FR2700067A1 - Dual polarized plated antenna and corresponding transmitting / receiving device. - Google Patents

Abstract

The invention relates to a plated antenna, of the type comprising at least one radiating element generating two microwave waves with distinct linear polarizations. According to the invention, the radiating element or elements (11, 12) are supplied on the one hand, through a first slot (15), by a first supply line (13), and on the other hand, through a second (16) and a third (17) slits, via a second supply line (14), the second and third slits (16, 17) being of the same length (L2) and parallel to each other. Each radiating element (11, 12) resonates on the one hand along a first resonance axis (116) perpendicular to the axis (117) of the first slot (15) and on the other hand along a second resonance axis (118 ) perpendicular to the axis (119) of the second and third slot (16, 17), the intersection of these two resonance axes (116, 118) being at a right angle and defining a resonance center (120). The first slot (15) is centered transversely with respect to said first axis of resonance (116) and longitudinally with respect to said center of resonance (120). The second (16) and third (17) slits are centered transversely with respect to said second resonance axis (118) and placed equidistant from said resonance center (120).

Description

Dual polarized plated antenna and transmitting / receiving device

  corresponding. The field of the invention is that of antennas made in printed technology and working in frequency reuse by polarization diversity. More specifically, the invention relates to a dual polarization plated antenna, of the type comprising two radiating elements both participating in the generation of two microwave waves with distinct linear polarizations, each radiating element being fed through at least two cut-out slots. in a plane of mass, by two power supplies each corresponding to one of the

two distinct polarizations.

  This type of antennas is of great interest for the realization of networks

  electronically controlled antennas.

  The invention has many applications, such as for example the production of antennas to be embedded on a satellite. In this case,

  Frequency reuse makes it possible to significantly reduce the clutter

  spectral effect of the antennas used.

  The most conventional power supply techniques for printed antennas, whether using a direct contact microstrip line or a coaxial probe, do not make it possible to obtain a large bandwidth with a low

cross polarization level.

  A known solution of dual polarization plated antenna, allowing to obtain a wide bandwidth, consists of feeding a radiating element, through two coupling slots cut in a ground plane, by two lines.

  each corresponding to one of the two polarizations.

  This antenna therefore comprises two distinct transmission paths, each

  track being associated with a feed line and a slot.

  Generally, the supply lines are either microstrip type or

of the triplate type.

  In such a known antenna, the radiating element resonates firstly along a first resonance axis perpendicular to the axis of the first slot, and secondly along a second resonance axis perpendicular to the axis of the second slot The intersection of the first and second resonance axes is at an angle

  right and defines a center of resonance.

  This known antenna has many disadvantages, including beam misalignment, cross polarization and coupling between the two channels. Indeed, obtaining a wide bandwidth, using the two resonators that are the slot and the radiating element, requires that they have longitudinal dimensions close Therefore, the slots are large in size, which forces them to shift longitudinally and transversely

  relative to their respective resonance axis.

  Because of the longitudinal shift of each slot, the center of resonance of the slots is not aligned with the center of the radiating element This creates, for the resonator, a phase difference between the two elements constituting this resonator (namely the slot and the radiating element), and thus a misalignment of the beam. In addition, the transverse offset of each slot causes the appearance of

  cross currents which are generating cross polarization.

  Finally, the proximity of the slots to one another, as well as the dissymmetry generated by the various shifts of the slots relative to their respective resonance axis, do not

  not allow to obtain a very large decoupling between the two paths.

  The invention aims in particular to overcome these various drawbacks

from the state of the art.

  More specifically, an object of the invention is to provide a double-polarized plated antenna, of the type comprising at least one radiating element participating in the generation of two microwave waves with distinct polarizations, each radiating element being powered, through at least two slots cut in a ground plane, by two power supplies each corresponding to one of the

  two distinct polarizations, this antenna having a wide bandwidth.

  The invention also aims to provide such an antenna that allows to greatly reduce the coupling and the level of cross polarization, and eliminate the misalignment of the beam, while maintaining a wide bandwidth. These objectives as well as others which will appear subsequently, are achieved according to the invention with the aid of a double-polarized plated antenna, of the type

  comprising at least one radiating element generating two microwave waves

  these with distinct linear polarizations, each of said radiating elements being fed, through at least two slots cut in a ground plane, by a first and a second supply lines each corresponding to one of said distinct polarizations, each of said radiating elements being fed on the one hand by said first feed line through a first slot, and secondly by said second feed line through a second and third slot of the same length (L 2) and parallel to each other, each said resonant radiating elements: on the one hand, along a first resonance axis perpendicular to the axis of said first slot, and on the other hand, along a second resonance axis perpendicular to the axis of each of said second and third slots , the intersection of said first and second resonance axes being at a right angle and defining a center of resonance, said first said slot being on the one hand centered transversely to said first resonance axis and, on the other hand, centered longitudinally with respect to said resonance center,

  and said second and third slots being on the one hand centered transverse

  relative to said second resonance axis and on the other hand placed

  distance from said center of resonance.

