WO2023093985A1

WO2023093985A1 - An antenna device with two stacked radiating elements

Info

Publication number: WO2023093985A1
Application number: PCT/EP2021/082908
Authority: WO
Inventors: Zhi GONG; Bruno BISCONTINI; Ignacio Gonzalez; Huachun SHEN; Grzegorz WOLOSINSKI; Juan Segador Alvarez
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2023-06-01

Abstract

This disclosure relates to an antenna device, for example, for use in a base station. The antenna device includes two radiating elements arranged on a common axis, for example, arranged or stacked above each other. Each radiating element is configured to radiate a radio wave in response to a RF signal fed to the respective radiating element. The antenna device comprises a feed structure configured to feed the RF signal to the two radiating elements. The feed structure comprises a redirecting device for redirecting the power between two or more branches, and configured to distribute the power of the RF signal between the two radiating elements. The feed structure also comprises a phase inverter configured to set a quasi-inverted phase between the RF signals at the two radiating elements as a first phase difference.

Description

AN ANTENNA DEVICE WITH TWO STACKED RADIATING ELEMENTS

TECHNICAL FIELD

The present disclosure relates to an antenna device, for example, for use in a base station. The antenna device may be referred to as a multi-layered antenna device, as it includes two radiating elements arranged on a common axis, for example, arranged or stacked above each other. The antenna device is designed to have a high radiation directivity. The present disclosure relates also to a method for operating the antenna device.

BACKGROUND

With the Long-Term Evolution (LTE) rollout almost complete, operators are preparing their mobile networks for the upcoming 5^th generation (5G). A key technology for enabling this new generation of mobile communications is massive multiple input multiple output (mMIMO) below 6 GHz. Therefore, new antenna devices are needed that integrate mMIMO with passive antenna arrays.

Several restrictions exist, however, regarding the deployment of new antenna devices. For instance, regulations in many countries, especially in Europe, are a real limiting factor when rolling out new services and infrastructures, and are likely going to be developed slower than new antenna technology. Thus, to facilitate antenna site acquisition, and to fulfil the local regulations regarding antenna site upgrades, the dimensions of any new antenna device should be comparable to those of legacy antenna devices.

In addition, to be able to maintain the mechanical support structures, which are already present at most antenna sites, a wind load of any new antenna device should be comparable or equivalent to the currently installed ones. These factors lead to very strict limitations regarding the width of any new antenna device.

However, the width of an antenna device also influences its radiation directivity. In particular, the radiation directivity of the antenna device is limited by its aperture, and therefore, by its width. This effect becomes particularly critical, when several antenna arrays are placed inside the same enclosure of the antenna device. It is well know that when multiple dipoles are placed in a side by side configuration on a small reflector of an antenna device, the horizontal beam width (HBW) of the antenna device increases, which reduces the radiation directivity.

Some exemplary approaches, which address this reduction of the radiation directivity, attempt to conform the HBW using a 90° hybrid. This hybrid provides a small increment in radiation directivity, but does not exploit fully the reduction of the HBW, because it generates side lobes out of the main cuts. Some other exemplary approaches attempting to address the reduction of the radiation directivity result in antenna devices with an increased depth (or thickness), or a reduced gain, or a reduced bandwidth.

In another approach, one or more end-fire arrays are arranged in the normal direction perpendicular to a reflector, in order to form an improved radiation directivity antenna device. However, also this approach could still be improved, as there are some disadvantages with the implementation of the antenna device, which has a two-layered radiation element: firstly, a long electrical length feeding network leads to resonances, which limit the operating bandwidth of the antenna device; secondly, a 180° phase difference is introduced through a rotating balun feeding structure of an upper and a lower radiating element, which leads to rather large size, high costs, and a difficult production of the baluns; thirdly, the approach is based on a large radiator size.

SUMMARY

In view of the above, a goal of this disclosure is to provide an antenna device that may have a width that complies with regulations and is usable for existing support structures at antenna sites. An objective is, in particular, to ensure that the radiation directivity of the antenna device is high and not significantly reduced compared to a conventional antenna device with a larger width. Consequently, the HBW of the antenna device shall not be significantly widened.

