Technical Field

The present disclosure relates to an actuator for a phase shifter of an antenna, and a phase shifter assembly comprising such an actuator.

Background

A conventional antenna may have a plurality of antenna elements. The antenna can change the angle of the emitted beam of radio waves by delaying the radio waves emitted by the antenna elements so that each antenna element emits its wave front later (or earlier) than the one below it. This causes the resulting emitted beam of radio waves to be directed at a desired angle. The delaying of the respective radio wave (phase shift) is effected by a phase shifter, which, for example, changes the physical path of the respective radio wave, thereby delaying the radio wave and, thus, effecting a phase shift.

A conventional actuator may be connected to the phase shifter so that by a rotational or linear movement of the actuator the phase shifter is actuated for effecting the phase shift. One or more electric motors may act as actuator to provide the consecutive movement (e.g., rotary) and driving power. For using the movement and driving power of the one or more electric motors for actuating the phase shifter, it is known to provide a transmission device, which connects the electric motor(s) to the phase shifter for transmitting the power and motion/torque to the phase shifter so that the phase shifter can be accordingly actuated. For example, rigid bars or flexible shafts are used to transmit the force/torque and speed (rotational or linear speed) to drive the phase shifter. A control board controls the motor and the actuator for managing the power supply strategies.

Disadvantages of the conventional actuators are the high costs of the electrical motor and the transmission device. In particular, the transmission device usually requires a long transmission chain for accordingly transmitting the power to the phase shifter. The long transmission chain, however, causes much loss in transmission efficiency. Furthermore, the long transmission chain results in an accumulation of dimensional tolerances and, thus, causes poor transmission precision. Besides that, the electrical motor and the transmission device require a lot of space, thereby also limiting the layout design of the antenna, in which the phase shifter is to be used.

Summary

Therefore, the embodiments of the invention aims to provide an actuator for a phase shifter and a phase shifter assembly comprising such an actuator, which overcome the afore mentioned disadvantages. In particular, it is an objective to provide a more compact, more efficient and more precise actuator for a phase shifter of an antenna.

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 particular embodiments of the invention.

According to a first aspect of the invention, an actuator for a phase shifter of an antenna comprises: a body for being coupled to with a phase shifter, a transmission element coupled to the body, and a shape memory alloy (SMA) wire having a first end and a second end. The transmission element is in contact (e.g., in direct contact) with a section of the wire between the first end and the second end of the wire such that a shortening of the wire moves the transmission element and thereby moves the body to actuate the phase shifter.

Shortening of the shape memory alloy wire is usually effected by heating the shape memory alloy to the transformation or transition temperature of the shape memory alloy; the heating may be effected by an electrical power source, which heats the wire by resistance heating. At the transformation or transition temperature, the shape memory alloy changes from the martensitic to the austenitic state, thereby effecting the change of the length (e.g., shortening) of the wire.

As such, the shape memory alloy wire can be precisely shortened without the need of a rotating or linear moving electric motor. Due to the omission of such motors, the transmission chain between the power input and the phase shifter or any other device actuated by the actuator can be significantly reduced or even omitted. Replacing the motor by the shape memory alloy wire reduces also the costs, since the shape memory alloy wire has a significantly simpler structure, e.g., in the form of a filament. And since the shape memory alloy wire connected to the transmission element substantially extends in only one plane, the actuator can be made compact.

Furthermore, the connection of the transmission element to a section or position of the wire between the first end and the second end - or, in other words, no direct connection between the ends of the wire and the body - effects an easy assembly of the actuator, since the shape memory alloy wire only needs to be wound around the transmission element. Furthermore, since the transmission element is not connected to the ends of the wire, both ends can be connected to a fixed position of the actuator, thereby improving the precision of the actuator as well as the ease of assembly. Besides that, both ends of the wire can be used for effecting a shortening of the wire, thereby easily increasing the force exerted by the wire. This is particularly advantageous for a precise control by means of the wire.

Particularly, the body is rotatable about a rotation axis. The shortening of the wire moves the transmission element and thereby rotates the body to actuate the phase shifter. This is particularly advantageous for a compact layout of the actuator.

