• 专利附录
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    • 专利摘要:
    Circular polarization radiating element, comprising at least one excitation aperture (OE) of a linearly polarized wave according to a first excitation polarization (Ex), a frequency selective surface (S2), a metasurface (S1) comprising a two-dimensional and periodic network of metasurface (MS) cells, the excitation aperture (OE) opening on the metasurface (S1), the metasurface cells (MS) being all oriented identically to the excitation polarization (Ex) and configured to: - reflect an incident wave (Eix) according to the excitation polarization (Ex) to form a reflected wave (Er1x) polarized according to the excitation polarization (Ex), and - depolarize and reflecting the incident wave (Eix) to form a reflected wave (Er1y) polarized according to the orthogonal polarization (Ey) with a phase difference substantially equal to +/- 90 ° with respect to the reflected wave (Er1x) polarized according to the pol excitation arousal (Ex), and with an amplitude substantially equal to the amplitude of a radiated wave (E'tx) by the frequency selective surface (S2), resulting from the reflected wave (Er1x) polarized according to the excitation polarization (Ex).
    公开号:FR3079678A1
    申请号:FR1800260
    申请日:2018-03-29
    公开日:2019-10-04
    发明作者:Herve Legay；Antoine Calleau；Maria Garcia Vigueras；Mauro Ettorre
    申请人:Centre National de la Recherche Scientifique CNRS；Universite de Rennes 1；Thales SA；Institut National des Sciences Appliquees INSA；
    IPC主号:
    专利说明:

    RADIANT ELEMENT WITH CIRCULAR POLARIZATION IMPLEMENTING A RESONANCE IN A CAVITY OF FABRY PEROT
    The invention relates to a radiating element with circular polarization, in particular for a planar antenna, and intended to be used in particular in space communications, on board satellites or in user terminals. The invention also relates to a network antenna comprising at least one such radiating element.
    Different types of radiating elements have recently been developed, responding to the constraints and specificities of space communications.
    The so-called “compact” radiating elements, such as the antennas with resonant cavities from Fabry Perot, make it possible in particular to offer a good compromise between several specifications: good surface efficiency over the entire operating band, sufficient bandwidth for adaptation and in radiation, a small footprint and a low mass. Congestion is particularly critical in the low frequency bands L (1 to 2 GHz), S (2 to 4 GHz), C (from 3.4 to 4.2 GHz in reception and 5.725 and 7.075 GHz in transmission) penalized by significant wavelengths. Also, the search for compact and broadband elements is particularly active for multispot antennas, associating a reflector and a focal network made up of a large number of sources. Fabry Perot's resonant cavity antennas, currently used in space communications, are linearly polarized. Obtaining circular polarization on such antennas must be carried out without degrading the compactness of the radiating element by the addition of a device making it possible to obtain radiation in circular polarization.
    The radiating elements having continuous radiating linear openings, as are for example the quasi-optical beam formers, meanwhile make it possible to radiate several fronts of plane waves over a wide angular sector. They consist of a waveguide with parallel plates ending in a longitudinal horn, which makes the transition between the waveguide with parallel plates and the free space. A focusing / collimating device is inserted on the propagation path of the radiofrequency waves, between the two parallel metal plates, making it possible to convert cylindrical wave fronts coming from the sources into plane wave fronts. These continuous radiating linear apertures operate over a very wide band (for example at 20 and 30 GHz), due to the absence of resonant propagation modes. They are also capable of radiating over a very wide angular sector. However, in their nominal operation, the polarization of the radiated wave is that of the wave which propagates in the waveguide with parallel plates, namely linear.
    In order to obtain identical beam widths according to the two planes, it is also known to widen the continuous radiating linear opening by using a divider with parallel plates. These networks of linear openings also radiate in linear polarization, like each radiating linear opening.
    There is therefore a current need to find devices capable of converting a linear polarization into circular polarization, compatible with existing radiating apertures, and which can also act as a radiating element with circular polarization.
    A first known solution consists in covering the radiating element with a polarizing radome made up of several frequency selective surfaces (FSS), the characteristics of which are optimized so as to generate a phase difference of 90 ° between the two orthogonal polarizations, without disrupt the operation of the antenna. Polarizing radomes cascading quarter-wave layers have good bandwidth performance and oblique incidence, with a thickness (thickness of the order of a wavelength in vacuum) detrimental to the compactness of the antenna. Thin polarizers have also been developed, but their bandwidth and oblique incidence performance are limited.
