Radiator assembly and antenna system

Abstract

A radiator assembly is disclosed. The assembly comprises: two pairs of radiator elements, each having a feeding interface and a radiator portion extending in a first plane; and a feeding structure including a dielectric substrate carrying two groups of conductive track segments. Each group is associated one pair of radiator elements, and the conductive track segments comprise a first feed segment and a first coupling segment arranged on opposite sides of the dielectric substrate, wherein {i} at least one of the conductive track segments extends in parallel to the first plane(s) and / or {ii} at least one of the conductive track segments lies above the first plane(s) and at least one of the conductive track segments lies below the first plane(s). An antenna assembly is also disclosed.

Description

[0001] Radiator assembly and antenna system

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a radiator assembly comprising a dual-polarization radiator. An antenna system comprising a plurality of such radiator assemblies is also disclosed.

[0004] BACKGROUND

[0005] Over the last years, requirements on wireless communication techniques have increased significantly. In the field of mobile communications, network coverage for user equipment, UE, such as mobile phones is typically provided by deploying base stations, BS. The BSs are equipped with special antenna systems enabling wireless data exchange with the UEs. A suitable antenna system for such a base station may comprise a plurality of radiators, each of which is being fed via a respective feeding structure.

[0006] BSs for mobile communication systems are often required to support a plurality of frequency bands in a frequency range between 400 MHz to 10 GHz. Such BSs may therefore comprise multiple antenna arrays and / or subarrays to operate at distinct frequency bands such as 619-960 MHz, 1710-2700 MHz, 3400-3800 MHz, 5.1-5.8 GHz. As the space inside a housing of a BS is limited, these (sub-)arrays may be arranged in an interleaved (e.g., overlapped) manner, which may require sophisticated feeding structures for the individual radiators of the arrays. Some or all of these (sub-)arrays may be realised as active antennas, having integrated transceivers. Typically, low band (sub-)arrays are realised as passive structures, whereas high band (sub-)arrays can be realised as active antenna arrays.

[0007] BS for new mobile communication systems may need to support massive multiple input multiple output (MIMO) techniques and use different two-dimensional antenna (sub-)arrays for the different frequency bands. The requirement to integrate all these components in the limited space inside such a single base station (e.g., under one and the same antenna radome) is challenging.

[0008] WO 2023 / 061581 Al discloses a BS for multiband operation, in which low band radiators are fed from their side. This approach generally enables a compact arrangement of radiators that are stacked over one another under a same radome. Preferably, a base station antenna is produced at low cost. This requires use of costefficient feeding structures for the antenna systems. It may also be desirable to enable the feeding structure to be easily assembled with its radiator. In case a dualpolarization radiator is to be fed via the feeding structure, the feeding structure may need to be designed such that cross-polarization interference is reduced and a high isolation between the both polarizations is achieved It may also be desired to design the feeding structure such that a symmetrical radiation pattern is provided.

[0009] SUMMARY

[0010] There is a need for a technique that solves one or more of the above or other problems.

[0011] According to as first aspect, a radiator assembly (e.g., for a dual- or multiband antenna or BS) is disclosed. The radiator assembly comprises a dual-polarization radiator including two pairs of radiator elements. Each pair is associated with a pairspecific polarization direction. Each radiator element has a feeding interface and a radiator portion extending away from the feeding interface in a first plane. The radiator assembly further comprises a feeding structure configured to provide feed signals to the dual-polarization radiator. The feeding structure includes a dielectric substrate extending upwards from a second plane toward the dual-polarization radiator and positioning the dual-polarization radiator in a predefined pose above the second plane. The dielectric substrate carries two groups of conductive track segments. Each group of conductive track segments is associated with one pair of the two pairs of radiator elements. The conductive track segments of each group comprise {i} a first feed segment of an open-ended feed line and {ii} a first coupling segment configured to be electrically connected to a ground potential. The first feed segment and the first coupling segment are arranged on opposite sides of the dielectric substrate such that the first coupling segment is capacitively coupled to the first feed segment via the dielectric substrate. The first coupling segment is electrically coupled to the feeding interface of one of the radiator elements of the associated pair of radiator elements.

[0012] At least one of the conductive track segments extends in parallel to the first plane(s) of one or more of the radiator portions. Alternatively, or in addition, at least one of the conductive track segments lies above the first plane(s) of (e.g., the) one of more of the radiator portions and at least one of the conductive track segments lies below the first plane(s) of the one or more of the radiator portions.

[0013] At least two of the conductive track segments (e.g., two of the feed segments and / or two of the coupling segments) may be arranged such that they embrace the dualpolarization radiator. At least two of the conductive track segments may form a symmetrical feeding arrangement. The feeding structure may be configured to feed a first pair of the two pairs of radiator elements from a top side (e.g., of the dualpolarization radiator and / or of the first plane) and a second pair of the two pairs of radiator elements from a bottom side (e.g., of the dual-polarization radiator and / or of the first plane).

[0014] The dual-polarization radiator may be configured as a cross-polarization radiator. Each of the two pairs of radiator elements may form a dipole. Each radiator element may be a half of a dipole. Each dipole may be associated with a dipole-specific polarization and / or a dipole-specific polarization direction. For example, a first pair of the two pairs of radiator elements is associated with a first polarization direction and a second pair of the two pairs of radiator elements is associated with a second polarization direction differing from (e.g., being orthogonal to) the first polarization direction. It is noted that the term "dipole" as used herein is not limited to linear radiator elements, but covers various designs of the radiator elements. For example, double-loop arrangements formed by two radiator elements that each have the form of a loop are considered to fall within the meaning of the term "dipole". Other layouts and shapes of the radiator elements are also deemed to be covered by the term "dipole".

[0015] The feeding interfaces may be arranged at a central portion of the dual-polarization radiator, for example adjacent to one another. The radiator portions may extend away from the central portion. The dual-polarization radiator may comprise a (e.g., dielectric) substrate carrying the feeding interfaces and the two pairs of radiator elements. The substrate of the dual-polarization radiator may be planar. A (e.g., upper) surface of the substrate of the dual-polarization radiator may define the first planes of the radiator portions.