Particularly, the shortening of the wire moves the transmission element and thereby moves the body in a forward sense to actuate the phase shifter. The actuator may comprise a ratchet mechanism for preventing the body from moving in a backward sense during a lengthening of the wire. In other words, the body may be part of a ratchet mechanism. The ratchet mechanism is configured to prevent a movement of the body during lengthening of the wire. As such, by moving backward and forward of the transmission element (i.e. a circulating mode) by shortening and lengthening of the wire, respectively, the body can be moved in any desired position for actuating the phase shifter, in particular by only requiring a relatively short path for displacing the transmission mechanism.

The ratchet mechanism may comprise a gear and a pawl. The body comprises the gear and the transmission element comprises the pawl for connecting the transmission element with the body. As such, the whole range of motion of the transmission element can be used for moving the body, thereby effecting a more effective transmission of the movement from the transmission element to the body. For example, in case the body is a rotatable body, the pawl can remain connected to the circumference of the body during rotation of the body. For a particularly compact arrangement of the pawl with respect to the body, the pawl may be rotatable about a rotation axis being particularly parallel to the rotation axis of the body.

Particularly, the transmission element comprises a pivotable lever. The pivotable lever comprises the pawl. As such, a movement of the transmission element can be transferred to the body via the lever for moving the body for actuating the phase shifter.

Particularly, the transmission element comprises a biasing element for biasing the lever and the pawl, respectively, towards the body. Thus, the biasing element effects that the pawl is securely connected to the body during movement of the transmission element and the body. The biasing element may be a spring, in particular a spring sheet.

The ratchet mechanism may comprise a (further) pawl for engaging with the body for preventing a movement of the body during a lengthening of the wire.

The wire may be wound around the transmission element. Thereby, the transmission of the movement effected by shortening of the wire is effectively transmitted to the body. Particularly, the wire is wound around the transmission element at a contact angle (or wrap angle or arc of contact) of a contact area between the transmission element and the wire from 1° to 225°, more particularly from 1° to 180°. In other words, the wire may be wound around the transmission element such that the end sections of the wire, i.e. those sections of the wire, which do not contact the transmission element at the contact area, are parallel to one another or form an angle from 180° to 1°.

Particularly, the transmission element is movable for moving the body for actuating the phase shifter such that during shortening of the wire a contact angle of a contact area between the transmission element and the wire changes. As such, the (original) length of the wire can be reduced. Alternatively, said angle may also be constant during shortening of the wire, which is also advantageous for a compact layout of the actuator. Shortening of the wire may shift the transmission element and thereby move the transmission element to actuate the phase shifter. Particularly, the transmission element is translationally movable for moving the body for actuating the phase shifter. Thus, the actuator can be made compact, since the transmission element is restricted to a linear or shifting movement only. Particularly, the transmission element comprises a slider for translationally moving the transmission element. Therefore, an easy assembly is achieved, since the slider can be pre assembled with other components of the transmission element and/or the actuator, e.g., with the biasing elements used in connection with the transmission element. The actuator may comprise a guiding element for confining the motion of the transmission element to one translational direction. The guiding element may, for example, be a tube or a rail.

Particularly, shortening of the wire rotates the transmission element about a rotation axis and thereby moves the body to actuate the phase shifter. In other words, the transmission element may be rotatable about said rotation axis for moving the body for actuating the phase shifter. The rotation axis of the transmission element may be the rotation axis of the body. Thus, the actuator can be made compact. Alternatively or additionally, the transmission element may be provided eccentrically with respect to rotation axis of the body. As such, the transmission element can be reduced in size, e.g., by providing the transmission element as a protrusion being eccentrically provided with respect to the body.

The actuator may comprise a biasing element for effecting an opposing force against the transmission element during shortening of the wire, such that during lengthening of the wire the opposing force moves the transmission element in a direction, which is opposite to the direction for moving the transmission element for moving the body for actuating the phase shifter. In other words, the biasing element is configured to return the transmission element to its original position. As such, even on a short path for (linearly or rotationally) moving the transmission element, the body can be moved at any desired position for accordingly actuating the phase shifter.

