A dipole antenna arrangement and array antenna

Abstract

The present disclosure relates to a dipole antenna arrangement (300) comprising a first dipole arm (301) and a second dipole arm (302) which form a first dipole antenna element (301, 302) that runs along a first antenna extension (E1) and runs parallel to a first plane (P1) The dipole antenna arrangement (300) further comprises a first balun feeding arrangement (205, 305) that is adapted to feed the first dipole antenna element (301, 302) and is formed on opposite main sides (335, 336) of a first feed printed circuit board, PCB, (310) that runs in a second plane (P2) that is separate from the first plane (P1). The first feed PCB (310) comprises at least one electrically conductive loop element (313a, 313b; 314a, 314b) for each one of the first dipole arm (301) and the second dipole arm (302). Each loop element (313a, 313b; 314a, 314b) comprises a respective loop conductor arranged on one of the main sides (335, 336) of the first feed PCB (310) such that it is adapted to be capacitively coupled to a respective dipole arm (301, 302) of the first feed PCB (310).

Description

[0001] TITLE

[0002] A dipole antenna arrangement and array antenna

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to a dipole antenna arrangement that comprises a first dipole arm and a second dipole arm that run parallel to a first plane. The dipole antenna arrangement further comprises a first balun feeding arrangement that is adapted to feed the dipole arms and is formed on opposite main sides of a first feed printed circuit board (PCB) that runs in a second plane that is separate from the first plane.

[0005] The present disclosure relates to array antennas comprising dipole antenna arrangements.

[0006] BACKGROUND

[0007] Growing demands on efficient communication require efficient array antennas and thus more advanced antenna elements, for example in AAS (Advanced Antenna Systems) where for example analog beamforming, digital beamforming and hybrid beamforming may be employed. In particular, several frequency bands are to be covered while maintaining a compact design.

[0008] Having antenna elements with relatively small dimensions requires more space between neighboring antenna elements in both rows and columns in a two-dimensional array antenna, which is an advantage for the coupling issues in those limited-small spacings. However, the smaller antenna elements, the higher the frequency band of operation becomes.

[0009] One suitable type of antenna element is a balun-fed dipole antenna element, these are commonly known from the literature and various design examples exist. Feeding a dipole antenna element properly via baluns requires considering a desired maximum balun height and its footprint dimensions due to system requirements within the desired bandwidth.

[0010] CN113131198A discloses an antenna design that aims at several frequency bands and compact size. There is a feeding point on a printed circuit board (PCB) top side connected to a balun, and the feeding point is in turn connected to a coupling filter structure on a PCB bottom side, and they together form a first lumped LC circuit. The first lumped LC circuit is coupled to, and electrically connected to, a second lumped LC circuit on the PCB top side, where the two lumped LC circuits form a dipole arm that thus is formed on both sides of the PCB.

[0011] It is desired to provide a dipole antenna arrangement that is relatively small while being adapted to operate in a relatively broad frequency band, in particular in several adjacent and / or separate frequency bands. The dipole antenna arrangement should be physically smaller with maintained desired frequency characteristics than has been accomplished previously, and should be suitable for use in an array antenna. It is also desired to provide array antennas that comprise such dipole antenna arrangements. SUMMARY

[0012] It is an object of the present disclosure to provide a dipole antenna arrangement that can be relatively physically small with maintained desired frequency characteristics, and enabling it to operate in a relatively broad frequency band, and to provide corresponding linear array antennas as well as corresponding two-dimensional array antennas which can be kept relatively physically small.

[0013] This object is obtained by means of a dipole antenna arrangement comprising a first dipole arm and a second dipole arm which form a first dipole antenna element that runs along a first antenna extension and runs parallel to a first plane. The dipole antenna arrangement further comprises a first balun feeding arrangement adapted to feed the first dipole antenna element and is formed on opposite main sides of a first feed printed circuit board (PCB) that runs in a second plane that is separate from the first plane. The first feed PCB comprises at least one electrically conductive loop element for each one of the first dipole arm and the second dipole arm. Each loop element comprises a respective loop conductor arranged on one of the main sides of the first feed PCB such that it is adapted to be capacitively coupled to a respective dipole arm of the first feed PCB.

[0014] This results in an increased electrical length of the dipole arms without increasing their physical sizes which is beneficial due to limited space. For example, this enables a small physical separation with respect to dipole arms of adjacent dipole elements in an array antenna. This also enables the dipole antenna arrangement to operate in a relatively broad frequency band, having an increased frequency band of operation.

[0015] According to some aspects, the first balun feeding arrangement comprises a first coupled transmission line pair, a second coupled transmission line pair, a first unbalanced port connector and a first balanced port. The coupled transmission line pairs are formed on opposite main sides of the first feed PCB, and the first balanced port comprises a first port connector and a second port connector. The first port connector is connected to the first dipole arm via a first arm connection, and the second port connector is connected to the second dipole arm via a second arm connection.

[0016] This means that many common and well-known types of balun feeding arrangements can be used in the dipole antenna arrangement

[0017] According to some aspects, the dipole antenna arrangement further comprises a third dipole arm and a fourth dipole arm which form a second dipole antenna element that runs along a second antenna extension and runs parallel to the first plane. The dipole antenna arrangement further comprises a second balun feeding arrangement that is adapted to feed the second dipole antenna element and is formed on opposite main sides of a second feed PCB that runs in a third plane that is separate from the first plane and the second plane. The second feed PCB comprises at least one electrically conductive loop element for each one of the third dipole arm and the fourth dipole arm, wherein each loop element comprises a respective loop conductor arranged on one of the main sides of the second feed PCB such that it is adapted to be capacitively coupled to a respective dipole arm of the second feed PCB. Having a first dipole antenna element and a second dipole antenna element enables the dipole antenna arrangement to be adapted for two different polarizations.

[0018] According to some aspects, the second balun feeding arrangement comprises a third coupled transmission line pair, a fourth coupled transmission line pair, a second unbalanced port connector and a second balanced port, where the coupled transmission line pairs are formed on opposite main sides of the second feed PCB. The second balanced port comprises a third port connector and a fourth port connector, where the third port connector is connected to the third dipole arm via a third arm connection and the where the fourth port connector is connected to the fourth dipole arm via a fourth arm connection.