[0016] The dual-polarization radiator may be in (e.g., mechanical and / or electrical) contact with only the feeding structure. The feeding structure may be configured to hold the dual-polarization radiator in the predefined pose. The feeding structure may thus be referred to as having a dual-function by not only being configured to provide feed signals to the dual-polarization radiator, but also mounting the dual-polarization radiator in the predefined pose relative to the second plane. The second plane may correspond to or be parallel to a reflector plane (e.g., of a reflector associated with the dual-polarization radiator). The feeding structure may be configured to be electrically coupled to an electrical interface such that feed signals can be provided to the open-ended feed lines. The feeding structure may be or comprise a printed circuit board, PCB. The dielectric substrate of the feeding structure may be planar and arranged non-parallel to the first plane(s). For example, the (e.g., dielectric substrate of the) feeding structure may be arranged perpendicular to one or more of the first planes. The (e.g., dielectric substrate of the) feeding structure may be arranged perpendicular to the second plane and / or the substrate of the dualpolarization radiator.

[0017] One or more or each of the conductive track segments may be linear. The conductive track segments may be arranged on one or both surfaces of the dielectric substrate of the feeding structure. A first group of the two groups of conductive track segments may be associated with the first polarization direction and a second group of the two groups of conductive tracks may be associated with the second polarization direction.

[0018] The open-ended feed line may comprise a first end configured to be fed with a feed signal. The first end may be located at an edge of the dielectric substrate of the feeding structure. The first end may be located at the second plane. The open-ended feed line may further comprise a second end arranged on the dielectric substrate. The second end may be configured to remain free from (e.g., galvanic) contact with another component and / or may be configured as open end of the open-ended feed line. The second end may be arranged distant from the second plane (e.g., near the first plane(s)). Each open-ended feed line may be entirely arranged on one side of the dielectric substrate.

[0019] The first feed segment may be parallel to the first coupling segment. The first feed segment may overlap the first coupling segment entirely or at least partially in a view normal to the dielectric substrate of the feeding structure. The first coupling segment may overlap the first feed segment entirely or at least partially in a view normal to the dielectric substrate of the feeding structure.

[0020] The at least one of the conductive track segments that lies above the first plane(s) may be associated with a (e.g., the) first pair of the two pairs of radiator elements and / or with the first radiation direction. The at least one of the conductive track segments that lies below the first plane(s) may be associated with a (e.g., the) second pair of the two pairs of radiator elements and / or with the second radiation direction. For example, all conductive track segments of a (e.g., the) first group of the two groups lie above the first plane(s), and all conductive track segments of a (e.g., the) second group of the two groups lie below the first plane(s).

[0021] The conductive track segments of each group may further comprise {iii} a second feed segment of the open-ended feed line and {iv} a second coupling segment configured to be electrically connected to the ground potential. The second feed segment and the second coupling segment may be arranged on opposite sides of the dielectric substrate such that the second coupling segment is capacitively coupled to the second feed segment. The second coupling segment may be electrically coupled to the feeding interface of another one of the radiator elements of the associated pair of radiator elements. The second coupling segment may be arranged such that a direction of travel of a feed signal at the first coupling segment is opposite to a direction of travel of said feed signal at the second coupling segment.

[0022] The second feed segment may be parallel to the second coupling segment. The second feed segment may overlap the second coupling segment entirely or at least partially in a view normal to the dielectric substrate of the feeding structure. The second coupling segment may overlap the second feed segment entirely or at least partially in a view normal to the dielectric substrate of the feeding structure.

[0023] The first feed segment and the second feed segment of a same group may be arranged on a same side of the dielectric substrate and / or parallel to one another. The first feed segment may be connected to the second feed segment via a conductive strip arranged on the dielectric substrate of the feeding structure. The conductive strip may be orthogonal to the first feed segment and the second feed segment. The second end of an open-ended feed line may be defined by and / or correspond to an end of the second feed segment of said open-ended feed line.

[0024] The first coupling segment and the second coupling segment of a same group may be arranged on a same side of the dielectric substrate and / or parallel to one another. The first coupling segment may be connected to the second coupling segment via a conductive patch arranged on the dielectric substrate of the feeding structure. The (e.g., first and / or second) feed segments of different groups may be arranged on different sides of the dielectric substrate. The first feed segment of a (e.g., the) first group of the two groups may be arranged on a first side of the dielectric substrate and the first feed segment of a (e.g., the) second group of the two groups may be arranged on a second side of the dielectric substrate. The first feed segments of different groups may be arranged on different sides of the dielectric substrate. All feed segments of a (e.g., the) first group of the two groups may be arranged on a (e.g., the) first side of the dielectric substrate and all feed segments of a (e.g., the) second group of the two groups may be arranged on a (e.g., the) second side of the dielectric substrate.

[0025] At least one of the (e.g., first and / or second) coupling segments may be electrically coupled to the respective feeding interface via a conductive track portion arranged on the dielectric substrate and extending non-parallel and non-orthogonal to the first plane of the radiator element having the respective feeding interface. The conductive track portion may be connected (e.g., soldered or welded) to the respective feeding interface.

[0026] The conductive track portion and the at least one of the coupling segments electrically coupled to the respective feeding interface via the conductive track portion may be arranged on a same side of the dielectric substrate. In this case, the conductive track portion and the at least one of the coupling segments electrically coupled to the respective feeding interface via the conductive track portion may contact one another or merge into one another.

[0027] The conductive track portion and the at least one of the coupling segments electrically coupled to the respective feeding interface via the conductive track portion may be arranged on opposite sides of the dielectric substrate. In this case, the conductive track portion and the at least one of the coupling segments electrically coupled to the respective feeding interface via the conductive track portion may be electrically connected to one another by a via extending through the dielectric substrate.

