Antenna array for reduced sidelobes

Abstract

An antenna array (1) according to the invention comprises at least four antenna columns (2a, 2b, 2c, 2d, 2e), wherein the antenna columns (2a, 2b, 2c, 2d, 2e) are aligned in a plane that is extending in a x-direction and a y-direction, the x-direction being perpendicular to the y-direction Each antenna column (2a, 2b, 2c, 2d, 2e) comprises multiple radiating elements (4a - 4j), wherein the radiating elements (4a - 4j) of each antenna column (2a, 2b, 2c, 2d, 2e) are consecutively aligned in the y-direction between a first end (6) and second end (7) of the respective antenna column (2); wherein the multiple antenna columns comprise a first outermost antenna column (2a), a second outermost antenna column (2e) and at least two inner antenna columns (2b, 2c, 2d), wherein the inner antenna columns (2b, 2c, 2d) are aligned in between the first outermost antenna column (2a) and the second outermost antenna column (2e) in the x-direction; wherein a first shifting distance (8a, 8b, 8c) of each inner antenna column (2b, 2c, 2d), which is a distance in the y-direction between a geometric middle (5b, 5c,5d) in the y-direction of the respective inner antenna column (2b, 2c, 2d) and the geometric middle (5a) in the y-direction of the first outermost antenna column (2a), is larger than zero; and wherein a second shifting distance (9a, 9b, 9c) of each inner antenna column (2b, 2c, 2d), which is a distance in the y-direction between a geometric middle (5b, 5c,5d) in the y-direction of the respective inner antenna column (2b, 2c, 2d) and the geometric middle (5e) in the y-direction of the second outermost antenna column, is larger than zero.

Description

[0001] Antenna array for reduced sidelobes

[0002] Technical field

[0003] The invention refers to an antenna array.

[0004] Massive MIMO Array-Antennas are large panel arrays with a high number of radiators, for example more than 1000 radiators. With this, the equivalent isotropically radiated power (EIRP) will increase more and more and satellite interference must be avoided.

[0005] Satellite interference occurs when an antenna array is transmitting in a direction above the horizon. In this case, the transmitted electromagnetic waves will propagate through the earths atmosphere and will potentially be received by satellites in the orbit. As the number of antenna arrays that are used by communication networks is increasing all over the planet it is important that the electromagnetic waves that are transmitted into the earths orbit is limited, as these electromagnetic waves are disturbing the communication paths of satellites. It is expected that national or international regulations will be put into place for limiting satellite interferences that are caused by antenna arrays.

[0006] Many types of antenna arrays according to the art can be adjusted to have a mainlobe that is adjusted in a way that the direction of the mainlobe is below the horizon to minimize the radiation that is transmitted into space. However, these antennas often have sidelobes that are a side effect of the beamforming that is performed by these antenna arrays. These sidelobes are often directed in a direction above the horizon. Therefore, it can be necessary to reduce the transmission power of the antenna array to avoid satellite interference and to fulfil any potential regulations that have been implemented to limit satellite interferences. However, such a reduction of transmission power is not desirable, as this limits the working range of the antenna array.

[0007] US2022 / 0069461A1 discloses an antenna array according to the art that comprises multiple antenna columns.

[0008] An antenna array according to the invention comprises multiple antenna columns, wherein the multiple antenna columns are at least four antenna columns, wherein the multiple antenna columns are aligned in a plane that is extending in a x-direction and a y-direction, the x-direction being perpendicular to the y-direction; wherein each antenna column comprises multiple radiating elements, wherein the radiating elements of each antenna column are consecutively aligned in the x-direction between a first end and second end of the respective antenna column, wherein all antenna columns are configured to be operated in the same frequency range; wherein the multiple antenna columns comprise a first outermost antenna column, a second outermost antenna column and at least two inner antenna columns, wherein the inner antenna columns are aligned in between the first outermost antenna column and the second outermost antenna column in the x-direction; wherein a first shifting distance of each inner antenna column, which is a distance in the y-direction between a geometric middle in the y-direction of the respective inner antenna column and the geometric middle in the y-direction of the first outermost antenna array, is larger than zero; and wherein a second shifting distance of each inner antenna column, which is a distance in the y-direction between a geometric middle in the y-di- rection of the respective inner antenna array and the geometric middle in the y-direction of the second outermost antenna array, is larger than zero.

[0009] Such antenna array allows a high upper sidelobe suppression and grating-lobe suppression above the horizon. In particular, an equivalent isotropic radiated power (EIRP) of a mainlobe can be maintained high, which allows an effective communication over large distance between the antenna array and a further wireless device. At the same time, an EIRP of sidelobes of the antenna array can be limited, which leads to a reduction of satellite interference. The sidelobe suppression above horizon is much more energy efficient and enables large panel arrays to be used.

[0010] It is further noted that that the described techniques also allow sidelobe suppression for other reasons than avoiding satellite interference. For example, the sidelobe suppression can be used to avoid interferences between the antennas of neighbouring cells of a communications network.

[0011] The antenna array comprises multiple columns, wherein the columns extend in the y-direction. The term “column” is not necessarily indicating that the y-direction is a vertical direction. The multiple antenna columns are at least four antenna columns. Preferably, the multiple antenna columns are at least five antenna columns, more preferably at least six antenna columns.

[0012] Each antenna column comprises multiple radiating elements. Each radiating element is preferably configured to transmit electromagnetic waves with two different, preferably perpendicular, polarizations. The radiating elements of each antenna column are consecutively aligned in the y-direction between a first end and second end of the respective antenna column. That is, the radiating elements of each antenna column to allow beam steering, wherein a tilt angle of the emission direction can be adjusted. The tilt angle is preferably an angle in a plane that is extending in z-direction and y-direction, wherein the z-direction is perpendicular to the x-direction and the y-direction. The first end is an outer edge of a first radiating element of the respective column in y-direction. The second end is an outer edge of a last radiating element of the respective column in y-direction. All other radiating elements of the respective column are aligned in between the first radiating element and the last radiating element on the sides of the inner edges of the first radiating element and the last radiating element.

[0013] The multiple antenna columns comprise a first outermost antenna column, a second outermost antenna column and at least two inner antenna columns, wherein the inner antenna columns are aligned in between the first outermost antenna column and the second outermost antenna column in the x-direction. Therefore, the antenna array comprises multiple essentially parallel columns.

