Abstract:
An antenna structure for telecommunications is provided. The antenna structure may be particularly for satellite telecommunications. The antenna structure includes an emitting surface including at least one set of a plurality of elementary emitting antennas forming an array, at least one elementary emitting antenna including two generally circular patches that are at least partially superimposed, the at least one elementary emitting antenna being dimensioned to emit at least one electromagnetic wave having a frequency between 27 gigahertz and 31 GHz.

Description:
[0001]    Priority is hereby claimed to FR 13 03086 filed on Dec. 26, 2013, the entire disclosure of which is hereby incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an elementary antenna, a compact antenna structure for telecommunications comprising such an antenna, a platform comprising the antenna structure and a satellite communication method between two stations using the antenna structure. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the field of satellite communications, obtaining a high-quality communication involves particular performance for the electromagnetic waves produced by the antenna structure used in the communication in terms of gain and secondary lobe level (ratio between the intensity of the secondary lobes and the intensity of the primary lobe). This is even more true for so-called “broadband” satellite communications, i.e., not emitting only voice. 
         [0004]    In the particular case of the Ka electromagnetic band, two separate frequency bands are involved. In fact, in emitting, the electromagnetic waves of the Ka band have a frequency comprised between 27 gigahertz (GHz) and 31 GHz, while in receiving, the electric waves of the Ka band have a frequency comprised between 17.3 GHz and 21.2 GHz. In the rest of the description, the Ka band for emitting is denoted Tx, while the Ka band for receiving is denoted Rx. Furthermore, the polarizations of the emitting and receiving waves are generally of the circular type, and may or may not be opposite. 
         [0005]    These frequencies and these circular polarizations in receiving and emitting impose constraints on the antenna structure. Furthermore, in the context of satellite connections, the antenna should be oriented so as to aim at the satellite making it possible to establish the connection. Furthermore, to reduce the visual signature (physical bulk), parabolic antenna-type solutions are generally not favored. This is particularly true given that in that case, the depth of the antenna is constrained by the focal distance of the source illuminating the satellite dish. 
         [0006]    Among the antenna structures making it possible to respect these various constraints, it is known to use an electronically-scanned antenna for the emitting of a wave whose central frequency is around 30 GHz and for the receiving of a wave centered around 20 GHz. 
         [0007]    However, the electronically-scanned antenna obtained may have a significant bulk corresponding to the radiating surfaces of each of the operating modes (emitting/receiving). Furthermore, the efficiency of such an antenna may be insufficient based on the elementary antenna used and the associated power circuit, in particular when patch-type antennas are involved. 
         [0008]    Furthermore, the implementation of a circular polarization in a first direction in the emitting part and a circular polarization in a second direction that may or may not be opposite the first direction for the receiving part proves difficult if a polarizer is used, which reduces the usage flexibility of the considered scanning antenna. 
       SUMMARY OF THE INVENTION 
       [0009]    There is therefore a need for an antenna structure for telecommunications, in particular satellite in the Ka band, having a reduced bulk in terms of depth and aiming capacity while using an electronic scanning principle while also making it possible to obtain a good quality communication, in particular in terms of gain, axial ratio and secondary lobes compatible with normative templates. 
         [0010]    The present invention provides, an antenna structure for telecommunications, in particular by satellite, comprising an emitting surface comprising at least one set of a plurality of elementary emitting antennas forming an array, at least one elementary emitting antenna comprising two generally circular patches that are at least partially superimposed, said at least one elementary emitting antenna being dimensioned to emit at least one electromagnetic wave having a frequency comprised between 27 gigahertz (GHz) and 31 GHz. The antenna structure also comprises a receiving surface comprising at least one set of a plurality of elementary receiving antennas forming an array, at least one elementary receiving antenna comprising two generally circular patches that are at least partially superimposed, said at least one elementary receiving antenna being dimensioned to receive at least one electromagnetic wave having a frequency comprised between 17.3 GHz and 21.2 GHz. 
