Electromagnetic interference shielded enclosures made of composite material having perfect magnetic conductor surfaces

Abstract

The invention relates to a composite enclosure having perfect magnetic conductor surfaces enabling the mechanical shielding of microwave systems used particularly in satellite, space, aerospace, and communication systems, as well as in other high-frequency applications, from electromagnetic interference.

Description

[0001] DESCRIPTION

[0002] ELECTROMAGNETIC INTERFERENCE SHIELDED ENCLOSURES MADE OF COMPOSITE MATERIAL HAVING PERFECT MAGNETIC CONDUCTOR SURFACES

[0003] Technical Field

[0004] The invention relates to a composite enclosure having perfect magnetic conductor surfaces enabling the mechanical shielding of microwave systems used in other high frequency applications, especially satellite, space, aviation, and communication systems, from electromagnetic interference.

[0005] Prior Art

[0006] Metal enclosures made of aluminum or copper and exhibiting Faraday cage property are widely used in many sectors, especially satellite, space, aviation, and communication, for the protection of microwave systems from electromagnetic interference. However, the high specific weight of metals limit the uses of metal enclosures. Composite materials have started to be used instead of metals nowadays as an alternative to metals due to the mechanical (strength, toughness, etc.) and / or physical (electrical conductivity, thermal conductivity, etc.) properties they provide. Furthermore, although microwave systems are isolated from the external magnetic field when they are positioned inside metal enclosures, they are exposed to electromagnetic interference due to cavity resonances formed inside the metal enclosure. For the suppression of this interference, the positioning of pins made of conductive material into the metal enclosures used is required. While the positioning of the pins suppresses the unwanted cavity resonances inside the enclosure by exhibiting a perfect magnetic surface effect, it also increases the weight of the metal enclosure.

[0007] The document titled 'Electromagnetic interference shielding materials: recent progress, structure design, and future perspective', discloses electromagnetic interference shielding materials: recent progress, structure design, and future perspective. The rapid development of electronic equipment and the sharp increase in the demand for wireless communication have led to a significant increase in electromagnetic pollution. As a result, electromagnetic interference (EMI) shielding materials have been developed with the aim of solving the serious problem of electromagnetic pollution. However, 5G communication technology and modern electronic products demand shielding materials having higher requirements in terms of EMI shielding performance, weight, flexibility, and reliability. This review focuses on recent research developments on the structural design, characterization, and properties of various EMI shielding materials, including metal type, carbon type, and MXene type. The basic theory of EMI shielding has been introduced in detail, and existing test technologies for EMI shielding effectiveness have been summarized. This may help the understanding of structural design principles for shielding materials. The effect of different carbon materials classified as zero-dimensional, one-dimensional, two-dimensional, and three-dimensional on shielding performance and the corresponding shielding mechanism have been discussed. Furthermore, near-field shielding and its applications in the field of electronic packaging have been introduced. Based on our comprehensive analysis, the main challenges and prospects encountered by EMI shielding materials in future research have been presented.

[0008] The document numbered KR101337959B1, discloses an electromagnetic wave shielded composite. This invention relates to an electromagnetic shielding composite and is specifically directed to an electromagnetic shielding composite capable of shielding electromagnetic waves generated by electronic components effectively.

[0009] The document numbered KR20230072951 A, discloses a plastic composite material for EMI shielding. This invention relates to a plastic composite material for electromagnetic wave shielding. According to an embodiment of the invention, the plastic composite material for electromagnetic wave shielding may consist of the following components: a plastic base and an aluminum sheet placed on the plastic base. According to an embodiment of this invention, the plastic composite material for electromagnetic wave shielding may be used in a vehicle battery housing. Therefore, the invention makes it possible to provide shielding against radiated electromagnetic waves effectively.

[0010] The document numbered CN212519857U, discloses a combined formula spliced modular carbon fiber composite shielding chassis. This utility model belongs to the technical field of the spliced box body and specifically relates to a combined formula modularized carbon fiber composite shielding chassis.

[0011] The document numbered JP6225436B2, discloses an electromagnetic wave shielding film and a method for coating electronic components. This invention relates to an electromagnetic wave shielding film used to cover the irregularities of a substrate and an electronic component coating method.

[0012] When the studies existing in the prior art are examined, the need for the development of the composite enclosure subject to the invention, having perfect magnetic conductor surfaces and enabling the mechanical shielding of microwave systems used particularly in satellite, space, aerospace, and communication systems, as well as in other high-frequency applications, has been felt.

[0013] Objectives of the Invention

[0014] The object of this invention is to develop a composite enclosure having perfect magnetic conductor surfaces enabling the mechanical shielding of microwave systems used particularly in satellite, space, aerospace, and communication systems, as well as in other high-frequency applications, from electromagnetic interference.

[0015] Another object of this invention is to develop a composite enclosure enabling the suppression of cavity resonances that will occur inside the enclosure throughout the operating frequency range thanks to carbon rods to be positioned inside the enclosure.

[0016] Another object of this invention is to develop a composite enclosure endowed with structural properties such as high strength, high elasticity, and a good degree of fatigue and creep, etc. Detailed Description of the Invention

[0017] The composite enclosure developed to achieve the object of this invention is shown in the attached figures.

[0018] These figures;

[0019] Figure 1: A schematic view of the composite enclosure subject to the invention.

[0020] Figure 2: A schematic view of the cover of the composite enclosure subject to the invention.

[0021] Figure 3: A schematic top view of the composite enclosure body subject to the invention.

[0022] Figure 4: A schematic side view of the cover of the composite enclosure subject to the invention.

