Dual-polarized antenna structure

Abstract

The present disclosure relates to a dual-polarized antenna structure (400). The dual-polarized antenna structure (400) comprises a first radiating unit (200) having a first polarization and a second radiating unit (300) having a second polarization, wherein the first polarization is orthogonal to the second polarization. The first radiating unit (200) comprises a first feeding network (202) arranged on a first side (206a) of a first substrate (204), and a tapered-slot antenna array (208) arranged on a second side (206b) of the first substrate (204) opposite to the first side (206a), wherein the tapered-slot antenna array (208) comprises a plurality of tapered-slot elements (210a-d) distributed in a circumferential direction of the tapered-slot antenna array (208). The second radiating unit (300) comprises a dipole antenna (308a) arranged on a second substrate (304), wherein the dipole antenna (308a) comprises a first dipole element (310a) extending in a first direction and a second dipole element (310b) extending in a second direction opposite to the first direction. The second radiating unit (300) is arranged to extend through a central portion (212) of the first radiating unit (200), such that the first and second dipole element (310a, 310b) of the second radiating unit (300) are arranged at a respective side of the first substrate (204) of the first radiating unit (200). The present disclosure further related to an antenna comprising the antenna structure, and a base station comprising the antenna structure.

Description

[0001] DUAL-POLARIZED ANTENNA STRUCTURE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to the field of antenna technology, particularly to a dual-polarized antenna structure, as well as a base station comprising said antenna structure.

[0004] BACKGROUND

[0005] Antennas are known in the art and used to convert radio frequency fields into alternating current or converting alternating current in to propagating waves at radio frequencies. The radio frequency wave (or electromagnetic wave of certain frequencies) has a polarization, which refers to the direction of the electric field of the signal. More specifically, the polarization can refer to an orientation of the plane of the electric field from a perspective of looking at it from the transmitter of the signal.

[0006] A dual-polarized antenna is an antenna that is capable of receiving and transmitting electromagnetic waves with two distinct forms of polarization, typically horizontal and vertical polarization. These antennas have been developed to overcome some of the limitations of single-polarized antennas, which include limited ability to efficiently transmit and receive signals in diverse scenarios where signal orientations may vary.

[0007] Moreover, dual-polarized antennas have gained popularity due to their ability to enhance communication reliability, mitigate signal interference, and support a broader range of applications, mainly due to enabling simultaneous transmission and reception of signals with different polarizations.

[0008] Dual-polarized antennas are today typically realized by having a horizontally-polarized radiating unit either above or below a vertically-polarized radiating unit, or above a reflector. However, existing solutions face challenges such as increased complexity in design, manufacturing, and deployment, as well as larger footprint and limitations in achieving optimal performance across a wide frequency range. These challenges can impact the overall efficiency and cost-effectiveness of the antenna systems.

[0009] Therefore, there is a need for a new and improved dual-polarized antenna structure that overcomes the limitations of existing designs.

[0010] SUMMARY

[0011] The herein disclosed technology seeks to mitigate, alleviate, or eliminate one or more deficiencies and disadvantages in the prior art singly or in any combination. The presently disclosed technology addresses these challenges by providing a dual-polarized antenna structure, and a base station comprising such antenna structure as defined in the appended claims. The presently disclosed technology may improve transmission / reception performance, reduce complexity, and enhance the adaptability of the antenna across various communication scenarios. Moreover, the proposed antenna structure may provide for a compact design as well as a stackable structure for achieving higher gain. The proposed antenna structure may further achieve an omnidirectional radiation pattern.

[0012] The disclosed technology finds application in various wireless communication systems, including but not limited to, telecommunications, satellite communication, and other wireless networking technologies.

[0013] The presently disclosed technology is at least partly based on the insight that the two radiating units of the dual-polarized antenna can be provided in an integrated manner through the specific structure proposed herein, which can result in the two radiating units of different polarization having similar radiation patterns, and a common phase center.

[0014] Various aspects and embodiments of the technology disclosed herein are defined below and in the accompanying independent and dependent claims.

[0015] According to a first aspect, there is provided a dual-polarized antenna structure comprising a first radiating unit having a first polarization and a second radiating unit having a second polarization. The first polarization is orthogonal to the second polarization. The first radiating unit comprises a first feeding network arranged on a first side of a first substrate, and a tapered-slot antenna array arranged on a second side of the first substrate opposite to the first side. The tapered-slot antenna array comprises a plurality of tapered-slot elements distributed in a circumferential direction of the tapered-slot antenna array. The second radiating unit comprises a dipole antenna arranged on a second substrate. The dipole antenna comprises a first dipole element extending in a first direction and a second dipole element extending in a second direction opposite to the first direction. The second radiating unit is arranged to extend through a central portion of the first radiating unit, such that the first and second dipole element of the second radiating unit are arranged at a respective side of the first substrate of the first radiating unit.

[0016] According to a second aspect, there is provided an antenna comprising the dual-polarized antenna structure according to any embodiments of the first aspect. The antenna further comprises a plurality of feeding lines connected to the antenna structure, and configured to feed the antenna structure with a driving signal. With this second aspect of the disclosed technology, similar advantages and features are present as in the other aspects. In order to avoid undue repetition, reference is made to the above. According to a third aspect, there is provided a base station comprising the dual-polarized antenna structure according to any embodiments of the first aspect. Alternatively, the base station may comprise the antenna according to any embodiments of the second aspect. With this third aspect of the disclosed technology, similar advantages and features are present as in the other aspects. In order to avoid undue repetition, reference is made to the above.

[0017] The disclosed aspects and example embodiments may be suitably combined with each other in any manner apparent to anyone of ordinary skill in the art, such that one or more features or embodiments disclosed in relation to one aspect may also be considered to be disclosed in relation to another aspect or embodiment of another aspect.

[0018] Further embodiments are defined in the dependent claims. It should be emphasized that the term "comprises / comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components. It does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0019] A possible associated advantage of some embodiments is that it may provide for space diversity, meaning it allows for arranging several radiating units within a distance of approximately 0.5 to 1 times a wavelength of the transmitted signals. This can be achieved by the compact structure and integration of the different radiating elements. More specifically, the herein proposed design of the tapered-slot antenna array provides for arrangement of two such antenna arrays within one wavelength of each other, while still achieving desirable isolation between them.

[0020] A further possible advantage of some embodiments is that a compact placement of connectors and cables can be achieved, by the proposed arrangement of the first and second radiating unit (and any further radiating units in a stacked antenna structure).

[0021] A further possible advantage some embodiments is that it may be scalable for a wide range of frequencies, as well as providing a robust design which can be easy to manufacture with high tolerances.

[0022] A further possible advantage of some embodiments is that the antenna structure may be stackable so as to increase a gain of the antenna structure. This may be partly because of the radiating units having different polarizations can have a common phase center, and also due to a design of the feeding of the radiating units allowing for a stacked configuration. These and other features and advantages of the present disclosure will in the following be further clarified with reference to the embodiments described hereinafter.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The foregoing will be apparent from the following more particular description of the example embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views, unless otherwise stated. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the example embodiments. In the drawings:

[0025] Figure 1 illustrates, by way of example, an antenna structure in accordance with some embodiments.

[0026] Figure 2A and 2B illustrates, by way of example, a respective side of a first radiating unit of the antenna structure in accordance with some embodiments.

[0027] Figure 3A and 3B illustrates, by way of example, a respective side of a second radiating unit of the antenna structure in accordance with some embodiments.

[0028] Figure 4A and 4B illustrates, by way of another example, the antenna structure in accordance with some embodiments.

[0029] Figure 5A and 5B illustrates, by way of example, two radiating units on a common substrate from a respective side, in accordance with some embodiments.