These and other objectives are achieved by the subject matter of the independent claims. Advantageous implementations are further defined in the dependent claims.

A first aspect of this disclosure provides an antenna device comprising: a first radiating element and a second radiating element being arranged on a common axis, each radiating element being configured to radiate a radio wave in response to a radiofrequency (RF) signal fed to the respective radiating element; and a feed structure configured to feed the RF signal to the first radiating element and the second radiating element; wherein the feed structure comprises a redirecting device for redirecting the power between two or more branches, the redirecting device being configured to distribute the power of the RF signal between the first radiating element and the second radiating element; and wherein the feed structure comprises a phase inverter configured to set a quasi-inverted phase between the RF signal at the first radiating element and the RF signal at the second radiating element as a first phase difference.

By setting the first phase difference between the two radiating elements, a combined radiation pattern can be achieved, which is more directive than the radio wave of a simple/single radiating element.

The result may be a significant increase in the directivity of the combined radiation pattern of the antenna device. This allows either a miniaturization of a reflector or an increase in coverage and/or an increased signal to interference plus noise ratio (SINR) provided by the antenna device. The first phase difference, and potentially an amplitude difference as a further degree of freedom, between the RF signals at the two radiating elements, may also be used to improve the front to back and cross-polar discrimination of the antenna device.

The antenna device may have a width that complies with the existing regulations and is usable for existing support structures at antenna sites. This is due to two radiating elements arranged on the common axis, for example, arranged or stacked above each other.

In addition, a long electrical length feeding network is not required for the antenna device, so that the operating bandwidth of the antenna device is not severely limited. The first phase difference may be introduced without a rotating balun feeding structure, which enables a smaller size, lower costs, and less production complexity.

Overall, the antenna device of the first aspect has the advantage that a simple feeding of the two radiating elements is provided, while a high radiation directivity is achieved. Further, the antenna device is suitable for wideband, easy to process, and can be of low cost.

Notably, the antenna device of the first aspect is described as a transmission (not reception) device. However, it can also be operated as a reception device. In an implementation form of the first aspect, the redirecting device is further configured to set a second phase difference, in addition to the first phase difference set by the phase inverter, between the RF signal at the first radiating element and the RF signal at the second radiating element.

The second phase difference can be used to balance the voltage standing wave ration (VSWR) bandwidth and the directivity of the antenna device. For instance, the radiating fields of the two radiating elements (i.e., the radio waves radiated by the radiating elements) can be made to constructively interfere.

In an implementation form of the first aspect, the redirecting device comprises a first way for providing the RF signal to the first radiating element and a second way for providing the RF signal to the second radiating element, wherein the second phase difference is set by the first way having a different lengths than the second way.

This provides a simple way to realize the second phase difference.

In an implementation form of the first aspect the redirecting device of the feed structure comprises: a balun connected to the first radiating element and the second radiating element; and a feeding line for feeding the RF signal to the balun, the feeding line being connected to the balun in a single feeding point.

With the redirecting device realized by a single point feeding and a balun, the feeding of the two radiating elements can be simplified.

In an implementation form of the first aspect, the redirecting device of the feed structure comprises: a balun connected to the first radiating element and the second radiating element; and a feeding line for feeding the RF signal to the balun, the feeding line having a first feeding part and a second feeding part, and the first feeding part being connected to the balun in a different feeding point than the second feeding part.

This provides a different but efficient implementation of the redirecting device. In an implementation form of the first aspect, the balun comprises two conductive parts separated by a gap, the gap intersecting with the feeding line in one or more feeding points.

Thus, the feeding line may be connected by coupled feeding to the balun.

In an implementation form of the first aspect, each feeding point is arranged either between the first radiating element and the second radiating element, or between a reflector of the antenna device and the two radiating elements, or from the top of the first radiating element.

In an implementation form of the first aspect, the balun is connected to the feeding line in one or more feeding points by either coupled feeding or direct feeding.

