RU128790U1 - PROTECTIVE SCREEN TO REDUCE THE LEVEL OF MICROWAVE RADIATION OF CELL PHONES - Google Patents

Abstract

1. A protective screen to reduce the microwave radiation of a cell phone made of parallel layers of materials, including an electromagnetic wave absorber, an electromagnetic wave reflector and a protective and decorative coating, characterized in that the absorber is made of a material based on a binder containing a mixture of microwave ferrite powder and carbon nanostructures with a mass ratio of approximately 9: 1 in a total amount of 48 ÷ 52 wt.%, and the reflector is made of non-metallic material based on a binder, soda zhaschego carbon nanostructure in an amount of 10 ÷ 15 wt.%. 2. The protective screen according to claim 1, characterized in that a powder of hexaferrite with a particle size of 1 ÷ 5 μm is used as a powder of microwave ferrites. The protective screen according to claim 1, characterized in that the polymers are used as binders, for example polymethyl methacrylate, silicone or epoxy resin.

Description

The utility model relates to the field of environmental protection and human ecology, and more specifically to systems for protecting a person from high-frequency electromagnetic radiation. The device can be used to protect the human body from the harmful effects of electromagnetic radiation from a mobile phone, as well as household, industrial and scientific equipment operating in the high-frequency field of radiation.

State of the art

Today, there are a number of different devices designed to protect against the harmful effects of cell phone radiation on the human body.

Among them, very peculiar solutions can be noted. These include the use of a grounded swordsman mask (Pat. RF No. 2381042, 2010) or a cap made using materials that shield the head from electromagnetic radiation (US 2005/0108811 A1, 2005) by placing them on the head of a speaker using a cell phone. Although these solutions provide a high level of radiation protection during conversations, their drawbacks are obvious. They are inconvenient to use, the speaker’s mobility is reduced, they protect only the person’s head and do not help if the phone is located near other parts of the body.

Known devices designed to protect the human body from high-frequency exposure to the radiating elements of cell phones.

US Pat. No. 6,711,387 uses cases for a mobile phone in which the elements located between the antenna of the cell phone and the human head are made of shielding materials.

The disadvantages of this type of device are cumbersome, overweight, inconvenience to use and poor communications in cases of a small number of nearby base stations.

In cell phones with protective devices according to US patents 5336896, 5940039, in addition to the phone protective cover, it is proposed to use a special antenna design to shift the radiation and reception of the cell phone signal away from the user's head and to avoid communication deterioration.

The main disadvantages of this type of device are the poor ergonomics and inconvenience of using the presented antenna design, which is crucial in the trends in the modern development of electronics, tending to miniaturization and mobility. Also, such an antenna design can be dangerous for people nearby.

The development described in US Pat. No. 5,367,309 is a protective shield covering the antenna of the mobile phone on the head side.

The disadvantages of such devices is a noticeable decrease in the quality of communication, which leads to an increase in the power consumed by the cell phone required to maintain the required signal level. As a result, the device’s battery life and user mobility are significantly reduced.

Known designs (US 5787340) for protection against radiation of a mobile phone in the form of an additional screen attached to a cell phone between the antenna and the human head.

The disadvantages of the known devices are the design complexity of the screen mount. Such devices operate only during a conversation and in no way protect a person when the phone is in standby mode. This increases the weight and decreases the mobility of the device. In addition, such types of devices are not applicable to all classes of modern cell phones, and in some cases worsen the quality of communication.

Known devices for protecting the human body from high-frequency electromagnetic radiation of a mobile phone, consisting of elements of a cell phone housing facing the human body, made of metallized materials (US 5150282) and materials containing ferromagnetic powders (RU 2237376).

The disadvantages of the first type of devices is the influence of the housing elements on the transmitting and receiving characteristics of a cell phone due to the re-reflection of radiation from the shielding surfaces. In some cases, the corners of the screens can serve as amplifying antennas, increasing the irradiation of individual parts of the human body or lead to interruptions in communication with a small number of cell towers, because the signal can be shielded depending on the location of the phone.

The disadvantages of the second type of devices is the effect of elements containing ferromagnetic powder on the operation of the transmitter and receiver of the mobile phone due to their close proximity to the telephone antenna. In this case, the signal level is weakened and the quality of communication is deteriorated, which leads to a faster discharge of batteries. The use of such devices is possible only in those models where the use of ferromagnetic powder is provided for by the manufacturing technology of the cases.

