Patent Publication Number: US-2023155287-A1

Title: Phase shifter, remote electrical tilt system and base station antenna

Description:
RELATED APPLICATIONS 
     The present application is a continuation of and claims priority to U.S. Pat. Application No. 17/369,221, filed Jul. 7, 2021, now U.S. Pat. No. 11,552,396, which claims priority from and the benefit of Chinese Application No. 202010725727.1, filed Jul. 24, 2020, the disclosure of each of which is hereby incorporated herein by reference in full. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure generally relates to the field of base station antennas, and more particularly, to a phase shifter, a remote electrical tilt system with a phase shifter, and a base station antenna with a remote electrical tilt system. 
     BACKGROUND OF THE INVENTION 
     Currently, the remote electrical tilt antenna (RET antenna) is widely used as a base station antenna in cellular communication systems. Before introducing the RET antenna, when it was necessary to adjust the coverage area of the traditional base station antenna, the technician had to climb the antenna tower with the antenna installed and manually adjust the antenna’s pointing angle. Generally, the coverage area of the antenna is adjusted by changing the so-called “tilt angle” of the antenna, which is the angle in the elevation plane of the visual axis pointing direction of the antenna beam generated by the antenna. The introduction of the RET antenna allows cellular operators to electrically adjust the tilt angle of the antenna beam by sending control signals to the antenna. 
     The RET antenna further includes a RET system, which allows the cellular operator to dynamically adjust the tilt angle of the antenna beam. The RET system usually includes a drive motor, a transmission mechanism, and a phase shifter for each array of radiating elements. Many modern base station antennas include multiple arrays of radiating elements, and each array usually has associated drive motor, transmission mechanism and phase shifter, which makes the antenna structural arrangement complicated. Therefore, improving the space utilization of the antenna is an urgent problem to be solved. In addition, the stability of the transmission in the RET system should also be improved. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present disclosure is to provide a phase shifter, a remote electrical tilt system with a phase shifter and related base station antennas for overcoming at least one defect in the prior art. 
     The first aspect of the present disclosure is to provide a phase shifter, which comprises: a phase shift circuit board with conductive traces printed thereon; and a slide device with a first tooth section configured to be driven, wherein movement of the first tooth section drives the slide device to slide on the phase shift circuit board. 
     According to the present disclosure, the stability of the transmission of the remote electrical tilt system may be improved and the space utilization of the remote electrical tilt system may be increased. 
     In some embodiments, the first tooth section is configured as a sector gear section. 
     In some embodiments, an arc profile of the sector gear section extends following an arc trajectory of the conductive trace. 
     In some embodiments, the slide device is rotatably mounted on the phase shift circuit board by means of a pivot shaft. 
     In some embodiments, the slide device includes a slider and a slider support, and the slider is supported on the slider support. 
     In some embodiments, the first tooth section is configured on the slider support. 
     In some embodiments, the slider is configured as a slide circuit board, on which a first coupling part coupled to the input port of the phase shift circuit board and a second coupling part coupled to a respective conductive trace are printed. 
     In some embodiments, the phase shift circuit board comprises: an input port which is configured to receive a RF signal; a first output port and a second output port respectively configured to output a corresponding phase-shifted sub-component of the RF signal; a first conductive trace which extends in a first direction and is coupled to the first output port and the second output port, and the slide device is configured to couple the input port to the first conductive trace and is able to slide with respect to the first conductive trace in the first direction. 
     A second aspect of the present disclosure is to provide remote electrical tilt system, which comprises an actuator, a transmission mechanism, and at least one phase shifter of any one of embodiments, wherein the actuator is configured to drive the transmission mechanism, and the transmission mechanism engages the first tooth section to drive the slide device to slide on the phase shift circuit board. 
     In some embodiments, the transmission mechanism includes a slider linkage configured with a second tooth section, and the slider linkage is configured to drive the slide device to slide on the phase shift circuit board by means of the engagement between the first tooth section of the slide device and the second tooth section of the slider linkage. 
     In some embodiments, the slider linkage is formed in a rack shape, and the slider support is formed in a sector gear shape, thereby forming a rack - gear transmission between the slider linkage and the slider support. 
     In some embodiments, the transmission mechanism includes a control rod which is configured to drive the slider linkage. 
     In some embodiments, the slider linkage is mounted on the control rod. 
