ES2939371T3 - antenna system - Google Patents

Abstract

The invention refers to a "low profile" antenna system (10) comprising a source (12) capable of emitting at least one beam, the source (12) comprising at least one linear set of antennas, each linear set being capable of emitting a beam, and a reflector (14) having the shape of a parabolic trough, the reflector (14) being arranged to reflect at least one beam. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

antenna system

[0001] The present invention relates to an antenna system.

[0002] WO 2009/025458 A1, US 2471284 A, US 3267472 A, JP S61 157105 A, the article "Beam Squint Compensation in Circularly Polarized Offset Reflector Antennas Using a Sequentially Rotated Focal Plane Array" by Zamanifekri et al ., the thesis entitled "Ka-band integrated focal-plane arrays for two-way satellite communication" by Zamanifekri, JP 2000082919 A, US 2011/156948 A1, the article "Focal plan array with Ka-band Silicon transmitter on chip for VSAT application" by Zamanifekri et al., US 2014/326903 A1 and US 2011/063179 A1 disclose antenna systems.

[0003] For satellite communications, it is desirable to integrate antenna systems called "low-profile" into terrestrial or airborne platforms (which literally translates as "low profile" in Spanish).

[0004] By "low-profile" is meant antenna systems with heights less than 20 cm.

[0005] In this communication context, the use of a parabolic-type passive antenna system is known.

[0006] For example, a classical parabola with a symmetrical structure can be used. By "symmetrical structure" is meant a structure that exhibits a symmetry of revolution. This allows to obtain optimal performance in terms of gain and diagram.

[0007] On the contrary, due to the symmetrical structure, the height reached does not make it possible to meet the "low-profile" need.

[0008] According to another example, a satellite dish of the multihome type is used, which makes it possible to reach a height that meets the "low-profile" need.

[0009] However, control of the diagram in the height plane is difficult. The pattern presented by the antenna in this plane is the pattern of a parabola having a small diameter. Such a pattern does not conform to the standardization constraints relating to the radiation pattern.

[0010] It is also known as a flat horn net, also known by the English term "horn box" which literally means "box of horns". With this network, the radiation diagram is easily controllable with the help of a power law chosen for the network and the number of associated horn(s) allows to guarantee the "low-profile" voltage in the desired plane.

[0011] On the contrary, in the plane in which it is not sought to be low profile, if the increase in the number of radiating elements beyond 30 or 40 allows the aperture to be reduced, it will not be possible to increase the gain. In fact, such a lattice is only interesting for dimensions of the planar lattice that have a length less than 40 times the wavelength.

[0012] There is, therefore, a need for an antenna system with a reduced size in height ("lowprofile") with good performance in terms of gain and pattern.

[0013] For this purpose, the invention proposes an antenna system according to claim 1.

[0014] According to particular modes, the antenna system comprises one or more of the characteristics of claims 2 to 7, taken in isolation or according to all technically possible combinations.

[0015] Other features and advantages of the invention will become apparent upon reading the given description of embodiments of the invention, given by way of example only and with reference to the drawings which are:

- Figure 1, a schematic representation in perspective of a first example of an antenna system that does not form part of the invention;

figure 2, a view from above of the antenna system of figure 1;

- figure 3, a view from above of a second example of antenna system that does not form part of the invention; - Figure 4, a view from above of a third example of an antenna system that does not form part of the invention, and - Figure 5, a view from above of a fourth example of an antenna system.

[0016] Figure 1 illustrates a first embodiment of an antenna system 10 that is not part of the invention.

[0017] The antenna system 10 is suitable for receiving and transmitting data in the context of communication, in particular by satellite.

[0018] The antenna system 10 is intended to be installed, for example, on ground or airborne platforms.

[0019] The antenna system 10 comprises a source 12, a reflector 14 and an arm 16.

[0020] In the illustrated example, the source 12 comprises a transmission-reception surface 18 and antennas 20.

[0021] The transmission-reception surface 18 is flat.

[0022] The transmission-reception surface 18 is suitable for receiving the antennas 20.

[0023] More precisely, in the example of FIG. 1, the transmission-reception surface 18 has a rectangular shape having a length and a width.

[0024] A longitudinal direction corresponding to the length of the rectangular shape is defined. The longitudinal direction is symbolized by an X axis in Figure 1.

[0025] A first transverse direction corresponding to the width of the rectangular shape is also defined. The first transverse direction is symbolized by a Y axis in Figure 1.

[0026] A second transverse direction is also defined as perpendicular to the longitudinal direction X and to the first transverse direction Y. The second transverse direction is symbolized by a Z axis in Figure 1.

[0027] In the example of figure 1, the antennas 20 are arranged along two parallel lines L1 and L2.

[0028] According to the example of figure 1, the lines L1 and L2 are according to the longitudinal direction X.

