System and method for delivery of electromagnetic waves in to enclosed space

FIELD OF THE INVENTION

The present invention relates to a method and system for distributing electromagnetic waves, and more particularly, to the supply of electromagnetic waves to an enclosed space through a low pass structure of a radio frequency signal using directional antennas placed in a dielectric environment.

Description of the technical level

A radio signal can enter an enclosed space, such as a building, in two ways, usually through the windows of a building or through the walls of a building. Buildings do not always have windows of sufficient size, sometimes with structures that prevent the propagation of electromagnetic (EM) waves, such as fine gratings or metal mesh, from being installed on the windows. Brick, concrete, or reinforced concrete walls greatly attenuate radio waves by reflecting them. In other cases, such as in the case of signals transmitted by georadar antennas through objects composed of low-transmittance materials of electromagnetic waves, the resolution and dynamic range of georadars are reduced by the partial reflection of the transmitted signals from the object surface between the transmitting antenna and the object. to pass the signal sent, there is a space.

Patent no. U.S. Pat. No. 6,014,546 (A) describes a system and method for distributing a radio frequency signal in a building or other structure that is not conductive to radio frequencies. The radio signal is transmitted wirelessly from the base station to an antenna on the building to the receiver, from which the signal is transmitted to the interior of the building by wire, connecting the antenna on the building to an indoor antenna that distributes the radio frequency signal inside the building. The main disadvantage of this system is that the receiver on the building needs to be wired to the signal splitter inside the building.

Patent no. U.S. Pat. No. 6,895,218 (B2) describes a method for transmitting a wireless signal inside a building and distributing a radio signal inside the building. The radio transmitter receives a wireless signal from the base station. The transmitter changes the frequency of the received signal and transmits it wirelessly to the mobile station interface connectors inside the building. The mobile station inside the building changes the frequency of the transmitted signal to the original frequency and forwards it to the mobile signal receiver inside the building. The main disadvantages of this method are receiving a signal from the base station that uses it

LT 6255 B omnidirectional antenna, where in order for the signal received from the base station to enter the building and be received there by mobile devices, the changed frequency signal must be received at the radio frequency signal receiver outside the building, where the signal frequency is changed. to the original frequency before dispatch.

Patent no. U.S. Pat. No. 8,121,540 (B1) describes a system and method for transmitting a wireless signal to a building. The repeater system used is designed to transmit the signal received outside the building through the glass using antennas inside and outside the building that exchange information. The main disadvantages are the use of frequency converters, the need to install an antenna inside the building, as well as the application of the system and method through glass.

U.S. Pat. No. 6,771,206 (B2) describes a method and system for transmitting a wireless signal to an enclosed space. The device in use sends electromagnetic signals from the signal generator via the transmitting antenna to the ground so that they are reflected from the surface of the objects in the depths of the earth or the cavities back to the device for recording. The main disadvantage of the present invention is that said signal transmitting antenna is above the ground, thus forming parasitic signals reflected from the ground, thereby reducing the penetration of electromagnetic waves onto ground objects.

Patent application no. WO03058850 (A2) describes an apparatus and method for improving wireless communication transmission between a building's exterior and interior is closest to our invention. The radio frequency signal is transmitted to the interior wall of the building via a primary receiving device on the building, which has at least one antenna for communication with the indoor antenna, wherein at least one antenna in said device has a reflector for transmitting the radio signal to the wall of the building. direction. The outdoor unit receiving the primary signal has at least one second antenna for communication with the base station antenna transmitting and receiving the radio signal. The main disadvantage of the system is that the antenna that directs the radio frequency signal to the building wall is not mounted in the same dielectric constant material as the building wall, which makes it impossible to achieve the maximum signal strength inside the building wall.

All these disadvantages are eliminated by the wireless supply of a radio frequency signal through a partially or completely enclosed space-limiting material by means of a system in which a signal for transmission is generated in a signal generating device via said space-limiting barrier, such as a masonry, concrete or reinforced concrete wall or ground, whose signal is transmitted by wires to at least one directional antenna on said space-limiting object, which is confined to the surface of said enclosing object and is placed in a material of dielectric permeability close to the material of the enclosing object, wherein the inner surface of the enclosing object in front of which said antenna is mounted is covered with a layer of material having a lower electromagnetic refractive index than the refractive index of electromagnetic waves on the surface of said enclosed space, thereby further increasing the bandwidth of said enclosed space bounding object to the radio frequency signal.