[0030] Figure 6 illustrates, by way of example, an antenna system of a base station, in accordance with some embodiments.

[0031] Figure 7A and 7B illustrates, by way of yet another example, a respective side of a first radiating unit of the antenna structure in accordance with some embodiments.

[0032] Figure 8 schematically illustrates a base station in accordance with some embodiments.

[0033] DETAILED DESCRIPTION

[0034] The present disclosure is described below with reference to the accompanying drawings, in which certain aspects of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like numbers refer to like elements throughout the description. It is to be understood that the present disclosure is not limited to the embodiments described herein and illustrated in the drawings; rather, those skilled in the art will recognize that many changes and modifications may be made within the scope of the appended claims.

[0035] It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may refer to more than one unit in some contexts, and the like. Furthermore, the words "comprising", "including", "containing" do not exclude other elements or steps. It should be emphasized that the term "comprises / comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components. It does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. The term "and / or" is to be interpreted as meaning "both" as well and each as an alternative. More specifically, the wording "one or more" of a set of elements (as in "one or more of A, B and C" or "at least one of A, B and C") is to be interpreted as either a conjunctive or disjunctive logic. Put differently, it may refer either to all elements, one element or combination of two or more elements of a set of elements. For example, the wording "A, B and C" may be interpreted as A or B or C, A and B and C, A and B, B and C, or A and C.

[0036] It will also be understood that, although the term first, second, etc. may be used herein to describe various elements or features, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, an antenna could be termed a second antenna, and, similarly, a second antenna could be termed a first antenna, without departing from the scope of the embodiments. The first antenna and the second antenna are both antennas, but they are not the same antenna, unless stated otherwise.

[0037] Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the provided antenna structure, and base station comprising such an antenna structure, it will be apparent to one skilled in the art that the antenna structure and the base station may be realized without these details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present disclosure.

[0038] Figure 1 illustrates, by way of example, a dual-polarized antenna structure 100 (or "antenna structure" for short) in accordance with some embodiments. It is to be noted that the antenna structure 100 is shown upside-down, i.e. in a perspective view from below, in order to better show the active parts of the antenna structure 100. The antenna structure 100 herein refers to the components of an antenna 600 that is responsible for the transmission and reception of radio signals, and which defines the radiation characteristics of the antenna 600. The antenna structure 100 may, together with additional components, such as additional mechanical and electric parts, a power supply, an antenna interface, processing circuitry etc. make up an antenna system or base station. Such a base station 800 will be further explained below in connection with Fig. 8. However, for ease of reference, the wording "radio transceiver" (which may comprise a radio transmitter and / or radio receiver) is used to refer to the components (additional mechanical and electric parts, a power supply, an antenna interface, processing circuitry etc.) responsible for producing a driving signal, which can be transmitted to the antenna structure 100 for radio transmission, or for converting radio waves received by the antenna structure 100 to information on a useable form. A radio transceiver together with the antenna structure 100 may thus make up the necessary components for transmitting and receiving radio signals.

[0039] The antenna structure 100 (or rather the antenna comprising the antenna structure) should be seen as a unit for transmitting and / or receiving electromagnetic waves. More specifically, the antenna structure 100 may be configured to transmit and / or receive radio waves. Radio waves (also referred to as radio signal, or radio frequency (RF) signal) herein refers to electromagnetic waves in a certain frequency range (i.e. a radio frequency range).

[0040] In the broadest example embodiment, the antenna structure 100 comprises a first radiating unit 200 and a second radiating unit 300. The wording "radiating unit" is herein to be construed as a component responsible for converting electrical signals into electromagnetic waves (e.g. radio waves), or for receiving electromagnetic waves and converting them into electrical signals. Thus, it can be seen as the part of the antenna where the energy from the radio transmitter is transformed into the desired radiation pattern, or where the energy of a received radio wave is transformed into a useful signal by the radio receiver. In many antennas, the radiating unit is typically a conductive element or an array of antenna elements. The design of the radiating unit depends on the type of antenna and its intended application.

[0041] The first radiating unit 200 has a first polarization. In other words, the first radiating unit 200 is configured to transmit / receive electromagnetic waves with the first polarization. The second radiating unit 300 has a second polarization. The second polarization is orthogonal to the first polarization. Thereby, a dual-polarized antenna structure 100 which can both transmit and receive signals in two orthogonal polarizations can be achieved. In some embodiments, the polarization refers to a linear polarization of the transmitted / received waves. Thus, by the first and second polarization being orthogonal to each other, in reference to linear polarization, it is herein meant that an electric field vector of the first radiating unit 200 oscillates in a plane perpendicular to a plane of oscillation of an electric field vector of the second radiating unit 300.

[0042] In a typically arrangement, the first polarization may be a horizontal polarization, and the second polarization may be a vertical polarization. It is however to be appreciated that depending on the orientation of the antenna structure, the first and second polarization may be different from the horizontal and vertical direction (although still orthogonal to each other).

[0043] Looking first at the first radiating unit 200. The first radiating unit 200 is arranged on a first substrate 204. The first substrate 204 may be seen as a part of the first radiating unit 200. The term "substrate" refers to a non-conductive or dielectric substrate on which electrically conductive patterns such as electrically conductive tracks or feeding ports can be provided. A substrate may further comprise vias and pads, laminated on, under or between different layers of the substrate. It may further comprise electrical components such as amplifiers, switches and DC circuitry. The substrate may be a printed circuitry board (PCB). In the illustrated example, the first substrate 204 has a circular shape. Such a shape may be advantageous for achieving a space efficient omnidirectional radiating unit. The first substrate 204 may however have any arbitrary shape.

[0044] The first radiating unit 200 comprises a first feeding network 202 (see. Fig. 2A) and a tapered-slot antenna array 208. The tapered-slot antenna array 208 may also commonly be known as a flared-notch antenna array.

[0045] The antenna structure 100 is herein illustrated in a perspective view showing the first radiating unit 200 from a second side. As seen herein, the tapered-slot antenna array 208 is arranged on the second side 206b of the first substrate 204. The first feeding network 202 is arranged on a first side 206a of the first substrate 204. The second side 206b being an opposite side from the first side 206a. It goes without saying that the tapered-slot antenna array 208 may as well be provided on the first side 206a of the first substrate 204, while the first feeding network 202 is provided on the second side 206b of the first substrate 204.

[0046] The term "antenna array" or "array of antenna elements" herein refers to a set of two or more connected antenna elements which work together as a single radiating unit. This way, signals of the two or more antenna elements can be combined in order to achieve improved performance over that of a single antenna element. For instance, they are able to match a radiation pattern to a desired coverage area, changing radiation pattern, adapting to changing signal conditions and some configurations can cover a large bandwidth. Antenna arrays can be described by their radiation patterns and by the type of antenna elements in the system. In this disclosure the tapered-slot antenna array 208 comprises a plurality of tapered-slot elements 210a- 210d (see Fig. 2B). More specifically, the tapered-slot antenna array 208 comprises two or more tapered- slot elements. In some embodiments, the tapered-slot antenna array 208 comprises at least three tapered-slot elements. Having at least three tapered-slot elements may be beneficial to achieve an omnidirectional radiation pattern of the first radiating unit 200 as it may reduce pattern degradations in some regions in case of fewer tapered-slot elements. In the illustrated example of Fig. 1 (also shown in Fig. 2A), the tapered-slot antenna array comprises four tapered-slot elements 210a-210d.

