Electromagnetic radiation absorbing resin-added two-layer gypsum panel

Abstract

This invention relates to an electromagnetic (EM) radiation absorbing two-layer gypsum panel effective in the 8.2-12.4 GHz frequency range, obtained by adding carbon black and magnetite in specific ratios to resin-added gypsum in each layer.

Description

[0001] ELECTROMAGNETIC RADIATION ABSORBING RESIN-ADDED TWO-LAYER GYPSUM PANEL

[0002] Technical Field

[0003] This invention relates to an electromagnetic (EM) radiation absorbing resin-added two-layer gypsum panel.

[0004] Prior Art

[0005] In document No. CN106476357A, a panel for electromagnetic shielding purposes is disclosed. Said panel comprises one or more amorphous alloy layers within a gypsum matrix. The amorphous alloy layers have an epoxy coating serving a protective function. It is stated that, in order to ensure effective shielding, certain properties of the amorphous alloy layer can be determined in a manner to provide a selective shielding effect for different frequency bands, and that tests and simulations can be utilized for this purpose.

[0006] In document No. CN115195224A, a fire-resistant sound insulation panel is disclosed. In the panel, epoxy is used in a distributed form within a gypsum matrix.

[0007] In document No. US2020031718A1, a construction mortar for electromagnetic shielding purposes is disclosed. It is stated that the mortar may be a mixture comprising various materials, including gypsum and epoxy. It is stated that electromagnetic radiation absorbing glass spheres are used in the mortar and that these may have conductive coatings including magnetite and carbon.

[0008] In document No. JP2019099690 A, a panel comprising an elastic layer and a coating is disclosed. It is also stated that this coating may be epoxy. It is also stated that the elastic layer and the coating may contain a material providing an additional function. Gypsum is also included among these materials providing an additional function. Furthermore, it is mentioned that among the materials providing an additional function, there may be carbon black and magnetite with electromagnetic radiation absorbing properties, as well as boron nitride providing thermal conductivity.In the document titled “ABC algorithm-based optimization and evaluation of nano carbon black added multi-layer microwave absorbing ultra weight foam concrete” (Yildizel, S. A., & Toktas, A. (2022). Materials Today Communications, 32, 104035.), referenced in the invention disclosure and co-authored by the inventors, a four-layer microwave absorbing panel and the design thereof are disclosed. Foam material was used in the layers to ensure broadband absorption.

[0009] The control of EM waves has gained importance in areas such as the concealment of strategic military buildings from radar systems, and in laboratories and special rooms of buildings where sensitive electromagnetic measurements are performed. Electromagnetic Radiation Absorbing (EMRA) structures are used for the absorption of EM waves by being incorporated into surface coatings, functional materials, and inner layers.

[0010] Objectives and Brief Description of the Invention

[0011] The object of this invention is to develop a panel exhibiting electromagnetic radiation absorbing behavior over a wide frequency range and a method for the design of this panel.

[0012] According to the invention, a panel consists of epoxy resin-added gypsum layers loaded with carbon black and magnetite. Thanks to its multi-layer structure, the absorption of a wide frequency range can be achieved by dividing the frequency range intended to be absorbed into sub-ranges, with a series of layers each corresponding to a sub-range.

[0013] The layer thicknesses and electrical properties (or the composition corresponding to these properties) constituting the multi-layer panel subject of the invention are designed by optimization. The design parameters of Multi-layer EMRA structures, formed by the combination of two layers having different thicknesses and electrical properties suitable for broadband applications, are determined by the optimization of objectives such as reflection and thickness.

[0014] Detailed Description of the Invention

[0015] The panel developed to achieve the objectives of this invention is illustrated in the attached figures.

[0016] Figure 1 A schematic side cross-sectional view of a panel according to the invention.Figure 2 The reflection coefficient graph of the panel according to the invention.

[0017] The parts in the figures are numbered individually and the counterparts of these numbers are given below.