[0014] The first shifting distance of each inner antenna column, which is the distance in the y-direction between a geometric middle in the y-direction of the respective inner antenna column and the geometric middle in the y-direction of the first outermost antenna array, is larger than zero. This means that the first shifting distance of each inner antenna column is defined by the relative position of the respective inner antenna column to the first outermost antenna array. The geometric middle is the middle in between the first end and the second end of each antenna column. The second shifting distance of each inner antenna column, which is the distance in the y-direc- tion between a geometric middle in the y-direction of the respective inner antenna array and the geometric middle in the y-direction of the second outermost antenna array, is larger than zero. This means that the second shifting distance of each inner antenna column is defined by the relative position of the respective inner antenna column to the second outermost antenna array.

[0015] Consequently, the geometric middle of each inner antenna column is shifted in the same direction, that is the y-direction, in respect to the two outermost antenna arrays. All inner antenna columns are shifted in the same direction in respect to the first and / or second outermost antenna column.

[0016] The dependent claims define advantageous aspects of the invention.

[0017] In particular, the multiple antenna columns comprise a central inner antenna column in the y- direction, wherein the central inner antenna column is one of the inner antenna columns with a largest first shifting distance of the inner antenna columns, wherein the first shifting distance for all inner antenna columns between the first outermost antenna column and the central inner antenna column is either increasing or constant for subsequent neighboring inner antenna columns when starting from the first outermost antenna column, and / or wherein the second shifting distance for all inner antenna columns between the second outermost antenna column and the central inner antenna column is either increasing or constant for subsequent neighboring inner antenna columns when starting from the second outermost antenna column. Therefore, the shifting distance for all inner antenna columns between the outermost antenna column and the central inner antenna column is increasing over the range of inner antenna columns starting from the outermost antenna columns until a maximum is reached at the central inner antenna column. The central inner antenna column is not necessarily the middle one of the inner antenna columns, even though this is advantageous. There can be more than one central inner antenna column if there are multiple inner antenna columns with the same largest first shifting distance and / or multiple inner antenna columns with the same largest second shifting distance. In particular, the geometric middles of the antenna columns between the first outermost antenna column and the central inner antenna column are aligned to provide a stepwise increase of the first shifting distance from the first outermost antenna column towards the central inner antenna column, and / or wherein the geometric middles of the antenna columns between the second outermost antenna column and the central inner antenna column are aligned to provide a step- wise increase of the second shifting distance from the second outermost antenna column towards the central inner antenna column. A stepwise increase is an increase in which the difference between the first shifting distance or the second shifting distance is not constantly increasing over adjacent inner antenna columns. In particular, the first shifting distance or the second shifting distance is constant for at least two adjacent inner antenna columns and is then increasing for the following at least two adjacent inner antenna columns, wherein the shifting distance is constant for the following at least two adjacent inner antenna columns.

[0018] In particular, the first shifting distance is increasing in at least two or at least three steps in between the first outermost antenna column and the central inner antenna column. It is advantageous that the second shifting distance is increasing in at least two or at least three steps in between the second outermost antenna column and the central inner antenna column.

[0019] In particular, the first shifting distance is equal to the second shifting distance for each one of the inner antenna columns. This means that the first shifting distance is equal to the second shifting distance for all inner antenna columns. For example, the first shifting distance of a first one of the inner antenna columns is equal to the second shifting distance of the first one of inner antenna columns. The first shifting distance of the first one of the inner antenna columns can be different to the first and second shifting distance of a second one of inner antenna columns. This allows to minimize sidelobes that are tilted in a xz-plane, which is a plane that extends in the x-direction and in the z-direction, wherein the z-direction is perpendicular to the x- direction and to the y-direction. In the alternative, the first shifting distance is different to the second shifting distance for each one of the inner antenna columns. In particular, the multiple antenna columns are aligned such that the antenna columns are symmetrical in respect to a symmetry axis that is extending in y-direction. With this, a symmetric radiation pattern can be achieved.

[0020] In particular, the antenna columns have the same length in y-direction. This allows that multiple ones the same type of antenna columns can be manufactured and can be combined to the antenna array or at least components of the antenna column can be reused for all antenna columns of the antenna array. In the alternative, the antenna columns have a variable length in the y-direction.

[0021] In particular, the antenna columns have the same number of radiating elements. This allows that multiple ones the same type of antenna columns can be manufactured and can be combined to the antenna array. In the alternative, at least two of the antenna columns have a different number of radiating elements.

[0022] In particular, the geometric middles of all antenna columns are forming a u-shape or v-shape. This allows that undesired sidelobes can be further minimized. It is noted that the u-shape or v- shape is still understood as such a shape in case the antenna array is rotated in the xy-plane. The u-shape or v-shape can be upside down, depending on the alignment of the antenna array.

[0023] In particular, the antenna column is segmented into multiple subarrays, each subarray comprising one or more radiating elements of the respective antenna column. In particular, each subarray is configured to independently adjust a direction of the mainlobe. This allows a improved beam-handling, for example as required for Ml MO-antennas.

[0024] In particular, at least two of the subarrays comprise a different number of radiating elements. In particular, at least two of the subarrays of the same antenna column comprise a different number of radiating elements. As different numbers of radiating elements lead to different shapes and directions of the corresponding sidelobes, this allows a further reduction of undesirable sidelobes or to a decrease of the EIRP in a specific direction.

[0025] In particular, the subarrays of one antenna column are segmenting the respective antenna column into asymmetrical portions in respect to the subarrays. This allows to avoid an overlap of sidelobes of different subarrays in any specific direction.

[0026] In particular, each subarray of one column is supplied with the same output power. This allows an implementation of power tapering. In particular, the power tapering can be achieved in combination with subarrays with different numbers of radiating elements. In the alternative, at least two subarrays of one column are supplied with a different output power. This allows an implementation of power tapering. In particular, the power tapering can be achieved in combination with subarrays with the same number of radiating elements.

[0027] In particular, the first shifting distance and / or the second shifting distance is equal to or a multiple of a segmentation distance, wherein the segmentation distance is the length of one of outermost antenna columns in y-direction divided by the number of radiating elements on this outermost antenna column. This allows that rows of radiating elements are formed in the antenna array, which allows an easier implementation of beam steering in the x-direction, optionally multiplied by a integer factor. Preferably, the integer factor is equal to one, two or three.

[0028] In particular, each antenna column is configured to have a mainlobe that is tilted to have an angle of more than zero degree in respect to a z-direction, wherein the z-direction is perpendicular to the x-direction and the y-direction. In particular, if the antenna array is mounted in an elevated position, this allows to direct the mainlobe towards the ground, improving efficiency of the antenna array. At the same time, sidelobes that are not directed towards the ground are minimized.

[0029] In particular, each antenna column is configured such that the mainlobe has the angle of more than zero degree is set as an initial direction, wherein each antenna column further comprises means for beam steering that are configured to adjust a direction of the mainlobe to derive from the initial direction. This allows to further adjust the antennas mainlobe, for example to point towards a UE in the surrounding area of the antenna area.

