Actuators for controlling multiple phase shifters of remote electronic downtilt base station antennas

Multi-RET actuators include a plurality of shafts that have respective axially-drivable members mounted thereon. Each of axially-drivable member is mechanically linked to a respective one of a plurality of phase shifters. The multi-RET actuator further includes a motor having a drive shaft and a gear system that is configured to selectively couple the motor to the respective shafts. The gear system is configured so that rotation of the drive shaft in a first direction creates a mechanical linkage between the motor and a first of the shafts 1340/1342, and rotation of the drive shaft in a second direction that is opposite the first direction rotates the first of the shafts.

FIELD OF THE INVENTION

The present invention relates to communication systems and components, and in particular to actuators for electromechanical phase shifters used in base station antennas.

BACKGROUND

Base station antennas for wireless communication systems are used to transmit radio frequency (“RF”) signals to, and receive RF signals from, cellular. Base station antennas are directional devices that can concentrate the RF energy that is transmitted in certain directions (or received from those directions). The “gain” of a base station antenna in a given direction is a measure of the ability of the antenna to concentrate the RF energy in that particular direction. The “radiation pattern” of a base station antenna is compilation of the gain of the antenna across all different directions. The radiation pattern of a base station antenna is typically designed to service a pre-defined coverage area, which refers to a geographic region in which mobile users can communicate with the cellular network through the base station antenna. The base station antenna may be designed to have minimum gain levels throughout this pre-defined coverage area, and it is typically desirable that the base station antenna have much lower gain levels outside of the coverage area. Early base station antennas typically had a fixed radiation pattern, meaning that once a base station antenna was installed, its radiation pattern could not be changed unless a technician physically reconfigured the antenna. Unfortunately, such manual reconfiguration of base station antennas after deployment, which could become necessary due to changed environmental conditions or the installation of additional base stations, was typically difficult, expensive and time-consuming.

More recently, base station antennas have been deployed that have radiation patterns that can be reconfigured from a remote location. For example, base station antennas have been developed for which settings such as the down tilt angle, beam width and/or azimuth angle of the antenna can be reconfigured from a remote location by transmitting control signals to the antenna. Base station antennas that can have their down tilt or “elevation” angle changed from a remote location are typically referred to as remote electrical tilt (“RET”) antennas, although the term “RET antenna” is now also commonly used to cover antennas that can have their azimuth angle and/or beam width adjusted from a remote location. RET antennas allow wireless network operators to remotely adjust the radiation pattern of the antenna through the use of electro-mechanical actuators that may adjust phase shifters or other devices in the antenna to affect the radiation pattern of the antenna. Typically, the radiation pattern of a RET antenna is adjusted using actuators that are controlled via control signal specifications promulgated by the Antenna Interface Standards Group (“AISG”).

Base station antennas typically comprise a linear array or a two-dimensional array of radiating elements such as dipole or crossed dipole radiating elements. In order to change the down tilt angle of these antennas, a phase taper may be applied across the radiating elements, as is well understood by those of skill in the art. Such a phase taper may be applied by adjusting the settings on an adjustable phase shifter that is positioned along the RF transmission path between a radio and the individual radiating elements of the base station antenna. One known type of phase shifter is an electromechanical “wiper” phase shifter that includes a main printed circuit board and a “wiper” printed circuit board that may be rotated above the main printed circuit board. Such wiper phase shifters typically divide an input RF signal that is received at the main printed circuit board into a plurality of sub-components, and then capacitively couple at least some of these sub-components to the wiper printed circuit board. These sub-components of the RF signal may be capacitively coupled from the wiper printed circuit board back to the main printed circuit board along a plurality of arc-shaped traces, where each arc has a different diameter. Each end of each arc-shaped trace may be connected to a radiating element or to a sub-group of radiating elements. By physically rotating the wiper printed circuit board above the main printed circuit board, the location where the sub-components of the RF signal capacitively couple back to the main printed circuit board may be changed, which thus changes the path lengths from the phase shifter to the radiating elements. This change in the path lengths results in a change in the phase of the sub-components of the RF signal, and since the arcs have different radii, the change in phase experienced along each path differs. Typically, the phase taper is applied by applying positive phase shifts of various magnitudes (e.g., +1°, +2° and +3°) to some of the sub-components of the RF signal and by applying negative phase shifts of the same magnitudes (e.g., −1°, −2° and −3°) to additional of the sub-components of the RF signal. Thus, the above-described wiper phase shifters may be used to apply a phase taper to the sub-components of an RF signal that are applied to each radiating element (or sub-group of radiating elements). Exemplary phase shifters of this variety are discussed in U.S. Pat. No. 7,907,096 to Timofeev, the disclosure of which is hereby incorporated herein in its entirety. The wiper printed circuit board is typically moved using an electromechanical actuator such as a DC motor that is connected to the wiper printed circuit board via a mechanical linkage. These actuators are often referred to as RET actuators since they are used to apply the remote electronic down tilt.

SUMMARY

Pursuant to embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a plurality of axially-drivable members, each axially-drivable member mounted on a respective parallel shaft, the axially-drivable members configured to be connected with a respective one of the phase shifters, a drive member having a primary rotary member, and a plurality of secondary rotary members, each secondary rotary member mounted on a respective one of the parallel shafts. At least one of the primary rotary member and the secondary rotary members are axially movable so that each secondary rotary member may be in either an engaged position, in which the secondary rotary member engages the drive member, and a disengaged position, in which the secondary rotary member is disengaged from the drive member. The actuator further includes a first engagement mechanism that is configured to axially move the primary rotary member or one of the secondary rotary members so that at least one of the secondary rotary members is in the engaged position and an electric motor that is configured to drive the drive member. The first engagement mechanism may comprise an electromagnetic or a piezoelectric engagement mechanism.

In some embodiments, the first engagement mechanism is an electromagnetic engagement mechanism that includes an electromagnet. The first engagement mechanism may further include a permanent magnet or a ferromagnetic structure that is axially aligned with the electromagnet. The first engagement mechanism may also include a spring that is between the permanent magnet or ferromagnetic structure and the electromagnet.

In some embodiments, the first engagement mechanism is one of a plurality of engagement mechanisms, and each of the engagement mechanisms is configured to selectively move a respective one of the secondary rotary members.

In some embodiments, the first engagement mechanism is configured to move the primary rotary member to selectively engage the primary rotary member with one of the secondary rotary members.

In some embodiments, the parallel shafts comprise worm gear shafts.

In some embodiments, the primary rotary member is a central gear and each of the secondary rotary members are gears.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the spring biases one of the secondary rotary member toward the disengaged position.

In some embodiments, the actuator may be part of a base station antenna that includes a plurality of linear arrays of radiating elements, where each of the phase shifters is coupled between the radiating elements of a respective one of the linear arrays and a port of a radio.

Pursuant to further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a motor that is configured to rotate a primary rotary member, a plurality of axially-drivable members, each axially-drivable member mounted on a respective shaft and configured to be connected with a respective one of the phase shifters, a plurality of secondary rotary members, each secondary rotary member mounted so that rotation thereof will result in rotation of a respective one of the shafts, and an electromagnet that is configured to move either the primary rotary member or a selected one of the secondary rotary members in response to a control signal so that the primary rotary member engages the selected one of the secondary rotary members.

In some embodiments, the electromagnet is configured to move the primary rotary member into engagement with the selected one of the secondary rotary members.

In some embodiments, the actuator may further include a permanent magnet or a ferromagnetic structure that is axially aligned with the electromagnet, where the electromagnet is attracted to the permanent magnet or ferromagnetic structure in response to the control signal.

In some embodiments, the actuator may further include a spring that is between the permanent magnet or ferromagnetic structure and the electromagnet, the spring biasing the primary rotary member into a disengaged position in which the primary rotary member is not engaged with any of the secondary rotary members.

In some embodiments, the actuator may further include a permanent magnet that is axially aligned with the electromagnet, where the electromagnet is repelled from the permanent magnet in response to the control signal.

In some embodiments, the actuator may further include a spring that biases the primary rotary member into a disengaged position in which the primary rotary member is not engaged with any of the secondary rotary members, where the primary rotary member is between the spring and the electromagnet.

In some embodiments, the spring may be a first spring, and the actuator may further include a second spring and the primary rotary member may be between the first and second springs.

In some embodiments, the primary rotary member is mounted on a shaft that is configured to be turned by the motor, and the primary rotary member is mounted for axial movement along the shaft and to rotate in response to rotation of the shaft.

In some embodiments, the electromagnet is configured to move the selected one of the secondary rotary members into engagement with the primary rotary member.

In some embodiments, the actuator may further include a permanent magnet or a ferromagnetic structure that is axially aligned with the electromagnet, where the electromagnet is attracted to the permanent magnet or ferromagnetic structure in response to the control signal.

In some embodiments, the actuator may further include a spring that is between the permanent magnet or ferromagnetic structure and the electromagnet, the spring biasing the selected one of the secondary rotary members into a disengaged position in which the primary rotary member is not engaged with the selected on of the secondary rotary members.

In some embodiments, the actuator may further include a permanent magnet that is axially aligned with the electromagnet, where the electromagnet is repelled from the permanent magnet in response to the control signal.

In some embodiments, the selected one of the secondary rotary members includes a rear portion having an internal cavity, the internal cavity receiving an end of a respective one of the shafts when the selected one of the secondary rotary members is engaged with the primary rotary member.

In some embodiments, the electromagnet is one of a plurality of electromagnets and the control signal is one of a plurality of control signals, and each electromagnet is configured to move a respective one of the secondary rotary members into engagement with the primary rotary member in response to a respective one of the control signals.

