Field of the invention

The present disclosure relates to a phase shift assembly for coupling to a feed network and an antenna comprising such a phase shift assembly. Technical background

In the prior art, phase shift assemblies for coupling to a feed network are well known.

Those phase shift assemblies are used in an antenna with a plurality of antenna elements for delaying the radio wave emitted by a particular antenna element so that the resulting emitted beam of radio waves is directed at a desired (down-tilt) angle. The phase shift or phase delay for realizing the desired (electric) down-tilt can be calculated according to the following formula. The equation shows the relation among phase delay (DF), wavelength (l), antenna element pitch (d) and down-tilt angle (qo):

In the antenna system, the element pitch (d) is usually fixed. Phase delay or phase difference (DF) basically can be taken as the physical path difference that the wave goes through. Therefore, by controlling either the wave length (l) or the phase difference (DF), the wanted down-tilt angle (Q0) can be achieved.

Thus, there are two basic ways to realize the desired down-tilt angle. A first way to realize the desired down-tilt angle is to change the wavelength in the dielectric. CN1028819638 relates to such a phase shifter and antenna. In this solution, the strip lines of different ports are covered with special dielectrics. When the electromagnetic wave goes through the dielectrics, the wavelength changes. According to the above equation, with proper changed wavelength and phase delay, the desired down-tilt angle can be achieved. A second way to realize the phase shift is by changing the length of the physical path of the respective emitted radio wave. US 6, 850, 130 relates to such a phase shift assembly. In this solution, when rotating a part, the physical length (phase delay DF) from an input to different output ports changes.

According to the equation, the desired down-tilt angle can thus be reached. A disadvantage of the prior art devices is that these devices can be difficultly used at high frequencies (3.5 GHz) and in MIMO (multiple input multiple output) systems. Currently, only one pre-set down-tilt angle is designed in such an antenna system; it is not possible to adjust the down-tilt angle when it is mounted to the site. Furthermore, the higher the frequency, the smaller the dimension, thereby requiring higher position requirements for the phase shifter parts. Besides that, these devices require a considerable cable connection, which means higher costs, heavy weight, and much space in the layout. In addition, the management of the prior art solutions in a stacked way results in thicker dimensions and is difficultly to implement in MIMO solutions.

Summary of the invention

Therefore, it is an object of the present invention to provide a phase shift assembly and an antenna, which overcome the afore-mentioned disadvantages. In particular, it is an object of the present invention to more precisely effect a down-tilt angle of the antenna, to avoid or at least reduce the cable connections, to make the phase shift assembly and the antenna more compact and easy to realize, in particular at low costs.

These and other objects, which become apparent upon reading the following description, are solved by the subject matter of the independent claims. The dependent claims refer to preferred embodiments of the invention.

According to a first aspect of the invention, a phase shift assembly for coupling to a feed network comprises: a first pair of dipole strip lines for coupling a first dipole element to the feed network, a second pair of dipole strip lines for coupling a second dipole element to the feed network, and a phase switcher comprising at least two pairs of strip lines. The phase switcher is configured to be moved to at least two positions, in which for each position, a pair of strip lines of the at least two pairs of strip lines connects the first pair of dipole strip lines with the second pair of dipole strip lines for effecting a phase difference between the first dipole element and the second dipole element. In the context of the present invention, “coupling” is preferably understood as connecting, in particular as directly or indirectly connecting.

In the context of the present invention, a phase difference, in particular the first phase difference, may be also 0, i.e. not present.

In other words, the present invention proposes a phase shift assembly, which can effect a phase difference or a phase shift by only moving the phase switcher to the at least two positions for accordingly connecting the pairs of dipole strip lines by way of the pairs of strip lines. Since the operator usually does not require a consecutive or continuous adjustment of the down-tilt angles of the antenna (i.e., a non-limiting number of down-tilt angles, e.g., all down-tilt angles in the range from 2° to 14°) and of the phase differences, respectively, the phase shift assembly thus provides a solution, which can be adapted to the down-tilt angles required by the operator (i.e., incrementally adjusting a limited number of down-tilt angles, e.g., 2°, 7°, and 14°) by accordingly providing the defined pairs of strip lines of the phase switcher. Thereby, a very compact phase shift assembly can be provided. And since the pairs of strip lines are applied to the phase switcher permanently and in a defined manner for the respective phase differences, no further moving parts or elements have to be used for defining the respective phase difference; that is, by moving the phase switcher to the at least two positions only, the defined phase difference can be precisely set. As such, the required pre-defined down-tilts of an antenna can be easily set as well as the ease of assembly is improved.

