Device for measuring electromagnetic radiation of radiating object

Abstract

The invention relates to a device for measuring the electromagnetic radiation of a radiating object (10), comprising: a sealed box (20) containing the radiating object (10); a moving device (12) for moving the radiating object (10) in the longitudinal direction (L); a heat-sensitive film (14) housed in the tank (20); a camera (16) housed at a longitudinal end of the sealed box (20), opposite the radiating object (10) to be measured with respect to the heat-sensitive film (14), and designed to capture an image of the heat-sensitive film; and a processing device (18) for processing the image, the processing device being designed to provide an electromagnetic field pattern of the radiating object (10) picked up by the heat-sensitive film (4).

Description

Technical Field

[0001] The invention relates to an apparatus for measuring electromagnetic radiation of a radiating object, such as an antenna, in particular at radio or microwave frequencies. Background Art

[0002] It is often necessary to know the electromagnetic radiation of radiating objects, such as antennas, wireless phones, microwave transceivers, microwave equipment, inductive equipment, etc.

[0003] To this end, document WO 2020 / 0351193 proposes a device for measuring the performance capabilities of a radiating object in at least two different frequency bands. The device includes: an outer shell, forming an outer chamber provided with a radio frequency reflecting wall; an inner chamber, provided with a radio frequency absorbing wall, and the radiating object under test is accommodated in the inner chamber; a first test antenna arrangement, accommodated in the outer chamber, for measuring in a first frequency band; and a second test antenna arrangement, arranged inside the inner chamber, for measuring in a second frequency band.

[0004] Thus, the apparatus allows the performance capabilities of a radiating object to be measured by a first test antenna arrangement in a reflective radio frequency environment and allows the performance capabilities to be measured by a second test antenna arrangement in a substantially anechoic radio frequency environment.

[0005] This solution does not allow characterizing the electromagnetic radiation of an object radiating from an antenna, the solution only allows measuring the performance capabilities of a radiating object in a predetermined frequency band. Furthermore, the solution is complex to implement and requires the use of two sets of test antennas.

[0006] Therefore, the inventors have attempted to develop a simpler integrated device that allows characterizing a radiating object and reconstructing the radiation pattern. Summary of the invention

[0007] Purpose of the Invention

[0008] The present invention aims to provide an apparatus for measuring, characterizing and visualizing electromagnetic radiation of a radiating object.

[0009] The invention is particularly intended to provide a measuring device which allows measuring, characterizing and visualizing the radiation of an object at various frequencies.

[0010] The invention is particularly intended to provide a measuring device which does not require the use of complex components and has a limited number of components.

[0011] The invention aims in particular at providing such a measuring device which can be used by anyone without major problems and without requiring any specific technical knowledge of the operation of antennas.

[0012] In at least one embodiment, the present invention is also directed to a handheld device for measuring and characterizing electromagnetic radiation from a radiating object.

[0013] Disclosure of the Invention

[0014] To this end, the present invention relates to a device for measuring electromagnetic radiation of a radiating object, comprising:

[0015] - a sealed box, impermeable to electromagnetic radiation, extending in a longitudinal direction and provided with an opening suitable for allowing said radiating object to be measured to be accommodated in said box;

[0016] - modulation means for modulating the radiation of said radiating object.

[0017] The device according to the present invention is characterized in that the device also includes:

[0018] - moving means for moving said irradiating object in the longitudinal direction inside the sealed box between a position called the proximal position and a position called the distal position;

[0019] - a thermosensitive film, thermosensitive to electromagnetic fields, housed in said sealed box and extending in a plane perpendicular to said longitudinal direction near said proximal position;

[0020] - a camera housed at a longitudinal end of the sealed box, opposite to the radiation object to be measured relative to the thermosensitive film, and configured to acquire an image of the thermosensitive film, the thermosensitive film being arranged at a focal length from the camera;

[0021] - processing means for processing said images acquired by said camera, said processing means being configured to provide a map of the electromagnetic field picked up by said thermosensitive film.