  In this way, the slots are not offset transversely This topological arrangement of the coupling slots makes it possible to avoid the appearance of

  cross currents, and thereby the generation of cross polarization.

  In addition, the symmetry of the slots with respect to their respective resonance axis also makes it possible to greatly reduce the coupling between the two channels corresponding to the two polarizations, namely on the one hand the first channel comprising the first power line and the first one. slot, and secondly the second channel comprising the second supply line and the second and third slots Indeed, this symmetry allows to eliminate in pairs the capacitive couplings between the first slot directed along the second resonance axis, and the second and third slots directed along the first axis of

resonance.

  In a preferred embodiment of the invention, the antenna comprises a first and a second radiating element, said second radiating element being disposed in a plane substantially parallel to the plane of said first radiating element, said first and second radiating elements being fed: on the one hand by said first supply line through said first slot, and on the other hand by said second supply line through said second and third slots, said first and second resonant radiators on the one hand according to said first axis of resonance and secondly

  according to said second resonance axis.

  Thus, the radiating elements both contribute to the generation of the two microwave waves with distinct polarizations, and it is possible to reduce the size of the first slot and increase the frequency decoupling between the two channels. Advantageously, said resonance center is located on a straight line perpendicular to the plane or planes containing said radiating element (s).

  and on the other hand passing through the center of said radiating element or elements.

  So, the center of resonance is aligned with the center of each of the two

  radiating elements Consequently, the misalignment of the beam is eliminated.

  Advantageously, the length of said first slot is smaller than

  at the length of said second and third slots.

  Because of this difference in size, the slots do not resemble the same

  frequency and decoupling between the two paths is further improved.

  Preferably, said second and third slots are remote from said first slot. This distance from the slots relative to each other allows

  also to improve the decoupling between the two paths.

  Advantageously, said first and second feed lines belong to the group comprising: microstrip lines;

the lines treble.

  In a preferred embodiment, said slots are of shape

  substantially rectangular and said radiating elements are substantially

square.

  Finally, the invention also relates to a transmission / reception device

  comprising at least one antenna according to the invention.

  This device may comprise several antennas, in particular in the form of

networks.

  Other characteristics of the invention will appear on reading the

  following description of a preferred embodiment of the invention given to

  As an indicative and nonlimiting example, and the appended drawings, in which:

  FIG. 1 shows a view from above of a preferred embodiment of

  of an antenna according to the invention; FIG. 2 shows a sectional view of the antenna shown in FIG.

1;

  Figure 3 shows a logic diagram summarizing the operating principle of an antenna according to the invention as shown in Figures 1 and 2; FIG. 4 shows the curve of variation, as a function of frequency, of the decoupling between the two transmission paths of an antenna such as L presented in FIGS. 1 and 2; FIGS. 5 and 6 each show the variation curve, as a function of frequency, of the standing wave ratio, respectively for the first and the second transmission path of an antenna as shown in FIGS. 1 and 2; Figure 7 shows a co-polarization diagram of one of the two transmission paths of an antenna as shown in Figures 1 and 2; Figure 8 shows a cross-polarization diagram of one of the two transmission paths of an antenna as shown in Figures 1 and 2; FIG. 9 presents a table of correspondence between the references of the curves presented in FIGS. 7 and 8 and the different field levels.

radiated by the antenna.

  The invention therefore relates to a dual polarized plated antenna.

  Figures 1 and 2 respectively show a view from above and a view

  in section of a preferred embodiment of an antenna according to the invention.

  Such an antenna comprises in particular: a first 11 and a second 12 radiating elements; a first 13 and a second 14 supply lines; a first 15, a second 16 and a third 17 slits cut in a second 18 ground plane; a first ground plane 19 and several substrate layers 110

at 115.

  These various elements constituting the antenna are arranged in superimposed planes in the following order, starting from the lower plane: the first ground plane 19; two substrate layers 115, 114; the two feed lines 13, 14; a substrate layer 113; the second ground plane 18 in which are cut the three slots 15, 16, 17; a substrate layer 112; the first radiating element 11; a substrate layer 111; the second radiating element 12;

a substrate layer 110.

  The first supply line 13 cooperates with the first slot 15 The second supply line 14 comprises two arms 14 A '14 B, each arm of this second supply line cooperating with one of the second and third slots (namely the first arm referenced 14 A 'with the second slot 16 and the second arm,

  referenced 14 Bs with the third slot 17).

  The second and third slots 16, 17 are of the same length L 2 and

parallel to each other.

