Remote electronic tilt base station antenna and mechanical calibration for such an antenna

Abstract

The RET regulator includes a drive assembly having a rotatable drive member operatively connected to a phase shifter assembly such that rotation of the drive member adjusts the phase shifter assembly. A first connector is coupled to the drive member, wherein the first connector occupies a rest position when the drive member is at rest. The drive system has a second connector that occupies a rest position when the drive system is at rest, wherein the second connector releasably engages the first connector such that actuation of the drive system rotates the drive member. A mechanical calibration system positions the second connector at the second rest position.

Description

Technical Field

[0001] The present invention relates to a communication system, and more particularly to a base station antenna with remote electronic tilt capabilities. Background Art

[0002] Cellular communication systems are used to provide wireless communication to fixed and mobile users. A cellular communication system may include a plurality of base stations, each of which provides wireless cellular service to a designated coverage area commonly referred to as a "cell". Each base station may include one or more base station antennas that are used to transmit radio frequency ("RF") signals to users within the cell served by the base station and to receive RF signals from those users. A base station antenna is a directional device that can concentrate the RF energy transmitted (or received from those directions) in certain directions. The "gain" of a base station antenna in a given direction is a measure of the antenna's ability to concentrate RF energy in that direction. The "radiation pattern" of a base station antenna (which is also referred to as an "antenna beam") is a compilation of the gains of the antenna in all different directions. Each antenna beam can be designed to serve a predetermined coverage area, such as a cell or a portion thereof, commonly referred to as a "sector". Each antenna beam can be designed to have a minimum gain level within its predetermined coverage area and a much lower gain level outside the coverage area to reduce interference between adjacent cells / sectors. A base station antenna typically includes a linear array of radiating elements, which are, for example, patch, dipole, or crossed dipole radiating elements. Many modern base station antennas now include multiple linear arrays of radiating elements, each of which generates its own antenna beam.

[0003] Early base station antennas generated antenna beams with a fixed shape, meaning that once the base station antenna was installed, its antenna beam could not be changed unless a technician physically reconfigured the antenna. Many modern base station antennas now have antenna beams that can be electronically reconfigured from a remote location. The most common way to electronically reconfigure an antenna beam is to change the pointing direction of the antenna beam (i.e., the direction in which the antenna beam has the highest gain), which is referred to as electronically "steering" the antenna beam. The antenna beam can be steered horizontally in the azimuth plane and / or vertically in the elevation plane. The antenna beam can be electronically steered by transmitting a control signal to the antenna, causing the antenna to change the phase of the sub-components of the RF signal transmitted and received by the individual radiating elements of the linear array that generates the antenna beam. Most modern base station antennas are constructed such that the elevation angle or "tilt" angle of the antenna beam generated by the antenna can be electronically changed. Such an antenna is commonly referred to as a remote electronic tilt ("RET") antenna.

[0004] To electronically change the downtilt angle of an antenna beam generated by a linear array of radiating elements, a phase taper can be applied to the radiating elements of the array. Such a phase taper can be applied by adjusting the settings on a phase shifter positioned along the RF transmission path between the radio device and the respective radiating elements of the linear array. A widely used type of phase shifter is the electromechanical “brush” phase shifter, which includes a main printed circuit board and a “brush” printed circuit board that can rotate above the main printed circuit board. Such a brush phase shifter typically divides an input RF signal received at the main printed circuit board into multiple subcomponents and then couples at least some of these subcomponents to the brush printed circuit board. The subcomponents of the RF signal can be coupled back to the main printed circuit board along multiple concentric arc-shaped traces, where each arc has a different diameter. Each end of each arc-shaped trace can be connected to a respective subgroup of radiating elements including at least one radiating element. By physically (mechanically) rotating the brush printed circuit board above the main printed circuit board, the position at which the subcomponents of the RF signal are coupled back to the main printed circuit board can be changed, thus changing the length of the transmission path from the phase shifter to the respective subgroup of radiating elements. These changes in path length result in a phase change of the respective subcomponents of the RF signal, and since the arcs have different radii, the phase changes along different paths will be different. Typically, a phase taper is applied by applying positive phase shifts of various magnitudes (e.g., +X°, +2X°, and +3X°) to some subcomponents of the RF signal and negative phase shifts of the same magnitude (e.g., -X°, -2X°, and -3X°) to other subcomponents of the RF signal. An exemplary phase shifter of this variant is discussed in U.S. Patent No. 7,907,096 to Timofeev, the disclosure of which is hereby incorporated by reference in its entirety. The brush printed circuit board is typically moved using an electromechanical actuator (e.g., a DC motor) connected to the brush printed circuit board via a mechanical linkage. These actuators are commonly referred to as “RET actuators”. Both individual RET actuators that drive a single mechanical linkage and “multi-RET actuators” having multiple output members that drive multiple or respective mechanical linkages are commonly used in base station antennas. SUMMARY OF THE INVENTION