[0019] This again means that many common and well-known types of balun feeding arrangements can be used in the dipole antenna arrangement. The two balun feeding arrangements need not be of the same type, but can be of mutually different designs if desired.

[0020] According to some aspects, the first plane, the second plane and the third plane are mutually perpendicular, and the second antenna extension runs along the third plane and is perpendicular to the first antenna extension. This enables an uncomplicated, easily assembled and stable configuration of the dipole antenna arrangement, being relatively inexpensive. This also means that the first dipole antenna element and the second dipole antenna element are adapted for mutually orthogonal polarizations.

[0021] According to some aspects, there are loop elements formed on opposite main sides of each feed PCB, such that pairs of opposing loop elements are formed, where each pair of opposing loop elements is positioned opposite a respective dipole arm. Having loop elements formed on opposite main sides of the feed PCB results in that they couple to the respective dipole arm from both sides of the feed PCB symmetrically, making the design more compact and enabling the radiation pattern to become more symmetrical with respect to boresight.

[0022] According to some aspects, each feed PCB comprises a set of loop elements, where at least one loop element in a set of loop elements comprises a loop conductor that runs in a closed loop. A closed loop geometry reduces the possibility of having undesired resonance / peak issues for the antenna return loss within the frequency band of operation.

[0023] Should there occur undesired return loss peaks, these may be shifted to occur outside of the frequency band of operation by careful design of a gap formed in the loop element possibly together with a corresponding increase of the total loop element conductor length. Therefore, according to some aspects, each feed PCB comprises a set of loop elements, where at least one loop element in a set of loop elements comprises a loop conductor that runs in an open loop, where the loop is open is open by means of a corresponding gap. According to some aspects, at least one loop element comprises a loop conductor that runs in a C-shape. Such a folded geometry enables the loop conductor to have sufficient length.

[0024] According to some aspects, the loop conductor of at least one loop element has an electrical length of a quarter wavelength, or an odd-numbered multiple of a quarter wavelength, of a frequency in a frequency band of operation, preferably a frequency in the lower half of the frequency band of operation, and more preferably a frequency in the lower quarter of the frequency band of operation.

[0025] This means that the loop element structure can be adapted for an extended frequency band of operation by adapting the loop length with a correct fraction in terms of with odd-numbered multiples the quarter wavelength at the frequency band of operation and considering the loop conductor width by taking into account the dielectric properties of the feed PCBs.

[0026] According to some aspects, at least one loop element is positioned to be most adjacent to a part of the corresponding dipole arm that is farthest away from an intersection between the second plane and the third plane.

[0027] By placing the loop elements on outer corners of the feed PCBs and positioning them under the dipole arms with a small optimum gap to the corresponding dipole arms the coupling between the loop elements and the corresponding dipole arms will be increased.

[0028] Regarding the details of the balun feeding arrangements, according to some aspects

[0029] - for each feed PCB, each coupled transmission line pair comprises overlapping parts of two conductor parts, where one conductor part is formed on a first main side of the feed PCB, and the other conductor part is formed on a second main side of the feed PCB, the main sides forming the opposite main sides, and / or

[0030] - each feed PCB comprises a center line, where the overlapping parts of two conductor parts are positioned between the center line and the loop elements, and / or

[0031] - each conductor part formed on the first main side of each feed PCB comprises a ground connection and a port connector.

[0032] According to some further aspects, for each feed PCB, a conductor part formed on the second main side of the feed PCB ends in an open circuit and has a width that increases toward the end from a first width to a second width. These conductor parts thus form open stubs having a one-side-tapered shape that confers an increased overall bandwidth at the lower frequencies and at the upper frequencies in the frequency band of operation. This is due to the fact that the open stubs will enable an imaginary part of an input impedance to be eliminated, improving the overall return loss performance. The tapered open stubs create a coupled effect to the loop elements at the same time, while they can be kept at a sufficient distance from the loop elements. According to some aspects, for each feed PCB, a conductor part formed on a second main side of the feed PCB is connected to the unbalanced port connector via a further transmission line. According to some further aspects, for each feed PCB, the conductor parts formed on the second main side are connected by a connecting transmission line.

[0033] It follows from the above that the balun feeding arrangements mainly can be formed in a conventional manner with conventional methods.

[0034] According to some aspects, the dipole arms are formed on a first main side of an antenna PCB that lies in the first plane. This provides a dual polarized dipole antenna arrangement with a very rigid and durable structure that is easy to assemble, for example in a pick-and-place process. This results in a dipole antenna arrangement that is inexpensive to manufacture, for example compared to some other type of dipole antenna arrangement structure such as a structure formed in stamped metal sheets.

[0035] According to some aspects, for each dipole arm there is a pair of coupling conductors formed on a second main side of the antenna PCB, arranged symmetrically opposite the dipole arms and adapted to be capacitively coupled to the respective dipole arm. The coupling conductors provide an enhanced capacitive coupling of the electric field through the antenna PCB, where the capacitive coupling causes a reduced capacitance reactance effect for the dipole arms, and thus the input impedance at the highest frequencies of operation will be shifted to a more inductive region. This means that the input impedance is transformed and that the radiation properties are improved at the highest frequencies of operation

[0036] According to some further aspects, each coupling conductor is adapted to be capacitively coupled to a respective loop element. This results in a more compact dipole antenna arrangement and enables an improvement of the antenna performance over the frequency band of operation.

[0037] According to some yet further aspects, each coupling conductor has an arrow-shape that points towards a closest edge of the antenna PCB. The arrow-shaped coupling conductors have been formed to have a certain shape, position and area with respect to dipole arm geometry to enhance desired capacitive coupling effects and to prevent undesired coupling.