         [0011]    According to specific embodiments, the antenna structure may include one or more of the following features considered alone or according to all technically possible combinations:
       each patch of said at least one elementary emitting antenna has a center, said elementary emitting antenna comprising two power supply ports able to power one of the two patches, each port being in an angular sector having an angle relative to the center of the powered patch smaller than 180°, and/or each patch of said at least one elementary receiving antenna has a center, said elementary receiving antenna comprising two power supply ports able to power one of the two patches, each port being in an angular sector having an angle relative to the center of the powered patch smaller than 180°.   the two patches of said at least one elementary emitting antenna are spaced apart in a first direction by a distance comprised between 0.5 millimeters (mm) and 2.0 mm, and/or the two patches of said at least one elementary receiving antenna are spaced apart in a first direction by a distance comprised between 0.5 millimeters (mm) and 2.0 mm.   the two patches of said at least one elementary emitting antenna are spaced apart in a first direction by a distance comprised between 0.75 millimeters (mm) and 1.5 mm, and/or the two patches of said at least one elementary receiving antenna are spaced apart in a first direction by a distance comprised between 0.75 millimeters (mm) and 1.5 mm.   the diameters of the two patches of said at least one elementary emitting antenna are identical, and/or the diameters of the two patches of said at least one elementary receiving antenna are identical.   the elementary emitting antennas of the antenna structure all comprise two generally circular patches that are at least partially superimposed, each elementary emitting antenna being dimensioned to emitemit at least one electromagnetic wave having a frequency comprised between 27 GHz and 31 GHz, and/or the elementary receiving antennas of the antenna structure all comprise two generally circular patches that are at least partially superimposed, each elementary receiving antenna being dimensioned to receive at least one electromagnetic wave having a frequency comprised between 17.3 GHz and 21.2 GHz.   the elementary emitting antennas and the elementary receiving antennas are arranged in staggered rows.   the emitting surface is generally rectangular and comprises at least two sets of a plurality of elementary emitting antennas each forming an array, the elementary emitting antennas of each set being along a line specific to that set, each line being parallel to the other specific lines, and/or the receiving surface is generally rectangular and comprises at least two sets of a plurality of elementary receiving antennas each forming an array, the elementary receiving antennas of each set being along a line specific to that set, each line being parallel to the other specific lines.       
 
         [0019]    Furthermore, the invention provides a platform, in particular aerial, comprising at least one antenna structure as previously described. 
         [0020]    The present invention also provides a telecommunications method, in particular by satellite, between two stations comprising at least one of the following steps: a step for emitting electromagnetic waves having a frequency comprised between 27 GHz and 31 GHz by an antenna structure as previously described, and a step for receiving electromagnetic waves having a frequency comprised between 17.3 GHz and 21.2 GHz by an antenna structure as previously described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Other features and advantages of the invention will appear upon reading the following detailed description of embodiments of the invention, provided solely as an example and in reference to the drawings: 
           [0022]      FIG. 1  is a diagram of an antenna structure able to work on the Ka band, 
           [0023]      FIG. 2  is a perspective diagram of an elementary antenna working on the Tx band, 
           [0024]      FIGS. 3 and 4  are graphs respectively showing the evolution of the axial ratio and the stationary wave ratio of the elementary antenna of  FIG. 2  on the Tx band as a function of the operating frequency, 
           [0025]      FIG. 5  is a diagram of an array comprising a set of elementary antennas according to  FIG. 2 , 
           [0026]      FIGS. 6 and 7  are graphs showing the evolution of the axial ratio and the stationary wave ratio of the array of  FIG. 5  as a function of the operating frequency, 