[0005] According to an embodiment of the present invention, a RET adjuster includes a drive assembly. The drive assembly includes a rotatable drive member operatively connected to a phase shifter assembly such that rotation of the drive member adjusts the phase shifter assembly. A first connector is coupled to the drive member, and when the drive member is stationary, the first connector occupies a first stationary position. A drive system includes a second connector that occupies a second stationary position when the drive system is stationary. The second connector releasably engages the first connector such that actuation of the drive system selectively rotates the drive member. A mechanical calibration system positions the second connector at the second stationary position.

[0006] In some embodiments, the drive system may include a drive shaft connected to the second connector and a motor for rotating the drive shaft. The calibration system may include a stop member capable of rotating with the second connector. The calibration system may include a hard stop that can be engaged by the stop member. When the stop member engages the hard stop, the position of the second connector may be a known angular position relative to the second stationary position. The base station control system may include a processor and a memory for storing the known angular position. The drive member may include a lead screw and a drive nut, and wherein the drive nut is threadedly engaged with the lead screw, and the drive nut is operably connected to the phase shifter assembly. A plurality of drive assemblies operably connected to a plurality of phase shifter assemblies may be provided such that each drive assembly in the plurality of drive assemblies adjusts at least one phase shifter assembly in the plurality of phase shifter assemblies. The second connector may be capable of engaging the first connector by linear movement of the drive system relative to the drive member. The first connector may include a coupling member mounted on an end of the drive member for reciprocating movement relative to the drive member, and the coupling member rotates with the drive member. A spring may apply a force on the coupling member that tends to move the coupling member towards the second connector. The coupling member may include a plurality of first engagement structures arranged in a spaced-apart relationship about the rotational axis of the coupling member. The plurality of first engagement structures may be equally spaced about the rotational axis of the coupling member. The coupling member may include a locking member that engages a fixed locking member to fix the drive member in place. The spring may move the locking member into engagement with the fixed locking member. Engagement of the first connector with the second connector may disengage the locking member from the fixed locking member. The first connector may include a plurality of first engagement structures arranged about the rotational axis of the first connector. The plurality of first engagement structures may be equally spaced about the rotational axis of the first connector. The second connector may include a plurality of second engagement structures that matingly engage the plurality of first engagement structures on the first connector. The plurality of second engagement structures may be arranged about the rotational axis of the second connector. The plurality of second engagement structures may be equally spaced about the rotational axis of the second connector. The drive system may be supported for reciprocating movement transverse to the plurality of drive assemblies such that the drive system can be aligned with any one of the plurality of drive assemblies. The drive system may include a drive shaft connected to the second connector and a motor for rotating the drive shaft, wherein the drive shaft is supported in a bearing block. The drive shaft may have a first bevel gear at its end remote from the second connector, and the first bevel gear may engage a second bevel gear on the output shaft of the motor.The drive shaft may have a first section and a second section, and the first section may be arranged to move relative to the second section. The second bevel gear may be mounted for reciprocating movement on the output shaft such that the bevel gear may move reciprocally along the output shaft. A gear may rotate with the drive shaft, and the gear selectively engages a fixed rack such that actuation of the motor causes the drive shaft to move reciprocally laterally relative to the plurality of drive assemblies. A mode selection system may move the drive system between a drive mode, an indexing mode, and a calibration mode. The mode selection system may move the drive system such that a first connector engages a second connector. The mode selection system may move the gear to engage the rack. The mode selection system may move the drive system between a first position and a second position, in the first position, a stop member is positioned to engage a hard stop, and in the second position, the stop member is not positioned to engage the hard stop. When the drive system is in the second position, the first connector may engage the second connector. The plurality of drive assemblies may be operably connected to a plurality of phase shifter assemblies such that each drive assembly adjusts at least one of the plurality of phase shifter assemblies, and the mode selection system moves the drive system between a first position, a second position, and a third position. In the first position, the stop member may engage the hard stop, in the second position, the first connector may engage the second connector, and in the third position, the drive shaft may be supported for reciprocating movement laterally of the plurality of drive assemblies such that the drive system may be aligned with any one of the plurality of drive assemblies. The mode selection system may include a linear reciprocating slide that supports the drive system. Movement of the slide may cause the drive system to reciprocate between the first position, the second position, and the third position. The rack may be fixed to the slide and engaged by a pinion driven by a mode selection motor.