[0047] A radiation pattern, in the context of antennas and electromagnetic waves, refers to the magnitude and polarization of the field radiated by the antenna (structure). In other words, for any antenna emitting electromagnetic waves, the radiation pattern may describe how the waves propagate in space. An omnidirectional pattern is then achieved by an antenna which radiates equal radio power in all directions perpendicular to a central axis of the antenna.

[0048] The plurality of tapered-slot elements 210a-d may be distributed in a circumferential direction of the tapered-slot antenna array 208. Thereby, an omnidirectional radiation pattern can be achieved. Put differently, the plurality of tapered-slot elements 210a-d may be distributed around a central axis of the first radiating unit 200. In some embodiments, the plurality tapered-slot elements 210a-d may be uniformly distributed in the circumferential direction. This may aid in design and construction of the first feeding network.

[0049] A common type of tapered-slot antenna array 208 is the Vivaldi antenna array. Thus, the tapered-slot antenna array 208 may be a Vivaldi antenna array. Conventionally, the Vivaldi antenna array typically have a radiating part starting with a slot-line which widens in one direction, forming a tapered notch. The Vivaldi antenna array is usually designed such that each Vivaldi element is fed through a separate feeding port. The tapered slot of the Vivaldi antenna may also be referred to as radiation slot. The radiation slot can be seen as a cavity within the antenna element that guides electromagnetic waves from the cavity to be emitted from the antenna element.

[0050] Fig. 2A and 2B shows an example of the first radiating unit 200 in which the tapered-slot antenna array 208 is realized as a Vivaldi antenna array 208. The tapered-slot elements are thus formed by Vivaldi elements. It is however to be appreciated that the disclosed technology may be realized using different types of tapered-slot arrays as well. More specifically, Fig. 2A shows a first side 206a of the first substrate 204 of the first radiating unit 200. Fig. 2B shows the first radiating unit 200 from the second side 206b of the first substrate 204 of the first radiating unit 200. Looking first at Fig. 2B, the first radiating unit 200 comprises a tapered-slot antenna array 208 having four tapered-slot elements 210a-d (e.g. Vivaldi elements) distributed in a circumferential direction of the tapered-slot antenna array 208 (e.g. a Vivaldi antenna array). The tapered-slot elements are herein referred to as a first to fourth tapered-slot element denoted 210a to 210d and indicated by the dotted line segments.

[0051] The tapered-slot antenna array 208 may be provided as one integral structure arranged on the first substrate 204. The term "integral" refers to a unitary or one-piece structure made of a single material and does not include structures formed by e.g. welding, soldering or gluing several pieces together. Thus, the term "integral structure" refers to that the structure is a monolithic structure. Accordingly, the term "integral" may be interchanged with the term "monolithic". The tapered-slot antenna array 208 may be formed by etching a conductive material layer on the first substrate 204 to form the integral structure. This may allow for a cheap and rapid assembly and manufacturing of the tapered-slot antenna array 208. It is however to be appreciated that the tapered-slot antenna array 208 may be formed by a plurality of individual components as well.

[0052] Each tapered-slot element of the plurality of tapered-slot elements 210a-d (see e.g. the first tapered- slot element 210a for reference) comprises a slot-line 226 formed between a first body 232a and an adjacent second body 232b. The slot-line 226 widens in a radial direction of the first radiating unit 200 to form the tapered (or radiation) slot 228 intermediate the first and second body 232a, 232b. The radial direction herein refers to a direction along a radius from a center of the first radiating unit 200. The radiation slot 228 thus forms a tapered slot, when seen in a direction opposite the radial direction. The first and second body 232a, 232b may thus be seen as the conductive elements on either side of the slotline 226 and the radiation slot 228. The radiation slot 228 may be continuously tapering (as shown in Fig. 2B) or be step-wise tapering (e.g. as shown in Fig. 7A). Moreover, the radiation-slot may be exponentially tapered (as show in Fig. 2B) or be linearly tapered (not show).

[0053] The first and second body of the tapered-slot element may be coupled to an antenna ground plane 234. The antenna ground plane 234 herein forms a common structure connected to the first and second body of each tapered-slot element 210a-210d.

[0054] As seen in Fig. 2B, the plurality of tapered-slot elements 210a-d may be arranged such that the first body 232a and the second body 232b of each adjacent tapered-slot element forms a common structure. Thereby, a more compact and easily manufactured structure can be achieved. The common structure provides a further design possibility of the tapered-slot antenna array. The common structure may for instance be designed in view of on one or more antenna characteristics, such as the desired radiation pattern, frequency range, and / or diameter of the first radiating unit 200. As a non-limiting example, the common structure may be provided with a notch 236 as indicated by the dashed lines in Fig. 2B. The shape and size of the notch 236 may be selected such as to achieve e.g. the desired radiation pattern or frequency range. It is to be appreciated that other designs of the common structure are possible as well.

[0055] Moreover, the slot-line 226 may extend inwards (in opposite the radial direction) into a cavity 214 (or resonant cavity 214) formed intermediate the antenna ground plane 234 and the first and second body 232a, 232b. The cavity 214 may have a circular shape, as in conventional Vivaldi elements. However, in some embodiments, and as illustrated in Fig. 2B, the cavity 214 has an arc shape. The arc shape may extend in the circumferential direction of the first radiating unit 200. By having an arc-shaped cavity 214 a more space-efficient tapered-slot element 210a-d can be achieved (compared e.g. to a circular shape), thus resulting in a more compact antenna structure 100. Moreover, the arc-shaped cavity may help in creating an additional resonance within the cavity, to further facilitate a compact design of the tapered- slot elements. Additionally, the arc-shape may improve impedance matching of the antenna structure. The arc-shape may further aid in isolation between the first and second radiating unit.

[0056] More specifically, the cavity 214 may be formed as a ring segment (as shown). The cavity 214 of the plurality of tapered-slot elements 210a-d may form ring segments of a common ring shape. In this way, an electrical connection between the antenna ground plane 234 and the first and second body 232a, 232b of each tapered-slot element 210a-d can be achieved in between the ring segments, thus removing the need for any additional connectors. Moreover, the ring segments may be further advantageous in wideband operation of the antenna.

[0057] In some embodiments, the cavities 214 of the plurality of tapered-slot elements 210a-d may form a common cavity. Thus, the cavities 214 may form a (closed) ring shape. This may provide for improved matching between the plurality of tapered-slot elements 210a-d. In such case, the tapered-slot elements (or more specifically the first and second body 232a, 232b thereof) may be connected to the antenna ground plane 234 through electrical connections crossing the ring-shaped cavity 214. It should be noted that other shapes of the cavity 214 may be possible as well, such as a butterfly shape, or a bend bone shape.

[0058] Now looking at Fig. 2A, the first feeding network 202 arranged on the first side 206a of the first substrate 204 is shown. The wording "feeding network" should, throughout the present disclosure, be understood as a conductor, and any other associated equipment, which connects the radio transceiver with the antenna array or its elements. In other words, the feeding network may be seen as the component(s) responsible for distributing the RF signals between the radio transceiver and the radiating elements of the antenna (e.g. the tapered-slot antenna array). During transmission, the radio transceiver can generate an alternating current of radio frequency (i.e. a driving signal). The driving signal may then be fed through the feeding network to the antenna array, which converts the alternating current of the driving signal to radio waves. In receiving mode, the incoming radio waves can excite alternating currents in the antenna array, and the feeding network can deliver this current to the radio transceiver, which processes the signal. The feeding network can ensure proper distribution of the signals to achieve the desired radiation characteristics. The design of the feeding network depends on the type of antenna (or radiating unit), its intended application, and the desired performance characteristics.