[0030] In particular, the antenna array is configured to apply power tapering to at least one of the antenna columns. This allows a fine adjustement of the sidelobe suppression and further decreases undesired sidelobes.

[0031] An antenna system comprising an antenna array according to the invention is capable to achieve all advantages of the antenna array. Preferably, the antenna array is mounted in the antenna system such that the x-direction is a horizontal direction and the y-direction is a vertical direction. Thus, it can be avoided that sidelobes of the antenna array are transmitting in a direction above the horizon, therefore avoiding satellite interferences.

[0032] Next phase of Massive Ml MO Array-Antennas are large panel arrays with a high number of radiating elements, for example more than 1000 radiator ports. EIRP will increase more and more and satellite interference must be avoided. To overcome this challenge antenna arrays with high upper sidelobe suppression and grating-lobe suppression above horizon are needed. The invention is suitable to achieve high sidelobe-suppression and grating-lobe suppression above horizon. Existing technology often uses power- backoff to overcome satellite interference. An antenna solution with high or very high sidelobe suppression above horizon will be much more en- ergy efficient and enable large panel arrays to be used.

[0033] Brief description of the drawings

[0034] Fig. 1 shows a single antenna column of an exemplary antenna array according to the invention, fig. 2 shows an exemplary antenna array according to an embodiment of the invention and is indicating the first shifting distances of the inner antenna arrays, fig. 3 shows an exemplary antenna array according to an embodiment of the invention and is indicating the second shifting distances of the inner antenna arrays, fig. 4 shows an antenna array according to an embodiment of the invention, fig. 5 shows an antenna array according to the embodiment of the invention, wherein the antenna columns are segmented into subarrays, fig. 6 shows an exemplary antenna column of an exemplary antenna array according to the invention and a diagram that is indicating a corresponding power distribution, wherein the antenna column is segmented into equal sized subarrays, fig. 7 shows an exemplary antenna column of an exemplary antenna array according to the invention and a diagram that is indicating a corresponding power distribution, wherein the antenna column is asymmetrically segmented into differently sized subarrays, fig.8 shows an antenna array according to the embodiment of the invention, wherein the geometric middles of the antenna arrays are aligned in a first v-shape, fig. 9 shows an antenna array according to the embodiment of the invention, wherein the geometric middles of the antenna arrays are aligned in a second v-shape, fig. 10 shows an antenna according to the invention that comprises an antenna array according to the invention, fig. 11 shows a comparison of an antenna array according to the art with exemplary antenna arrays according to the invention, fig. 12a and 12b show diagrams that are indicating the reduction of an undesired sidelobe that can be achieved for the exemplary antenna arrays according to the invention of figure 11, fig. 13 shows further exemplary antenna arrays according to the invention, and figs 14a and 14b show advantageous orientations of an exemplary antenna array according to the invention.

[0035] Detailed description

[0036] Figure 1 shows a single antenna column 2 of an exemplary antenna array 1 according to aspects of the invention. The antenna column 2 aligned in a xy-plane that is extending in a x-direc- tion and in a y-direction, wherein the x-direction is perpendicular to the y-direction. The antenna column 2 comprises multiple radiating elements 4a - 4j, wherein the radiating elements 4a - 4j of the antenna column 2 are consecutively aligned in the y-direction between a first end 6 and second end 7 of the antenna column 2.

[0037] The depicted exemplary antenna column 2 of figure 1 comprises ten radiating elements 4a - 4j, that is a first radiating element 4a, a second radiating element 4b, a third radiating element 4c, a fourth radiating element 4d, a fifth radiating element 4e, a sixth radiating element 4f, a seventh radiating element 4g, an eighth radiating element 4h, a ninth radiating element 4i and a tenth radiating element 4j. It is noted that the number of radiating elements is only chosen by example. The radiating elements 4a - 4j are radiating elements that are capable to emit radio waves with two different polarizations, wherein one polarization plane is rotated +45 degrees from the y-direction and one polarization plane is rotated -45 degrees from the y-direction. The radiating elements are aligned in one line along the y-direction. All radiating elements 4a - 4j are configured to be operated in the same frequency range.

[0038] The antenna column is foreseen to emit radio signals in a y-direction, wherein the y-direction is perpendicular to the x-direction and the y-direction. However, it is noted that the mainlobe of the antenna column 2 can be tilted away from being parallel to the y-direction. For example, the radiating elements 4a - 4j can be supplied with phase shifted transmission signal, which allows to tilt the mainlobe of the antenna column 2 to tilt within an yz-plane, that is a plane that is extending in the y-direction and the z-direction.

[0039] The antenna column 2 has a geometric middle 5 in the y-direction. The geometric middle is not necessarily a constructive element but is a position in between the outer ends of the antenna column in y-direction. That is. A first distance 6a from the first end 6 to the geometric middle 5 is equal to a second distance 6b between the second end 6 and the geometric middle 5.

[0040] Optionally, the antenna column is segmented into subarrays 3, 3’. A subarray is an association of two or more of the radiating elements 4a - 4j. In one example, each subarray 3,3’ comprises a dedicated control electronic, wherein the radiating elements 4a - 4j of one subarray are controlled by the control electronic of this subarray. For example, the dedicated control electronic is configured to control a tilt angle of the mainlobe of the subarray 3. In another example, the radiating elements 4a - 4j of one subarray are supplied with a transmission signal that is dedicated to this subarray. In another example, the radiating elements 4a - 4j of one subarray are supplied via a dedicated amplifier that is dedicated to this subarray.

[0041] The exemplary antenna column 2 of figure 1 is segmented into a first subarray 3 and a second subarray 3’. The first subarray 3 comprises the first to fifth radiating element 4a - 4e. The second subarray 3’ comprises the sixth to tenth radiating element 4f - 4j. The subarrays 3, 3’ are indicated by a square in dashed lines that includes the radiating elements of one subarray.

[0042] Figure 2 shows an exemplary antenna array 1 according to aspects of the invention and is indicating first shifting distances of inner antenna arrays. The antenna array 1 comprises multiple antenna columns 2a, 2b, 2c, 2d, 2e. Each one of the antenna columns 2a, 2b, 2c, 2d, 2e is an antenna column as described in view of figure 2. Therefore, each antenna column 2a, 2b, 2c, 2d, 2e comprises multiple radiating elements 4a - 4j, wherein the radiating elements 4a - 4j of each antenna column 2a, 2b, 2c, 2d, 2e are consecutively aligned in the y-direction between the first end 6 and the second end 7 of the respective antenna column 2. The antenna columns 2a, 2b, 2c, 2d, 2e are arranged parallel to each other, wherein the antenna columns are extending in the y-direction. The multiple antenna columns 2a, 2b, 2c, 2d, 2e are at least four antenna columns 2, in the depicted example five antenna columns, wherein the multiple antenna columns 2a, 2b, 2c, 2d, 2e are aligned in the xy-plane that is extending in the x-direction and the y-direc- tion.

