Patch antenna comprising an element for covering the skin of a user

Abstract

The invention relates to a patch antenna (28) for near field radiation. The patch antenna comprises an element (52) having a surface intended to cover the skin of a user. Furthermore, the element (52) intended to cover the skin is arranged such that the impedance of the antenna (28) matches the impedance of the skin.

Description

Technical Field

[0001] The present invention relates to radiating electromagnetic waves toward human subjects, and in particular to a patch antenna for millimeter wave near-field radiation. Background Art

[0002] From the prior art according to patent application FR 1 758 634 in the name of the present applicant, a patch antenna is known which comprises an array of patches and is capable of transmitting power at a power of more than 0.5 mW / cm 2 The antenna is powered by application-specific integrated circuits (ASICs) within the device to radiate millimeter waves toward the skin for therapeutic purposes, particularly for the treatment of chronic pain.

[0003] However, the antenna's efficiency—the ratio between the wave transmission to the skin and the power delivered by the ASIC—is low. Furthermore, the test protocol is designed for antennas that radiate into the air, not the skin. Consequently, the antenna presents challenges in terms of testability. Summary of the Invention

[0004] One object of the present invention is, inter alia, to improve antenna efficiency. Another object is to improve the testability of the antenna.

[0005] To this end, according to the present invention, there is provided a patch antenna for near-field radiation comprising an element intended to cover the surface of a user's skin, the element being arranged such that the impedance of the antenna matches the impedance of the skin.

[0006] The term "antenna" refers to an antenna network, radiating patch, or more generally, any component or group of components directly involved in emitting radiation. Without a component intended to cover the skin, the antenna is suitable for transmitting electromagnetic radiation outward into the air and can be tested using traditional protocols. With the component, it acts as an impedance converter, adapting the antenna's impedance to the user's skin, thereby avoiding transmission losses and significantly improving the antenna's efficiency in radiating radiation to the skin. This improves antenna performance and testability.

[0007] Preferably, when electromagnetic waves pass through the element at a frequency of 61.25 GHz, the intrinsic impedance value of the element is between the intrinsic impedance value of air and the intrinsic impedance value of dry skin, the latter being derived from the complex dielectric constant of dry skin of 8-j11 ohms.

[0008] Impedance transformation is achieved by designing the element so that its inherent impedance lies between the impedance of air and the impedance of dry skin. Thus, the impedance of the element mediates between the impedance of the air in which the antenna without the element is located and the impedance of the skin to which the antenna radiates through the element.

[0009] Advantageously, said element comprises a biocompatible material.

[0010] Thereby, the element is adapted to be in tolerable contact with the user's skin.

[0011] Preferably, the element comprises only polycarbonate, and the thickness of the element is between 0.5 mm and 3 mm, preferably 0.6 mm, or 0.6 mm plus an integer multiple of half the wavelength of an electromagnetic wave when passing through the element.

[0012] The thickness of the element is thereby set so that the impedance of the element is as suitable as possible while the element takes up a minimum of space.

[0013] Advantageously, said element comprises a dielectric constant less than or equal to 4, and a dissipation factor less than or equal to 0.2.

[0014] These are the ranges of values ​​relating to the impedance of the element such that it fully fulfils its role as an impedance adapter between the antenna and the skin.

[0015] Preferably, the antenna comprises a width equal to or less than 10 cm 2 The main area value of .

[0016] As a result, the antenna is particularly small and can therefore be easily integrated into an electromagnetic radiation transmission module.

[0017] Advantageously, the antenna comprises at least eight patch devices for radiating electromagnetic waves, these devices being located on the same substrate and separated from each other by a distance value of 2.4 to 2.5 mm, and these eight devices being able to be exposed to 0.625 cm 2 Up to 1cm 2 Electromagnetic radiation of a continuous area.

[0018] Thus, the patch devices serve as the antenna's radiating elements. In other words, the antenna is a network of antennas, with each patch considered an integral antenna of the network. The patches are arranged so that the antenna network exposes a continuous area to radiation. The distance between the patch devices corresponds to half the wavelength of a wave emitted into empty space at approximately 60 GHz, further improving the antenna's efficiency and the uniformity of its radiation.

[0019] Preferably, in order to improve the uniformity of radiation, the patch device is configured to radiate in phase.

[0020] Advantageously, the antenna comprises a printed circuit board having a substrate having a dielectric constant value of 2.9 to 3.1, a dissipation factor value of 0.0010 to 0.0020, a layer thickness of 0.1 to 0.6 mm, preferably 0.2 to 0.3 mm, when electromagnetic waves pass through the element at a frequency of 61.25 GHz, and a total substrate assembly thickness of between 0.5 and 1.6 mm.

[0021] These features improve the efficiency of the radiation emitted by the antenna.

[0022] Preferably, the antenna comprises via fences at all edges of the substrate, the vias of the fences having a diameter greater than or equal to 175 microns and a spacing between the vias greater than or equal to 300 microns.

[0023] As a result, the number of required through-holes is reduced compared to the number of through-holes that would be required if the through-holes were smaller, thereby reducing production costs.

[0024] Advantageously, the cavity formed by the through-hole fence is arranged such that the resonance frequency of the cavity has a value outside the frequency range from 55 to 65 GHz.