In an implementation form of the first aspect, the phase inverter comprises a cross-jumpstructure, the cross-jump- structure being designed such that a positive pole of the feed structure cross-jumps to a side of a negative pole of the feed structure, and the negative pole of the feed structure cross-jumps to a side of the positive pole of the feed structure.

With the phase inverter realized by the cross-jump structure, the feeding of the two radiating elements can be simplified.

In an implementation form of the first aspect, the phase inverter is arranged either on one of the first radiating element and the second radiating element, or on a balun of the feed structure connected to the first radiating element and the second radiating element.

In an implementation form of the first aspect, the antenna device further comprises a reflector arranged on the common axis and configured to reflect the radio waves from the first radiating element and the second radiating element into a main radiating direction.

In an implementation form of the first aspect, the first radiating element and the second radiating element are arranged in different planes.

In an implementation form of the first aspect, the different planes are parallel to each other. In an implementation form of the first aspect, the first radiating element and the second radiating element are arranged concentrically on the common axis.

In an implementation form of the first aspect, the feed structure is configured to feed the RF signal in parallel to the first radiating element and the second radiating element.

In an implementation form of the first aspect, at least one of the first radiating element and the second radiating element is a dual-polarized radiating element.

That is, each radiating element may radiate with a first polarization and a second polarization.

In an implementation form of the first aspect, one of the first radiating element and the second radiating element is arranged closer to a reflector of the antenna device than the other radiating element and has a larger radiating area than the other radiating element.

Thus, a shadowing of the lower radiating element by the upper radiating element is reduced.

In an implementation form of the first aspect, the antenna device further comprises a support structure configured to hold the first radiating element and the second radiating element such that both radiating elements are arranged on the common axis.

In an implementation form of the first aspect, the feed structure is at least partly provided on the support structure.

A second aspect of this disclosure provides a method of operating an antenna device comprising a first radiating element and a second radiating element being arranged on a common axis, each radiating element being configured to radiate a radio wave in response to a RF signal fed to the respective radiating element, wherein the method comprises: feeding the RF signal to the first radiating element and the second radiating element; wherein the power of the RF signal is divided between the first radiating element and the second radiating element; and wherein a phase difference of 180° ± a is set between the RF signal at the first radiating element and the RF signal at the second radiating element, wherein a > 0°. The method of the second aspect may operate the antenna device of any implementation form of the first aspect. The method of the second aspect achieves the same advantages as described for the antenna device of the first aspect.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows a basic principle of an antenna device according to an embodiment of this disclosure in (a), and an implementation of the device in (b).

FIG. 2 shows different implementations of an antenna device according to an embodiment of this disclosure, in particular, different examples of the phase inverter.

FIG. 3 shows different implementations of an antenna device according to an embodiment of this disclosure, in particular, different examples of the redirecting device.

FIG. 4 shows various exemplary implementations of an antenna device according to an embodiment of this disclosure.

FIG. 5 shows an antenna device according to an embodiment of this disclosure in a perspective view.

FIG. 6 shows an antenna device according to an embodiment of this disclosure in a topview. FIG. 7 shows further exemplary implementations of an antenna device according to an embodiment of this disclosure.

FIG. 8 shows a method according to an embodiment of this disclosure for operating an antenna device of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1(a) shows an antenna device 100 according to an embodiment of this disclosure. The antenna device 100 may be suitable for a base station of a mobile communication network. In particular, the antenna device 100 may be suitable for a base station antenna drive system.

The antenna device 100 comprises a first radiating element 101 and a second radiating element 102, which are arranged on a common axis 103. Thereby, the first radiating element 101 and the second radiating element 102 may be arranged concentrically on the common axis 103. For instance, the two radiating elements 101 and 102 may be arranged or stacked one above the other along the common axis 103. For example, as shown in FIG. 1, the first radiating element 101 may be arranged above the second radiating element 102. The first radiating element 101 and the second radiating element 102 may be arranged in different planes or layers of the antenna device 100. These different planes or layers may be parallel to each other. Accordingly, the antenna device 100 may be referred to as a multi-layered antenna device.