[0028] The at least one of the coupling segments may comprise the first coupling segment and the second coupling segment of at least one group (e.g., the first and / or the second group) of the two groups, each of the first coupling segment and the second coupling segment being coupled to the respective feeding interface via a respective conductive track portion arranged on the dielectric substrate. In a first example, the first coupling segment (e.g., of the first and / or the second group) and the conductive track portion via which it is electrically coupled to the respective feeding interface may be arranged on a same side of the dielectric substrate. The second coupling segment (e.g., of the first and / or the second group) and the conductive track portion via which it is electrically coupled to the respective feeding interface may be arranged on opposite sides of the dielectric substrate.

[0029] In a second example, the first coupling segment (e.g., of the first and / or the second group) and the conductive track portion via which it is electrically coupled to the respective feeding interface may be arranged on opposite sides of the dielectric substrate. The second coupling segment (e.g., of the first and / or the second group) and the conductive track portion via which it is electrically coupled to the respective feeding interface may be arranged a same side of the dielectric substrate.

[0030] The conductive track portions associated with and / or connected to respective coupling segments of a (e.g., the) first group of the two groups may be symmetrical to the conductive track portions associated with and / or connected to respective coupling segments of a (e.g., the) second group of the two groups, for example mirror-symmetrical relative to the first plane(s) and / or rotation-symmetrical relative to at least one axis of symmetry lying in the first plane(s).

[0031] The conductive track segments of a (e.g., the) first group of the two groups may be symmetrical to the conductive track segments of a (e.g., the) second group of the two groups, for example mirror-symmetrical relative to the first plane(s) and / or rotation-symmetrical relative to at least one axis of symmetry lying in the first plane(s).

[0032] The at least one of the conductive track segments extending in parallel to the first plane(s) may comprise (e.g., all) the coupling segments of the two groups of conductive track elements. One or more or all of the coupling segments of one or both groups may extend in parallel to the first plane(s).

[0033] Two or more or all of the conductive track segments may extend in parallel to one another.

[0034] The radiator elements may be configured to emit electromagnetic waves with a predefined operating wavelength A, wherein at least one of the conductive track segments has a length I = A I n with n being a natural number. For example, n<8, in particular 3<n<5. In one variant, n=4.

[0035] The coupling segments of one or both of the two groups may be electrically connected to one another. The feeding structure may comprise at least one via or conductive bridge extending through the dielectric substrate. The coupling segments of a (e.g., the) first group of the two groups may be arranged on a (e.g., the) first side of the dielectric substrate and the coupling segments of a (e.g., the) second group of the two groups may be arranged on a (e.g., the) second side of the dielectric substrate. The at least one via or conductive bridge may be part of an electrical connection between (e.g., all) the coupling segments of the first group and the coupling segments of the second group.

[0036] The feeding structure may comprise, for each of the two groups, a (e.g., the) conductive patch arranged on the dielectric substrate, configured to be electrically connected to the ground potential and merging into at least one of the coupling segments of the respective group such that the at least one of the coupling segments of the respective groups extends away from the conductive patch toward the respective feeding interface. The conductive patch may be referred to as grounding patch herein. All coupling elements of a same group of conductive track segments may be connected to and / or merge into a same conductive patch. The coupling elements of different groups of conductive track segments may be connected to and / or merge into different (e.g., group-specific) conductive patches arranged on the dielectric substrate. The conductive patches, when arranged on opposite sides of the dielectric substrate, may be electrically connected to one another by one or more vias extending through the dielectric substrate. The conductive patches may also be referred to as ground planes or ground structures herein. The conductive patches may have a larger width compared with the coupling elements to which they are connected and / or into which they merge.

[0037] The dielectric substrate may be planar. The dielectric substrate may be a substrate of a PCB. The dielectric substrate may comprise {i} a feeding section carrying the conductive track segments and {ii} a connecting section extending from the second plane toward the feeding section. For example, a part of each open-ended feed line is arranged on the connecting section. The first end of one or both open-ended feed lines may be arranged in the connecting section. The second end of one or both open-ended feed lines may be arranged in the feeding section. At least a part of the conductive patches may be arranged on the connecting section.

[0038] The conductive patches may be entirely arranged on the connecting section.

[0039] The connecting section of the planar dielectric substrate may have a curved outline. The connecting section may be formed in the shape of an arc or a step. The connecting section may extend away from the second plane. The connecting section may be configured such that the feeding structure, when attached outside a radiator in the second plane, positions the dual-polarization radiator in the predefined pose above the radiator. The feeding structure may thus be referred to as a side-feeding structure and the dual-polarization radiator may be referred to as a side-fed radiator.

[0040] For example, each group of conductive track segments forms at least a part of a (e.g., group-specific) Marchand balun feed. The feeding structure may comprise a Marchand balun feed for one or both pairs of radiator elements. Such a Marchand balun feed may comprise or consist of the feed segments, the conductive strips, the coupling segments and the conductive track portions associated with one of the pairs of radiator elements. Remainders of the open-ended feed lines (e.g., all portions of the open-ended feed lines except for the feed segments and the conductive strips) may be formed as asymmetric feed lines. The remainders of the open-ended feed lines may be separated from one another by a plurality of vias extending through the substrate of the feeding structure. These vias may connect the conductive patches associated with said feed lines. One Marchand balun feed associated with a first pair of radiator elements may be arranged above the first plane(s) whereas another Marchand balun feed associated with a second pair of radiator elements may be arranged below the first plane(s). Feed signals carried by the open-ended feed line may be capacitively coupled into the first and second coupling segments and thereby reach the radiator elements.

[0041] The dielectric substrate and the dual-polarization radiator may be attached to one another via a slot-in connection. The slot-in connection may be configured such that the dual-polarization radiator is or can be attached to the dielectric substrate by moving it along a longitudinal direction of at least one slot. One of the at least one slot may be arranged in the dielectric substrate of the feeding structure. One of the at least one slot may be arranged in the substrate of the dual-polarization radiator.

[0042] The first planes may be parallel to one another or coincide. The feeding structure may be configured to position the dual-polarization radiator such that the first planes lie parallel to the second plane. The open-ended feed lines, the conductive tracks, the vias, the conductive patches and the conductive strips may be made from (e.g., same or different) electrically conductive material(s) such as a metal or a metal alloy. The dielectric substrate of the feeding structure and / or the substrate of the dual-polarization radiator may be made from a (e.g., same or different) ceramic, polymer (e.g., tetrafluoroethylene, polyimide or epoxide) or composite material such as fiber-reinforced polymer.

