Patent Grant
12119546
The present application is a National Phase of International Application Number PCT/EP2022/061499 filed Apr. 29, 2022, which designated the U.S. and claims priority benefits from French Application Number FR 2106798 filed Jun. 24, 2021, the entire contents of each of which are hereby incorporated by reference.
The field of the invention is that of satellite platforms.
More particularly, the invention relates to a satellite platform having improved electromagnetic decoupling characteristics between radiating elements of the platform.
Thus, the invention has applications, in particular, yet not exclusively, for all satellite platforms for which the electromagnetic couplings between radiating elements are a major problem, like, for example, satellite platforms with small dimensions.
In the spatial industry, a growing interest for communication and observation satellites, and in particular for constellations of satellites comprising a multitude of small-sized satellites, is observed. As a non-limiting example, mention may be made of the Starlink, Kineis, OneWeb or C03D constellations. This growing interest is accompanied by a multiplication of the radiocommunications links and the operating frequencies implemented by the payload of the platform. This results in an increasing need for antennas to be accommodated in particular on platforms with decreased dimensions. The document EP2863473 filed on the name Airbus Defence and Space GMBH and entitled “Space-borne antenna system”, discloses a decoupling RF seal between two panels each having a radiation surface.
The present invention aims to further improve decoupling between electromagnetic radiation receiver and transmitter elements present on a satellite platform.
The invention relates to a satellite platform comprising a plurality of radiating elements of the electromagnetic radiation receiver and/or transmitter type, including at least one transmitter radiating element. Such a satellite platform comprises at least one block of electromagnetic absorbing material comprising a cellular material impregnated with an electromagnetic absorbing filled resin in a frequency band of interest to decrease electromagnetic coupling between the radiating elements. The block of material is implemented in at least one region of interest on the satellite platform to decrease electromagnetic coupling, the region of interest intersecting at least one predominant coupling path between at least two of said radiating elements.
In some embodiments, the block of electromagnetic absorbing material consists exclusively of the cellular material impregnated with the electromagnetic absorbing filled resin.
In some embodiments, the block of electromagnetic absorbing material is an affixed element such as an electromagnetic absorbent fastened to an outer surface of the satellite.
In some embodiments, the predominant path is of the direct type and corresponds to a direct view between the two radiating elements.
In some embodiments, the predominant path is of the indirect type corresponding to an indirect interaction between the two radiating elements.
In some embodiments, the predominant path corresponds to the path where the intensity of the electromagnetic field is higher than a determined threshold beyond which the risk of electromagnetic disturbance between the two radiating elements is significant.
In some embodiments, the frequency band of interest is an operating frequency band of a receiver system processing the wave captured by one of the two radiating elements. The electromagnetic absorbing material has an attenuation determined in the frequency band of interest so as to guarantee a predetermined level of performances of the receiver system.
In some embodiments, the region of interest extends over an external face of the satellite platform. The block of absorbing material, occupying the region of interest, has characteristic dimensions smaller than the largest dimension of the platform so as to achieve a local electromagnetic absorption.
In some embodiments, the cellular material has a mesh size comprised between 3 and 12 millimeters so as to be able to receive at least one surface layer of resin filled by impregnation according to an amount comprised between 5 kilograms and 150 kilograms per cubic meter, so that the block of absorbing material keeps a hollow structure.
In some embodiments, the filled resin comprises a phenolic resin, or an acrylic paint, filled with carbon black particles.
In some embodiments, the cell walls of the cellular material are arranged perpendicularly to an external face of the satellite platform.
The invention also relates to a process for constructing a satellite platform comprising a plurality of radiating elements of the electromagnetic radiation receiver or transmitter type, including at least one transmitter radiating element, characterized in that it comprises:
In some embodiments, the step of determining the predominant path comprises calculating an electromagnetic coupling in the absence of absorbing material and comparing the electromagnetic coupling with a predetermined threshold to decide to implement a predetermined absorption treatment.
In some embodiments, the block of electromagnetic absorbing material consists exclusively of the cellular material impregnated with the electromagnetic absorbing filled resin.
In some embodiments, the electromagnetic absorbing resin is obtained by injecting carbon black particles into a phenolic resin or an acrylic paint.
In some embodiments, the step of obtaining the block of electromagnetic absorbing material comprises a step of determining a target permittivity for the block of electromagnetic absorbing material according to the predetermined absorption treatment.
In some embodiments, the step of obtaining the block of electromagnetic absorbing material comprises a step of determining, according to the target permittivity, at least one parameter from the group comprising:
In some embodiments, the cellular material is selected with a mesh size comprised between 3 and 12 millimeters to receive a surface layer of an electromagnetic absorbing resin by impregnation according to an amount comprised between 5 kilograms and 150 kilograms per cubic meter, so that the block of absorbing material keeps a hollow structure.