[0059] The first feeding network 202 may comprise a plurality of feeding ports 216a-216d (or feed points). The plurality of feeding ports 216a-d may be arranged on the first side 206a of the first substrate 204, as shown herein. The feeding ports herein refers to a point on a driven radiating unit to which the driving signal is fed. More specifically, the first feeding network 202 may comprise a plurality of feeding ports 216a-d in a one-to-one correspondence with the plurality of tapered-slot elements 210a-210d of the tapered-slot antenna array 208. The plurality of feeding ports 216a-d of the first feeding network 202 may be coupled to the plurality of tapered-slot elements 210a-d in a one-to-one correspondence. Thus, each tapered-slot element 210a-d may be coupled to a respective feeding port 216a-d. A tapered-slot element and a corresponding feeding port may be coupled through a capacitive coupling. Alternatively, the tapered-slot element and a corresponding feeding port may be coupled through a via in the first substrate.

[0060] The first feeding network 202 may further comprise additional conductive lines 220 arranged on the first side 206a of the first substrate 204. The conductive lines 220 may be arranged to electrically connect the plurality of feeding ports 216a-d to a feeding line (see e.g. element 614b, 614c in Fig. 7A). The feeding line may be comprised in the first feeding network 202 (although not arranged on the first substrate 204). The feeding line (may also be referred to as a transmission line) should be seen as electric wiring for delivering the driving signal from the radio transceiver to the radiating unit. The feeding line may for example be a coaxial cable, twin-lead, or ladder line. In the example shown in Fig. 1, parts of the feeding line may be provided on a further substrate 205 (or board 205). The further substrate 205 may be arranged in a vertical manner, as shown in Fig. 1. The feeding line may thus be provided on a surface of the further substrate 205. The plurality of feeding ports 216a-d may be coupled to the driving signal of the first feeding network 202. The plurality of tapered-slot elements 210a-d may be coupled to ground (e.g. through the antenna ground plane 234. In case of a coaxial feed (i.e. the feeding line being a coaxial cable), the feeding ports 216a-d may be coupled to an inner connector of the coaxial cable, and the plurality of tapered-slot elements 210a-d may be coupled to an outer connector of the coaxial cable. In the presently illustrated example, the conductive lines 220 connects the plurality of feeding ports 216a-d to a common point of the feeding line. As the plurality of tapered-slot elements 210a-d should work together as a tapered-slot antenna array 208, the conductive lines 220 may be designed such that the plurality of feeding ports 216a-d are fed in phase.

[0061] Moreover, the conductive lines 220 of the first feeding network 202 may be further designed to compensate for an off-centered feeding line. As will be further explained below, the second radiating unit 300 is arranged in a central portion of the first radiating unit 200. To compensate for this, the feeding line of the first feeding network may be off-centered relative the first radiating unit 200. In the illustrated example, the feeding line may be provided through a first opening 222 of the first substrate 204. The second radiating unit 300 may then be provided through a second opening 224 in the central portion 212 of the first radiating unit 200. The feeding network (or more specifically the conductive lines 220) may then be designed to compensate for the off-centered feeding line, to feed the feeding ports 216a-d in phase.

[0062] Moving on to Fig. 3A and 3B which illustrates, by way of example, a respective side of the second radiating unit 300 of the antenna structure as shown also in Fig. 1. More specifically, Fig. 3A shows the second radiating unit 300 from a first side 306a and Fig. 3B shows the second radiating unit from a second side 306b. In addition, an optional fourth radiating unit 300' is shown in a stacked manner with the second radiating unit 300. Together, the second and fourth radiating unit 300, 300' may form a vertically stacked radiating unit 301 having the second polarization. In other words, 301 denotes two radiating units having the second polarization and formed on a common substrate. Below, the second radiating unit 300 will be explained in further detail. It is however to be understood that the same principles apply also to the fourth radiating unit 300'.

[0063] The second radiating unit 300 is arranged on a second substrate 304. The second substrate 304 may be seen as a part of the second radiating unit 300. The second radiating unit 300 comprises a dipole antenna 308a. The dipole antenna 308a is arranged on the second substrate 304. In the illustrated example, the second radiating unit 300 comprises two dipole antennas (also referred to as the dipole antenna 308a and a further dipole antenna 308b). The two dipole antennas 308a, 308b may be coupled to a common second feeding network 302, as will be further explained below. Any principles or features described in connection with the dipole antenna 308a are applicable also to the further dipole antenna 308b, unless otherwise stated. Moreover, it is to be understood that in the general case, the second radiating unit 300 comprises one or more dipole antennas. A dipole antenna typically comprises two identical conductive elements, such as metal wires or rods, oriented in opposite directions. For transmission, the driving signal is applied, or for receiving, the output signal is taken, between the two elements.

[0064] The dipole antenna 308a, as shown herein, comprises a first dipole element 310a extending in a first direction, DI, and a second dipole element 310b extending in a second direction, D2, opposite to the first direction. The first and second direction may be parallel with a longitudinal axis of the second radiating unit 300 (e.g. the central axis C as shown herein). The first and second dipole element 310a, 310b are advantageously of equal length for achieving symmetry and balanced radiation patterns. Even further, the dipole antenna 308a may be a half-wave dipole antenna. This means that the length of each dipole element is about half of the wavelength of the signals that the second radiating unit 300 is configured to transmit / receive, or more specifically, half of the wavelength of the center frequency of the frequency band that the second radiating unit 300 is configured to transmit / receive.

[0065] The dipole elements (may also be referred to as dipole arms) are herein provided as electrically conductive elements arranged on the second substrate 304. The electrically conductive elements may be formed by etching of a metal layer on the second substrate 304. As illustrated herein, the first and second dipole element 310a, 310b may be arranged on opposite sides of the second substrate 304. This may simplify design and construction of the second feeding network 302 of the second radiating unit 300, in particular in a case of having a fourth radiating unit 300' also arranged on the second substrate 304 as illustrated herein, and further explained below. The fourth radiating unit 300' may then be coupled to the same second feeding network 302, so as to be fed with the same driving signal. The dipole elements of one side of the second substrate 304 may then be coupled to ground, while the dipole elements on the other side of the substrate 304 may be coupled to the driving signal. However, in some embodiments, the dipole elements may all be arranged on a same side of the second substrate 304. The second feeding network 302 may then be arranged on the other side of the second substrate 304 and be connected to the dipole elements e.g. by vias in the second substrate 304.

[0066] A respective width of the first and second dipole element 310a, 310b may be increasing in the respective first and second direction, DI, D2. In other words, the width at a distal end of the dipole elements 310a, 310b may be greater than a width at an opposite end of the dipole elements (i.e. the end at which the dipole elements connects to the second feeding network 302. This may provide for better wide-band impedance matching.

[0067] The second feeding network 302 of the second radiating unit 300 may be arranged on the second substrate 304. The first dipole element 310a may be coupled to a driving signal of the second feeding network 302 (or a microstrip line). The second dipole element 310b may then be coupled to ground. It is however to be appreciated that the opposite may be applicable as well. The principles mentioned above in connection with the first feeding network 202 may be applicable also to the second feeding network 302, unless otherwise stated. For example, the second feeding network 302 may be connected to, or comprise, a feeding line, such as a coaxial cable or any other suitable connector, for feeding the signals between the radio transceiver and the second radiating unit 300. Moreover, the second feeding network 302 may comprise additional conductive lines for connecting the dipole antenna 308a to the feeding line. The conductive lines connected to the first and second dipole element 310a, 310b may be formed as an integral part to the respective dipole element, e.g. by being etched from a common metal layer. Moreover, the conductive lines may advantageously be formed on the same side of the second substrate as the dipole elements they are to connect to.

