ANTENNA DEVICE FOR A BASE STATION ANTENNA SYSTEM

Abstract

An antenna device is described. The antenna device 100 comprises at least two antenna elements each of comprising a first radiating element 110 and a corresponding second radiating element 120. The second radiating element 120 extends in a height direction along a common center axis A from a foot of the antenna device 100 to its corresponding first radiating element 110. The first radiating element 110 extends in a length direction outwards from the common center axis A. The length of the first radiating element 110 defines the maximum supported wavelength. Furthermore, each first radiating element 110 has a greater length than its width and each first radiating element 110 is electrically coupled to its corresponding second radiating element 120 along the length direction, so that the second radiating element 120 can contribute to the smaller wavelengths.

Claims

1. An antenna device (100) comprising at least two antenna elements, each antenna element comprising a first radiating element (110) and a corresponding second radiating element (120); wherein each second radiating element (120) extends in a height direction along a common center axis (A) from a foot of the antenna device (100) to its corresponding first radiating element (110); wherein each first radiating element (110) extends in a length direction outwards from the common center axis; wherein each first radiating element (110) has a length greater than its width; and wherein each first radiating element (110) is electrically coupled to its corresponding second radiating element (120) along the length direction.

2. The antenna device (100) according to claim 1, wherein the length of each of the first radiating elements (110) is at least two times greater than its width.

3. The antenna device (100) according to claim 1, wherein each of the second radiating elements (120) is planar.

4. An antenna device (100) according to claim 1, wherein each of the first radiating elements (110) comprises a strip portion which extends outwards from the common center axis in the length direction and at least one bent portion (113) which extends in an angle φ to the length direction, wherein 10°≦φ≦170°.

5. The antenna device (100) according to claim 1, wherein for each second radiating element (120) a length of the second radiating element (120) is smaller at the foot as the length at its corresponding first radiating element (110).

6. The antenna device (100) according to claim 1, wherein each second radiating element (120) comprises a first edge extending from the foot at least partially along the height direction to a first end of the second radiating element (120), the first end being arranged comparatively close to the common center axis and being coupled to the corresponding first radiating element (110); wherein each second radiating element (120) comprises a second edge extending from the foot to a second end of the second radiating element (120), the second end being arranged comparatively distant from the common center axis and being coupled to the corresponding first radiating element (110).

7. The antenna device (100) according to claim 1, wherein each first radiating element (110) of the antenna element comprises a bending edge extending in the length direction and electrically connecting the first radiating element (110) of the antenna element to the corresponding second radiating element (120) of the antenna element.

8. The antenna device (100) according to claim 7, wherein each second radiating element (120) comprises an opening (121) extending in the length direction from a first connection point between the second radiating element (120) and the corresponding first radiating element (110) to a second connection point between the second radiating element (120) and the corresponding first radiating element (110); wherein an area of the opening (121) is as at least as large as an area of a portion (126′) of the first radiating element (110), the portion (126′) extending in the length direction from the first connection point to the second connection point and in a width direction from the bending edge (128) to an edge (114) of the corresponding first radiating element (110).

9. The antenna device (100) according to claim 1, wherein each antenna element comprises an impedance transformer (130) arranged at a connection point electrically coupling the first radiating element (110) of the antenna element to the corresponding second radiating element (120) of the antenna element.

10. The antenna device (100) according to claim 1, wherein each antenna element is formed in a single piece.

11. The antenna device (100) according to claim 1, further comprising: an electrically conducting director element (140) being arranged in the height direction above the first radiating elements (110) and being supported by dielectric material (150) arranged between the director element (140) and the first radiating elements (110).

12. The antenna device (100) according to claim 11, wherein the director element (140) comprises per first radiating element (110) of the antenna element a corresponding aim (141) extending from the common center axis outwards in the same direction as the corresponding first radiating element (110).

13. The antenna device (100) according to claim 1, wherein the two antenna elements form a first pair of antenna elements and a dipole (160) of the antenna device.

14. The antenna device (100) according to claim 13, further comprising a second pair of antenna elements arranged around the common center axis and forming a second dipole of the antenna device.