[0025] Thereby, the emitted waves are not disturbed by the cavity.To achieve this arrangement, the positioning of the through-holes can be adjusted.

[0026] Furthermore, according to the previously mentioned patent application FR 1 758 634 in the name of the present applicant, a wristband capable of emitting millimeter waves is known, which comprises a power greater than 0.5 mW / cm2 at the patient's wrist. 2 The wristband is designed to provide a surface power density of 100 nm, specifically for treating chronic pain in patients. The wristband includes a wave transmission module, which comprises four application-specific integrated circuits (ASICs) dedicated to generating millimeter-wave radiation. Each of these circuits feeds radiation to four planar antennas. These antennas allow for a continuous 2.5 cm wave exposure of the patient's wrist skin surface. The dimensions of the module integrated into the wristband are 37 mm in length, 20 mm in width, and 3 mm in thickness.

[0027] However, due to these dimensions, the rigid module integrated into the bracelet cannot optimally conform to the shape of the patient's wrist, resulting in an air gap between the skin and the bracelet, reducing the efficiency of the antenna radiation. Moreover, these dimensions make its mechanical integration into the bracelet difficult.

[0028] Therefore, another object of the invention is to improve the efficiency of the radiation emitted by the module.Another object of the invention is to facilitate the mechanical integration of the module in a device, in particular in a bracelet.

[0029] Therefore, the present invention also provides an electromagnetic wave transmission module, which has a total volume of less than 1 cubic centimeter and includes at least one electromagnetic wave radiation source connected to at least one transmitting antenna, which is capable of transmitting electromagnetic waves with a power density of at least 0.5 milliwatts per square centimeter of area when the module is arranged at a surface.

[0030] As a result, the module is particularly small, making it easier to integrate into portable devices. Furthermore, its small size allows it to optimally adapt to the nearly round shape of a patient's skin, such as the circumference of a wrist or ankle, thereby improving the efficiency of the emission. Finally, by using a single emission source instead of four, the module's manufacturing costs are reduced.

[0031] Advantageously, said surface is the skin and said transmitting antenna comprises an element having a surface intended to cover the skin.

[0032] Thus, this small volume also includes the presence of the protective element of the antenna, which is intended to achieve the link between the antenna and the skin and which can be called a radome. It is placed between the transmitting antenna and the surface to which the waves are transmitted.

[0033] Preferably, the power density of the wave has a value between 5 and 35 milliwatts per square centimeter.

[0034] This is a particularly effective power band for treating chronic pain in patients with millimeter waves. In addition, legal standards require limiting the power density of the waves so that the module can be controlled if necessary so as not to exceed a given threshold.

[0035] Advantageously, the frequency of said waves has a value between 3 and 120 GHz, preferably between 55 and 65 GHz.

[0036] This is a frequency band that is particularly effective for treatment with millimeter waves.

[0037] Preferably, the radiation source is an application specific integrated circuit (ASIC) having a total volume value of less than 5 cubic millimeters and capable of generating radiation emitted by the transmitting antenna when powered.

[0038] As a result, the radiation source has particularly small dimensions while being able to generate radiation with suitable properties.

[0039] Advantageously, the transmitting antenna comprises a planar antenna or a planar antenna network, the main area of ​​which is 0.5 to 2 cm 2 , the planar antenna or planar antenna network being capable of emitting said radiation towards said surface when it is energized by radiation generated by said radiation source.

[0040] The antenna thus has particularly small dimensions, making it easy to integrate it into a module while optimally exposing the patient's skin to the waves emitted by it. Its miniaturization makes it possible to avoid the creation of air gaps between the antenna and the patient's skin, even on a nearly round part of the patient's wrist, for example.

[0041] Preferably, the radiation source is connected to at least four different transmitting antennas.

[0042] The four antennas can in particular be four patch devices or planar devices that can radiate waves. Thus, the power of the source is sufficient to power the four planar antennas alone.

[0043] Advantageously, the radiation source is connected to eight different transmitting antennas.

[0044] The power of this source is therefore sufficient to power all eight antennas on its own. This further reduces the manufacturing cost of the module compared to a module with one radiation source for four transmitting antennas, and therefore two sources for eight antennas. This also facilitates the mechanical integration of the module, as there is a single source for eight antennas, rather than two sources, saving space.

[0045] Preferably, the module comprises two respective radiation sources each connected to eight respective transmitting antennas.

[0046] The antennas are thus divided into two groups of eight antennas each, each with its own radiation source. This arrangement allows the benefits of modularity to be achieved, as each group can be assembled separately before being integrated into the transmission module.

[0047] Advantageously, at least some of the antennas form a network of antennas connected to each other.

[0048] This simplifies powering the antennas, as the antennas of the network are interconnected. A radiation source can thus be connected to the circuit at a single point to power all antennas in the network. In particular, a network can be formed with eight separate antennas, allowing a single ASIC to power the entire network. Thus, the module comprises two ASICs and two separate networks.

[0049] Preferably, the module includes:

[0050] - a frequency generator capable of generating a reference frequency;

[0051] - a frequency measuring device capable of measuring a frequency derived from the frequency of the radiation emitted by the radiation source; and

[0052] - A frequency comparator capable of comparing the derived frequency with a reference frequency.