[0023] Figure 5: A schematic view of the cover in an alternative design of the composite enclosure subject to the invention.

[0024] The parts located in the figures have been numbered individually, and the equivalents of these numbers are given below.

[0025] 1. Enclosure body

[0026] 2. Cover

[0027] 3. Rods

[0028] A composite enclosure having perfect magnetic conductor surfaces enabling the mechanical shielding of microwave systems used particularly in satellite, space, aerospace, and communication systems, as well as in other high-frequency applications, from electromagnetic interference, and comprises;

[0029] An enclosure body (1) manufactured from composite material, whose inner and outer surfaces are coated with polypropylene, aramid, para-aramid, or glass fibers, A cover (2) to be closed onto the enclosure body (1), Carbon rods (3) positioned on the lower surface of the cover (2) in a manner to enter into the enclosure body (1) and having gaps between them.

[0030] For the production of the carbon rods (3) located in the composite enclosure subject to the invention, engineering plastics such as polyethylene (PE), polypropylene (PP), acrylonitrile butadiene styrene (ABS) resins, polycarbonate (PC), polyamide (PA), polyetheretherketone (PEEK), polyetherimide (PEI), polyphenylene sulfide (PPS), and polyethersulfone (PES) are preferred as matrix material. The carbon nanotube filled composite material is firstly homogeneously mixed with the thermoplastic matrix materials given above via twin-screw extrusion and is made into composite granules containing carbon nanotube filler at a rate of 0.1-10%. Subsequently, using the nanocomposite granules, rods (3) with cylindrical crosssection are produced using one of the ram extrusion, screw extrusion, or injection molding methods.

[0031] Additionally, these rods (3) can also be produced using thermoset matrices such as epoxy, orthophthalic polyester resin, terephthalic polyester resin, chlorendic acid polyester resin, novolac epoxy vinyl ester resin, isophthalic polyester resin, bisphenol-A fumarate polyester resin, bisphenol-A vinyl ester resin, phenolic resins, polyurethane, and polyurea. In this case, firstly, carbon nanotubes are mixed in a homogeneous manner using a mechanical and ultrasonic mixer with the matrix material in a cooled environment. Subsequently, after mixing is performed again with the cross-linking material and the gas is removed by being kept under vacuum, it is poured into two-part metal molds with cylindrical or square cross-section, and then the composite material is cured and solidified by heating the molds.

[0032] In addition to this, the rods (3) can also be produced using elastomer matrix materials such as styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), and chloroprene rubber (CR). The carbon nanotubes added to the rubber compound are mixed with other additive materials in Banbury and then in open mill mixers. Subsequently, the composite material in the form of dough is produced as a rod (3) with cylindrical or square cross-section via the extrusion process. The cross-linking agent ratio used in rubber materials is around 15-20%, and in this way, it is ensured that the produced rods (3), after being cured and their cross-links are formed, are not elastic but hard rubber-based nano-filled electrically conductive composites. The rods (3) will be positioned on the cover (2) of the enclosure by injection molding, and in those produced by extrusion, by means of opening a thread with a lathe subsequently.

[0033] In the composite enclosure subject to the invention, the use of conductive carbon rods (3) instead of aluminum or copper rods for the suppression of unwanted EM resonances, and the production of the body (1) parts of the enclosures from composite material having conductive properties, and the coating of their surfaces with polypropylene, aramid, para-aramid, and glass fibers are aimed. In this way, both the reduction of the weights of the enclosures containing PMC surfaces and the imparting of structural advantages such as high strength, elasticity, fatigue and creep resistance to the enclosure are aimed. The type of the composite material used is not important, and any composite material providing the desired electrical and mechanical properties in designs and productions can be used. On surfaces where insulation is desired, glass fiber, basalt fiber, aramid, and para-aramid continuous and discontinuous fibers will be used as reinforcement material. On surfaces where electrical conductivity is desired, continuous and discontinuous carbon fiber reinforcements will be used.

[0034] Furthermore, by using carbon rods (3) having different lengths and widths together, the operating frequency bandwidth of the enclosure will be increased, or it will be ensured that it exhibits a multi-band characteristic.

[0035] The modules (rooms) located in the inner part of the composite enclosure subject to the invention are used for the electromagnetic isolation of the microwave systems from each other. Therefore, the number of modules (number of rooms) and size will show variation depending on the number of microwave systems to be used in the designs and the operating frequency values.

[0036] Thanks to the composite enclosure subject to the invention, all or subsystems of the microwave systems used in high frequency applications will be able to work in an efficient manner without being affected by the electromagnetic interference found in the environment. Furthermore, thanks to the carbon rods (3) to be positioned inside the enclosure, the proposed design will enable the suppression of the cavity resonances that will occur inside the enclosure throughout the operating frequency range. By coating the surfaces of the composite materials with different polypropylene, aramid, para-aramid, and glass fibers, the enclosures will both possess high physical and mechanical properties, and the outer surfaces will exhibit insulation property in the electrical sense. The use of composite materials in the enclosure will impart structural properties such as high strength, high elasticity, a good degree of fatigue and creep, etc.

Claims

CLAIMS1. A composite enclosure having perfect magnetic conductor surfaces enabling the mechanical shielding of microwave systems used particularly in satellite, space, aerospace, and communication systems, as well as in other high-frequency applications, from electromagnetic interference, characterized in that it comprises: an enclosure body (1) manufactured from composite material, whose inner and outer surfaces are coated with polypropylene, aramid, para-aramid, or glass fibers, a cover (2) to be closed onto the enclosure body (1), carbon rods (3) positioned on the lower surface of the cover (2) in a manner to enter into the enclosure body (1) and having gaps between them.

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