Each of the radiating elements 101, 102 is configured to radiate a radio wave in response to a RF signal, which is fed to the respective radiating element 101 or 102. Each radiating element 101, 102 may be a dipole. Further, each radiating element 101, 102 may be configured to radiate with a first polarization and with a second polarization, wherein the two polarizations may be orthogonal. To this end, each radiating element 101, 102 may have two different dipole arms.

The antenna device 100 also comprises a feed structure 104, which is configured to feed the RF signal to the first radiating element 101 and the second radiating element 102. For instance, the feed structure may be configured to feed the RF signal in parallel to the first radiating element 101 and the second radiating element 102. The feed structure 104 may comprise multiple components. The feed structure thereby comprises a redirecting device 104 for redirecting power between two or more branches, wherein the redirecting device 104 is configured in the antenna device 100 to distribute the power of the RF signal between the first radiating element 101 and the second radiating element 102. The redirecting device 104 may be a power divider. The feed structure also comprises a phase inverter 105, which is configured to set a quasiinverted phase between the RF signal at the first radiating element 101 and the RF signal at the second radiating element 102 as a first phase difference. The phase inverter 105 may be a phase shifter. The first phase difference may be ±180°.

FIG. 1(b) shows an antenna device 100 according to an embodiment of this disclosure, which builds on the embodiment of the antenna device 100 shown in FIG. 1(a). Same elements in FIG. 1(a) and 1(b) are labelled with the same reference signs, and are implemented likewise.

The antenna device 100 of FIG. 1(b) accordingly also comprises the two radiating elements 101, 102, the redirecting device 104, and the phase inverter 105. In the antenna device 100 of FIG. 1(b), the redirecting device 104 is further configured to set a second phase difference 106, in addition to the first phase difference set by the phase inverter 105, between the RF signal at the first radiating element 101 and the RF signal at the second radiating element 102. To this end, the redirecting device 105 may, for example, comprise a first way or first arm for providing the RF signal to the first radiating element 101, and a second way or second arm for providing the RF signal to the second radiating element 102. In this case, the second phase difference 106 may be set by the first way or first arm having a different lengths than the second way or second arm.

Notably, considering the FIGs. 1(a) and 1(b), the power of the RF signal is divided between the first radiating element 101 and the second radiating element 102. For instance, it may be divided equally between the two radiating elements 101, 102, but it can also be divided unequally between them. In any case, a phase difference of 180° ± a may be set between the RF signal at the first radiating element 101 (e.g., having an absolute phase of O - 180°, wherein <I> is a determined phase value) and the RF signal at the second radiating element 102 (e.g., having an absolute phase of + a). For the antenna device 100 of FIG. 1(a) a = 0°, whereas for the antenna device 100 of FIG. 1(b) a > 0°.

In summary of FIG. 1(a) and 1(b), a basic principle of the antenna device 100 with the duallayer radiating elements 101, 102 is that the redirecting device 104 connects the first (e.g., upper) and second (e.g., lower) radiating elements 101, 102. One of the two radiating elements 101, 102 gets a fixed phase inversion as a first phase difference (shown in FIG. 1(a) and 1(b)). In addition, the two radiating elements 101, 102 may have a second phase difference 106 of a (shown in FIG. 1(b)).

The fixed phase inversion, e.g. a 180° phase shift, may be implemented through a cross-jump structure as the phase inverter 105. The cross-jump structure may be designed such that a positive pole of the feed structure cross-jumps to a side of a negative pole of the feed structure, and the negative pole of the feed structure cross-jumps to a side of the positive pole of the feed structure.

FIG. 2 shows different implementations of an antenna device 100 according to an embodiment of this disclosure, which build on the embodiments shown in FIG. 1(a) and 1(b). Same elements in these figures are labelled with the same reference signs, and are implemented likewise.

In particular, FIG. 2 shows different examples of the phase inverter 105, especially how the phase inverter 105 - for example, implemented as cross-jump structure - can be introduced at different locations of the feed structure. For instance, the phase inverter 105 may be arranged on the first radiating element 101 (see FIG. 2(a)), or on the second radiating element 102 (see FIG. 2(c)). Alternatively, the phase inverter 105 may be arranged on a balun 201 of the feed structure of the antenna device 100 (see Fig. 2(b) or 2(d)). The balun 201 may thereby be connected to the first radiating element 101 and the second radiating element 102, and may be used to feed the RF signal to the radiating elements 101, 102.