    A solution consisting in combining a polarizer and a Fabry Perot cavity is found in the document "Self polarizing Fabry-Perot antennas based on polarization twisting element" (SA Muhammad, R. Sauleau, G. Valerio, LL Coq, and H. Legay, IEEE Trans. Antennas Propag., Vol. 61, no. 3, pp. 1032-1040, Mar. 2). The solution is illustrated in Figure 1. The Fabry Perot cavity with frequency selective surfaces radiates similarly in two subspaces (upper and lower). It consists of two partially reflecting periodic surfaces (FSS1, FSS2) according to a linear polarization Ex, and is excited according to this polarization. Periodic surfaces are transparent to the Ey wave. A ground plane with reverse direction of polarization reflects the wave emitted in the lower plane, transforms its linear polarization (for example from Ex to Ey), and returns the wave in the upper direction. This ground plane PM is produced by means of COR corrugations of depth λ / 4, inclined at 45 ° relative to the grids constituting the partially reflecting periodic surfaces (FSS1, FSS2). A distance of λ / 8 (where λ is the wavelength in the radiating element) between the ground plane PM with polarization reversal and the Fabry Perot cavity with partially reflecting periodic surfaces achieves a phase delay of 90 ° on the Ey component, necessary for obtaining circular polarization. Since the cavity is transparent to the Ey component, the field is radiated into the upper subspace. The frequency behavior of this solution is however relatively low band. Indeed, as illustrated in FIG. 4 of the cited document, the rate of ellipticity of the wave at the output of the polarizer is 1 dB over a frequency band corresponding to approximately 2.5% of the central frequency. This low band behavior is linked on the one hand to the PM ground plane corrugations, the height of which (Λ / 4) is a function of the wavelength. It is also linked to the spacing (Λ / 8) between the lower partially reflective periodic surface FSS1 and the ground plane PM, which is a function of the wavelength.
    The invention therefore aims to obtain a radiating element with circular polarization from a linear excitation, both compact in height and very wide band.
    An object of the invention is therefore a radiating element with circular polarization, comprising:
    - at least one excitation opening of a wave linearly polarized according to a first so-called excitation polarization;
    - a frequency selective surface, partially reflecting for the excitation polarization and transparent for a second polarization orthogonal to the excitation polarization, called orthogonal polarization, and to the direction of propagation of the wave, and arranged in a defined plane by the excitation polarization and by the orthogonal polarization;
    the radiating element further comprising a totally reflecting metasurface, facing the frequency selective surface, and comprising a two-dimensional and periodic network of planar conducting elements forming metasurface cells, the excitation opening opening onto the metasurface, the frequency selective surface and the metasurface forming a resonant cavity for the excitation polarization, the metasurface cells being all oriented identically with respect to the excitation polarization and configured for:
    o reflect an incident wave according to the excitation polarization to form a reflected wave polarized according to the excitation polarization, and o depolarize and reflect the incident wave to form a reflected wave polarized according to the orthogonal polarization with a substantially equal phase difference at ± 90 ° from the reflected wave polarized according to the excitation polarization, and with an amplitude substantially equal to the amplitude of a wave radiated by the frequency selective surface, resulting from the reflected wave polarized according to the polarization excitation.
    Advantageously, the metasurface comprises a ground plane on which are disposed a substrate and the network of metasurface cells arranged in rows, the centers of each metasurface cell of the same row being aligned along an alignment axis, the axis of alignment being oriented by an angle of rotation (Ψ) relative to the excitation polarization, the angle of rotation (Ψ) being determined so as to obtain a matrix [S '] of diagonal type, where:
    [S '] = Γ [/ ] [5 ·] [Λ], [S] being the distribution matrix of the metasurface, and [R] a rotation matrix of angle Ψ.
    Advantageously, the metasurface cells of the same row are coupled by an interconnection line with an elongated metasurface along the alignment axis.
    Advantageously, the rows being connected to each other by means of the metasurface cells, forming with the interconnection lines at metasurface a grid pattern with rectangular mesh.
    Alternatively, the metasurface cells in the same row are isolated from each other.
    Advantageously, the metasurface cells of the same row are all spaced periodically.
    Advantageously, all the metasurface cells of the metasurface have the same dimensions.
    Advantageously, the frequency selective surface comprises a network of parallel metallic wires, periodically spaced, and aligned with the excitation polarization.
    Alternatively, the frequency selective surface comprises a two-dimensional network of metal dipoles arranged periodically.
    Advantageously, the excitation opening comprises at least one waveguide opening opening into the resonant cavity.
    Advantageously, the excitation opening comprises a double supply formed by two waveguides opening symmetrically into the resonant cavity, and connected to an impedance matching network.
    Advantageously, the excitation opening is a horn of a radiating linear opening.
    Advantageously, the radiating element comprises a plurality of excitation openings, the excitation openings being formed by a network of linear radiating openings.