In some embodiments, each of the shafts comprises a worm gear shaft, the primary rotary member is a central gear and each of the secondary rotary members are gears.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a motor that is configured to rotate a primary rotary member, a plurality of axially-drivable members, each axially-drivable member mounted on a respective shaft, each axially-drivable member configured to be connected with a respective one of the phase shifters, a plurality of secondary rotary members, each secondary rotary member mounted so that rotation thereof will result in rotation of a respective one of the shafts, and a piezoelectric actuator that is configured to move a selected one of the secondary rotary members in response to a control signal to be rotatably engaged with the primary rotary member.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a plurality of axially-drivable members, each axially-drivable member mounted on a respective parallel shaft, the axially-drivable members configured to be connected with a respective one of the phase shifters, a central drive member, a plurality of rotary members, each mounted on a respective one of the parallel shafts, an engagement mechanism that is configured to rotate to selectively and exclusively engage each of the shafts to move a respective rotary member to the engaged position a first drive unit to drive the central drive member, and a second drive unit configured to drive the engagement mechanism. Each of the rotary members is axially movable between an engaged position, in which the rotary member engages the central drive member, and a disengaged position, in which each rotary member is disengaged from the central drive member.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shafts that bias the rotary members toward the disengaged position.

In some embodiments, the engagement mechanism comprises a cam that engages one of the parallel shafts to move a respective rotary member attached to the shaft to the engaged position.

In some embodiments, the engagement mechanism includes a ring gear, and wherein the ring gear engages the second drive unit.

In some embodiments, the central drive member is a central drive gear.

In some embodiments, the rotary members are gears.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a plurality of axially-drivable members, each axially-drivable member mounted on a respective parallel shaft, the axially-drivable members configured to be connected with a respective one of the phase shifters, a central drive gear, a plurality of gears, each mounted on a respective one of the parallel shafts, an engagement mechanism that is configured to rotate to selectively and exclusively engage each of the shafts to move a respective gear to the engaged position in which the gear engages the central drive gear, a first drive unit to drive the central drive gear, and a second drive unit configured to drive the engagement mechanism.

In some embodiments, the axially-drivable members comprise pistons and/or the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shafts that bias the gears toward the disengaged position.

In some embodiments, the engagement mechanism comprises a cam that engages one of the parallel shafts to move a respective gear attached to the shaft to the engaged position.

In some embodiments, the engagement mechanism includes a ring gear, and wherein the ring gear engages the second drive unit.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a plurality of axially-drivable members, each axially-drivable member mounted on a respective parallel shaft, the axially-drivable members configured to be connected with a respective one of the phase shifters, a central drive gear, a plurality of gears that are mounted on respective ones of the parallel shafts and that are each axially movable between an engaged position, in which the gear engages the central drive gear, and a disengaged position, in which each gear is disengaged from the central drive gear, a cam plate with a cam that is configured to rotate such that the cam selectively and exclusively engages each of the shafts to move a respective gear to the engaged position, a first drive unit to drive the central drive gear, and a second drive unit configured to drive the cam plate.

In some embodiments, the axially-drivable members comprise pistons and/or the parallel shafts comprise worm gear shafts.

In some embodiments, the parallel shafts include spring-loaded shafts that bias the gears toward the disengaged position.

In some embodiments, the cam plate includes a ring gear, and the ring gear engages the second drive unit.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a plurality of shafts having respective axially-drivable members mounted thereon, each axially-drivable member configured to be connected with a respective one of the phase shifters, a motor having a drive shaft, and a gear system that is configured to selectively couple the motor to the respective shafts. The gear system is configured so that rotation of the drive shaft in a first rotative direction creates a mechanical linkage between the motor and a first of the shafts, and rotation of the drive shaft in a second rotative direction that is opposite the first rotative direction rotates the first of the shafts.

In some embodiments, the gear system includes a forward-direction primary drive gear that is connected to the drive shaft and a reverse-direction primary drive gear that is connected to the drive shaft

In some embodiments, the forward-direction primary drive gear and the reverse-direction primary drive gear are each ratcheted gears that rotate in response to rotation of the drive shaft in the second rotative direction and which do not rotate in response to rotation of the drive shaft in the first rotative direction.

In some embodiments, the actuator further includes a reversing gear that is configured to engage the reverse-direction primary drive gear and rotate in a direction opposite to the direction of rotation of the reverse-direction primary drive gear.

In some embodiments, the gear system further includes a plurality of secondary drive members mounted on respective ones of the shafts, each secondary drive member mounted so that rotation thereof will result in rotation of a respective one of the shafts.

In some embodiments, the gear system includes an engagement mechanism that is configured to rotate to selectively and exclusively engage one or more of the shafts to move a selected one of the secondary drive members into engagement with one of the forward-direction primary drive gear or the reversing gear.

In some embodiments, the engagement member comprises a rotating cam plate.

Pursuant to still further embodiments of the present invention, a method of adjusting a phase shifter is provided in which a drive shaft is rotated in a first rotative direction to connect a first of a plurality of gears to a drive mechanism and then the drive shaft is rotated in a second rotative direction to rotate the drive mechanism, where rotation of the drive mechanism causes rotation of the first of the plurality of gears and rotation of the first of the plurality of gears mechanically adjusts a physical position of a component of the phase shifter.

In some embodiments, the plurality of gears comprises a plurality of secondary drive gears that are configured to rotate respective shafts, and the drive mechanism comprises a forward-direction primary drive gear that is connected to the drive shaft and a reverse-direction primary drive gear that is connected to the drive shaft.

In some embodiments, the forward-direction primary drive gear is a ratcheted gear that only rotates in response to rotation of the drive shaft in a first rotative direction.

In some embodiments, the reverse-direction primary drive gear is a ratcheted gear that only rotates in response to rotation of the drive shaft in the first rotative direction.

In some embodiments, rotating the drive shaft in the first rotative direction to connect the first of the plurality of gears to the drive mechanism comprises using the rotating drive shaft to rotate a cam to move the first of the plurality of gears into operative engagement with one of the forward-direction primary drive gear or the reverse-direction primary drive gear.

In some embodiments, at least one of the forward-direction primary drive gear or the reverse-direction primary drive gear is configured to engage the first of the plurality of gears through an intervening reversing gear.

Pursuant to still further embodiments of the present invention, an actuator for a plurality of phase shifters is provided that includes a motor that is configured to rotate a primary rotary member, a plurality of axially-drivable members, each axially-drivable member mounted on a respective shaft, each axially-drivable member configured to be connected with a respective one of the phase shifters, a plurality of secondary rotary members, each secondary rotary member mounted so that rotation thereof will result in rotation of a respective one of the shafts, and a plurality of micro-motors, each micro-motor configured to rotate a respective one of the shafts.

In some embodiments, the shafts comprise worm gear shafts.

In some embodiments, the primary rotary member is a central gear and each of the secondary rotary members are gears.

In some embodiments, the axially-drivable members comprise pistons.

In some embodiments, the actuator further includes a plurality of springs that are mounted on the respective shafts, each spring configured to bias a respective one of the secondary rotary member toward a disengaged position where the secondary rotary member does not engage the primary drive member.

DETAILED DESCRIPTION

Modern base station antennas often include two, three or more linear arrays of cross-polarized radiating elements. Thus, it is not uncommon for a base station antenna to have eight, twelve or even more adjustable phase shifters for applying remote electronic down tilts to the linear arrays. Such a large number of phase shifters and associated RET actuators and mechanical linkages can significantly increase the size, weight and cost of the base station antenna.

Conventionally, a separate RET actuator has been provided for each phase shifter (or pair of phase shifters if dual polarized radiating elements are used in a linear array, as the same phase shift is typically applied to each polarization). More recently, RET actuators have been proposed that may be used to move the wiper printed circuit board on as many as twelve phase shifters. For example, U.S. Patent Publication No. 2013/0307728 (“the '728 publication”) discloses a RET actuator that may be used to drive six different mechanical linkages for purposes of adjusting six different phase shifters using one multi-RET actuator.

Pursuant to embodiments of the present invention, fully automated multi-RET actuators are provided. The multi-RET actuators according to embodiments of the present invention may be controlled from a remote location to independently adjust the settings of one or more of a plurality of phase shifters. In some embodiments, the multi-RET actuators include two motors. In these embodiments, the first motor may operate to select one of a plurality of mechanical linkages that is to be moved, and the second motor may be used to move the selected mechanical linkage. In other embodiments, single motor multi-RET actuators are provided. In some of these single-motor embodiments, a ratcheted gear system may be provided that allows the motor to both select the mechanical linkage that is to be moved and to then move the selected mechanical linkage. In other embodiments, a separate actuator system such as, for example, remotely controlled electromagnets may be used to select the mechanical linkage that is to be moved, and the single motor may then be used to move the selected mechanical linkage. In still other embodiments, multi-RET actuators are provided that use a main drive motor and a plurality of micro-motors.

The multi-RET actuators according to embodiments of the present invention may be used to rotate a primary drive gear (or a pair of primary drive gears in one embodiment) that is mounted on the drive shaft of a motor. A plurality of worm gear shafts are provided, each of which has a respective secondary drive gear associated therewith. A selected one or more of the secondary drive gears may be moved to engage the primary drive gear. Each secondary drive gear may be connected to its associated worm gear shaft so that rotation of the primary drive gear causes the selected secondary drive gear to rotate, which in turn imparts rotational movement to the worm gear shaft on which the selected secondary drive gear is mounted. Rotation of the worm gear shaft causes a piston mounted thereon to move along the longitudinal axis of its worm gear shaft. Each piston may be connected via a mechanical linkage to a wiper arm on an adjustable phase shifter so that movement of the piston may be used to adjust the setting of the phase shifter.

In order to allow the adjustable phase shifters that are connected to each respective mechanical linkage to be independently adjusted, the multi-RET actuators according to embodiments of the present invention can select which of the secondary drive gears contacts the primary drive gear so that movement of the primary drive gear results in corresponding rotation of only the selected secondary drive gear. In some embodiments, electromagnets may be used to move selected ones of the secondary drive gears into engagement with the primary drive gear in response to control signals from a remote location. In other embodiments, piezoelectric actuators may be used to move selected ones of the secondary drive gears into engagement with the primary drive gear. In still other embodiments, other electro-mechanical mechanisms may be provided that move selected ones of the secondary drive gears into engagement with the primary drive gear. In further embodiments, micro-motors may be used to move selected ones of the secondary drive gears into engagement with the primary drive gear. In still other embodiments, an indexing cam plate may be used to move selected ones of the secondary drive gears into engagement with the primary drive gear. Moreover, while the embodiments discussed below primarily (but not exclusively) discuss actuators in which the selected secondary drive gears are moved to engage the primary drive gear, it will be appreciated that in other embodiments the primary drive gear may be moved to engage one or more selected secondary drive gears.

