WO2024157295A1

WO2024157295A1 - Apparatus for creating radiofrequency images and corresponding method

Info

Publication number: WO2024157295A1
Application number: PCT/IT2024/050015
Authority: WO
Inventors: Luca Marcaccioli; Hamza EL GHANNUDI; Lucio ACCARDO; Stefano BRUNORI; Marco CAPODURI
Original assignee: Rf Microtech S.R.L.
Priority date: 2023-01-25
Filing date: 2024-01-25
Publication date: 2024-08-02

Abstract

Apparatus (10) for creating radiofrequency images comprising a radar unit (11) for transmitting and receiving radiofrequency signals (S1, S2), a reflecting unit (12) comprising transceiver elements (13), and a processing unit (14) connected to the radar unit (11), and corresponding method for creating radiofrequency images according to the invention.

Description

“APPARATUS FOR CREATING RADIOFREQUENCY IMAGES AND CORRESPONDING METHOD”

FIELD OF THE INVENTION The present invention concerns an apparatus for creating radiofrequency images and a corresponding method. Advantageously, but not exclusively, the apparatus according to the invention can be used for creating images in two or three dimensions in many different technical fields, for example for medical, construction, industrial, safety or security applications, or in production, packaging or logistic industries, or suchlike.

BACKGROUND OF THE INVENTION

Radiofrequency images are visual reproductions that represent the dielectric characteristics of a certain scenario/object at radio frequencies (0 - 100 GHz). All materials interact differently with radio frequencies, and depending on the frequency used: conductors are, for example, fully reflective, while plastics are partly transparent, as are the walls of a building, especially at low frequencies. Radiofrequency images basically associate these properties with the intensity and/or color of a pixel, thus allowing to generate optical images that can be associated with the physical characteristics of the object/scenario observed. Apparatuses for creating radiofrequency images are known, comprising a transmitting antenna that sends electromagnetic waves toward one or several objects to be imaged, for example toward the human body in medical applications. In such apparatuses, the part of the electromagnetic wave reflected on the surface of the sample is collected, by the same antenna in monostatic apparatuses, or by a different receiving antenna in bistatic apparatuses, on a known two-dimensional

(2D) or three-dimensional (3D) plane.

In bistatic apparatuses, a single antenna can mechanically scan the 2D/3D plane to reconstruct the image of the object, or target. Alternatively, an array of antennas can be used on a first dimension (ID) that is mechanically scanned on a second dimension in order to obtain a 2D image. To further reduce the scanning time, a two-dimensional array of antennas can be used.

In other apparatuses, known as S ARs (synthetic aperture radars), a radar antenna is used to create two-dimensional or three-dimensional images of objects or zones of the earth. A SAR uses the movement of the radar antenna on a target zone to supply a finer spatial resolution than the known stationary apparatuses as above. For example, the SAR can be positioned on board an aircraft or a vehicle: in motion, the position of the antenna with respect to the target (which in this case is the scenario below being observed) changes over time. The processing of the signal of the subsequent recorded radar echoes allows to combine the recordings from these multiple positions of the antenna. This method defines the synthetic aperture of the antenna and allows to create radiofrequency images with a higher resolution than would otherwise be possible with a stationary antenna. Apparatuses for creating radiofrequency images based on programmable transmission arrays are also known, comprising arrays of antennas which are able to be programmed with respective transmission coefficients in order to direct a microwave beam from the microwave source toward a position on the target. The antennas are also able to be programmed with respective additional transmission coefficients in order to receive a beam reflected from the position on the target and direct it toward a microwave receiver. A processor can be driven to measure an intensity of the reflected beam in order to determine a value of a pixel within an image of the target. Multiple beams can be directed toward the target to obtain corresponding pixel values for the reconstruction of the image. Known apparatuses have highly complex hardware and software architectures, and high implementation and production costs. Known apparatuses also do not allow to detect the transmissive properties of the material/scenario under observation, but only the reflective ones.