The ends of the wire may be fixed, in particular with respect to the actuator. For example, the ends of the wire may comprise an integrally or separately formed protrusion such as a ring or a flange for engaging with a fixed part of the actuator. Thus, the actuator can be easily assembled. The ends of the wire may be connectable to a power source for supplying electrical power to the wire for resistance heating of the wire for shortening the wire. For example, the ends of the wire are designed as a plug. The power source may in turn be connected to a control unit so that the control unit can precisely set the defined length for shortening of the wire and/or the speed of shortening the wire.

The actuator may comprise a housing for housing at least the body, the transmission element and the shape memory alloy wire. Since the body, transmission element and shape memory alloy wire can be effectively arranged to one another, the housing can be made simply and compact.

According to a further aspect of the invention, a phase shifter assembly for an antenna comprises an actuator as described herein above and a phase shifter, which is coupled to or directly connected with the body for actuating the phase shifter by the actuator. As such, any transmission device between the actuator and the phase shifter other than the direct connection between them can be omitted because of the precisely controllable actuator. The direct connection may be provided by a form fit and/or a frictional fit.

Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

Figure 1 is a schematic cross-sectional view of an actuator according to a first embodiment;

Figure 2 is a schematic perspective exploded view of a phase shift assembly according to an embodiment comprising the actuator of figure 1;

Figure 3 is a schematic perspective exploded view of a part of the actuator shown in figure 1; Figures 4A-4F are schematic cross-sectional views of the actuator shown in figure 1, which show the body and the transmission element in different positions, respectively, for actuating the phase shifter;

Figure 5 is a schematic side view of an actuator according to a second embodiment; and

Figure 6 is a side view of figure 5, wherein part of the actuator has been omitted for better illustrating the transmission element.

Detailed Description

The embodiments of the invention are described exemplarily with reference to the enclosed figures.

In the following, two embodiments of the actuator according to the present invention are exemplarily described. Same features are indicated with the same reference signs.

The actuator may be used for shifting the phase of an antenna element in an antenna. For example, the phase shifter is a device capable of changing the physical path of the emitted radio wave, thereby delaying the radio wave and thus shifting the phase of the respective radio wave. The actuator may be used to actuate the phase shifter so that the phase shifter shifts the phase of the radio wave, e.g., by changing the physical path of the radio wave.

Figure 1 exemplarily shows an actuator 1 according to a first embodiment. The actuator 1 comprises a body 2 for being coupled to a phase shifter 50 (e.g., directly connectable with a phase shifter 50) and which is movable for actuating the phase shifter 50. An exemplary phase shift assembly 100 comprising the actuator 1 and the phase shifter 50 is shown in figure 2. As can be seen in figure 2, the body 2 may be for being coupled to or directly connectable to the phase shifter 50 by a form fit, e.g., a protrusion 51 on the side of the phase shifter 50, which has a defined shape (angular, polygonal, rectangular, square, etc.), and which can mate with a corresponding structure or hole on the side of the actuator 1, e.g., integrally formed with the body 2. By way of the connection between the body 2 and the phase shifter 50, the movement of the body 2 can be transmitted to the phase shifter 50, thereby effecting an actuation of the phase shifter 50.

In the embodiment shown in figure 1, the body 2 is rotatable about a rotation axis for moving the body 2 for actuating the phase shifter 50. In other embodiments, the body 2 may be also translationally movable for actuating the phase shifter 50. In the phase switch assembly 100 shown in figure 2, the connecting part for connecting to the actuator 1 with the phase shifter 50, e.g., the structure 51, is thus correspondingly movable, i.e. rotatable, in particular about a rotation axis, which is flush with the rotation axis of the body 2. By means of the corresponding moveable structure 51, the phase shifter 50 can thus be actuated.