15. The antenna device (100) according to claim 14, wherein the pairs of said antenna elements are arranged such that the second radiation elements of a respective pair form a 180° angle and the second radiation elements of two different pairs form a 90° angle.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0030] The main aspect and implementation forms of the present application will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

[0031] FIG. 1 shows a schematical view of an antenna device according to an embodiment of the present application.

[0032] FIG. 2 shows a schematical view the antenna device according to an embodiment of the present application.

[0033] FIG. 3 shows a top view of the antenna device according to an embodiment of the present application.

[0034] FIG. 4 shows a perspective view of the antenna device according to an embodiment of the present application.

[0035] FIG. 5 shows a top view of an antenna device according to an embodiment of the present application comprising an impedance transformer.

[0036] FIG. 6 shows the arrangement of the dielectric material.

[0037] FIG. 7 shows another arrangement of the dielectric material.

[0038] FIG. 8 shows a perspective view of the dipole according to an embodiment of the present application.

[0039] FIG. 9 shows the measurements of bandwidth performance.

[0040] FIG. 10 shows a perspective view of the first and the second radiating element.

[0041] FIG. 11 shows au arrangement of antenna devices according to an embodiment of the present application.

[0042] FIG. 12 shows another arrangement of antenna devices according to an embodiment of the present application.

[0043] FIG. 13 shows another arrangement of antenna devices according to an embodiment of the present application.

[0044] FIG. 14 shows another arrangement of antenna devices according to an embodiment of the present application.

[0045] FIG. 15 shows a capacitive connection between the first and the second radiating elements according to an embodiment of the present application.

DETAILED DESCRIPTION OF EMBODIMENTS

[0046] FIG. 1 shows an antenna device 100 for a base station according to an embodiment of the present application. The antenna device 100 comprises at least two antenna elements 105 and 106 each of which comprises a first radiating element 110 and a corresponding second radiating element 120. The second radiating element 120 extends in a height direction along a common center axis A from a foot 103 of the antenna device 100 to its corresponding first radiating element 110. The first radiating element 110 and the second radiating element 120 are preferably made of a (single) metal sheet.

[0047] The first radiating element 110 extends in a length direction LD outwards from the common center axis A. The length L of the first radiating element 110 defines the maximum supported wavelength. Furthermore, each first radiating element 110 has a greater length L than its width W (FIG. 3) and each first radiating element 110 is electrically coupled to its corresponding second radiating element 120 along the length direction LD, so that the second radiating element 120 can contribute to the smaller wavelengths.

[0048] The major contribution of embodiments of the present application is to reduce the low-band radiating element height, and therefore the overall antenna height H of the antenna device 100 can be reduced by 20-30%, while keeping base station class performance, particularly keeping the relative bandwidth greater than 30%.

[0049] Compared to other ultra broad band antennas, the maximum distance of the radiating system to the reflector is reduced by 20-30%. An overall antenna height H below 0.15λMAX can be achieved where the λMAX is the wavelength of the lowest supported frequency.

[0050] As also illustrated in FIG. 4 which is a perspective view of the antenna device 100, each of the second radiating elements 120 may be planar which allows manufacturing the antenna device 100 from a single metal sheet.

[0051] Preferably, the first radiating elements 110 of different antenna elements 105, 106 respectively have the same shape and/or size. Similarly, the second radiating elements 120 of different antenna elements 105, 106 may respectively have the same shape and/or size.

[0052] Further, each of the first radiating elements 110 may comprise a strip portion 111 which extends outwards from the common center axis in the length direction and at least one bent portion 113, which extends in an angle φ between 10° and 170° to the length direction, at the outermost part 112 of the strip portion 111 of the first radiating elements 110. The bent portion 113 may be built by using bent metal sheet technique.

[0053] Preferably, a length L2 of the second radiating element 120 at the foot 103 is smaller as the length L1 at its corresponding first radiating element 110.

[0054] An edge 122 along the height direction H of the second radiating element 120 is arranged to be very close to the common center axis A. The first upper end 123 of the edge 122 is coupled to the corresponding first radiating element 110. Another edge 124 of the second radiating element 120 extends from the foot 103 to a second upper end 125 of the second radiating element 120. As shown in FIG. 1, the second upper end 125 of the second radiating element 120 is coupled to the corresponding first radiating element 110, and comparing with the first upper end 123, the second upper end 125 of the second radiating element 120 is arranged distant from the common center axis A.