[0043] As each one of the antenna columns 2a, 2b, 2c, 2d, 2e is an antenna column as described in view of figure 2, all antenna columns 2a, 2b, 2c, 2d, 2e are configured to be operated in the same frequency range.

[0044] The multiple antenna columns 2a, 2b, 2c, 2d, 2e comprise a first outermost antenna column 2a, a second outermost antenna column 2e and at least two inner antenna columns 2b, 2c, 2d. A set of inner antenna columns 2b, 2c, 2d is aligned in between the first outermost antenna column 2a and the second outermost antenna column 2e in the x-direction. In the given example, all of the multiple antenna columns 2a, 2b, 2c, 2d, 2e that are located in between the first and the last antenna column 2a, 2c are referred to as the inner antenna columns 2b, 2c, 2d. According to the example that is depicted in figure 2, there are three inner antenna columns 2b, 2c, 2d. However, according to aspects of the invention there might be only two inner antenna columns or there might be more than three inner antenna columns in between the outermost antenna columns 2a, 2e. In this example, the first outermost antenna column 2a is the first antenna column in the x-direction and the second outermost antenna column 2e is the last antenna column in the x-direction. In the alternative, the first outermost antenna column 2a is the last antenna column in the x-direction and the second outermost antenna column 2e is the first antenna column in the x-direction. The antenna array 1 of figure 2 comprises the inner antenna columns 2b, 2c, 2d, which are a first inner antenna column 2b, a second inner column 2c and a third inner column 2d.

[0045] A first shifting distance 8a, 8b, 8c is defined for each one of the inner antenna columns 2b, 2c, 2d. The first shifting distance is a distance in the y-direction between the geometric middle 5b, 5c, 5d of the respective inner antenna column 2b, 2c, 2d and the geometric middle 5a of the first outermost antenna column 2a. The first shifting distance is larger than zero for all inner antenna columns 2b, 2c, 2d.

[0046] For example, the first shifting distance 8a of the first inner antenna column 2b is the distance between the geometric middle 5a of the first outermost antenna column 2a and the geometric middle 5b of the first inner antenna column 2b in y-direction. Accordingly, the first shifting distance 8b of the second inner antenna column 2c is the distance between the geometric middle 5a of the first outermost antenna column 2a and the geometric middle 5b of the second inner antenna column 2c in y-direction. Accordingly, the first shifting distance 8c of the third inner antenna column 2d is the distance between the geometric middle 5a of the first outermost antenna column 2a and the geometric middle 5c of the third inner antenna column 2d in y-direction.

[0047] As the first shifting distances 8a, 8b, 8c of the inner antenna columns 2b, 2c, 2d are all larger than zero, the geometric middles 5b, 5c, 5d of the inner antenna columns 2b, 2c, 2d are all shifted in respect to the geometric middle 5a of the first outermost antenna column 2a. In figure 2, this shift is a downward shift, as the y-direction is from top to bottom in figure 2. However, the shift can also be an upward shift, as it can also be understood that the y-direction is from bottom to top.

[0048] A second shifting distance 8a, 8b, 8c is defined for each one of the inner antenna columns 2b, 2c, 2d, which is illustrated by figure 3. The second shifting distance is a distance in the y-direc- tion between the geometric middle 5b, 5c, 5d of the respective inner antenna column 2b, 2c, 2d and the geometric middle 5e of the second outermost antenna column 2e. The second shifting distance is larger than zero for all inner antenna columns 2b, 2c, 2d.

[0049] For example, the second shifting distance 9a of the first inner antenna column 2b is the distance between the geometric middle 5e of the second outermost antenna column 2e and the geometric middle 5b of the first inner antenna column 2b in y-direction. Accordingly, the second shifting distance 9b of the second inner antenna column 2c is the distance between the geometric middle 5e of the second outermost antenna column 2e and the geometric middle 5b of the second inner antenna column 2c in y-direction. Accordingly, the second shifting distance 9c of the third inner antenna column 2d is the distance between the geometric middle 5e of the second outermost antenna column 2e and the geometric middle 5c of the third inner antenna column 2d in y- direction.

[0050] The first shifting distances 8a, 8b, 8c and the second shifting distances 9a, 9b, 9c are equal to a segmentation distance 10, wherein the segmentation distance is the length of one of outermost antenna columns 2a, 2e in y-direction divided by the number of radiating elements 4e - 4j on this outermost antenna column 2a, 2e. In other words, the first inner antenna column 2b is shifted by the length of one radiating element 4 in respect to the first outermost antenna column 2a and the second inner antenna column 2c is shifted by the length of one radiating element 4 in respect to the first inner antenna column 2b. The third inner antenna column 2c is shifted by the length of one radiating element 4 in respect to the second outermost antenna column 2e and the second inner antenna column 2b is shifted by the length of one radiating element 4 in respect to the third inner antenna column 2c. Setting the first shifting distances 8a, 8b, 8c and the second shifting distances 9a, 9b, 9c to be equal to the segmentation distance 10 is optional.

[0051] As the second shifting distances 9a, 9b, 9c of the inner antenna columns 2b, 2c, 2d are all larger than zero, the geometric middles 5b, 5c, 5d of the inner antenna columns 2b, 2c, 2d are all shifted in respect to the geometric middle 5e of the second outermost antenna column 2e in the same direction the shifted in respect to the geometric middle 5a of the first outermost antenna column 2a. In figure 3, the shift is a downward shift, as the y-direction is from top to bottom in figure 3. However, the shift can also be an upward shift, as it can also be understood that the y-direction is from bottom to top.

[0052] Figure 4 shows the antenna array 1 of figures 2 and 3 without the indication of the shifting distances 8a, 8b, 8c, 9a, 9b, 9c, wherein further advantageous features are described in the following. The first shifting distance 8a, 8b, 8c is equal to the second shifting distance 9a, 9b, 9c for all inner antenna columns 2b, 2c, 2d. The antenna columns 2a, 2b, 2c, 2d, 2e are all of the same constructive type and therefore have the same length in y-direction and are aligned such that the antenna array 1 is symmetrical in respect to a symmetry axis 11 that is extending in y-direc- tion. Thus, the multiple antenna columns 2a, 2b, 2c, 2d, 2e are aligned such that the antenna columns 2a, 2b, 2c, 2d, 2e are symmetrical in respect to the symmetry axis 11. The antenna columns 2a, 2b, 2c, 2d, 2e have the same number of radiating elements 4, which are depicted as diagonal crosses in the figures, wherein all antenna columns 2a, 2b, 2c, 2d, 2e have the same exemplary number of ten radiating elements 4.