[0038] According to some aspects, each dipole arm comprises a central portion and two sub-arms that are connected to, and partially circumvent, the central portion. This provides an increased dipole arm length at the same available area such that the size of the antenna PCB can be minimized, keeping the dimensions of the dipole antenna arrangement relatively small

[0039] According to some aspects, each loop element is constituted by a corresponding loop conductor that is associated with an average width, and a shortest distance between a dipole arm and the corresponding loop conductor is less than 2 times the average width, preferably less than 1 times the average width. This opens up for adjustments of the loop conductor that for example can enhance return loss characteristics.

[0040] This object is also achieved by means of linear array antenna and two-dimensional array antennas that are associated with the above advantages.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present disclosure will now be described more in detail with reference to the appended drawings, where:

[0043] Figure 1 shows a schematic front view of an array antenna;

[0044] Figure 2 shows a circuit diagram of a Marchand balun;

[0045] Figure 3 shows a schematic top perspective view of a dipole antenna arrangement;

[0046] Figure 4 shows a schematic bottom perspective view of the dipole antenna arrangement;

[0047] Figure 5 shows a side view of the dipole antenna arrangement;

[0048] Figure 6 shows a top view of an antenna PCB;

[0049] Figure 7 shows a bottom view of the antenna PCB;

[0050] Figure 8 shows a first side view of a first feed PCB;

[0051] Figure 9 shows a second side view of the first feed PCB;

[0052] Figure 10 shows a first side view of a second feed PCB;

[0053] Figure 11 shows a second side view of the second feed PCB; and

[0054] Figure 12-17 show different examples of sets of loop elements.

[0055] DETAILED DESCRIPTION

[0056] Aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The different devices, systems, computer programs and methods disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout. The terminology used herein is for describing aspects of the disclosure only and is not intended to limit the present disclosure. 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.

[0057] Figure 1 shows a two-dimensional array antenna 100 comprising at least one row 103, 104 of linear array antennas 102, each row 103, 104 comprising two or more linear array antennas 102. Each linear array antenna 102 comprises a plurality of linearly arranged dipole antenna arrangements 101 , and such dipole antenna arrangements that are suitable for optimum performance in such an environment will be disclosed in the following.

[0058] With reference to Figure 3-Figure 11 , there is a dipole antenna arrangement 300 comprising a first dipole arm 301 and a second dipole arm 302 which form a first dipole antenna element 301 , 302 that runs along a first antenna extension E1 and runs parallel to a first plane P1. The dipole antenna arrangement 300 further comprises a first balun feeding arrangement 305 that is adapted to feed the first dipole antenna element 301 , 302 and is formed on opposite main sides 335, 336 of a first feed printed circuit board (PCB) 310 that runs in a second plane P2 that is separate from the first plane P1. According to some aspects, as shown in the illustrated examples, the first plane P1 and the second plane P2 are mutually perpendicular.

[0059] According to the present disclosure, the first feed PCB 310 comprises at least one electrically conductive loop element 313a, 313b; 314a, 314b for each one of the first dipole arm 301 and the second dipole arm 302, wherein each loop element 313a, 313b; 314a, 314b comprises a respective loop conductor arranged on one of the main sides 335, 336 of the first feed PCB 310 such that it is adapted to be capacitively coupled to a respective dipole arm 301 , 302 of the first feed PCB 310.

[0060] The introduction of the capacitively coupled loop elements 313a, 313b; 314a, 314b results in an increased electrical length of the dipole arms 301 , 302 without increasing their physical sizes. This enables a small physical separation with respect to dipole arms of adjacent dipole elements in an array antenna while also having increased return loss characteristics, particularly at lower frequencies in the operational bandwidth, without impairing the radiation pattern of the dipole antenna arrangement 300. This provides an increased frequency band of operation. The loop elements 313a, 313b; 314a, 314b may for example act as resonators.

[0061] In other words, the size of the dipole antenna element 301 , 302 can be extended electrically instead of being physically larger which is beneficial due to limited space. Since it is difficult to make copper parts extending physically from the dipole antenna element 301, 302, the loop elements 313a, 313b; 314a, 314b are formed on the first feed PCB 310 and positioned close enough to the dipole antenna element 301 , 302 to enable a positive interaction that enables the size of the dipole antenna element 301 , 302 to be extended electrically. According to some aspects, as shown in the illustrated examples, the first feed PCB 310 comprises loop elements 313a, 313b; 314a, 314b formed on opposite main sides 335, 336 of the first feed PCB 310, such that pairs 313a, 313b; 314a, 314b of opposing loop elements are formed, where each pair 313a, 313b; 314a, 314b; of opposing loop elements is positioned opposite a respective dipole arm 301 , 302.

[0062] Having loop elements 313a, 313b; 314a, 314b formed on opposite main sides 335, 336 of the feed PCB 310 results in that they couple to the respective dipole arm 301 , 302 from both sides of the feed PCB 310 symmetrically, making the design more compact and enabling the radiation pattern to become more symmetrical with respect to boresight.

[0063] Regarding baluns, there exists a plethora of balun circuits; a common configuration is the so-called Marchand balun as shown in a circuit diagram in Figure 2. According to some aspects, with reference to Figure 2-Figure 11 , the first balun feeding arrangement 205, 305 is constituted by a Marchand balun and comprises a first coupled transmission line pair 206, 306, a second coupled transmission line pair 207, 307, a first unbalanced port connector 208, 308 and a first balanced port 209, 309. The coupled transmission line pairs 206, 207; 306, 307 are formed on opposite main sides 335, 336 of the first feed PCB 310, where the first balanced port 209, 309 comprises a first port connector 211 , 311 and a second port connector 212, 312. The first port connector 211 , 311 is connected to the first dipole arm 301 via a first arm connection 339, and where the second port connector 211 , 312 is connected to the second dipole arm 302 via a second arm connection 340,

[0064] For example, an input signal is fed to the first unbalanced port connector 208 that is connected to a first conductor part 228 of the first coupled transmission line pair 206, and a second conductor part 230 of the second coupled transmission line pair 207, which conductor parts 228, 230 are connected in series. The second conductor part 230 is terminated in an open circuit 250. A differential signal is extracted from a third conductor part 227 of the first coupled transmission line pair 206 and a fourth conductor part 229 of the second coupled transmission line pair 207, where each of these conductor parts 227, 229 is terminated in a short circuit / ground connection 246, 247. The balun feeding arrangement 305 as realized and used in the dipole antenna arrangement 300 will be described more in detail later.