Embodiments of the present invention will now be discussed in greater detail with reference to the drawings.

FIG. 1Ais a perspective view of a RET base station antenna100that may include any of the multi-RET actuators according to embodiments of the present invention that are disclosed herein.FIG. 1Bis an end view of the base station antenna100that illustrates the input/output ports thereof.FIG. 1Cis a schematic plan view of the base station antenna100that illustrates the three linear arrays of radiating elements thereof.FIG. 2is a schematic block diagram illustrating various internal components of the RET antenna100and the connections therebetween. It should be noted thatFIG. 2does not show the actual location of the various elements on the antenna, but instead is drawn to shown the connections between the various elements with a minimal number of connection lines crossing. It will also be appreciated that the connection lines inFIG. 2represent paths for electrical signals (e.g., RF transmission lines).

Referring toFIGS. 1A-1C and 2, the RET antenna100includes, among other things, input/output ports110, a plurality of linear arrays120of radiating elements130, duplexers140, phase shifters150and control ports170. As shown inFIGS. 1C and 2, the antenna100includes a total of three linear arrays120(labeled120-1through120-3) that each include five radiating elements130. It will be appreciated, however, that the number of linear arrays120and the number of radiating elements130included in each of the linear arrays120may be varied. It will also be appreciated that different linear arrays120may have different numbers of radiating elements130.

Referring toFIG. 2, the connections between the input/output ports110, radiating elements130, duplexers140and phase shifters150are schematically illustrated. Each set of an input port110and a corresponding output port110, and their associated phase shifters150and duplexers140, may comprise a corporate feed network160. A dashed box is used to illustrate one such corporate feed network160inFIG. 2. Each corporate feed network160connects the radiating elements130of one of the linear arrays120to a respective pair of input/output ports110.

As shown schematically inFIG. 2by the “X” that is included in each box, the radiating elements130may be cross-polarized radiating elements130such as +45°/−45° slant dipoles that may transmit and receive RF signals at two orthogonal polarizations. Any other appropriate radiating element130may be used including, for example, single dipole radiating elements or patch radiating elements (including cross-polarized patch radiating elements). When cross-polarized radiating elements130are used, two corporate feed networks160may be provided per linear array120, a first of which carries RF signals having the first polarization (e.g., +45°) between the radiating elements130and a first pair of input/output ports110and the second of which carries RF signals having the second polarization (e.g., −45°) between the radiating elements130and a second pair of input/output ports110, as shown inFIG. 2.

As shown inFIG. 2, an input port of each transmit (“TX”) phase shifter150may be connected to a respective one of the input ports110. Each input port110may be connected to the transmit output port of a radio (not shown) such as a remote radio head. Each transmit phase shifter150has five output ports that are connected to respective ones of the radiating elements130through respective duplexers140. The transmit phase shifters150may divide an RF signal that is input to an input port110into a plurality of sub-components and may effect a phase taper to the sub-components of the RF signal that are provided to the radiating elements130. In a typical implementation, a linear phase taper may be applied to the radiating elements130. As an example, the first radiating element130in a linear array120may have a phase of Y°+2X°, the second radiating element130in the linear array120may have a phase of Y°+X°, the third radiating element130in the linear array120may have a phase of Y°, the fourth radiating element130in the linear array120may have a phase of Y°−X°, and the fifth radiating element130in the linear array120may have a phase of Y°−2X°, where the radiating elements130are arranged in numerical order.

Similarly, each receive (“RX”) phase shifter150may have five input ports that are connected to respective ones of the radiating elements130through respective duplexers140and an output port that is connected to one of the output ports110, The output port110may be connected to the receive port of a radio (not shown). The receive phase shifters150may effect a phase taper to the RF signals that are received at the five radiating elements130of the linear array120and may then combine those RF signals into a composite received RF signal. Typically, a linear phase taper may be applied to the radiating elements as is discussed above with respect to the transmit phase shifters150.

The duplexers140may be used to couple each radiating element130to both a transmit phase shifter150and to a receive phase shifter150. As is well known to those of skill in the art, a duplexer is a three port device that (1) passes signals in a first frequency band (e.g., the transmit band) through a first port while not passing signals in a second band (e.g., a receive band), (2) passes signals in the second frequency band while not passing signals in the first frequency band through a second port thereof and (3) passes signals in both the first and second frequency bands through the third port thereof, which is often referred to as the “common” port.

As can be seen fromFIG. 2, a base station antenna100that includes three linear arrays120of radiating elements130may include a total of twelve phase shifters150. While the two transmit phase shifters150for each linear array120(i.e., one transmit phase shifter150for each polarization) may not need to be controlled independently (and the same is true with respect to the two receive phase shifters150for each linear array120), there still are six sets of two phase shifters150that should be independently controllable. Accordingly, six RET actuators would conventionally be used in a base station antenna having the linear array arrangement of base station antenna100.

The base station antenna100may include various other components such as low noise amplifiers, one or more processors, etc. that are not pictured inFIGS. 1A-1C and 2.

Each phase shifter150shown inFIG. 2may be implemented as a rotating wiper phase shifter. The phase shifts imparted by the phase shifter150to each sub-component of the RF signal may be controlled by a mechanical positioning system that physically changes the position of the rotating wiper of each phase shifter150, as will be explained with reference toFIG. 3.

Referring toFIG. 3, a dual rotating wiper phase shifter assembly200is illustrated that may be used to implement, for example, two of the transmit phase shifters150ofFIG. 2(that are associated with the same linear array120) or two of the receive phase shifters150ofFIG. 2(that, again, are associated with the same linear array120). The dual rotating wiper phase shifter assembly200includes first and second phase shifters202,202a. In the description ofFIG. 3that follows it is assumed that the two phase shifters202,202aare each transmit phase shifters that have one input and five outputs. It will be appreciated that if the phase shifters202,202aare instead used as receive phase shifters then the terminology changes, because when used as receive phase shifters there will be five inputs and a single output.

As shown inFIG. 3, the dual phase shifter200includes first and second main (stationary) printed circuit boards210,210athat are arranged back-to-back as well as first and second rotatable wiper printed circuit boards220,220a(wiper printed circuit board220ais barely visible in the view ofFIG. 3) that are rotatably mounted on the respective main printed circuit boards210,210a. The wiper printed circuit boards220,220amay be pivotally mounted on the respective main printed circuit boards210,210avia a pivot pin222. The two rotatable wiper printed circuit boards220,220amay be joined together at their distal ends via a bracket224.

The position of each rotatable wiper printed circuit boards220,220aabove its respective main printed circuit board210,210ais controlled by the position of a linkage shaft228, the end of which may constitute one end of a mechanical linkage226. The other end of the mechanical linkage226(not shown) may be coupled to a multi-RET actuator according to embodiments of the present invention, as will be discussed in further detail below. A position sensor250may be provided on one of the rotatable wiper printed circuit boards220,220ato detect the position of the rotatable wiper printed circuit boards220,220a.

Each main printed circuit board210,210aincludes a plurality of transmission line traces212,214. The transmission line traces212,214are generally arcuate. In some cases the arcuate transmission line traces212,214may be disposed in a serpentine pattern to achieve a longer effective length. In the example illustrated inFIG. 3, there are two arcuate transmission line traces212,214per main printed circuit board210,210a(the traces on printed circuit board210aare not visible inFIG. 3), with the first arcuate transmission line trace212being disposed along an outer circumference of each printed circuit board210,210a, and the second arcuate transmission line trace214being disposed on a shorter radius concentrically within the outer transmission line trace212. A third transmission line trace216on each main printed circuit board210,210aconnects an input pad230on each main printed circuit board210,210ato an output pad240that is not subjected to an adjustable phase shift.

The main printed circuit board210includes one or more input traces232leading from the input pad230near an edge of the main printed circuit board210to the position where the pivot pin222is located. RF signals on the input trace232are coupled to the transmission line traces on the wiper printed circuit board220(not visible inFIG. 3). The RF signals are coupled from the transmission line traces on the wiper printed circuit board220to the transmission line traces212,214on the main printed circuit board. Each end of each transmission line trace212,214may be coupled to a respective output pad240. A coaxial cable260or other RF transmission line component may be connected to input pad230(a coaxial cable260ais also coupled to the corresponding input pad on the main printed circuit board210aof phase shifter202a). A respective coaxial cable270or other RF transmission line component may be connected to each respective output pad240(coaxial cables270amay likewise be coupled to the corresponding output pads on the main printed circuit board210aof phase shifter202a). Connections other than coaxial cables260,270may be used in other embodiments. For example, in other embodiments, the main printed circuit board210may be coupled to stripline transmission lines on a panel without additional coaxial cabling. As the wiper printed circuit board220moves, an electrical path length from the input pad230of phase shifter202to each radiating element130served by the transmission lines212,214changes. For example, as the wiper printed circuit board220moves to the left it shortens the electrical length of the path from the input pad230to the output pad240connected to the left side of transmission line trace212(which connects to a first radiating element130), while the electrical length from the input pad230to the output pad240connected to the right side of transmission line trace212(which connects to a second radiating element) increases by a corresponding amount. These changes in path lengths result in phase shifts to the signals received at the output pads240connected to transmission line trace212relative to, for example, the output pad240connected to transmission line trace216.

The second phase shifter202amay be identical to the first phase shifter202. As shown inFIG. 3, the rotating wiper printed circuit board220aof phase shifter202amay be controlled by the same linkage shaft228as the rotating wiper printed circuit board220of phase shifter202. For example, if a linear array120includes dual polarized radiating elements130, typically the same phase shift will be applied to the RF signals transmitted at each of the two orthogonal polarizations. In this case, a single mechanical linkage226may be used to control the positions of the wiper printed circuit boards220,220aon both phase shifters202,202a. In other cases, the wiper printed circuit boards220,220aof the two phase shifters202,202amay be connected to separate linkage shafts228.