[0068] It is to be appreciated that the herein illustrated structure of the first and second feeding network 202, 302 as illustrated in Fig. 2A to 3B are merely an example, and may be designed differently depending on a specific realization. It is to be further noted that the first and second radiating units may be connected to the same ground. Moreover, the first and second radiating units may be connected to the same driving signal.

[0069] As is further shown in Fig. 3A and 3B, the second radiating unit 300 may further comprise a further dipole antenna 308b. The further dipole antenna 308b comprises a third dipole element 310c and a fourth dipole element 310d. The third dipole element 310c may extend in the first direction, DI, and the fourth dipole element 310d may extend in the second direction, D2. Thus, the third dipole element 310c may be arranged in parallel with the first dipole element 310a, and the fourth dipole element 310d may be arranged in parallel with the second dipole element 310b.

[0070] More specifically, the third dipole element 310c may be electrically connected to the first dipole element 310a, and the fourth dipole element 310d may be electrically connected to the second dipole element 310b. Put differently, the first dipole element 310a may be connected to the same part of the second feeding network 302 as the third dipole element 310c, so as to be fed by the same signals. Similarly, the second dipole element 310b may be connected to the same part of the second feeding network 302 as the fourth dipole element 310d. Thereby, the dipole antenna 308a formed by the first and second dipole element 310a, 310b, and the further dipole antenna 308b formed by the third and fourth dipole element 310c, 310d may work together as to form a dual dipole antenna. Put differently, any dipole elements of the antenna structure 100 extending in the first direction should be connected to the same signal (either ground or the driving signal), and any dipole elements of the antenna structure 100 extending in the second direction should be connected to the same signal. In the dual dipole antenna set-up as shown herein, the two dipole antennas 308a, 308b may be offset from the central axis (herein denoted by C) of the second radiating unit 300 (or of the stacked radiating unit 301) by a same distance, on a respective side of the central axis, C. In other words, the further dipole antenna 308b (i.e. the third and fourth dipole element 310c, 310d) may be a mirrored structure of the dipole antenna 308a (i.e. the first and second dipole element 310a, 310b), as seen along the central axis C. Thereby, a phase center of the combined radiation pattern of the dual dipole antenna may be achieved around the central axis, C, of the second radiating unit 300.

[0071] In a single dipole antenna set-up (not shown), the dipole antenna 308a may be arranged along the central axis, C, to achieve a centered phase center. In other words, the offset from the central axis, C, may be zero.

[0072] Now turning back to Fig. 1, which shows, by way of example, how the first and second radiating units 200, 300 can be arranged in relation to each other. The second radiating unit 300 is arranged so as to extend through a central portion 212 of the first radiating unit 200, and such that the first and second dipole element 310a, 310b of the second radiating unit 300 are arranged at a respective side of the first substrate 204 of the first radiating unit 200. Put differently, the second radiating unit 300 may be arranged to extend through the central portion 212 of the first radiating unit 200 such that a phase center of the first radiating unit 200 coincides with a phase center of the second radiating unit 300. In other words, a common phase center between the first and second radiating unit 200, 300 may be achieved. It is however to be noted that due to e.g. manufacturing tolerances, or other inaccuracies, the phase center of the first and second radiating unit 200, 300 may not exactly coincide, but rather be within a defined error margin of each other.

[0073] In some embodiments, the second radiating unit 300 may be arranged through the first radiating unit 200 such that the dipole antenna 308a (and the optional further dipole antenna 308b) is structurally symmetric around the first radiating unit 200.

[0074] The first and second radiating units 200, 300 of the proposed antenna structure 100 can thus achieve similar radiation patterns, centered around the same point. This may provide for improvements e.g. in regards to signaling performance and usability of the antenna structure 100.

[0075] In order to better show how the second radiating unit 300 extends through the first radiating unit 200, the central portion 212 of the first radiating unit 200 is shown as hollow. It is however to be noted that the first substrate 204 of the first radiating unit 200 may extend so as to abut the second substrate 304 of the second radiating unit 300 (and the further substrate 205), as shown e.g. in Fig. 2A and 2B. Through this connection, the first and second substrate may be attached to each other. The same holds for the antenna structure 400 shown in Fig. 4A and 4B.

[0076] As has been explained in the foregoing, the antenna structure 100 in its broadest form comprises a pair of radiating units (i.e. the first and second radiating units 200, 300) of different polarizations (i.e. the first and second polarization). And the pair of radiating units being arranged such that they share a common phase center. However, in some embodiments, the antenna structure 100 may comprise more than one pair of radiating units, i.e. a plurality of pairs of radiating units. For ease of reference, the wording "pair of radiating units" or "radiating unit pairs" is used in the following to refer to one radiating unit having the first polarization and one radiating unit having the second polarization and arranged together, as explained above as part of the broadest form of the presently disclosed technology. The plurality of pairs of radiating units are matched so as to work together as two combined antennas of the two different polarities. By providing a plurality of pairs of radiating units, i.e. stacking several radiating unit pairs in accordance with the presently disclosed technology, a gain of the antenna can be increased. The antenna structure may further provide for space diversity, meaning radiating units of the two different polarizations can be placed in close vicinity (approximately between 0.5 to 1 times the wavelength in distance.

[0077] As an example of an antenna structure comprising more than one pair of radiating units, Fig. 1 shows an example where the antenna structure 100 further comprises a third radiating unit 200' having the first polarization, and a fourth radiating unit 300' having the second polarization. The use of the character ' is herein used to denote a further instance of a previously described component. For example, the third radiating unit denoted 200' is another instance of the first radiating unit denoted 200. Thus, any features or principles of the first radiating unit 200 applies also to the third radiating unit 200'.

[0078] In particular, the third radiating unit 200' comprises a third feeding network arranged on a first side of a third substrate, and a tapered-slot antenna array 208' arranged on a second side of the third substrate opposite to the first side. The tapered-slot array comprises a plurality of tapered-slot elements distributed in a circumferential direction of the tapered-slot antenna array. The third feeding network may be coupled to the first feeding network. Thereby, the first and third radiating unit may be fed by the same signal so as to work together as a common radiating unit having the first polarization. Moreover, the third feeding network may share some components with the first feeding network, such as the feeding cable. However, the third radiating unit is provided with a separate plurality of feeding ports for feeding the tapered-slot elements of the third radiating unit, as shown herein. Similarly, the fourth radiating unit 300' should be understood as another instance of the second radiating unit 300 as shown e.g. in Fig. 3A and 3B. Thus, the above described principles of the second radiating unit are applicable also to the fourth radiating unit. In particular, the fourth radiating unit 300' comprises a dipole antenna 308a' arranged on a fourth substrate. It may further comprise a further dipole antenna 308b' as illustrated herein. The dipole antenna comprises a first dipole element extending in the first direction and a second dipole element extending in the second direction, opposite the first direction. The fourth radiating unit may further comprise a fourth feeding network, which may be coupled to the second feeding network. Thereby, the second and fourth radiating unit may be fed by the same signal so as to work together as a common radiating unit having the second polarization. Moreover, the fourth feeding network may share some components with the second feeding network, such as the feeding cable.

[0079] As with the first and second radiating unit 200, 300, the fourth radiating unit 300' may be arranged such that it extends through a central portion of the third radiating unit 200', such that the first and second dipole element of the fourth radiating unit 300' are arranged at a respective side of the third substrate of the third radiating unit 200'.

[0080] In the illustrated example, the first pair of radiating units 102 (i.e. the first and second radiating unit 200, 300) and the second pair of radiating units 104 (i.e. the third and fourth radiating unit 200', 300') arranged in a vertically stacked arrangement. In such case, the second substrate of the second radiating unit 300 and the fourth substrate of the fourth radiating unit 300' may be formed by a common substrate.