    Advantageously, the radiating element at least a second cavity cascaded on the frequency selective surface.
    Advantageously, the metasurface cells are rectangular in shape.
    The invention also relates to a network antenna comprising at least one aforementioned radiating element.
    Other characteristics, details and advantages of the invention will emerge on reading the description given with reference to the accompanying drawings given by way of example and which represent, respectively: FIG. 1, a radiating element with circular polarization of the state art ;
    Figure 2, a schematic representation, in the yz plane, of the radiating element according to the invention, from the ray theory;
    Figure 3, an overview and a detailed view, in the xy plane, of several rows of metasurface cells constituting the metasurface and isolated from each other;
    FIG. 4, a perspective view of the metasurface cells isolated from one another, more particularly illustrating the orientation between the axis of alignment of the metasurface cells with respect to the excitation polarization;
    Figure 5, an overview and a detailed view, in the xy plane, of several rows of metasurface cells constituting the metasurface and connected by an interconnection line;
    Figure 6, a perspective view of the metasurface cells coupled to each other by an interconnection line;
    Figure 7, a perspective view of the metasurface cells forming a rectangular mesh grid;
    Figure 8, an application of the radiating element according to the invention, where the excitation opening is a radiating linear opening horn;
    Figure 9, an application of the radiating element according to the invention, where the excitation openings are radiating linear openings networked;
    FIGS. 10A, 10B and 10C, an embodiment in which the excitation opening comprises a double supply;
    FIGS. 11A and 11B, curves illustrating the directivity and the rate of ellipticity as a function of frequency, for several configurations of radiating elements.
    FIG. 2 illustrates a schematic representation, in the yz plane, of the radiating element according to the invention, from the ray theory. The radiating element includes an excitation opening OE, which leads to a metasurface S1. The metasurface S1 comprises a network of planar conductive elements forming metasurface cells (not shown in FIG. 1), having a certain pattern repeated periodically in two dimensions. Metasurface cells have dimensions smaller than the operating wavelength of the radiating element (so-called "sub-lambda" dimensions).
    A wave linearly polarized according to a first excitation polarization is produced at the level of the excitation opening OE. The excitation opening OE is represented by a rectangular waveguide penetrating into the metasurface S1 without protruding from the metasurface S1, or slightly protruding therefrom. The linearly polarized wave propagates in the cavity, delimited by the metasurface S1 and by a frequency selective surface S2, comprising an arrangement of metal wires or dipoles distributed periodically. The metasurface S1 and the frequency selective surface S2 are spaced from each other by a distance D1. The frequency selective surface S2 is partially reflecting for the excitation polarization Ex (also called TE polarization, for “Transverse Electric”) and transparent for a second polarization Ey orthogonal to the excitation polarization Ex, called orthogonal polarization (also called polarization TM, for “Transverse Magnetic”), and to the direction of propagation of the wave. The frequency selective surface S2 is therefore characterized respectively by reflection and transmission coefficients r 2x and t 2x . The wave produced by the excitation opening is partly radiated (Etx), and partly reflected. This reflected part is called the Eix incident wave.
    The metasurface S1 is completely reflective. It acts in the ground plane, facing the frequency selective surface S2. The metasurface S1 is characterized respectively by the reflection coefficients r lxx and r lyx , which translate the components of the reflected wave according to the polarizations Ex and Ey for the incident wave Eix.
    A resonance is established between the two surfaces for the wave in Ex excitation polarization, typical of Fabry Perot resonators. The incident wave Eix, which propagates in the cavity, undergoes a series of reflections on the selective surface in frequency S2 and on the metasurface S1. At each reflection on the frequency selective surface S2, part of the incident wave Eix is radiated. At each reflection on the metasurface S1, part of the incident wave Eix undergoes a rotation of polarization, also called depolarization, producing the polarized wave Er1y according to the orthogonal polarization Ey. The amplitude of the polarized wave Er1y according to the orthogonal polarization Ey is determined by the reflection coefficient r lyx . Another part of the incident wave Eix retains its polarization, producing the polarized wave Er1x according to the excitation polarization Ex. The amplitude of the polarized wave Er1x according to the excitation polarization Ex is determined by the reflection coefficient r lxx . The synthesis of a radiation in circular polarization is obtained when the radiated wave E'tx by the selective surface in frequency S2, and resulting from the reflected wave Er1x polarized according to the excitation polarization Ex, corresponds in amplitude to l polarized wave Er1y according to the orthogonal polarization Ey, with a phase shift of ± 90 °. The amplitude of the radiated wave E'tx by the frequency selective surface S2 is determined by the transmission coefficient t 2x . The frequency selective surface S2 being transparent to the orthogonal polarization Ey, the polarized wave Er1y according to the orthogonal polarization Ey is radiated without being attenuated. The polarized wave Er1y according to the orthogonal polarization Ey is denoted E'ty. A first radiation in circular polarization is therefore composed of the E'tx and E'ty waves.