As noted above, various physical and/or electrical settings of a RET antenna such as antenna100including the elevation angle can be controlled from a remote location by transmitting control signals to the antenna100that cause electromechanical actuators to adjust the settings on the electro-mechanical phase shifters150. Conventionally, a separate actuator was provided for each phase shifter150(or for a pair of phase shifters150associated with cross-polarized radiating elements130). As discussed above, more recently multi-RET actuators have been suggested that may be used to control a plurality of different phase shifters. These multi-RET actuators use a first “drive” motor to drive the mechanical linkages and a second “indexing” motor to selectively connect one of the mechanical linkages to the first drive motor.

Pursuant to embodiments of the present invention, multi-RET actuator assemblies are provided that include a single motor that actuates multiple mechanical linkages. By eliminating one of the two motors from the above-discussed multi-RET actuator, the size, cost and weight of the multi-RET actuator assembly may be significantly reduced.FIGS. 4A-4Eillustrate a single motor multi-RET actuator assembly300according to embodiments of the present invention. In particular,FIG. 4Ais a perspective view of the single motor multi-RET actuator30Q,FIGS. 4B and 4Care a front perspective view and a side view, respectively, of the single motor multi-RET actuator300with the housing removed therefrom, andFIGS. 4D and 4Eare partial perspective and side views of the single motor multi-RET actuator300with the housing removed that illustrate how one of a plurality of secondary drive gears may be selectively connected to a primary drive gear.

As shown inFIG. 4A, the multi-RET actuator assembly300includes a housing310having a pair of connectors320mounted on one end wall312of the housing310. The housing310may be formed of any appropriate material, such as a metal or polymeric material. The housing310may be omitted in some embodiments. The connectors320may be mounted on a printed circuit board (not shown) in some embodiments. Each connector320may extend through a respective aperture314in the end wall312. The connectors320may connect to communications cables that may be used to deliver control signals from a base station control system to the multi-RET actuator assembly300.

Referring now toFIGS. 4B-4E, an actuator330is mounted within the housing behind the end wall312. The actuator330includes a pair of circular base plates332,334that are mounted within the housing310. A third base plate336may be provided at the distal end of the actuator330. Six generally parallel worm gear shafts340are provided that extend along respective axes R1-R6between base plates334and336(seeFIG. 4D). Each worm gear shaft340includes a worm gear extension342that extends through the base plate334so that each worm gear shaft340is rotatably mounted in the base plate334. The worm gear shafts340are distributed generally circumferentially equidistant from each other. The worm gear extensions342may be formed integrally with their corresponding worm gear shafts340. Respective secondary drive gears344are axially aligned with the worm gear extensions342. Each worm gear extension342may extend partially into an internal cavity347of its respective secondary drive gear344. In some embodiments, each worm gear extension342may extend into the internal cavity347of its respective secondary drive gear344when the secondary drive gear344is in its resting (disengaged) position. In other embodiments, the worm gear extension342may only extend into the internal cavity347of its respective secondary drive gear344when the secondary drive gear344is in its engaged position. Each internal cavity347extends deeper into the secondary drive gear344than necessary to receive the worm gear extension342of its mating worm gear shaft340, which allows each secondary drive gear344to move axially towards its respective worm gear shaft340, in the manner discussed below. A rear portion345of each secondary drive gear344is mounted in a respective opening in the base plate332so that each secondary drive gear344is held in place on the worm gear extension342of its respective worm gear shaft340.

A spring346is mounted on the worm gear extension342of each worm gear shaft340between the base plate334and the respective secondary drive gears344. Each secondary drive gear344may move axially along its respective worm gear extension342between the base plates332,334relative to its associated worm gear shaft340, and may also rotate in concert with its associated worm gear shaft340, at least when the secondary drive gear344is in its engaged position. The springs346bias the secondary drive gears344toward base plate332and away from base plate334, such that a gap exists between each secondary drive gear344and the base plate334. The spring loading of the secondary drive gears344by the springs346may assist in returning the secondary drive gears344to their resting (disengaged) positions after the secondary drive gears344are moved into their engaged positions in the manner discussed below.

A piston350is mounted on each worm gear shaft340. Each piston350may be connected to one end of a respective mechanical linkage (not shown). The mechanical linkage may prevent each piston350from rotating in response to rotation of its respective worm gear shaft340. Each piston350may be internally threaded to mate with the external threads on its corresponding worm gear shaft340. Each piston350may thus be configured to move axially relative to its associated worm gear shaft340along its respective axis R1-R6upon rotation of the worm gear shaft340. The far end of each mechanical linkage may be connected to a wiper arm of a phase shifter or a pair of phase shifters as is discussed above with reference toFIG. 3. Consequently, rotation of a worm gear shaft340may result in axial movement of the piston350mounted thereon, and this axial movement is transferred via the mechanical linkage226to a phase shifter in order to rotate a wiper arm of the phase shifter.

A motor360is mounted forward of the base plate332. A drive shaft362extends from the motor360. The motor360may be used to turn the drive shaft362to rotate about an eccentric axis R7. A primary drive gear364is mounted on the drive shaft362and may be formed integrally with the drive shaft362in some embodiments. The primary drive gear364is positioned in the center of a circle defined by the worm gear shafts340, and is axially offset along axis R7from the secondary drive gears344that are mounted on the respective worm gear extensions342. As will be discussed in detail below, one or more of the secondary drive gears344may be moved axially to engage the primary drive gear364, so that rotation of the primary drive gear364causes each such engaged secondary drive gear344to rotate, which in turn rotates the associated worm gear shafts340, thereby resulting in axial movement of the pistons350. Herein, when a particular secondary drive gear344is engaged with the primary drive gear364, the worm gear shaft340that the secondary drive gear344that is associated therewith is said to be “selected.” The primary drive gear364may be rotated in a first direction (e.g., clockwise) to move the pistons350on any selected worm gear shaft340away from the motor360, and may be rotated in a second direction (e.g., counter-clockwise) to move the pistons350on any selected worm gear shaft340toward the motor360. In this fashion, the rotational movement of the drive shaft362may be transformed into axial movement by one or more of the pistons350.

As is further shown inFIGS. 4B-4Ea magnet370and an electromagnet372may be mounted on (or adjacent) each worm gear extension342, on opposite sides of the springs346. An electromagnet refers to a magnet whose strength may be adjusted by application of an electric control signal. The polarity of an electromagnet may be reversed by reversing the polarity of the control signal. In an example embodiment, the electromagnets372may be connected to the secondary drive gears344and the magnets370may be connected to the base plate334. An electric control signal may be applied to a selected one of the electromagnets372in response to a control signal in order to increase the strength of the “selected” electromagnet372. As the magnetic strength is increased, the electromagnet372may be strongly attracted to its associated magnet370, thereby pulling the “selected” secondary drive gear344toward the base plate334(and compressing the spring346) so that the secondary drive gear344engages the primary drive gear364. The remaining secondary drive gears344may remain in their “resting” (disengaged) positions and hence are spaced apart from the primary drive gear364, and therefore are not in position to drive any of the worm gear shafts340.

As noted above, an internal cavity347is provided in the rear portion345of each secondary drive gear344. As the secondary drive gear344moves axially toward the base plate334in response to the electromagnet force, the worm gear extension342is received within this internal cavity347. The cross-sectional shape of the internal cavity347may be the same as the cross-sectional shape of the portion of the worm gear extension342that is received therein (with the cross-sectional area of the worm gear extension342being slightly smaller so that the worm gear extension342may be received within the internal cavity347). Accordingly, rotation of the secondary drive gear344will result in rotation of the worm gear extension342, which in turn causes rotation of the worm gear shaft340.

FIGS. 4B and 4Cillustrate the default position for the actuator330where none of the secondary drive gears344are engaged with the primary drive gear364.FIGS. 4D and 4Eillustrate the positions of the gears when one of the six secondary drive gears344is engaged with the primary drive gear364. Notably, since the electromagnets372can be controlled independently, any number of the secondary drive gears344may be engaged with the primary drive gear364at the same time. This may allow phase shifts to be implemented more quickly.

Upon receiving a signal from a controller that a phase shift in the antenna is desired, the motor360may be activated to rotate the primary drive gear364about the axis R7. Rotation of the primary drive gear364rotates the engaged secondary drive gear344about its respective axis (in the example ofFIGS. 4D-4E, axis R6), which in turn rotates the worm gear shaft340associated with the secondary drive gear344about the axis R6. Rotation of the worm gear shaft340drives the piston350axially along its associated worm gear shaft340until the piston350reaches a desired position, at which point the motor360deactivates.

Notably, the actuator assembly300is capable of adjusting up to six phase shifters150, which is a typical number for a base station antenna, which often include two high band arrays and one low band array, with each array having a transmit phase shifter and a receive phase shifter for each of two polarizations, for a total of four phase shifters per linear array or twelve phase shifters total. Since a single RET actuator may control both polarizations, a total of six RET actuators are required for such an antenna.

It will be appreciated that numerous modifications may be made to the actuator assembly300. For example, the one or more of the pistons350may be replaced by another axially-drivable member. The primary drive gear364may be any type of central drive gear, or even another variety of a central drive member, such as a wheel or disc that frictionally engages the secondary drive gears344. Similarly, the secondary drive gears344may be replaced with another rotary member, such as a wheel or disc that engages the primary drive member364. The number of worm gear shafts340(and associated structures) may be increased or decreased from six as appropriate depending upon the number of phase shifters that need to be controlled. Numerous other modifications are possible.

FIGS. 5A-5E, 6 and 7illustrate single motor multi-RET actuators according to further embodiments of the present invention.

FIG. 5Ais a schematic block diagram of a portion of a single motor multi-RET actuator400that is similar to the single motor multi-RET actuator330that is discussed above with reference toFIGS. 4A-4E. However, in the multi-RET actuator400, the positions of one or more of the electromagnets372and the permanent magnets370are reversed. This is shown schematically inFIG. 5A, which uses a block diagram format to illustrate the base plates332,334, the drive shaft362with the primary drive gear364mounted thereon, one of the worm gear shafts340with a secondary drive gear344mounted on the extension342thereof. Various other elements of the multi-RET actuator400are not depicted inFIG. 5Asuch as the other worm gears340and their associated secondary drive gears344and springs346, the motor360, the pistons350, etc. in order to simplify the drawing. The multi-RET actuator400may move a selected one of the secondary drive gears344into an engagement with the primary drive gear364by applying a control signal to the electromagnet372that increases the magnetism of the electromagnet372in order to attract the permanent magnet370toward the electromagnet372, thereby moving a selected one of the secondary drive gears344into engagement with the primary drive gear364.