In an implementation form of the first aspect, the at least two pairs of strip lines comprise a first pair of strip lines and a second pair of strip lines, wherein the phase switcher is configured to be moved at least between a first position, in which the first pair of strip lines connects the first pair of dipole strip lines with the second pair of dipole strip lines for effecting a first phase difference between the first dipole element and the second dipole element, and a second position, in which the second pair of strip lines connects the first pair of dipole strip lines with the second pair of dipole strip lines for effecting a second phase difference between the first dipole element and the second dipole element. In an implementation form of the first aspect, the at least two pairs of strip lines comprise a third pair of strip lines, and wherein the phase switcher is configured to be moved among the first, the second and a third position, wherein in the third position the third pair of strip lines connects the first pair of dipole strip lines with the second pair of dipole strip lines for effecting a third phase difference between the first dipole element and the second dipole element. Thus, with only one phase switcher three phase differences can be easily and precisely set, thereby enhancing the functionality of the phase shift assembly in a very compact manner.

In an implementation form of the first aspect, the phase switcher is movable among the first, the second, the third and a fourth position, wherein in the fourth position a fourth pair of strip lines connects the first pair of dipole strip lines with the second pair of dipole strip lines for effecting a fourth phase difference between the first dipole element and the second dipole element. This even further enhances the functionality of the phase shift assembly in a very compact manner.

The phase shift assembly may comprise a rotation axis, wherein the phase switcher is pivotable around the rotation axis for moving the phase switcher to the at least two positions, preferably between the first and the second position, and more preferably among the first, the second and the third position, and even more preferably among the first, the second, the third and the fourth position. This is particularly advantageous for a compact layout of the phase shift assembly.

In an implementation form of the first aspect, the phase switcher comprises a fixing area, in particular a hole, for fixing the phase switcher to an actuator by frictional and/or form fit for moving the phase switcher. By way of the actuator, the phase switcher can be accordingly moved between or among the positions. The frictional and/or form fit facilitates an easy assembly of the phase switcher and the actuator.

For a particularly compact arrangement of the at least two pairs of strip lines, the at least two pairs of strip lines are preferably evenly distributed around the rotation axis. In an implementation form of the first aspect, the at least two pairs of strip lines are adapted to connect the first pair of dipole strip lines with the second pair of dipole strip lines indirectly or directly, preferably by touching. Direct connection or touching is particularly advantageous in a TDD (time division duplex) mode and is relatively easy to realize. An indirect connection is particularly advantageous for an FDD (frequency division duplex) mode. Indirect connection may be provided by overlapping the strip lines (RF lines) to each other close enough but without a direct touching such that the (RF) signals can be transmitted between them. Additionally or alternatively, a very thick dielectric film is introduced between the strip lines for indirectly connecting these strip lines with each other.

The at least two pairs of strip lines may have substantially the same width.

Each pair of strip lines of the at least two pairs of strip lines may have a different length for effecting a different phase difference, e.g., the first and the second phase difference and, preferably, for effecting also the third phase difference and, more preferably, for effecting also the fourth phase difference. In other words, the respective phase difference is effected by lengthening the physical path for the respective emitted radio wave by accordingly moving the phase switcher.

The lengths of the strip lines of the second pair of strip lines may be longer than the lengths of the strip lines of the first pair of strip lines, wherein, preferably, the lengths of the strip lines of the third pair of strip lines are longer than the lengths of the strip lines of the second pair of strip lines, and wherein, more preferably, the lengths of the strip lines of the fourth pair of strip lines are longer than the lengths of the strip lines of the third pair of strip lines, such that the first, second, third and fourth phase difference, respectively, can be effected. Thus, the respective phase differences are easily effected.

When viewed in a top view of the phase switcher, each strip line of the second pair of strip lines, and preferably of the third pair of strip lines, and more preferably of the fourth pair of strip lines, may have at least two extending directions for having the respective longer length. Thus, the respective longer pair of strip lines can be easily applied to the phase switcher.