     In some embodiments, the slider linkage is mounted on the control rod in a form-fitting manner. 
     In some embodiments, the slider linkage has an engaging portion, the control rod has a mating engaging portion, and the engaging portion is able to be embedded into the mating engaging portion in a form-fitting manner. 
     In some embodiments, the slider linkage is formed as a part of the control rod. 
     In some embodiments, the remote electrical tilt system includes a rail, and the control rod and the slider linkage are configured to be movable along the rail. 
     In some embodiments, the remote electrical tilt system further includes a bracket mounted on a base plate for supporting the rail. 
     In some embodiments, the bracket has a through slot, and the control rod is configured to extend into the rail through the through slot. 
     In some embodiments, the remote electrical tilt system includes a first bracket and a second bracket spaced apart from the first bracket, and the rail is supported between the first bracket and the second bracket. 
     In some embodiments, the control rod is driven by the actuator. 
     In some embodiments, the remote electrical tilt system includes a plurality of phase shifters respectively mounted on at least one base plate, and the transmission mechanism is configured to drive each slide device to slide on respective phase shift circuit board. 
     In some embodiments, the transmission mechanism includes one control rod configured to drive each slide linkage for each slide device. 
     In some embodiments, the remote electrical tilt system includes a first base plate, a first phase shifter and a second phase shifter mounted on the first base plate, wherein the first phase shifter has a first slide device, the second phase shifter has a second slide device, and the first tooth section of the first slide device and the first tooth section of the second slide device face each other. 
     In some embodiments, there is a gap between the first tooth section of the first slide device and the first tooth section of the second slide device, the slider linkage is able to be inserted into the gap, both sides of the slider linkage are respectively provided with second tooth sections, and the second tooth sections on both sides of the slider linkage are respectively engaged with the first tooth sections of the first and second slide device. 
     In some embodiments, the remote electrical tilt system includes a first base plate, at least one phase shifter mounted on the first base plate, a second base plate, and at least one phase shifter mounted on the second base plate. 
     In some embodiments, the first base plate and the second base plate are stacked one above the other. 
     In some embodiments, the transmission mechanism includes a control rod, a first slide linkage for driving the slide device of the phase shifter on the first base plate and a second slide linkage for driving the slide device of the phase shifter on the second base plate, wherein the control rod is able to drive the first slide linkage, and the first slide linkage is able to drive the second slide linkage. 
     In some embodiments, the first slide linkage is provided with a first engaging portion configured to engage with a first mating engaging portion on the control rod, and the first slide linkage is provided with a second engaging portion configured to engage with a second mating engaging portion on the second slide linkage. 
     In some embodiments, the first base plate is provided with a gap portion, and the second engaging portion is able to be embedded into the second mating engaging portion through the gap portion. 
     In some embodiments, the remote electrical tilt system includes a first rail, the control rod and the first slide linkage is configured to be movable along the first rail, and the first rail is supported on a bracket mounted on the first base plate, the remote electrical tilt system further includes a second rail, the second slide linkage is configured to be movable along the second rail, and the second rail is supported on a bracket mounted on the second base plate. 
     In some embodiments, the first base plate and the second base plate are horizontally placed. 
     In some embodiments, the transmission mechanism includes a control rod, a first slide linkage for driving the slide device of the phase shifter on the first base plate and a second slide linkage for driving the slide device of the phase shifter on the second base plate, wherein the control rod is able to drive the first slide linkage and the second slide linkage. 
     In some embodiments, the first slide linkage is provided with a first engaging portion configured to engage with a first mating engaging portion on the control rod, and the second slide linkage is provided with a second engaging portion configured to engage with a second mating engaging portion on the control rod. 
     In some embodiments, the engaging portion is configured as a convex portion and the mating engaging portion is configured as a groove; or the engaging portion is configured as a groove and the mating engaging portion is configured as a convex portion. 