FIG. 2 shows also that the antenna device 200 may further comprise a reflector 204, which may be arranged on the common axis 103. The reflector 204 is configured to reflect the radio waves from the first radiating element 101 and the second radiating element 102, respectively, into a main radiating direction. Thus, the radiation directivity is increased. The second radiating element 102 may be arranged closer to the reflector 204 than the first radiating element 101. The second radiating element 102 may further have a larger radiating area than the first radiating element 101, to reduce shadowing.

FIG. 2 shows also that the antenna device 200, particularly the feed structure, may comprise a feeding line 202 for feeding the RF signal to the balun 201. The feeding line 202 may be connected to the balun 201 in one or more feeding points. The feed structure of the antenna device 200 may further comprise a support structure, which is configured to hold the first radiating element 101 and the second radiating element 102, such that the radiating elements 101, 102 are arranged on the common axis 103. The feed structure may be at least partly provided on the support structure. For instance, the balun 201 may be provided on the support structure, and/or the feeding line 202 may be at least partly provided on the support structure.

FIG. 3 shows different implementations of an antenna device 100 according to an embodiment of this disclosure, which build on the embodiments shown in FIG 1(a) and 1(b) and FIG. 2. Same elements in these figures are labelled with the same reference signs, and are implemented likewise.

In particular, FIG. 3 shows different examples of the redirecting device 104. For example, one possibility to implement the redirecting device 104 - for example, as a power divider - is to use a single point feed and the balun 201. For example, the redirecting device 104 may comprise the balun 201, and the feeding line 202 may be connected to the balun 201 in a single feeding point 303 (see FIG. 3(a) and 3(c)). In another example, the feeding line 202 may have a first feeding part and a second feeding part, wherein the first feeding part is connected to the balun 201 in a different feeding point 303 than the second feeding part (see FIG. 3(b) and (d)). That is, the feeding line 202 may be connected in two or more feeding points 303 to the balun 201.

Each of the feeding points 303 may be arranged either between the first radiating element 101 and the second radiating element 102 (see FIG. 3(b), 3(c) and 3(d)), or may be arranged between the reflector 204 of the antenna device 100 and the two radiating elements 101, 102 (see FIG. 3(a), 3(b) and 3(c)), or may be arranged from the top of the first radiating element 101. Depending on where the feeding points 303 are arranged, the second phase difference a between the two radiating elements 101, 102 may change, and may accordingly be set by choosing the location of the feeding points 303. Another possible implementation would be to implement the redirecting device 104 first, and to then feed the two radiating elements 101, 102 through two feeding points 303.

The feeding can be realized by coupled feeding. For example, the balun 201 may comprise two conductive parts, which are separated by a gap, and the gap may intersect with the feeding line 202 in one or more feeding points 303. Alternatively, the feeding can be realized by direct feeding (e.g., by a direct metal connection). Overall, the balun 201 may be connected to the feeding line 202 in one or more feeding points 303 by either coupled feeding or direct feeding.

The redirecting device 104 of the antenna device 100 can greatly simplify the feeding of the radiating elements 101, 102, may remove resonances to get a broader bandwidth, may reduce size and cost of the antenna device 100, and may reduce its production complexity.

FIG. 4 shows various exemplary implementations of an antenna device 100 according to an embodiment of this disclosure, which build on the embodiments shown in the previous figures. Same elements in these figures are labelled with the same reference signs, and are implemented likewise.

In particular, FIG. 4(a) shows an antenna device 100, wherein the phase inverter 105 is implemented as a cross-jump structure on the balun 201. FIG. 4(b) shows an antenna device 100, wherein the phase inverter 105 is implemented as a cross-jump structure on the first radiating element 101 (the top radiating element). FIG. 4(c) shows an antenna device 100, wherein the phase inverter 105 is implemented as a cross-jump structure on the first radiating element 101 with a single-point direct-feeding structure. FIG. 4(d) shows an antenna device 100, wherein the phase inverter 105 is implemented as a cross-jump structure on the first radiating element 101 with a die cast balun 201. All the implementations of FIG. 4 have been simulated or measured, and exhibit lower HBW and thus increased directivity than comparable conventional antenna devices.