US 2015/276928 Al describes an apparatus comprising a scattering antenna, a reflector antenna and circuitry arranged to image an object. The antennas comprise metamaterial elements and their position can be adjusted. The apparatus circuitry configured to produce an image of an object that is illuminated by the series of beam patterns using a compressive imaging algorithm and to receive a series of signals corresponding to a detected amount of energy and produced by the scattering antenna.

US 2013/093611 Al describes an apparatus and method for imaging a volume for security purposes comprising an antenna array formed by set of panels each containing a sub-array of antennas and each reflecting energy from multiple of RF energy source (horns) onto the subject to be scanned and back to the horns. This solution run complex algorithms to determine and compensate for the mechanical misalignment between panels or array of the antenna, which could causa a blurring or smearing of the image in the overlap region where two or more panels are scanning simultaneously.

CN 115453525 A describes a RIS (Reconfigurable Intelligent Surface)-based radio perception imaging method for imaging objects positioned in a spatial region that is first discretized to obtain multiple discrete points, and then optimized. The method provides to evaluate the signals reflection strength through calculations with matrices.

US 2021/255312 Al describes an imaging method and device which provides to transmit a radiation at a target (for example a chipless RFID tag) during relative movement between the imaging device and the target and produces backscatter radiation data in response to receiving backscatter radiation from the target. The device comprises a radar for emitting the radiation and an auxiliary device for taking into account of the relative movement.

None of these solutions offer simplified apparatus and method able to create images since they are computationally heavy, costly and complex to implement.

There is therefore the need to perfect a radiofrequency apparatus for creating radiofrequency images that can overcome at least one of the disadvantages of the state of the art.

To do this, it is necessary to solve the technical problem of identifying a configuration of the hardware and software architecture that is alternative to existing systems, such that it will allow an advantageous reduction in the complexity as well as in the costs of the apparatus.

In particular, a purpose of the present invention is to provide an apparatus for creating radiofrequency images, and to develop a corresponding method for creating radiofrequency images of one or several objects.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes and to resolve the technical problem disclosed above in a new and original way, also achieving considerable advantages compared to the state of the prior art, an apparatus for creating radiofrequency images according to the present invention comprises a radar unit for transmitting and receiving first and second radiofrequency signals, a reflecting unit comprising one or several transceiver elements, each configured to receive a first radiofrequency signal from said radar unit and generate a corresponding second radiofrequency signal to be retransmitted toward said radar unit, and a processing unit connected to the radar unit and configured to process said second radiofrequency signals and use them to reconstruct 2D or 3D (two- or three- dimensional) radiofrequency images.

In accordance with one aspect of the present invention, said one or several transceiver elements are configured to modify the received first radiofrequency signal to generate univocally identifiable second radiofrequency signals so as to create a one-to-one correspondence between the emitted second radiofrequency signals and the transceiver elements of their emission.

In accordance with one aspect of the present invention, the processing unit is configured to know the spatial arrangement of said one or several transceiver elements so as to create radiofrequency images based on the distribution pattern of said second radiofrequency signals, which reflects said spatial arrangement of said one or several transceiver elements.

The fact that the position of each transceiver element of the reflecting unit is known a priori, allows to associate each univocally identifiable radiofrequency signal retransmitted by the reflecting unit to a univocal path, therefore to a spatial position and therefore to a pixel of an image, the color/intensity of which will be assigned by the processing unit based on the type of interaction that the radiofrequency signal has had with matter, which can in turn be deduced from the type of modification that the radiofrequency signal has undergone.

The images can therefore be associated with the characteristics (for example attenuation and/or phase) of the radiofrequency signal, which is retransmitted by the reflecting unit, which passes through the same portion of the object twice. By being able to associate each univocally identifiable radiofrequency signal with a univocal path, the analysis of the signals becomes technically simpler and faster, the acquired images can be arbitrarily accurate (based on the density of the reflecting unit), and the computational complexity for the creation of the images is reduced.

It is therefore possible to use a less complex hardware and software architecture compared to known apparatuses, and reduce implementation and production costs.

It is also possible to detect the transmissive properties of the object under observation, a characteristic amplified by the fact that the same signal passes twice through the object interposed between the two units.