     A third aspect of the present disclosure is to provide base station antenna, which comprises the remote electrical tilt system of any one of embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be explained in more detail below with reference to the accompanying drawings by means of specific embodiments. The schematic drawings are briefly described as follows: 
         FIG.  1   a    is a front view of a traditional RET system; 
         FIG.  1   b    is a perspective view of the RET system of  FIG.  1   a   ; 
         FIG.  2    is a perspective view of an RET system according to some embodiments of the present disclosure; 
         FIG.  3    is an exploded view of the RET system of  FIG.  2   ; 
         FIG.  4   a    is a perspective view of a slider linkage of the RET system of  FIG.  2   ; 
         FIG.  4   b    is a perspective view of the rail of the RET system of  FIG.  2   ; 
         FIG.  4   c    is a perspective view of the brackets of the RET system of  FIG.  2   ; 
         FIG.  4   d    is a perspective view of the slider support of the RET system of  FIG.  2   ; 
         FIG.  5    is a perspective view of the RET system according to some embodiments of the present disclosure; 
         FIG.  6    is an exploded view of the RET system of  FIG.  5   ; 
         FIG.  7   a    is a perspective view of the first slide linkage of the RET system of  FIG.  5   ; 
         FIG.  7   b    is a perspective view of the second slide linkage of the RET system of  FIG.  5   . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will be described with reference to the accompanying drawings, which show a number of example embodiments thereof. It should be understood, however, that the present disclosure may be embodied in many different ways, and is not limited to the embodiments described below. Rather, the embodiments described below are intended to make the present disclosure of the present disclosure more complete and fully convey the scope of the present disclosure to those skilled in the art. It should also be understood that the embodiments disclosed herein may be combined in any way to provide many additional embodiments. 
     It should also be understood that the terminology used herein is for the purpose of describing particular embodiments, but is not intended to limit the scope of the present disclosure. All terms (including technical terms and scientific terms) used herein have meanings commonly understood by those skilled in the art unless otherwise defined. For the sake of brevity and/or clarity, well-known functions or structures may be not described in detail. 
     Herein, when an element is described as located “on” “attached” to, “connected” to, “coupled” to or “in contact with” another element, etc., the element may be directly located on, attached to, connected to, coupled to or in contact with the other element, or there may be one or more intervening elements present. In contrast, when an element is described as “directly” located “on”, “directly attached” to, “directly connected” to, “directly coupled” to or “in direct contact with” another element, there are no intervening elements present. In the description, references that a first element is arranged “adjacent” a second element may mean that the first element has a part that overlaps the second element or a part that is located above or below the second element. 
     Herein, terms such as “upper”, “lower”, “left”, “right”, “front”, “rear”, “high”, “low” may be used to describe the spatial relationship between different elements as they are shown in the drawings. It should be understood that in addition to orientations shown in the drawings, the above terms may also encompass different orientations of the device during use or operation. For example, when the device in the drawings is inverted, a first feature that was described as being “below” a second feature may be then described as being “above” the second feature. The device may be oriented otherwise (rotated 90 degrees or at other orientation), and the relative spatial relationship between the features will be correspondingly interpreted. 
     Herein, the term “A or B” used through the specification refers to “A and B” and “A or B” rather than meaning that A and B are exclusive, unless otherwise specified 
     The term “exemplary”, as used herein, means “serving as an example, instance, or illustration”, rather than as a “model” that would be exactly duplicated. Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, summary, or detailed description. 
     Herein, the term “substantially”, is intended to encompass any slight variations due to design or manufacturing imperfections, device or component tolerances, environmental effects, and/or other factors. 
     Herein, certain terminology, such as the terms “first”, “second” and the like, may also be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, the terms “first”, “second” and other such numerical terms referring to structures or elements do not imply a sequence or order unless clearly indicated by the context. 
     Further, it should be noted that, the terms “comprise”, “include”, “have” and any other variants, as used herein, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. 
       FIGS.  1   a  and  1   b    are a front view and a perspective view of a traditional RET system  10 , respectively. As shown in  FIGS.  1   a  and  1   b   , the traditional RET system  10  may include a drive motor (not shown), a transmission mechanism, and a phase shifter  3  for the array of radiating elements. When cross-polarized radiating elements are used, two phase shifters  3  may be provided for one array of radiating elements to adjust the phases of the sub-components of the two polarized RF signals. Both phase shifters  3  may be mounted on one base plate  8  in common. The transmission mechanism of the traditional RET system  10  may include a control rod  1  and a slider linkage  2  mounted on the control rod  1 . The slider linkage  2  may have an elongate slot  6 . A pin  5  of the slide device  4  of the phase shifter  3  extends into the elongated slot  6 . When the control rod  1  is driven by the motor, the control rod  1  will drive the slider linkage  2 , and the slider linkage  2  may drive the slide device  4  to slide on a main circuit board  7  (that is, a phase shift circuit board with conductive traces printed thereon) of the phase shifter  3 , to change the phases of the sub-components of the RF signals and adjust the electrical tilt angle. 