           [0027]      FIG. 8  is a graph showing the evolution of the gain of the antenna structure according to  FIG. 5  as a function of the elevation angle, 
           [0028]      FIG. 9  is a diagram of a panel working on the Tx band and comprising arrays according to  FIG. 5 ; 
           [0029]      FIGS. 10 and 11  are graphs showing the evolution of the gain of the panel of  FIG. 9  as a function of the elevation angle and for a given azimuth angle, 
           [0030]      FIG. 12  is a graph showing the evolution of the axial ratio of the panel of  FIG. 9  as a function of the operating frequency, 
           [0031]      FIG. 13  is a graph showing the evolution of the gain of the panel of  FIG. 9  as a function of the azimuth angle when a misalignment is implemented, 
           [0032]      FIG. 14  is a perspective diagram of an elementary antenna operating on the Rx band, 
           [0033]      FIGS. 15 and 16  are graphs showing the evolution of the axial ratio and the stationary wave ratio for the elementary antenna of  FIG. 14  on the Rx band as a function of the operating frequency, 
           [0034]      FIG. 17  is a diagram of an array comprising a set of elementary antennas according to  FIG. 14 , 
           [0035]      FIGS. 18 and 19  are graphs showing the evolution of the axial ratio and the stationary wave ratio of the array of  FIG. 17  as a function of the operating frequency, 
           [0036]      FIG. 20  is a graph showing the evolution of the gain of the array of  FIG. 17  as a function of the elevation angle, 
           [0037]      FIG. 21  is a diagram of a panel working on the Rx band and comprising arrays according to  FIG. 17 ; 
           [0038]      FIGS. 22 and 23  are graphs showing the evolution of the gain of the panel of  FIG. 21  as a function of the elevation angle and the azimuth angle, respectively, and 
           [0039]      FIG. 24  is a graph showing the evolution of the axial ratio of the panel of  FIG. 21  as a function of the operating frequency. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    In the context of an application in telecommunications, in particular by satellite in the Ka band, an antenna structure  10  is proposed comprising an emitting surface  11   Tx  and a receiving surface  11   Rx  as shown in  FIG. 1 . 
         [0041]    In the illustrated example, the emitting surface  11   Tx  has a generally rectangular shape and the receiving surface  11   Rx  also has a generally rectangular shape. Each emitting  11   Tx  and receiving  11   Rx  surface receives a plurality of elementary antennas  12   Tx  (for emitting) and  12   Rx  (for receiving). 
         [0042]    The assembly of the emitting surface  11   Tx  and the plurality of elementary antennas  12   Tx  forms an emitting panel  13   Tx , while the assembly of the receiving surface  11   Rx  and the plurality of elementary antennas  12   Rx  forms a receiving panel  13   Rx.    
         [0043]    Hereinafter, the structure of the emitting panel  13   Tx  is outlined by successively describing an elementary antenna  12   Tx  for emitting ( FIGS. 2 to 4 ), a line comprising a plurality of elementary antennas  12   Tx  for emitting ( FIGS. 5 to 8 ), then the emitting panel  13   Tx  itself ( FIGS. 9 to 13 ). An elementary antenna  12   Tx  for emitting is shown in  FIG. 2 . This means that the elementary antenna  12   Tx  is able to emit an electromagnetic wave whereof the wavelength is denoted λ0, that wavelength λ0 corresponding to a central frequency of the band comprised between 27 GHz and 31 GHz. 
         [0044]    The elementary antenna  12   Tx  comprises two patches  14   Tx ,  16   Tx  that are at least partially superimposed. 
         [0045]    Each patch  14   Tx ,  16   Tx  has a circular shape. 
         [0046]    The first patch  14   Tx  comprises a first metallized layer  18   Tx  and a first insulating layer  20   Tx , the first metallized layer  18   Tx  being arranged on the insulating layer  20   Tx.    
         [0047]    The first metallized layer  18   Tx  is therefore circular and has a first diameter d 1   Tx.    
         [0048]    The shape of the first metallized layer  18   Tx  gives the first patch  14   Tx  a circular shape. 
         [0049]    The second patch  16   Tx  also comprises a second metallized layer  22   Tx  and a second insulating layer  24   Tx , the second metallized layer  22   Tx  being arranged on the second insulating layer  24   Tx.    