In an implementation form of the first aspect, each strip line of the at least two pairs of strip lines comprises defined end portions for connecting the respective strip line with the first pair and the second pair of dipole strip lines, respectively, wherein, preferably, each of the end portions has a larger width than the remaining portion of the respective strip line. Therefore, a secure connection of the pairs of strip lines with the pairs of dipole strip lines can be ensured, e.g., for compensating tolerances between the phase switcher and the dipole strip lines.

In an implementation form of the first aspect, the end portions of each strip line are equally spaced from one another. This is particularly advantageous for an easy application of the strip lines having different lengths, since after the application of a first strip line, the distance between the end portions does not need to be adjusted, when a second strip line, which is shorter or longer than the first strip line, is to be applied.

The at least two pairs of strip lines are preferably arranged in a square (in particular in the case of only two pairs of strip lines), a (equal) hexagon (in particular in the case of only three pairs of strip lines) or an (equal) octagon (in particular in the case of only four pairs of strip lines). These arrangements of the pairs of strip lines are particularly advantageous for an effective spatial arrangement of the strip lines.

The phase shift assembly may further comprise an actuator for moving the phase switcher to the at least two positions, preferably, between the first and the second position, and, more preferably, among the first, the second and the third position, and, even more preferably, among the first, the second, the third and the fourth position.

According to a second aspect of the invention, an antenna (element) comprises a phase shift assembly as described herein above, a first dipole element coupled to the first pair of dipole strip lines, and a second dipole element coupled to the second pair of dipole strip lines. The advantages described herein above with respect to the phase shift assembly apply to the antenna correspondingly. That is, with the phase shift assembly and the so effected phase differences a corresponding number of different down-tilt angles of the beam of the antenna can be effected. Furthermore, the antenna can be made more compact as well as easier to assemble and control.

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

Brief description of drawings

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

Figure 1 is a schematic plan view of an example of an antenna comprising an example of a phase switch assembly;

Figure 2 is a side view of the antenna shown in figure 1 ; and

Figure 3 is a schematic perspective exploded view of the phase switch assembly. Detailed description of embodiments

Examples of embodiments of the invention are described below with reference to the enclosed figures.

Figures 1 and 2 exemplarily show an antenna 100 comprising a plurality of antenna elements 101. The antenna 100 may be a multiple input multiple output (MIMO) antenna. The antenna elements 101 may be evenly distributed over an area, when viewed in a plan view, and/or provided in an array. The antenna 100 may further comprise a reflector R on the backside of the antenna elements 101 for reflecting the radio waves emitted by the antenna elements to the front side of the antenna elements 101 , i.e. in the main radio wave emitting direction of the antenna 100.

Each antenna element 101 comprises two ports 102 for coupling or connecting to a feed network 103 (feed line), e.g., a TRX board. Each Antenna element 101 can work independently or dependently with respect to the respective other antenna elements 101. The down-tilt beam of the antenna 100 results by the beams of all the antenna elements 101 in the vertical column. In order to effect a defined down-tilt angle, the phase delay or phase difference within each of the antenna elements 101 is controlled. The phase delay between the antenna elements 101 is controlled by the whole system, which uses as input the related array pitches d2 and the phase differences of the respective antenna elements 101. As such, the system can control the antenna elements 101 such that each antenna element 101 has the same phase difference for realizing the desired angle of the resulting beam.

Each antenna element 101 comprises a first dipole element 104 and a second dipole element 105. Furthermore, each antenna element 101 comprises a phase switch assembly 1 for coupling or connecting the feed network 103 or ports 102 to the dipole elements 104 and 105. The phase switch assembly 1 may be indirectly connected to the feed network 103, in particular due to PIM (passive intermodulation) consideration, i.e. in particular for reducing the generation of interfering signals caused by nonlinearities in the mechanical components. This is particularly advantageous when using the phase switch assembly 1 in an FDD (frequency division duplex) antenna. When using the phase switch assembly 1 in a TDD (time division duplex) antenna, the phase switch assembly 1 may be directly connected to the feed network 103, which is easier to realize.