[0053] The multiple antenna columns 2a, 2b, 2c, 2d, 2e comprise a central inner antenna column in the y-direction, wherein the central inner antenna column is one of the inner antenna columns 2b, 2c, 2d with a largest first shifting distance. In the example of figures 2 to 4, the second inner antenna column 2c is the central inner antenna column, as the first shifting distance 8b of the second inner antenna column 2c is larger than the first shifting distance 8a of the first inner antenna column 2b and larger than the first shifting distance 8c of the third inner antenna column 2d.

[0054] The first shifting distance for all inner antenna columns 2a, 2b, 2c between the first outermost antenna column 2a and the central inner antenna column, that is the second inner antenna column 2c, is increasing for subsequent neighboring inner antenna columns 2a, 2b, 2c when starting from the first outermost antenna column 2a. However, it is noted that the first shifting distance can be equal for some of the inner antenna columns 2a, 2b, 2c, for example as illustrated with figure 7. In this case, two or more neighboring ones of the inner antenna columns 2a, 2b, 2c have the same first shifting distance.

[0055] The second shifting distance for all inner antenna columns 2a, 2b, 2c between the second outermost antenna column 2e and the central inner antenna column, that is the second inner antenna column 2c, is increasing for subsequent neighboring inner antenna columns 2a, 2b, 2c when starting from the second outermost antenna column 2e. However, it is noted that the second shifting distance can be equal for some of the inner antenna columns 2a, 2b, 2c, for example as illustrated with figure 7. In this case, two or more neighboring ones of the inner antenna columns 2a, 2b, 2c have the same second shifting distance.

[0056] The geometric middles 5a, 5b, 5c, 5d, 5e of all antenna columns 2a, 2b, 2c, 2d, 2e are forming a v-shape 12. The geometric middles of figure 4 are on a curve that is approximated to the position of the geometric middles, which means that the geometric middles 5a, 5b, 5c, 5d, 5e of all antenna columns 2a, 2b, 2c, 2d, 2e are forming a v-shape 12. In particular, the v-shape is achieved when the first shifting distance and the second shifting distance is constantly increasing towards the central inner antenna column, this leads to an arrangement of the geometric middles 5a - 5d that can be seen as a v-shape. In case that the second shifting distance is increasing in smaller steps towards the central inner antenna column, this can be seen as a u- shape.

[0057] Figure 5 shows the antenna array of figure 4, wherein each one of the antenna columns 2a, 2b, 2c, 2d, 2e is segmented into multiple subarrays. Each subarray comprises one or more radiating elements 5a - 5j of the respective antenna column 2a, 2b, 2c, 2d, 2e. A subarray is a set of radiating elements that are combined to work as subarray.

[0058] In the example of figure 5, each one of the multiple antenna columns 2a, 2b, 2c, 2d, 2e comprises two subarrays 3, 3', the two subarrays being a first subarray 3 and second subarray 3’. The first subarray 3 of the first outermost antenna column 2a comprises six radiating elements, that is the first radiating element 4a, the second radiating element 4b, the third radiating element 4c, the fourth radiating element 4d, the fifth radiating element 4 e and the sixth radiating element 4f. The second subarray 3' of the first outermost antenna column 2a comprises four radiating elements, that is the seventh radiating element 4g, the eighth radiating element 4h, the ninth radiating element 4i and the tenth radiating element 4j. As the first subarray 3 comprises six radiating elements and the second subarray 3’ comprises four radiating elements, there are at least two of the subarrays of one antenna column that comprise a different number of radiating elements 5a - 5j. The further antenna columns 2b, 2c, 2d, 2e are segmented the same way, which is advantageous. However, it is noted that different segmentations can be applied to different antenna columns. It is noted that subarrays of different antenna columns are optionally combined to form a single subarray.

[0059] The subarrays 3, 3’ of one antenna column 2a, 2b, 2c, 2d, 2e are segmenting the respective antenna column into asymmetrical portions in respect to the subarrays 3, 3’. Referring to the first outermost antenna column 2a, it can be seen that the subarrays cannot be split into two symmetric portions in the y-direction, as the subarrays 3, 3’ have a different size and there are only two subarrays. To achieve a symmetric arrangement of subarrays, it would be necessary that the same structure of subarrays is provided above and below the geometric middle of an antenna column. To achieve an asymmetric arrangement of subarrays, a different structure of subarrays is provided above and below the geometric middle of an antenna column.

[0060] Figure 6 shows an antenna column that is segmented into subarrays, wherein the subarrays all have the same number of radiating elements. Figure 7 shows an antenna column that is segmented into subarrays, wherein the subarrays have a variable number of radiating elements. The antenna column according to figure 6 and the antenna column according to figure 7 can be used in an antenna column according to aspects of the invention. In the following, the technique of power tapering based on the segmentation of subarrays with different sizes is described by referring to figures 6 and 7.

[0061] Figure 6 shows an antenna column 2 that is segmented into subarrays 3, wherein the subarrays all have the same number of radiating elements 4. In the depicted example, the antenna column 2 is segmented into eight subarrays 3, wherein each subarray 3 comprises 4 radiating elements 4. Each subarray 3 is supplied with an input signal that is supplied to a phase shifter port 21 - 28 of the corresponding subarray 2 and is from there distributed to the radiating elements 4 of the corresponding subarray 3. The input signal has a specific power amplitude, wherein the power amplitude is the same for all subarrays 2. That is, the same power amplitude is provided to all of phase shifter ports 21 - 28 of the subarrays 3 of the antenna column 2. The power amplitude of the input signal that is provided to the phase shifter ports 21 - 28 is illustrated in the upper diagram of figure 6. The diagram is indicating the power amplitude for the phase shifter ports 21 - 28 of the eight subarrays 3, wherein the phase shifter ports 21 - 28 that are in a down-to-up order in figure 6 are presented from left to right in the upper diagram of figure 5. As the same power amplitude is provided to all subarrays and therefore to all phase shifter ports 21 - 28, the same power amplitude is indicated for the phase shifter ports 21 - 28.

[0062] The lower diagram in figure 6 is illustrating the power amplitude that is provided to each radiating element. The diagram is indicating the power amplitude for the radiating elements of the eight subarrays 3, wherein the radiating elements 4 that are aligned consecutively in a down-to- up order in figure 6 are presented from left to right in the lower diagram of figure 6. As the same power amplitude is provided to all subarrays and this input power amplitude is split into the same number of radiating elements 4 for each subarray, the same power amplitude is indicated for each radiating element 4.