     In addition, the performance of the phase shifter  3  is sensitive to pressure, because once the control rod  1  is tilted during the movement, it will increase the contact pressure between the slide device  4  of the phase shifter  3  and the main circuit board  7 , and the increased contact pressure will not only damage the phase shifter  3 , but also affect the phase shift performance of the phase shifter  3  and cause an increase in Return Loss. Therefore, it is necessary to ensure stable movement of the control rod  1  and the slider linkage  2 . For this, at least two brackets  9  may be installed on the base plate to stably support the control rod  1 . 
     However, in the traditional RET system  10 , the control rod  1  needs a reserved extra space (identified by a box in  FIG.  1   a   ). This extra space presents challenges to the spatial design of a base station antenna. Especially, as more and more devices are integrated into the base station antenna, this extra space is undesirable. Even in some application scenarios, this extra space is not allowed. In addition, since the slide device  4  needs a large pulling force as the deflection angle of the slide device  4  increases, the forces of the control rod  1  and the slider linkage  2  are not balanced throughout the entire stroke. 
     Next, the RET system  100  according to some embodiments of the present disclosure will be described in detail with the aid of  FIGS.  2  and  3   , and  FIGS.  4   a  to  4   d   .  FIGS.  2  and  3    are a perspective view and an exploded view of an RET system according to some embodiments of the present disclosure.  FIG.  4   a    is a perspective view of the slider linkage  20 ;  FIG.  4   b    is a perspective view of the rail  30 ;  FIG.  4   c    is a perspective view of the bracket  40 ; and  FIG.  4   d    is a perspective view of the slide device  50 . 
     As shown in  FIGS.  2  and  3   , the RET system  100  may include a drive motor (not shown), a transmission mechanism and phase shifter for an array of radiating elements. The RET system 100  may include multiple phase shifters. In the current embodiment, the RET system  100  may include a first phase shifter  61  and a second phase shifter  62  mounted on a base plate  70 , and the two phase shifters may be configured to adjust the phases of the sub-components of the two polarized RF signals. Each phase shifter may include a slide device  50  and a phase shift circuit board  51 . The slide device  50  is rotatably mounted on the phase shift circuit board  51  by means of a pivot shaft  52 . The phase shift circuit board  51  includes an input port, a plurality of output ports, and conductive traces  54  respectively coupled to two of the output ports. The slide device  50  is configured to couple the input port to the respective conductive traces  54  and may slide with respect to the conductive traces  54  to change the phase change experienced by the sub-components of the RF signal from the input port to the corresponding output port. 
     Referring to  FIG.  3   , the transmission mechanism of the RET system  100  may include a control rod  21  and a slider linkage  20 . A motor as an actuator may be configured to drive the control rod  21 . The driven control rod  21  may drive the slider linkage  20 , and the slider linkage  20  drives the slide device  50  to pivot on the phase shift circuit board  51 . In order to realize a more stable transmission, a rack-gear transmission may be used between the slider linkage  20  and the slide device  50 . In this regard, the slide device  50  may be configured with a sector gear section as a first tooth section  55 , and the slider linkage  20  may be configured with a rack section as a second tooth section  22 ; transmission with a more uniform torque may be realized through the meshing transmission between the first tooth section  55  and the second tooth section  22 . 
     Referring to  FIG.  4   d   , the slide device  50  may include a slider (not shown because it is on the back side of the slide device  50 ) and a slider support  56 . The slider may be configured as a slide circuit board printed with a first coupling part coupled to the input port and a second coupling part coupled to the corresponding conductive traces  54  respectively. The slider may be supported, for example, by being snapped on the slider support  56  made of a dielectric material. In some embodiments, the slider support  56  may be constructed as a plastic member. In the current embodiment, the slider support  56  may be configured with a sector gear section and cooperate with the rack section of the slider linkage  20 . It should be understood that the structure of the slide device  50  may be various, and in some embodiments, the slider itself may be configured with tooth sections. 