         [0050]    The second metallized layer  22   Tx  comprises a circular part  26   Tx  and two ports  28   Tx ,  30   Tx  for supplying current. 
         [0051]    The circular part  26   Tx  has a circular shape and has a second diameter denoted d 2   Tx . The first port  28   Tx  comprises two first segments  32   Tx  and  34   Tx , a first proximal segment  32   Tx  in contact with the circular part  26   Tx  and a first distal segment  34   Tx  relative to the circular part  26   Tx.    
         [0052]    The first proximal segment  32   Tx  is rectilinear and extends in a direction called first proximal direction. The first proximal segment  32   Tx  is normal relative to the portion of the circular part  26   Tx  with which the first proximal segment  32   Tx  is in contact. 
         [0053]    The first distal segment  34   Tx  is rectilinear and extends in the extension of the proximal segment  32   Tx  in a direction called first distal direction. The first proximal and distal directions form an angle greater than 90° between them. Preferably, the angle between the first proximal direction and the first distal direction is comprised between 120° and 145°. 
         [0054]    Likewise, the second port  30   Tx  comprises two second segments  38   Tx  and  40   Tx , a second proximal segment  38   Tx  in contact with the circular part  26   Tx  and a second distal segment  40   Tx  relative to the circular part  26   Tx.    
         [0055]    The second proximal segment  38   Tx  is rectilinear and extends in a direction called second proximal direction. The second proximal segment  38   Tx  is normal relative to the portion of the circular part  26   Tx  with which the second proximal segment  38   Tx  is in contact. 
         [0056]    According to the example of  FIG. 2 , the two proximal directions form an angle smaller than 180° between them. Thus, each port  28   Tx ,  30   Tx  is in an angular sector having an angle relative to the center of the circular part smaller than 180°. 
         [0057]    In other words, the distance between the two ports  28   Tx  and  30   Tx  is smaller than 0.5*λ0 to make it possible to perform the aiming function by phase shift with the smallest possible deterioration of the secondary lobes in order to remain compatible with normalization templates. Preferably, the distance between the two ports  28   Tx  and  30   Tx  is smaller than or equal to 0.42*λ0. 
         [0058]    The second distal segment  40   Tx  is rectilinear and extends in the extension of the second proximal segment  38   Tx  in a direction called second distal direction. The second proximal and distal directions form an angle greater than 90° between them. Preferably, the angle between the second proximal direction and the second distal direction is comprised between 120° and 145°. 
         [0059]    The shape of the second metallized layer  22   Tx  gives the second patch  16   Tx  a generally circular shape such that it is considered, in a simplified manner hereinafter, that the second patch  16   Tx  has a circular shape. 
         [0060]    Thus, it is in particular considered that the second diameter d 2   Tx  of the circular part  26   Tx  is the diameter of the second patch  16   Tx.    
         [0061]    Preferably, the first diameter d 1   Tx  and the second diameter d 2   Tx  can be identical. 
         [0062]    The two patches  14   Tx  and  16   Tx  are at least partially superimposed. This means that the two patches  14   Tx  and  16   Tx  are at least partially aligned in a first direction Z. 
         [0063]    According to the particular example of  FIG. 2 , two patches  14   Tx  and  16   Tx  are superimposed. This means that the projection of the circular part  26   Tx  on the plane comprising the first metallized layer  18   Tx  is combined with the first metallized layer  18   Tx.    
         [0064]    Furthermore, the circular part  26   Tx  and the first metallized layer  18   Tx  are parallel. The two patches  14   Tx  and  16   Tx  are thus spaced apart in a first direction Z by a distance denoted ezTx. 
         [0065]    Preferably, the spacing distance ezTx between the two patches  14   Tx  and  16   Tx  in the first direction Z is comprised between 0.5 millimeters (mm) and 2.0 mm. Advantageously, the spacing distance ezTx between the two patches  14   Tx  and  16   Tx  in the first direction Z is comprised between 0.75 mm and 1.5 mm. 