The actuator 1 further comprises a transmission element 3, which is coupled or connected to the body 2. In the example shown in figure 1, the transmission element 3 is translationally movable for moving the body 2 (in a forward sense) for actuating the phase shifter 50, i.e. in a left and right direction with respect to the figure 1. More specifically, the transmission element 3 comprises a translationally movable slider 4, which connects to the body 2 for moving the body 2. The connection between the transmission element 3 and the body 2 or between the slider 4 and the body 2 may be provided by a pivotable pawl 5, e.g., provided on or integrally formed with a pivotable lever. As such, a movement of the transmission element 3, in particular of the slider 4, can be transferred to the body 2 via the pawl 5 so that the body 2 moves or rotates for actuating the phase shifter 50. Particularly, the pawl 5 is rotatable about a rotation axis. For example, the slider 4 comprises a preferably integrally formed structure such as a protrusion, which connects to the pawl 5 or lever so that the pawl 5 is rotatable about the rotation axis. That is, the rotation axis of the pawl 5 translationally moves in accordance with the translational movement of the slider 4. As can be seen in figure 1, the rotation axis of the pawl 5 is particularly parallel to the rotation axis of the body 2, i.e. both rotation axes are perpendicular to the plane of figure 1.

The transmission element 3 further comprises a biasing element 6 in the form of a spring sheet for biasing the lever or pawl 5 towards the body 2. In other examples, the biasing element 6 is a spring or any other biasing element capable of biasing the lever or pawl 5 towards the body 2. By means of the biasing element 6, it can be ensured that the pawl 5 remains connected or engaged with the rotating body 2, while the transmission element 3 or the slider 4 translationally moves.

The actuator 1 further comprises a shape memory alloy wire 7, which extends between a first end 71 and a second end 72 of the wire 7. The wire 7 may have the form of a filament. The shape memory alloy of the wire 7 may be nickel titanium alloy or nitinol. The transmission element 3, e.g., a structure 8, in particular a protrusion of the slider 4 having, for example, a circular shape, is directly connected to a position or section of the wire 7, which is between the first end 71 and the second end 72. As such, a shortening of the wire 7 effects that the transmission element 3 is moved, thereby also moving the body 2 for actuating the phase shifter 50. Shortening of the wire 7 may be effected by connecting the ends 71, 72 to a power source (not shown) so that the power source supplies electrical power to the wire 7, thereby shortening the wire 7 by resistance heating and due to the material properties of the shape memory alloy. For example, the ends 71, 72 are designed as plugs for easily connecting the wire 7 to the power source.

In the embodiment exemplarily shown in figure 1, the wire 7 is wound around the transmission element 3, in particular around the structure 8, so that a contact angle of a contact area between the transmission element 3, i.e. the structure 8, and the wire 7 is formed. In the embodiment shown in figure 1, the contact angle is 180°. As such, those parts of the wire 7, which are not in contact with the contact area, extend substantially parallel to one another or horizontally, when viewed with respect to figure 1. In other examples, the contact angle range is more than 180°, e.g., up to 225° °, or less than 180°, e.g., between 135° and 180°. In those examples, the parts of the wire 7 being not in contact with the contact area are thus provided at an angle between one another.

According to the actuator 1 of the first embodiment, a movement of the transmission element 3 for moving the body 2 effects, in particular due to the attachment/connection of the wire 7 to the apparatus 1 , that during shortening of the wire 7 the contact angle of the contact area between the transmission element 3 and the wire 7 is constant, i.e. does not change. That is, during the whole range of motion of the transmission element 3 due to shortening/lengthening of the wire 7, the end regions comprising the ends 71, 72, respectively (the parts of the wire 7 being not in contact with the contact area), remain substantially parallel. The wire 7 may be fixedly connected with respect to the apparatus 1. More specifically, the ends 71, 72 of the wire 7 may be fixed with respect to the apparatus 1 by comprising structures 73, 74, respectively. For example, each of the structures 73, 74 comprises a flange or any other protrusion, which can be connected to (a fixed part of) the apparatus 1 by a form fit.

In order to ensure that the transmission element 3 returns to its original position during lengthening of the wire 7, the actuator 1 may comprise a biasing element 9. The biasing element 9 is provided such that an opposing force is effected against the transmission element 3 during shortening of the wire 7; during lengthening of the wire 7, the opposing force thus moves the transmission element 3 in a direction, which is opposite to the direction for moving the transmission element 3 for moving the body 2 for actuating the phase shifter 50. With respect to figure 1, during shortening of the wire 7 and, thus, moving of the transmission element 3 to the left, the biasing element 9 effects a force to the right, thereby effecting that the transmission element 3 is moved to the right as soon as the wire 7 begins to lengthen. The biasing element 9 may be an elastic element such as a coil spring, which is with one end connected with a fixed part of the apparatus 1 and with the other end connected to the transmission element 3, in particular to the slider 4.