The essence of the invention

A radio frequency wave signal, which is an electromagnetic (EM) wave, can normally enter an enclosed space, such as a building room, through the windows, doors, or walls of a building. Ensuring proper radio frequency signal strength in confined spaces is an important issue when the material of the walls of buildings strongly attenuates the signal. Buildings do not always have windows of sufficient size, sometimes with structures that prevent the propagation of EM waves, such as small grilles or metal mesh. The propagation of EM waves depends largely on the material in the signal path, allowing the signal to attenuate. One reason is absorption. If the signal is not reflected from the object, does not bypass or pass through it, then complete signal absorption occurs. Most materials absorb some of the radio frequency signal in all cases. Brick and concrete walls will absorb the signal much more strongly than, for example, gypsum-based walls. Another important effect on radio frequency signal quality is reflection. The signal is a reflection from any surface whose dielectric constant is different from the ambient dielectric constant. Most often, the signal is a reflection from flat surfaces such as smooth building walls, road surface, water, and so on. Also, the farther the direction of signal propagation is from the perpendicular surfaces, the more the signal is reflected, even full reflection is possible. Sometimes, for example when a mobile suppressor with an antenna facing the building is used, the reflection of EM waves from the walls of the building is particularly undesirable because it causes communication interference where it is not needed and reduces the signal where it is needed.

The invention is intended to address specific problems such as unwanted reflection of radio frequency waves from obstacles such as building surfaces, insufficient signal level in some rooms and excessive signal level in other rooms, the possibility of sabotage arising from the installation of mobile suppressors in prisons. The invention can also be used to increase the operating distance of georadars and to reduce the amount of interference therein.

The object of the invention is to provide a radio frequency signal to an enclosed space by means of radio frequency signal reflecting materials which limit said enclosed space, a method and a system, in particular for signal transmission through high attenuation barriers such as masonry, concrete or reinforced concrete walls, thick glass, to the premises of special purpose buildings, such as prison cells, so that that unauthorized persons are not allowed to influence the signal generation and transmission equipment, and that the installation of the system does not require the dismantling of the wall on which the system is to be mounted, such as drilling a wall and the like. It is also an object of the invention to provide a radio frequency signal to an enclosed space through radio frequency signal reflecting materials which limit said enclosed space, a method and a system for improving, in particular the transmission of the signal via high attenuation barriers such as earth.

To solve the above problems, we suggest using at least one directional antenna placed in at least one dielectric environment, which should be attached to the surface of the enclosing material, such as a masonry, concrete or reinforced concrete wall, roof, floor, glass, ground or the like, from the outside. the sides of the object enclosing the enclosed space. It is proposed to use several antennas, depending on the number of rooms in the building, and to distribute the signal between them by wired signal transmission means, such as wires or cables from the radio frequency signal generating unit. The system may also include other additional devices that may be required depending on the application environment.

Brief description of the drawing figures

FIG. 1 provides an antenna that is placed in the environment of a natural or artificial dielectric and is attached to the surface of a building;

FIG. 2 is an antenna disposed in the environment of a bulk dielectric in an easily deformable container;

FIG. 3 shows a schematic diagram of a radio frequency signal distribution system.

Description of the Best Mode for Carrying Out the Invention

EM waves are reflected as they propagate from one environment to another with a different dielectric constant. The air dielectric constant ε is about 1, and for objects such as building walls - about 5 to 10. For this reason, electromagnetic waves falling on the building wall or similar dielectric permeable object will be reflected and the space inside the building or other object will reach only part of the wave energy. The proportion of reflected energy can be estimated using Fresnel formulas: in the case of a wave perpendicular to the surface, when the intensity of the incident wave is / and that of the reflected wave is h. the reflection factor r will be \ n i + n2 // where n = ^ [εμ is the refractive index, μ is the magnetic permeability (usually μ = 1). If the EM wave propagates in air with nj = 1 and falls on an obstacle with Π2 = 3, then r = 1/4 and / ^ = // 4. Taking only the first reflection would reflect a quarter of the EM wave energy from the outer surface of the obstacle. If the wave does not fall at a right angle, the reflection would be even stronger (even full reflection is possible). If the wave propagated from an environment with a refractive index ni = ri2, then r = 0, and there would be no reflection from the outer surface at all.