[0022] Thus, the device according to the invention allows to measure the electromagnetic field of a radiating object and to provide a map. In particular, and according to the invention, the thermosensitive film is heated in contact with the electromagnetic radiation of the radiating object. This heating is imaged by a camera and then detected and characterized by an image processing device. The thermosensitive film can be sensitive to magnetic fields or electric fields. The thermosensitive film is arranged at a focal length from the camera.

[0023] The device according to the invention allows testing any type of radiating object that can be contained in a sealed box, thereby eliminating the need for anechoic chambers or mixing chambers using the solutions of the prior art. In particular, the device according to the invention allows obtaining images of the fields radiated by radiofrequency and / or microwave sources without any special precautions. Thus, such a device can be used in classrooms, design offices and generally in any room that is not specifically designed for electromagnetic radiation.

[0024] Throughout the text, and depending on the usage, radio waves (or Hertzian waves) are considered to mean electromagnetic waves having a frequency ranging between 3 Hz and 300 MHz, and microwaves are considered to mean electromagnetic waves having a frequency ranging between 300 MHz and 300 GHz.

[0025] The device according to the invention is an integrated device which does not require any external devices, except for an energy source for powering the radiation source, the camera, the image processing means and the means for longitudinally moving the irradiated object. According to an advantageous variant, the electrical energy source is formed by a rechargeable battery which is housed in a compartment adjacent to the sealed housing.

[0026] Furthermore, the device according to the invention has a particular feature that allows the radiating object to be longitudinally moved (for example using motorized means) relative to the thermosensitive film between a distal position, which is far from the thermosensitive film, and a proximal position, which is close to the thermosensitive film, which allows the electromagnetic radiation of the radiating object to be measured in different planes, which are located at different distances from the thermosensitive film. Thus, the device according to the invention allows the generation of a 3D reconstruction of the near-field amplitude by the image processing means.

[0027] Furthermore, and in the case of an antenna, amplitude measurements in two different planes allow algorithmic reconstruction of the phase of the field at any point of the antenna's aperture, thereby allowing reconstruction of the radiation pattern of this antenna.

[0028] According to an advantageous embodiment, the camera is equipped with an image acquisition sensor in the visible light domain and the device further comprises a monochromatic light source housed in said box and oriented towards the thermosensitive film so as to illuminate it, said film being coated with a layer of fluorescent material.

[0029] According to this alternative embodiment, the device is equipped with a camera equipped with a CCD or CMOS sensor in the visible light domain. The camera is provided with an optical filter adapted to the wavelength of the fluorescence emitted by the thermosensitive film covered with fluorophores. Furthermore, a light source housed in a box illuminates the thermosensitive film.

[0030] The fluorescent material must be a fluorophore that emits in the visible light region (approximately 400nm to 800nm) and has a fluorescence intensity that depends on temperature. According to one embodiment, the material used is Rhodamine B, which has a maximum fluorescence intensity of approximately 600nm at ambient temperature when subjected to light of a wavelength of 470nm, and experiences a significant decrease in this intensity (approximately 2% / °C) as the temperature of Rhodamine B increases. The difference between the wavelengths received by the excitation and fluorescence facilitates the measurement, since filtering on the camera will allow the reflection of the emitted light on the membrane to be eliminated without losing useful signal.

[0031] Of course, other materials that are both fluorescent and heat sensitive may be used without calling into question the principles of this advantageous embodiment.

[0032] According to a second embodiment, the camera is a camera equipped with an infrared sensor.

[0033] In this case, the camera directly captures the heating of the heat-sensitive film.

[0034] Regardless of the type of camera used (infrared or visible), the thermosensitive film used is either weakly conductive (for electric field measurements) or insulating and has magnetic losses (for magnetic field measurements). Therefore, under the influence of the electromagnetic field of the radiating object, the film heats up (usually in the range of 0.01°C to 10°C).

[0035] This heating is either directly recorded by the infrared camera (for the infrared version) or even causes a change in the fluorescence intensity that is recorded by a camera in the visible domain (for the fluorescence version).

[0036] Advantageously, the measuring device further comprises a filter arranged between the radiating object to be measured and the thermosensitive film, the filter being configured to filter components of the electromagnetic field in order to allow measurement of other components of the electromagnetic radiation of the radiating object to be measured.