[0063] Figure 7 shows an antenna column 2 that is segmented into subarrays 3, wherein the subarrays all have a variable number of radiating elements 4. In the depicted example, the antenna column 2 is segmented into eight subarrays 3, wherein the number of radiating elements is split into a 5:4:3:3:2:4:5:5 segmentation when starting from the bottom subarray in figure 7. Each subarray 3 is supplied with an input signal that is supplied to a phase shifter port 21 - 28 of the corresponding subarray 2 and is from there distributed to the radiating elements 4 of the corresponding subarray 3. The input signal has a specific power amplitude, wherein the power amplitude is the same for all subarrays 2. That is, the same power amplitude is provided to all of phase shifter ports 21 - 28 of the subarrays 3 of the antenna column 2. The power amplitude of the input signal that is provided to the phase shifter ports 21 - 28 is illustrated in the upper diagram of figure 6. The diagram is indicating the power amplitude for the phase shifter ports 21 - 28 of the eight subarrays 3, wherein the phase shifter ports 21 - 28 that are in a down-to-up order in figure 7 are presented from left to right in the upper diagram of figure 5. As the same power amplitude is provided to all subarrays and therefore to all phase shifter ports 21 - 28, the same power amplitude is indicated for the phase shifter ports 21 - 28.

[0064] The lower diagram in figure 7 is illustrating the power amplitude that is provided to each radiating element. The diagram is indicating the power amplitude for the radiating elements of the eight subarrays 3, wherein the radiating elements 4 that are aligned consecutively in a down-to- up order in figure 7 are presented from left to right in the lower diagram of figure 7. As the same power amplitude is provided to all subarrays and this input power amplitude is split into different numbers of radiating elements 4 for the subarrays 3, the radiating elements are supplied with different power amplitudes, depending on the number of radiating elements 4 in their subarray 3. For example, it can be seen that the subarray with the fifth phase shifter port 25 has only two radiating elements. Therefore, the provided power amplitude is split up by two radiating elements, leading to a higher power amplitude per radiating element 4 than for an antenna array with six radiating elements 4, for example the subarray with the first phase shifter port 21.

[0065] It can be seen that the power amplitude that is applied to individual radiating elements can be shaped by choosing the segmentation of the antenna column 2 into subarrays 3. The shaping of the curve that power amplitude over the radiating elements to minimize undesired sidelobes of the antenna array 1 is referred to as power tapering.

[0066] Figures 8 and 9 are illustrating exemplary antenna arrays 1 , wherein the techniques that have been described with figures 1 to 8 are applied. It can be seen that the techniques according to aspects of the invention can be applied to antenna arrays with high numbers of radiating elements, for example to an antenna array 1 with a total number of 512 radiating elements 4. The exemplary arrays comprise a first outermost antenna column 2a, a second outermost antenna column 2e and a central inner antenna column 2c. However, the number of inner antenna columns between the first outermost antenna column 2a and the central inner antenna column 2c, as well as the number of inner antenna columns between the second outermost antenna column 2e and the central inner antenna column 2c has increased. It is noted that there are two antenna columns with a largest first shifting distance, which means that there are two central inner antenna columns. More specifically referring to Figure 8, it can be seen that the geometric middles 5 of all antenna columns 2 are forming a v-shape 12. The geometric middles 5 of all antenna columns 2 is located in between the sixteenth and the seventeenth radiating element 4 of each antenna column 2 when counting from any side of the antenna column 2. The first shifting distance for all inner antenna columns 2 between the first outermost antenna column 2a and the central inner antenna column 2c is either increasing or constant for subsequent neighboring inner antenna columns 2a, 2b, 2c when starting from the first outermost antenna column 2a. Referring to figure 8, it can be seen that the first shifting distance is always increasing for the subsequent neighboring inner antenna columns 2 between the first outermost antenna column 2a and the central inner antenna column 2c. Also, it can be seen that the second shifting distance for all inner antenna columns 2 between the second outermost antenna column 2e and the central inner antenna column 2c is always increasing for subsequent neighboring inner antenna columns 2 when starting from the second outermost antenna column 2e.

[0067] Further referring to figure 9, it can be seen that the first shifting distance and / or the second shifting distance can be equal for some of the adjacent inner antenna columns. Further than that, it can be seen that there is more than one first outermost antenna column 2a and more than one second outermost antenna column 2e. That is, it can be understood that additional first outermost antenna columns 2a’ can be optionally added on an outer side of the first outermost antenna column 2a, the outer side being opposite to the inner antenna columns. Also, it can be understood that additional second outermost antenna columns 2e’ can be optionally added on an outer side of the second outermost antenna column 2e, the outer side being opposite to the inner antenna columns. Any additional outermost antenna column preferably has a first shifting distance of zero.

[0068] Figure 10 shows an antenna 30 that comprises the antenna array 1 according to aspects of the invention. The antenna 30 is mounted such that the antenna array 1 is aligned vertical. That is, the y-direction is a vertical direction. The antenna 30 is an antenna of a mobile communications network and is mounted on a pole 31 above the ground 32. A direction of a mainlobe 35 is tilted towards the horizontal z-direction by a first angle a. This tilt by the first angle a is achieved by applying a phase shift between the radiating elements of each antenna column 2 of the antenna array 1. Due to the tilt, the antenna 30 as the mainlobe directed towards the ground and therefore towards a likely position of a user equipment 33 of the mobile communications network. The first angle a can be adapted to increase or decrease in respect to an initially set angle, for example to adapt the mainlobe to point towards the UE 33.

[0069] In particular, each antenna column 2 is configured to have a mainlobe that is tilted to have the first angle a of more than zero degree in respect to the z-direction, wherein the z-direction is perpendicular to the x-direction and the y-direction. Further than that, each antenna column is preferably configured such that the direction of the mainlobe with the first angle a of more than zero degree is set as an initial direction, wherein each antenna column 2 further comprises means for beam steering that are configured to adjust a direction of the mainlobe to derive from the initial direction.

[0070] Even though the mainlobe is directed towards a desired direction, it is a side effect that a sidelobe of the antenna array 1 is directed towards a sidelobe direction 36, wherein the sidelobe direction 36 is tilted upwards by a second angle towards the direction of a mainlobe 35 in the zy-plane. This can lead to the effect that radio waves are transmitted into a direction that is pointing above the horizon and potentially towards a satellite 34 in orbit. Therefore, the sidelobe can lead to interferences in a communication of the satellite 34, which is known as satellite interference. The invention allows to reduce the sidelobe of the antenna 30 that can lead to satellite interference.