The closest in technical essence to the claimed development is a protective screen according to US Pat. No. 76505 U1, containing an electromagnetic wave absorber, a reflective substrate (metal base of the screen) and a thin layer of protective and decorative coating. The absorber layer is made of a rubber mixture filled with carbonyl iron powder, processed in fine wet grinding attritors to an average particle size of 0.5 ÷ 3.0 μm, with a carbonyl iron content of up to 80 wt.%

A disadvantage of the known device is: a significant thickness of the screen and the uncertainty of the composition of the rubber compound, the properties of which depend on the processing regime of iron in the attritors. The protection efficiency in the long-wave range of radio frequencies (850 ÷ 950 MHz) is low. The durability of the connection of the metal foil and the rubber compound is doubtful. When the iron content is about 80 wt.%, The fragility of the material increases, its flexibility and mechanical strength decrease. Carbonyl iron and other metals have a higher density than traditional ferrite compounds, which negatively affects the mass of the protective shield.

The creation of this utility model is based on the task of obtaining a protective screen that provides enhanced protective properties without the use of metal elements in the design.

The problem is solved as follows.

The protective screen to reduce the microwave radiation level of cell phones is a thin flat multilayer plate including an electromagnetic wave absorber, an electromagnetic wave reflector and an external protective and decorative coating.

The absorber is made of a composite material based on a binder, which contains a mixture of fine powders of microwave ferrites and carbon nanostructures in a mass ratio of about 9: 1. The mass amount of filler (mixture of powders) is about half the mass of the composite material. A non-metallic material based on a binder containing 10–15 wt% carbon nanostructures was used as a reflective layer. The layers are glued with an adhesive. The total thickness of the layers is 2.5 mm or less, the layers are selected in such a way that the reflection of radiation from the screen does not exceed 12% in the frequency range 1.8 ÷ 1.9 GHz and does not exceed 8% in the frequency range 850 ÷ 950 MHz. As a powder of microwave ferrites, hexaferrite powder with a particle size of 1 ÷ 5 μm can be used. As a binder, polymeric substances can be used, for example, polymethyl methacrylate, polymer paint, silicone, epoxy resin, rubber, depending on the operating conditions of the protective screen,

The proposal is illustrated by diagrams.

Figure 1 shows a diagram illustrating the use of the device.

Figure 2 shows a diagram of a possible design of the device.

The numbers indicate: 1 - a protective screen; 2 - case; 3 - a radiating device, for example, a mobile phone; 4 - matching layer, based on a binder, for example, a polymer composite (48-52 wt.%), With microwave ferrites (44-46 wt.%) And carbon nanostructures (4-6 wt.%) ,; 5 - non-metallic layer based on a binder with a high concentration of carbon nanostructures (10-15%), actively interacting with radiation; 6 - external decorative coating of a thin film or fabric.

The device operates as follows.

A protective screen is located between the phone and the human body. At the same time, a thin non-metallic layer is located closer to the human body, and a thicker matching layer is closer to a cell phone. The main attenuation of radiation in the composite material is provided by a combination of conductive nanocarbon structures and microwave ferrites, for example, ultrafine hexaferrite powder, interacting with electromagnetic fields of the microwave range. The choice of the concentration of the components of the active phase of the first layer ensures coordination with free space and a decrease in the total level of reflected radiation from the second layer. Moreover, at frequencies from 100 MHz to 2 GHz, attenuation occurs mainly due to absorption, and at higher frequencies, the reflection scattering electromagnetic radiation into the surrounding space also affects. Moreover, the density of carbon nanostructures is significantly lower than that of carbonyl iron, as in the prototype, or of other metals, thereby achieving a reduction in the weight characteristics of the device.

The protective screen 1 (figure 1) to reduce the microwave radiation level of cell phones is located in a clothing pocket or in a case 2, between the mobile phone 3 and the human body. Layer 4 with a thickness of approximately 2 mm, consisting of a composite material based on ultrafine powders of microwave ferrites, carbon nanostructures and a polymer binder (Fig. 2), is bonded with an adhesive with a thin non-metallic layer 5, which actively interacts with electromagnetic radiation. Layer 5 consists of a composite with the addition of carbon nanostructures. The coordination of the reflecting and absorbing properties of the layers is achieved by selecting the thickness of the layers. Together, both layers of the material form the active region of the protective shield, the reflection coefficient from which is 0.08-0.12 at the cellular frequencies (850 ÷ 950 MHz and 1.8 ÷ 1.9 GHz). This allows us to exclude the influence on the screened object of waves and resonance phenomena reflected from the screen, therefore, the transmitting and receiving characteristics of a mobile phone remain unchanged. The outer surface of the screen is covered with a thin decorative film or fabric 6 (figure 2), which protects the active layers from external influences and improves the appearance.