[0055] FIG. 2 shows a bending edge 114 of each first radiating element 110. The bending edge 114 extends in the length direction LD and electrically connects the first radiating element 110 of the antenna element to the corresponding second radiating element 120 of the antenna element.

[0056] The second radiating element 120 and the corresponding first radiating element 110 can be made out of a single metal sheet by cutting a U-shaped incision 126 in the upper part 127 of the second radiating element 120. The metal sheet formed the second radiating element 120 and the corresponding first radiating element 110 is bent along a bending edge 128 defined by two upper end points 129 of the U-shaped incision 126 in the second radiating element 120. As more clearly illustrated in FIG. 4 which is a perspective view of the antenna device, after the bending, the portion 126′ above U-shaped incision 126 forms a part of the strip portion 111 of the corresponding first radiating element 110, and the second radiating element 120 comprises now an opening 121 in place defined by the U-shaped incision 126 and the bending edge 128. Thus, as illustrated in FIGS. 2 and 4, the first radiating element 110 and the second radiating element 120 of each antenna element can be formed in a single piece.

[0057] The opening 121 is arranged between the first and the second upper ends 123 and 125 of the second radiating element 120 and extends in the length direction LD from a first connection point 171 between the second radiating element 120 and the corresponding first radiating element 110 to a second connection point 172 between the second radiating element 120 and the corresponding first radiating element 110.

[0058] The area of the opening 121 is as large as an area of the portion 126′ of the first radiating element 110 which corresponds to the U-shaped incision 126. Furthermore, the area of the opening 121 is larger than an area of the portion of the stripe portion of the first radiating element 110 from the first connection point 171 to the second connection point 172 and in a width direction from the bending edge 128 to the edge 114 corresponding to the U-shaped incision 126. Furthermore, an edge 115 opposite to the edge 114 forms another bending edge 115 of the first radiating element 110. Along this other bending edge 115 a further strip portion 115′ of the first radiating element 110 extends along the length direction of the first radiating element 110 in this example in a 90° angle to the strip portion 111. According to further embodiments the angle between the further strip portion 115′ and the strip portion 111 can be in a range >=10° and <=170°.

[0059] An important advantage is that the antenna elements can be built using bent metal sheet technology. This allows realizing the second radiating element 120 and the corresponding first radiating element 110 out of one single metallic sheet (without the need for soldering). Embodiments of the present application thus enable a highly degree of automation in the mass production process with all the advantages of the case.

[0060] Preferably, each of the second radiating elements 120 may have a substantial triangular portion 173 between its foot and its upper ends (cf. FIG. 1).

[0061] As shown in FIG. 4, a pair of antenna elements 105 and 106 forms a dipole of the antenna and two pairs of antenna elements 105, 106, 107 and 108 arranged around the common center axis. The two pairs of said antenna elements 105, 106, 107 and 108 are arranged such that the second radiation elements of a respective pair form a 180° angle and the second radiation elements of two different pairs form a 90° angle. That is to say, preferably, the two pairs of dipoles 105, 106, 107 and 108 are orthogonally or quasi-orthogonally arranged.

[0062] This allows to the dipole structure itself to maintain ultra broad band characteristics even reducing the overall height which respect to the ground plane<0.15 λmax. Indeed, the first radiating element 110, namely the largest dipole arm dimension, defines the maximum wavelength. The galvanically and/or capacitively connected second radiating element 120 gradually contributes to the smaller wavelengths. This enables the radiating elements 110 and 120 to support the wished bandwidth.

[0063] As shown in FIGS. 2, 3 and 4, a director element system comprising one or more director elements 140 (e.g. Disk, cross, cylinders, ring etc.) is placed on the antenna elements (dipoles) 105, 106, 107 and 108. The function of the director element system is to compensate the capacity to ground effect generated by the height reduction and in this way contributing to the broadband matching.

[0064] The director element system is not directly connected to ground. This has the advantage to introduce also an inductive component and by this way has the clear advantage to significantly improving the radiating element bandwidth.