[0071] Figure 11 is showing three different antenna arrays. That is, figure 11 shows a conventional antenna array 40, a first antenna array 41 and a second antenna array 42. The conventional antenna array 40 is not according to the invention. The inner antenna arrays of the conventional antenna array 40 all have a shifting distance of zero. The first antenna array 41 is an antenna array according to aspects of the invention, wherein each antenna column 2 is segmented into two antenna arrays 3, 3’ of the same size. No power tapering is implemented to the first antenna array 41 . The inner antenna columns of the first antenna array 41 all have a first and second shifting distance larger than zero, wherein the first and second shifting distance is increasing by the segmentation distance 10 with each antenna column 2, wherein the segmentation distance 10 is double the length of one of outermost antenna columns 2a, 2e in y-direction divided by the number of radiating elements 4e - 4j on this outermost antenna column 2a, 2e, multiplied by the value two. The second antenna array 42 essentially corresponds to the first antenna array 41 but the segmentation of each antenna column 1 into the subarrays 3, 3’ has been chosen differently, such that each antenna column 2 is segmented asymmetrically into the two antenna subarrays 3, 3’. One antenna subarray 3 of the second antenna array 42 comprises six radiating elements 4 and the other antenna array 3’ of the second antenna array 42 comprises ten radiating elements 4. Power tapering is implemented by the antenna arrays 3, 3’ of the second antenna array 42. The conventional antenna array 40, the first antenna array 41 and the second antenna array 42 are by example configured to have a tilting angle of 2°, previously referred to as first angle a. Figure 12a is a first diagram that is illustrating a directivity of the conventional antenna array 40 of figure 11 in a first curve 50 and a directivity of the first antenna array 41 of figure 11 in a second curve 51. The diagram is illustrating an antenna gain in d Bi dependent on an angle over the y-direction in the yz-plane from 0° to 180°, covering all directions over the antenna arrays. It can be seen that a highest peak of the antenna gain is at 92° for the conventional antenna array 40 and the first antenna array 41. This is the mainlobe of these antenna arrays 40, 41. The value is 92°, as the direction of the mainlobe has been described as the first angle a in respect to the z- direction while first diagram is referring to an angle in respect to the y-direction. Thus, the mainlobe that occurs at the tilt angle of 2° leads to the peak at 92° in the first diagram.

[0072] The neighboring peaks are caused by sidelobes, wherein in particular the sidelobes that occur in the range between 0° and 90° can lead to satellite interference, as these sidelobes are in a direction that is pointing above the horizon when the y-direction is the vertical direction. It can be seen that the antenna gain is significantly lower for the sidelobes of the first antenna array 41 that is indicated by the second curve 51 when compared to the sidelobes of the conventional antenna array 40 that is indicated by the first curve 50. By example, this is illustrating one of the advantageous effects that is achieved by the selection of the shifting distances according to aspects of the invention. It is further noted that the same effect is achieved for the sidelobes above 2°.

[0073] Figure 12b is a second diagram that is illustrating the directivity of the first antenna array 41 of figure 11 in the first curve 51 , as also indicated in the first diagram, and a directivity of the second antenna array 42 of figure 11 in a third curve 52. Same as the first diagram, the second diagram is illustrating an antenna gain in dBi dependent on an angle over the y-direction in the yz- plane from 0° to 180°, covering all directions over the antenna arrays. It can be seen that a highest peak of the antenna gain is at 92° for the first antenna array 41 and the second antenna array 42. This is the mainlobe of these antenna arrays 41 , 42. The value is 92°, as the direction of the mainlobe has been described as the first angle a in respect to the z-direction while first diagram is referring to an angle in respect to the y-direction. Thus, the mainlobe that occurs at the tilt angle of 2° leads to the peak at 92° in the first diagram.

[0074] It can be seen that the sidelobes in the range between 0° and 90° are further reduced. Thus, it can be seen that the additional power tapering that has been implemented by the asymmetric segmentation of each antenna column 2 into subarrays leads to a further decrease of sidelobes.

[0075] Exemplary antenna arrays according to aspects of the invention are large panel array with a frequency operating range from 5,9 to 8,4 GHz or 10,7 to15,35 GHz. The antenna arrays are con- figured to perform full digital beamforming with 256 TRx. In an example with 1024 radiating elements, the antenna array comprises 32 radiators vertically x 16 columns x 2 polarization, wherein a combination of two radiators with for two polarizations is referred to as radiating element. The different number of subarray-radiating elements can be used for vertical power-tapering and column-sidelobe suppression. The subarrays are preferably configured with downtilt.

[0076] According to aspects of the invention, a sidelobe- and grating-lobe suppression can be improved by approximately 10 to 20dB.

[0077] Figure 13 is showing three different antenna arrays according to the invention. That is, figure 13 shows a third antenna array 43, a fourth antenna array 44 and a fifth antenna array 45.

[0078] The third antenna array 43 corresponds to the first antenna array 41 , wherein the geometric middle of the two outermost antenna columns 2a, 2e that are shifted in respect to each other in the y-direction. This leads to the fact that the first shifting distance is different to the second shifting distance for each one of the inner antenna columns.

[0079] The fourth antenna array 44 corresponds to the first antenna array 41 , wherein the antenna columns 2 have a variable length in the y-direction. For example, the first inner antenna column 2b comprises more radiating elements 4 than the first outermost antenna column 2a, wherein the interval of radiating elements 4 in y-direction is equal for all radiating elements 4. Therefore, the first inner antenna column 2b is longer than the first outermost antenna column 2 and the antenna columns 2 have a variable length in the y-direction. With this, two of the antenna columns have a different number of radiating elements 4. In the alternative, the length of an antenna column can be adjusted by changing the distance between the radiating elements 4 in an antenna column 2.

[0080] The fifth antenna array 45 corresponds to the first antenna array 41 , wherein at least two of the antenna columns have a different number of radiating elements 4. At the same time, the length of the antenna columns is not changed, as the distance between the radiating elements 4 of the antenna column with less radiating elements 4 is larger than the distance between the radiating elements 4 of the antenna column 2 with more radiating elements 4.

[0081] Figures 14a and 14b show advantageous orientations of an exemplary antenna array 1 according to the invention. For this, Figures 14a and 14b are showing different orientations of the antenna array in relation to the ground 32. Figure 14a shows an alignment in which the y-direction is a up-down direction. Figure 14b shows an alignment in which the y-direction is a down-up direction. Both alignments are advantageous, as sidelobes that are pointing in a direction above the horizon are minimized. It is noted that the antenna arrays 1 that are shown in Figures 14a and 14b correspond to the described first antenna array 41. However, the alignment is advantageous for all antenna arrays 1 according to the invention.