    The reflected wave Er1x undergoes a new reflection on the selective surface at frequency S2, with a reflection coefficient r 2x , and, according to the same principle, a second radiation in circular polarization is composed of the waves E ”tx and E” ty, then a third radiation in circular polarization, composed of the waves E '”tx and E” ”ty.
    A beam with circular polarization is thus obtained, more and more attenuated as one moves away from the excitation opening OE.
    A pre-dimensioning of this radiating element can be carried out from the ray theory, traditionally used for this category of radiating element. We suppose that :
    - the cavity size is infinite in the xy plane;
    - the frequency selective surface S2 is characterized respectively by the reflection and transmission coefficients r 2x and t 2x . It is completely transparent to the polarized Ey wave;
    - the distance between the frequency selective surface S2 and the metasurface S1 is equal to D1;
    - the metasurface S1 is respectively characterized by the reflection coefficients r lxx and r lyx translating the components of the reflected wave according to the polarizations Ex and Ey for an incident wave Eix.
    From the above, the transfer functions T x and T y for the polarized transmitted waves E tra ns (x) and E tra ns (y) can be written as being the sum of all the fields transmitted in the far field:
    T x = If ^ l = [Ea + E. u + E tx + ... ] (1) D inc
    Ty = ! ~ i = l E 'cy + E ' y + -] (2) 23 inc
    Where E inc = 1
    From (1) the transfer function T x can be determined:
    T x = t2x + t2 X ri xx r 2x e ~ jko (2D ^ cosW + t2xrlxx 2 r2x 2 e- jk ° ^ D ^ cosW + - (3)
    Where k 0 is the wave number in free space, namely 2π / λ 0 , and θ the angle of incidence of the excitation wave.
    T x = t 2x cos (0) (4) Τχ = lr lxx r 2x e- ^ 2D ^ osW
    From (2), the transfer function T y can be determined:
    T y = r 2x r lyx e ~ ik ° ( ' 2D1 h C0S ^ + r2x 2r ixx r iyxe _7ko (4D1) COS < ' e '> + Ux 3 Mxx yxe ~ 7k o (6D1) cos (0) + ...
    Ty = r lyx r 2x ei k ^ cos ^ Yn = 0 {r Ux r 2x T e - ^ 2n ^ cos ^ (7) _ r iyx r 2x e-> k ^^ y Î-r lxx r 2x e- Jk ^ 2D n cosWW
    The resonance condition is achieved when:
    Zr ixx + ^ r 2x + = 2 / c 0 D 1 cos (0) (9)
    Where xr lxx represents the phase component of the reflection coefficient r lxx , z_r 2x represents the phase component of the reflection coefficient r 2x , and N an arbitrary integer.
    Using the transfer functions calculated in (5) and (8) for the two polarizations, it is possible to calculate the ellipticity rate (AR Axial Ratio) for the entire antenna, using the following relation:
    Jc + VG 2 -4sin 2 (<p)
    AR = 1 (10)
    JG- A / G 2 -4sin 2 (<p)
    Or :
    g = Pl + - (11) φ = ΔΤ χ -ΔΤ γ (12) (13)
    Starting from relations (12) and (13), and using the transfer functions calculated in (5) and (8), it is therefore possible to write the condition to produce pure circular polarization with the following relations:
    | t 2 xl = lr lyx r 2x l (14)
    Zt 2x = Zr lyx + zr 2x - 2 / c o f> i cos (0) + + 2Νπ (15)
    By combining equation (9), describing the resonance condition, and equation (15), describing the circular polarization condition, the following relationship can be obtained:
    2.t 2x ZT y X Zr lxx + ~ + 2 / V 7Γ (16)
    Where N is any integer.
    Equation (16) does not depend on the first order of the frequency (the wave number k 0 is not found in the equation), but only connects the components of the reflection and transmission matrices of the selective surface in frequency S2 and metasurface S1. The bandwidth is no longer limited by the mechanism for generating circular polarization, but by the operating mechanism of the Fabry Pérot cavity. Bandwidth widening techniques for the latter can then be used, without effects on circular polarization. In particular, the cascading of a second cavity, above the frequency selective surface S2, makes it possible to widen the passband, without this degrading the quality of the circular polarization.