[0043] According to as second aspect, an antenna system is provided. The antenna system comprises a reflector arranged in a reflector plane. The antenna system further comprises a plurality of radiator assemblies according to the first aspect. The second planes may be parallel to the reflector plane. The antenna system further comprises a first electrical interface electrically coupled to (e.g., soldered or welded to) the coupling segments of at least one of the radiator assemblies and configured to provide the ground potential for the coupling segments. The antenna system further comprises a second electrical interface electrically coupled to (e.g., soldered or welded to) the open-ended feed lines of at least one of the radiator assemblies and configured to provide feed signals to the open-ended feed lines.

[0044] The antenna system may further comprise a plurality of radiators associated with a first main radiation direction. The plurality of radiator assemblies of the antenna system may be associated with a second main radiation direction corresponding to or being parallel to the first main radiation direction. The plurality of radiators associated with the first main radiation direction may be arranged at a different height above or below the reflector compared with the dual-polarization radiators of the plurality of radiator assemblies of the antenna system.

[0045] The plurality of radiators of the antenna system may be associated with a first operating frequency. The dual-polarization radiators of the plurality of radiator assemblies may be associated with a second operating frequency differing from the first operating frequency. The second operating frequency may be lower than the first operating frequency.

[0046] SHORT DESCRIPTION OF THE FIGURES

[0047] Examples in accordance with the present disclosure are explained below with reference to the figures, wherein: Fig. 1 shows a first perspective view of an exemplary radiator assembly in accordance with the present disclosure;

[0048] Fig. 2 shows a second perspective view of the exemplary radiator assembly;

[0049] Fig. 3 shows a left-side view of a feeding structure of the exemplary radiator assembly;

[0050] Fig. 4 shows a left-side view of the exemplary radiator assembly;

[0051] Fig. 5 shows a right-side view of the feeding structure of the exemplary radiator assembly;

[0052] Fig. 6 shows a right-side view of the exemplary radiator assembly;

[0053] Fig. 7 shows a top view of a dual-polarization radiator of the exemplary radiator assembly;

[0054] Fig. 8 shows a bottom view of the dual-polarization radiator of the exemplary radiator assembly;

[0055] Fig. 9 shows a first detail view of the feeding structure of the exemplary radiator assembly;

[0056] Fig. 10 shows a second detail view of the feeding structure of the exemplary radiator assembly;

[0057] Fig. 11 shows a left-side view of a second variant of the feeding structure in accordance with the present disclosure;

[0058] Fig. 12 shows a right-side view of the second variant of the feeding structure; and

[0059] Fig. 13 schematically illustrates an antenna system in accordance with the present disclosure.

[0060] DETAILED DESCRIPTION Unless indicated otherwise, the reference signs used in the following denote the same or similar structural or functional features. In case an example shows more than one instance of a given entity, which entity is denoted with reference numeral "X", these instances may be referred to either as "X", or as "X-n" with n indicating the particular instance.

[0061] Figures 1 and 2 show different perspective views of a first exemplary radiator assembly 1000 in accordance with the present disclosure. The assembly 1000 comprises a feeding structure 100 and a dual-polarization radiator 200. These components are also shown in views from different sides in Figures 3 to 8.

[0062] The dual-polarization radiator 200 includes a first pair of radiator elements 2-1, 2-3 forming a first dipole associated with a first polarization direction, and a second pair of radiator elements 2-2, 2-4 forming a second dipole associated with a second polarization direction. One may thus say that the respective polarization direction is specific for the given pair of radiator elements 2. In the illustrated example, the first and second polarization direction are orthogonal to one another, although other configurations are possible.

[0063] Each radiator element 2 has a respective feeding interface 4 via which a feeding signal can be fed to the respective radiator element 2. Each radiator 2 further has a respective (e.g., linear or loop-shaped) radiator portion 6 extending away from said feeding interface 4 in a respective first plane 8. In the illustrated example, the first planes 8 of the radiator portions 6-1 to 6-4 are identical. In particular, in the illustrated example, the dual-polarization radiator 200 comprises a dielectric substrate 10 carrying conductive patterns forming the feeding interfaces 4-1 to 4-4 and wave-emitting portions of the radiator elements 2-1 to 2-4. It is also possible for the radiator 200 to comprise four separate substrates, one for each radiator element 2-1 to 2-4. In this case, the first planes 8-1 to 8-4 may be oblique relative to one another.

[0064] The feeding structure 100 is configured to provide feed signals to the dualpolarization radiator 200. The feeding structure 100 includes a dielectric substrate 12 that extends upwards from a second plane 14 to and may extend beyond the first plane(s) 8. The feeding structure 100 can be referred to as a side-feeding structure and positions the dual-polarization radiator 200 in a predefined pose above the second plane 14. In the illustrated example, the feeding structure 100 is configured to position the dual-polarization radiator 200 such that the first planes 8 lie parallel to the second plane 14.

[0065] The dielectric substrate 12 is for example planar and comprises a feeding section 16 and a connecting section 18. The feeding section 16 may be arranged adjacent to the radiator 200. The connecting section 18 may extend from the second plane 14 to the feeding section 16. The connecting section 18 is in the illustrated example formed in the shape of an arc and thus has a curved outline. This enables the dielectric substrate 12 to be attached to a base 20 at a location remote from a planar reflector 23 lying in the second plane 14, while the radiator 200 can still be positioned in the predefined pose above said reflector 20.

[0066] The substrates 10 and 12 may be attached to one another via a slot-in connection. In the illustrated example, the substrate 10 comprises a linear slot 22 extending from an outer edge of the substrate 10. The slot-in connection in this case is configured such that the dual-polarization radiator 200 is attached to the dielectric substrate 12 of the feeding structure 100 by moving it along a longitudinal direction of the slot 22. This enables an easy assembly process.

[0067] The dielectric substrate 12 carries two groups of conductive track segments. In case the feeding structure is a PCB, the conductive track segments may be made from metal or a metal alloy, as is known in the art.