  Each of the two radiating elements 11,12 resonates: firstly along a first resonance axis 116 perpendicular to the axis 117 of the first slot 15; and secondly according to a second resonance axis 118 perpendicular to the axis

  119 of each of the second and third slots 16,17.

  In the embodiment shown in FIG. 1, the second resonance axis 118 is identical to the axis 117 of the first slot 15, and the first axis

  resonance 116 is identical to the axis 119 of the second and third slots.

  The intersection of the first and second resonance axes 116, 118 is

  at a right angle and defines a center of resonance 120.

  According to the invention, the topological arrangement of the slots is as follows: the first slot 15 is centered on the one hand transversely to the first resonance axis 116, and on the other hand centered longitudinally with respect to the resonance center 120; the second and third slots 16, 17 are on the one hand centered transversely with respect to the second resonance axis 118, and

  on the other hand placed equidistant from the resonance center 120.

  So, these second and third slots 16, 17 behave like

  a single slot centered longitudinally and transversely.

  In other words, the first slot 15 is perpendicular to the second and third slots 16, 17, and is placed equidistant from each of the second and third slots 16, 17 The axis 117 of this first slot 15 passes through the center of

  each of the second and third slots 16, 17.

  In this embodiment, the slots are rectangular and the length L1 of the first slot 15 is smaller than the length L 2 of each of the second

and third slots 16, 17.

  The first and second radiating elements 11, 12 have a substantially square shape. For each of these two elements, a center is defined

  geometric (121 and 122 respectively).

  The center 121 of the first radiating element 11, the center 122 of the second radiating element 12 and the resonance center 120 of the slots 15, 16, 17 are aligned on a straight line 123 perpendicular to the planes containing the first and second radii.

  second radiating elements 11, 12.

  The first slot 15 is superimposed with the central zone of each of the first and second radiating elements 11, 12 The second and third slots 16, 17 are superimposed with the peripheral zones of the first and second radiating elements 11, 12, these zones being located from both sides of the central area and

away from it.

  The first and second feed lines 13, 14 are, for example,

  Triplate lines it can also be microstrip lines.

  Figure 3 presents a logic diagram summarizing the principle of

  operation of an antenna according to the invention.

  Such an antenna comprises two transmission channels.

  The antenna emits two waves 31, 32 of the same frequency but of polarization

  each polarization corresponding to one of the two channels of

transmission.

  Generally, the two distinct polarizations are linear polarizations. The first transmission path is represented by line arrows

  full, the second transmission path being represented by dashed arrows.

  The information of the first transmission path is provided by the first power supply line 33 This first power supply line 33 feeds, through the first slot 34, on the one hand the first radiating element 35 and on the other hand the second radiating element 36 These two radiating elements 35, 36 participate in the generation of the first wave 31 having the first

polarization.

  The information of the second transmission path is provided by the second power supply line 37. This second supply line feeds, through the second and third slots 38, 39, on the one hand the first radiating element 35 and on the other. secondly the second radiating element 36 These two radiating elements 35, 36

  participate in the generation of the second wave 32 having the second polarization.

  Thus, by applying this principle of operation to an antenna as presented above in connection with FIGS. 1 and 2, a double polarization plated antenna is obtained (the two polarizations being linear and orthogonal to each other). whose performances are presented in relation to

Figures 4 to 8.

  Figure 4 shows the decoupling variation curve (in d B) between

  the two transmission paths as a function of frequency (in G Hz).

  This decoupling is less than -35 dB over the entire bandwidth 41 of the two transmission paths, ie between 1.4 GHz and 1.7 G (approximately Hz As explained below in connection with FIGS. 5 and 6, the bandwidth of each transmission channel is defined as the set of wave frequencies for

  which the Stationary Wave Ratio (ROS) is less than 2.

  This very large decoupling value is due to the topological arrangement of the coupling slots. Indeed, this symmetrical arrangement makes it possible to eliminate the capacitive coupling between the first slot on the one hand and the capacitive couplings in pairs.

  second and third slots on the other hand.

  FIGS. 5 and 6 each show the curve of variation of the standing wave ratio (ROS) as a function of the frequency, respectively for the

  first and second way of transmission.

  Each of these two curves makes it possible to calculate the bandwidth lf 1, f 2 l of a transmission channel, the bandwidth being equal to the frequency band for which the ROS is less than 2 This bandwidth can also be expressed in percentage, obtained by dividing the width (f 2 f 1) of the band

  passing through the central frequency (f 3) of this bandwidth.

  For the first transmission channel (FIG. 5), the bandwidth 51 is substantially between f 1 = 1.41 GHz and f 2 = 1.71 G Hz with a frequency

  central f 3 = 1.55 GHz, this bandwidth 51 is equal to 19%.

  For the second transmission channel (FIG. 6), the bandwidth 61 is substantially between f 1 = 1.38 GHz and f 2 = 1.70 G Hz with a frequency

  central f 3 = 1.55 GHz, this bandwidth 61 is equal to 21%.