[0053] This allows verification of whether the frequency of the radiation corresponds to the selected radiation frequency. In practice, since the radiation and its frequency are generated within the radiation source and lack an absolute frequency reference, such as with quartz, the frequency of the radiation is subject to manufacturing tolerances and temperature variations. Therefore, a much lower reference frequency is generated outside the radiation source and compared with the also much lower frequency derived from the radiation frequency to verify that the radiation frequency is the selected one. In other words, measuring the frequency derived from the radiation frequency allows verification of whether the radiation frequency is the correct one.

[0054] According to the present invention, there is also provided a portable device for transmitting electromagnetic waves, which comprises at least two modules as described above and a power source for supplying power to the modules.

[0055] Thus, the portable device allows the emission of waves to the patient's skin without physical limitations, and the patient can use it at home, outdoors, on the move, etc. The presence of two small modules, rather than a single larger module, facilitates the mechanical integration of the modules and improves radiation efficiency. In fact, on a nearly circular part of the wrist, for example, two small modules that are different from each other, or even separated from each other, will better adapt to the shape of the skin compared to a single larger rigid module. This approach of dividing the module into two separate smaller modules thus makes it possible to reduce or even avoid the formation of an air gap between the module and the patient's skin, while maintaining the same exposed area as a single module and having the same electromagnetic wave radiation characteristics.

[0056] Advantageously, the modules are arranged to expose non-adjacent respective areas of the surface to the electromagnetic waves.

[0057] Thus, unlike a single module exposing a continuous surface to the waves, dividing the module into two smaller modules makes it possible to expose different areas of the surface, even though the value of the total area exposed to the waves remains constant.

[0058] Preferably, the apparatus is capable of simultaneously exposing a total of at least 1 square centimeter of surface, preferably at least 2.5 square centimeters of surface, to the waves.

[0059] Thus, even though each module is smaller, the total surface area exposed to the two modules is at least equal to 2.5 square centimeters, which is sufficient to achieve therapeutic effects in treating chronic pain. However, one of the two modules can be deactivated, and the therapeutic effect can still be maintained by emitting waves from a single module, i.e., for an exposed area of ​​1.25 square centimeters or even 1 square centimeter.

[0060] Advantageously, each module is electrically connected to the power supply by a respective flexible electrical connection means.

[0061] Thus, the flexible nature of the connection allows the modules to be placed in a wider range of positions than if the connection were rigid. In particular, each module can be placed close to a different area of ​​the human wrist. In other words, the flexibility of the connection enables the modules to be positioned independently of each other, whereas a rigid connection would impose much greater placement (positioning) constraints.

[0062] Preferably, the device comprises a control module for controlling these modules, the control module being different from the power supply and each transmission module, the control module being electrically connected to the power supply and each transmission module via respective flexible electrical connection means.

[0063] Thus, the control module capable of controlling the transmission modules is distinguishable from these transmission modules. Here again, the flexible nature of the connection device facilitates the integration of all components in the portable device. In particular, this enables these components to be arranged independently of each other, which would not be possible with a rigid connection device.

[0064] Advantageously, at least some of said flexible electrical connection means are flexible printed circuits.

[0065] Thereby, the mechanical integration of the components is further facilitated.

[0066] Preferably, the device comprises a flexible wristband, and the transmitting module is arranged in the flexible wristband to expose different parts of the wrist surface to the waves.

[0067] Thus, the transmitting modules are distributed in the flexible part of the bracelet to avoid the formation of an air gap between each transmitting module and the wrist, thereby improving radiation efficiency.

[0068] Advantageously, the device is capable of being worn at at least one of the following locations:

[0069] - On the face;

[0070] - around the wrist;

[0071] - on one leg;

[0072] - around the ankle;

[0073] - on the back;

[0074] - one ear; or

[0075] -In the palm of one hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The invention will be better understood by reading the description made and given by way of example with reference to the accompanying drawings, in which:

[0077] - Figure 1is an overall overview of a system according to one embodiment of the present invention;

[0078] - Figure 2 is a schematic diagram of the elements of this embodiment;

[0079] - Figure 3 is a perspective view of the device according to this embodiment;

[0080] - Figure 4 is an illustration of the front portion of the wave launch module of this embodiment;

[0081] - Figure 5 This is a diagram of the back of the module;

[0082] - Figure 6 This is an overview of the module;

[0083] - Figure 7 is an overview of the module’s circuit-antenna pair;

[0084] - Figure 8 Here is a schematic diagram of the circuit for the pair;

[0085] - Figure 9 is a schematic diagram of a patient's hand using the present invention;

[0086] - Figure 10 is a diagram of modules connected together according to one embodiment of the present invention;

[0087] - Figure 11 is a general diagram of these connections;

[0088] - Figure 12 is a schematic diagram of a wave transmission module according to one embodiment of the present invention;

[0089] - Figure 13 is a schematic diagram of a radiating patch according to one embodiment of the present invention; and

[0090] - Figure 14 is a general diagram of the distribution of an antenna network according to the present invention. DETAILED DESCRIPTION

[0091] First, an embodiment and implementation of an electromagnetic wave transmission module will be described. Next, an embodiment of an antenna included in the module for transmitting electromagnetic radiation will be described. This antenna is particularly well-suited for the described transmission module, but it can also be integrated into other devices and thus not inherently linked to the module.