[0065] Using a Marchand balun as a balun feeding arrangement is only an example, other types of balun feeding arrangements are of course possible. This means that many common and well-known types of balun feeding arrangements can be used in the dipole antenna arrangement 300.

[0066] According to some aspects, the first antenna extension E1 runs along the second plane P2. This means that the dipole arms 301 , 302 run along the second plane P2. According to some further aspects, the first plane P1 and the second plane P2 are mutually perpendicular. This means that the first feed PCB 310 runs perpendicular to the dipole arms 301 , 302, which enables an uncomplicated, easily assembled and stable configuration of the dipole antenna arrangement 300. Furthermore, a relatively uncomplicated dipole antenna arrangement structure is obtained, being relatively inexpensive to manufacture and easy to assemble. According to some aspects, the dipole antenna arrangement 300 further comprises a third dipole arm 315 and a fourth dipole arm 316 which form a second dipole antenna element 315, 316 that runs along a second antenna extension E2 and runs parallel to the first plane P1. The dipole antenna arrangement 300 also comprises a second balun feeding arrangement 205, 317 that is adapted to feed the second dipole antenna element 315, 316 and is formed on opposite main sides 337, 338 of a second feed PCB 322 that runs in a third plane P3 that is separate from the first plane P1 and the second plane P2. The second feed PCB 322 comprises at least one electrically conductive loop element 325a, 325b; 326a, 326b for each one of the third dipole arm 315 and the fourth dipole arm 316. Each loop element 325a, 325b; 326a, 326b comprises a respective loop conductor arranged on one of the main sides 337, 338 of the second feed PCB 322 such that it is adapted to be capacitively coupled to a respective dipole arm 315, 316 of the second feed PCB 322.

[0067] Having a first dipole antenna element 301 , 302 and a second dipole antenna element 315, 316 enables the dipole antenna arrangement 300 to be adapted for two different polarizations. It is to be understood that the second dipole antenna element 315, 316 is associated with the same advantages as the first dipole antenna element 301 , 302, being of the same or similar design.

[0068] According to some aspects, and with reference also to Figure 2, the second balun feeding arrangement 205, 317 corresponds to the first balun feeding arrangement and is thus constituted by a Marchand balun and comprises a third coupled transmission line pair 206, 318, a fourth coupled transmission line pair 207, 319, a second unbalanced port connector 208, 320 and a second balanced port 209, 321 , where the coupled transmission line pairs 206, 207; 318, 319 are formed on opposite main sides 337, 338 of the second feed PCB 322, where the second balanced port 209, 321 comprises a third port connector 211 , 342 and a fourth port connector 212, 343, where the third port connector

[0069] 211 , 343 is connected to the third dipole arm 302 via a third arm connection 344 and the where the fourth port connector

[0070] 212, 343 is connected to the fourth dipole arm 316 via a fourth arm connection 345.

[0071] Regarding the illustration of the balun feeding arrangements 305, 317, Figure 2 shall be regarded as a common general schematic representation of a Marchand balun, and is applicable for both balun feeding arrangements 305, 317.

[0072] Each feed PCB 310, 322 thus comprises a feeding line side and a grounding side.

[0073] Using a Marchand balun as a balun feeding arrangement is only an example in this case as well, other types of balun feeding arrangements are of course possible. This means that many common and well-known types of balun feeding arrangements can be used in the dipole antenna arrangement 300. The two balun feeding arrangements 305, 317 need not be of the same type, but can be of mutually different designs if desired.

[0074] According to some aspects, first plane P1 , the second plane P2 and the third plane P3 are mutually perpendicular, and the second antenna extension E2 runs along the third plane P3 and is perpendicular to the first antenna extension E1 . This means that the first feed PCB 310 runs perpendicular to the second feed PCB 322, and that the PCBs 310, 322 run perpendicular to the dipole antenna elements 301 , 302; 315, 316, which enables an uncomplicated, easily assembled and stable configuration of the dipole antenna arrangement 300, being relatively inexpensive. This also means that the first dipole antenna element 301 , 302 and the second dipole antenna element 315, 316 are adapted for mutually orthogonal polarizations.

[0075] According to some aspects, as for the first feed PCB 310, the second feed PCB 322 comprises loop elements 325a, 325b; 326a, 326b formed on opposite main sides 337, 338 of the second feed PCB 322, such that pairs 325a, 325b; 326a, 326b of opposing loop elements are formed. Each pair 325a, 325b; 326a, 326b of opposing loop elements is positioned opposite a respective dipole arm 315, 316. The advantages of this configuration are discussed above.

[0076] According to some aspects, each loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b is constituted by a corresponding loop conductor.

[0077] According to some aspects, with reference also to Figure 12-Figure 15, each feed PCB 310, 322 comprises a set of loop elements 401 a, 401 b; 402a, 402b; 403a, 403b; 404a; 404b, where at least one loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b in a set of loop elements 401 a, 401 b; 402a, 402b; 403a, 403b; 404a; 404b comprises a loop conductor that runs in a closed loop. A closed loop geometry reduces the possibility of having undesired resonance / peak issues for the antenna return loss within the frequency band of operation.

[0078] However, should there occur undesired return loss peaks, these may be shifted to occur outside of the frequency band of operation by careful design of a gap formed in the loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b, possibly together with a corresponding increase of the total loop element conductor length. Therefore, with reference also to Figure 16 and Figure 17, according to some aspects, each feed PCB 310, 322 comprises a set of loop elements 501 a, 501 b; 502a, 502b, where at least one loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b in a set of loop elements 501 a, 501 b; 502a, 502b comprises a loop conductor that runs in an open loop, where the loop is open is open by means of a corresponding gap Gi, G2.

