional to use effective electromagnetic shielding to protect equipment or elements of RF equipment (i.e. operating at radio frequency) from potentially harmful electromagnetic signals which are capable of reaching the equipment or its more sensitive elements. It is also conventional to enclose equipment or equipment elements in a closed housing that is made of metal or that is metallized for electromagnetic shielding purposes if said equipment of equipment elements generate or are capable of generating potentially harmful electromagnetic signals which must, where necessary, be channeled in appropriate manner, or even confined as much as possible by shielding inside the housing in which they are produced or transmitted. As is known, there is a risk of electromagnetic leakage, in particular for signals corresponding to short wavelengths, e.g. shorter than 3 cm, whenever a shielded housing needs to include one or more openings, and in particular, at least one opening to enable connections to pass between the outside and the inside of the housing. Suitable shielding must thus be provided where there is the risk of leakage in order to attenuate as much as possible any leakage signals.
Shielding against intervening electromagnetic signals transmitted in the Ku and Ka microwave bands involves, for example, attenuation with a mean value of about 70 dB for conventional RF equipment in order to ensure mutual RF compatibility between the various repeaters of a satellite, for example. For example, attenuation of about 100 dB is necessary for sensitive equipment elements e.g. receivers, channel amplifiers.
As it is generally necessary to power equipment and to control it remotely from outside the housing in which it is housed, a low-frequency LF connector is generally provided for this purposes, mounted on the housing in which the equipment is housed. Such a connector includes, for example, DC power supply terminals for the equipment, and terminals for connecting wires that enable remote control and/or remote sensing signals to be transmitted. The connector closes the opening in the housing through which it penetrates and in which it is fixed more or less effectively. Unfortunately LF connectors usually have only very low effectiveness in terms of attenuation, in particular in the Ka and Ku bands. The attenuation obtained is about 10 dB, for example, whereas attenuation of about 80 dB to 100 dB is necessary.
A known solution to that problem is shown in FIG.
1
. It relates to the conventional circumstance in which a shielded electromagnetic housing
1
is equipped with a connector
2
positioned in an opening made therefor in an outer wall of the housing, and in which the connector
2
selectively connects external electric connection wires LE outside the housing to internal connection wires LI housed inside the housing in order to serve equipment contained within said housing. In that known solution, the housing
1
is organized in such a manner that it includes compartments that are electromagnetically isolated from one another, e.g.
3
and
3
A. This is achieved, for example, by adding an intermediate metal wall
4
with the two compartments on opposite sides of the wall. Radiofrequency feed-through filters
5
carried by the intermediate wall
4
enable connection conductors to pass between equipment elements which are not housed in the same compartment. The component elements of the equipment can thus be distributed in the compartments as a function of the level of protection necessary with regard to electromagnetic disturbances. This is shown in
FIG. 1
in which the RF elements that need particular protection form an assembly
6
housed in compartment
3
A and they are separated from the LF elements which form an assembly
7
and which are housed in compartment
3
.
A main drawback of that known solution is that it makes the mechanical structure of the assembly which forms the equipment and its housing complicated and heavy and it substantially increases its cost, in particular in the case of equipment designed for satellites. Special manual operations are required for mounting and wiring the filters and said operations are particularly costly in the case of the application mentioned above. In addition, because of the presence of the filters, such a solution is not suitable for passing fast digital signals from one compartment to the other.
A second known solution is shown in FIG.
2
. It too is designed to be used when it is necessary to intervene in an assembly in which equipment
8
is housed in a housing
1
′ equipped with a connector
2
′ which is mounted in such a manner that the level of electromagnetic protection obtained is insufficient. That solution is used more particularly in the case of an assembly that has already been made, when it is not desirable or neat possible to modify the assembly satisfactorily in order to achieve the required level of protection. Additional external shielding is envisaged in order to complete the shielding of the connector
2
′. In the conventional embodiment shown, a shielding cover
9
is positioned on the electromagnetically shielded housing
1
′ so as to surround the portion of the connector
2
′ which is outside the housing
1
′ when the connector is in place in the housing. The shielding cover
9
thus surrounds the external connection wires LE over a limited length starting from the connector
2
′ to which they are connected. Over-shielding
10
must thus be provided on the harness constituted by the wires outside the cover
9
. The over-shielding is connected to the cover
9
over 360° about the axis on which the harness penetrates into the cover. A conductive gasket
11
completes the shielding in the region in which the cover
9
bears on the outer wall of the housing
1
′. As known, that solution is difficult to implement and it involves fiddley and lengthy manual operations, in particular for making the over-shielding on the harness. It also leads to an increase in the weight of the harness and is thus detrimental to payload in the case of equipment designed for a satellite.
OBJECTS AND SUMMARY OF THE INVENTION
The invention therefore proposes a connector, having more particularly the function of a microwave attenuator, for connecting equipment housed inside an electromagnetically shielded housing to equipment outside the housing when the housing is provided with an opening in which the connector is designed to be engaged, the connector comprising conductive elements for connecting the pieces of equipment together.
According to a characteristic of the invention, the connector comprises a hollow electrically conductive body consisting of a single piece and filled, over at least a portion of its length, with a microwave-absorbing material in which the connection elements are embedded. It also comprises a plug element on which the connection elements are mounted and by means of which the body of the connector is closed in such a manner as to provide a cavity in which said microwave-absorbing material is contained, the plug element enabling the connection elements to be held in position in the connector.
The invention also provides a housing-and-connector assembly comprising an electromagnetically shielded housing for housing equipment, and a connector for connecting said housed equipment to equipment outside the housing, the connector being a connector of the invention and including, in particular, the above-defined characteristic.
REFERENCES:
patent: 5040994 (1991-08-01), Nakamoto et al.
patent: 33 26 629 A1 (1985-01-01), None
patent: 0 661 776 A3 (1995-07-01), None
patent: 2 680 434 A1 (1993-02-01), None
Alcatel
Prasad Chandrika
Sircus Brian
Sughrue Mion Zinn Macpeak & Seas, PLLC
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