[0037] Thus, and according to this advantageous variant, a filter is inserted between the radiating object and the thermosensitive film. For example, the filter is in the form of a second film, of the conductive grid or absorptive grid type or of a type having a specific pattern. The filter allows only the unfiltered component to pass through the thermosensitive film. Thus, for example, a cross-polarization measurement can be performed. In the case of circular polarization, the right / left property can also be obtained by means of a filter film using a suitable pattern, in particular a polarization selective surface (known by the abbreviation PSS).

[0038] According to an advantageous variant of the invention, the heat-sensitive membrane is detachably mounted inside the sealing box.

[0039] This variant allows the type of film to be changed easily and quickly. In particular, and according to the invention, the type of thermosensitive film used determines the type of field (electric or magnetic) that can be measured. For electric field measurements, weakly conductive films are used. For magnetic field measurements, insulating films with magnetic losses are used.

[0040] Such a removable assembly can be of any type. For example, the removable assembly can be a frame on which the membrane is placed, the frame being housed in guide rails facing each other on the inner wall of the box.

[0041] According to a particular embodiment of the invention, the thermosensitive film is an anisotropic film for determining the direction of the field and the spatial variation of the field or the ellipticity of the field as a function of the polarization of the field radiated by said object to be measured.

[0042] According to this advantageous variant, the anisotropic film comprises an array of patterns for determining the spatial variation of the amplitude and direction of the field radiated by said radiating object (for linear polarization), or even of the amplitude and ellipticity of said field (for circular polarization).

[0043] Such anisotropic films are films with a specific pattern (parallel strips, stars with three or more branches) that, in addition to the amplitude, allow the polarization of the electric field to be determined, including the ellipticity in the case of circular polarization. Using such an array of patterns, it is also possible to determine the spatial distribution of these amplitudes and polarizations in the plane.

[0044] According to a variant of the invention, said modulation means for modulating the radiation of said radiating object comprise a microcontroller, a synthesizer and a radiofrequency or microwave amplifier, the microcontroller, the synthesizer and the radiofrequency or microwave amplifier being housed in a dedicated compartment.

[0045] This variant allows radiating objects to be powered and controlled.

[0046] According to another variant of the invention, the modulation means for modulating the radiation of the radiating object comprises:

[0047] - a baffle screen arranged between the radiating object and the thermosensitive film, the baffle screen being configured to be able to switch from a state called a transparent state, in which the radiation of the radiating object can reach the thermosensitive film, to a state called an opaque state, in which the screen prevents the radiation from the radiating object from reaching the thermosensitive film;

[0048] - control electronics configured to control the barrier screen between an opaque state and a transparent state and configured to control the barrier screen between a transparent state and an opaque state.

[0049] This variant allows the measurement of the field of non-cooperative objects. The shutter screen placed in front of the thermosensitive film ensures a low-frequency modulation of the object by opening and closing at a frequency of a few tenths of Hz to a few Hz as mentioned above. The shutter can be realized by electrical or mechanical means. For example, a mechanical shutter consists of two parallel gates, each of which shields 50% of the thermosensitive film, one of which oscillates laterally over a distance equal to the step length of the gates, allowing 50% opening (superimposed gates) or closing (gate offset by one step length). The electric shutter can be a liquid crystal film or a plasma film (the intermittent activation of the liquid crystal film or plasma film ensures the alternation of opacity / transparency).

[0050] Advantageously, the moving device for moving the radiation object in the longitudinal direction comprises a track, the radiation object being able to slide along the track, and a motor for moving the object on the track.

[0051] Other means for moving the irradiating object between the proximal and distal locations may be implemented without changing the subject matter and results of the present invention.

[0052] In addition to the means for longitudinally moving the object, provision can also be made to provide the device with means for pivoting the radiating object on itself in order to modify the angular aperture of the field measurement.

[0053] Advantageously, and according to the invention, the sealed box opaque to electromagnetic radiation is formed by a box having an inner wall covered with a microwave absorbent.

[0054] These absorbers are configured to prevent any reflection of the electromagnetic field and to attenuate the emission of the field towards the outside of the sealed box.