  In summary, the antenna according to the invention has a wide bandwidth

  on each of the two transmission paths.

  FIG. 7 shows the co-polarization diagram of the second transmission path of the antenna shown in FIGS. 1 and 2, for an equal frequency

at 1.43 GHz.

  This co-polarization diagram comprises a plurality of curves represented in a coordinate system whose axes correspond substantially to the axes of

  resonance of the slots (axes referenced 116, 118 in Figure 1).

  Each curve corresponds to a distinct level of field radiated by the antenna. The different possible levels are represented on the table of FIG. 9 which indicates the correspondence between the curve references and the values

  associated with the radiated field level.

  The analysis of this diagram in co-polarization shows that the antenna according to the invention makes it possible to avoid misalignment of the beam for the frequency 1.43 G Hz

  since the maximum radiated field corresponds to the center of resonance.

  In addition, the inventors have also shown that the antenna according to the invention makes it possible to avoid misalignment also for all the others

bandwidth frequencies.

  The elimination of the misalignment of the beam is obtained in particular by aligning the center of each of the two radiating elements with the center of the beam.

resonance of the slits.

  FIG. 8 shows the cross-polarization diagram of the second transmission channel of the antenna shown in FIGS. 1 and 2 for a

frequency equal to 1.43 GHz.

  This cross-polarization diagram comprises, like the co-polarization diagram presented in relation with FIG. 7, a plurality of level curves. The analysis of this diagram shows that the cross polarization of the second transmission path is less than -33 d B for this frequency, in the radio axis of the antenna. The inventors have also shown that the crossed polarization of the first transmission path has the same performance The inventors have also shown that these results are valid

  for all frequencies of the bandwidth.

  This low level of cross polarization is obtained with the antenna according to the invention, in particular thanks to the transverse symmetry of the slots with respect to their

resonance axis.

  The preferred embodiment of an antenna according to the invention,

  shown in relation to Figures 1 to 8, comprises two radiating elements.

  It is clear that the invention is not limited to this case alone but

  also the case where the antenna comprises only one radiating element.

Claims (9)

  A double-polarized plated antenna, of the type comprising at least one radiating element (11, 12) generating two distinct linearly polarized microwave waves, each of said radiating elements (11, 12) being fed through at least two slots (15, 16,17) cut in a ground plane (18), by a first (13) and a second (14) supply line each corresponding to one of said distinct polarizations, characterized in that each of said radiating elements (11,12 ) is fed: on the one hand by said first supply line (13) through a first slot (15), and on the other hand by said second supply line (14) through a second (16) and a third (17) slot of the same length (L 2) and parallel to each other, each of said resonant radiating elements: firstly, according to a first resonance axis (116) perpendicular to the axis (117) of said first slot; (15), and other things rt, along a second resonance axis (118) perpendicular to the axis (119) of each of said second (16) and third (17) slots, the intersection of said first (116) and second (118) resonance axes is making at a right angle and defining a resonance center (120),   in that said first slot (15) is on the one hand centered transverse-   with respect to said first resonance axis (116) and further centered longitudinally with respect to said resonance center (120), and in that said second (16) and third (17) slots are on the one hand transversely centered with respect to said second resonance axis (118) and   on the other hand placed equidistant from said resonance center (120).   Antenna according to claim 1, characterized in that it comprises a first and a second radiating element (12), said second radiating element (12) being arranged in a plane substantially parallel to the plane of said first radiating element (11), and said first (11) and second (12) radiating elements are fed: firstly by said first supply line (13) through said first slot, and secondly by said second supply line ( 14) through said second (16) and third (17) slots, said first (11) and second (12) radiating elements resonating on the one hand along said first resonance axis (116) and on the other hand according to said second axis of resonance (118).   Antenna according to one of Claims 1 and 2, characterized in that   said resonance center (120) is situated on a straight line (123) perpendicular to said plane or planes containing said radiating element or elements (11, 12) and on the other hand passing through the center (121, 122). ) of the said element or elements radiating (11,12).   Antenna according to one of Claims 1 to 3, characterized in that   the length (L1) of said first slot (15) is shorter than the length   (L 2) of said second (16) and third (17) slots.   Antenna according to one of claims 1 to 4, characterized   what said second (16) and third (17) slots are away from said first slot (15).   Antenna according to one of Claims 1 to 5, characterized   said first (13) and second (14) feed lines belong to the group consisting of: microstrip lines; the lines treble.   Antenna according to one of Claims 1 to 6, characterized in that   said shaped slits (15, 16, 17) are of substantially rectangular shape.   Antenna according to one of Claims 1 to 7, characterized in that   the at least one radiating element (11, 12) is substantially square in shape.   9 Transmitting / receiving device comprising at least one antenna according to   any of claims 1 to 8.