The apparatus is also suitable for acquiring images of objects hidden by other objects that are transparent or partly transparent to the radio frequencies used.

In accordance with another aspect of the present invention, the one or several transceiver elements of the reflecting unit comprise coding means configured to generate the univocally identifiable radiofrequency second signals by generating an identification code. The identification code can be generated through the modulation of the first radiofrequency signal received. The reflecting unit can also amplify the signal received before retransmitting it.

In accordance with another aspect of the present invention, the reflecting unit can consist of a single transceiver element positioned in one point in space, or consist of several elements positioned according to an arrangement chosen in the group consisting of: a linear one-dimensional configuration, a flat two-dimensional array, a curved two-dimensional array, or a scattered and not contiguous points. Each element can be made with one or several transceiver antennas, or one or several receiving antennas and one or several transmitting antennas, operating even in different polarizations from each other: for example, it is possible to receive in vertical polarization and transmit in horizontal polarization.

In accordance with another aspect of the present invention, the processing unit is configured to associate the characteristics of each second radiofrequency signal modified by a corresponding transceiver element of the reflecting unit with the color and/or intensity of a pixel of the aforementioned images.

In accordance with another aspect of the present invention, the radar unit can comprise one or several transceiver elements, or one or several transmitting elements and one or several receiving elements. Each of such elements can in turn consist of a single antenna or an array of antennas. Each of such elements can operate in any polarization whatsoever.

In accordance with another aspect of the present invention, the processing unit is configured to know the spatial arrangement of said one or several transceiver elements or of said one or several transmitting elements and one or several receiving elements of the radar unit.

In accordance with another aspect of the present invention, the apparatus comprises, or cooperates with, one or several vision devices selected from optical and/or infrared image detectors.

In accordance with another aspect of the present invention, the processing unit is configured to correlate said radiofrequency images with the optical and/or infrared images detected by said optical and/or infrared image detectors.

Advantageously, in this way it is possible to correlate or overlap the electromagnetic image with the optical and/or infrared image, and detect the object even when it is no longer visible with other methods, or detect multiple physical characteristics thereof.

In accordance with another aspect of the present invention, a method for creating radiofrequency images, comprises the steps of: - sending, by means of a radar unit, a first radiofrequency signal toward a reflecting unit, comprising one or several transceiver elements, of the apparatus, in a forward path;

- acquiring, by means of said one or several transceiver elements of the reflecting unit, the first radiofrequency signal; - generating, by means of said one or several transceiver elements, a corresponding second radiofrequency signal;

- further sending, in a return path, the second radiofrequency signals to the radar unit;

- further acquiring, by means of said radar unit, said second radiofrequency signals;

- processing, by means of a processing unit connected to the radar unit said second radiofrequency signal in order to reconstruct radiofrequency images.

In accordance with another aspect of the present invention, the method further comprises:

- modifying, by means of said one or several transceiver elements, the received first radiofrequency signal and generating univocally identifiable second radiofrequency signals so as to create a one-to-one correspondence between the emitted second radiofrequency signals and the transceiver elements of their emission;

- communicating to the processing unit the spatial arrangement of said one or several transceiver elements so as to create radiofrequency images based on the distribution pattern of said second radiofrequency signals, which reflects said spatial arrangement of said one or several transceiver elements.

In accordance with another aspect of the present invention, the method comprises modulating, by means of coding means, and in some cases amplifying, the first radiofrequency signal received by the transceiver elements in order to generate an identification code that univocally identifies the second radiofrequency signals.

In accordance with another aspect of the present invention, the method comprises the steps of positioning one or several objects in a shooting space defined between said radar unit and said reflecting unit and illuminating the one or several objects by means of the first radiofrequency signal sent by the radar unit in the forward path, and by means of said univocally identifiable second radiofrequency signals in the return path.

Advantageously, since electromagnetic waves pass through the object, it is possible, in certain geometric conditions and with a suitable number of antennas in the radar unit and/or in the reflecting unit, to obtain the transmissive properties, including internal ones (3D scanning), of the object under observation.