[0055] The invention also relates to a measuring device, characterized by all or some of the features mentioned above or below. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Further objects, features and advantages of the present invention will become apparent on reading the following description which is given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0057] Figure 1 is a schematic perspective view of a measuring device according to one embodiment of the present invention, the measuring device being equipped with an infrared camera, the view also comprising a cross-sectional view for viewing elements present in the measuring device;

[0058] Figure 2 yes Figure 1 A schematic perspective view of a device in which a radiating object has been moved relative to a heat-sensitive film;

[0059] Figure 3 is a schematic perspective view of a measuring device according to another embodiment of the invention, the measuring device being equipped with a camera in the visible light domain and being equipped with a source for emitting fluorescent light, the view also comprising a sectional view for viewing elements present in the measuring device;

[0060] Figure 4 yes Figure 3 A schematic perspective view of a device in which a radiating object has been moved relative to a heat-sensitive film;

[0061] Figure 5is a schematic perspective view of a measuring device according to another embodiment of the invention, the measuring device being equipped with an additional filter arranged between the radiating object and the heat-sensitive film, the view also comprising a cross-sectional view for viewing the elements present in the measuring device;

[0062] Figure 6 is a schematic perspective view of a measuring device according to one embodiment of the invention, showing the cover of the device in an open position, the view also comprising a cross-sectional view for viewing the elements present in the measuring device. DETAILED DESCRIPTION

[0063] In the drawings, for the sake of illustration and clarity, no strict adherence to dimensions and proportions is made. Throughout the detailed description below with reference to the drawings, unless otherwise specified, each element of the measuring device is described as being arranged when the radiating object is housed in a sealed box of the measuring device. In particular, Figure 1 This configuration is shown in .

[0064] Furthermore, in all figures, identical, similar or like elements are denoted by the same reference numerals. Figure 1 As shown, the terms longitudinal, transverse and vertical are used in a non-limiting manner with reference to the L, T, V trihedron. The longitudinal direction corresponds to the main direction of the measuring device, along which the radiating object can move. The vertical direction is the direction defined by gravity. The transverse direction is the direction perpendicular to the longitudinal direction and the vertical direction.

[0065] Figure 1 and Figure 2 A device for measuring electromagnetic radiation of a radiating object 10, such as an antenna, according to a first embodiment is shown.

[0066] According to this embodiment, the device comprises a sealed box 20, which is formed by Figure 6 The lower box 20a and the cover 20b shown in FIG. 2 are formed, and the cover 20b is hingedly mounted on the lower box 20a.

[0067] The irradiation object 10 is mounted on a sliding rail 12 which forms a means for moving the irradiation object 10 in a longitudinal direction L.

[0068] The irradiation object 10 may be arranged along the longitudinal direction L. Figure 1 and Figure 3 The position referred to as the proximal position schematically shown in FIG. Figure 2 and Figure 4 Movement between positions referred to as distal positions shown schematically in FIG.

[0069] This movement may be obtained by motorized means (not shown), such as an electric motor driving the irradiation object 10 along the track 12 .

[0070] The measuring device also comprises modulation means 13 for modulating the radiation of the radiating object. These modulation means are housed in a specific compartment 15 arranged at a first longitudinal end of the sealed box 20, for example.

[0071] The measuring device further comprises a thermosensitive membrane 14 which is thermosensitive to electromagnetic fields, is housed in a sealed box 20 and extends transversely near a proximal position, ie the thermosensitive membrane 14 extends in a plane perpendicular to said longitudinal direction.

[0072] The measuring device further includes a camera 16 which is accommodated at a second longitudinal end of the sealed box 20 , opposite to the radiation object 10 to be measured with respect to the thermosensitive film 14 .

[0073] Finally, the measuring device comprises a computer 18 forming means for processing the images acquired by the camera 16 . This computer 18 comprises a software routine configured to provide a map of the electromagnetic field picked up by the thermosensitive film 14 .

[0074] exist Figure 1 and Figure 2 In the embodiment of FIG. 1 , the camera 16 is an infrared camera configured to directly capture the heating of the heat-sensitive film.