[0092] I. emission Module

[0093] A-Component

[0094] Figure 1The overall framework of the present invention is shown. Patient 1 suffers from chronic pain. He wears device 10 according to the first embodiment and first implementation of the present invention. The device treats the pain by emitting electromagnetic millimeter waves to the skin at the wrist of patient 1. "Millimeter waves" refer to electromagnetic waves with a frequency of 30 to 300 GHz, but the scope of application of the present invention can also be extended to waves with a frequency of 3 to 30 GHz.

[0095] In this case, the device 10 has the general shape of a wristwatch or bracelet and is fastened around the wrist in the same manner as a watch. Figure 2 This is schematically shown in Figure 3 The device 10, shown in more detail in FIG, comprises a control or command module 20 and two wave emission modules 22, 24. The device 10 has the overall shape of a watch and may be a watch in which the modules 20, 22 and 24 are integrated. Conversely, the functionality of a watch may be integrated into the device 10.

[0096] Control module 20 controls transmission modules 22 and 24. Control module 20 is activated by the patient, but it can also be programmed by the patient or another user directly on device 10 via button 23 or via a terminal such as computer 12. Button 23 is provided with a light-emitting diode that can be activated to indicate an event to the patient, such as a low battery or the ongoing operation of a specific procedure. Control module 20 resides in the upper portion of device 10, while millimeter-wave transmission modules 22 and 24 are located in the lower portion, intended to contact the skin on the lower part of the wrist.

[0097] The electromagnetic wave transmission module 22 integrated into the device 10 will now be described in detail. Unless otherwise specified, the features of the module 24 are identical, so the following description of the module 22 also applies to the module 24. This module can be integrated into any type of device designed to transmit waves, not just the wristwatch-shaped device 10. Its applications are not limited to pain treatment.

[0098] exist Figure 4 and 5 and its content components are shown in Figures 6 to 8 The transmission module 22, shown schematically in FIG, has two circuits—antenna pair 42, heat sink 46, and skin sensor 44. It also has (but not shown) a power input, digital controls, a reference clock, and a temperature sensor 49. However, the same module 24 can have fewer components. Thus, the skin sensor and temperature sensor can be present in only one of the two modules.

[0099] Each of the two circuit-antenna pairs 42 comprises a control interface 25 connected to the control module 20, an ASIC (Application Specific Integrated Circuit) 26 and a network 28 of eight planar antennas (which may be called "patches"). The ASIC 26 is the source of millimeter wave radiation. It is the ASIC 26 that generates the radiation so that it is transmitted to the antenna network 28. With reference to application FR1758634, one of the technical characteristics of this arrangement is that a single ASIC 26 is associated with eight different antennas 28 and separate circuits, as shown on the front and back of the same module 22, respectively. Figure 4 and Figure 5 As shown. Since there is a single ASIC rather than multiple ASICs to power the eight antennas, the resulting power loss is compensated by improved antenna performance. The interface 25 may be located in the control module 20.

[0100] like Figure 7 The ASIC 26 shown includes an oscillator 32, a power amplifier 34, and digital components 36 for setting and controlling the ASIC. Figure 8 As shown in more detail in FIG, the ASIC also includes a frequency divider 31, a communication bus 35, a pulse width modulation (PWM) control 37, a reference frequency generator 33, and a comparator 38. An oscillator 32 generates the operating frequency of the ASIC. An amplifier amplifies this signal so that the desired power is achieved at the component output. This power is adjustable between 0 and 60 mW. A power management circuit ensures that all component functions are properly powered. The PWM control unit enables the HF output signal to be transmitted continuously or discontinuously.

[0101] Frequency comparator 38 and frequency divider 31 enable detection of the frequency of the radiation emitted by ASIC 26. In reality, oscillator 32 is an internal component of ASIC 26, making it impossible to determine the frequency of the radiation generated by oscillator 32. However, this frequency may be involuntarily altered by other components or by temperature fluctuations. To measure this frequency, the following procedure is employed: reference frequency generator 33, acting as an external oscillator, generates a 10 MHz signal. On the other hand, based on the output radiation of ASIC 26, frequency divider 31 generates a derived signal by dividing the frequency value of the output signal by 3840. This signal is an approximate sub-multiple of the signal emitted to the skin. The reference signal from generator 33 and the derived signal from frequency divider 31 are then compared by comparator 38. Since the reference signal's frequency is known (10 MHz) and the derived frequency is the result of dividing the frequency of the output signal by 3840, comparator 38 enables the actual frequency of the output signal to be determined with an accuracy of approximately 8 MHz. If the found frequency differs too much from its expected value, the external controller can request the oscillator 32 to reduce or slightly increase its frequency. This check thus ensures that the output frequency will be within the selected frequency band, most often 61 to 61.5 GHz. It also makes it possible to verify that the frequency of the output signal of each ASIC is different, in order to avoid interference fringes. In practice, in a device 10 comprising two modules 22 and 24, and thus four ASICs 26, the output frequencies of these ASICs are set so that they differ by at least 100 MHz. Thus, the four frequencies can be 61.1, 61.2, 61.3, and 61.4 GHz, respectively.