    The phase component of the transmission coefficient t 2x of the frequency-selective surface S2 determines the directivity of the radiating element; it is therefore predetermined and known, as a function of the desired directivity. Thus, according to equation (16), to produce pure circular polarization, it is necessary to select the phase components of the reflection coefficients r lyx and r lxx appropriately .
    The distribution matrix [S] (or “scattering matrix” in English terminology) of the metasurface S1 can be written in the classic way in the form:
    L'lyx 'lyyJ
    However, the metasurface S1 does not receive any incidence in orthogonal polarization Ey, insofar as the frequency-selective surface S2 is transparent to the orthogonal polarization. The reflection coefficients r lxy and r lyy , which respectively translate the reflection coefficient in excitation polarization Ex and in orthogonal polarization Ey for an incident wave in orthogonal polarization Ey, are therefore indifferent for the dimensioning of the metasurface S1. Only the reflection coefficients r lxx and r iyx must be taken into account for the dimensioning of the metasurface S1, and determined by the relation (16).
    An Ox'y'z coordinate system is defined as being the result of the rotation of an angle Ψ around the Oz axis of the Oxyz coordinate system (the Ox axis is defined by the excitation polarization Ex, and the Oy axis by orthogonal polarization Ey).
    We therefore seek to obtain, from the distribution matrix [S] in the Oxyz coordinate system, a distribution matrix [S ’] of diagonal type in the Ox’y’z coordinate system, which can be written in the form:
    [S '] = e JiPi. 0 th JÎP2 (17)
    Where the diagonal reflection coefficients e J <P1 and e J <P2 respectively represent the phase components of the waves reflected respectively in excitation polarization and orthogonal polarization, in the frame of reference Ox'y'z. The amplitude components of the waves reflected in excitation polarization and in orthogonal polarization are equal to 1, reflecting the lossless character of the metasurface S1.
    Under normal incidence condition (0 = 0 °), there is thus a congruence relationship between the distribution matrix [S] in the Oxy plane, and the distribution matrix [S '] in the Ox'y' plane, which can therefore be written in the form:
    [S '] = (18)
    Where [Æ] is an angle rotation matrix Ψ:
    ΓΡ1 = cos 5ίη ( ψ ) LJ [—ίίη (Ψ) cos (T)
    It is therefore advisable to identify the angle Ψ which makes it possible to transform the required distribution matrix [S] into a diagonal matrix. For this calculation, which is not detailed here, only the reflection coefficients r lxx and r lyx are specified for the operation of the antenna, the reflection coefficients r lxy and r lyy being only adjustment variables . Thus, once the angle Ψ has been identified to obtain a diagonal matrix, the diagonal reflection coefficients e J <Pi and e j ((> 2 are determined from relations (17) and (18).
    Due to the misalignment of metasurface S1 with respect to the Ex excitation polarization, each incident wave in linear polarization is reflected with a component in Ex excitation polarization and a component in orthogonal polarization Ey. In the case of a metasurface S1 consisting of an arrangement of planar rectangular conducting elements (also called “patches” according to English terminology), the phase responses according to the Ex or Ey polarization are controlled in the first order by the dimensions of the planar conductive element.
    The metasurface S1 can comprise a network of cells with metasurface MS, as illustrated in FIG. 3. The dimensions of the cells with metasurface MS can be obtained in relatively independent ways as a function of the phase components of the diagonal reflection coefficients. Thus, the dimensions of each metasurface cell MS (length ly and width wy) are adjusted as a function of the phase components of the diagonal reflection coefficients e j (P1 and e j <i> 2 determined previously.
    Advantageously, the metasurface cells can be rectangular. The metasurface S1 can therefore be made up of several rows RA of metasurface cells MS.
    As illustrated in FIG. 4, the metasurface cells MS of the same row RA are isolated from each other, and arranged on a SUBI substrate. These elements are arranged between the ground plane crossed by the excitation opening, and the frequency selective surface S2. Each MS metasurface cell therefore forms a dipole, having a mainly capacitive behavior for Ex excitation polarization and for orthogonal Ey polarization. All the CE centers of the MS metasurface cells are aligned along an axis of alignment AX. The alignment axis AX is therefore oriented by the angle Ψ relative to the excitation polarization Ex.
    The MS metasurface cells can all have the same length (dimension ly in FIG. 3), and there can be the same spacing between two MS metasurface cells (dimension px in FIG. 3).
    According to a variant, illustrated in FIG. 5, the metasurface S1 may include interconnection lines with LG metasurface. LG metasurface interconnect lines interconnect all MS metasurface cells in the same RA row. They advantageously make it possible to remove the electrostatic charges present in the MS metasurface cells, and thus improve the overall behavior of the radiating element. MS metasurface cells have remarkably stable incidence properties because particularly small patterns can be used to achieve broadband or even dualband characteristics. MS metasurface cells in the same RA row are orthogonally coupled at their CE center to an LG metasurface interconnect line.