Moreover, it is possible to use single or double polarization antennas both in the radar unit as well as in the reflective unit, thus offering the possibility of illuminating the object with different polarizations, or varying the response polarization of the elements of the transceiver units, in order to observe differences in the properties of the object based on polarization and thus detect further physical properties of the object observed.

In accordance with another aspect of the present invention, the steps of sending, acquiring, generating, further sending, further acquiring, processing, modifying and generating, and communicating are repeated cyclically at a high frequency, comprised in a range that goes from 1 GHz to 1 THz, by a control unit configured to control and command the operation of the apparatus in order to make said apparatus operate in real-time in order to create films or videos.

In accordance with another aspect of the present invention, a use of an apparatus for creating radiofrequency images as define above is provided for creating 2D or 3D (two- or three- dimensional) radiofrequency images of objects positioned in a shooting space defined between said radar unit and said reflecting unit.

In accordance with another aspect of the present invention, a use of an apparatus as define above is provided for calculating the distance of each of said transceiver elements of said reflecting unit from said radar unit after said processing unit has detected the images of a shooting space defined between said radar unit and said reflecting unit.

In this latter case, the processing unit is configured to detect the images of the shooting space and associate them with a variation of the distance of each of the elements of the reflecting unit. The information associated with the images will not in this case relate to objects located in the aforementioned shooting space, but it will consist of information linked to the different depths caused by the different distances of each of the elements of the reflecting unit.

Advantageously, in this case the type of signals transmitted/received, and the processing unit can be configured in such a way as to calculate the distance of each of the elements of the reflecting unit. Since it is therefore possible to detect even small variations of the distance of each of the elements of the reflecting unit, it is possible, for example, to use this reflecting unit as a platform for measuring weight distribution, where the displacement of each element can be correlated to the overlying weight, for example in the creation of baropodometric platforms.

In accordance with another aspect of the present invention, a use of an apparatus as define above is provided for identifying an object by reading a code that is univocally associated to said object, wherein said code comprises one or more parts placed on an external surface of said object or embedded therein, and wherein said code is defined by the configuration, or by the geometrical arrangement, or by the permittivity of said one or more parts.

DESCRIPTION OF THE DRAWINGS These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a three-dimensional view, during use, of an apparatus for creating radiofrequency images according to the present invention, in which even an object to be illuminated by the apparatus is shown in a shooting space;

- fig. 2 is a front view of a detail of the apparatus for creating radiofrequency images of fig. 1;

- fig. 3 is a lateral view of the apparatus for creating radiofrequency images of fig. 1;

- fig. 4 is a lateral view, during use, of an apparatus for creating radiofrequency images according to another embodiment;

- fig. 5 is a three-dimensional enlarged view of an object to be illuminated with the apparatus of the present invention. We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims. To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION With reference to fig. 1, an apparatus 10 for creating radiofrequency images according to the present invention comprises a radar unit 11 for transmitting and receiving first and second radiofrequency signals SI, S2, a reflective unit 12 comprising one or several transceiver elements 13, and a processing unit 14.

The apparatus 10 also comprises a control unit 15 configured to control and command the operation of the apparatus 10.

The control unit 15 can comprise a processing module, or CPU, a storage module and auxiliary circuits, such as input/output circuits.

For example, the processing module can be any form of microcontroller, microprocessor, computer processor or suchlike, usable in computing for processing data for the control of radiofrequency apparatuses. The storage module can be connected to the processing module and be one or several commercially available memories, such as a random access memory (RAM), a read-only memory (ROM), a hard disk, a mass memory, or any other form of digital, local or remote storage whatsoever. Software instructions and data can for example be coded and stored in the storage module to command the processing module.

According to a preferred embodiment, and as shown in the drawings, the transmitting and receiving radar unit 11 can comprise a transmitting element 16 comprising a single antenna, and a receiving element 17 comprising a two- dimensional array of antennas 18. According to alternative embodiments, not shown in the drawings, the radar unit 11 can comprise several transmitting and/or receiving elements, and each element can be formed by a single antenna or by onedimensional or planar arrays of antennas, with single or double polarization.