[0029] According to one embodiment, the antennas 20 have a rectangular-type shape.

[0030] Each line L1 and L2 comprises four antennas 20 according to the example of figure 1.

[0031] As a variant, the number of antennas 20 of each L1 or L2 line is, for example, a multiple of two, such as eight or sixteen respecting the "low-profile" character.

[0032] The antennas 20 of each line L1 or L2 are connected to each other so as to form a linear array of antennas 22.

[0033] The antennas 20 of the first line L1 form a first linear array of antennas 22A while the antennas 20 of the first line L2 form a second linear array of antennas 22B.

[0034] Each linear network 22A and 22B is oriented along the longitudinal direction X.

[0035] Each linear array of antennas 22A and 22B is suitable for emitting a beam belonging to a first frequency band and for receiving a beam belonging to a second frequency band, the second frequency band being different from the first band. of frequency.

[0036] The frequency bands are selected from the group consisting of the Ka, Ku and X bands.

[0037] For telecommunications by satellite link, the Ka band corresponds in emission to frequencies between 29 GHz and 31 GHz and, in reception, to frequencies between 19.2 GHz and 21.2 GHz.

[0038] The Ku band corresponds to the part of the electromagnetic spectrum defined by the frequency band from 10 GHz to 15 GHz for satellite communications.

[0039] The X band corresponds to the part of the electromagnetic spectrum defined by a frequency band located around 8 GHz also for satellite communications.

[0040] To this end, each array of antennas 22A and 22B comprises a plurality of elementary antennas and antenna processing electronics.

[0041] The elementary antennas are sized for the band(s) in which the antenna array 22A and 22B is suitable for transmitting or receiving.

[0042] According to a particular example, to facilitate the manufacture of the antenna arrays 20A and 20B, the elementary antennas are all identical.

[0043] The linear arrays of antennas 22A and 22B give the source 12 the property of being dual-band in that the source 12 makes it possible to ensure the transmission and reception functions.

[0044] By way of example, source 12 is suitable for operation in the Ka/Ku band.

[0045] According to a variant, the source 12 is suitable for operation in the Ka/X band.

[0046] The reflector 14 is arranged to reflect each of the beams emitted by the two linear arrays of antennas 22A and 22B.

[0047] The reflector 14 has the shape of a parabolic cylinder.

[0048] By definition, a parabolic cylinder is a portion of a cylinder whose basic shape is a portion of a parabola.

[0049] Otherwise, this means that there is a direction according to which the intersection, when it exists, of any plane, each plane being perpendicular to the direction, with the parabolic cylinder is a parabola.

[0050] A parabola is a plane curve in which each of the points is located at the same distance from a fixed point, called the focus, and from a fixed line, called the directrix.

[0051] The shape of the reflector 14 allows to define two faces, a concave face and a convex face. The face adapted to reflect each of the beams emitted by the two linear arrays of antennas 22A and 22B is the concave face.

[0052] The shape of the reflector 14 allows to define a focal length for the reflector 14.

[0053] The focal length of the reflector 14 is between 10 centimeters and 20 centimeters.

[0054] According to the illustrated example, the focal length of the reflector 14 is equal to 15 centimeters.

[0055] Next, the direction according to which the intersection of any plane perpendicular to the direction with the parabolic cylinder is a parabola is called the first direction D1.

[0056] A median plane P is defined for the reflector 14.

[0057] By definition, the median plane P is the plane containing the first direction D1 and the direction of the reflector 14.

[0058] The direction perpendicular to the median plane P is called the second direction D2.

[0059] The reflector 14 is delimited by four planes, two planes according to the first direction D1 and two planes according to the second direction D2.

[0060] The reflector 14 thus extends along the first direction D1 between a lower side 24 and an upper side 26.

[0061] The reflector 14 also extends in the second direction D2 between a first end 28 and a second end 30.

[0062] By construction, any point located in the median plane P is located equidistant from the two extremes 28 and 30.

[0063] By construction, any plane perpendicular to the median plane P is a plane whose intersection, when it exists, with the reflector 14 is a parabola.

[0064] According to the example of figure 1, the angle between the first direction D1 and the longitudinal direction X is less than or equal to 10° depending on the orientation of the antennas 20.

[0065] In the particular case of figure 1, the first direction D1 is parallel to the longitudinal direction X.

[0066] This means, in particular, that the first direction D1 and the longitudinal direction X are parallel while the second direction D2 and the second longitudinal direction Z are parallel.

[0067] Furthermore, according to the example of Fig. 1, each linear array of antennas 22A and 22B is symmetrical to each other with respect to the median plane P.

[0068] In the example shown, each linear array of antennas 22A, 22B is equidistant from the two ends 28 and 30 of the reflector l4.

[0069] The reflector 14 is made, for example, of a reflective material that can be aluminum, carbon or metallized plastic that makes it possible to reduce its mass.