Claims

Claims1. Antenna array (1), wherein the antenna array (1) comprises multiple antenna columns (2a, 2b, 2c, 2d, 2e), wherein the multiple antenna columns (2a, 2b, 2c, 2d, 2e) are at least four antenna columns (2), wherein the multiple antenna columns (2a, 2b, 2c, 2d, 2e) are aligned in a plane that is extending in a x-direction and a y-direction, the x-direction being perpendicular to the y-di- rection; wherein each antenna column (2a, 2b, 2c, 2d, 2e) comprises multiple radiating elements (4a - 4j), wherein the radiating elements (4a - 4j) of each antenna column (2a, 2b, 2c, 2d, 2e) are consecutively aligned in the y-direction between a first end (6) and second end (7) of the respective antenna column (2), wherein all antenna columns (2a, 2b, 2c, 2d, 2e) are configured to be operated in the same frequency range; wherein the multiple antenna columns comprise a first outermost antenna column (2a), a second outermost antenna column (2e) and at least two inner antenna columns (2b, 2c, 2d), wherein the inner antenna columns (2b, 2c, 2d) are aligned in between the first outermost antenna column (2a) and the second outermost antenna column (2e) in the x-direction; wherein a first shifting distance (8a, 8b, 8c) of each inner antenna column (2b, 2c, 2d), which is a distance in the y-direction between a geometric middle (5b, 5c, 5d) in the y-direction of the respective inner antenna column (2b, 2c, 2d) and the geometric middle (5a) in the y- direction of the first outermost antenna column (2a), is larger than zero; and wherein a second shifting distance (9a, 9b, 9c) of each inner antenna column (2b, 2c, 2d), which is a distance in the y-direction between a geometric middle (5b, 5c, 5d) in the y-di- rection of the respective inner antenna columns (2b, 2c, 2d) and the geometric middle (5e) in the y-direction of the second outermost antenna column (2e), is larger than zero.

2. Antenna array (1) according to claim 1 , wherein the multiple antenna columns comprise a central inner antenna column (2c) in the y-direction, wherein the central inner antenna column (2c) is one of the inner antenna columns (2b, 2c, 2d) with a largest first shifting distance (8b) of the inner antenna columns (2b, 2c, 2d), wherein the first shifting distance (8b) for all inner antenna columns (2a, 2b, 2c) between the first outermost antenna column (2a) and the central inner antenna column (2c) is either increasing or constant for subsequent neighboring inner antenna columns (2a, 2b, 2c) when starting from the first outermost antenna column (2a), and / or wherein the second shifting distance (8b) for all inner antenna columns (2a, 2b, 2c) between the second outermost antenna column (2e) and the central inner antenna column (2c) is either increasing or constant for subsequent neighboring inner antenna columns (2a, 2b, 2c) when starting from the second outermost antenna column (2e).

3. Antenna array (1) according to any one of the preceding claims, wherein the geometric middles (5a, 5b, 5c) of the antenna columns (2a, 2b, 2c, 2d, 2e) between the first outermost antenna column (2a) and the central inner antenna column (2c) are aligned to provide a stepwise increase of the first shifting distance (8b) from the first outermost antenna column (2a) towards the central inner antenna column (2c), and / or wherein the geometric middles (5c, 5d, 5e) of the antenna columns (2a, 2b, 2c, 2d, 2e) between the second outermost antenna column (2e) and the central inner antenna column (2c) are aligned to provide a stepwise increase of the second shifting distance (8b) from the second outermost antenna column (2e) towards the central inner antenna column (2c).

4. Antenna array (1) according to any one of the preceding claims, wherein the first shifting distance (8a, 8b, 8c) is equal to the second shifting distance (9a, 9b, 9c) for each one of the inner antenna columns (2b, 2c, 2d).

5. Antenna array (1) according to any one of the preceding claims, wherein the multiple antenna columns (2a, 2b, 2c, 2d, 2e) are aligned such that the antenna columns (2a, 2b, 2c, 2d, 2e) are symmetrical in respect to a symmetry axis (11) that is extending in y-direction.

6. Antenna array (1) according to any one of the preceding claims, wherein the antenna columns (2a, 2b, 2c, 2d, 2e) have the same length in y-direction.

7. Antenna array (1) according to any one of the preceding claims, wherein the antenna columns (2a, 2b, 2c, 2d, 2e) have the same number of radiating elements (4a - 4j).

8. Antenna array (1) according to any one of the preceding claims, wherein the geometric middles (5a, 5b, 5c, 5d, 5e) of all antenna columns (2a, 2b, 2c, 2d, 2e) are forming a u-shape or v-shape.

9. Antenna array (1) according to any one of the preceding claims, wherein each antenna column (2a, 2b, 2c, 2d, 2e) is segmented into multiple subarrays, each subarray comprising one or more radiating elements (5a - 5j) of the respective antenna column (2a, 2b, 2c, 2d, 2e).

10. Antenna array (1) according to claim 9, wherein at least two of the subarrays comprise a different number of radiating elements (5a - 5j).

11. Antenna array (1) according to claim 10, wherein the subarrays of one antenna column (2a, 2b, 2c, 2d, 2e) are segmenting the respective antenna column into asymmetrical portions in respect to the subarrays.

12. Antenna array (1) according to any one of the preceding claims 9 to 11 , wherein each subarray of one column is supplied with the same output power.

13. Antenna array (1) according to any one of the preceding claims, wherein the first shifting distance (8a, 8b, 8c) and / or the second shifting distance (9a, 9b, 9c) is equal to or a multiple of a segmentation distance (10), wherein the segmentation distance (10) is the length of one of outermost antenna columns (2a, 2e) in y-direction divided by the number of radiating elements (4e - 4j) on this outermost antenna column (2a, 2e), optionally multiplied by a integer factor.

14. Antenna array (1) according to any one of the preceding claims, wherein each antenna column is configured to have a mainlobe that is tilted to have an angle of more than zero degree in respect to a z-direction, wherein the z-direction is perpendicular to the x-direction and the y- direction.

15. Antenna array (1) according to claim 14, wherein each antenna column is configured such that the mainlobe has the angle of more than zero degree is set as an initial direction, wherein each antenna column further comprises means for beam steering that are configured to adjust a direction of the mainlobe to derive from the initial direction.

16. Antenna array (1) according to any one of the preceding claims, wherein the antenna array (1) is configured to apply power tapering to at least one of the antenna columns (2a, 2b, 2c, 2d, 2e).

17. Antenna system, the antenna system comprising an antenna array (1) according to any one of the preceding claims.

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