[0007] According to an embodiment of the present invention, a multi-RET regulator includes a plurality of rotatable drive members, wherein each of the plurality of rotatable drive members is operably connected to an associated phase shifter assembly such that rotation of the drive member adjusts the associated phase shifter assembly. A first connector is coupled to each of the plurality of drive members, and when the drive member is stationary, the first connector occupies a first stationary position. A drive system includes a second connector that occupies a second stationary position when the drive system is stationary, and the second connector releasably engages the first connector such that actuation of the drive system selectively moves the drive member. A mechanical calibration system positions the second connector at the second stationary position.

[0008] The drive system may include a rotatable drive shaft, wherein the second connector is mounted on the drive shaft. A stop member may be mounted to rotate with the drive shaft. A fixed stop may be positioned such that the stop member contacts the fixed stop when the drive system is in a first position. A plurality of fixed stops may be positioned such that when the drive system is in the first position, the stop member contacts one of the fixed stops. When the stop member contacts the fixed stop, the drive shaft may be in a second rest position. A mode selection system may move the drive system between a first position, a second position, and a third position. In the first position, the stop member may engage a hard stop, in the second position, the first connector may engage the second connector, and in the third position, the drive shaft may be supported for reciprocating movement transverse to the plurality of drive members such that the drive system may be aligned with any one of the plurality of drive members. The second rest position may be a known angular distance from the position of the drive system when the stop member contacts the fixed stop.

[0009] According to an embodiment of the present invention, a method of calibrating a RET adjuster, the RET adjuster including: a movable drive member operatively connected to a phase shifter assembly such that movement of the drive member adjusts the phase shifter assembly; a first connector coupled to the drive member, the first connector occupying a first rest position when the drive member is stationary; a drive system including a movable drive shaft and a stop member mounted to move with the drive shaft, the drive shaft supporting a second connector, the second connector occupying a second rest position when the drive system is stationary; the second connector being releasably engaged with the first connector such that actuation of the drive system moves the drive member. The method includes actuating the drive system to rotate the stop member into engagement with a fixed stop positioned such that the second connector is in a known position when the stop member contacts the fixed stop; and using the known position to position the second connector at the second rest position.

[0010] The known position may be the second rest position. The known position may be a known angular distance from the second rest position. Actuating the drive system may rotate the drive shaft and the stop member. The second rest position may be stored in a memory of a base station control system.

[0011] A method of operating a multi-RET adjuster, the multi-RET adjuster comprising: a plurality of rotatable drive members, wherein each of the plurality of rotatable drive members is operatively connected to an associated phase shifter assembly such that rotation of the drive member adjusts the associated phase shifter assembly; a first connector coupled to each of the plurality of drive members, the first connector occupying a first stationary position when the drive members are stationary; a drive system including a second connector that occupies a second stationary position when the drive system is stationary, the second connector releasably engaging the first connector such that actuation of the drive system moves the drive members. The method includes positioning the drive system adjacent to one of the plurality of rotatable drive members, the one of the plurality of rotatable drive members being operatively coupled to a phase shifter assembly to be adjusted; moving the drive system such that the second connector engages the first connector of the one of the plurality of rotatable drive members; and actuating the drive system to adjust the phase shifter assembly.