Figure 3 shows the phase shift assembly 1 in more detail. The phase shift assembly 1 comprises a first pair of strip lines (referred to herein as the first pair of dipole strip lines) 2 for coupling the first dipole element 104 to the feed network 103. More specifically, the first pair of dipole strip lines 2 comprises two connection ports 21 , which can couple with the ports 102 of the feed network 103, and two or four connection ports 22, which can couple to the first dipole element 104. The phase shift assembly 1 further comprises a second pair of strip lines (referred to herein as the second pair of dipole strip lines) 3 for coupling the second dipole element 105 to the feed network 103, e.g., at least by two or four connection ports 31.

The pairs of dipole strip lines 2, 3 are provided on a single plate 4. In other examples, the pairs of dipole strip lines 2, 3 may also be provided on separate plates. The plate 4 has preferably a thin and/or flat structure. The plate 4 may have a rectangular shape, when viewed in a plan view of the plate 4. In other examples, the plate 4 may also have different shapes, e.g., a circular, polygonal or any other suitable shape.

The phase shift assembly 1 further comprises a phase switcher 5 comprising (only) two pairs of strip lines 51 and 52. The present invention is, however, not limited to a particular number of pairs of strip lines. That is, the phase switcher 5 may also comprise three, four or more pairs of strip lines.

The phase switcher 5 may be formed as a (single) thin and/or flat plate, which preferably has a shape, which corresponds to the arrangement of the at least two pairs of strip lines 51 , 52. For example, the phase switcher 5 may have a polygonal shape, preferably a substantially rectangular or square shape, when viewed in a top view of the phase switcher 5.

The phase switcher 5 of the phase shift assembly 1 shown in figure 3 is movable or configured to be moved (only) to at least two positions, e.g., between a first position and a second position, in which for each position, a pair of strip lines of the at least two pairs of strip lines 51 , 52 connects the first pair of dipole strip lines 2 with the second pair of dipole strip lines 3 for effecting a phase difference between the first dipole element 104 and the second dipole element 105.

In the first position, the first pair of strip lines 51 connects the first pair of dipole strip lines 2 with the second pair of dipole strip lines 3. In this first position, the lengths of the strip lines 51 effect - due to the physical length of the strip lines 51 - a first phase difference between the first dipole element 104 and the second dipole element 105. That is, the lengths of the strip lines 51 effect a length for the signal of the second dipole element 105, which is longer than the length for the signal of the first dipole element 104, thereby delaying the signal for the second dipole element 105. More specifically, the signal of the dipole element 104 travels only the physical path defined by the first pair of dipole strip lines 2, whereas the signal of the dipole element 105 travels the physical path defined by at least a part of the first pair of dipole strip lines 2, the first pair of strip lines 51 and the second pair of dipole strip lines 3. A phase difference is thus effected between the radio waves emitted by the dipole elements 104, 105. A corresponding angle of the beam of the antenna 100 can thus be set.

In the second position, the second pair of strip lines 52 connects the first pair of dipole strip lines 2 with the second pair of dipole strip lines 3 for effecting a second phase difference between the first dipole element 104 and the second dipole element 105. As can be seen in figure 3, the lengths of the second pair of strip lines 52 are longer than the lengths of the first pair of strip lines 51. Thereby, the second pair of strip lines 52 effects a second phase difference, which is greater than the phase difference effected by the first pair of strip lines 51. More specifically, the signal of the dipole element 104 travels only the physical path defined by the first pair of dipole strip lines 2, whereas the signal of the dipole element 105 travels the physical path defined by at least a part of the first pair of dipole strip lines 2, the second pair of strip lines 52 and the second pair of dipole strip lines 3. Since the second pair of strip lines 52 is longer than the first pair of strip lines 51 , the physical path of the signal of the second dipole element 105 in the second position is longer than the physical path of the signal of the second dipole element 105 in the first position. In the second position, the signal of the second dipole element 105 thus travels a longer path than in the first position, thereby further delaying said signal and, thus, effecting the second phase difference.