In some embodiments, the step of obtaining said block of electromagnetic absorbing material comprises a step of measuring the permittivity of said absorbing material electromagnetic followed, if the target permittivity is not reached, with a new impregnation step.
In some embodiments, the step of determining the region of interest comprises determining the size of said block of absorbing material and of said region of interest extending over an external face of the satellite platform. The block of absorbing material, occupying the region of interest, has characteristic dimensions smaller than the largest dimension of the platform so as to achieve a local electromagnetic absorption.
The invention also relates to a process for constructing a satellite platform comprising a plurality of radiating elements of the electromagnetic radiation receiver or transmitter type, including at least one transmitter radiating element, characterized in that it comprises:
For example, such a satellite platform obtained by implementation of the construction process according to the invention is a satellite platform as described before (according to any one of the aforementioned embodiments).
Advantageously, the invention improves the decoupling between intentional or unintentional electromagnetic radiation receiver and transmitter elements, such as the antennas of communication systems or the elements of Hall effect motors, through the use of a material having electromagnetic absorption characteristics in a corresponding frequency band. More particularly, such a material is herein implemented in a region of interest in order to obtain the desired decrease.
Another advantage of the invention is that it is possible to cut off a path between two radiating elements where, in particular, creeping waves propagate along one face of the satellite, in direct view to cut off a direct coupling path or in indirect view to cut off an indirect coupling path by reflection, diffraction, dual diffraction or scattering.
Still advantageously, the cellular material, for example based on an aramid such as honeycomb Nomex®, may have a mesh size particularly suited to aeronautical and space applications. Moreover, such a material can be easily filled with an electromagnetic absorbing resin.
Other aims, features and advantages of the invention will appear more clearly upon reading the following description, given as a simple illustrative and non-limiting example, with reference to the figures, wherein:
1 shows a partial detailed view of the docking structure of the platform of
2 shows a detailed view of the docking structure of the platform of
1 shows a partial detailed view of the docking structure of the platform of
2 shows a detailed view of the docking structure of the platform of
The radiofrequency electromagnetic couplings increase because of the proximity between the different antenna accesses on platforms with decreased dimensions, this tendency being aggravated in particular at low frequencies.
Moreover, a generalization of the electric propulsion through the use of Hall effect motors is also noticed for such satellite platforms. These motors are a first order broadband electromagnetic noise source for onboard receivers, particularly at low frequencies (typically for frequencies ranging from the VHF band to the S band).
The use of such electric motors associated with increasingly close radio frequency transmitters and receivers leads to new electromagnetic compatibility problems at such satellite platforms. Moreover, such problems are aggravated on satellite platforms with decreased dimensions as mentioned hereinabove.
The general principle of the invention is based in particular on the implementation of an electromagnetic absorbing material comprising a cellular material impregnated with a filled resin electromagnetically absorbing in a frequency band of interest to decrease electromagnetic coupling between radiating elements of the electromagnetic radiation receiver and/or transmitter type on a satellite platform. More particularly, the material is implemented in at least one region of interest of the satellite platform to decrease electromagnetic coupling. Such a region of interest intersects one or more predominant coupling path(s) between several radiating elements. Thus, the electromagnetic coupling is decreased to an acceptable threshold.
The expression “frequency band of interest” herein refers to the frequency band in which a decrease in the electromagnetic coupling between the considered radiating elements has an interest with regards to the improvement of the operating performances of the radiofrequency transmitters and/or receivers associated with all or part of the considered radiating elements. Moreover, by “electromagnetic absorbing material”, it should be understood any material attenuating the electromagnetic waves propagating along the considered coupling path in a given frequency band, in this case the frequency band of interest. For example, such an attenuation is obtained within the mere absorbing material by dissipation of the electromagnetic energy into thermal energy.
Referring to
More particularly, the satellite platform 100 comprises a docking structure 110 intended to accommodate the main functional subassemblies of the satellite (for example the flight or propulsion control system), as well as deployable solar panels 120.
In some embodiments, other satellite platform structures are considered, for example with other energy sources than solar panels.
Returning back to
More particularly, the electromagnetic coupling between the output 112 and the antenna 111 would predominantly take place via the coupling path 120. In practice, such a predominant coupling path 120 corresponds to a path where the intensity of the electromagnetic field is higher than a determined threshold. For example, such a threshold is defined as a threshold beyond which the risk of electromagnetic disturbance of the antenna 111 via the output 112 is significant, i.e. has a significant impact on the reception performances of the receiver system processing the signals received via the antenna 111.