    As illustrated in FIG. 6, the interconnection line with metasurface LG is oriented by the angle Ψ with respect to the excitation polarization Ex. For each row RA, the assembly formed by the interconnection line LG and by cells with metasurface MS therefore constitutes a grid with stubs (or elements of adaptations). The stub grid has a behavior mainly inductive for the polarization of Ex excitation, and capacitive for the orthogonal polarization Ey.
    The frequency selective surface S2, partially reflecting, consists of a network of metal wires F1 spaced periodically, and oriented according to the excitation polarization Ex. As a variant, the frequency selective surface S2 can consist of dipoles, slits or "patches" (or "plaques" in French). The slots can be made in a metal plate, and the patches arranged on an electrically transparent substrate.
    The network of metasurface cells MS is arranged on a SUBI substrate, itself placed on a ground plane PM. The PM ground plane is crossed by the excitation opening OE. The SUBI substrate can for example be composed of two layers of Astroquartz ™, between which is a layer of nidaquartz.
    According to a variant, illustrated in FIG. 7, the rows RA are connected to each other by means of the metasurface cells MS. They thus form with the LG metasurface interconnection lines a rectangular mesh grid pattern. The metasurface S1 thus has an inductive behavior for the Ex excitation polarization and for the orthogonal polarization Ey.
    FIG. 8 illustrates the case where the excitation opening OE is a CRN horn with a radiating linear opening. The radiating linear opening, crossing the metasurface S1 and opening into the cavity, can constitute the radiative part of a quasi-optical beam former, characterized in particular by a wide lateral opening. This solution therefore makes it possible to maintain a wide spectral aperture, while radiating the circular polarization. The larger the size of the radiating linear opening, the smaller the bandwidth in adaptation or radiation. However, this has no influence on the quality of the circular polarization, as indicated in relation (16).
    Figure 9 illustrates the case where there is a plurality of OE excitation openings. The excitation openings OE are formed by a network RES of linear radiating openings, for example from a divider with parallel plates. The use of a divider with parallel plates makes it possible in particular to better distribute the field over the OE excitation openings. In order to limit the couplings between the linear radiating openings, the coupling between the ports should be strongly limited, for example to -15 dB.
    FIGS. 10A, 10B and 10C illustrate an embodiment of the invention, in which the excitation opening OE is split. It includes a double power supply formed by two waveguide openings (WG1, WG2) opening symmetrically into the resonant cavity, and connected to a RAD impedance matching network. The RAD impedance matching network includes at least one IR iris, in order to widen the matching band. This embodiment makes it possible to cancel any parasitic TEM mode present in the radiating element. This TEM mode, which generates cross-polarization lobes, is independent of the OE excitation opening type. FIG. 10C illustrates such an excitation opening, integrated into a radiating element according to the invention. In Figure 10C, each MS metasurface cell forms a dipole, with no interconnection line. The excitation opening can be split in the same way when the MS metasurface cells are connected by an interconnection line, or when they form a rectangular mesh grid.
    FIGS. 11A and 11B illustrate the frequency behavior of the directivity and of the ellipticity rate ("axial ratio" in English terminology), for several antennas integrating the radiating elements in accordance with the invention, and comprising a dual power supply formed by two waveguide openings, in accordance with the embodiment described above. The radiating elements are distinguished by different values of the width (a) and the length (b) of the excitation opening, and for different values of the reflectivity coefficient r 2x . The values of the reflectivity coefficient r 2x are noted “+”, “++” or “+++” to indicate their relative value.
    a (mm) b (mm) Reflectivity of the selective surface in frequency S2 Radiant element 1 5 15 +++ Radiant element 2 5 15 ++ Radiant element 3 10 15 ++ Radiant element 4 10 15 +
    FIG. 11A illustrates the frequency behavior of the directivity of the radiating elements, for an angle 0 = 0 °. The more directional the radiating element (therefore the greater the reflectivity of the frequency-selective surface S2), the less broadband the frequency behavior, which is typical of Fabry Perot cavity antennas. For radiating elements 2, 3 and 4, the bandwidth at -3 dB is around
    10% of the center frequency. FIG. 11B illustrates the frequency behavior of the rate of ellipticity of the radiating elements, for an angle θ = 0 °. The bandwidth at -3 dB is greater than 10% for the four antennas, and remains around 10% at -1 dB, which is clearly superior to the performance of the radiating elements of the state of the art. As demonstrated in relation (16), the technique of generating circular polarization works over a wide bandwidth, and does not limit the operation of the radiating element.