[0012] The step of positioning the drive system adjacent to one of the plurality of rotatable drive members may include: actuating a first motor to move the drive assembly to an indexing mode position; and actuating a second motor to index the drive system laterally relative to the plurality of rotatable drive members. A drive shaft may be connected to the second connector, and a gear may be mounted on the drive shaft to rotate with the drive shaft. When the drive system is in the indexing mode position, the gear may engage a rack. The step of moving the drive system may include actuating the first motor to move the drive assembly to a drive position. The step of actuating the drive system may include actuating the second motor to rotate the drive shaft connected to the second connector. The step of actuating the drive system may include rotating a lead screw to move a drive nut along the lead screw, wherein the drive nut is operatively connected to the phase shifter. BRIEF DESCRIPTION OF THE DRAWINGS [[ID=...]] [[ID=...]]

[0013] [[ID=...]] Figure 1A is a perspective view of an exemplary base station antenna according to an embodiment of the present invention.

[0014] Figure 1B is Figure 1A a perspective view of the base station antenna of, with its radome removed.

[0015] Figure 2 is a schematic block diagram showing Figures 1A - 1B the electrical connections between the various components of the base station antenna of.

[0016] Figure 3 is a front perspective view of a pair of electromechanical phase shifters that can be included in a Figures 1A - 1B base station antenna.

[0017] Figure 4 is a perspective view of an embodiment of a multi-RET actuator of the present invention that can be included in a Figures 1A - 1B base station antenna.

[0018] Figure 5 is a Figures 1A - 1B rear view of a portion of a RET base station antenna, showing how an output member of a Figure 4 multi-RET actuator is connected to corresponding phase shifters in Figure 2 and Figure 3 as shown in the phase shifters.

[0019] Figure 6 is a Figure 4 plan view of a multi-RET actuator, showing a driving mode.

[0020] Figure 7 is a cross-sectional view taken along line Figure 6 7-7.

[0021] Figure 8 is a Figure 4 plan view of a multi-RET actuator, showing a free mode.

[0022] Figure 9 is a Figure 4 plan view of a multi-RET actuator, showing a indexing mode.

[0023] Figure 10 is a Figure 4 plan view of a multi-RET actuator, showing a calibration mode.

[0024] Figure 11 is a Figure 10 detailed cross-sectional view taken along line 11-11.

[0025] Figure 12 is similar to Figure 7 a cross-sectional view, showing a driving mode.

[0026] Figure 13 is similar to Figure 7 a cross-sectional view, showing a free mode.

[0027] Figure 14 is similar to Figure 7 a cross-sectional view, showing a calibration mode.

[0028] Figure 15 is similar to Figure 7Cross-sectional view showing the indexing mode.

[0029] Figure 16 is a block diagram showing a method of operating the system of the present invention.

[0030] Figure 17 is a block diagram showing a method of operating the calibration system of the present invention. Detailed Description

[0031] Modern base station antennas typically include two, three or more linear arrays of radiating elements, each linear array having electronically adjustable downtilt. The linear arrays typically include cross-polarized radiating elements, and separate phase shifters are provided to electronically adjust the downtilt of the antenna beam for each polarization, such that the antenna can include, for example, twice as many phase shifters as the linear arrays. Moreover, in many antennas, separate transmit and receive phase shifters are provided such that the transmit and receive radiation patterns can be adjusted independently. This again doubles the number of phase shifters. Thus, it is not uncommon for a base station antenna to have eight, twelve, sixteen or more phase shifters to apply remote electronic downtilt to the linear arrays. As described above, RET actuators are provided in the antenna for adjusting the phase shifters. Although the same downtilt is typically applied to the phase shifters for two different polarizations, thereby allowing the use of a single RET actuator and a single mechanical linkage to adjust the phase shifters for both polarizations, modern base station antennas still often include four, six, eight or more RET actuators (or alternatively one or two multi-RET actuators) and associated mechanical linkages.

[0032] To change the downtilt angle of the antenna beam generated by the linear arrays on a base station antenna, a control signal can be transmitted from the base station control system to the antenna, the control signal causing the RET actuator associated with the linear array to produce a desired amount of movement in its output member. The movement can include, for example, linear movement or rotational movement. A mechanical linkage is used to convert the movement of the output member of the RET actuator into the movement of a movable element (e.g., a brush arm) of the phase shifter associated with the linear array. Thus, each mechanical linkage can extend between the output member of the RET actuator and the movable element of the phase shifter.