FIG. 5 and FIG. 6 show an antenna device 100 according to an embodiment of this disclosure in a perspective view and a top view, respectively. The antenna device 100 of FIG. 5 and FIG. 6 builds on the embodiments shown in the previous figures. Same elements in these figures are labelled with the same reference signs, and are implemented likewise.

FIG. 5 shows the antenna device 100 with its two radiating elements 101, 102 arranged on the common axis 103. Further, FIG. 5 shows the balun 201, which is connected to the first radiating element 101 and the second radiating element 101, and shows the feeding line 202 that is connected to the balun 201. FIG. 5 also shows that the first radiating element 101 and the second radiating element 102 may each comprise a substrate 503, and may each comprise two dipole arms in the substrate 503 or on the substrate 503. The first radiating element 101 may specifically comprise a first top dipole arm 501a for a first polarization and a second top dipole arm 501b for a second polarization. The two top dipole arms 501a and 501b may be arranged orthogonal to each other. The second radiating element 102 may specifically comprise a first bottom dipole arm 502a for the first polarization and a second bottom dipole arm 502b for the second polarization. The two bottom dipole arms 502a and 502b may be arranged orthogonal to each other.

FIG. 7 shows further exemplary implementations of an antenna device 100 according to an embodiment of this disclosure, which build on the embodiments shown in the previous figures. Same elements in these figures are labelled with the same reference signs, and are implemented likewise.

In particular, FIG. 7(a) shows an antenna device 100 with the balun 201 provided on the support structure, and with a cross-jump structure implementing the phase inverter 105 on the first radiating element 101. FIG. 7(b) shows an antenna device 100 with a feeding line 201 connected to the balun 201 in one feeding point 303, and a cross-jump structure implementing the phase inverter 105 on the balun 201 near the first radiating element 101.

FIG. 8 shows a method 800 according to an embodiment of this disclosure. The method 800 is suitable for operating an antenna device 100, for instance, the antenna device 100 shown in the previous figures. The antenna device 100 comprises a first radiating element 101 and a second radiating element 102 arranged on a common axis 103. Each radiating element 101, 102 is configured to radiate a radio wave in response to a RF signal fed to the respective radiating element 101, 102.

The method 800 comprises feeding (step 801) the RF signal to the first radiating element 101 and the second radiating element 102. The power of the RF signal is thereby divided (step 802) between the first radiating element 101 and the second radiating element 102. Further, a phase difference of 180° ± a is thereby set (step 803) between the RF signal at the first radiating element 101 and the RF signal at the second radiating element 102, wherein a > 0°. The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed matter, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. An antenna device (100) comprising: a first radiating element (101) and a second radiating element (102) being arranged on a common axis (103), each radiating element (101, 102) being configured to radiate a radio wave in response to a radiofrequency, RF, signal fed to the respective radiating element (101, 102); and a feed structure configured to feed the RF signal to the first radiating element (101) and the second radiating element (102); wherein the feed structure comprises a redirecting device (104) for redirecting power between two or more branches, the redirecting device (104) being configured to distribute the power of the RF signal between the first radiating element (101) and the second radiating element (102); and wherein the feed structure comprises a phase inverter (105) configured to set a quasiinverted phase between the RF signal at the first radiating element (101) and the RF signal at the second radiating element (102) as a first phase difference.

2. The antenna device (100) according to claim 1, wherein the redirecting device (104) is further configured to set a second phase difference (106), in addition to the first phase difference set by the phase inverter (105), between the RF signal at the first radiating element (101) and the RF signal at the second radiating element (102).

3. The antenna device (100) according to claim 2, wherein the redirecting device (104) comprises a first way for providing the RF signal to the first radiating element (101) and a second way for providing the RF signal to the second radiating element (102), wherein the second phase difference (106) is set by the first way having a different lengths than the second way.