[0079] According to some aspects, at least one loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b comprises a loop conductor that runs in a C-shape where such a folded geometry enables the loop conductor to have sufficient length. As illustrated in Figure 12-Figure 15, the C-shaped (or U-shaped) loop conductor can be oriented in many different ways. The loop conductor orientation can be used for antenna tuning, since the loop conductor orientation affects coupling interaction between the loop conductor and the respective balun feeding arrangement 305, 317.

[0080] According to some aspects, the loop conductor of at least one loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b has an electrical length of a quarter wavelength, or an odd-numbered multiple of a quarter wavelength, of a frequency in a frequency band of operation, preferably a frequency in the lower half of the frequency band of operation, and more preferably a frequency in the lower quarter of the frequency band of operation. The loop element structure can be adapted for an extended frequency band of operation by adapting the loop length with a correct fraction in terms of with odd-numbered multiples the quarter wavelength at the frequency band of operation and considering the loop conductor width by taking into account the dielectric properties of the feed PCBs 310, 322.

[0081] According to some aspects, at least one loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b is positioned to be most adjacent to a part of the corresponding dipole arm 301 , 302; 315, 316 that is farthest away from an intersection between the second plane P2 and the third plane P3.

[0082] According to some further aspects, each loop element is constituted by a corresponding loop conductor 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b that is associated with an average width WA, and a shortest distance ds between a dipole arm 301 , 302; 315, 316 and the corresponding loop conductor 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b is less than 2 times the average width WA, preferably less than 1 times the average width WA.

[0083] As illustrated in Figure 12-Figure 15, the width of the loop conductors 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b can be varied during the length of the loop conductor 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b for minor changes / improvements of return loss characteristics. In Figure 15, the loop conductor 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b is shown having a uniform width. Above, an average loop conductor width WA is mentioned.

[0084] By placing the loop elements on outer corners of the feed PCBs 310, 322 and positioning them under the dipole arms 301 , 302; 315, 316 with a small optimum gap ds to the corresponding dipole arms 301 , 302; 315, 316 the coupling between the loop elements and the corresponding dipole arms 301 , 302; 315, 316 will be increased.

[0085] In the following, it will be described more in detail how the balun feeding arrangement 305, 317 are realized in the illustrated examples.

[0086] According to some aspects, for each feed PCB 310, 322, each coupled transmission line pair 206, 207; 306, 307; 318, 319 comprises overlapping parts of two conductor parts 227, 228; 229, 230; 327, 328; 329, 330; 331 , 332; 333, 334. One conductor part 327, 329, 331 , 332 is formed on a first main side 335, 337 of the feed PCB 310, 322, and the other conductor part 328, 330, 332, 334 is formed on a second main side 336, 338 of the feed PCB 310, 322, the main sides 335, 336; 337, 338 forming the opposite main sides.

[0087] According to some aspects, each feed PCB 310, 322 comprises a center line C1 , C2, where the overlapping parts of two conductor parts 227, 228; 229, 230; 327, 328; 329, 330; 331 , 332; 333, 334 are positioned between the center line C1 , C2 and the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b. According to some further aspects, each conductor part 327, 329, 331 , 332 formed on the first main side 335, 337 of each feed PCB 310 comprises a ground connection 246, 247; 346, 347; 348, 349 and a port connector 211 , 212; 311 , 312; 342, 343. According to some aspects, for each feed PCB 310, 322, a conductor part 328, 332 formed on the second main side 336, 338 of the feed PCB 310, 322 ends in an open circuit 250 and has a width that increases toward the end from a first width wi to a second width W2.

[0088] These conductor parts 328, 332 thus form open stubs having a one-side-tapered shape that confers an increased overall bandwidth at the lower frequencies and at the upper frequencies in the frequency band of operation, providing an increased frequency band of operation. This is due to the fact that the open stubs 328, 332 will enable an imaginary part of an input impedance to be eliminated, improving the overall return loss performance. The tapered open stubs 328, 332 create a coupled effect to the loop elements at the same time, while they can be kept at a sufficient distance from the loop elements.

[0089] In this context, the input impedance relates to the input impedance at the respective unbalanced port connector 308, 320, and thus relates to the input impedance of the respective balun feeding arrangement 305, 317 and corresponding dipole antenna element 301 , 302; 315, 316 when the dipole antenna arrangement 300 is assembled.

[0090] According to some aspects, for each feed PCB 310, 322, a conductor part 330, 334 formed on a second main side 336, 338 of the feed PCB 310, 322 is connected to the unbalanced port connector 308, 320 via a further transmission line 351, 352. According to some further aspects, for each feed PCB 310, 322, the conductor parts 328, 330; 332, 334 formed on the second main side 336, 338 are connected by a connecting transmission line 362, 363. The balun feeding arrangements 305, 317 can thus mainly be formed in a conventional manner with conventional methods.

[0091] According to some aspects, the dipole arms 301 , 302; 315, 316 are formed on a first main side 303 of an antenna PCB 304 that lies in the first plane P1 . This means that the feed PCBs 310, 322 can be oriented in a cross-shape with the antenna PCB 304 place on top, as for example illustrated in Figure 3 and Figure 4, such that the antenna extensions E1 , E2 are mutually perpendicular, the PCBs 304, 310, 322 being respective planar structures. This provides a dual polarized dipole antenna arrangement 300 with a very rigid and durable structure that is easy to assemble, for example in a pick-and-place process. This results in a dipole antenna arrangement 300 that is inexpensive to manufacture, for example compared to some other type of dipole antenna arrangement structure such as a structure formed in stamped metal sheets.