An example implementation. The protective screen is a thin flat plate consisting of several layers. The main attenuation of radiation in the protective shield is provided by a non-metallic layer 5 of a thickness of 0.4 mm containing carbon nanostructures in an amount of 10-15 wt.% (Figure 2), since such a composite material is characterized by high values of the reflection and absorption coefficients of the radiation. Layer 4 with a thickness of 2 mm is made on the basis of a binding agent (50 wt.%), Into which a mixture of ultrafine hexaferrite powder (45 wt.%) And carbon nanostructures (5 wt.%) Is introduced. Layer 4 provides coordination and reduction of the overall level of reflected radiation. This allows us to exclude the influence of reflected waves from the screen and resonance phenomena, which can lead to a sharp increase in the radiation power, firstly, adversely affecting the human body, and secondly, affecting the characteristics of the receiving and transmitting elements of a mobile phone. Polymethylmethacrylate was used as a binder. The density of the microwave microwave carbon nanostructures used is lower than that of carbonyl iron or other metals, which leads to a lower mass of the declared protective shield in comparison with the prototype with the same dimensional parameters. Microwave ferrite powder with a particle size of 1 ÷ 5 μm can be used in the device, which is significantly cheaper than carbonyl iron powder pretreated in attritors with an average particle size of 0.5 ÷ 3.0 μm.

A protective screen to reduce the microwave radiation level of cell phones can be used as an insert in your pocket or in a case for a cell phone. The screen allows you to significantly reduce the level of electromagnetic radiation passing through it at cellular frequencies.

The reflection and transmission coefficients of the electromagnetic radiation of the protective shield were measured using the waveguide method using a coaxial measuring cell. The experimentally obtained results are shown in the table.

Table. Basic electrophysical characteristics of the protective screen Parameter Name Value The transmission coefficient T at a frequency f T% 400 MHz 61.7 900 MHz 50.7 1800 MHz 44.6 2400 MHz 35,4 3500 MHz 28.7 Reflection coefficient R at frequency f R% 400 MHz 3.8 900 MHz 8.0 1800 MHz 10.6 2400 MHz 21.1 3500 MHz 25.1 Absorption coefficient A at a frequency f A% 400 MHz 34.5 900 MHz 41.3 1800 MHz 44.8 2400 MHz 43.5 3500 MHz 46.2

The table shows that the transmission coefficient T decreases with frequency. In this case, the absorption coefficient A remains almost unchanged, and the reflection coefficient R increases. The reflection of radiation from the screen is less than 12% (prototype 5%) in the frequency range 1.8 ÷ 1.9 GHz and no more than 8% in the frequency range 850 ÷ 950 MHz (prototype 35%, which may affect the quality of communication) with a total screen thickness of d = 2.5 mm (for the prototype d> 2.5 mm). The attenuation of radiation by a protective screen in the used frequency range is 50 ÷ 65% (for the prototype 20 ÷ 80%).

The device is effective in the search modes of the base station, standby, call, as well as conversation using a headset.

The technical result is to reduce the mass of the screen and reduce the level of microwave radiation of cell phones without the use of metal elements in the design.

Claims (3)

1. A protective screen to reduce the microwave radiation of a cell phone made of parallel layers of materials, including an electromagnetic wave absorber, an electromagnetic wave reflector and a protective and decorative coating, characterized in that the absorber is made of a material based on a binder containing a mixture of microwave ferrite powder and carbon nanostructures with a mass ratio of approximately 9: 1 in a total amount of 48 ÷ 52 wt.%, and the reflector is made of non-metallic material based on a binder, soda zhaschego carbon nanostructure in an amount of 10 ÷ 15 wt.%. 2. The protective screen according to claim 1, characterized in that a powder of hexaferrite with a particle size of 1 ÷ 5 μm is used as a microwave ferrite powder. 3. The protective screen according to claim 1, characterized in that the polymers are used as binders, for example polymethyl methacrylate, silicone or epoxy.

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