[0033] Since the adjustment of the phase shifter requires precise movement of the brush arm of the phase shifter, the precision of the RET actuator must be controlled to ensure that the downtilt angle of the antenna beam is correct. Repeated actuation of the RET actuator can result in inaccuracies being introduced into the system. Embodiments of the present invention provide a RET actuator and a mechanical calibration system for the RET actuator, the mechanical calibration system providing accurate adjustment of the phase shifter. Embodiments of the present invention also provide a low-profile, scalable and mechanically reliable RET actuator.

[0034] Embodiments of the present invention will now be discussed in more detail with reference to the accompanying drawings. In some instances, two-part reference numerals are used in the drawings. In this document, an element having such a two-part reference numeral may be referred to individually by its complete reference numeral (e.g., linear array 120-2), and may be referred to collectively by the first part of its reference numeral (e.g., linear array 120).

[0035] Figure 1A is a perspective view of a RET base station antenna 100 according to an embodiment of the present invention. Figure 1B is a perspective view of the base station antenna 100 with the radome removed to show four linear arrays of radiating elements included in the antenna 100.

[0036] As Figure 1A shown, the RET antenna 100 includes a radome 102, a mounting bracket 104, a bottom end cap 106, and a top end cap 120. A plurality of input / output ports 110 are mounted in the end cap 106. Coaxial cables (not shown) may be connected between the input / output ports 110 and RF ports on one or more radio devices (not shown). These coaxial cables may transmit RF signals between the radio devices and the base station antenna 100. The input / output ports 110 may also include a control port that transmits control signals to and from the base station antenna 100 from a base station antenna control system 250 ( Figure 5 ) that may be located remotely from the base station antenna 100. These control signals may include control signals for electronically changing the tilt angle of the antenna beam generated by the base station antenna 100.

[0037] For ease of reference, Figure 1A a coordinate system including axes (or directions) defining the length (L), width (T), and depth (V) of the base station antenna 100 will be discussed throughout the application. The length axis may also be referred to as the longitudinal axis.

[0038] Figure 1B is Figure 1A a perspective view of the base station antenna with the radome 102 removed. As Figure 1BAs shown, the base station antenna 100 includes two linear arrays 120-1, 120-2 of low-band radiation elements 122 (i.e., radiation elements that transmit and receive signals in a lower frequency band) and two linear arrays 130-1, 130-2 of high-band radiation elements 132 (i.e., radiation elements that transmit and receive signals in a higher frequency band). Each low-band radiation element 122 is implemented as a cross-polarized radiation element, which includes a first dipole oriented at an angle of -45° with respect to the azimuth plane (horizontal plane) and a second dipole oriented at an angle of +45° with respect to the azimuth plane. Similarly, each high-band radiation element 132 is implemented as a cross-polarized radiation element, which includes a first dipole oriented at an angle of -45° with respect to the azimuth plane and a second dipole oriented at an angle of +45° with respect to the azimuth plane. Since cross-polarized radiation elements are provided, each linear array 120-1, 120-2, 130-1, 130-2 will generate two antenna beams, i.e., a first antenna beam generated by the -45° dipole and a second antenna beam generated by the +45° dipole. The radiation elements 122, 132 extend forward from a backplane 112, which may include, for example, a metal sheet that serves as a ground plane for the radiation elements 122, 132.

[0039] Figure 2 is a schematic block diagram showing various additional components of the RET antenna 100 and their electrical connections. It should be noted that Figure 2 the actual positions of the various elements on the antenna 100 are not shown, but are drawn to show only the electrical transmission paths between the various elements.