The transmitting element 16 is configured to send a first radiofrequency signal SI toward the reflecting unit 12.

The reflecting unit 12 comprises one or several transceiver elements 13, each formed by a single transceiver antenna. According to alternative embodiments, the transceiver elements 13 can be formed by a single transceiver antenna or by onedimensional or planar arrays of antennas, with single or double polarization.

In particular, the transmitting element 16 is configured to send a plurality of first radiofrequency signal S 1 , each of these signals being directed toward a respective transceiver element 13. Some of these first radiofrequency signals SI have been shown by way of example in figs. 1 , 3 and 4 with continuous stroke lines.

The receiving element 17 of the radar unit 11 is configured to receive second radiofrequency signals S2 sent by the transceiver elements 13.

In particular, the receiving element 17 is configured to receive a plurality of second radiofrequency signal S2, each of these signals having being reflected by a respective transceiver element 13. Some of these second radiofrequency signals S2 have been shown by way of example in figs. 1 , 3 and 4 with dashed and dotted lines.

The number of transceiver elements 13 is correlated to the sizes of the objects 100 to be detected and/or measured, and to the granularity with which the image is to be reconstructed. The size of the transceiver elements 13 is proportional to that of the radiating elements, which is inversely proportional to the frequency of use. The number of transceiver elements 13 to be used in the reflecting unit 12 is therefore arbitrary and depends on the conditions of use. There is no upper limit, except for the signal processing capability.

The transceiver elements 13 are configured to receive the first radiofrequency signal SI transmitted by the radar unit 11 and to modify it so as to make it univocally identifiable, generating a corresponding second radiofrequency signal S2 to be retransmitted toward the radar unit 11. In particular, each second radiofrequency signal S2 generated comprises an identification code of the transceiver element 13 itself. In this manner, a one-to-one correspondence is created between the second radiofrequency signals S2 and the transceiver elements 13 whose emitted such signals.

The transceiver elements 13 comprise coding means 21 (figs. 1 and 2) for generating the aforementioned identification code through the modulation of the respective second radiofrequency signals S2. The coding means 21 can be modulators, preferably phase or frequency modulators, possibly amplitude or code modulators. Amplification elements may be added to improve the performance of the apparatus 10, in order to achieve a better signal/noise ratio. The transceiver elements 13 are positioned according to an arrangement chosen in the group consisting of: a linear one-dimensional series, a flat two-dimensional array (as shown in the drawings), a curved two-dimensional array, or scattered and not contiguous points.

The transceiver elements 13 are positioned in such a way as to direct their transceiver (or receiver/transmitter) antennas toward transmission surfaces 23 and reception surfaces 24 of the radar unit 11. For example, and as shown in figs. 3 and 4, the transceiver elements 13 are positioned with the normals to the surfaces 22 of the transceiver antennas having parallel direction and opposite orientation to the direction and orientation of the normals to the transmission surfaces 23 and reception surfaces 24. In other words, in the embodiments shown in figures 3 and

4 the radar unit 11 and the receiving unit 12 are oriented to lie in parallel plane.

A shooting space SR is therefore defined between the radar unit 11 and the reflecting unit 12. In particular, the shooting space SR is the space subtended by the radiation cone delimited by the first radiofrequency signals SI transmitted by the transmitting element 16 to the transceiver elements 13 placed at the corner of the reflecting unit 12, as shown in fig. 1.

The shooting space SR is comprised between the radar unit 11 and the reflecting unit 12.

In this shooting space SR, during use, it is possible to position objects 100 to be observed under the profile of its properties of interaction with the radio frequency. The apparatus 10 is therefore suitable to acquire radiofrequency images of the objects 100 located in the aforementioned shooting space SR. By the term “objects” we mean any physical body whatsoever, including material objects such as a car, a suitcase or suchlike, people or animals.