    The broadband behavior can be further improved by cascading a second cavity on the frequency selective surface S2. To achieve this cascading, at least a second resonant cavity is placed on the cavity object of the invention. The second resonant cavity has the frequency-selective surface of the lower cavity as its lower surface, and its partially reflective surface as its upper surface. The cross section of the upper cavity can be larger than that of the first lower, as described in document FR2959611, or, alternatively, have a cross section substantially identical to that of the lower cavity. The embodiment, known as “in bicavity”, makes it possible to lower the reflectivity of the selective surface in frequency of the lower cavity, which favors the broadband behavior of the radiating element, and without however having an influence on the quality of circular polarization.
    权利要求:
    Claims (16)
    [1" id="c-fr-0001]
    1. Radiating element with circular polarization, comprising:
    - at least one excitation opening (OE) of a wave linearly polarized according to a first so-called excitation polarization (Ex);
    - a frequency selective surface (S2), partially reflecting for the excitation polarization (Ex) and transparent for a second polarization (Ey) orthogonal to the excitation polarization (Ex), called orthogonal polarization, and to the direction of propagation of the wave, and arranged in a plane defined by the excitation polarization (Ex) and by the orthogonal polarization (Ey);
    characterized in that it further comprises a metasurface (S1), totally reflecting, facing the frequency selective surface (S2), and comprising a two-dimensional and periodic network of planar conductive elements forming metasurface cells (MS), the excitation opening (OE) leading to the metasurface (S1), the frequency selective surface (S2) and the metasurface (S1) forming a resonant cavity for the excitation polarization (Ex), the cells with metasurface ( MS) being all oriented identically with respect to the excitation polarization (Ex) and configured for:
    o reflect an incident wave (Eix) according to the excitation polarization (Ex) to form a reflected wave (Er1x) polarized according to the excitation polarization (Ex), and o depolarize and reflect the incident wave (Eix) to form a reflected wave (Er1y) polarized according to the orthogonal polarization (Ey) with a phase difference substantially equal to ± 90 ° relative to the reflected wave (Er1x) polarized according to the excitation polarization (Ex), and with an amplitude substantially equal to the amplitude of a radiated wave (E'tx) by the frequency selective surface (S2), resulting from the reflected wave (Er1x) polarized according to the excitation polarization (Ex).
    [2" id="c-fr-0002]
    2. Radiating element according to claim 1, the metasurface (S1) comprising a ground plane (PM) on which are arranged a substrate (SUBI) and the network of metasurface cells (MS) arranged in rows (RA), the centers (CE) of each metasurface cell (MS) of the same row (RA) being aligned along an alignment axis (AX), the alignment axis (AX) being oriented by an angle of rotation (Ψ ) with respect to the excitation polarization (Ex), the angle of rotation (Ψ) being determined so as to obtain a matrix [S '] of diagonal type, where:
    [S '] = ε [Λ] [5 ·] [Λ], [S] being the distribution matrix of the metasurface (S1), and [Æ] a rotation matrix of angle Ψ.
    [3" id="c-fr-0003]
    3. A radiating element according to claim 2, the metasurface cells (MS) of the same row (RA) being coupled by a metasurface interconnection line (LG) elongated along the alignment axis (AX).
    [4" id="c-fr-0004]
    4. A radiating element according to claim 3, the rows (RA) being interconnected by means of metasurface cells (MS), forming with the metasurface interconnection lines (LG) a grid pattern with rectangular mesh.
    [5" id="c-fr-0005]
    5. A radiating element according to claim 2, the metasurface cells (MS) of the same row (RA) being isolated from each other.
    [6" id="c-fr-0006]
    6. Radiating element according to one of claims 2 to 5, the metasurface cells (MS) of the same row (RA) being all spaced periodically.
    [7" id="c-fr-0007]
    7. Radiating element according to one of claims 2 to 6, all metasurface cells (MS) of the metasurface (S1) having the same dimensions.
    [8" id="c-fr-0008]
    8. A radiating element according to one of the preceding claims, the frequency selective surface (S2) comprising a network of metallic wires (Fl) parallel, periodically spaced, and aligned with the excitation polarization (Ex).
    [9" id="c-fr-0009]
    9. Radiating element according to one of claims 1 to 7, the frequency selective surface (S2) comprising a two-dimensional network of metal dipoles arranged periodically.
    [10" id="c-fr-0010]
    10. Radiant element according to one of the preceding claims, the excitation opening (OE) comprising at least one waveguide opening opening into the resonant cavity.