[0075] exist Figure 3 and Figure 4 In the embodiment of the invention, the camera 16 is a camera in the visible light domain, and the camera is configured to be able to capture fluorescence emitted by the thermosensitive film 14 covered with fluorophores. To this end, the device further comprises a light source 17, which illuminates the thermosensitive film 14. In this case, the camera 16 is provided with an optical filter, which is suitable for the wavelength of fluorescence emitted by the thermosensitive film covered with fluorophores. The material covering the thermosensitive film may be Rhodamine B, for example, when Rhodamine B is subjected to light with a wavelength of 470 nm, the maximum fluorescence intensity of Rhodamine B is about 600 nm at ambient temperature.

[0076] Whatever the embodiment, the principle of the invention is based on the interaction of the film 14 with the field radiated by the radiating object 10 .

[0077] The thermosensitive film 14 is either weakly conductive (for electric field measurements) or insulating and has magnetic losses (for magnetic field measurements). Therefore, under the action of the field, the film heats up (typically in the range of 0.01°C to 10°C). This heating is recorded directly by the infrared camera (for Figure 1 and Figure 2), or even cause a change in the fluorescence intensity recorded by the camera 16 (for Figure 3 and Figure 4 of the embodiment of the invention).

[0078] The radiation of the radiating object 10 heats the membrane 14 (the membrane 14 is a thin film, i.e. of very limited thickness and wavelength compared to the thickness of the skin: the field and the temperature are assumed to be constant in the thickness of the membrane) in proportion to the absorbed power density according to the following formula:

[0079]

[0080] Wherein, e represents the thickness of the membrane 14, and h is the convection coefficient. The absorbed power density is provided by the following equation:

[0081]

[0082] Here, f represents the frequency of the radiation, σ represents the electrical conductivity of the film 14 , ε″ represents the permittivity (imaginary component) of the film 14 , and μ″ represents the magnetic permeability (imaginary component) of the film 14 .

[0083] For electric field measurements, the measuring device is equipped with a "lossy" membrane, ie with low permittivity and negligible magnetic permeability, but with non-zero conductivity. Thus, only the first component of the aforementioned equation is considered, and the power is proportional to the square of the electric field.

[0084] For magnetic field measurements, the measuring device is equipped with a "lossy" membrane, ie with high magnetic permeability, but with negligible electrical conductivity and permittivity. Therefore, only the second component of the aforementioned equation is considered, and the power is proportional to the square of the magnetic field.

[0085] Therefore, for Figure 1 and Figure 2 In an embodiment of the invention (infrared camera), the computer 18 comprises a software routine configured to reconstruct the amplitude map of the field (electric or magnetic) in the plane (Oxy) of the membrane from the thermal image acquired by the camera 16 according to the square root of the heating and using a proportionality factor k that depends only on the membrane. The software means is programmed to calculate the following amplitude:

[0086] - For membranes with electrical losses,

[0087] -For films with magnetic losses,

[0088] for Figure 3 and Figure 4In the embodiment of the invention (visible light and fluorescence camera), the image processing device 18 is configured to reconstruct the amplitude map of the field (electric or magnetic field) in the plane (Oxy) of the membrane from the optical image captured by the camera 16 according to the square root of the fluorescence intensity (signal received by the camera) and using the coefficient g. Generally, fluorescence decreases with temperature; in the absence of field ("cold"), fluorescence produces an intensity I 0 , so the intensity I 0 The field (by means of the field-induced temperature change of the film) reduces I fluo For example, the processing means 18 comprises software means programmed to calculate the amplitude:

[0089] - For membranes with electrical losses, -For films with magnetic losses,

[0090] As indicated above, the thermosensitive membrane 14 depends on the type of measurement to be performed. The membrane is preferably removably mounted in the sealed box 20 so as to be able to be easily positioned / replaced depending on the type of measurement to be performed.