According to another possible use, the apparatus 10 is also suitable to detect even small variations of the distance of each of the transceiver elements 13 from the radar unit 11. It is therefore possible to use the reflecting unit 12 as a platform for measuring weight distribution, where the displacement of each transceiver element 13 is correlated to the overlying weight, for example in the creation of baropodometric platforms, or in similar applications.

In the configuration in which the radar unit 11 comprises a two-dimensional array of antennas 18 shown in the drawings, the apparatus 10 can be configured to perform real-time shooting. Advantageously, the apparatus 10 can therefore also be used for the dynamic shooting (video) of the properties of the object, as well as images.

The processing unit 14 can be comprised in the same processing module, storage module and auxiliary circuits of the control unit 15, or comprise its own processing module, storage module and auxiliary circuits as described above, with software instructions and data for image processing.

The processing unit 14 is connected to the radar unit.

The processing unit 14 is configured to process the aforementioned second radiofrequency signals S2 comprising the aforementioned identification code, and use them to construct images relating to the shooting space SR. The images are associated with the physical properties of the object 100 that may be present in the shooting space SR.

The processing unit 14 is configured to associate the second radiofrequency signal S2 coming from each transceiver element 13 with a pixel of the image.

In particular, the processing unit 14 can be configured to reconstruct images of one or several objects 100 located in the shooting space SR.

The objects 100 can in fact create a total or partial shadow zone ZO on the reflecting unit 12, according to their dielectric properties. The second radiofrequency signals S2 retransmitted by the transceiver elements 13 comprised in the shadow zone ZO will therefore be weaker or absent, or will also have a delay (phase) that depends on the thickness and characteristics of the material.

The processing unit 14 can then associate the reduced or zero amplitude of the aforementioned second radiofrequency signals S2 with the presence of the object 100 and define its shape and/or distance from the radar unit 11, or reconstruct its properties (for example thickness or permittivity, one of the two being known).

In the case of different objects 100 with different transparency to the radio frequencies used, it is possible to acquire radiographic images of the objects 100. For example, in construction applications, by positioning the radar unit 11 in front of a wall and the reflecting unit 12 behind it, it is possible to acquire images of pipes and electrical wiring inside the wall, or alterations in its composition. As an additional example, in industrial applications or at an airport control point it is possible to detect the presence and/or shape of objects 100 shielded by wrappings. According to another example, the apparatus according to the present invention can be used in the for identifying the object 100 by reading a code C that can be associated to the object 100, for example placed on the external surface of the object 100 or embedded inside it so as to be not visible at a naked eye.

The code C comprises one or more parts 101 whose configuration, or geometrical arrangement, or permittivity, define the code itself.

In the example described here, the parts 101 are made of a material having electric properties (such as permittivity) different from those of the object 100. For example, the code C may be formed by parts made of plastics, and the object 100 is made of metal, or the code C may be formed by metal parts embedded in an object 100 made of ceramics.

In the example shown the code C is formed by parts 101 embodied as a plurality of rod-shaped elements, placed parallel one another, having different shapes or geometry, for example different lengths from one another. The various combination of lengths may be univocally associated to a determined object.

These rod-shaped elements form a unique code C that can be univocally associated to each different object 100 illuminated by the apparatus 10.

This application may be usefully applied in production or packaging or transport lines to identify the object 100 travelling thereon. For example, by reading the code C with the apparatus 10, it is possible to verify which kind of object is being produced or packaged or transported.

According to this example, the second radiofrequency signals S2 passes though the object 100, will have different characteristics, for example a different magnitude, depending whether they will pass through the code C or the object 100. The processing unit 14 will read which code C is associated to the object 100 after the radar unit 11 have received the second radiofrequency signals S2 reflected back by the transceiver elements 13. ft is pointed out that this application may be used alone or in combination with the other applications described above in case there is not only the need of reconstruct the 2D or 3D image of the object 100, but also the need of identified the latter by detecting the code C associated therewith.

As an additional example, objects 100 may not be inserted into the shooting space SR and it is possible to acquire images of the reflecting unit 12. In this case, the processing unit 14 can be configured to associate the aforementioned images with a variation of the distance of each of the transceiver elements 13 from the radar unit 11.