    [11" id="c-fr-0011]
    11. Radiating element according to claim 10, the excitation opening (OE) comprising a double supply formed by two waveguides (WG1, WG2) opening symmetrically in the resonant cavity, and connected to a network of impedance matching (RAD).
    [12" id="c-fr-0012]
    12. Radiating element according to one of claims 1 to 9, the excitation opening (OE) being a horn (CRN) of a radiating linear opening.
    [13" id="c-fr-0013]
    13. Radiating element according to one of claims 1 to 9, comprising a plurality of excitation openings, the excitation openings being formed by a network (RES) of linear radiating openings.
    [14" id="c-fr-0014]
    14. Radiating element according to one of the preceding claims, comprising at least one second cavity cascaded on the frequency selective surface (S2).
    [15" id="c-fr-0015]
    15. Radiating element according to one of the preceding claims, the metasurface cells (MS) being of rectangular shape.
    5
    [0016]
    16. Array antenna comprising at least one radiating element according to one of the preceding claims.
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    同族专利:
    公开号 | 公开日
    US20190305436A1|2019-10-03|
    FR3079678B1|2020-04-17|
    EP3547450B1|2021-10-27|
    CA3038392A1|2019-09-29|
    WO2020109676A2|2020-06-04|
    US11217896B2|2022-01-04|
    EP3547450A1|2019-10-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2011134666A1|2010-04-30|2011-11-03|Thales|Compact radiating element having resonant cavities|
    EP2827444A2|2013-07-18|2015-01-21|ThinKom Solutions, Inc.|Dual-band dichroic polarizer and system including same|
    US3001193A|1956-03-16|1961-09-19|Pierre G Marie|Circularly polarized antenna system|
    EP2266166B1|2008-03-18|2017-11-15|Université Paris Sud |Steerablemicrowave antenna|KR102302466B1|2014-11-11|2021-09-16|주식회사 케이엠더블유|Waveguide slotted array antenna|
    CN112688052A|2019-10-18|2021-04-20|华为技术有限公司|Common-aperture antenna and communication equipment|
    CN110797649B|2019-11-11|2021-08-24|中国电子科技集团公司第十四研究所|Broadband dual-polarization microstrip antenna sub-array with filtering and scaling functions|
    CN110808461B|2019-11-22|2021-11-05|东南大学|Low-profile holographic imaging antenna based on Fabry-Perot resonant cavity type structure|
    CN111129782B|2019-12-31|2021-04-02|哈尔滨工业大学|Double circular polarization three-channel retro-reflector based on super surface|
    CN111900538A|2020-08-17|2020-11-06|上海交通大学|Ka-band satellite communication antenna housing|
    CN112117545B|2020-09-02|2021-08-06|南京航空航天大学|Polarization reconfigurable multifunctional frequency selective wave absorber based on water|
    CN112525095A|2020-11-25|2021-03-19|重庆大学|Method for realizing super-surface biaxial strain sensing by utilizing polarization-phase-deformation relation|
    CN112886272B|2021-01-14|2022-03-04|西安电子科技大学|Dual-frequency dual-polarization Fabry-Perot resonant cavity antenna|
    法律状态:
    2019-03-05| PLFP| Fee payment|Year of fee payment: 2 |
    2019-10-04| PLSC| Publication of the preliminary search report|Effective date: 20191004 |
    2020-02-27| PLFP| Fee payment|Year of fee payment: 3 |
    2021-02-25| PLFP| Fee payment|Year of fee payment: 4 |
    2022-02-21| PLFP| Fee payment|Year of fee payment: 5 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1800260A|FR3079678B1|2018-03-29|2018-03-29|RADIANT ELEMENT WITH CIRCULAR POLARIZATION IMPLEMENTING A RESONANCE IN A CAVITY OF FABRY PEROT|
    FR1800260|2018-03-29|FR1800260A| FR3079678B1|2018-03-29|2018-03-29|RADIANT ELEMENT WITH CIRCULAR POLARIZATION IMPLEMENTING A RESONANCE IN A CAVITY OF FABRY PEROT|
    EP19165394.8A| EP3547450B1|2018-03-29|2019-03-27|Radiating element with circular polarisation implementing a resonance in a fabry-perot cavity|
    US16/367,085| US11217896B2|2018-03-29|2019-03-27|Circularly polarised radiating element making use of a resonance in a Fabry-Perot cavity|
    CA3038392A| CA3038392A1|2018-03-29|2019-03-29|Circularly polarised radiating element making use of a resonance in a fabry-perot cavity|
    PCT/FR2019/000145| WO2020109676A2|2018-03-29|2019-09-13|Equilibrium of radiating energies in the magnetic domain|
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