[0040] As Figure 2 shown, each input / output port 110 can be connected to a phase shifter 150. The base station antenna 100 performs duplexing between the transmit and receive sub-bands for each linear array 120, 130 within the antenna (which allows different downtilts to be applied to the transmit and receive sub-bands), so each linear array 120, 130 includes a transmit (input) port 110 and a receive (output) port 110. The first end of each transmit port 110 can be connected to the transmit port of a radio device (not shown), such as a remote radio head. The other end of each transmit port 110 is coupled to a transmit phase shifter 150. Similarly, the first end of each receive port 110 can be connected to the receive port of a radio device (not shown), and the other end of each receive port 110 is coupled to a receive phase shifter 150. Two transmit ports, two receive ports, two transmit phase shifters, and two receive phase shifters are provided for each linear array 120, 130 to handle two different polarizations.

[0041] Each transmit phase shifter 150 divides an RF signal input thereto into five sub-components and applies a phase taper to these sub-components that sets the tilt angle (elevation angle) of an antenna beam generated by associated linear arrays 120, 130 of radiating elements 122, 132. The five outputs of each transmit phase shifter 150 are coupled to five respective diplexers 140 that transfer the sub-components of the RF signal output by the transmit phase shifter 150 to five respective sub-arrays of radiating elements 122, 132. In Figure 1A , 1B and the exemplary antenna 100 shown in FIG. 2, each low-band linear array 120 includes ten low-band radiating elements 122 that are grouped into five sub-arrays, each sub-array having two radiating elements 122. Each high-band linear array 130 includes fifteen high-band radiating elements 132 that are grouped into five sub-arrays, each sub-array having three radiating elements 132.

[0042] Each sub-array of radiating elements transfers a received RF signal to a respective one of the diplexers 140 that in turn route those received RF signals to respective inputs of an associated receive phase shifter 150. The receive phase shifter 150 applies a phase taper to each received RF signal input thereto to set the tilt angle of a receive antenna beam and then combines the received RF signals into a composite RF signal. The output of each receive phase shifter 150 is coupled to a respective receive port 110.

[0043] Although Figure 1B and Figure 2 show the antenna having two linear arrays 120 each having ten low-band radiating elements 122 and two linear arrays 130 each having fifteen high-band radiating elements 132, it should be appreciated that the number of linear arrays 120, 130 and the number of radiating elements 122, 132 included in each linear array 120, 130 can vary. It should also be appreciated that duplexing can be done in the radio device rather than in the antenna 100, the number of radiating elements 122, 132 in each sub-array can vary, different types of radiating elements (including single-polarization radiating elements) can be used, and many other changes can be made to the base station antenna 100 without departing from the scope of the present invention.

[0044] From Figure 2It can be seen that the base station antenna 100 can include a total of sixteen phase shifters 150. Although the two transmit phase shifters 150 of each linear array 120, 130 (i.e., one transmit phase shifter 150 for each polarization) may not need to be controlled independently (and the same is true for the two receive phase shifters 150 of each linear array 120, 130), there are still eight sets of two phase shifters 150 that should be independently controllable. Therefore, eight mechanical linkages may be required to connect the eight sets of phase shifters 150 to the corresponding RET actuators.

[0045] Figure 2 Each phase shifter 150 shown in may be implemented as a rotary brush phase shifter, for example. The phase shift imparted to each sub-component of the RF signal by the phase shifter 150 can be controlled by a mechanical positioning system that physically changes the position of the rotary brush of each phase shifter 150, as will be explained with reference to Figure 3 It will be appreciated that other types of phase shifters may be used instead of the rotary brush phase shifter, such as adjustable U-shaped phase shifters, sliding dielectric phase shifters, etc. For convenience, the movable elements for different types of phase shifters are collectively referred to as brush printed circuit boards herein.

[0046] Reference Figure 3 shows a dual rotary brush phase shifter assembly 200, which can be used to implement, for example, Figure 2 two of the phase shifters 150. The dual rotary brush phase shifter assembly 200 includes first and second phase shifters 202, 202a. In the following Figure 3 description, it is assumed that both phase shifters 202, 202a are transmit phase shifters having one input and five outputs. It should be appreciated that if the phase shifters 202, 202a are instead used as receive phase shifters, the terminology changes because when used as a receive phase shifter, there will be five inputs and a single output.