To avoid reflection from an obstacle such as a building wall, an additional layer or layers can be used on the building wall (101) at least on the inner and / or outer surface, which work on the same principle as optical lens illumination, ie in the simplest case a layer of wavelength thick material with an impedance of:

^ layer ⁼ y] or o ^ walls · (2)

Since Ζ ~ 1Λ1ε, and Eoro ^ l, is called £_s/_{ooi (sn}=^£_s/ enos · However, it would be very expensive to cover the building with a lightening layer.

In one embodiment of the invention, such as the installation of mobile interference systems in prisons, remotely emitted reflected waves are particularly undesirable because the reflected interference signal would travel outside the facility and the signal entering the premises of the prisons would be weaker. In order to avoid unwanted reflections from the external surface of the building and to be able to control the signal power in different parts of the building, it is necessary to use antennas attached to the surface of the building, which face the wall. However, it is difficult to design an antenna to radiate into a wall because additional reflection occurs between the antenna and the wall. To solve this problem, the antenna (102, 301) is placed in the environment (103) of a natural or artificial dielectric whose dielectric constant is close to the dielectric constant of the building wall (101). In this way, the design principles of the antenna (102) will not differ from the design principles of airborne antennas, since the antenna will be in an isotropic environment as well as air (103). In this way, reflections of EM waves and thus resonant phenomena associated with parasitic reflections from the outer surface of the wall (101) are avoided, which is particularly relevant in the design of antennas. The dimensions of the antenna (102, 301) (they are proportional to the wavelength) will be smaller because the wavelength λ in the dielectric is proportional to the environment:

λ ~ 1 / Ve. (3)

If the ambient dielectric constant ε is 4, all dimensions of the antenna (102) would decrease by 2 times and the volume by 2³ times - t, y, 8 times. In order to further improve the signal transmission through the wall (101), a reflection-reducing layer (106) with a dielectric constant e can be installed at least on the inner side of the wall._siuosn = ^ £ walls, and thickness - a quarter wavelength. In order to reduce reflections over a wide frequency range, several layers of different dielectric constant should be applied. If the antenna (102) has its own reflector or is directional, then a metal surface (104) delimiting the dielectric environment (103) and reflecting the EM waves emitted by the antenna is not necessary. Without the use of the antenna (102, 301) in the dielectric environment (103) and / or the illuminating layer (106) from the inside, the signal entering the room through the concrete or reinforced concrete wall (101) is substantially attenuated.

Depending on the specifics of the prisons, the radio supply system inside the building comprises a number of antennas (102, 301) located on the outside of the building walls (101), covering all frequencies used by the transmitter, typically 0.4-6 GHz and housed in a dielectric environment. (103) also has an EM wave reflecting element (104), such as a metal surface, or other type of reflector, an electromagnetic wave generating unit (302) which signals to said antenna (102). 301) transmits using at least a wired signal transmission means, such as wires (105, 303). The system may also include additional signal processing means, depending on the specifics of the system application. Said antenna (102, 301) in the dielectric material (103) can be mounted on substantially any plane (101) of the building, such as a wall, window, roof, floor and the like, by mechanical means. The mounting method has no appreciable effect on the antenna's performance. The system may further comprise at least an inner wall-mounted electromagnetic reflection reducing layer (s) (106).

In another embodiment of the invention, a space for supplying electromagnetic waves to a closed, or at least partially closed, space using a system comprising at least an antenna (202) in a dielectric environment (203) and at least a signal (205) for transmitting wires (205) to said antenna (202) generating unit (302), the method may be applied to georadars that use radio signals to probe the earth (201), ruins, and the like. A georadar is a device that generates a broad-spectrum signal, radiates it to earth, and captures a response. The response determines the size and location of inequalities in the ground. The directional antenna (202) is placed in an easily deformable container (204) with a deformable, preferably bulk dielectric material (203), such as sand, therein. This would ensure that only minimal reflections of EM waves from the ground surface are generated (201). The reflection factor calculated according to formula (1) will depend on the exact coincidence of the dielectric constant of the material (203) in the container (204) and the ground (201), as well as how close the container (204) is to the surface of the ground (201).