         [0066]    In a manner known in itself, the spacing distance ezTx between the two patches  14   Tx  and  16   Tx  in the first direction Z, the diameter d 1   Tx  and d 2   Tx  of the patches  14   Tx  and  16   Tx  make it possible to determine the frequency or frequencies at which the elementary antenna  12   Tx  can emit. 
         [0067]    The elementary antenna  12   Tx  is dimensioned to emit frequencies comprised between 27 GHz and 31 GHz (Tx band). This means that such an elementary antenna  12   Tx  has first and second diameters d 1   Tx , d 2   Tx  comprised between 2.5 mm and 4 mm. The upper bound corresponds to the product of 0.4 by the wavelength a that the elementary antenna  12   Tx  is capable of emitting. 
         [0068]    Alternatively, instead of a condition on the diameters d 1   Tx , d 2   Tx , a constraint is imposed on the geometry of the second patch  16   Tx . The second patch  16   Tx  can be fitted into a rectangle whereof the extension exTx in a second direction X is comprised between 4.0 mm and 4.4 mm, and the extension eyTx in a third direction Y is comprised between 3.8 mm and 4.2 mm. The two directions X and Y are perpendicular to each other and to the first direction Z. 
         [0069]    The performance of the elementary emitting antenna  12   Tx  will now be described in reference to  FIGS. 3 and 4 . 
         [0070]      FIGS. 3 and 4  show that over the entire band of interest (in this case, the Tx band), the axial ratio and the stationary wave ratio (denoted using the corresponding acronym, SWR, in all of the figures in which this ratio appears for simplification purposes) are relatively low. 
         [0071]    The elementary antenna  12   Tx  therefore has a wide band, i.e., a band 5% wider around the central operating frequency, with circular polarization and a very good efficiency of illumination (in particular the axial ratio for such a small antenna is better than in the state of the art and the apodization of the radiation pattern for the emitted wave is facilitated during networking). 
         [0072]    It should be noted that in the illustrated embodiment, the two patches  14   Tx  and  16   Tx  are arranged such that the second metallic layer  22   Tx  faces the first insulating layer  20   Tx.    
         [0073]    Alternatively, the two patches  14   Tx  and  16   Tx  are arranged such that the second metallic layer  22   Tx  faces the first metallic layer  18   Tx.    
         [0074]    An array  50   Tx  has also been proposed as illustrated by  FIG. 5 , comprising a plurality of elementary antenna  12   Tx  for emitting. 
         [0075]    According to the particular example of  FIG. 5 , the array  50   Tx  comprises twenty-four elementary antennas  12   Tx.    
         [0076]    In general, a combination of a larger number of elementary antennas  12   Tx  is possible based on the overall dimensions and desired performance, in particular in terms of the gain of the array  50   Tx.    
         [0077]    Each elementary antenna  12   Tx  of  FIG. 5  is identical to the elementary antenna  12   Tx  described in reference to  FIG. 2 . 
         [0078]    Alternatively, some antennas are different. 
         [0079]    The elementary antennas  12   Tx  are arranged regularly along a line thus forming the array  50   Tx . Furthermore, the elementary antennas  12   Tx  are connected to each other to form the array  50   Tx . The connection is done by means of two rectilinear lines that ensure the power supply of the unit array. The array  50   Tx  thus formed for emitting has two ports that make it possible, based on the power supply, to radiate an electromagnetic wave in the desired frequency band using the desired circular polarization. 
         [0080]    In the example of  FIG. 5 , the array  50   Tx  has an extension ex 2   Tx  along the second direction X comprised between 4 mm and 6 mm. Preferably, the extension ex 2   Tx  in the second direction X is comprised between 4.5 mm and 5.5 mm. 
         [0081]    In the example of  FIG. 5 , the array  50   Tx  also has an extension ey 2   Tx  in the third direction Y comprised between 160 mm and 190 mm. Preferably, the extension ey 2   Tx  in the third direction Y is comprised between 165 mm and 185 mm. 