As can be seen in figure 1, the body 2 is particularly part of a ratchet mechanism 10. The ratchet mechanism 10 is configured to prevent a movement in a backward sense of the body 2 during lengthening of the wire 7. With reference to figure 1, the ratchet mechanism 10 is thus configured to prevent a backward or clockwise rotation of the body 2 so that the body 2 can - due to the configuration of the ratchet mechanism 10 -only move in the forward or anti clockwise direction. With this configuration, a back and forth movement of the transmission element 3, i.e. a circulating movement of the transmission element 3, along a relatively short path can effect a movement/rotation of the body 2 with any desired displacement/rotation. Thus, a compact actuator 1 can be provided for effectively actuating the phase shifter 50.

For providing the desired configuration of the ratchet mechanism 10, the ratchet mechanism 10 may comprise a pawl 11, which engages with the body 2 for preventing a movement/rotation of the body 2 during a lengthening of the wire 7. Such a configuration is similar to the configuration of other conventional ratchet mechanisms art. For example, the ratchet mechanism 10 further comprises a biasing element 12, which biases the pawl 11 towards the body 2, thereby more effectively preventing a movement/rotation of the body 2 during a lengthening of the wire 7.

The body 2 may be designed as a gear. As such the pawl 5 and/or the lever/pawl 11 can effectively engage with the body 2 for effectively moving the body 2 by the pawl 5 and/or for effectively preventing a movement of the body 2 during lengthening of the wire 7 by the pawl 11. That is, the teeth of the body 2 may be designed as comprising asymmetric tooth flanks permitting a movement in one direction (anti-clockwise direction) and blocking a movement in the opposite direction (clockwise direction).

The apparatus 1 may further comprise a housing for housing at least the body 2, the transmission element 3, and the shape memory alloy wire 7, and, Particularly, all other components which were described herein above. The housing may be composed of a single housing part or of a plurality of housing parts, e.g., two housing parts. Figure 3 exemplarily shows a housing part 13 of the housing. The housing part 13 may comprise structures for translationally guiding the transmission element 3 and slider 4, respectively. The housing/housing part 13 may comprise a stopper 14, e.g., a structure such as a protrusion being integrally formed with the housing part 13, for preventing the transmission mechanism 3 or the slider 4 from falling out of the apparatus 1, in particular from moving further (to the right) than its original position. The housing 13 may also comprise a structure 15, e.g., a recess, which is correspondingly formed to the ends 71, 72, particularly the structures 73, 74, for fixedly connecting the ends 71, 72 to the apparatus 1, e.g., by a form fit. The plurality, in particular two housing parts of the housing may be connected to one another by a snap fit or any other suitable fastening elements.

The actuator 1 may comprise a guiding element for confining the motion of the transmission element 3 to one translational direction. The guiding element may, for example, be a tube or a rail. The guiding element may be integrally formed with the housing, e.g., with the housing part 13.

With reference to the figures 4A to 4F, the actuation by the wire 7, transmission element 3, and body 2 is explained exemplarily in more detail. Figure 4A shows the apparatus 1 in a state, in which the wire 7 is in its original or originally long state. Consequently, the transmission element 3, more specifically the slider 4, is at its original position, which is the position xo. This in particular for the reason, that the biasing element 9 has returned the slider 4 2 towards its original position x ₀ , which is was reached as soon as the slider 4 came in contact with the stopper 14.

As soon as the wire 7 begins to shorten, e.g., by resistant heating as described above, the shortening or shrinkage of the wire 7 effects a movement of the transmission element 3/slider 4 amongst others to the positions xi, X2, X3, i.e. to the left with reference to figures 4A to 4F. These positions xi, X2, X3 as well as the so caused movement of the transmission element 3 are shown in figures 4B, 4C, and 4D, respectively. Since the transmission element 3, in particular the lever 5, is connected to the body 2, the body 2 will move accordingly (in the figures in an anti-clockwise manner), i.e. with the rotations n, n, n, respectively. A direct connection between the body 2 and the phase shifter 50 will thus accordingly actuate the phase shifter 50. For example, the different rotations n, G2, G3 of the body 2 correspond to different phase shifts effected by the phase shifter 50.