[0091] In order to measure the amplitude of the electric field (E) of the radiating object 10, a weakly conductive film 14 is used, which consists of a composite material based on an electrically insulating matrix and conductive particles. The conductive particle filler must be adjusted so that the absorptive material has a "low" surface impedance (= resistivity / thickness), i.e., the surface impedance ranges between 500Ω and 3000Ω, so that the absorptive material absorbs only a part of the electric field. The surface impedance is adjusted depending on the concentration of particles in the insulating matrix and on the thickness of the absorptive material layer. Carbon-filled polyimide (Kapton) with a thickness of several tens of micrometers is an example of a film that can be used.

[0092] For magnetic field measurement, composite materials based on electrically insulating matrix and magnetic particles are used. The density of ferromagnetic particles must be kept low enough to limit absorption and therefore the interference provided on the field intended to be measured. In practice, polymer matrix films containing iron particles (volume fraction of 10% to 20%) are fully usable. It is also conceivable that a solution containing magnetic nanoparticles is deposited onto a neutral film (electrically and magnetically) thereon, which has a concentration and thickness suitable for measurement.

[0093] The measuring device also preferably comprises a compartment 15 housing modulation means 13 for modulating the radiation of the radiating object.

[0094] These modulation means depend on the type of radiating object whose radiation is intended to be measured.

[0095] In particular, the measuring device according to the invention can have a transient mode and a low-frequency modulation mode.

[0096] Directly recording images allows electromagnetic interpretation and field transcription within the context of fast transient phenomena (without implementing complex thermal phenomena such as conduction, convection, etc.).

[0097] Within the context of a direct harmonic electrical supply (CW) of the source, which is the standard mode of the source if it is an antenna, for example, a low-frequency modulation of the source (from a few tenths of a Hertz to a few Hertz) associated with filtering of the recorded image (synchronous detection) allows to eliminate the above-mentioned thermal phenomena, namely conduction in the film and convection with the ambient air. In addition, this synchronous demodulation allows to improve the signal-to-noise ratio and the measurement dynamics. In fact, the thickness of the film is of the order of a hundred microns or less. Using the typical characteristics of Kapton (measurement of E) or even using the typical characteristics of polymer matrix films (measurement of H), the thermal time constant τ of the film is a few seconds, provided by the following formula:

[0098]

[0099] Where C corresponds to the heat capacity (in J / kg / K), and ρ is the density (in kg / m 3 ), h is the convection coefficient (unit: W / m 2 / K), and e is the thickness of the film in m.

[0100] Convective equilibrium is reached within a few seconds (the membrane according to (1-e -t / τ ) increases the temperature and stabilizes according to the exponential law in the LF modulation, but the LF modulation does not give it time to do so. Therefore, the increase in temperature is slowed down and linearized (e.g., a square all-or-nothing modulation for the source is triangular).

[0101] Thus, the modulation system is arranged to apply a modulation time sequence of the electromagnetic radiation to which the membrane is exposed. The synchronous detection system is arranged to filter the intensities captured in the successive images of the surface of the membrane according to the modulation time sequence. This can be performed during the measurement or even after the recording is completed, for example, by means of a Fast Fourier Transform (FFT).

[0102] In the case where the radiation source cannot be controlled, a shutter (mechanical or electrical) placed in front of the sensor membrane and controlled to open / close allows to recreate the modulation (for all or nothing), which allows to measure and correspond to the previous situation by synchronous detection. For example, a mechanical shutter can be formed by two parallel gates, each shielding 50% of the membrane, one of which oscillates laterally over a distance equal to the step length of the gates, allowing 50% to be open (superimposed gates) or closed (gates offset by one step length). The electrical shutter can be a liquid crystal membrane or a plasma membrane (intermittent activation of the liquid crystal membrane or plasma membrane ensures the alternation of opacity / transparency).

[0103] The device according to the invention allows the irradiation object 10 to be moved along a longitudinal track 12 .

[0104] The device according to the invention thus allows measuring the electromagnetic radiation of the radiating object 10 in different planes, the different planes being located at different distances from the thermosensitive film 14. The device according to the invention thus allows the image processing means 18 to produce a 3D reconstruction of the near field amplitude.

[0105] In particular, in the case of an antenna, amplitude measurements in two different planes allow obtaining the phase of the field at any point of the antenna's aperture and therefore reconstructing the radiation pattern of the antenna. To this end, the image processing device can implement a method known as "planar near-field / far-field phase retrieval" using software means.