[0068] Each group of conductive track segments is associated with a dipole formed by one pair of radiator elements 2. The conductive track segments of each group in the illustrated example comprise a first feed segment 26 and a second feed segment 28 of an open-ended feed line 30. The first feed segment 26 may be connected to the second feed segment via a conductive strip 32.

[0069] The conductive track segments of each group in the illustrated example further comprise a first coupling segment 34 and a second coupling segment 36. The coupling segments 34, 36 are configured to be electrically connected to a ground potential. Each of the coupling segments 34, 36 is associated with a different one of the feed segments 26, 28. The respective coupling segment 34, 36 is arranged on an opposite side of the substrate 12 than its associated feed segment 26, 28 such that the respective coupling segment 34, 36 is capacitively coupled to the associated feed segment 26, 28 via the dielectric substrate 12. Each of the coupling segments is electrically coupled to a distinct feeding interface 4 of one of the radiator elements 2. Thus, feed signals carried by the open-ended feed lines 30 can be capacitively coupled into the coupling segments 34, 36 that forward said signals to the radiator elements 2.

[0070] According to the present disclosure, at least one of the following conditions is fulfilled:

[0071] {a} at least one of the conductive track segments extends in parallel to the first plane(s) 8 of one or more of the radiator portions 6;

[0072] {b} at least one of the conductive track segments lies above the first plane(s) 8 of one of more of the radiator portions 6 and at least one of the conductive track segments lies below the first plane(s) 8 of the one or more of the radiator portions 6.

[0073] In the illustrated example of Figures 1 to 8, both conditions are fulfilled: all conductive track segments 26, 28, 32, 34 extend in parallel to the first plane 8 that is identical between all radiator portions 6, the feed segments 26-1, 28-1 and their associated coupling segments 34-1, 36-1 associated with a first dipole are arranged below the first plane 8 and the feed segments 26-2, 28-2 and their associated coupling segments 34-2, 36-2 associated with a second dipole are arranged above the first plane 8. That is, in the illustrated example, all conductive track segments 26, 28, 32, 34 that lie below the first plane 8 are associated with a first pair of radiator elements 2-1, 2-3 forming the first dipole and all conductive track segments 26, 28, 32, 34 that lie above the first plane 8 are associated with a second pair of radiator elements 2-2, 2-4 forming the second dipole.

[0074] As can be seen in Figures 1 to 6, the first feed segment 26 and the second feed segment 28 of a same group (e.g., associated with a same dipole and / or polarization direction) can be arranged on a same side of the dielectric substrate 12, and the first coupling segment 34 and the second coupling segment 36 of a same group may be arranged on a same side of the dielectric substrate 12. For example, the feed segments 26-1, 28-1 of the first group are arranged on another side of the substrate 12 than the feed segments 26-2, 28-2 of the second group.

[0075] In the illustrated example, each coupling segment 34, 36 is connected to the respective feeding interface 4 via a conductive track portion 38, 40 arranged on the substrate 12. The conductive track portions 38 each extend oblique to the first plane 8 and may be soldered or welded to their respective feeding interfaces 4. As shown in the zoomed-in view of Figure 9, in which the substrate 12 is not illustrated, conductive track portion 38-1 may be connected to coupling portion 34-1 and may be arranged on an opposite side of the substrate 12 as the coupling portion 34-1. The same may apply to conductive track portion 38-2 and coupling portion 34- 2. On the other hand, conductive track portion 40-1 may be connected to coupling portion 36-1 and may be arranged on a same side of the substrate 12 as the coupling portion 36-1. This may also apply to conductive track portion 40-2 and coupling portion 36-2. Conductive track portions 38-1, 38-2 may be connected to the respective coupling portions 34-1, 34-2 by one or more respective vias 42 extending though the substrate 12.

[0076] The conductive track segments 26, 28, 34, 36, the conductive strips 32 and the conductive track portions 38 are arranged on the feeding section 16 of the substrate 12. A remainder of the open-ended feedline is arranged on the connecting section 18. The feeding structure 100, in particular the feeding section 16, may be configured to be essentially symmetrical. In the illustrated example, the conductive track segments are all parallel to the first plane 8, and the conductive track segments 26, 28, 34, 36 and conductive track portions 38 are arranged symmetrically relative to the first plane 8. The particular arrangement of the conductive track segments 26, 28, 34, 36 and conductive track portions 38 may reduce cross-polarization interference.

[0077] A length of an overlap region between a feed segment 26, 28 and its associated coupling segment 34, 36 may correspond to a quarter wavelength of electromagnetic waves emitted at an operating frequency of one or more of the radiator elements 2. This may enable a high coupling efficiency.

[0078] As the coupling segments 34, 36 are configured to be electrically connected to the ground potential, two or more of the coupling segments 34-1, 34-2, 36-1, 36-2 may be electrically connected to one another, for example by one or more vias 44. In the illustrated example, the coupling segments 34-1, 36-1 merge into a first conductive patch 46-1 and the coupling segments 34-2, 36-2 merge into a second conductive patch 46-2. The conductive patches 46-1, 46-2 may be arranged on opposite sides of the substrate 12 in the connecting section 18 and electrically connected to one another by a plurality of vias 42, as also apparent from the detail view of Figure 10, in which the substrate 10 is not illustrated. As can be seen in Figures 1 to 8, the open-ended feed lines 30-1, 30-2 may differ in length. This may be a direct consequence of the arc-shaped form of the connecting section 18, which leads to one of the feed lines 30 extending along a smaller radius than the other. In order to provide a desired feeding behaviour, the feeding structure 100 may include two Marchand balun feeds, each comprising one of the groups of conductive track segments. The feed segments 26, 28, the conductive strips 32, the coupling segments 34, 36 and the conductive track portions 38, 40 may form two distinct Marchand balun feeds, one for each dipole. The remaining sections of the open-ended feed lines 30 may be formed as asymmetric feed lines.