[0081] In another example, e.g. looking at the upper (or lower) half of the antenna structure 400 in Fig. 4A and 4B, or as shown in Fig. 6, the first pair and the second pair may be arranged in a side-by-side arrangement. In such case, the first substrate of the first radiating unit 200 and the third substrate of the third radiating unit 200' may be formed by a common substrate. The second substrate of the second radiating unit 300 and the fourth substrate of the fourth radiating unit 300' may be formed on two separate structures (as shown in Fig. 4A and 4B), or on a common structure (as shown in Fig. 6).

[0082] In either case (i.e. vertically stacked or side-by-side arrangement), the use of a common substrate may be advantageous in that is can help in ensuring that the two radiating units arranged on the common substrate are formed in a common plane, such that there is no spatial offset between their main plane of extension.

[0083] Figure 4A and 4B illustrates, by way of another example, an antenna structure 400 in accordance with some embodiments. The antenna structure 400 is shown in perspective view from a bottom side of the antenna structure 400 (i.e. upside-down), in order to better show the active parts of the antenna structure 400. Fig. 4A and 4B shows the antenna structure 400 from two different sides.

[0084] The antenna structure comprises a first through fourth pair of radiating units 402a-d arranged in a stacked manner. Any features or aspects of the antenna structure 100 as described above in connection with Fig. 1 to 3B are applicable to the antenna structure 400 as described in connection with Fig. 4A to 5B, and vice versa. In particular, the antenna structure 400 can be seen as two instances of a vertically stacked pair of radiating units (as shown in Fig. 1), arranged side-by-side. Alternatively, the antenna structure 400 can be seen as two instances of a side-by-side arrangement of the pair of radiating units (as mentioned above), arranged on top of each other. Even though not clearly shown, the side-by-side stacked radiating unit 501, 501' having the first polarization may be arranged along the vertically stacked radiating unit 301, 301' having the second polarization at a position such that the respective dipole elements (as explained above) are arranged at a respective side of the side-by-side stacked radiating unit 501, 501'. This can e.g. be seen in Fig. 4A, which shows dipole elements of the vertically stacked radiating units 301, 301' extending in a downwards direction (cf. second direction as described above) below the respective side-by-side stacked radiating unit 501, 501'. Then in Fig. 4B, the oppositely directed dipole elements of the vertically stacked radiating units 301, 301' extends in an upwards direction (cf. first direction as described above) above the respective side-by-side stacked radiating unit 501, 501'.

[0085] In present example of Fig. 4A and 4B, the antenna structure 400 is formed by a 2-by-2 arrangement of the first through fourth radiating unit pairs 402a-d. The first number herein denotes the number of pairs in side-by-side arrangement, and the second number denotes the number of pairs stacked on top of each other. For comparison, the antenna structure 100 shown in Fig. 1 can be seen as a l-by-2 arrangement. The antenna structure according to the presently disclosed technology can be realized in any suitable arrangement. For example, the antenna structure 100 of Fig. 1 may alternatively be arranged in a 2-by-l arrangement. As a further example, the antenna structure 400 as shown in Fig. 4A and 4B may alternatively be arranged in a l-by-4 or a 4-by-l arrangement. Moreover, the antenna structure can be realized by any number of radiating unit pairs. For example, the antenna structure 100 of Fig. 1 can be expanded along any dimension to form e.g. an arrangement of l-by-3, a 3-by-l, l-by-4, 4-by-l etc. In another example, the antenna structure 400 of Fig. 4A and 4B may be expanded to form e.g. an arrangement of 2-by-3, 3-by-2, 2-by-4, 4-by-2, etc. In the above examples, the antenna structure is formed in two dimensions, i.e. stacked side-by-side and / or top-to-bottom. The antenna structure may however be expanded in a third dimension as well, i.e. stacked front-to-back. As an example, by providing two instances of the antenna structure shown in Fig. 4A and 4B in a front-to- back arrangement, a 2-by-2-by-2 arrangement can be achieved. Fig. 4A further shows feed lines 404 (herein illustrated as a coaxial cable) coupled to the feeding network of the two vertically stacked radiating unit 301 having the second polarization. When arranged in a complete antenna, the antenna structure 400 may be arranged such that the ends of the vertically stacked radiating unit 301 having the feeding lines 404 are arranged towards a base of the antenna.

[0086] Moreover, the antenna structure 400 may further comprise a further substrate 405 (or board 405). The further substrate 405 may be arranged in a vertical manner. At least parts of the feeding network for the respective side-by-side stacked radiating unit 501, 501' may be provided on the further substrate 405. The grounds of the side-by-side stacked radiating units 501, 501' and the respective vertically stacked radiating units 301, 301' may be connected to the same ground to avoid any resonance effects. The further substrate 405 may further serve the purpose of mechanically holding the side-by-side stacked radiating units 501, 501' in place. In other words, the side-by-side stacked radiating units 501, 501' (or rather substrate thereof) may be attached to the further substrate 405. Alternatively, or in combination, the side-by-side stacked radiating units 501, 501' (or rather substrate thereof) may be attached to the substrates of the respective vertically stacked radiating units 301, 301'. The same holds also for the other examples of antenna structures described herein.

[0087] Figure 5A and 5B illustrates, by way of example, a respective side of the side-by-side stacked radiating unit 501, 501' having the first polarization. In other words, two radiating units having the first polarization and arranged on a common substrate. As the two radiating units 500, 500' (indicated by the two dotted line segments) may share features and principles of the radiating units having the first polarization as described above, focus will be made on any new and additional features, in order to avoid undue repetition.

[0088] As seen in Fig. 5A, the tapered-slot antenna arrays 508, 508' of the two radiating units 500, 500' may be electrically connected to each other. This may e.g. be realized by having the tapered-slot antenna arrays 508, 508' formed by an integral structure. This may enable the two neighboring radiating units to be positioned even closer to each other to reduce the overall footprint of the antenna structure. Moreover, it may improve the omnidirectional radiating pattern of the antenna structure, as compared to having them separated. However, in some embodiments, the two tapered-slot antenna arrays 508, 508' may be two separate conductive elements.

[0089] Fig. 5B illustrates parts of the feeding networks 502, 502' for the respective radiating unit 500, 500'. Each feeding network comprises a plurality of feeding ports 516a-c in a one-to-one correspondence with the plurality of tapered-slot elements 510a-d of the respective radiating unit 500, 500'. In the present example, the feeding networks 502, 502' of the two neighbouring radiating units 500, 500' are provided as two separate networks on the common substrate 504. Although, in some embodiments, they may be implemented as one common feeding network. Additionally, even though separated on the common substrate 504, the feeding networks 502, 502' may be coupled to a common feeding line.

[0090] Moreover, looking e.g. at the left radiating unit denoted by 500, is it shown that the plurality of feeding ports 516a-d may be connected in pairs to the feeding line (as opposed to in Fig. 2A). In general, the plurality of feeding ports 516a-d may be connected through conductive lines 520 to the feeding line in any suitable way, depending on a specific realization. The examples shown herein are thus not to be seen as limiting examples.

[0091] As in the case of the substrate shown e.g. in Fig. 2A and 2B, the common substrate 504 shown herein may be of any arbitrary shape.

[0092] Figure 6 illustrates, by way of example, an antenna 600 in accordance with some embodiments. The antenna 600 may be a dual-polarized omnidirectional antenna. The antenna 600 may be part of a base station, such as the base station 800 described below in connection with Fig. 8.