It will also be appreciated that the electromagnet372may be configured to repel the permanent magnet370by switching the polarity of the control signal supplied to the electromagnet. When a repelling force is used as opposed to an attractive force, the configuration of the electromagnet372, the permanent magnet370and each secondary drive gear344may be changed.FIGS. 5B and 5Care schematic block diagrams of a portion of a single motor multi-RET actuator500according to still further embodiments of the present invention that illustrate how a repelling force may be used in other embodiments of the present invention.

As shown inFIG. 5B, the multi-RET actuator500may be similar to the multi-RET actuator400, except that the electromagnet372and the permanent magnet370are moved to the other side of the secondary drive gear344. The permanent magnet370may be mounted on or otherwise connected to the secondary drive gear344so that axial movement of the permanent magnet370results in axial movement of the secondary drive gear344. The spring346may bias the permanent magnet370(and hence the secondary drive gear344) toward the electromagnet372. As shown inFIG. 5B, in this position, the secondary drive gear344is disengaged from the primary drive gear364. When a control signal is applied to the electromagnet372, a magnetism of the electromagnet372may be greatly increased. The electromagnet372is oriented so that the magnetic force repels the permanent magnet370. This repulsive magnetic force may exceed the counter-acting bias force applied by the spring346, and hence, as shown inFIG. 5C, when the electromagnet372is activated by the control signal, the secondary drive gear344is moved into engagement with the primary drive gear364so that rotational movement of the primary drive gear364results in rotational movement of the secondary drive gear344(and hence rotation of the worm gear shaft340).

FIG. 5Dis a schematic block diagram of a single motor multi-RET actuator600that is very similar to the multi-RET actuator500, with the only difference being that the permanent magnet370has been moved to the other side of the secondary drive gear344. The multi-RET actuator600may operate identically to the multi-RET actuator500, but this modified embodiment is depicted to make clear that the positions of the electromagnet372and/or the permanent magnet370may be changed without materially effecting operation of the device. It will also be appreciated that if the secondary drive gear344(or something attached thereto) is formed of a ferromagnetic material, the permanent magnet370may be omitted in any of the embodiments disclosed herein. Alternatively, the permanent magnets370in any of the embodiments disclosed herein may be replaced with a structure that is formed of or includes a ferromagnetic material that is attracted (or repelled, depending upon the orientation) from the electromagnet372when the electromagnet is activated. The ferromagnetic structure may have the same shape as the permanent magnet370or may have a different shape. The use of such ferromagnetic materials may be advantageous in some embodiments as it may reduce or eliminate any crosstalk between magnets that are in close proximity to each other, and also will reduce the possibility that other structures in the actuator are unintentionally magnetized such as the lead screw.

FIG. 5Eis a schematic block diagram of a single motor multi-RET actuator700that is very similar to the multi-RET actuator600ofFIG. 5D, with the only difference being that an additional electromagnet372is provided adjacent the base plate334. The two electromagnets372are labelled372-1and372-2for ease of description of this embodiment. The electromagnet372-1may impart a repulsive force on the permanent magnet370in response to a control signal, while the electromagnet372-2may impart an attractive force on the permanent magnet370so that the two electromagnets372-1,372-2work together to overcome the bias force of the spring346that is mounted on the worm gear extension342in order to move the secondary gear344into engagement with the primary drive gear364.

In the above-described embodiments, electromagnets are provided that are used to selectively move one or more of the secondary drive gears344into engagement with the primary drive gear364. Pursuant to further embodiments of the present invention, the primary drive gear364may instead be moved into engagement with a selected one of the secondary drive gears344.FIG. 6is a schematic block diagram of a single motor multi-RET actuator800according to embodiments of the present invention in which the primary drive gear364is moved as opposed to the secondary drive gears344. To simplify the figure, only two of the worm gear shafts340and their associated extensions342and secondary drive gears344are illustrated inFIG. 6. It will be appreciated, that more than two worm gear shafts340and their associated elements may be provided. As shown inFIG. 6, the two secondary drive gears344are axially offset from each other so that when the primary drive gear364is engaged with one of the secondary drive gears344it is not engaged with the other of the secondary drive gears344. If more than two secondary drive gears344are provided, the additional secondary drive gears344may likewise be axially offset from each of the other secondary drive gears344.

As shown inFIG. 6, the electromagnet372is mounted on the primary drive gear364while the permanent magnet370is mounted on or adjacent the base plate334. A control signal may be applied to the electromagnet372to increase the magnetism thereof so that the electromagnet372is attracted to the permanent magnet370, thereby pulling the electromagnet372(and the primary drive gear364) axially along the drive shaft362. The drive shaft362may, for example, have a transverse cross-section that is non-circular such as, for example, a square transverse cross-section. This may allow the primary drive gear364to move axially along the drive shaft362while also ensuring that rotation of the drive shaft362will result in rotation of the primary drive gear364. Different control signals may be used depending upon which of the secondary drive gears344is to be selected. For example, if the primary drive gear364is to engage the secondary drive gear344-1, then the electromagnet372may be caused to exhibit a first level of electromagnetic force that is sufficient to move the primary drive gear364to compress the spring366a first amount so that the primary drive gear364engages secondary drive gear344-1. If the primary drive gear364is to engage the secondary drive gear344-2, then the electromagnet372may be caused to exhibit a second, greater, level of electromagnetic force that is sufficient to move the primary drive gear364to compress the spring366a second amount so that the primary drive gear364engages secondary drive gear344-2. The secondary drive gears344may be offset by axial amounts that are sufficient so that variation in the attraction force between the electromagnet372and the permanent magnet370and or variation in the bias force of the spring366that may occur over time due to aging of components or due to other magnetic, friction or other forces is sufficient so that the primary drive gear364will always engage the selected one of the secondary drive gears344.

In the embodiment ofFIG. 6, it may be necessary for the primary drive gear364to move a greater distance, particularly if the multi-RET actuator800includes a relatively large number of secondary drive gears344(e.g.,6). This may require the use of a more powerful electromagnet372and/or a more powerful permanent magnet370. Additionally, the technique described above where two electromagnets372may also be used. It will also be appreciated that the positions of the electromagnets372and the permanent magnets370may be varied in the manner discussed above with reference toFIGS. 5A-5Ein the embodiment ofFIG. 6.

FIG. 7is a schematic block diagram of a single motor multi-RET actuator900according to further embodiments of the present invention that has a primary drive gear364that may be moved in two different directions along the drive shaft362in order to reduce the amount of electromagnetic force that may be necessary in operation.

As shown inFIG. 7, the single motor multi-RET actuator900is similar to the single motor multi-RET actuator800ofFIG. 6, except that the multi-RET actuator900includes an additional spring366(the two springs are labeled366-1and366-2inFIG. 7), an additional electromagnet372(the two electromagnets are labeled372-1and372-2inFIG. 7) and an additional permanent magnet370(the two permanent magnets are labeled370-1and370-2inFIG. 7). InFIG. 7, the multi-RET actuator is illustrated as including a total of six worm gear shafts340and associated elements (e.g., secondary drive gears344) to better illustrate the operation thereof. Note that only four of the worm gear shafts340and worm gear extensions342are visible inFIG. 7because of the side view, although the secondary drive gears344that are associated with the hidden worm gear shafts340are visible. It will be appreciated that the multi-RET actuator900may include a different number of worm gear shafts340.

In its resting position, the primary drive gear364may be axially located at approximately a midpoint between the base plates332,334. As shown inFIG. 7, three of the secondary drive gears344are located axially to the left of the midpoint, while the other of the secondary drive gears344are located axially to the right of the midpoint. A spring366-1is mounted on the drive shaft362to the right of the midpoint, and a spring366-2is located on the drive shaft362to the left of the midpoint. The electromagnets372-1,372-2are mounted on the primary drive gear364while the permanent magnets370-1,370-2are mounted at the far ends of the respective springs366-1,366-2from the primary drive gear364.

If, for example, a phase shifter attached via a mechanical linkage to a worm gear shaft340associated with one of the secondary drive gears344that is to the left of the midpoint needs adjustment, a controller (not shown) may send a control signal to the electromagnet372-2to increase the attractive force between electromagnet372-2and permanent magnet370-2. As a result, the primary drive gear364may move to the left, compressing spring366-2to a degree, so that the primary drive gear364engages the desired secondary drive gear344. If instead a phase shifter attached via a mechanical linkage to the worm gear shaft340associated with one of the secondary drive gears344that are to the right of the midpoint needs adjustment, then electromagnet372-1may be supplied a control signal so that a magnetic force is generated that moves the primary drive gear364to the right to engage the desired secondary drive gear344, which is the situation shown inFIG. 7. In each of the above cases, both electromagnets372-1and372-2may be used to move the primary drive gear364by controlling one of the electromagnets372to generate an attractive magnetic force and the other to generate a repelling magnetic force in a manner similar to the discussion of the embodiment ofFIG. 5Eabove.

While electromagnetic force provides one mechanism for moving the primary drive gear364into engagement with a selected one of the secondary drive gears344, or vice versa, it will be appreciated that embodiments of the present invention are not limited to the use of such electromagnetic forces. Instead, embodiments of the present invention extend to any mechanical force that may be applied in response to a control signal. For example,FIG. 8is a schematic block diagram of a single motor multi-RET actuator1000according to still further embodiments of the present invention that uses a piezoelectric actuator to connect a selected mechanical linkage to a motor.

As shown inFIG. 8, the multi-RET actuator1000may be similar to the multi-RET actuator400ofFIG. 5A, except that the electromagnet372and permanent magnet370are replaced with a piezoelectric actuator380. Piezoelectric actuators are known in the art and use the piezoelectric effect to effect a physical movement. The piezoelectric effect refers to an electric charge that may accumulate in certain solid materials such as crystals in response to applied mechanical stress. The piezoelectric effect is thus a linear electromechanical interaction between the mechanical and the electrical state in crystalline materials. The piezoelectric effect is a reversible process in that materials exhibiting the direct piezoelectric effect (the internal generation of electrical charge resulting from an applied mechanical force) also exhibit the reverse piezoelectric effect (the internal generation of a mechanical strain resulting from an applied electrical field). Piezoelectric actuators apply an electrical field to generate a mechanical strain.

