FOR INDUSTRIAL APPLICATIONS OF VARIOUS KIND, AND IN PARTICULAR

ELECTROMAGNETIC WAVES ABSORBING TILES”

The invention relates to shielding devices for the electromagnetic waves, which are utilized for industrial applications of various kind, and in particular electromagnetic waves absorbing tiles.

It is known the fact that in the terrestrial environment in which the persons live there are produced electromagnetic fields of natural origin, and that such natural electromagnetic fields combined also with electromagnetic fields of artificial origin, that are produced by the scientific and technological development, for making available applications of various kind that are requested by the persons and make more comfortable and pleasant the quality of life of the same persons.

For example, the artificial electromagnetic fields may be produced by electrodes of electrical plants of various kind, by the telecommunications plants, by the mobile phones, by the electromagnetic fields produced inside the domestic and working environments, as the ones generated by electrical devices and appliances, by electrical machines, by treating machines with electro waves for products of various kind.

Between the main artificial sources of electromagnetic fields in the environment we must include : Low frequency electromagnetic fields (0 Hz - 10 KHz) generated by apparatuses for the transport and the delivery of electric energy or by electrodes. These electromagnetic fields are generated by very high, high, medium and low voltage lines, by generating stations and by transforming stations and rooms of the electric energy ;

High frequency electromagnetic fields (10 KHz - 300 GHz) generated by plants for radio telecommunications, comprising radio and television broadcasting systems, link plants for radio, television and for mobile phone and landline (radio link) and the radars.

Two groups of electromagnetic waves interact in different ways with the living bodies and cause different risks for the human health : the high frequency (RF) electromagnetic fields yield energy to the human tissues in the form of heating, and the low frequency electromagnetic fields (ELF) induce electric current in the human body.

Referring to the ELF, the international regulations provides for the respect of strict reference thresholds of the electromagnetic fields in presence of electrodes, as for example the portions of territory around the line which encircles the territory in which it is not allowed to stop and/or to live inside inhabited buildings for long periods.

Instead, as far the RF are concerned, by means of international regulations, limits for the exposition of the human body to high intensity electromagnetic fields for short durations have been established, in a way to limit the constant increasing of the body temperature below of 1°C, in order to produce variations of body temperature lower than the ones associated to the normal physiological processes and so well acceptable by the organisms also for promulgated times, and this is for protecting the persons from possible acute effects that may damage the same organisms.

Now, there are not available particular precautions for avoiding the propagation of these latter electromagnetic fields in the environment, but currently there are effected controls and detections of the sources of these electromagnetic fields, for verifying that such sources don’t exceed determined levels of the generated electromagnetic fields. However, it is not always possible to detect with confidence that the values of the electromagnetic radiations present in the environments are lower to the maximum limits established by the regulations, and that consequently the persons who may stay in these environments are not exposed to the risks for their health.

Actually, it is known the fact to use electrical or microwave apparatuses for different applications, which are built with adequate shields against the electromagnetic fields generated by the same apparatuses, for limiting and reducing or for eliminating the intensity of the emitted electromagnetic radiations, with consequent small damages or elimination of the damages to the human organism who come in contact with the same radiations.

In the case of industrial microwave apparatuses for different applications, the shielding of the same electromagnetic radiations is difficult at the moment, because of such a shielding is effected with metallic materials used for the building of the same apparatuses, and in these metallic materials the microwaves are conveyed and don’t propagate outside the same ones, and for ensuring efficient protections, the microwave apparatuses are made with wide surfaces made of metallic materials, circumstance that if on one the one hand increase the shielding effect against the microwaves, on the other hand increase the constructive sizes of these apparatuses, and so it requires the use of a great quantity of material and of working phases of this latter. However, the shielding of the metal sheet against the microwaves can’t be used for shielding rooms and/or paved surfaces against electromagnetic waves generated by electrical plants included in these environments, that produce overheating of metals and the phenomenon of reflection of the waves that may produce opposed effects to the shielding and that consequently are not absolutely adapted to be used in these applications.

The object of the present invention is to realize suitable shielding device for the electromagnetic waves for applications of various kind above specified, and particularly to realize absorbing tiles for electromagnetic waves, adapted to perform the function to absorb efficiently the electromagnetic waves emitted by microwaves apparatuses and the ones emitted by electrical plants included in rooms and/or paved surfaces, wherein such shielding devices don’t have the problems and the limits of the shielding devices used actually. The shielding devices and in particular the absorbing tiles of electromagnetic waves according to the present invention are realized with the constructive characteristics substantially will be described below, by way of a not-limitative example and with reference to the accompanying drawings in which :

Fig. 1 shows a front perspective view of an absorbing tile of electromagnetic waves for applications of various kind, without surface coating ;

Fig. 2 shows a front perspective view of an absorbing tile of electromagnetic waves for applications of various kind, with surface coating of white cement ;