[0093] The antenna 600 comprises an antenna structure 602. The antenna structure may be any antenna structure as described above. For example, the antenna structure 100 described in connection with Fig. 1, or the antenna structure 400 described in connection with Fig. 4A and 4B. However, in the illustrated example, the antenna structure 602 comprises a first and a second pair 616a, 616b of radiating units, in a side-by-side arrangement. A side-by-side stacked radiating unit 606 having the first polarization is thus provided on a common substrate. The side-by-side stacked radiating unit 606 comprise two radiating units having the first polarization (cf. first and third radiating unit 200, 200' in Fig. 1). The side-by-side stacked radiating unit 606 is further illustrated in Fig. 7A and 7B.

[0094] The first pair 616a of radiating units comprises a radiating unit having the second polarization (cf. second radiating unit 300 in Fig. 1), which comprises a dipole antenna. The dipole antenna of the first pair 616a of radiating units comprises a first dipole element 608a, and a second dipole element (not shown). The second dipole element is not visible as it is provided on the other side of the antenna structure 602. Moreover, parts of a feeding network 618a for supplying said dipole antenna is also shown. The second pair 616b of radiating units also comprises a radiating unit having the second polarization (cf. fourth radiating unit 300' in Fig. 1), which comprises a dipole antenna comprising a first and second dipole element (not shown). Moreover, parts of a feeding network 618b for supplying said dipole antenna is shown. The two radiating units having the second polarization are herein provided on a common structure 610, as an alternative to separate structures as shown e.g. in Fig. 4A and 4B. Fig. 6 further illustrates a first through fourth feeding line 614a-d of the antenna 600 (herein illustrated as coaxial cables). In the illustrated example, the first feeding line 614a feeds the radiating unit having the second polarization of the first pair 616a of radiating units. The second feeding line 614b feeds the radiating unit having the first polarization of the first pair 616a of radiating units. The third feeding line 614c feeds the radiating unit having the first polarization of the second pair 616b of radiating units.

[0095] The fourth feeding line 614d feeds the radiating unit having the second polarization of the second pair 616b of radiating units.

[0096] The antenna 600 further comprises a radome 605. The antenna 600 further comprises a base 612 to which components may be mounted, such as the antenna structure 602 and the radome 605.

[0097] Figure 7A and 7B illustrates a respective side of the side-by-side stacked radiating unit 606 having the first polarization. In other words, two radiating units having the first polarization and arranged on a common substrate. The two radiating units comprises a respective tapered-slot antenna array 608, 608', as has been further explained above.

[0098] In addition to what has been previously shown, the tapered-slot antenna array 608, 608' is herein shown as having a step-wise tapered slot. Alternatively, the respective first and second body forming the radiation slot may be seen as having a respective notch.

[0099] Fig. 7A and 7B further shows the second and third feeding line 614b, 614c being connected to the stacked radiating unit 606. As shown herein, the outer conductor of the feeding lines 614b, 614c may be coupled to the tapered-slot antenna array 608, 608'. The inner conductor of the feeding lines 614b, 614c may be coupled to the respective feeding network 602, 602'. As is further shown, the feeding lines 614b, 614c may be off-centered in relation to the respective tapered-slot antenna array 608, 608' to allow for an opening 622, 622' in a central portion. Through the openings 622, 622', the respective radiating unit having the second polarization can be arranged.

[0100] As is further shown, the common substrate 604 may be provided with one or more mounting holes 636 for mounting the side-by-side stacked radiating unit 606 in the antenna 600. By using a common substrate 604, construction of the antenna structure can thereby be simplified.

[0101] Fig. 8 is a schematic illustration of a base station 800 in accordance with some embodiments. The base station 800 may for instance be used in mobile communication networks, or in testing scenarios. As used herein, base station 800 refers to a device or unit capable, configured, arranged and / or operable to transmit and / or receive signals using electromagnetic waves, such as radio waves. In particular, the base station 800 may communicate over wide- or ultrawide-band, by which it is meant a wide range of frequencies, including, but not limited to 4G, 5G, 6G, and millimeter wave (mmWave) bands. As an example, the antenna structure of the base station 800 can be designed to work in the range of 5 to 9 GHz (e.g., 5.9 to 8.4 GHz), and / or in the range of 10-16 GHz (e.g., 10.7 to 15.35 GHz). However, also lower frequencies are possible.

[0102] The base station 800 may communicate with other base stations, or any type of mobile communication enabled device, such as a smart phone, a mobile phone, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a vehicle etc.

[0103] The base station 800 may comprise processing circuitry 808 (may also be referred to as control circuitry 808) and a memory 810. The processing circuitry 808 may be configured to perform the overall functions and operations of the base station 800. The processing circuitry 808 may be distributed over several circuitry devices. The processing circuitry 808 may comprise one or more processors, such as a central processing unit (CPU), microcontroller, or microprocessor. The one or more processors may be configured to execute program code stored in the memory 810, in order to carry out various functions and operations of the base station 800. The processor(s) may be or include any number of hardware components for conducting data or signal processing or for executing computer code stored in the memory 810. The memory 810 optionally includes high-speed random-access memory, such as DRAM, SRAM, DDR RAM, or other random-access solid-state memory devices; and optionally includes nonvolatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory 810 may include database components, object code components, script components, or any other type of information structure for supporting the various activities of the present disclosure. Furthermore, the processing circuitry 808 may include baseband processing circuitry and application processing circuitry.

[0104] As illustrated in Fig. 8, the base station 800 comprises an antenna such as the antenna 600 as described above in connection with Fig. 6. The antenna 600 may be connected to an interface 802 of the base station 800. The interface 802 may comprise RF front-end circuitry 804 and the antenna 600. The RF front-end circuitry 804 may comprises one or more filters, one or more amplifiers (e.g. VGAs and LGAs), one or more mixers, one or more ADCs, one or more PLLs, and one or more DACs. The RF front-end circuitry 804 is connected to the antenna 600 and processing circuitry 808, and is configured to condition signals communicated between antenna 600 and processing circuitry 808. The RF front-end circuitry 804 may be coupled to or a part of the antenna 600. In some embodiments, the base station may not include separate RF front-end circuitry 804, rather, the processing circuitry 812 may comprise RF front-end circuitry and may be connected to antenna 600.

[0105] Similarly, in some embodiments, some or all of RF transceiver circuitry may be considered a part of the RF front-end circuitry 804. Moreover, the RF front-end circuitry 804 may receive digital data that is to be transmitted by the antenna 600. The RF front-end circuitry 804 may convert the digital data into a radio signal (or driving signal) having the appropriate channel and bandwidth parameters using a combination of components of the RF front-end circuitry 804. The radio signal may then be transmitted via the antenna 600. Similarly, when receiving data, the antenna 600 may collect radio signals which are then converted into digital data by the RF front-end circuitry 804. The digital data may be passed to processing circuitry 808. In other embodiments, the interface 802 may comprise different components and / or different combinations of components.

[0106] The power source 812 may, in some embodiments, be in the form of a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic devices or power cells, may also be used. The base station 800 may further comprise power circuitry 806 for delivering power from power source 812 to the various parts of the base station 800 which need power from power source 812 to carry out any functionality described or indicated herein. Power circuitry 806 may in certain embodiments comprise power management circuitry. Power circuitry 806 may additionally or alternatively be operable to receive power from an external power source, in which case the base station 800 may be connectable to the external power source (such as an electricity outlet) via input circuitry or an interface such as an electrical power cable. The power circuitry 806 may also in certain embodiments be operable to deliver power from an external power source to the power source 812. This may be, for example, for the charging of the power source 812. The power circuitry 806 may perform any formatting, converting, or other modification to the power from the power source 812 to make the power suitable for the respective components of the base station 800 to which power is supplied.