[0092] As illustrated in Figure 6-Figure 9, the first port connector 31 1 and the second port connector 312 are formed on the first main side 335 of the first feed PCB 310, and on the opposite second main side 336 of the first feed PCB 310 there are corresponding solder attachment pads 378, 379. The first feed PCB 310 further comprises two outer sets of opposite solder attachment pads 375, 379; 376, 377. The port connectors 311 , 312 and the solder attachment pads 378, 379; 375, 379; 376, 377 are adapted to be inserted into corresponding arm connections 339, 340; 371 , 372 constituted by slots running through the antenna PCB 304. All solder attachment pads 378, 379; 375, 379; 376, 377 end up at the corresponding dipole arms 301 , 302 and are soldered into place such that the first feed PCB 310 is securely attached to the antenna PCB 304. Correspondingly, as illustrated in Figure 6, Figure 7, Figure 9 and Figure 11 , the third port connector 342 and the fourth port connector 343 are formed on the first main side 337 of the second feed PCB 322, and on the opposite second main side 338 of the second feed PCB 322 there are corresponding solder attachment pads 385, 386. The second feed PCB 322 further comprises two outer sets of opposite solder attachment pads 382, 384; 383, 387. The port connectors 342, 343 and the solder attachment pads 385, 386; 382, 384; 383, 387 are adapted to be inserted into corresponding arm connections 344, 345; 373, 374 constituted by slots running through the antenna PCB 304. All solder attachment pads 385, 386; 382, 384; 383, 387 end up at the corresponding dipole arms 315, 316 and are soldered into place such that the second feed PCB 322 is securely attached to the antenna PCB 304 in the same manner as the first feed PCB 310.

[0093] According to some aspects, as in particular illustrated in Figure 4 and Figure 7, for each dipole arm 301 , 302; 315, 316, there is a pair of coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b formed on a second main side 353 of the antenna PCB 304, arranged symmetrically opposite the dipole arms 301 , 302; 315, 316 and adapted to be capacitively coupled to the respective dipole arm 301 , 302; 315, 316.

[0094] The coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b provide an enhanced capacitive coupling of the electric field through the antenna PCB 304, where the capacitive coupling causes a reduced capacitance reactance effect for the dipole arms 301 , 302; 315, 316, and thus the input impedance at the highest frequencies of operation will be shifted to a more inductive region. This means that the input impedance is transformed and that the radiation properties are improved at the highest frequencies of operation. The coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b have been designed and optimized in view of the position, dimension and shape of the dipole arms 301 , 302; 315, 316. The lengths of the coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b have been determined with respect to half the length of each dipole arm 301 , 302; 315, 316, and their widths have been adjusted in view of the arm connections 339, 340; 371, 372; 344, 345; 373, 374. The coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b have been positioned with a distance from each other to provide an optimum result while avoiding undesired coupling.

[0095] According to some further aspects, each coupling conductor 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b is adapted to be capacitively coupled to a respective loop element 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b. The coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b co-operate with the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b since they are positioned at the sides the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b, being positioned diagonally and symmetrically along the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b. This results in that the dipole antenna elements 301 , 302; 316, 317 are positioned electrically closer to the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b. This results in a more compact dipole antenna arrangement 300 and enables an improvement of the antenna performance over the frequency band of operation. For example, as illustrated in Figure 4 and Figure 7, each coupling conductor 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b has an arrow-shape that points towards a closest edge of the antenna PCB 304.

[0096] The arrow-shaped coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b have been formed to have a certain shape, position and area with respect to dipole arm geometry to enhance desired capacitive coupling effects and to prevent undesired coupling. In this context, desired capacitive coupling effects contribute to a desired input impedance matching over a wider frequency band of operation, while undesired coupling for example may result in undesired resonance peaks.

[0097] According to some further aspects, each dipole arm 301, 302; 315, 316 comprises a central portion 361 , 358; 359, 360 and two sub-arms 361 a, 361 b; 358a, 358b, 359a, 359b; 360a, 360b that are connected to, and partially circumvent, the central portion 361, 358, 359; 360. The dipole arms 301 , 302; 315, 316 have been designed with that shape due to implementing some apertures and dividing into the branches, or sub-arms 361 a, 361 b; 358a, 358b, 359a, 359b; 360a, 360b, from both side around a triangle-shaped part of the central portion 361 , 358, 359; 360 to provide an increased dipole arm length. This results in that the size of the antenna PCB 304 can be minimized, keeping the dimensions of the dipole antenna arrangement 300 relatively small. The triangle-shaped part of the central portion 361, 358, 359; 360 between each set of two sub-arms 361 a, 361 b; 358a, 358b, 359a, 359b; 360a, 360b provides desired coupling properties with a proper gap value implemented to keep them sufficiently far away from each other to prevent undesired interaction and resonances.

[0098] In the illustrated examples, each dipole arm 301 , 302; 315, 316 is formed symmetrically and separately. The dipole arms 301 , 302; 315, 316 separated from each other, i.e., they are not connected to each other physically.

[0099] As described above, the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b as well as possibly also the coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b and / or the tapered open stubs 328, 332 are described to be comprised in the dipole antenna arrangement 300.

[0100] - The loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b provide increased electrical length for the dipole arms 301 , 302; 315, 316 without increasing their physical size.

[0101] - The coupling conductors 354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b create a capacitive coupling that provides an improved input impedance matching.

[0102] - The tapered open stubs 328, 332 create a positive coupling effect via the loop elements 313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b, optimizing overall return loss performance.

[0103] Each one of these additional parts contribute to enabling the dipole antenna arrangement 300 to be compact while having desired antenna characteristics such as being adapted to operate in a relatively broad frequency band, in particular in several adjacent and / or separate frequency bands. Each one of the additional parts confers a positive impact such that a combination of them provides an optimum antenna characteristics. With reference to Figure 1 -Figure 17, the present disclosure also relates to a linear array antenna 102 comprising a plurality of linearly arranged dipole antenna arrangements 101 , 300 as described herein.

[0104] Furthermore, the present disclosure also relates to a two-dimensional array antenna 100 comprising at least one row 103, 104 of such linear array antennas 102, each row 103, 104 comprising two or more linear array antennas 102.

[0105] By means of the dipole antenna arrangement 300 as described above, the distance between neighboring columns of linear array antennas 102 can be less than half wavelength for the frequency band of operation, providing increased isolation properties and mitigating the couplings between the dipole antenna arrangement 300 by having a sufficiently good input impedance matching.

[0106] The term coupling refers to electromagnetic coupling.