         [0082]    During operation, each elementary antenna  12   Tx  of the array  50   Tx  is powered by an electromagnetic wave. Each elementary antenna  12   Tx  captures the electrical field coming from electromagnetic wave so that the array  50   Tx  emits a wave in the desired frequency band. 
         [0083]    The performance in terms of axial ratio and stationary wave ratio and advantages imparted by the array  50   Tx  are similar to the performance and advantages imparted by the elementary antennas  12   Tx  of  FIG. 2  as shown by studying  FIGS. 6 and 7 . 
         [0084]    Furthermore,  FIG. 8  shows that the array  50   Tx  has a gain of approximately 20 dB, which attests to the good efficiency of illumination of the antenna structure in light of its dimensions, i.e., the extension ex 2   Tx  in the second direction X and the extension ey 2   Tx  in the third direction Y. 
         [0085]      FIG. 9  illustrates the emitting panel  13   Tx  of  FIG. 1 . The elements identical to the embodiment of  FIG. 5  are not described again. Only the differences are shown. 
         [0086]    The emitting panel  13   Tx  comprises eight arrays  50   Tx  instead of a single array  50   Tx.    
         [0087]    In general, a combination of a larger number of arrays  50   Tx  is possible based on the overall dimensions and desired performance in particular in terms of gain and radiation opening. 
         [0088]    In the case at hand, the number of antennas for the array  50   Tx  is chosen as a function of a dimensional constraint applied in the third direction Y. 
         [0089]    Each array  50   Tx  is parallel to the other arrays  50   Tx.    
         [0090]    The elementary antennas  12   Tx  are arranged in staggered rows. Such an arrangement makes it possible to preserve the performance in terms of stability of the axial ratio during networking of the overall structure as well as during aiming by phase shift. 
         [0091]    Furthermore, in the example of  FIG. 9 , the emitting panel  13   Tx  has an extension ex 3   Tx  in the second direction X comprised between 40 mm and 50 mm. Preferably, the extension ex 3   Tx  in the second direction X is comprised between 45 mm and 48 mm. The extension ex 3   Tx  in the second direction X is connected to the number of array antennas  50   Tx  in question. In the case shown in  FIG. 9 , the extension ex 3   Tx  in the second direction X corresponds to approximately nine times the size of an elementary antenna. 
         [0092]    In the example of  FIG. 9 , the emitting panel  13   Tx  also has an extension ey 3   Tx  in the third direction Y comprised between 160 mm and 190 mm. Preferably, the extension ey 3   Tx  in the third direction Y is comprised between 165 mm and 185 mm. The extension ey 3   Tx  in the third direction Y is related to the number of elementary antennas  12   Tx  in question. 
         [0093]    The performance in terms of axial ratio and advantages imparted by the emitting panel  13   Tx  are similar to the performance and advantages imparted by the elementary antenna  12   Tx  of  FIG. 2 , as shown by studying  FIG. 12 . 
         [0094]    Furthermore,  FIGS. 10 and 11  show that the emitting panel  13   Tx  has a gain of approximately 28 dB, which corresponds to an efficient compact antenna structure at the considered operating frequency. 
         [0095]    Furthermore, when a misalignment is done, it can be shown by comparing  FIGS. 11 and 13  in particular that the gain of 26 dB is obtained in a relatively remote direction determined by an azimuth angle of 30°. The proposed emitting panel  13   Tx  is therefore robust with respect to misalignment with a very low rise of the secondary lobes. 
         [0096]    Below, the structure of the receiving panel  13   Rx  of  FIG. 1  is outlined by successively describing an elementary antenna  12   Rx  for receiving ( FIGS. 14 to 16 ), a line comprising a plurality of elementary antennas  12   Rx  for receiving ( FIGS. 17 to 20 ), then the receiving panel  13   Rx  itself ( FIGS. 21 to 24 ). 
         [0097]      FIG. 14  illustrates an elementary antenna  12   Rx  for receiving. The elements identical to the elementary emitting antenna  12   Tx  of  FIG. 2  are not described again. Only the differences are shown. 