4. The antenna device (100) according to one of the claims 1 to 3, wherein the redirecting device (104) of the feed structure comprises: a balun (201) connected to the first radiating element (101) and the second radiating element (102); and a feeding line (202) for feeding the RF signal to the balun (201), the feeding line (202) being connected to the balun (201) in a single feeding point (303).

5. The antenna device (100) according to one of the claims 1 to 3, wherein the redirecting device (104) of the feed structure comprises: a balun (201) connected to the first radiating element (101) and the second radiating element (102); and a feeding line (202) for feeding the RF signal to the balun (201), the feeding line having a first feeding part and a second feeding part, and the first feeding part being connected to the balun (201) in a different feeding point (303) than the second feeding part.

6. The antenna device (100) according to claim 4 or 5, wherein the balun (201) comprises two conductive parts separated by a gap, the gap intersecting with the feeding line (202) in one or more feeding points (303).

7. The antenna (100) according to one of the claims 4 to 6, wherein each feeding point (303) is arranged either between the first radiating element (101) and the second radiating element (102), or between a reflector (204) of the antenna device (100) and the two radiating elements (101, 102), or from the top of the first radiating element (101).

8. The antenna device (100) according to one of the claims 4 to 7, wherein the balun (201) is connected to the feeding line (202) in one or more feeding points (303) by either coupled feeding or direct feeding.

9. The antenna device (100) according to one of the claims 1 to 8, wherein the phase inverter (105) comprises a cross-jump-structure, the cross-jump-structure being designed such that a positive pole of the feed structure cross-jumps to a side of a negative pole of the feed structure, and the negative pole of the feed structure cross-jumps to a side of the positive pole of the feed structure.

10. The antenna device (100) according to one of the claims 1 to 9, wherein the phase inverter (105) is arranged either on one of the first radiating element (101) and the second radiating element (102), or on a balun (201) of the feed structure connected to the first radiating element (101) and the second radiating element (102).

11. The antenna device (100) according to one of the claims 1 to 10, further comprising a reflector (204) arranged on the common axis (103) and configured to reflect the radio waves from the first radiating element (101) and the second radiating element (102) into a main radiating direction.

12. The antenna device (100) according to one of the claims 1 to 11, wherein the first radiating element (101) and the second radiating element (102) are arranged in different planes.

13. The antenna device (100) according to claim 12, wherein the different planes are parallel to each other.

14. The antenna device (100) according to one of the claims 1 to 13, wherein the first radiating element (101) and the second radiating element (102) are arranged concentrically on the common axis (103).

15. The antenna device (100) according to one of the claims 1 to 14, wherein the feed structure is configured to feed the RF signal in parallel to the first radiating element (101) and the second radiating element (102).

16. The antenna device (100) according to one of the claims 1 to 15, wherein at least one of the first radiating element (101) and the second radiating element (102) is a dual-polarized radiating element.

17. The antenna device (100) according to one of the claims 1 to 16, wherein one of the first radiating element (101) and the second radiating element (102) is arranged closer to a reflector (204) of the antenna device (100) than the other radiating element (102, 101) and has a larger radiating area than the other radiating element (102, 101).

18. The antenna device (100) according to one of the claims 1 to 17, further comprising a support structure configured to hold the first radiating element (101) and the second radiating element (102) such that both radiating elements (101, 102) are arranged on the common axis (103).

17

19. The antenna device (100) according to claim 18, wherein the feed structure is at least partly provided on the support structure.

20. A method (800) of operating an antenna device (100) comprising a first radiating element (101) and a second radiating element (102) being arranged on a common axis (103), each radiating element (101, 102) being configured to radiate a radio wave in response to a radiofrequency, RF, signal fed to the respective radiating element (101, 102), wherein the method (800) comprises: feeding (801) the RF signal to the first radiating element (101) and the second radiating element (102); wherein the power of the RF signal is divided between the first radiating element (101) and the second radiating element (102); and wherein a phase difference of 180° ± a is set between the RF signal at the first radiating element (101) and the RF signal at the second radiating element (102), wherein a > 0°.

18