[0107] Expressions such as perpendicular are not to be interpreted as being mathematically exact, but to be within what normally is practically obtainable in the present technical field.

[0108] The present disclosure is not limited to the examples provided above, but may vary freely within the scope of the appended claims. As mentioned previously, each feed PCB 310, 322 comprises a respective unbalanced port connector 308, 320 and ground connections 346, 347; 348, 349. For example, as illustrated in Figure 8 and Figure 9, the ground connections 346, 347 of the first feed PCB 310 are formed on the first main side 335 of the first feed PCB 310, and on the opposite second main side 336 of the first feed PCB 310, the first unbalanced port connector 308 and a solder attachment pad 381 are formed opposite the ground connections 346, 347. Correspondingly, as illustrated in Figure 10 and Figure 11 , the ground connections 348, 349 of the second feed PCB 322 are formed on the first main side 337 of the second feed PCB 322, and on the opposite second main side 338 of the second feed PCB 322, the second unbalanced port connector 320 and a solder attachment pad 388 are formed opposite the ground connections 348, 349.

[0109] The unbalanced port connectors 308, 320, ground connections 346, 347; 348, 349 and solder attachment pad 381 , 388 are formed on protrusions that can be inserted into corresponding attachment slots (not shown) in an array antenna PCB, and soldered into place. In this way, each dipole antenna arrangement 300 can be securely attached to form an array antenna 100, and this procedure can for example be performed in a pick-and-place process.

[0110] In these examples, each PCB 304, 310, 322 is formed as a dielectric material sheet with copper claddings on the main sides, where copper has been partially removed to form the metal structures on each main side, for example by means of etching. Generally, in this context a PCB can comprise several layers of dielectric material sheets with metal layers formed on the outer main sides as well as sandwiched between them. Such intermediate metal layers can for example by used as signal layers where microwave signals, digital signals and voltage supplies can be routed. Using copper is of course only an example, other metals are of course possible such as silver and gold. Silver and gold can also be used as plating materials for a base metals such as copper. The dielectric material can be of many types, for example glass-fiber re-enforced epoxy or Polytetrafluoroethylene (PTFE) as well as different types of ceramic materials. A PCB can comprise layers of different mixed dielectric materials.

Claims

CLAIMS1 . A dipole antenna arrangement (300) comprising a first dipole arm (301) and a second dipole arm (302) which form a first dipole antenna element (301 , 302) that runs along a first antenna extension (E1) and runs parallel to a first plane (P1), the dipole antenna arrangement (300) further comprising a first balun feeding arrangement (205, 305) adapted to feed the first dipole antenna element (301 , 302) and being formed on opposite main sides (335, 336) of a first feed printed circuit board, PCB, (310) that runs in a second plane (P2) that is separate from the first plane (P1), wherein the first feed PCB (310) comprises at least one electrically conductive loop element (313a, 313b; 314a, 314b) for each one of the first dipole arm (301) and the second dipole arm (302), wherein each loop element (313a, 313b; 314a, 314b) comprises a respective loop conductor arranged on one of the main sides (335, 336) of the first feed PCB (310) such that it is adapted to be capacitively coupled to a respective dipole arm (301 , 302) of the first feed PCB (310).

2. The dipole antenna arrangement (300) according to claim 1 , wherein the first balun feeding arrangement (205, 305) comprises a first coupled transmission line pair (206, 306), a second coupled transmission line pair (207, 307), a first unbalanced port connector (208, 308) and a first balanced port (209, 309), where the coupled transmission line pairs (206, 207; 306, 307) are formed on opposite main sides (335, 336) of the first feed PCB (310), where the first balanced port (209, 309) comprises a first port connector (211 , 311) and a second port connector (212, 312), where the first port connector (211, 311) is connected to the first dipole arm (301) via a first arm connection (339), and where the second port connector (211 , 312) is connected to the second dipole arm (302) via a second arm connection (340).

3. The dipole antenna arrangement (300) according to any one of the claims 1 or 2, wherein the first antenna extension (E1) runs along the second plane (P2).

4. The dipole antenna arrangement (300) according to any one of the previous claims, wherein the first plane (P1) and the second plane (P2) are mutually perpendicular.

5. The dipole antenna arrangement (300) according to any one of the previous claims, further comprising a third dipole arm (315) and a fourth dipole arm (316) which form a second dipole antenna element (315, 316) that runs along a second antenna extension (E2) and runs parallel to the first plane (P1), the dipole antenna arrangement (300) further comprising a second balun feeding arrangement (205, 317) adapted to feed the second dipole antenna element (315, 316) and being formed on opposite main sides (337, 338) of a second feed PCB (322) that runs in a third plane (P3) that is separate from the first plane (P1) and the second plane (P2), where the second feed PCB (322) comprises at least one electrically conductive loop element (325a, 325b; 326a, 326b) for each one of the third dipole arm (315) and the fourth dipole arm (316), wherein each loop element (325a, 325b; 326a, 326b) comprises a respective loop conductor arranged on one of the main sides (337, 338) of the second feed PCB (322) such that it is adapted to be capacitively coupled to a respective dipole arm (315, 316) of the second feed PCB (322).

6. The dipole antenna arrangement (300) according to claim 5, wherein the second balun feeding arrangement (205, 317) comprises a third coupled transmission line pair (206, 318), a fourth coupled transmission line pair (207, 319), a second unbalanced port connector (208, 320) and a second balanced port (209, 321), where the coupled transmission line pairs (206, 207; 318, 319) are formed on opposite main sides (337, 338) of the second feed PCB (322), where the second balanced port (209, 321) comprises a third port connector (211 , 342) and a fourth port connector (212, 343), where the third port connector (211, 343) is connected to the third dipole arm (302) via a third arm connection (344) and the where the fourth port connector (212, 343) is connected to the fourth dipole arm (316) via a fourth arm connection (345).

7. The dipole antenna arrangement (300) according to any one of the claims 5 or 6, wherein the first plane (P1), the second plane (P2) and the third plane (P3) are mutually perpendicular, and where the second antenna extension (E2) runs along the third plane (P3) and is perpendicular to the first antenna extension (E1).