The apparatus 10 can cooperate with one or several vision devices selected from optical 50 or infrared 51 image detectors (fig. 4).

The processing unit 14 can therefore be configured to correlate the radiofrequency image with the optical and/or infrared image and detect the object 100 even when it is no longer visible with other methods, or detect other characteristics thereof.

The operation of the apparatus 10 for creating radiofrequency images described heretofore, which corresponds to the method according to the present invention, comprises the following steps:

- sending, by means of the transmitting element 16, a first radiofrequency signal SI toward the reflecting unit 12, in a forward path; - acquiring, by means of the transceiver elements 13, the first radiofrequency signal SI;

- modifying the first radiofrequency signal SI, by means of the transceiver elements 13, generating corresponding univocally identifiable second radiofrequency signals S2 of each transceiver element 13;

- sending, in a return path, the univocally identifiable second radiofrequency signals S2 to the radar unit 11 ;

- acquiring, by means of the radar unit 11, for example by means of a two- dimensional array of antennas 18, the univocally identifiable second radiofrequency signals S2;

- processing, by means of the processing unit 14, the univocally identifiable second radiofrequency signals S2 in order to reconstruct radiofrequency images relating to the shooting space SR.

The method comprises modulating, by means of the coding means 21 , the first radiofrequency signal SI, in order to generate the univocally identifiable second radiofrequency signals S2, generating a corresponding identification code.

The method also comprises positioning one or several objects 100 in the shooting space SR and illuminating them by means of the first radiofrequency signal SI in the forward path, and by means of the univocally identifiable second radiofrequency signals S2 in the return path, and acquiring the univocally identifiable second radiofrequency signals S2 in order to construct a radiofrequency image of the objects 100 present in the shooting space SR. Depending on the configuration of use, the image can represent the complete transmissive properties of the object, even internal (3D image), or squashing them in a plane (2D image).

It is clear that modifications and/or additions of parts or steps may be made to the apparatus 10 and to the method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of apparatus for creating radiofrequency images and corresponding method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

1. Apparatus (10) for creating radiofrequency images comprising:

- a radar unit (11) for transmitting and receiving first and second radiofrequency signals (SI, S2); - a reflecting unit (12) comprising one or several transceiver elements (13), each configured to receive a first radiofrequency signal (SI) from said radar unit (11) and generate a corresponding second radiofrequency signal (S2) to be retransmitted toward said radar unit (11);

- a processing unit (14) connected to the radar unit (11) and configured to process said second radiofrequency signals (S2) and use them to reconstruct 2D or 3D

(two- or three- dimensional) radiofrequency images; the apparatus (10) being characterized in that said one or several transceiver elements (13) are configured to modify the received first radiofrequency signal (SI) to generate univocally identifiable second radiofrequency signals (S2) so as to create a one-to-one correspondence between the emitted second radiofrequency signals (S2) and the transceiver elements (13) of their emission, and in that the processing unit (14) is configured to know the spatial arrangement of said one or several transceiver elements (13) so as to create radiofrequency images based on the distribution pattern of said second radiofrequency signals (S2), which reflects said spatial arrangement of said one or several transceiver elements (13).

2. Apparatus (10) as in claim 1, characterized in that said one or several transceiver elements (13) comprise coding means (21) configured to generate said univocally identifiable second radiofrequency signals (S2) by generating an identification code through modulation of the received first radiofrequency signal (SI).

3. Apparatus (10) as in claim 1 or 2, characterized in that said processing unit (14) is configured to associate the characteristics of each second radiofrequency signal (S2) univocally identifiable by a corresponding transceiver element (13) with the color and/or intensity of a pixel of said radiofrequency images.

4. Apparatus (10) as in any one of the preceding claims, characterized in that said radar unit (11) comprises one or several transceiver elements, or one or several transmitting elements (16) and one or several receiving elements (17), wherein each of said elements can in turn consist of a single antenna or an array of antennas (18) and operate in any polarization.