A separate piezoelectric actuator380may be provided for each of the secondary drive gears344and may be configured to move the respective secondary drive gears344into engagement with the primary drive gear364in response to respective control signals. While only one embodiment of the present invention is illustrated in the figures that includes a piezoelectric actuator380, it will be appreciated that the electromagnets/permanent magnets372/370of each of the other embodiments disclosed herein may be replaced with piezoelectric actuators to provide a plurality of additional embodiments.

Piezoelectric actuators tend to only provide a small amount of physical, mechanical movement (often referred to as “stroke”), which can be a limitation in some applications. For example, a typical piezoelectric material may only provide 0.1% strain, meaning that a 1 meter piece of piezoelectric material may be required to obtain a stroke of 1 mm. Amplified piezoelectric actuators may be used to mitigate this limitation in some embodiments.

It will be appreciated that numerous modifications may be made to the above-described example embodiments without departing from the scope of the present invention. As one example, the above described embodiments implement the primary drive gear as a central gear and the secondary drive gears as gears that circumferentially surround the central primary drive gear. It will be appreciated that in other embodiments the secondary drive gears may only partially circumferentially surround a central primary drive gear, or that the drive gears may have a different arrangement such as the secondary drive gears being linearly arranged. In such an embodiment the central drive gear could move to engage a respective one of the secondary drive gears or an intermediate gear that is engaged with the primary drive gear could move to engage a selected on of the secondary drive gears. Numerous other arrangements are possible. In each case an electromagnetic engagement mechanism and/or a piezoelectric engagement mechanism may be used to move one or more of the gears so that the primary drive gear may rotate a selected one (or more) of the secondary drive gears.

Pursuant to further embodiments of the present invention, multi-RET actuator assemblies are provided that include a main motor and a plurality of small “micro-motors” that are used together to, for example, serially actuate multiple mechanical linkages. While these multi-RET assemblies increase the total number of motors used, the six micro-motors may be less expensive than a single conventional motor, and the micro-motors may be highly reliable and hence may involve less risk of failure in the field as compared to some other options.FIGS. 9A-9Eillustrate a multi-RET actuator1130that may be used as part of such a multi-RET actuator assembly. WhileFIGS. 9A-9Eonly depict the multi-RET actuator1130, it will be appreciated that the multi-RET actuator may be incorporated, for example, into the multi-RET actuator assembly300ofFIG. 4Ain place of the multi-RET actuator330.

Referring now to the figures,FIG. 9Ais a side view of the multi-RET actuator1130,FIG. 9Bis an enlarged, partial side view of the multi-RET actuator1130with one of the secondary drive gears thereof engaged with the primary drive gear,FIG. 9Cis a partial side sectional view of the multi-RET actuator1130,FIG. 9Dis a partial side perspective view of the multi-RET actuator1130with none of the secondary drive gears engaged with the primary drive gear, andFIG. 9Eis a partial side perspective view of the multi-RET actuator1130with one of the secondary drive gears engaged with the primary drive gear.

Referring first toFIGS. 9A, 9C and 9D, the multi-RET actuator1130includes a pair of circular base plates1132,1134that may be mounted within a housing (not shown) of the multi-RET actuator assembly (e.g., within housing310of multi-RET actuator assembly300). A third base plate1136is provided at the distal end of the actuator1130. The base plates1132,1134,1136may be identical to the base plates332,334,336of multi-RET actuator330and hence further description thereof will be omitted herein. Six generally parallel worm gear shafts1140are provided that extend along respective generally parallel axes between base plates1134and1136. Each worm gear shaft1140includes a worm gear extension1142that is rotatably mounted in the base plate1134. A secondary drive gear1144is axially aligned with each worm gear extension1142. As shown best inFIG. 9C, each worm gear extension1142may extend partially into an internal cavity1147of its associated secondary drive gear1144. Each internal cavity1147extends deeper into the secondary drive gear1144than necessary to receive the worm gear extension1142of its mating worm gear shaft1140, which allows each secondary drive gear1144to move axially towards its associated worm gear shaft1140. A rod-like rear portion of each secondary drive gear1144is mounted in a respective opening in the base plate1132. A spring1146is mounted on each worm gear extension1142. Each secondary drive gear1144may move axially along its respective worm gear extension1142, and may also rotate in concert with its associated worm gear shaft1140when the secondary drive gear1144is in its engaged position so that it engages the primary drive gear1164. The springs1146bias the secondary drive gears1144toward base plate1132. The worm gear shafts1140, worm gear extensions1142, secondary drive gears1144and springs1146may be identical to the corresponding worm gear shafts340, worm gear extensions342, secondary drive gears344and springs346of multi-RET actuator330and hence further description thereof will be omitted herein.

An internally threaded piston1150is mounted on each externally threaded worm gear shaft1140. Each piston1150may be connected to a respective mechanical linkage (not shown). When a selected one of the worm gear shafts1140is rotated, the mechanical linkage that is connected to the piston1150that is mounted on the selected worm gear shaft1140prevents the piston1150from rotating. As the externally threaded worm gear shaft1140rotates, the piston1150moves axially relative to the worm gear shaft1140along the axis of rotation of the worm gear shaft1140, which in turn imparts the same axial movement to the mechanical linkage that is connected to the piston1150. The far end of each mechanical linkage may be connected to a phase shifter or a pair of phase shifters such as the phase shifters ofFIG. 3. Thus, rotation of a worm gear shaft1140may impart axial movement to the piston1150and its associated mechanical linkage226that is used to rotate a wiper arm of a phase shifter.

A main motor1160is mounted forward of the base plate1132. A drive shaft1162extends from the main motor160. The main motor1160may be used to rotate the drive shaft1162. A primary drive gear1164is mounted on the drive shaft1162and may be formed integrally with the drive shaft1162. The primary drive gear1164is positioned in the center of a circle defined by the worm gear shafts1140, and is axially offset from the secondary drive gears1144. The secondary drive gears1144may be moved axially to engage the primary drive gear1164, so that rotation of the primary drive gear1164rotates each engaged secondary drive gear1144, which in turn rotates the associated worm gear shafts1140, thereby resulting in axial movement of the pistons1150.

As is further shown inFIGS. 9A, 9C and 9Da micro-motor1170is mounted on each of the secondary drive gears1144forwardly of base plate1132. The micro-motors1170may be small and relatively inexpensive. Each micro-motor1170has an associated externally threaded drive shaft1172that rotates when its associated micro-motor1170is activated. The drive shafts1172may be rotated clockwise or counter-clockwise by the micro-motors1170. An internally threaded piston1174is mounted on each externally threaded drive shaft1172. A rear end of each piston1174is attached to a front portion of a respective one of the secondary drive gears1144. When one of the micro-motors1170rotates in, for example, the clockwise direction, the piston1174mounted thereon moves rearwardly along the axis of the drive shaft1172. This can best be seen inFIG. 9C, where the piston1174-1is shown in its retracted position while piston1174-2has been moved rearwardly into an extended position by activation of micro-motor1170-2. As piston1174-2moves rearwardly, it pushes secondary drive gear1144-2rearwardly as well, compressing the spring1146-2, so that the geared portion of secondary drive gear1144-2engages the primary drive gear1164. As the secondary drive gear1144-2is pushed axially toward the base plate1134by the micro-motor1170-2, the worm gear extension1142-2is received within the internal cavity1147in secondary drive gear1144-2. The remaining secondary drive gears1144may remain in their “resting” (disengaged) positions and hence are spaced apart from the primary drive gear1164.

Upon receiving a signal from a controller that a phase shift in the antenna is desired, the motor1160may be activated to rotate the primary drive gear1164. Rotation of the primary drive gear1164rotates the engaged secondary drive gear1144-2about its respective axis. The cross-sectional shape of the internal cavity1147may be the same as the cross-sectional shape of the portion of the worm gear extension1142-2that is received therein so that rotation of the selected secondary drive gear1144-2by the primary drive gear1164results in rotation of the worm gear extension1142-2, which in turn causes rotation of the worm gear shaft1140-2. Rotation of the worm gear shaft1140-2drives the piston1150mounted thereon axially until it reaches a desired position, at which point the motor1160is deactivated.

It should be noted that multiple of the secondary drive gears1144may be moved into their engaged positions at the same time so that the main drive gear1164may move multiple of the pistons1150simultaneously. This may allow phase shifts to be implemented more quickly.

FIGS. 9A and 9Dillustrate the default position for the multi-RET actuator1130where none of the secondary drive gears1144are engaged with the primary drive gear1164.FIGS. 9B, 9C and 9Eillustrate the positions of the gears when one of the six secondary drive gears1144is engaged with the primary drive gear1164.

It will be appreciated that numerous modifications may be made to the multi-RET actuator1130, including the modifications discussed above with respect to multi-RET actuator330.

Pursuant to yet additional embodiments of the present invention, multi-RET actuator assemblies are provided that use a drive motor and a stepper motor to actuate multiple mechanical linkages. Examples of such embodiments are depicted inFIGS. 10A-10F. In particular,FIG. 10Ais perspective view of a multi-RET actuator assembly1200according to further embodiments of the invention.FIG. 10Bis a perspective view of the multi-RET actuator1200with the housing removed therefrom.FIG. 10Cis a perspective view of a multi-RET actuator1230that is included in the multi-RET actuator assembly1200ofFIGS. 10A-10B. FIG.10D is a perspective view of the multi-RET actuator1230with the motors, cam plate and one base plate removed.FIG. 10Eis a side view of the multi-RET actuator1230.FIG. 10Fis another perspective view of the actuator1230with the motors, cam plate and one base plate removed.

The multi-RET actuator assembly1200is shown inFIG. 10A. The actuator assembly1200includes a housing1210with a pair of connectors1220mounted on one end wall1212thereof and a multi-RET actuator1230is mounted within the housing1210. The housing1210may be formed of any appropriate material, such as a metal or polymeric material.