8. The dipole antenna arrangement (300) according to any one of the previous claims, wherein there are loop elements (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) formed on opposite main sides (335, 336; 337, 338) of each feed PCB (310, 322), such that pairs (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) of opposing loop elements are formed, where each pair (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) of opposing loop elements is positioned opposite a respective dipole arm (301, 302; 315, 316).

9. The dipole antenna arrangement (300) according to any one of the previous claims, wherein each feed PCB (310, 322) comprises a set of loop elements (401a, 401b; 402a, 402b; 403a, 403b; 404a; 404b), where at least one loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) in a set of loop elements (401a, 401b; 402a, 402b; 403a, 403b; 404a; 404b) comprises a loop conductor that runs in a closed loop.

10. The dipole antenna arrangement (300) according to any one of the previous claims, wherein each feed PCB (310, 322) comprises a set of loop elements (501a, 501 b; 502a, 502b), where at least one loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) in a set of loop elements (501a, 501b; 502a, 502b) comprises a loop conductor that runs in an open loop, where the loop is open is open by means of a corresponding gap (Gi, G2).11 . The dipole antenna arrangement (300) according to any one of the previous claims, wherein at least one loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) comprises a loop conductor that runs in a C- shape.

12. The dipole antenna arrangement (300) according to any one of the previous claims, wherein the loop conductor of at least one loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) has an electrical length of a quarter wavelength, or an odd-numbered multiple of a quarter wavelength, of a frequency in a frequency band of19 operation, preferably a frequency in the lower half of the frequency band of operation, and more preferably a frequency in the lower quarter of the frequency band of operation.

13. The dipole antenna arrangement (300) according to any one of the previous claims, wherein at least one loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) is positioned to be most adjacent to a part of the corresponding dipole arm (301 , 302; 315, 316) that is farthest away from an intersection between the second plane (P2) and the third plane (P3).

14. The dipole antenna arrangement (300) according to any one of the previous claims, wherein, for each feed PCB (310, 322), each coupled transmission line pair (206, 207; 306, 307; 318, 319) comprises overlapping parts of two conductor parts (227, 228; 229, 230; 327, 328; 329, 330; 331 , 332; 333, 334), where one conductor part (327,329, 331, 332) is formed on a first main side (335, 337) of the feed PCB (310, 322), and the other conductor part (328,330, 332, 334) is formed on a second main side (336, 338) of the feed PCB (310, 322), the main sides (335, 336; 337, 338) forming the opposite main sides.

15. The dipole antenna arrangement (300) according to claim 14, wherein each feed PCB (310, 322) comprises a center line (C1 , C2), where the overlapping parts of two conductor parts (227, 228; 229, 230; 327, 328; 329, 330; 331 , 332; 333, 334) are positioned between the center line (C1 , C2) and the loop elements (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b).

16. The dipole antenna arrangement (300) according to any one of the claims 14 or 15, wherein each conductor part (327, 329, 331 , 332) formed on the first main side (335, 337) of each feed PCB (310) comprises a ground connection (246, 247; 346, 347; 348, 349) and a port connector (211 , 212; 311 , 312; 342, 343).

17. The dipole antenna arrangement (300) according to any one of the claims 14-16, wherein, for each feed PCB (310, 322), a conductor part (328, 332) formed on the second main side (336, 338) of the feed PCB (310, 322) ends in an open circuit (250) and has a width that increases toward the end from a first width (wi) to a second width (W2).

18. The dipole antenna arrangement (300) according to any one of the claims 14-17, wherein, for each feed PCB (310, 322), a conductor part (330, 334) formed on a second main side (336, 338) of the feed PCB (310, 322) is connected to the unbalanced port connector (308, 320) via a further transmission line (351 , 352).

19. The dipole antenna arrangement (300) according to any one of the claims 14-18, wherein, for each feed PCB (310, 322), the conductor parts (328, 330; 332, 334) formed on the second main side (336, 338) are connected by a connecting transmission line (362, 363).2020. The dipole antenna arrangement (300) according to any one of the previous claims, wherein the dipole arms (301 , 302; 315, 316) are formed on a first main side (303) of an antenna PCB (304) that lies in the first plane (P1).21 . The dipole antenna arrangement (300) according to claim 20, wherein, for each dipole arm (301 , 302; 315, 316) there is a pair of coupling conductors (354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b) formed on a second main side (353) of the antenna PCB (304), arranged symmetrically opposite the dipole arms (301 , 302; 315, 316) and adapted to be capacitively coupled to the respective dipole arm (301 , 302; 315, 316).

22. The dipole antenna arrangement (300) according to claim 21 , wherein each coupling conductor (354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b) is adapted to be capacitively coupled to a respective loop element (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b).

23. The dipole antenna arrangement (300) according to claim 22, wherein each coupling conductor (354a, 354b; 355a, 355b; 356a, 356b, 357a, 357b) has an arrow-shape that points towards a closest edge of the antenna PCB (304).

24. The dipole antenna arrangement (300) according to any one of the previous claims, wherein each dipole arm (301 , 302; 315, 316) comprises a central portion (361 , 358; 359, 360) and two sub-arms (361a, 361 b; 358a, 358b, 359a, 359b; 360a, 360b) that are connected to, and partially circumvent, the central portion (361 , 358, 359; 360).

25. The dipole antenna arrangement (300) according to any one of the previous claims, wherein each loop element is constituted by a corresponding loop conductor (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) that is associated with an average width (WA), and where a shortest distance (ds) between a dipole arm (301 , 302; 315, 316) and the corresponding loop conductor (313a, 313b; 314a, 314b; 325a, 325b; 326a, 326b) is less than 2 times the average width (WA), preferably less than 1 times the average width (WA).

26. A linear array antenna (102) comprising a plurality of linearly arranged dipole antenna arrangements (101 , 300) according to any one of the previous claims.

27. A two-dimensional array antenna (100) comprising at least one row (103, 104) of linear array antennas (102) according to claim 26, each row (103, 104) comprising two or more linear array antennas (102).

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