According to such an example, the frequency band of interest corresponds to the operating frequency band of the GPS receiver, i.e. a band comprising the frequencies 1,575.42 MHz and 1,227.60 MHz. The electromagnetic absorbing material has a determined attenuation in the considered frequency band so as to guarantee a predetermined level of performances of the GPS system, for example with regards to the quality of reception parameters such as the SNR (standing for “Signal to Noise Ratio”) or the BER (standing for “Bit Error Rate”). The same approach may be followed for any receiver system processing a wave captured by a radiating element subjected to an electromagnetic disturbance induced by a transmitter radiating element of the satellite platform. For example, the block of electromagnetic absorbing material induces an attenuation of at least 5 dB, for example in the L and S bands.
In the case illustrated in
In general, a satellite platform according to the invention comprises a plurality of radiating elements of the electromagnetic radiation receiver and/or transmitter type, including at least one transmitter. More particularly, such electromagnetic radiation is intentional or unintentional. For example, the considered radiating elements consist of antennas of communication systems as well as Hall-effect motors as described hereinabove.
Returning back to
Indeed, the coupling paths correspond to parasitic radiation phenomena inducing waves propagating in particular along the conductive external surfaces of the satellite platform 100.
Thus, a coupling path, for example of the creeping path type, could appear between two radiating elements, even implanted on different faces of the satellite platform 100. In general, the external partition of the satellite platform 100 tends to guide this parasitic wave.
Thus, it is possible, for example, to cut off a path where creeping waves propagate along one face of the satellite, in direct view (i.e. a direct coupling path) or in indirect view (i.e. an indirect coupling path by reflection, dual diffraction or scattering).
In some embodiments, the block of absorbing material takes on other shapes, for example a ring or lozenge like shape.
For example,
In some embodiments wherein the satellite platform 100 comprises different radiating elements of the electromagnetic radiation receiver and/or transmitter type, several coupling paths between different radiating elements may exist. Thus, different blocks with the same geometry or with different geometries, and with the same dimensions or with different dimensions, of absorbing materials may be implemented in different regions of interest of the satellite platform. These blocks of materials may have identical or distinct radiofrequency absorption characteristics, for example with absorptions optimized for different frequency bands.
Returning back to
According to the embodiment of
More particularly, the cellular material 210 has a mesh size 220 of a few millimeters, for example from 3 to 12 millimeters, in order to be able to receive one or more surface layer(s) of resin filled by impregnation. For example, the amount of impregnated resin is comprised between a few kilograms, for example 5 kilograms, and 150 kilograms per cubic meter. Thus, the block of absorbing material keeps a hollow structure. Moreover, such a resin filler allows obtaining good electromagnetic absorption performances without the material 200 becoming conductive.
For example, the cellular material 210 has a mesh size 220 of 4.6 mm, 6.4 mm or 9.6 mm particularly suited to aeronautical and space applications. For example, the height of the cells is 5 cm. For example, such a cellular material 210 is based on aramid such as for example Nomex®.
In some embodiments, the block of electromagnetic absorbing material consists exclusively of the cellular material 210 impregnated with the electromagnetic absorbing filled resin. In some embodiments, the filled resin comprises a phenolic resin, or an acrylic paint, filled with carbon black particles. For example, the charge rate is preferably between 5 and 20% by weight, even more preferably between 6 and 12% by weight, in order to obtain good electromagnetic absorption performances.
In some embodiments, the cell walls 230 of the cellular material 210 are arranged perpendicularly to an external face of the satellite platform 100. Advantageously, this leads to better decoupling performances. By passing from cells oriented along an external face to cells oriented normally to the external face, such an improvement is for example in the range of 5 dB in the L and S band, and more than 10 dB in the X band and beyond.
For example, the satellite platform 100 is obtained by implementation of the construction process now described with reference to
Considering more particularly the embodiment of the satellite platform 100 of
For example, a calculation of the electromagnetic coupling between the output 112 and the antenna 111 is implemented in the absence of absorbing material. For example, such a calculation is carried out by numerical simulation based on a 3D model of the satellite platform 100, or at least of the docking structure 110. Thus, each electromagnetic coupling is determined by calculation and compared with a predetermined threshold in order to decide whether this path 120 is a predominant path or not as described hereinabove with reference to
In particular, the comparison allows deciding to implement an absorption treatment, in order to decrease the coupling between the output 112 and the antenna 111. In other words, when the electromagnetic coupling between the output 112 and the antenna 111 is greater than the predetermined threshold, it is decided to implement the considered treatment.
In other embodiments, the predominant coupling path 120 between the output 112 and the antenna 111 is determined in another manner, for example empirically, or based on measurements obtained on previous implementations, like for example in the case of satellite platforms produced in series.
Returning back to
For example, step E310 comprises determining the size of a block 155 of absorbing material to be implemented in the region of interest. Such a block 155 of absorbing material, parallelepiped shaped, has characteristic dimensions smaller than the largest dimension of the docking structure 110 so as to achieve a local electromagnetic absorption.