Referring toFIG. 10B, the connectors1220may be mounted on a printed circuit board1222in some embodiments. The circuit board1222is mounted next to the end wall1212so that the connectors1220extend through the end wall1212. The connectors1220may connect to communications cables that may be used to deliver control signals from a base station control system to the multi-RET actuator assembly1200.

Referring now toFIGS. 10B-10F, the actuator1230includes a pair of circular base plates1232,1234that are mounted within the housing1210. A third base plate1236may be provided at the distal end of the assembly1200. Six generally parallel worm gear shafts1240are provided that extend along respective axes between base plates1234and1236. The worm gear shafts1240are distributed generally circumferentially equidistant from each other.

Each worm gear shaft1240has a worm gear extension1242extending from the forward end thereof through base plate1234. Each worm gear extension1242may be formed integrally with its corresponding worm gear shaft1240. Each worm gear shaft1240and its corresponding worm gear extension1242are rotatably mounted in the base plate1234. A selector gear1244is mounted axially on each work gear extension1242so that each worm gear extension extends axially into an internal cavity within the selector gear1244. A spring1246is mounted on each worm gear extension between the base plate1234and the selector gear1244. Each spring1246biases its associated selector gear1244away from the base plate1234and toward base plate1232, such that a gap exists between each selector gear1244and the base plate1234. The spring loading of the selector gears1244by the springs1246may assist in returning the selector gears1244to their resting (disengaged) positions after the selector gears1244are moved into their engaged positions in the manner discussed below

Each selector gear1244is mounted onto its respective worm gear extension1242so that the selector gear1244can move axially between the base plates1232,1234relative to the worm gear extension1242. The end of each worm gear extension1242may have a cross-section that corresponds to the cross-section of the internal cavity of its corresponding selector gear1244so that rotation of the selector gear1244causes corresponding rotation of the worm gear extension1242and the worm gear shaft1240that the worm gear extension1242extends from.

A piston1250is mounted on each worm gear shaft1240and is configured (e.g., via threads) to move axially relative to the worm gear shaft1240along its respective axis upon rotation of the worm gear shaft1240. Each piston1250is connected to a mechanical linkage (not shown) that associates the piston1250with one or more phase shifters of an antenna, such that axial movement of the piston1250can cause at least one phase shift in the antenna. For example, axial movement of the piston1250can be used to move the wiper arm of the phase shifter150ofFIG. 3.

Referring now toFIGS. 10B-10D, a ringed cam plate1270is mounted forwardly and spaced apart from base plate1232. The cam plate1270has a nubbed cam1272that extends toward the base plate1232. A ring gear1274with teeth on its inner diameter extends axially from the cam plate1270and is positioned for rotation about a central axis that extends generally in parallel and in the center of the axes defined by the worm gear shafts1240. A cam plate drive motor1276is eccentrically mounted to rotate about an eccentric axis R; a gear (not shown) on a shaft (not shown) attached to the cam plate drive motor1276engages the teeth of the ring gear1274.

Referring again toFIGS. 10B-10F, a stepper gear motor1260is mounted collinearly with the ring gear1274forward of the base plate1232. A stepper gear1264is mounted to a drive shaft1262of the stepper gear motor1260and is positioned adjacent the base plate1232for rotation about the central axis. The stepper gear1264may be formed integrally with the drive shaft1262. The stepper gear1264is positioned in the center of a circle defined by the worm gear shafts1240, and is axially offset from the stepper gears1244that are mounted on the respective worm gear extensions1242when the stepper gears1244are in their resting (disengaged) positions. The stepper gear1264is sized so that its teeth can engage the teeth of a selector gear1244when the selector gear1244is in position adjacent the base plate1234.

In operation, the cam plate1270is rotated about the central axis to an orientation in which the cam1272is positioned between the forward ends of two the selector gears1244. When the cam1272is in this position, all of the selector gears1244are positioned to be spaced from the base plate1234. Accordingly, all of the selector gears1244are disengaged from the stepper gear1264, and therefore are not in position to drive any of the worm gear shafts1240. As such, in this disengaged position, all of the pistons1250remain in place on their respective worm gear shafts1240.

Upon a signal from a controller that a phase shift in the antenna is desired, the cam plate drive motor1276is activated and begins to rotate the cam plate1270about the central axis through interaction between the gear of the cam plate drive motor1276and the teeth of the ring gear1274. As the cam plate1270rotates about the central axis, the cam1272serially engages each of the forward ends of the stepper gears1244and forces them toward the base plate1234and into position for engagement with the stepper gear1264. Continued rotation of the cam plate1270about the central axis moves the cam1272past the forward end of a respective one of the selector gears1244, allowing the spring loading of the selector gear1244to return the selector gear1244to its rest position.

When the cam1272reaches the forward end of the selector gear1244associated with the piston1250that is to be moved to induce the phase shift in the antenna, the cam plate drive motor1276ceases to move, thereby allowing cam1272to remain in engagement with the forward end of the selector gear1244. Engagement of the forward end of the selector gear1244by the cam1272moves the selector gear1244rearwardly toward the base plate1234and into engagement with the stepper gear1264(this is shown inFIGS. 10D and 10F). The stepper gear motor1260then activates and rotates the stepper gear1264about the central axis. Rotation of the stepper gear1264rotates the engaged selector gear1244about its respective axis, which in turn rotates the worm gear shaft1240associated with the selector gear1244about the axis of the worm gear shaft1240. Rotation of the worm gear shaft1240drives the piston1250axially along the worm gear shaft1240until the piston1250reaches a desired position, at which point the stepper gear motor1260deactivates. The cam plate1270can either remain in position or move to a rest position to await the next phase shift instruction. The stepper gear1264may be rotated in a first direction (e.g., clockwise) to move the pistons1250on any selected worm gear shaft1240away from the stepper motor1260, and may be rotated in a second direction (e.g., counter-clockwise) to move the pistons1250on any selected worm gear shaft1240toward the stepper motor1260.

The actuator1230is capable of adjusting up to six mechanical linkages via the six pistons1250, each of which controls one or more phase shifters. In other embodiments, more or fewer linkages may be included.

Those of skill in this art will recognize that other variations of the actuator123Q may be employed. For example, the pistons1250may be replaced by another axially-drivable member. The stepper gear1264may be any type of central drive gear, or even another variety of a central drive member, such as a wheel or disc that frictionally engages the selector gears1244. The selector gears1244may be replaced with another rotary member, such as a wheel or disc that engages the central drive member. The cam plate1270and ring gear1274may be replaced with another engagement mechanism that selectively and exclusively engages one shaft at a time. The cam plate1270may have a recess rather than a cam1272, such that a respective selector gear1244moves toward the base plate1232when the recess rotates in front of the selector gear, with engagement of the selector gear1244or other rotary member with the stepper gear1264occurring at a position spaced apart from, rather than adjacent to, the base plate1234. Drive units other than the stepper gear motor1260and the cam plate drive motor1276may be employed. Other variations may also be apparent to those of skill in this art.

Pursuant to still further embodiments of the present invention, multi-RET actuators are provided that use a single motor and a ratchet-based gear system to actuate multiple mechanical linkages. Examples of such embodiments are depicted inFIGS. 11A-11C. These multi-RET actuators may be similar to the single-motor multi-RET actuator330discussed above with reference toFIGS. 4A-4E, except the electromagnetic system for moving the secondary drive gears included in the multi-RET actuator330is replaced in multi-RET actuator1330with a ratchet based gear system. The ratchet based gear system is similar to the gear system included in the multi-RET actuator1230discussed above, but the use of ratcheted gears eliminates any need for a second motor.

Referring first toFIG. 11A, which is a schematic front view of the multi-RET actuator1330that illustrates various gears thereof, it can be seen that the multi-RET actuator1330includes a plurality of secondary drive gears1344, a forward-direction primary drive gear1364, a reverse direction primary drive gear1366and a reversing gear1368. The multi-RET actuator1330may include circular base plates, worm gear shafts, worm gear extensions, springs and pistons that may be identical in both structure and arrangement to the base plates1132,1134,1136, the worm gear shafts1140, the worm gear extensions1142, the springs1146and the pistons1150of multi-RET actuator1130, and hence further description thereof will be omitted herein.

FIG. 11Bis a schematic top view of the various gears included in multi-RET actuator1330. A portion of one of the six worm gear shafts1340-1and its associated worm gear extension1342-1and spring1346-1are also illustrated inFIG. 11B, as is the circular base plate1334that abuts the forward ends of the worm gear shafts1340.

As shown inFIG. 11B, a drive shaft1362of the single motor (not shown) of multi-RET actuator1330has three gears mounted thereon, namely the forward-direction primary drive gear1364, the reverse direction primary drive gear1366and an indexing gear1374. The forward-direction primary drive gear1364and the reverse direction primary drive gear1366are each ratcheted gears that only rotate in response to clockwise rotation of the drive shaft1362and which do not rotate in response to counter-clockwise rotation of the drive shaft1362. A ringed cam plate1370is provided that may be located in the same position as the cam plate1270of multi-RET actuator1230, and which is similar in design thereto. The ringed cam plate1370includes a circular channel1378on the rear surface thereof (shown in dotted lines inFIG. 11Bwhich illustrates what a cross-section of the cam plate1370would look like), although it will be appreciated that the channel1378may be omitted in other embodiments. The ringed cam plate1370includes a fixed cam plate gear1376on a front surface thereof. The cam plate gear1376is positioned such that it is permanently engaged with the indexing gear1374that is mounted on drive shaft1362. The cam plate1370further includes a nubbed cam1372on its rear surface that extends toward the base plate1334. The cam1372is located in the channel1378so that the cam fills the channel1378and extends out of the channel1378as shown inFIG. 11B.

The cam plate1370is mounted for rotation about a central axis thereof (which may be the axis defined by the drive shaft1362). The indexing gear1374is a ratchet gear that only rotates when the drive shaft rotates in a particular direction. For purposes of the discussion herein, it is assumed that the ratcheted indexing gear1374only rotates when the drive shaft rotates in the counter-clockwise direction, and that the forward-direction primary drive gear1364and the reverse-direction primary drive gear1366only rotate when the drive shaft rotates in the clockwise direction. It will be appreciated, however, that these directions may be reversed in other embodiments.