     In the embodiment of  FIG.  3   , the RET system  100  may include a first phase shifter  61  and a second phase shifter  62  mounted on a base plate  70 , wherein the first phase shifter  61  has a first slide device  501 , and the second phase shifter  62  has a second slide device  502 . In order to drive the first slide device  501  and the second slide device  502  at the same time, the slider linkage  20  may be provided with second tooth sections  22  on both sides thereof. The first tooth section  55  of the first slide device  501  and the first tooth section  55  of the second slide device  502  towards each other with a gap or a channel therebetween, and the slider linkage  20  may extend into the gap to engage respectively with the first tooth sections  55  of the two slide devices  50  by means of its own second tooth section  22 . 
     Referring still to  FIG.  3   , the RET system  100  may further include a rail  30  and a bracket  40  as shown in  FIG.  4   c    mounted on the base plate  70  for supporting the rail  30 . In the current embodiment, the RET system  100  may include a first bracket  40  and a second bracket  40  spaced apart from the first bracket  40 . The rail  30  may be bridged between the two brackets  40  and provide support for the control rod  21  together with the slider linkage  20 . The distance between the two brackets  40  or the length of the rail  30  may substantially correspond to the complete stroke of the control rod  21 . Thereby, the control rod  21  does not need to move out of the bracket  40  or at least less outside of the bracket  40 , so that the extra space reserved for the stroke of the control rod  21  shown in  FIG.  1   a    may be avoided or at least reduced. 
     Referring to  FIG.  3    and  FIG.  4   c   , the bracket  40  may be provided with a through slot  42 , wherein the control rod  21  is configured to be able to pass through the through slot  42  and extend into the rail  30 . Referring to  FIG.  4   b   , the rail  30  may be configured as two separate work profiles  32 . The two work profiles  32  may be inserted into the receiving slot  44  on the bracket  40  and fixed in the receiving slot  44 . The control rod  21  together with the slider linkage  20  may extend into the rail  30  formed by the two work profiles  32  and move smoothly along the rail  30 . In other embodiments, the rail  30  may be configured into any other suitable structure, and the shape and size of the rail  30  may be adaptively changed according to the design of the control rod  21  and/or the slider linkage  20 . In other embodiments, the rail  30  may also be configured in one piece. The reliable and stable support by the rail  30  further improves the stable movement of the control rod  21  and the slider linkage  20 , so that a large fluctuation in the contact pressure between the slide device  50  and the main circuit board due to the unstable movement of the control rod  21  are prevented, thus maintaining the performance of the phase shifter  60  at an acceptable level. 
     In the current embodiment, the slider linkage  20  may be mounted on the control rod  21  as a separate member. For example, the slider linkage  20  may be mounted on the control rod  21  in a form-fitting manner. As shown in  FIG.  4   a   , the slider linkage  20  has a convex portion  23  as an engaging portion in addition to the tooth sections provided on both sides thereof, and the convex portion  23  may be fitted on the control rod  21  to match the engaging portion thereof, that is, the groove  24 . In some embodiments, the slider linkage  20  may be provided with a groove, and the control rod  21  may be provided with a convex portion. In other embodiments, the slider linkage  20  may be mounted on the control rod  21  by any other suitable joining method, for example, by material joining methods such as welding, or by additional fastening means such as rivets or screws. In other embodiments, the slider linkage  20  may be integrally formed with and configured as part of the control rod  21 . 
     Next, the RET system  100 ′ according to some embodiments of the present disclosure will be described in detail with reference to  FIGS.  5 ,  6 ,  7   a , and  7   b   .  FIG.  5    is a perspective view of the RET system  100 ′;  FIG.  6    is an exploded view of the RET system  100 ′;  FIG.  7   a    is a perspective view of the first slide linkage  201  of the RET system  100 ′;  FIG.  7   b    is a perspective view of the second slide linkage  202  of the RET system  100 ′. 
     In the actual operation of a base station antenna, it may be necessary to implement a synchronized phase shift operation on two or more arrays of radiating elements. In this case, the RET system  100 ′ may include a plurality of base plates, and each base plate may have at least one phase shifter. 