[0070] As seen in figure 1, the reflector 14 has a first dimension H according to the first direction D1.

[0071] The first dimension H corresponds to the distance measured according to the first direction D1 between the lower side 24 and the upper side 26.

[0072] The first dimension H is between 10 centimeters and 20 centimeters.

[0073] According to the illustrated example, the first dimension H is equal to 15 centimeters.

[0074] The first dimension H is equal to the length of the emission-reception surface 18.

[0075] As can be seen in figure 2, the reflector 14 has a second dimension E along the second direction D2.

[0076] The second dimension H corresponds to the distance measured according to the second direction D2 between the two ends 28 and 30.

[0077] The second dimension E is between 30 centimeters and 50 centimeters.

[0078] According to the illustrated example, the second dimension E is equal to 40 centimeters.

[0079] Arm 16 connects source 12 to reflector 14.

[0080] The connecting element 16 is in the form of a bar that extends along the first transverse direction Y.

[0081] Arm 16 is connected to reflector 14 by a pivot joint connected to underside 24 of reflector 14.

[0082] The arm 16 is articulated about the longitudinal direction X.

[0083] The arm 16 has a length such that the distance between the reflector 14 and the source 12 is between 10 centimeters and 30 centimeters.

[0084] According to the illustrated example, the distance between the source 12 and the reflector 14 measured along the first transverse direction Y is equal to 20 centimeters.

[0085] The arm 16 is, for example, made of a material identical to the material that forms the emission-reception surface 18.

[0086] The operation of the antenna system 10 according to the example of FIG. 1 is now described in transmission and reception.

[0087] In emission, the source 12 emits a beam belonging to a first frequency band towards the reflector 14.

[0088] The beam is then reflected by the reflector 14.

[0089] In reception, a beam belonging to a second incident frequency band arrives at the reflector 14.

[0090] The reflector 14 reflects the beam towards the source 12 from which the antennas 20 receive the beam.

[0091] The transmit and receive operations are implemented, for example, simultaneously.

[0092] Therefore, the proposed antenna system 10 makes it possible to benefit from dual-band operation.

[0093] The antenna system 10 is compact in particular since the first dimension H is less than 30 centimeters.

[0094] Furthermore, the antenna system 10 has a good performance in terms of radiation and pattern.

[0095] Likewise, the control of the radiation pattern according to the longitudinal direction X is facilitated due to the small dimension of the antenna system 10.

[0096] In addition, the antenna system 10 according to the invention makes it possible to easily integrate bipolar operation into the design of the linear arrays of antennas 22A and 22B.

[0097] The antenna system 10 also has a great coverage capacity in terms of the band of operation.

[0098] On the other hand, the antenna system 10 has a low manufacturing cost. In fact, an architecture comprising linear arrays of antennas 22A and 22B that integrate transmission and reception duplexing while being associated with a reflector 14 of particular shape is easily achievable.

[0099] Likewise, the antenna system 10 presents an architecture adapted to multiple uses.

[0100] Other embodiments of the antenna system 10 are presented below.

[0101] A second embodiment that does not form part of the invention is illustrated in Figure 3.

[0102] In what follows, the elements identical to the first embodiment presented in figures 1 and 2 are not described again. Only the differences are highlighted.

[0103] The reflector 14 of the second embodiment differs from the reflector of the first embodiment in that the reflector 14 of Figure 3 comprises a primary reflector 32 and a secondary reflector 34.

[0104] The notes and definitions relating to the reflector 14 of Figure 1 apply also to the reflector 14 of Figure 3, neglecting the presence of the secondary reflector 34.

[0105] In fact, by way of example, the median plane P is defined for the reflector 14 of figure 3 with respect to the primary reflector 32.

[0106] The secondary reflector 34 has an identical shape to the primary reflector 36.

[0107] The secondary reflector 34 has reduced dimensions with respect to the dimensions of the primary reflector 32.

[0108] By way of illustration, the secondary reflector 34 has a second dimension of the same order as the height of the antennas 20 and a first dimension equal to a maximum of 15% of that of the parabolic reflector in order to minimize blockages of the radiation.

[0109] Primary reflector 32 and secondary reflector 34 are positioned in a Cassegrain configuration.

[0110] The primary reflector 32 and the secondary reflector 34 are positioned such that their generators are all parallel to each other and such that their respective concave faces C, C are located opposite. More specifically, the directions of the primary reflector 32 and the secondary reflector 34 are confused.

[0111] For example, the primary reflector 32 and the secondary reflector 34 are located between 15 centimeters and 25 centimeters apart.

[0112] The source 12 is located between the primary reflector 32 and the secondary reflector 34, for example at a distance of less than 10 centimeters from the primary reflector 32.

[0113] The operation of the antenna system 10 according to the example of figure 3 is now described in emission and reception.