When the motor1360(not shown) rotates the drive shaft1362in the counter-clockwise direction, the indexing gear1374rotates in the clockwise direction. As noted above, a toothed cam plate gear1376is formed on the cam plate1370. As the indexing gear1374is mounted so that the teeth thereof are in permanent engagement with the teeth of cam plate gear1376, rotation of the indexing gear in the clockwise direction causes counter-clockwise rotation of the cam plate1370(since the cam plate1370is fixed to the cam plate gear1376). Thus, by rotating the drive shaft1362in the counter-clockwise direction it is possible to rotate the cam plate1370in the counter-clockwise direction. The nubbed cam1372on cam plate1370may then be used to “select” one of the secondary drive gears1344in the same manner that the nubbed cam1272may be used to select one of the secondary drive gears1244of multi-RET actuator1230. Accordingly, further description of the operation of cam plate1370and cam1372will be omitted.

As is also shown inFIG. 11B, the reversing gear1368is mounted for rotation on a shaft1369that extends rearwardly from the cam plate1370. The reversing gear1368is axially aligned with each secondary drive gear1344and with the reverse-direction primary drive gear1366(i.e., they are each at the same distance from the circular base plate1334). The reversing gear1368is positioned so that the teeth thereof permanently engage the teeth of the reverse-direction primary drive gear1366, and so that the teeth of the reversing gear1368engage the teeth of each secondary drive gear1344when the reverse-direction primary drive gear1366, the reversing gear1368and the secondary drive gear1344at issue are radially aligned.

The multi-RET actuator1330may operate as follows. In order to move a piston (not shown) that is mounted on a first of the worm gear shafts1340-1in a first direction (which we will assume here is the forward direction toward base plate1334), the motor is activated to move the drive shaft1362in the counter-clockwise direction. As discussed above, this causes the indexing gear1374to rotate in the counter-clockwise direction which, via its interaction with the cam plate gear1376, causes the cam plate1370to rotate in the counter-clockwise direction. The cam plate1370is rotated until the cam1372engages the forward end of secondary drive gear1344-1(i.e., the secondary drive gear that is associated with the piston that is to be moved). As cam1372engages secondary drive gear1344-1, the secondary drive gear is pushed rearwardly so that the toothed section thereof engages for the forward-direction primary drive gear1364. When this occurs, the motor is shut off. The cam plate1370may then be left in place or may be rotated further. When the cam plate1370is further rotated, the cam1372disengages from the selected secondary drive gear1344, and the spring1346associated with the selected secondary drive gear1344pushes the selected secondary drive gear1344back into its resting position.

In order to move the piston in the forward direction, the motor is turned back on in the opposite direction so that the drive shaft1362rotates in the clockwise direction. As discussed above, the indexing gear1374is ratcheted and hence does not rotate in response to the clockwise rotation of the drive shaft1362. However, the forward-direction and reverse-direction primary drive gears1364,1366are oppositely ratcheted, and hence both of these gears1364,1366rotate in the clockwise direction in response to the clockwise rotation of the drive shaft1362.

As the secondary drive gears1344are circumferentially spaced at equal distances, the secondary drive gears1344may be radially spaced apart from each other at 60° intervals. As shown schematically inFIG. 11A, the reversing gear1368and the cam1372may be spaced apart from each other by about 30°. As a result, when the cam1372is used to select one of the secondary drive gears1344in the manner described above, the reversing gear1368may be radially positioned about midway between two of the secondary drive gears1344, and hence is not in contact with any of the secondary drive gears1344.

As the drive shaft1362rotates in the clockwise direction, both the forward-direction primary drive gear1364and the reverse-direction primary drive gear1366rotate in the clockwise direction. The reverse-direction primary drive gear1366rotates the reversing gear1368, but as the reversing gear1368does not engage any of the secondary drive gears1344, this rotation has no effect. The clockwise rotation of the forward-direction primary drive gear1364results in counter-clockwise rotation of the selected secondary drive gear1344-1. The counter-clockwise rotation of the selected secondary drive gear1344-1results in counter-clockwise rotation of the worm gear shaft1340-1, which causes the piston mounted thereon to move in the forward direction toward base plate1334.

In order to move the piston associated with secondary drive gear1344-1in the rearward direction (i.e., away from base plate1334), the motor is activated to move the drive shaft1362in the counter-clockwise direction. As discussed above, this causes the cam plate1370to rotate in the counter-clockwise direction. The cam plate1370is rotated until the reversing gear1368is radially aligned with the selected secondary drive gear1344-1so that the teeth on the reversing gear1368engage the teeth on the reverse-direction drive gear1366and the teeth of the selected secondary drive gear1344-1. Note that when the cam plate1370is rotated to this position, the cam1372is radially positioned between two of the secondary drive gears1344, and hence all six of the secondary drive gears1344remain in their resting positions (i.e., the position shown inFIG. 11B).

Once the reversing gear1368has been rotated to engage the selected secondary drive gear1344-1, the motor reverses direction to rotate the drive shaft1362in the clockwise direction. As the indexing gear1374is ratcheted, it does not rotate in response to the clockwise rotation of the drive shaft1362and hence the cam plate1370remains stationary. The forward-direction and reverse-direction primary drive gears1364,1366rotate in the clockwise direction in response to the clockwise rotation of the drive shaft1362.

As all of the secondary drive gears1344are in their respective resting positions, the rotation of the forward-direction primary drive gear1364does not have any effect. However, the clockwise rotation of the reverse-direction primary drive gear1366results in counter-clockwise rotation of the reversing gear1368, which in turn results in clockwise rotation of the selected secondary drive gear1344-1. The clockwise rotation of the selected secondary drive gear1344-1results in clockwise rotation of the worm gear shaft1340-1, which causes the piston mounted thereon to move in the rearward direction, away from base plate1334. Thus, as described above, the motor in conjunction with the ratcheted gear system described above may be used to select any of the worm gear shafts1340and move a piston mounted thereon in either direction.

FIG. 11Cconceptually illustrates the operation of the drive shaft1362and the ratcheted gears1364,1366,1374attached thereto. Note that to avoid undesired movements of non-selected ones of the secondary drive gears1344when the index gear1374is being moved, the torque of each secondary drive gear1344should be greater than the torque of the reversing gear1368plus the torque of the drive reverse-direction primary drive gear1366.

It should be noted that the forward-direction primary drive gear1364and the reverse-direction primary drive gear1366need only move the pistons1150in opposite directions. The actual direction (i.e., forward or reverse along the worm gear shafts1140) of movement of the pistons is arbitrary.

The multi-RET actuator1330ofFIGS. 11A-11Cmay be viewed as comprising a plurality of shafts (e.g., the worm gear shafts1340and their associated worm gear extensions1342) that have respective axially-drivable members (e.g., the pistons1350) mounted thereon. Each of axially-drivable member may be configured to be connected to a respective one of a plurality of phase shifters. The multi-RET actuator1330further includes a motor1360having a drive shaft1362and a gear system that is configured to selectively couple the motor1360to the respective shafts1340/1342. The gear system is configured so that rotation of the drive shaft1362in a first direction creates a mechanical linkage between the motor1360and a first of the shafts1340/1342, and rotation of the drive shaft1362in a second direction that is opposite the first direction rotates the first of the shafts1340/1342.

The gear system may include a forward-direction primary drive gear1364that is connected to the drive shaft1362and a reverse-direction primary drive gear1366that is connected to the drive shaft1362. The forward-direction primary drive gear1364and the reverse-direction primary drive gear1366are each ratcheted gears that rotate in response to rotation of the drive shaft1362in the second direction and which do not rotate in response to rotation of the drive shaft1362in the first direction. The gear system may further include a reversing gear1368that is configured to engage the reverse-direction primary drive gear1366and rotate in a direction opposite a direction of rotation of the reverse-direction primary drive gear1366. The gear system may also include a plurality of secondary drive members (e.g., the secondary drive gears1344) that are mounted on respective ones of the shafts1340/1342, each secondary drive member1344mounted so that rotation thereof will result in rotation of a respective one of the shafts1340/1342. The gear system may also include an engagement mechanism (e.g., the cam plate1370) that is configured to rotate to selectively and exclusively engage one or more of the shafts1340/1342to move a selected one of the secondary drive members1344into engagement with one of the forward-direction primary drive gear1364or the reversing gear1368.

Pursuant to further embodiments of the present invention, methods of adjusting a phase shifter are provided. These methods may be implemented using, for example, the multi-RET actuator1330ofFIGS. 11A-11C. Pursuant to these methods, a drive shaft (e.g., drive shaft1362) is rotated in a first direction to connect a first of a plurality of gears (e.g., secondary drive gear1344-1) to a drive mechanism. The drive shaft1362is then rotated in a second direction to rotate a gear of the drive mechanism, wherein rotation of the gear of the drive mechanism causes rotation of the first of the plurality of gears1344, and rotation of the first of the plurality of gears1344mechanically adjusts a physical position of a component of the phase shifter.

The plurality of gears may be secondary drive gears1344that are configured to rotate respective shafts such as worm gear shafts1340. The drive mechanism may include a forward-direction primary drive gear1364that is connected to the drive shaft1362and a reverse-direction primary drive gear1366that is connected to the drive shaft1362. The forward-direction primary drive gear1364may be a ratcheted gear that only rotates in response to rotation of the drive shaft in a first direction, and the reverse-direction primary drive gear1366may be a ratcheted gear that only rotates in response to rotation of the drive shaft1362in the first direction. The plurality of gears may further include a reversing gear1368. At least one of the forward-direction primary drive gear1364or the reverse-direction primary drive gear1366may be configured to engage the first of the plurality of gears1344-1through the reversing gear1368.

WhileFIG. 3above depicts a conventional wiper-arc type phase shifter, numerous other types of electromechanical phase shifters are known in the art. It will be appreciated that the actuators disclosed herein are suitable for use with a wide variety of different phase shifters.

The present invention has been described above with reference to the accompanying drawings. The invention is not limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the invention to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.

Herein, the terms “attached”, “connected”, “interconnected”, “contacting”, “mounted” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise.

Well-known functions or constructions may not be described in detail for brevity and/or clarity. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.