[0079] Figures 11 and 12 show different side views of a second variant 120 of the feeding structure 100 in accordance with the present disclosure, indicated with reference numeral 120. The first variant is mainly identical to the exemplary assembly 1000 shown in Figs. 1 to 10 and may thus comprise similar features as described above. However, in the second variant, the feed segments 26, 28 are all arranged on a same side of the substrate 12, and the coupling segments 34, 36 are all arranged on an opposite side of the substrate 12.

[0080] Further variants and modifications of the feeding structure 100 are also possible. For example, a first coupling portion 34-1 associated with the first dipole may be arranged on a same side of the substrate 12 as its associated conductive track portion 38-1, whereas a first coupling portion 34-2 may be arranged on an opposite side of the substrate 12 than its associated conductive track portion 38-2. As apparent from the examples described above, the layout of the conductive track segments may be adapted by scaling, widening or narrowing, lengthening or shortening the individual segments, or by adding further (e.g., linear) segments in between. One may also consider using curved segments instead of linear segments.

[0081] Figure 13 schematically illustrates an antenna system 2000 in accordance with the present disclosure. The system 2000 comprises the reflector 23 arranged in a reflector plane that for example corresponds to the second plane 14. The system 2000 further comprises a plurality of the radiator assemblies 1000 described herein. The system 2000 further comprises, for at least one of the assemblies 1000, a first electrical interface 48 electrically, coupled to the coupling segments 34, 36 (e.g., via the conductive patch(es) 46), and configured to provide the ground potential for the coupling segments 34, 36. The system 2000 further comprises, for (e.g., the) at least one of the assemblies 1000, a second electrical interface 50 electrically coupled to the open-ended feed lines 30 and configured to provide feed signals to the open- ended feed lines 30.

[0082] The antenna system 2000 may further comprise a plurality of radiators associated with a first main radiation direction, wherein the plurality of radiator assemblies 1000 of the system 2000 is associated with a second main radiation direction corresponding to the first main radiation direction. The plurality of radiators may be arranged at different (e.g., lower) heights above or below the reflector 23 compared with the dual-polarization radiators 200 of the plurality of radiator assemblies 1000.

[0083] In the example of Figure 13, the system 2000 comprises a first plurality of radiators 300 forming a high midband antenna array (e.g., operating frequency between 3.4- 3.7 GHz), a second plurality of radiators 400 forming a lower midband antenna array (e.g., operating frequency 1710-21701 MHz), and the plurality of radiator assemblies 1000 forming a low-band antenna array (e.g., operating frequency 700-960 MHz). That is, the radiators of the assemblies 1000 and the radiators of the pluralities 300, 400 may have different operating frequencies. The dual-polarization radiators 200 of the assemblies 1000 of the system 2000 may be arranged in a radiation path of the radiators of the pluralities 300, 400. The dual-polarization radiators 200 may be designed as transparent radiators, which means that waves emitted by the higher frequency radiators of the pluralities 300, 400 may be transmitted through the radiators 200 without major disturbances (e.g., a damping of less than 10, 5 or 3 dB).

[0084] As shown in Fig. 13, the feeding structure 100, 120 enables the comparatively large dual-polarization radiators 200 to be positioned above the reflector 200 without the feeding structure 100 needing to be attached in the area of the reflector 200 used by the radiators of the pluralities 300, 400 and the dual-polarization radiators 200 of the assemblies 1000, but rather outside thereof. This approach is also feasible when using a frequency selective surface (FSS) instead of a common reflector 23 and arranging the plurality of radiators 300 and / or 400 below said FSS and the radiators 200 above said FSS.

[0085] Details of the technique disclosed herein will now be explained in other words to provide a better understanding of the present disclosure.

[0086] A multiband multicolumn array antenna (e.g., the system 2000) may comprise different radiators for different frequency ranges (e.g. Low-Band (LB, 612 / 698- 894 / 960 MHz), Low-Mid-Band (LMB, 1427 / 1695 - 2200 / 2700 MHz) and High-Mid- Band (HMB, 3.2 / 3.3-4 / 4.2 GHz). As shown in Figure 13, all the radiators can be arranged over one common (e.g., shared) reflector 23. Alternatively, a frequency selective structure, FSS, may be used that serves as a reflector for operating frequencies of subsets of the radiators, and only these subsets of radiators may be arranged above the FSS whereas other radiators are located below the FSS. In order to reduce the effect of LB radiators on LMB and HMB radiators, transparent LB radiators may be employed, for example by introducing LC-structures into the radiator. Like this, the LMB and HMB arrays may be developed separately and ideally behave identically with and without LB radiators on top. For a configuration with common reflector 23, it may be advantageous to feed the LB radiator from the side, because then the LB and LMB / HMB radiators can be arranged independent from each other (e.g. the LB radiators do not have to be in between two columns of LMB, or LB system spacing (vertically) does not have to be twice of LMB system spacing). For an FSS configuration, the feed signals may also be provided from the side of the radiators, because there is may be insufficient space below the FSS, as this space may be occupied by the active antenna system, AAS. One may thus consider either using a side feeding of the LB dipole or using a combination of a center feeding and a crossing outside with some signal distribution line (e.g., PCB, cable, metal strip). Overall, a side fed LB radiator may be suitable for both configurations and therefore help to reduce development effort and cost because only one variant of LB is needed.

[0087] If the radiator is side fed with two crossed PCB baluns or two PCB baluns at each corner, it is more expensive than feeding with one single PCB and also in case the connection to the signal distribution has to be done on the side (e.g., in the FSS case), the two polarizations may not be not connected at the same positions, which may increase complexity for the signal distribution.

[0088] If there is a direct feeding of the radiator (i.e. the signal line is connected to one of the loops and the ground connected to the other loop for that polarization) it may be difficult to achieve a good matching, also the length of the feeding line can be important for generating some effect on the radiator at specific lengths (quarterwave, half-wave). Therefore, it may be advantageous to use a Marchand balun for feeding the dipole.