[0102] The manufacturing principle of the ASIC is similar to that described in application FR1758634. Therefore, the ASIC 26 is manufactured using CMOS (Complementary Metal Oxide Semiconductor) technology, which is well known to those skilled in the art and therefore will not be described in detail here. More specifically, the transistors are of the 65 nanometer CMOS type. Alternatively, they could be developed using silicon germanium (SiGe) or even gallium arsenide (GaAs). On the other hand, Gunn diode-type technology does not allow for the minimum size and desired cost. The ASIC 26 thus comprises a silicon integrated circuit housed in a BGA (Ball Grid Array) type package, a type well known to those skilled in the art, specifically designed for the ASIC 26 and including solder balls (also known as "bumps"). The frequency oscillator 32 is housed in a cavity (not shown) within the package, intended not to interfere with the generated frequency. In this case, the dimensions of the BGA block containing the ASIC are 2.2 by 2.2 by 0.9 millimeters.

[0103] like Figure 4 and 5 As shown, each millimeter wave transmission module 22 and 24 includes two of these ASICs 26, each ASIC 26 being independently associated with a network 28 of eight radiating patches in its respective circuit. These ASICs 26 and the associated antenna network 28 are arranged on both sides of a substrate 39. The connection between the ASICs 26 and the antennas 28 is achieved by "solder balls" passing through the substrate 39. This component grouping allows for minimizing electromagnetic wave losses. The antenna 28, which receives the radiation generated by the ASICs 26 associated therewith, transmits electromagnetic waves intended for the skin of the patient 1. Below, the substrate 39 and the antennas (or radiating patches) 28 will be described in more detail.

[0104] In summary, each of the two wave transmission modules 22 and 24 includes two ASICs 26 and sixteen antennas 28, located on a substrate 39 via two separate circuits. The total dimensions of each of these modules are 16.5 mm by 17 mm by 2 mm, meaning each module has a total circuit area of ​​2.8 square centimeters and a volume of 0.56 cubic centimeters, or less than 3 square centimeters in area and less than 0.6 cubic centimeters in volume. Considering the antenna network's radome 52 (described below) as part of the module, the module measures 16.5 mm by 17 mm by 2.8 mm, resulting in a volume of less than 0.8 cubic centimeters. Finally, considering the assembly formed by the transmission module 22 or 24, radome 52, and thermal gap pad (conventional to those skilled in the art) integrated into the wristband 10, the assembly measures 22 by 20 by 6 mm, less than 2.7 cubic centimeters. These modules are smaller than those of the prior art, making them easier to integrate into the device 10 and, as explained below, allowing for improved radiation efficiency of the antennas 28. Another important advantage of dividing the module into two smaller modules will be explained below.

[0105] B – Multi-part integration

[0106] like Figure 3 As shown, modules 22 and 24 are arranged at separate locations on the wristband 10. This allows the emission of millimeter waves towards two separate parts of the patient's wrist, as shown in FIG. Figure 9 Schematically shown at point 6 in FIG. Because these rigid modules 22 and 24 are smaller than those in application FR1758634, they conform more closely to the nearly round shape of the human wrist. This prevents the formation of air gaps between the wrist and modules 22 and 24, making the radiation emitted by each module's sixteen antennas 28 more efficient. In other words, the overall efficiency of the two modules 22 and 24 is improved compared to the single module in application FR1758634.

[0107] exist Figure 10 and 11 The mechanical integration of the wave transmission modules 22 and 24 is shown in FIG. The control module 20 integrated in the top of the wristband 10 is connected to the transmission modules 22 and 24 via a flexible "flex" 40. "Flex" refers to a flexible printed circuit, also known as a "flexible printed circuit", which is well known to those skilled in the art and enables the creation of electrical connections that can withstand winding or other types of bending. Figure 10 In the embodiment, the flexible band 40 comprises a single component which is then divided into two flexible band parts, each of which is connected to one of the two wave emission modules 22 and 24. Thus, the two emission modules 22 and 24 can be integrated in the bracelet 10 independently of each other, in particular at two different locations 6.

[0108] The connection between the flexible band and the three elements—the control module 20, the wave emission modules 22 and 24—is achieved through an electrical connector 29 acting as an intermediate piece between the flexible circuit 40 and the rigid circuits of the three modules 20, 22 and 24. Furthermore, the control module 20 is connected to a battery 21. This battery thus makes it possible to power all the components of the bracelet 10 through the modules 20.

[0109] The integration of two small wave emission modules 22 and 24 flexibly connected to the control module 20 into the device 10 is much easier than the integration of the wave emission module from application FR 1 758 634, whose total size is the size of the assembly formed by these two modules 22 and 24 when placed next to each other. In other words, for the same "module volume", the mechanical integration of a module manufactured in multiple parts is much easier.