The longer lengths of the second pair of strip lines 52 are effected by providing the second pair of strip lines 52 such that each of the strip lines of the pair 52 has two extending directions, when viewed in a top/plan view of the phase switcher 5. In the example of figure 3, each of the strip lines of the pair 52 extends in a rectangular manner. In other examples, each of the strip lines of the pair 52 may also extent in a polygonal manner, e.g., in a zigzag manner. In contrast, each of the strip lines of the pair 51 extents substantially only in one extending direction, namely in a straight manner and has thus a shorter length than each of the strip lines of the pair 52. In the second position of the phase switcher 5, a corresponding angle of the beam of the antenna 100 can thus be easily set, which is different from the angle set in the first position.

For moving the phase switcher 5 between the first and the second position, the phase switcher 5 preferably comprises a rotation axis, wherein the phase switcher 5 is pivotable around the rotation axis. Thus, by rotating the phase switcher 5 of the embodiment in figure 3 with 90° around the rotation axis, the first position and the second position, respectively, can be reached. In other examples, the phase switcher may be additionally or alternatively also be translationally movable to move the phase switcher 5 between the first position and second position. In the example shown in figure 3, the phase switcher 5 comprises a fixing area 53 in the form of a hole for fixing the phase switcher 5 to an actuator by a form fit. Additionally or alternatively, also a frictional fit, e.g., with suitable fastening means, may be provided for fixing the actuator to the fixing area 53. As such, a rotating movement of the actuator will correspondingly rotate the phase switcher 5 to move the phase switcher 5 between the two positions by way of the connection provided by the fixing area 53. Preferably, the actuator passes through a hole 41 of the plate 4 for mating with the fixing area 53. The phase shift assembly 1 may further comprise a control unit (not shown) for accordingly controlling the actuator for moving the phase switcher 5 to, between or among the positions.

The pairs of strip lines 51 , 52 are evenly distributed around the rotation axis and the fixing area 53, respectively, of the phase switcher 5 and arranged in the form of a square. The pairs of strip lines 51 , 52 may also be provided according to different shapes, e.g., according to a parallelogram or any other polygonal shape. A preferred arrangement for three pairs of strip lines is a (equal) hexagon. A preferred arrangement for four pairs of strip lines is an (equal) octagon. As such, the positions for connecting the pairs of dipole strip lines 2, 3 with one another by the pairs 51 , 52 can be easily reached.

In the example shown in figure 3, the at least two pairs of strip lines 51 , 52 may connect the first pair of dipole strip lines 2 with the second pair of dipole strip lines 3 indirectly or directly, preferably by touching.

Each strip line of the pairs of strip lines 51 , 52 comprises defined end portions 51 1 , 521 , which are provided for connecting the respective strip line with the pairs of dipole strip lines 2, 3, respectively. For connecting the respective strip line with the pairs of dipole strip lines 2, 3, the dipole strip lines 2, 3 may comprise connection or end portions 23, 32, respectively, which preferably correspond in size and/or shape to the end portions 51 1 , 521 . In the example shown in figure 3, the end portions 51 1 , 521 comprise a substantially rectangular form for having a larger width than the remaining portion of the respective strip line. However, the end portions 51 1 , 521 may also comprise any other defined shape for having a larger width than the remaining portion of the respective strip line. Preferably, the end portions 511 , 521 are identically shaped.

As can be seen in figure 3, the end portions 51 1 , 521 of each strip line of the pairs 51 , 52 are equally spaced from one another, even though the strip lines of the second pair 52 are longer than the strip lines of the first pair 51. As such, the phase switcher 5 can be made compact. The pairs of strip lines 51 , 52 have substantially the same width. The width of the strip lines may be, however, also different. It should be clear to a skilled person that the invention shown in the figures is only a preferred embodiment, but that, however, also other designs of a phase shift assembly 1 having more or less than two pairs of strip lines 51 , 52 can be used. In particular, the phase shift assembly 1 may comprise a phase switcher 5 comprising more than two pairs of strip lines, i.e. any number of pairs of strip lines, (e.g., three, four, five, six, seven, eight, nine or more pairs of strip lines) for effecting more than two defined phase differences (e.g., three, four, five, six, seven, eight, nine or more phase differences). Correspondingly, the phase switcher 5 may be configured to be moved among more than two positions, e.g., among three, four, five, six, seven, eight, nine or more positions, for correspondingly effecting the more than two phase differences.

The present invention 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 invention, 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.