         [0098]    The reference signs of the elements of the elementary receiving antenna  12   Rx  are followed by an Rx suffix instead of the Tx suffix for the corresponding elements of the elementary antenna  12   Rx.    
         [0099]    An elementary antenna  12   Rx  for receiving is shown in  FIG. 14 . This means that the elementary antenna  12   Rx  is able to receive an electromagnetic wave whose wavelength is denoted λ0, that wavelength λ0 corresponding to a frequency comprised between 17.3 GHz and 21.2 GHz. 
         [0100]    Consequently, the elementary antenna  12   Rx  is dimensioned to receive frequencies comprised between 17.3 GHz and 21.2 GHz (Rx band). This means that such an elementary antenna  12   Rx  has first and second diameters d 1   Rx , d 2   Rx  comprised between 4.5 mm and 7 mm. 
         [0101]    Alternatively, instead of a condition on the diameters d 1   Rx , d 2   Rx , a constraint is imposed on the second patch  16   Rx . The second patch  16   Rx  can then be fitted into a rectangle whereof the extension exRx in the second direction X is comprised between 6.6 mm and 7.0 mm and the extension eyRx in the third direction Y is comprised between 6.0 mm and 6.4 mm. 
         [0102]    The receiving performance of the elementary antenna  12   Rx  will now be described in reference to  FIGS. 15 and 16 . 
         [0103]    The performance and advantages imparted by the elementary receiving antenna  12   Rx  are similar to the performance and advantages imparted by the elementary emitting antenna  12   Tx , as shown by studying  FIGS. 15 and 16 . 
         [0104]      FIG. 17  illustrates an array  50   Rx  for receiving according to the invention. According to the specific example of  FIG. 17 , the array  50   Rx  comprises eighteen elementary antennas  12   Rx.    
         [0105]    In general, a combination of a larger number of elementary antennas  12   Rx  is possible based on the overall dimensions and desired performance, in particular in terms of the gain of the array  50   Rx.    
         [0106]    In the case at hand, the number of antennas for the array  50   Rx  is chosen as a function of a dimensional constraint applied in the third direction Y. 
         [0107]    Each elementary antenna  12   Rx  of  FIG. 17  is identical to the elementary antenna  12   Rx  described in reference to  FIG. 14 . 
         [0108]    Alternatively, some antennas are different. 
         [0109]    The elementary antennas  12   Rx  are arranged regularly along a line thus forming the array  50   Rx . Furthermore, the elementary antennas  12   Rx  are connected to each other to form the array  50   Rx . The connection is done by means of a rectilinear line that ensures the power supply of the unit array. The array  50   Rx  thus formed for receiving has two ports that make it possible, based on the power supply, to receive an electromagnetic wave in the desired frequency band using the desired circular polarization. 
         [0110]    In the example of  FIG. 17 , the array  50   Rx  has an extension ex 2   Rx  in the second direction X comprised between 6 mm and 8.5 mm. Preferably, the extension ex 2   Rx  in the second direction X is comprised between 7.6 mm and 8.0 mm. 
         [0111]    In the example of  FIG. 17 , the array  50   Rx  also has an extension ey 2   Rx  in the third direction Y comprised between 180 mm and 200 mm. Preferably, the extension ey 2   Rx  in the third direction Y is comprised between 185 mm and 195 mm. The extension ey 2   Rx  in the third direction Y is related to the number of elementary antennas  12   Rx  in question. 
         [0112]    The performance in terms of axial ratio and stationary wave ratio and advantages imparted by the array  50   Rx  are similar to the performance and advantages imparted by the elementary antennas  12   Rx  according to the example of  FIG. 14  as shown by studying  FIGS. 18 and 19 . 
         [0113]    Furthermore,  FIG. 20  shows that the array  50   Rx  has a gain of approximately 18 dB, which corresponds to an efficient compact antenna structure at the considered operating frequency. 