     As shown in  FIGS.  5  and  6   , the RET system  100 ′ may have a first base plate  701  and a second base plate  702 . For example, a first phase shifter  61  and a second phase shifter  62  for the two polarized RF signals are mounted on the first base plate  701 . The first phase shifter  61  has a first slide device  501  and a first phase shift circuit board  511 , and the second phase shifter  62  has a second slide device  502  and a second phase shift circuit board  512 . In the current embodiment, the first base plate  701  and the second base plate  702  may be stacked on top of each other, thereby improving the compact structure of the antenna. Of course, in other embodiments, the first base plate  701  and the second base plate  702  may also lie horizontally to each other. As for the specific structure of the phase shift circuit boards  511 ,  512  and the slide device  501 ,  502 , reference may be made to the content described for  FIG.  2    to 4d, which will not be repeated here. Next, the transmission mechanism of the RET system  100 ′ according to this embodiment will be described in detail. 
     Referring to  FIG.  6   , the transmission mechanism may include a control rod  21 , a first slide linkage  201  for driving the first slide device  501  and a second slide linkage  202  for driving the second slide device  502 . A motor may be used for driving the control rod  21  (typically only one) as a driving device, and the control rod  21  may drive the first slide linkage  201 . The first slide linkage  201  further drives the first slide device  501  to pivot on the first phase shift circuit board  511 . In addition, the first slide linkage  201  may further drive the second slide linkage  202 , so that the second slide linkage  202  further drives the second slide device  502  to pivot on the second phase shift circuit board  512 . In order to achieve a more stable transmission, the rack-gear transmission as already described above may be used between the first slide linkage  201  and the first slide device  501  and/or between the second slide linkage  202  and the second slide device  502 . 
     Referring still to  FIG.  6   , the RET system  100 ′ may further include a first rail  601  and a second rail  602 . The control rod  21  and the first slide linkage  201  may move along the first rail  601 , and the first rail  601  is supported on a bracket  40  mounted on the first base plate  701 . The second slide linkage  202  may move along the second rail  602 , and the second rail  202  is supported on the bracket  40  mounted on the second base plate  702 . Thereby, the control rod  21  does not need to move out of the bracket  40  or at least less outside the bracket  40 , so that the extra space reserved for the stroke of the control rod  21  shown in  FIG.  1   a    may be avoided or at least reduced. 
     Referring to  FIGS.  7   a  and  7 B , the first slide linkage  201  may be provided with a first convex portion  203  as the first engaging portion, the first convex portion  203  is configured to be engaged with the groove on the control rod  21 , so that they form a reliable first matching structure. In addition, the first slide linkage  201  may be further provided with a second convex portion  205  as the second engaging portion, and the second convex portion  205  may be embedded into the gap portion on the first base plate  701  to fit in the groove  206  on the second slide linkage  202 , so that they form a reliable second mating structure. The first matching structure and the second matching structure enable the control rod  21  to drive the slider linkages  201  and  202  on different base plates  701  and  702 . It should be understood that the first slide linkage  201  may be mounted on the control rod  21  by any other suitable joining method, for example by material joining method such as welding or by additional fastening means such as rivets or screws. Similarly, the second slide linkage  202  may be mounted on the first slide linkage  201  by any other suitable joining method, for example, by material joining methods such as welding, or by additional fastening devices such as rivets or screws. In other embodiments, the first slide linkage  201  and the second slide linkage  202  may be integrally formed with the control rod  21 . 
     In some embodiments, the first base plate and the second base plate may lie horizontally. In this case, the transmission mechanism may include a control rod (typically only one), a first slide linkage for driving the slide device of the phase shifter on the first base plate, and a second slide linkage for driving the slide device of the phase shifter on the second base plate. The control rod may drive the first slide linkage and the second slide linkage. The first slide linkage may be provided with a first engaging portion configured to engage with a first mating engaging portion on the control rod, and the second slide linkage is provided with a second engaging portion configured to engage with the second mating engaging portion on the control rod, thereby achieving reliable transmission. It should be understood that according to some embodiments of the present disclosure, the RET system  100 ,  100 ′ may drive a plurality of slide linkages  20  through a control rod  21  driven by a motor, the plurality of slide linkages  20  may accordingly drive the associated slide device  50  to perform a synchronized phase shift operation for each phase shifter  60 . 
     Although exemplary embodiments of the present disclosure have been described, it should be understood by a person skilled in the art that, various changes and modifications can be made to the exemplary embodiments of the present disclosure without substantially departing from the spirit and scope of the present disclosure. Therefore, all changes and modifications are included in the protection scope of the present disclosure as defined by the claims. This disclosure is defined by the appended claims, and the equivalents of these claims are also included.