[0110] It should be noted that, as mentioned above, the division of the module into two smaller modules 22 and 24 also makes it possible to avoid the presence of air gaps, since the smaller surface of the module can better conform to the nearly round shape of the wrist than a larger rigid surface. Thus, whatever the radiating element 2 of the module, the division of the module into two parts will improve its efficiency and facilitate its mechanical integration.

[0111] However, the radiating elements 28 of the module described and illustrated are also improved so that their performance itself is also made better compared to the radiating elements of prior art devices.These improved radiating elements 28 will now be explained.

[0112] II. Antenna Network

[0113] The antenna network of the present invention is improved in several aspects to increase its efficiency and testability (ease of testing the antenna) and reduce its manufacturing costs compared to the antenna network disclosed in application FR 1 758 634. Thus, for the same amount of energy delivered to the skin, less energy is emitted at the radiation source.

[0114] A-Substrate

[0115] Each ASIC 26 is soldered to two layers of an "HF" substrate made of MT77 (from the manufacturer ISOLA), which makes it possible to limit the losses of high-frequency electromagnetic radiation as much as possible. MT77 was chosen for its characteristics: at a frequency of 61.25 GHz, it has a dielectric constant of 3 and a dissipation factor of 0.0017. More generally, the dielectric constant of the material of these substrate layers advantageously has values ​​of 2.9 to 3.1 and a dissipation factor of 0.0010 to 0.0020. The two substrate layers are 0.254 mm thick and make it possible to improve the radiation efficiency of the antenna by approximately 20% compared to prior art devices made of thicker layers. It is therefore advantageous for such layers to have a thickness of 0.1 to 0.6 mm, preferably 0.2 to 0.3 mm. They are separated by two layers of prepreg Astra-MT77 and a copper layer. In addition, the connections between the different layers of the substrate are made by vias. Once assembled, all the layers forming the substrate are 0.8 mm thick. Of course, the type of layers and their number can be different.

[0116] B-Patch

[0117] Hereinafter, as in the remainder of the detailed description, the term "antenna" or "patch" will be used to refer to the radiating element 28 of the antenna network (or array).

[0118] exist Figure 13 The radiating elements 28 shown schematically in FIG are flat patches with an area of ​​1*1.6 mm. The size of their central openings is 0.9*0.18 mm. Figure 14 As shown in FIG, they are spaced 2.4 mm apart along the longitudinal axis of the module, i.e., half a wavelength at a frequency of 61.25 GHz, and have a width of 2.6 mm. In practice, this spacing, which is close to half a wavelength in a vacuum, improves the uniformity of the radiation and its efficiency. Of course, small variations in distance have no significant effect, but it is considered more preferred that the antennas 28 are spaced apart by a distance ranging from 2.3 to 2.5 mm.

[0119] On a printed circuit comprising the ASIC 26 and eight antennas 28, these antennas are thus able to cover an area between 0.625 and 1 cm 2 Since each module 22 (or 24) includes two circuits and thus sixteen antennas, the electromagnetic wave transmitting module is capable of transmitting electromagnetic waves in a range from 1.25 to 2 cm. 2Since device 10 includes two modules (22 and 24), it can expose at least 2.5 square centimeters of skin to the waves, which, according to scientific literature, is sufficient to produce therapeutic effects, particularly for treating chronic pain. Furthermore, one of the two modules 22 or 24 can be deactivated to determine whether the therapeutic effect can be sustained on the patient while saving energy. In this case, only 1.25 square centimeters of skin are exposed to the waves. A minimum exposure of 1 square centimeter is considered sufficient for perceiving therapeutic effects.

[0120] Moreover, if Figure 14 As shown, there are through-holes 43 along the edge of the circuit, thereby forming the walls of the through-holes 43. Their diameter is 200 microns each, and their pitch (the distance separating the centers of each through-hole) is 400 microns. The walls 43 of these through-holes form a cavity whose resonant frequency may be in the frequency band used by the module. To avoid this, it may be necessary to change the position of some of the through-holes, which is within the ability of a person skilled in the art. It is particularly useful that the resonant frequency of the cavity is different from the frequency band from 55 to 65 GHz, which is particularly useful in the context of the present invention.

[0121] C-radome

[0122] Reference Figure 12 Each patch 28 radiates waves through a radome 52 to the patient's skin 60. "Radome" refers to any element of an antenna, array, network of antennas, or radiating patch that has a surface intended to cover the patient's skin. It can also be called a "cover" or "hood." In the field of antennas, a radome is thus a cover for a radiating element. Figure 12The diagram is schematic and not drawn to scale. When the device is normally worn by the user, there is no space between radome 52 and skin 60. Furthermore, one of the objectives of the present invention is to avoid creating an air gap between the antenna and the skin. Therefore, in the context of the present invention, it is advantageous for radome 52 to be made of a biocompatible material, as it will be in contact with the patient's skin. Here, radome 52 is made of polycarbonate and is designed to adapt the antenna's impedance to the impedance of skin 60. This is because, by default, when the radome is absent, the antenna is designed to radiate in air. When testing the antenna, these tests are performed in air, making it suitable to perform these tests without radome 52. However, within the framework of the present invention, the antenna is intended to radiate toward human skin. In prior art devices, the radome is present solely to protect the antenna, but here it acts as an impedance adapter. The goal is to adapt the impedance of an antenna designed to radiate in air (which is approximately 377 ohms, the impedance in empty space) to the impedance of the skin, which has a complex dielectric constant of approximately 8–11 J. The dielectric constant of the radome material and the selected thickness allow the antenna to be adapted to the impedance of the skin to maximize the energy transferred from the antenna to the skin. This is explained below.