         [0114]      FIG. 21  illustrates the receiving panel  13   Rx  of  FIG. 1 . The elements identical to the embodiment of  FIG. 17  are not described again. Only the differences are shown. 
         [0115]    The receiving panel  13   Rx  comprises eight arrays  50   Rx  instead of a single array  50   Rx.    
         [0116]    In general, a combination of a larger number of arrays  50   Rx  is possible based on the overall dimensions and desired performance in particular in terms of gain and radiation opening. 
         [0117]    Each array  50   Rx  is parallel to the other arrays  50   Rx.    
         [0118]    The elementary antennas  12   Rx  are arranged in staggered rows. Such an arrangement makes it possible to preserve the performance in terms of stability of the axial ratio during networking of the overall structure as well as aiming by phase shift. 
         [0119]    Furthermore, in the example of  FIG. 21 , the receiving panel  13   Rx  has an extension ex 3   Rx  in the second direction X comprised between 60 mm and 80 mm. Preferably, the extension ex 3   Rx  in the second direction X is comprised between 65 mm and 75 mm. The extension ex 3   Rx  in the second direction X is related to the number of arrays  50   Rx  in question. 
         [0120]    In the example of  FIG. 21 , the receiving panel  13   Rx  also has an extension ey 3   Rx  in the third direction Y comprised between 190 mm and 210 mm. Preferably, the extension ey 3   Rx  in the third direction Y is comprised between 195 mm and 205 mm. The extension ey 3   Rx  in the third direction Y is related to the number of elementary antennas  12   Tx  in question. 
         [0121]    The performance in terms of axial ratio and gain and advantages imparted by the receiving panel  13   Rx  are similar to the performance and advantages imparted by the panel  50   Rx  of  FIG. 17 , as shown by studying  FIGS. 22 to 24 . 
         [0122]    In all of the embodiments, because the elementary antenna  12  has a wide band, circular polarization and good efficiency of illumination, the antenna structure  10  has a reduced bulk and a reduced weight relative to the antenna structures of the state of the art for identical radiation performance. This reduced weight makes it possible to reduce the constraints in particular in the case where the entire antenna is accompanied by a mechanical positioner. 
         [0123]    Furthermore, the production of this antenna structure  10  on a single-layer substrate makes it possible to insert easily, on the rear side at the ground plane, with the least amount of stress and impact on the radiation performance, the coupler, power supply and phase shift devices to ensure monitoring and polarization choice as well as phase law and amplitude making it possible to orient the radiation pattern in the desired direction in the electronic scanning configuration. 
         [0124]    The antenna structure  10  is also capable of emitting or receiving circularly polarized electromagnetic waves without using an additional polarizer. This better compactness is accompanied by improved lightness and improved radiation performance over a wide frequency band compatible with the targeted application. Furthermore, the antenna structure  10  is easy to produce and can be manufactured at a low cost. 
         [0125]    Thus, the proposed antenna structure  10  is usable for telecommunications applications between two stations, in particular by satellite. It should be noted that in that case, the radiation pattern of the antenna structure  10  thus produced complies with the templates specified to be used with certain satellites. 
         [0126]    Such an antenna structure  10  can advantageously be used in a platform, in particular aerial of the helicopter or drone type. In the context of that use, the compactness of the antenna structure  10  makes it possible to reduce the constraints on installations of equipment in the platform. 
         [0127]    The antenna structure  10  described in reference to  FIG. 1  is an example of an antenna structure  10  having the compactness properties previously described. Other similar antenna structures  10  can also be considered, in particular with a different number of elementary receiving  12   Rx  and/or emitting  12   Tx  antennas and a different arrangement thereof. 
         [0128]    These different antenna structures  10  are antenna structures for telecommunications, in particular by satellite, having a reduced bulk in terms of depth and aiming capacities using an electronic scanning principle while making it possible to obtain a high-quality high-bandwidth communication, in particular in terms of gain, axial ratio and secondary lobes compatible with normative templates.