In some embodiments, the block of absorbing material takes on other shapes, for example a ring like shape. It is possible to consider blocks of electromagnetic absorbing material having an oval or lozenge profile. An example of an oval surface 160 where creeping waves propagate is for example shown in
Returning back to
Thus, during a step E320a, a target permittivity for the block 155, 165 of electromagnetic absorbing material is determined according to the desired predetermined absorption treatment. In other words, the target permittivity is determined, for example by electromagnetic simulation, so as to obtain desired absorption properties for the absorbing material.
In some embodiments, step E320a is not implemented and the target permittivity is already known, for example empirically or based on previous implementations.
As described hereinabove with reference to
Thus, during a sizing step E320b, in
For example, the cellular material is selected with a mesh size of a few millimeters, for example from 3 to 12 millimeters, to receive a surface layer of an electromagnetic absorbing resin by impregnation in an amount comprised between a few kilograms, for example 5 kilograms, and 150 kilograms per cubic meter, so that the block of absorbing material keeps a hollow structure.
During a step E320c of manufacturing the resin, the electromagnetic absorbing resin is obtained by injecting carbon black particles into a phenolic resin or into an acrylic paint, depending on the parameter(s) obtained upon implementation of the sizing step E320b.
During a next step E320d, the cellular material 210 is impregnated with the electromagnetic absorbing filled resin obtained during the previous step E320c. For example, such an impregnation is done by soaking or gun spraying.
In some embodiments, the step E320c of manufacturing the resin is not implemented, the filled resin, being for example obtained from a supplier.
Returning back to
The measurement thus obtained is compared with the target permittivity. For example, if the target permittivity is not reached, a new impregnation step E320d is for example implemented. Thus, the measurement performed during step E320e is an intermediate measurement or, where appropriate, a final measurement.
After manufacture of the block 155, 165 of absorbing material, during a step E330, the block 155, 165 of absorbing material is implemented in the region of interest over a determined area 150, 160 of one face of the platform. For example, the block of material is fastened on the external partition of the satellite platform 100 by gluing, using brackets or using a mechanical holding structure.
The block of electromagnetic absorbing material is an affixed element such as a radiofrequency absorbent fastened to an outer surface of the satellite. Thus, the block of electromagnetic absorbing material has no support function. The block of electromagnetic absorbing material is not a structural element like a partition delimiting the interior of the satellite or a support structural element.
In some embodiments, the cell walls 230 of the cellular material 210 are arranged perpendicularly to an external face of the satellite platform 100. This advantageously leads to better decoupling performances.
In some embodiments, the steps E320a of determining the target permittivity, E320b of dimensioning the block and/or E320e of measuring are not necessarily implemented, in particular when the composition of the absorbing material to be obtained is already known. Thus, all it remains then is to manufacture it by implementing the resin manufacturing E320c and impregnation E320d steps.
Thus, in general, the implementation of the process of
In particular, in the aforementioned embodiments wherein the satellite platform comprises different radiating elements of the electromagnetic radiation receiver and/or transmitter type and wherein there is a plurality of coupling paths between different radiating elements, the different steps of the above-described construction process (according to any one of the aforementioned embodiments) may be implemented several times for different couplings existing between two radiating elements of the satellite platform. In this manner, several blocks of absorbing materials could be implemented in different regions of interest of the platform.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2106798 | Jun 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/061499 | 4/29/2022 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2022/268384 | 12/29/2022 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6097327 | Byquist et al. | Aug 2000 | A |
| 6217978 | Murase et al. | Apr 2001 | B1 |
| 9640873 | Pfitzenmaier | May 2017 | B2 |
| 11646500 | Glise | May 2023 | B2 |
| 20150102975 | Braubach | Apr 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 2 863 473 | Apr 2015 | EP |
| Entry |
|---|
| International Search Report with English Translation for PCT/EP2022/061499, mailed Jul. 27, 2022, 7 pages. |
| Written Opinion of the ISA for PCT/EP2022/061499, mailed Jul. 27, 2022, 11 pages. |
| International Preliminary Report on Patentability for PCT/EP2022/061499, dated Mar. 28, 2023, 18 pages. |
| Hwu Su et al., “Space station GPS multipath analysis and validation”, Vehicular Technology Conference, Houston, Texas, 49th IEEE, vol. 1, May 16-20, 1999, pp. 757-761. |
| Goncalves Machado Gabriel et al., “Resistively Loaded FSS Clad Thermal Blankets for Enhanced RF Space Communications”, 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, Sep. 9, 2019, pp. 48-52. |
| Number | Date | Country | |
|---|---|---|---|
| 20240266719 A1 | Aug 2024 | US |