[0123] To achieve this impedance matching, a polycarbonate radome can be fabricated, as described herein, but other biocompatible materials with suitable impedance, such as polyoxymethylene copolymers, can also be used. The choice of material depends, in particular, on the dissipation factor and dielectric constant of the material at the frequencies most commonly used in the module. Thus, to optimally match the antenna impedance to the impedance of dry skin, multiple tests have shown that, given a polycarbonate radome with a dielectric constant of 2.8 and a dissipation factor of 0.01 at 61.25 GHz, its thickness should be 0.6 mm or 2.0 mm. For polyoxymethylene copolymers, with a dielectric constant of 3.8 and a dissipation factor of 0.006 to 0.18, the radome thickness should be 0.5 mm or 1.7 mm. Other values ​​are, of course, possible: more generally, it is advantageous for the radome to have a dielectric constant of less than or equal to 4 and a dissipation factor of less than or equal to 0.2 to achieve near-optimal impedance matching. The smaller the thickness, the lower the transmission loss. Here, a polycarbonate thickness of 0.6 mm was chosen, which is also suitable for injection molding. Alternatively, while retaining the same impedance matching, the radome could be given a thickness of approximately 1.4 times greater, corresponding to half a wavelength in polycarbonate at a frequency of 61.25 GHz. In this case, the impedance matching remains essentially the same.

[0124] The present invention is not limited to the embodiments described, and other embodiments will be apparent to those skilled in the art.

[0125] In particular, the wave transmission module can be used in devices other than wristbands or watches, or in wristband-like devices that are suitable for areas other than the wrist (e.g., around the ankle or any other location). Furthermore, other types of antennas than those described herein can be integrated into the device.

[0126] Accordingly, the antenna elements described herein may be integrated into any other type of module or device, not only the wave transmitting modules described.

[0127] However, the association of modules with this antenna network makes it possible to significantly improve the performance of the wave emission device in which they are integrated.

[0128] Finally, the module may be intended for applications other than treating pain. Indeed, emitting millimeter waves may be intended specifically to relieve stress or tension, or more generally to produce a good feeling.

Claims

1. A patch antenna (28) for near-field radiation, comprising an element (52) having a surface intended to cover the skin of a user (1), the element (52) being arranged so that the impedance of the patch antenna (28) matches the impedance of the skin, wherein When electromagnetic waves pass through the element (52) at a frequency of 61.25 GHz, the element (52) has an intrinsic impedance value between the intrinsic impedance value of air and the intrinsic impedance value of dry skin derived from its 8-j11 complex dielectric constant.

2. The patch antenna (28) of claim 1, wherein: The element (52) comprises a biocompatible material.

3. The patch antenna (28) of claim 1, wherein: The element (52) consists only of polycarbonate and has a thickness ranging from 0.5 mm to 3 mm.

4. The patch antenna (28) of claim 3, wherein: The thickness of the element (52) is 0.6 mm, or an integer multiple of 0.6 mm plus half the wavelength of the electromagnetic wave when the electromagnetic wave passes through the element (52).

5. The patch antenna (28) according to any one of claims 1 to 4, wherein The dielectric constant of the element (52) has a value less than or equal to 4, and a dissipation factor less than or equal to 0.

2.

6. The patch antenna (28) according to any one of claims 1 to 4, comprising a diameter equal to or less than 10 cm 2 The main area value of .

7. The patch antenna (28) according to any one of claims 1 to 4, comprising at least eight patch devices for radiating electromagnetic waves, the patch devices being located on a same substrate (39) and spaced apart from each other by a spacing value between 2.4 and 2.5 mm, the eight patch devices being capable of radiating electromagnetic waves by a distance between 0.625 cm and 0.625 cm. 2 Up to 1cm 2 The continuous area between them is exposed to electromagnetic radiation.

8. The patch antenna (28) of any one of claims 1 to 4, comprising a printed circuit board having a substrate, wherein when an electromagnetic wave passes through the element (52) at a frequency of 61.25 GHz, the dielectric constant of the substrate has a value of 2.9 to 3.1, the dissipation factor has a value of 0.0010 to 0.0020, the thickness of the substrate layer has a value of 0.1 to 0.6 mm, and the total substrate assembly thickness is between 0.5 and 1.6 mm.

9. The patch antenna (28) of claim 8, wherein: The thickness of the layer of the substrate has a value of 0.2 to 0.3 mm.

10. The patch antenna (28) of claim 8, wherein the patch antenna (28) comprises a through-hole fence at all edges of the substrate, wherein the diameter of the through holes (43) of the fence is greater than or equal to 175 microns, and the spacing between the through holes is greater than or equal to 300 microns.

11. The patch antenna (28) of claim 10, wherein: A cavity is formed by the via fence, the cavity being configured such that a resonance frequency of the cavity has a value outside a frequency range from 55 GHz to 65 GHz.