[0089] The solution described herein may enable a side feeding of the dual-polarization radiator 200 with a single PCB in the form of feeding structure 100, 120. Feeding may be provided by providing a feeding of Marchand balun type. Slots between coupling segments and conductive patches (e.g., within one polarization and between different polarizations) may be electrically shorted (e.g., using vias) to mitigate resonance issues. By providing a feeding from below and from above the dual-polarization radiator 200, coupling between the two polarizations may be reduced and to identical feeding situations for both polarizations may be provided.

[0090] The feeding structure 100 may comprise two unsymmetrical feed lines that are connected to respective Marchand balun feeds. The two unsymmetrical feed lines together with feed segments 26, 28 and the conductive strips 32 included in the Marchand balun feeds may form the two open-ended feed lines 30-1, 30-2. In this case, one may say that the open-ended feed lines 30 comprise first portions forming unsymmetrical feed lines and second portions that are part of the Marchand balun feeds. The first portions and second portions may join one another at a connection point at which a conductive patch 16-1 or a coupling segment 34-1, 36-1 associated with one of the feed lines 30-1 is shorted to a conductive patch 16-2 or a coupling segment 34-2, 36-2 associated with the other one 30-2 of the feed lines. This connection point may be spaced apart from the interfaces 4 by approximately a quarter wavelength.

[0091] The technique disclosed herein may mitigate resonance effects that would lead to problems in radiation pattern and isolation. By providing nearly identical feeding situations for both polarizations, identical matching configuration and losses as well as identical radiation patterns may be provided. Furthermore, no additional parts may be needed for improved decoupling between the two polarizations.

[0092] Using wideband transparent loop radiators means that there is always some frequency range where a gap in between two loops is resonating. If there are two parallel Marchand baluns closely below this gap, they may also be resonating to some extent, having effects on isolation and pattern performance of the dipole. This coupling may be reduced by arranging the two polarizations on different layers of the substrate 12 and putting a via wall in between. Also, the grounds of each Marchand balun may be connected to shorten the gap between them so that there is no additional resonance and return loss is improved. Additionally, inner ground stripes of the two Marchand baluns may also connected to avoid a common mode resonance between the two polarizations and to shorten that gap accordingly. Also, the two polarizations may behave differently because of an asymmetry in the feed lines 30, including a different position of the short between the two polarizations relative to the entire length of the feed line. As described herein, within the part 16 that is in close vicinity of the dual-polarization radiator 200, the conductive track segments of the two polarizations have a largely identical layout.

[0093] Various modifications and advantages of the technique disclosed herein may become apparent to those skilled in the art.

Claims

Claims1. A radiator assembly (1000), comprising: a dual-polarization radiator (200) including two pairs of radiator elements (2), each pair being associated with a pair-specific polarization direction, each radiator element (2) having a feeding interface (4) and a radiator portion (6) extending away from the feeding interface (4) in a first plane (8); and a feeding structure (100; 120) configured to provide feed signals to the dualpolarization radiator (200), the feeding structure (100; 120) including a dielectric substrate (12) extending upwards from a second plane (14) toward the dualpolarization radiator (200) and positioning the dual-polarization radiator (200) in a predefined pose above the second plane (14), the dielectric substrate (12) carrying two groups of conductive track segments, each group of conductive track segments being associated with one pair of the two pairs of radiator elements (2) and the conductive track segments of each group comprising {i} a first feed segment (26) of an open-ended feed line (30) and {ii} a first coupling segment (34) configured to be electrically connected to a ground potential, the first feed segment (26) and the first coupling segment (34) being arranged on opposite sides of the dielectric substrate (12) such that the first coupling segment (34) is capacitively coupled to the first feed segment (26) via the dielectric substrate (12), the first coupling segment (34) being electrically coupled to the feeding interface (4) of one of the radiator elements (2) of the associated pair of radiator elements (2), wherein {a} at least one of the conductive track segments extends in parallel to the first plane(s) (8) of one or more of the radiator portions (6) and / or {b} at least one of the conductive track segments lies above the first plane(s) (8) of one of more of the radiator portions (6) and at least one of the conductive track segments lies below the first plane(s) (8) of the one or more of the radiator portions (6).

2. The radiator assembly (1000) of claim 1, wherein the at least one of the conductive track segments that lies above the first plane(s) (8) is associated with a first pair of the two pairs of radiator elements (2), and wherein the at least one of the conductive track segments that lies below the first plane(s) (8) is associated with a second pair of the two pairs of radiator elements (2).

3. The radiator assembly (1000) of claim 2, wherein all conductive track segments of a first group of the two groups lie above the first plane(s) (8), andwherein all conductive track segments of a second group of the two groups lie below the first plane(s) (8).

4. The radiator assembly (1000) of any one of claims 1 to 3, wherein the conductive track segments of each group further comprise {iii} a second feed segment (28) of the open-ended feed line (30) and {iv} a second coupling segment (36) configured to be electrically connected to the ground potential, the second feed segment (28) and the second coupling segment (36) being arranged on opposite sides of the dielectric substrate (12) such that the second coupling segment (36) is capacitively coupled to the second feed segment (28), the second coupling segment (36) being electrically coupled to the feeding interface (4) of another one of the radiator elements (2) of the associated pair of radiator elements (2).

5. The radiator assembly (1000) of claim 4, wherein the first feed segment (26) and the second feed segment (28) of a same group are arranged on a same side of the dielectric substrate (12) and / or wherein the first coupling segment (34) and the second coupling segment (36) of a same group are arranged on a same side of the dielectric substrate (12).

6. The radiator assembly (1000) of any one of claims 1 to 5, wherein the first feed segment (26-1) of a first group of the two groups is arranged on a first side of the dielectric substrate (12) and the first feed segment (26-2) of a second group of the two groups is arranged on a second side of the dielectric substrate (12).

7. The radiator assembly (1000) of any one of claims 1 to 6, wherein at least one of the coupling segments (34, 36) is electrically coupled to the respective feeding interface (4) via a conductive track portion (38, 40) arranged on the dielectric substrate (12) and extending non-parallel and non-orthogonal to the first plane (8) of the radiator element (2) having the respective feeding interface (4).

8. The radiator assembly (1000) of claim 7, wherein the conductive track portion (38, 40) and the at least one of the coupling segments (34, 36) electrically coupled to the respective feeding interface (4) via the conductive track portion (38, 40) are arranged on opposite sides of the dielectric substrate (12).