[0018] 1. First layer

[0019] 2. Second layer

[0020] G. Incident wave

[0021] Y. Reflected wave

[0022] A method for designing an electromagnetic radiation absorbing panel, it fundamentally comprises;

[0023] creating a material pool by adding various carbon black and magnetite materials to a gypsum / cement / resin mixture in specific ratios,

[0024] determining electrical properties by performing EM characterizations of the obtained material samples,

[0025] performing multi-layer designs to achieve the minimum reflection loss by optimizing the obtained electrical properties via an optimization algorithm,

[0026] producing the number of layers and the material sample to be used in each layer belonging to the panel that yields the minimum reflection coefficient values with the minimum number of layers,

[0027] producing target values lower than -10 dB in the panel subject to the patent, manufacturing the produced panel and performing measurements thereof.

[0028] The generated output may consist of a human-readable output intended for a user, a machine-readable output intended for a production tool in the form of work instructions regarding production stages corresponding to each layer in a sequential manner, or a combination thereof.

[0029] The panel according to the invention fundamentally consists of two layers, namely a first layer (1) located on the shielded environment side and a second layer (2) located on the electromagnetic radiation source side, each comprising at least one matrix material, at least one ferromagnetic additive in powder form, and at least one conductive additive in powder form. Preferably, a gypsum / resin mixture is selected as the matrix material, magnetite (FeaCU) as the ferromagnetic additive, and carbon black as the conductive additive.The total thickness of the panel according to the invention, which is effective in the 8.2-12.4 GHz frequency range, is in the range of 9-10 mm. In a preferred embodiment of the invention, the first layer (1) has a thickness of 3.4-3.6 mm and comprises 1% carbon black and 5% magnetite by weight. In this embodiment, the second layer (2) has a thickness of 5.4-5.6 mm and comprises 7.5% carbon black and 20% magnetite by weight.

[0030] A portion of an incident wave (G) reaching the panel from at least one electromagnetic radiation source located on the second layer (2) side of the panel reflects (Y) from the air-first layer interface, the remainder of the wave reflects from the first layer (1) - second layer (2) interface, and the other remainder arrives at the subsequent air interface through the second layer (2), and at this interface, a portion of the incident wave reflects while the remaining portion continues and is transmitted to the other side. In this way, the reflected waves are absorbed within the layers of the material by reflecting iteratively. With this mechanism within the layered structure, the shielding property of the material is provided in an enhanced state.

[0031] According to an exemplary embodiment of the invention, a Multi-layer EMRA epoxy / gypsum panel has been designed and manufactured for use in buildings for the X-band (8.2-12.4 GHz) frequency range. Epoxy-gypsum material samples were produced by adding carbon black and magnetite powders in specific ratios to the base mixture in order to differentiate the electrical properties of the material to be used in the layers and to impart absorption capability to the material. The electrical properties of the produced epoxy / gypsum material samples were measured using EM characterization methods, and a material pool was created for the optimization process via an optimization algorithm. Subsequently, panels with layers ranging from 1 to 5 layers were designed using the optimization algorithm within the framework of the objectives. A two-layer design with a thickness of 9.06 mm, meeting the objectives in terms of return loss performance and layer count balance, was realized, and scattering parameter measurements were performed. The radiation absorbing property of the panel in the 8.2-12.4 GHz range was confirmed by the performed simulations and measurements. The reflection coefficient graph showing the measurement results is also presented in Figure 2.

[0032] The Multi-layer EMRA panels obtained according to the invention have a wide range of applications as they possess high radiation absorbing properties along with EM shielding. These panels are suitable for use in military, security, EM measurement rooms, andhealthcare fields. The panel can be easily applied to desired locations in buildings to ensure the invisibility of military and strategic buildings against radar systems, to protect people and systems from EM emitting devices, and to create EM Anechoic chamber environments.

Claims

CLAIMS1. A two-layered electromagnetic radiation absorbing gypsum panel effective in the 8.2-12.4 GHz frequency range, wherein each layer of the panel comprises a gypsum / resin mixture, carbon black, and magnetite, characterized in that the first layer (1) has a thickness of 3.4-3.6 mm and comprises 1% carbon black and 5% magnetite by weight.

2. The electromagnetic radiation absorbing gypsum panel according to claim 1, characterized in that the second layer (2) has a thickness of 5.4-5.6 mm and comprises 7.5% carbon black and 20% magnetite by weight.

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