[0065] As illustrated in FIG. 5, an impedance transformer 130 is integrated in the first radiating element 110 around the feed point 116. Each antenna element comprises an impedance transformer 130 arranged at the connection point 171 electrically coupling the first radiating element 110 of the antenna element to the corresponding second radiating element 120 of the antenna element.

[0066] It also can be seen from FIG. 5 that the length L of each of the first radiating elements 110 can be at least two times greater than the width W the first radiating elements 110.

[0067] The electrically conducting director element 140 is arranged in the height direction H above the first radiating elements 110 and being supported by dielectric material 150 arranged between the director element 140 and the first radiating elements 110. As shown in FIGS. 6 and 7, the additional dielectric material 150 is preferably placed e.g. between the 2 directors 140 and/or the directors 140 and the dipoles 105, 106, 107 and 108, and can be used for timing the bandwidth and as mechanical support for the antenna device 100.

[0068] The director element 140 comprises per first radiating element 110 of the antenna element a corresponding arm 141 extending from the common center axis outwards in the same direction as the corresponding first radiating element 110. Furthermore, at least in some examples, the director system is composed of 2 quasi elliptical orthogonal crosses as shown in FIG. 3.

[0069] FIG. 8 shows a perspective view of the arrangement of the dipoles according to an embodiment of the present application.

[0070] Specially, a realization example of a dual polarized antenna device (e.g. a low band radiator) is shown in FIGS. 2 to 8. The antenna device is composed by 2 pairs of radiating elements, each pair forming a dipole, placed 90 degree orthogonal regarding the geometrical center (the common center axis A). The two dipoles form a “cross-like” structure which supports the excitation of 2 orthogonal E-field polarizations. In this realization example, a bandwidth performance (VSWR<1.35 @relative bandwidth>35%) can be achieved. The second radiating elements 120 (dipole feet) are electrically connected to the first radiating elements 110 (the dipole arms). The mechanical and electrical material properties of the mounting system for the director 140 and the crosses formed by the dipoles shown in FIGS. 4 and 8 are chosen to optimize the bandwidth and stability performance.

[0071] In FIG. 9, it is shown by measurements that required bandwidth performance can be meet when even when reducing the height<40%.

[0072] FIG. 10 shows another embodiment of an antenna device 200. Accordingly, two antenna elements 205 and 206, each of which comprises a first radiating element 210 and a second radiating element 220, are arranged such that the second radiating elements of the two antenna elements form a 90° angle.

[0073] FIG. 11 shows an arrangement of several antenna devices 100. Accordingly, at least two antenna devices 100 are placed in a line along the length direction LD of the antenna device, and form a line of the antenna device array 300. Preferably, the lines defined by the length direction LD of the antenna device arrays 300 are arranged parallel to each other in a plane.

[0074] FIG. 12 shows a further arrangement of several antenna devices 100. Accordingly, at least two antenna devices 100 are placed parallel to each other and form an antenna device group 401. Preferably, at least two such antenna device groups 401 and 402 are arranged, so that a length direction LD1 of the antenna device in a first antenna device group 401 is perpendicular to a length direction LD2 of the antenna device in a second antenna device group 402.

[0075] FIG. 13 shows a further arrangement of several antenna devices 100. Accordingly, at least four antenna devices 100 form a rectangular antenna device group and each first radiating element 110 is arranged to be perpendicular to two neighboring first radiating elements, so that the first radiating elements 110 of the at least four antenna devices can form the rectangular antenna device group 500.

[0076] FIG. 14 shows an arrangement of several antenna devices 200 according to FIG. 10. Specially, at least four antenna devices 200 form a rectangular antenna device group 600. Each antenna devices 200 forms a right angle 601 of the rectangular antenna device group 600. Preferably, each first radiating element 110 of the four antenna devices 200 is arranged such that the outer end of the each first radiating element 110 faces and is close to the outer end of a first radiating element 110 of a neighboring antenna device 200.

[0077] The proportions between the height H from a reflector to the dipole feet and the length L of dipole anus (the first radiating element 110) are typically 1:4.

[0078] FIG. 15 shows a possible capacitive coupling 180 between the first radiating element and 110 the second radiating element 120 by using any suitable fastening means. e.g. clip, latch, hook or bolt fastening.

[0079] The present application has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed application, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.