[0107] In the drawings and specification, there have been disclosed exemplary aspects of the disclosure. However, many variations and modifications can be made to these aspects without substantially departing from the principles of the present disclosure. Thus, the disclosure should be regarded as illustrative rather than restrictive, and not as being limited to the particular aspects discussed above. Accordingly, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0108] Exemplary embodiments of an antenna structure comprising a first and second tapered slot antenna array (may also be referred to as side-by-side stacked radiating unit) are set out in the following items. Some embodiments of said antenna structure are shown in Fig. 5A and 5B, as well as in Fig. 7A and 7B.

[0109] Item 1. An antenna structure comprising: a first tapered slot antenna array comprising a first plurality of tapered-slot elements distributed in a circumferential direction of the first tapered-slot antenna array; a second tapered slot antenna array comprising a second plurality of tapered-slot elements distributed in a circumferential direction of the second tapered-slot antenna array; wherein the first tapered slot antenna array and the second tapered slot antenna array are arranged on a first side of a common substrate in a side-by-side arrangement.

[0110] Item 2. The antenna structure according to item 1, wherein the first tapered slot antenna array and the second tapered slot antenna array are electrically coupled to each other.

[0111] Item 3. The antenna structure according to item 1 or 2, wherein a distance between the first and second tapered slot antenna array is less than, or equal to a wavelength of a radio signal which the antenna structure is configured to transmit. Put differently, a phase centre of the first tapered slot antenna array may be within a distance of a phase centre of the second tapered slot antenna array corresponding to the wavelength. In other words, the first and second tapered-slot antenna array may be spaced apart by less than the wavelength. In some embodiments, they may be spaced apart by at least one half of the wavelength.

[0112] Item 4. The antenna structure according to any one of the items 1 to 3, wherein the first tapered slot antenna array and the second tapered slot antenna array are formed by an integral structure.

[0113] Item 5. The antenna structure according to any one of the items 1 to 4, wherein the first tapered slot antenna array constitutes a first radiating unit, and the second tapered slot antenna array constitutes a second radiating unit.

[0114] Item 6. The antenna structure according to any one of the items 1 to 5, wherein a resonant cavity of each tapered-slot element of the first and second plurality of tapered-slot elements has an arc shape.

[0115] Item 7. The antenna structure according to any one of the items 1 to 6, wherein the first tapered-slot antenna array and the second tapered-slot antenna array are Vivaldi antenna arrays, and the tapered-slot elements of the first and second plurality of tapered-slot elements are Vivaldi elements.

[0116] Item 8. The antenna structure according to any one of the items 1 to 7, wherein the antenna structure further comprises first feeding network and a second feeding network arranged on a second side of the common substrate, opposite the first side; wherein the first and second feeding network comprises a respective a plurality of feeding ports in one-to-one correspondence with the respective first and second plurality of tapered-slot elements; and wherein the feeding ports of the respective plurality of feeding ports are coupled to the respective plurality of tapered-slot elements in a one-to-one correspondence.

[0117] Item 9. The antenna structure according to any one of the items 1 to 8, wherein the first and second plurality tapered-slot elements are uniformly distributed in the respective circumferential direction.

Claims

CLAIMS1. A dual-polarized antenna structure (100, 400) comprising a first radiating unit (200) having a first polarization and a second radiating unit (300) having a second polarization, wherein the first polarization is orthogonal to the second polarization, wherein the first radiating unit (200) comprises a first feeding network (202) arranged on a first side (206a) of a first substrate (204), and a tapered-slot antenna array (208) arranged on a second side (206b) of the first substrate (204) opposite to the first side (206a), wherein the tapered-slot antenna array (208) comprises a plurality of tapered-slot elements (210a-d) distributed in a circumferential direction of the tapered-slot antenna array (208); wherein the second radiating unit (300) comprises a dipole antenna (308a) arranged on a second substrate (304), wherein the dipole antenna (308a) comprises a first dipole element (310a) extending in a first direction and a second dipole element (310b) extending in a second direction opposite to the first direction; and wherein the second radiating unit (300) is arranged to extend through a central portion (212) of the first radiating unit (200), such that the first and second dipole element (310a, 310b) of the second radiating unit (300) are arranged at a respective side of the first substrate (204) of the first radiating unit (200).

2. The dual-polarized antenna structure (100, 400) according to claim 1, wherein a feeding line of the first feeding network 202 is off-centered relative the first radiating unit (200).

3. The dual-polarized antenna structure (100, 400) according to claim 1 or 2, wherein a resonant cavity (214) of each tapered-slot element of the plurality of tapered-slot elements (210a-d) has an arc shape.

4. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 3, wherein the first feeding network (202) comprises a plurality of feeding ports (216a-d) in one-to-one correspondence with the plurality of tapered-slot elements (210a-d); and the plurality of feeding ports (216a-d) of the first feeding network (202) are coupled to the plurality of tapered-slot elements (210a- d) in a one-to-one correspondence.

5. The dual-polarized antenna structure (100, 400) according to claim 4, wherein the plurality of feeding ports (216a-d) are coupled to a first driving signal of the first feeding network (202), and the plurality of tapered-slot elements (210a-d) are coupled to ground.

6. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 5, wherein the dipole antenna (308a) is a half-wave dipole antenna.

7. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 6, wherein the second radiating unit (300) further comprises a further dipole antenna (308b), the further dipole antenna (308b) comprising a third dipole element (310c) extending in the first direction and a fourth dipole element (310d) extending in the second direction, wherein the third dipole element (310c) is electrically connected to the first dipole element (310a), and the fourth dipole element (310d) is electrically connected to the second dipole element (310b).

8. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 7, wherein a respective width of the first and second dipole element (310a, 310b) is increasing in the respective first and second direction.

9. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 8, wherein the second radiating unit (300) comprises a second feeding network (302) arranged on the second substrate (304), and wherein the first dipole element (310a) is coupled to a driving signal of the second feeding network (302), and the second dipole element (310b) is coupled to ground.

10. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 9, wherein the plurality tapered-slot elements (210a-d) are uniformly distributed in the circumferential direction.

11. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 10, wherein the tapered-slot antenna array (208) is a Vivaldi antenna array, and the tapered-slot elements (210a-d) are Vivaldi elements.

12. The dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 11, wherein the antenna structure further comprises: a third radiating unit (200') having the first polarization, the third radiating unit comprising a third feeding network arranged on a first side of a third substrate, and a tapered- slot antenna array arranged on a second side of the third substrate opposite to the first side,wherein the tapered-slot array comprises a plurality of tapered-slot elements distributed in a circumferential direction of the tapered-slot antenna array; and a fourth radiating unit (300') having the second polarization, said fourth radiating unit comprising a dipole antenna arranged on a fourth substrate, wherein the dipole antenna comprises a first dipole element extending in the first direction and a second dipole element extending in the second direction opposite to the first direction, wherein the fourth radiating unit is arranged such that it extends through a central portion of the third radiating unit, such that the first and second dipole element of the fourth radiating unit are arranged at a respective side of the third substrate of the third radiating unit.

13. The dual-polarized antenna structure (100, 400) according to claim 12, wherein the first substrate and the third substrate is formed by a common substrate.

14. The dual-polarized antenna structure (100, 400) according to claim 12, wherein the second substrate and the fourth substrate is formed by a common substrate.

15. An antenna (600) comprising: a dual-polarized antenna structure (602) according to any one of the claims 1 to 14, and a plurality of feeding lines (614a-d) coupled to the antenna structure (602), and configured to feed the antenna structure (602) with a driving signal.

16. A base station (800) comprising the dual-polarized antenna structure (100, 400) according to any one of the claims 1 to 14.

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