Fig. 3 shows a front perspective view of an absorbing tile of Fig. 1, sectioned in the longitudinal direction thereof, at the middle of its width ;

Fig. 4 shows front perspective view of an absorbing tile of Fig. 2, sectioned in the longitudinal direction thereof, at the middle of its width ;

Fig. 5 shows a front view of a little raceway for containing electrical wires, with an upper closing lid, made of the same constructive material of an absorbing tile of electromagnetic waves, according to the invention ;

Fig. 6 shows front perspective view of an absorbing tile according to the invention, whose constructive material has been poured on a set of electrical wires ;

Fig. 7 shows a front perspective view a an arrangement of various absorbing tiles joined to each other, without surface coating ;

Fig. 8 shows a front perspective view a an arrangement of various absorbing tiles joined to each other, with a surface coating of white cement ;

Fig. 9 shows a front perspective view of a raceway for containing electrical wires, with an upper closing lid, as the one of Fig. 5, with e determine length ;

Fig. 10 shoes a front perspective view a an arrangement of various absorbing tiles joined to each other, according to the invention, in whose material there are embedded various electrical wires ;

Fig. 11 shows a front perspective view of a tunnel-shaped apparatus for treating by microwaves products of various kind, provided with shielding tiles against electromagnetic waves according to the invention.

The present invention refers to shielding devices for electromagnetic waves, used in industrial applications of various kind, and in particular to absorbing tiles of electromagnetic waves that is electromagnetic fields. The absorbing tiles of electromagnetic fields are made with particular compound of materials of various kind, that will be described in detail after and, depending on the materials that are used, they are able to absorb the energy of the electromagnetic radiations with different wavelengths.

These absorbing tiles are described by referring to figs. 1-11 and may be advantageously used for covering walls of rooms and/or paved surfaces, for shielding the same against the electromagnetic radiations generate by electrical plants included in these environments or electromagnetic fields generated by external telecommunication plants. These types of absorbing tiles, furthermore, may be used specially for these applications :

For covering electric rooms ;

For covering industrial microwave ovens ;

For covering paving in houses wherein there is not desired to be exposed to electromagnetic waves generated by plants installed in the same rooms or generated by external plants, as for example for the functioning of the radio telecommunications ;

For covering other staying places in which the persons must stay for long periods, in a way to limit in the maximum extent the exposition of the persons to the electromagnetic waves generated by electrical and/or telecommunication plants included in these environments.

The absorbing tiles, that in the following figures are each inscribed with the number 5, are able to perform the function of absorbing efficiently the microwaves emitted by industrial microwaves ovens and the electromagnetic radiations emitted by electrical plants included in rooms and/or paved surfaces.

Fig. 1 shows an absorbing tile 5 according to the present invention, obtained with the material that will be described, without the application of at least a coating layer on the entire external surface.

Such a tile 5 is shaped preferably with a rectangular parallelepiped shape with a limited thickness and with the side of such a size to adapt itself on all the surface to be covered and shielded against the electromagnetic radiations. Such sides are made with a length slightly greater than the width, but each tile may be made also with different geometric shapes with respect to the rectangular parallelepiped one of the described tile, and with variable sizes, for adapting itself on products to be shielded with surfaces of different sizes. Each absorbing tile is obtained with a mixture of materials at environmental temperature, composed by powders of materials which absorb the electromagnetic radiations with the desired wavelength, which are mixed with cement, with the ratio that will be described soon.

In the example shown, in which there are described the material of the mixture of the tiles utilized for shielding products covered with the same tiles from the radiations with frequencies variables between 2 and 3 GHz, that is high frequency radiations.

The powders utilized for forming such a mixture of materials are the following :

- graphite, with a percentage comprised between 5% and 60% in volume of the graphite with respect to the remaining part of all the other materials which are utilized ;

- carbon black, with a percentage comprised between 0% and 20% in volume of the carbon black with respect to the remaining part of all the other materials which are utilized ;

- iron powder, with a percentage comprised between 5% and 40% in volume of the iron powder with respect to the remaining part of all the other materials which are utilized ;

- silicon carbide, with a percentage comprised between 5% and 60% in volume of the silicon carbide with respect to the remaining part of all the other materials which are utilized ;

- cement, preferably white cement, with a percentage comprised between 20% and 70% in volume of the cement with respect to the remaining part of all the other materials which are utilized. The above described powders of materials are used to absorb the energy of the electromagnetic radiations and, in the described example, the energy of the frequency greater than the ones specified, that are utilized especially in the tunnel-shaped ovens of the industrial type, for treating products of various kind, as for example food, pasteurizing processes, processes for cooking, painting, glueing, drying (as in the case of products of wood to be dried for being then utilized for various applications), and any other process requiring the application energy. The specified powders of materials are mixed to each other and with powdered cement, with the above cited percentages, and the mixture of the powders with the cement is randomly carried out with water, in a cold way that is at environmental temperature, by obtaining a mixture, that is poured into shaped dies (not shown), which are dimensioned and shaped for obtaining the absorbing tiles of the desired shape and size, respectively.