12. An electromagnetic wave transmitting module (22, 24), wherein: The electromagnetic wave transmission module has a total volume of less than 1 cubic centimeter and includes at least one electromagnetic wave radiation source (26) connected to at least one transmitting antenna, wherein the transmitting antenna is capable of transmitting electromagnetic waves with a power density of at least 0.5 milliwatts per square centimeter when the electromagnetic wave transmission module is arranged at a surface, and the electromagnetic wave transmission module further includes: - a frequency generator (33) capable of generating a reference frequency; - a frequency measuring device (38) capable of measuring a frequency derived from the frequency of the radiation emitted by said electromagnetic wave radiation source; and - a frequency comparator (31) capable of comparing said derived frequency with said reference frequency.

13. The electromagnetic wave transmitting module (22, 24) according to claim 12, wherein: The surface is skin and the transmitting antenna comprises an element (52) having a surface intended to cover the skin.

14. The electromagnetic wave transmitting module (22, 24) according to claim 12 or 13, wherein: The power density of the electromagnetic wave is between 5 and 35 milliwatts per square centimeter.

15. The electromagnetic wave transmitting module (22, 24) according to any one of claims 12 to 13, wherein: The frequency of the electromagnetic wave is in the range of 3 GHz to 120 GHz.

16. The electromagnetic wave transmitting module (22, 24) according to claim 15, wherein: The frequency of the electromagnetic wave is 55 GHz to 65 GHz.

17. The electromagnetic wave transmitting module (22, 24) according to any one of claims 12 to 13, wherein: The electromagnetic wave radiation source (26) is a dedicated integrated circuit having a total volume value of less than 5 cubic millimeters and capable of generating radiation emitted by the transmitting antenna when it is powered on.

18. The electromagnetic wave transmitting module (22, 24) according to any one of claims 12 to 13, wherein: The transmitting antenna comprises a planar antenna or a network of planar antennas, and the main area value of the planar antenna or the network of planar antennas is 0.5 cm 2 Up to 2cm 2 , the planar antenna or the network of planar antennas is capable of emitting said radiation towards the surface when it is energized by the radiation generated by the source of electromagnetic wave radiation (26).

19. The electromagnetic wave transmitting module (22, 24) according to any one of claims 12 to 13, wherein: The electromagnetic wave radiation source (26) is connected to at least four different transmitting antennas.

20. The electromagnetic wave transmitting module (22, 24) according to claim 19, wherein: At least some of the transmitting antennas form a network of antennas connected to each other.

21. The electromagnetic wave transmitting module (22, 24) according to claim 19, wherein: The electromagnetic wave radiation source (26) is connected to eight different transmitting antennas.

22. The electromagnetic wave transmitting module (22, 24) according to claim 21, wherein: At least some of the transmitting antennas form a network of antennas connected to each other.

23. The electromagnetic wave transmitting module (22, 24) according to claim 21, wherein: The electromagnetic wave transmission module includes two separate electromagnetic wave radiation sources (26), wherein each electromagnetic wave radiation source (26) is connected to eight separate transmission antennas.

24. The electromagnetic wave transmitting module (22, 24) according to claim 23, wherein: At least some of the transmitting antennas form a network of antennas connected to each other.

25. A portable device (10) for transmitting electromagnetic waves, comprising at least two electromagnetic wave transmitting modules (22, 24) according to any one of claims 12 to 24 and a power supply (21) for supplying power to the electromagnetic wave transmitting modules.

26. The portable device (10) of claim 25, wherein: The electromagnetic wave emitting modules (22, 24) are configured to expose non-adjacent respective areas of the surface to electromagnetic waves.

27. The portable device (10) according to claim 25 or 26, wherein The portable device is capable of simultaneously exposing a total of at least 1 square centimeter of the surface to the electromagnetic waves.

28. The portable device (10) of claim 27, wherein: The portable device is capable of simultaneously exposing a total of at least 2.5 square centimeters of the surface to the electromagnetic waves.

29. The portable device (10) according to any one of claims 25 to 26, wherein Each of the electromagnetic wave emission modules (22, 24) is electrically connected to the power supply (21) via respective flexible electrical connection devices (29, 40).

30. The portable device (10) according to any one of claims 25 to 26, wherein The portable device comprises a control module (20) for controlling the electromagnetic wave emission module, the control module being different from the power supply (21) and also different from each electromagnetic wave emission module (22, 24), and the control module (20) being electrically connected to the power supply (21) and each electromagnetic wave emission module via respective flexible electrical connection devices.

31. The portable device (10) of claim 30, wherein: At least some of the flexible electrical connections are flexible printed circuits.

32. The portable device (10) according to any one of claims 25 to 26, wherein: The portable device comprises a flexible wristband (10), in which the electromagnetic wave transmitting modules (22, 24) are arranged to expose different parts (6) of the surface of the wrist to electromagnetic waves.

33. The portable device (10) according to any one of claims 25 to 26, wherein The portable device is wearable at at least one of the following locations: - On the face; - around the wrist; - on one leg; - around the ankle; - on the back; - one ear; or -In the palm of one hand.

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