Figure 4D exemplarily shows the state of the actuator 1, in which a final position of the transmission element 3/slider 4 is reached, e.g., because the wire 7 cannot be further shortened. Thus, the wire 7 will be accordingly controlled, e.g., the power (currency and/or voltage) for resistance heating of the wire 7 will be lowered or cut off, for effecting that the wire 7 lengthens. Consequently, since the biasing element 9 is loaded due to the movement of the transmission element 3 due to the shortening of the wire 7, the biasing element 9 will push the transmission element 3 back to its original position xo (see figures 4E and 4F). Since the ratchet mechanism 10 is accordingly configured, the returning of the transmission element 3 to its original position xo will have no effect on the effected displacement/rotation of the body 2. That is, the body 2 will remain at the rotation n during lengthening of the wire 7 and, thus, during returning of the transmission device 3 to its original position xo.

When the transmission element 3 has reached the original position xo, the above process can be repeated, e.g., such that the transmission element 3 moves back and forth (i.e. a circulating movement), thereby effecting a displacement/rotation (angel) of the body 2 going further than the rotation G3. Accordingly, the actuator 1 can substitute an electric motor for effecting the respective movements for the actuation of the phase shifter 50.

Figures 5 and 6 exemplarily show an actuator according to a second embodiment. Unless otherwise stated in the following, what was said with respect to the first embodiment applies likewise or analogous to the second embodiment; same features have the same reference signs.

The actuator 1’ according to the second embodiment differs from the actuator 1 according to the first embodiment in particular in the feature of the transmission element, and the way the wire 7 is connected to the transmission element. More specifically, the apparatus 1’ comprises a transmission element 3’, which is movable for moving the body 2 such that during shortening of the wire 7 the contact angle of a contact area between the transmission element 3’ and the wire 7 changes. With reference to figure 6, shortening of the wire 7 will effect that the contact angle of the contact area between the transmission element 3’ and the wire 7 decreases. For example, in the longest state of the wire 7, the contact angle may be in the range from 45° to 90°, wherein in the shortest state of the wire 7, i.e., when with reference to figure 6 the wire 7 extents substantially horizontally only, said contact angle is in the range from 0° to 2°.

In the embodiment of the actuator 1’ shown in figures 5 and 6, the transmission element 3’ is rotatable about a rotation axis, in particular rotatable about the rotation axis of the body 2. As such, a compact actuator G can be provided. In particular, the transmission element 3’ is connected to the body 2 by the pawl 5 as described above with respect to the first embodiment. The transmission element 3’ may be eccentrically provided with respect to the rotation axis of the body 2, i.e. the transmission element 3’ may comprise a structure 4’, e.g., in the form of a protrusion, which is eccentrically provided with respect to the rotation axis of the body 2 when viewed in a side view of the actuator G. As such, the wire 7 is wound around the structure 4’.

In use of the actuator 1’ and when viewed with reference to figure 6, shortening of the wire 7 will effect that the structure 4’ moves upward. The upward movement of the structure 4’ will effect a rotation of the structure 4’ and transmission element 3’, thereby also effecting a rotation of the body 2 by the connection between the transmission element 3’ and the body 2, e.g., by way of the lever 5. Accordingly, the body 2 will move/rotate about a corresponding rotation n. During lengthening of the wire 7, the biasing element 9, which was loaded during shortening of the wire 7, will return the transmission element 3’ and structure 4’ to its original position. Due to the configuration of the ratchet mechanism 10 as described previously, the body 2 will remain at the rotation/displacement n.

The above described process for moving the transmission element 3’ by shortening and lengthening of the wire 7 can be repeated, in particular such that a back and forth movement of the transmission device 3’ (i.e. a circulating movement) is effected. Thereby, the body 2 can be rotated or displaced to a rotation further than n.

It should be clear to a skilled person that the embodiments shown in the figures are only exemplary embodiments, but that, however, also other designs of the actuator 1, G can be used. In particular, the actuator 1 is not limited to be used in a phase shifter or an antenna. For example, the actuator 1, G may be used for any device, which requires a compact layout and a precise actuation.