Subsequently, the mixture, that has poured into each die, it is not touched anymore and is let to rest up to obtain the complete drying of the same mixture. The drying of the mixture of each absorbing tile is obtained in a natural way to the air, or it may be also obtained in a fast way, by means of heat produced by heating elements, preferably of the electrical type, associated to the relative dies, without exceeding the maximum heating temperature of 150°C.

According to the invention, the mixture of each tile 5 may be obtained by using at least one type of powder or also one or more types of powders described above, obviously with the cement and the water and by leaving drying the all mixture as described.

If the absorbing tile 5 must be utilized in environments or machines dedicated for food purposes, for shielding such environments from the energy of the electromagnetic radiations, generated for example by electrical plants included in these environments, the absorbing tiles 5 may be realized not only without surface coating, as visible in Fig. 1, wherein the tiles are blackened because of the black carbon, but they may be also covered on the entire external surface thereof by at least a coating layer 6 constituted for example by white cement, as visible in Fig. 2, wherein the tiles are white, without thereby softening the shielding effect. The absorbing tiles 5 may so be applied on surfaces of paving and/or of walls of rooms and/or inhabited environments under which there are installed electrical plants to be shielded from the electromagnetic radiations, or from external electromagnetic radiations made by telecommunication plants, thereby obtaining the effect to shield these rooms and/or environments from such electromagnetic radiations, and it is not necessary to use any other type of shielding device against the same radiations.

The absorbing tile 5 may be obtained also by mixing one or more of said powders absorbing the electromagnetic radiations with the mortar (in this case, formed by cement and sand), by producing in this way plasters, masonry or floors performing the function of this kind of components of buildings, as well as that of shielding from the electromagnetic radiations, generated by the electrical plants installed below such plasters, masonry or floors or fields produced outside the building. Fig. 3 shows an absorbing tile 5 sectioned in the longitudinal direction, in the middle of the width thereof, in which it is noted that the entire tile is with the same blackened aspect of the one of fig. 1, whereas Fig. 4 shows an absorbing tile 5 with the same sectioned view of Fig. 3 on whose entire external surface there is applied the coating layer of white cement 6 of Fig. 2, in which in this case it is noted that the entire coating 6 appears white, whereas the front side 7 of the tile appears of the same blackened color of the tile of Fig. 2.

Referring now to fig. 5, it is noted an absorbing tile with a different structural shape, shape as a raceway 8 with a lower concave bent portion 9, delimiting an inner cavity 10, into which electric conductors 11 of electric plants may be housed, and which raceway is extended for the respectively desired lengths, for being installed also in this case for example below floors, walls and the like of inhabited buildings.

In this case, the raceway 8 is covered at its upper portion by a plug 12, secured on the raceway and having the same length thereof, in a manner to shield outward the electromagnetic radiations generated by the electric conductors 11. This raceway 8 is obtained by pouring said mixture of materials into dies (not shown) shaped also with a different shape than the one described. One example of application of these raceways 8 for housing electric conductors 11 may be below the floors of great shopping centers. Fig. 9 shows a front perspective view of a raceway 8 with the same component parts of Fig. 5, and for the entire width thereof, and the electric conductors 11 housed inside such a raceway 8.

Fig. 6 shows now an absorbing tile 5 inside which there are embedded electric conductors 13, arranged aligned to each other for the entire length of the tile, and in this case this structural shape of the tile 5 is also obtained by pouring said mixture of materials directly on all electric conductors 13 inside suitable dies (not shown).

Fig. 7 and 8 show various absorbing tiles 5 according to the invention, identical and joined to each other, and ready for being installed in the desired positions, wherein in Fig. 7 all the tiles are without surface coating, whereas in Fig. 8 all the tiles are covered by a surface coating 6, identical to the one of Fig. 2.

Fig. 10 shows several absorbing tiles 5 identical and joined to each other in the direction of their width, and without surface coating, and in which there are embedded electric conductors 14, which are arranged aligned to each other for all the tiles, and this shape is also obtained as the one of the unique tile of Fig. 6.

Finally, Fig. 11 shows a tunnel-shaped apparatuses 15 of the industrial type, for treating products of various kind by microwaves, provided with absorbing tiles for the shielding against the electromagnetic waves.

This apparatus 15 for treating by microwaves is shaped with a loading structure 16 supported on the floor by two vertical supports 17 and 18, and shaped with a conveyor belt 19 for the products to be treated, with two vertical structures 20 and 21 delimiting a treatment inner chamber (not shown), and with a first and a second attenuator stage 22 and 23, arranged on the loading structure 16, and on each one of which said absorbing tiles 5, according to the invention, are fixed to (not visible in Fig. 11).