[0114] In emission, the source 12 emits a beam belonging to a first frequency band towards the secondary reflector 34.

[0115] The beam is then reflected towards the primary reflector 32 which then reflects the incident beam.

[0116] In reception, a beam belonging to a second incident frequency band arrives at the primary reflector 32.

[0117] The primary reflector 32 reflects the beam towards the secondary reflector 34 which reflects the beam towards the source 12 from which the antennas 20 receive the beam.

[0118] The same advantages as for the first embodiment apply equally to the second embodiment.

[0119] Figure 4 illustrates a third embodiment of the antenna system 10 that does not form part of the invention.

[0120] In what follows, the elements identical to the first embodiment presented in figures 1 and 2 are not described again. Only the differences are highlighted.

[0121] The source 12 differs from the source of the first embodiment in that the source 12 has two sources 40A and 40B conforming to the source 12 of the first embodiment.

[0122] Furthermore, each source 40A, 40B is positioned in front of a respective end 28, 30 of the reflector 14 such that at least one linear array of antennas 22A and 22B is positioned in front of an end 28 and 30.

[0123] The remarks regarding the operation and advantages of the first embodiment apply to the third embodiment as well.

[0124] Figure 5 illustrates a fourth embodiment of the antenna structure.

[0125] In what follows, the elements identical to the third embodiment presented in figure 4 are not described again. Only the differences are highlighted.

[0126] In the case of figure 5, the reflector 14 comprises a primary reflector 32 and two secondary reflectors 34A and 34B suitable for reflecting the beam towards the primary reflector 32, each of the primary reflectors 32 and secondary 34A and 34B having the shape of a parabolic cylinder.

[0127] Analogous notes apply to the second embodiment for the reflector 14 of Figure 5. These comments are not repeated.

[0128] In the case of Fig. 5, each secondary reflector 34A and 34B is symmetrical with respect to the median plane P and each secondary reflector 34A and 34B is located opposite a respective end 28 and 30 of the primary reflector 32.

[0129] The remarks regarding the operation and advantages of the second embodiment also apply to the fourth embodiment.

[0130] In all the embodiments presented, the antenna structure 10 comprises a source 12 suitable for emitting at least one beam, the source 12 comprising at least one linear array of antennas 22A and 22B 20B, each linear array being 22A and 22B suitable for emitting a beam, the antenna structure 10 comprising a reflector 14 having the shape of a parabolic cylinder, the reflector 14 being arranged to reflect at least one beam.

[0131] Such a configuration makes it possible to have an antenna system 10 that has a reduced size in height with good performance in terms of gain and pattern.

[0132] There are other possible embodiments.

[0133] In particular, in some cases, the source 12 comprises more than two transmission-reception surfaces 18 and a greater number of linear arrays of antennas.

Claims (7)

1. Antenna system (10), comprising: - a source (12) suitable for emitting at least one beam, the source (12) comprising at least one linear array of antennas (22A, 22B), each linear array (22A, 22B) being suitable for emitting a beam, and - a reflector (14) arranged to reflect at least the beam, characterized in that the reflector (14) includes a primary reflector (32) and two secondary reflectors (34, 34A, 34B) suitable for reflecting the beam towards the primary reflector (32), each of the primary (32) and secondary reflectors having (34, 34A, 34B) the shape of a parabolic cylinder, a median plane (P) being defined for the reflector (14), each secondary reflector (34A, 34B) being symmetrical with respect to the median plane (P), two ends (28, 30) are defined for the primary reflector (32) , each secondary reflector (34A, 34B) being located opposite a respective end (28, 30) of the primary reflector (32). Antenna system according to claim 1, in which a first direction (D1) is defined for the reflector (14), each linear array of antennas (22A, 22B) being oriented according to a longitudinal direction (X) and the angle between the first direction (D1) and the longitudinal direction (X) less than or equal to 15°. Antenna system according to claim 1 or 2, in which a first direction (D1) is defined for the reflector (14), each linear array of antennas (22A, 22B) being oriented along a longitudinal direction (X) and the angle between the first direction (D1) and the longitudinal direction (X) being less than or equal to 5°. An antenna system according to any one of claims 1 to 3, wherein each linear array of antennas (20A, 20B) is mutually symmetrical with respect to the median plane. Antenna system (10) according to any of claims 1 to 4, in which each linear array of antennas (22A, 22B) is suitable for emitting a beam belonging to a first frequency band and for receiving a beam belonging to a first frequency band. it belongs to a second frequency band, the second frequency band being different from the first frequency band. 6. Antenna system (10) according to claim 5, wherein the frequency bands are operating bands for satellite communication applications and are selected from the group consisting of the Ka, Ku and X bands. Antenna system according to any of claims 1 to 6, in which each linear array of antennas (22A, 22B) is positioned opposite one end (28, 30) or at equidistant from both ends (28, 30).