9. The radiator assembly (1000) of claim 8, wherein the conductive track portion (38, 40) and the at least one of the coupling segments (34, 36) electrically coupled to the respective feeding interface (4) via the conductive track portion (38, 40) areelectrically connected to one another by a via (42) extending through the dielectric substrate (12).

10. The radiator assembly (1000) of any one of claims 7 to 9 and at least claim 4, wherein the at least one of the coupling segments (34, 36) comprises the first coupling segment (34-1, 36-1) and the second coupling segment of at least one group of the two groups, each of the first coupling segment (34-1) and the second coupling segment (36-1) being coupled to the respective feeding interface (4-1, 4-3) via a respective conductive track portion (38-1, 40-1) arranged on the dielectric substrate (12), wherein the first coupling segment (34-1) and the conductive track portion (38-1) via which it is electrically coupled to the respective feeding interface (4-1) are arranged on a opposite sides of the dielectric substrate (12) whereas the second coupling segment (36-1) and the conductive track portion (40-1) via which it is electrically coupled to the respective feeding interface (4-3) are arranged on a same side of the dielectric substrate (12).

11. The radiator assembly (1000) of any one of claims 7 to 10, wherein the conductive track portions (38-1, 40-1) associated with respective coupling segments (34-1, 36-1) of a first group of the two groups are symmetrical to the conductive track portions (38-2, 40-2) associated with respective coupling segments (34-2, 36- 2) of a second group of the two groups, in particular mirror-symmetrical relative to the first plane(s) and / or rotation-symmetrical relative to at least one axis of symmetry lying in the first plane(s).

12. The radiator assembly (1000) of any one of claims 1 to 11, wherein the conductive track segments of a first group of the two groups are symmetrical to the conductive track segments of a second group of the two groups, in particular mirror- symmetrical relative to the first plane(s) and / or rotation-symmetrical relative to at least one axis of symmetry lying in the first plane(s).

13. The radiator assembly (1000) of any one of claims 1 to 12, wherein the at least one of the conductive track segments extending in parallel to the first plane(s) comprises the coupling segments (34, 36) of the two groups of conductive track elements.

14. The radiator assembly (1000) of any one of claims 1 to 13, wherein two or more or all of the conductive track segments extend in parallel to one another.

15. The radiator assembly (1000) of any one of claims 1 to 14, wherein the radiator elements (2) are configured to emit electromagnetic waves with a predefined operating wavelength A, wherein at least one of the conductive track segments has a length I = A I n with n being a natural number such as 4.

16. The radiator assembly (1000) of any one of claims 1 to 15, wherein the coupling segments (34, 36) of one or both of the two groups are electrically connected to one another.

17. The radiator assembly (1000) of claim 16 and at least claim 6, wherein the feeding structure (100; 120) comprises at least one via (44) extending through the dielectric substrate (12), wherein the coupling segments (34-1, 36-1) of a first group of the two groups are arranged on a first side of the dielectric substrate (12) and the coupling segments (34-2, 36-2) of a second group of the two groups are arranged on a second side of the dielectric substrate (12), and wherein the at least one via (44) is part of an electrical connection between the coupling segments (34-1, 36-1) of the first group and the coupling segments (34-2, 36-3) of the second group.

18. The radiator assembly (1000) of any one of claims 1 to 17, wherein the feeding structure (100; 120) comprises, for each of the two groups, a conductive patch (46) arranged on the dielectric substrate (12), configured to be electrically connected to the ground potential and merging into at least one of the coupling segments (34, 36) of the respective group such that the at least one of the coupling segments (34, 36) of the respective groups extends away from the conductive patch (46) toward the respective feeding interface (4).

19. The radiator assembly (1000) of any one of claims 1 to 18, wherein the dielectric substrate (12) is planar and comprises {i} a feeding section (16) carrying the conductive track segments and {ii} a connecting section (18) extending from the second plane (14) toward the feeding section (16), wherein a part of each open- ended feed line (30) is arranged on the connecting section (18).

20. The radiator assembly (1000) of claims 18 and 19, wherein at least a part of the conductive patches (46) are arranged on the connecting section (18).

21. The radiator assembly (1000) of claim 19 or 20, wherein the connecting section (18) of the planar dielectric substrate (12) has a curved outline.

22. The radiator assembly (1000) of any one of claims 1 to 21, wherein each group of conductive track segments forms at least a part of a group-specific Marchand balun feed.

23. The radiator assembly (1000) of any one of claims 1 to 22, wherein the dielectric substrate (12) and the dual-polarization radiator (200) are attached to one another via a slot-in connection, the slot-in connection being configured such that the dual-polarization radiator (200) is attached to the dielectric substrate (12) by moving it along a longitudinal direction of a slot (22).

24. The radiator assembly (1000) of any one of claims 1 to 23, wherein the first planes (8) are parallel to one another or coincide, and wherein the feeding structure (100; 120) is configured to position the dual-polarization radiator (200) such that the first planes (8) lie parallel to the second plane (14).

25. An antenna system (2000) comprising: a reflector (23) arranged in a reflector plane; a plurality of radiator assemblies (1000) according to any one of the preceding claims, the second planes (14) being parallel to the reflector plane; and a first electrical interface (48) electrically coupled to the coupling segments (34, 36) of at least one of the radiator assemblies (1000) and configured to provide the ground potential for the coupling segments (34, 36); and a second electrical interface (50) electrically coupled to the open-ended feed lines (30) of at least one of the radiator assemblies (1000) and configured to provide feed signals to the open-ended feed lines (30).

26. The antenna system (2000) of claim 25, further comprising: a plurality of radiators (300; 400)associated with a first main radiation direction, wherein the plurality of radiator assemblies (1000) is associated with a second main radiation direction corresponding to the first main radiation direction, and wherein the plurality of radiators (300; 400) associated with the first main radiation direction is arranged at a different height above or below the reflector (23) compared with the dual-polarization radiators (200) of the plurality of radiator assemblies (1000).Abstract

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