5. Apparatus (10) as in claim 4, characterized in that said processing unit (14) is configured to know the spatial arrangement of said one or several transceiver elements or of said one or several transmitting elements (16) and one or several receiving elements (17) of said radar unit (11).

6. Apparatus (10) as in any one of the preceding claims, characterized in that said transceiver elements (13), when there are more than one, are positioned according to an arrangement chosen in a group consisting of: a linear onedimensional configuration, a flat two-dimensional array, a curved two-dimensional array or a scattered and not contiguous points.

7. Apparatus (10) as in any one of the preceding claims, characterized in that it comprises, or cooperates with, one or several vision devices selected from optical (50) and/or infrared (51) image detectors.

8. Apparatus (10) as in claim 7, characterized in that said processing unit (14) is configured to correlate said radiofrequency images with the optical and/or infrared images detected by said optical (50) and/or infrared (51) image detectors.

9. Method for creating radiofrequency images, comprising the steps of:

- sending, by means of a radar unit (11), a first radiofrequency signal (SI) toward a reflecting unit (12) comprising one or several transceiver elements (13), in a forward path;

- acquiring, by means of said one or several transceiver elements (13), said first radiofrequency signal (SI);

- generating, by means of said one or several transceiver elements (13), a relative second radiofrequency signal (S2); - further sending, in a return path, said second radiofrequency signals (S2) to said radar unit (11);

- further acquiring, by means of said radar unit (11), said second radiofrequency signals (S2);

- processing, by means of a processing unit (14) connected to the radar unit (11), said second radiofrequency signals (S2) in order to reconstruct 2D or 3D (two- or three- dimensional) radiofrequency images; the method being characterized by further comprising the following steps:

- modifying, by means of said one or several transceiver elements (13), the received first radiofrequency signal (SI) and generating univocally identifiable second radiofrequency signals (S2) so as to create a one-to-one correspondence between the emitted second radiofrequency signals (S2) and the transceiver elements (13) of their emission;

- communicating to the processing unit (14) the spatial arrangement of said one or several transceiver elements (13) so as to create radiofrequency images based on the distribution pattern of said second radiofrequency signals (S2), which reflects said spatial arrangement of said one or several transceiver elements (13).

10. Method as in claim 9, characterized in that it comprises the step of modulating, by means of coding means (21), said first radiofrequency signal (SI) in order to generate an identification code that univocally identifies said second radiofrequency signals (S2).

11. Method as in claim 9 or 10, characterized in that it comprises the step of positioning one or several objects (100) in a shooting space (SR) defined between said radar unit (11) and said reflecting unit (12) and illuminating said one or several objects (100) by means of said first radiofrequency signal (S 1) in the forward path, and by means of said univocally identifiable second radiofrequency signals (S2) in the return path.

12. Method as in any of the claims 9 to 11, characterized in that said steps of sending, acquiring, generating, further sending, further acquiring, processing, modifying and generating, communicating are repeated cyclically by a control unit (15) configured to control and command the operation of the apparatus (10) with a high frequency comprised in a range that goes from 1 GHz to 1 THz in order to make said apparatus (10) operate in real-time in order to create films or videos.

13. Use of an apparatus for creating radiofrequency images according to any one of claims 1 to 8 for creating 2D or 3D (two- or three- dimensional) radiofrequency images of objects (100) positioned in a shooting space (SR) defined between said radar unit (11) and said reflecting unit (12).

14. Use of an apparatus for creating radiofrequency images according to any one of claims 1 to 8 for calculating the distance of each of said transceiver elements

(13) of said reflecting unit (12) from said radar unit (11) after said processing unit

(14) has detected the images of a shooting space (SR) defined between said radar unit (11) and said reflecting unit (12).

15. Use of an apparatus for creating radiofrequency images according to any one of claims 1 to 8 for identifying an object (100) by reading a code (C) that is placed univocally associated to said object (100), wherein said code (C) comprises one or more parts (101) placed on an external surface of said object (100) or embedded therein, and wherein said code (C) is defined by the configuration, or by the geometrical arrangement, or by the permittivity of said one or more parts (101).