[0106] Figure 5 An alternative embodiment of a measuring device is shown in which a filter 19 is arranged between the radiating object 10 to be measured and the thermosensitive film 14. The filter is configured to filter a component of the electromagnetic field in order to allow the measurement of other components of the electromagnetic radiation of the object to be measured. For example, the filter 19 is formed by a film of the conductive grid or absorptive grid type or a film of the type with a specific pattern, in particular a polarization selective surface (PSS). The filter 19 allows only the unfiltered component to pass through the thermosensitive film 14.

Claims

1. A device for measuring electromagnetic radiation of a radiating object (10), comprising: - a sealed box (20), impermeable to electromagnetic radiation, extending in a longitudinal direction (L) and provided with an opening suitable for allowing the radiating object (10) to be measured to be housed in the box; - modulation means (13) for modulating the radiation of the radiating object; Characterized in that the device also includes: - moving means (12) for moving the irradiating object (10) inside the sealed box (20) along the longitudinal direction (L) between a position called the proximal position and a position called the distal position; a thermosensitive film (14), thermosensitive to electromagnetic fields, housed in said sealed box (20) and extending in a plane perpendicular to said longitudinal direction near said proximal position; a camera (16) housed at a longitudinal end of the sealed box (20), opposite to the radiation object (10) to be measured relative to the thermosensitive film (14), and configured to acquire an image of the thermosensitive film, the thermosensitive film (14) being arranged at a focal length from the camera (16); - processing means (18) for processing the image acquired by the camera (16), the processing means being configured to provide a map of the electromagnetic field of the radiating object (10) picked up by the thermosensitive film (4).

2. The device according to claim 1, characterized in that The camera (16) is equipped with an image acquisition sensor in the visible light domain, the device further comprises a monochromatic light source (17) oriented to illuminate the thermosensitive film (14), and the film is coated with a layer of fluorescent material.

3. The device according to claim 1, characterized in that The camera (16) is a camera equipped with an infrared sensor.

4. The device according to any one of claims 1 to 3, characterized in that The modulation means (13) for modulating the radiation of the radiating object (10) comprises a microcontroller, a synthesizer and a radio frequency or microwave amplifier, the controller, the synthesizer and the radio frequency or microwave amplifier being housed in a dedicated compartment (15).

5. The device according to any one of claims 1 to 3, characterized in that The modulation means (13) for modulating the radiation of the radiating object comprises: - a baffle screen arranged between the radiating object (10) and the thermosensitive film (14), the baffle screen being configured to be able to switch from a state called a transparent state, in which the radiation of the radiating object can reach the thermosensitive film, to a state called an opaque state, in which the screen prevents the radiation from the radiating object from reaching the thermosensitive film; - control electronics configured to control the barrier screen between the opaque state and the transparent state and configured to control the barrier screen between the transparent state and the opaque state.

6. The device according to any one of claims 1 to 5, characterized in that The device further comprises a filter (19) which is arranged between the radiating object (10) to be measured and the thermosensitive film (14), the filter (19) being configured to filter components of the electromagnetic field so as to allow measurement of other components of the electromagnetic radiation of the radiating object (10) to be measured.

7. The device according to any one of claims 1 to 6, characterized in that The thermosensitive film (14) is an anisotropic film comprising an array of patterns for determining the spatial variation of the amplitude and direction of the field radiated by the radiating object (10) (for linear polarization), or even the spatial variation of the amplitude and ellipticity of the field radiated by the radiating object (10) (for circular polarization).

8. The device according to any one of claims 1 to 7, characterized in that The heat-sensitive film (14) is detachably installed inside the sealing box (20).

9. The device according to any one of claims 1 to 8, characterized in that The moving device (12) for moving the radiation object (10) along the longitudinal direction (L) comprises a track along which the radiation object (10) can slide, and a motor for moving the object on the track.

10. The device according to any one of claims 1 to 9, characterized in that The sealed box (20) opaque to the electromagnetic radiation is formed by a box having an inner wall which is covered with a microwave absorbent.

Images