[0047] As Figure 3 shown, the dual phase shifter 200 includes first and second main (fixed) printed circuit boards 210, 210a arranged back-to-back and first and second rotatable brush printed circuit boards 220, 220a rotatably mounted on the respective main printed circuit boards 210, 210a (the brush printed circuit board 220a is hardly visible in the Figure 3 view). The brush printed circuit boards 220, 220a can be pivotally mounted on the respective main printed circuit boards 210, 210a via pivot pins 222. The brush printed circuit boards 220, 220a can be joined together at their distal ends via brackets 224.

[0048] The position of each rotatable brush printed circuit board 220, 220a above its respective main printed circuit board 210, 210a is determined by a drive shaft 228 (partially shown inFigure 3 Position control as shown in (), the end of the drive shaft can form one end of a mechanical linkage. The other end of the mechanical linkage (not shown) can be coupled to the output member of the RET actuator.

[0049] Each main printed circuit board 210, 210a includes transmission traces 212, 214. The transmission traces 212, 214 are generally arcuate. In some cases, the arcuate transmission traces 212, 214 can be arranged in a serpentine pattern to achieve a longer effective length. In Figure 3 the example shown, each main printed circuit board 210, 210a has two arcuate transmission traces 212, 214 (the traces on printed circuit board 210a are Figure 3 not visible), where the first arcuate transmission trace 212 is arranged along the outer circumference of each printed circuit board 210, 210a, and the second arcuate transmission trace 214 is concentrically arranged at a shorter radius within the outer transmission trace 212. The third transmission trace 216 on each main printed circuit board 210, 210a connects the input pads 230 on each main printed circuit board 210, 210a to the output pads 240 that do not undergo adjustable phase shift.

[0050] The main printed circuit board 210 includes one or more input traces 232 that lead from the input pads 230 near the edge of the main printed circuit board 210 to the location where the pivot pin 222 is located. The RF signal on the input traces 232 is typically coupled to the transmission traces on the brush printed circuit board 220 via a capacitive connection (not Figure 3 visible). The transmission traces on the brush printed circuit board 220 can be divided into two secondary transmission traces (not shown). The RF signal is capacitively coupled from the secondary transmission traces on the brush printed circuit board 220 to the transmission traces 212, 214 on the main printed circuit board. Each end of each transmission trace 212, 214 can be coupled to a corresponding output pad 240. A coaxial cable 260 or other RF transmission line component can be connected to the input pad 230. A corresponding coaxial cable 270 or other RF transmission line component can be connected to each corresponding output pad 240. When the brush printed circuit board 220 moves, the circuit path length from the input pad 230 of the phase shifter 202 to each output pad 240 changes. For example, when the brush printed circuit board 220 pivots to the left, as Figure 3As can be seen, it shortens the electrical length of the path from the input pad 230 to the output pad 240 that is connected to the left side of the transmission trace 212 (which is connected to the first sub-array of radiating elements), while increasing the electrical length of the path from the input pad 230 to the output pad 240 that is connected to the right side of the transmission trace 212 (which is connected to the second sub-array of radiating elements) by a corresponding amount. These changes in path length result in a phase shift of the signal received at the output pad 240 connected to the transmission trace 212 relative to, for example, the output pad 240 connected to the transmission trace 216.

[0051] The second phase shifter 202a can be the same as the first phase shifter 202. As Figure 3 shown, the rotating brush printed circuit board 220a of the phase shifter 202a can be controlled by the same drive shaft 228 as the rotating brush printed circuit board 220 of the phase shifter 202. Figure 5 is a rear view of a part of the base station antenna 100, showing how the output member of the RET actuator 300 is connected to the movable elements of the corresponding pairs of phase shifters 150 using the mechanical linkage 160. In Figure 5 only a few elements are given reference numerals to simplify the drawing (for example, only one of the mechanical linkages and two of the phase shifters are given reference numerals).

[0052] As Figure 5 shown, the multi-RET actuator 300 is mounted behind the backplane 112 in the antenna 100. Eight pairs of phase shifters 150 are also mounted behind the backplane 112 (only four pairs of phase shifters are visible in Figure 5 ). Since the base station antenna 100 has linear arrays 120, 130 formed by the dual-polarized radiating elements 122, 132, the phase shifters 150 are mounted in pairs because the phase shifters 150 for each polarization will be adjusted by the same amount. In Figure 5 the phase shifters 150-1 and 150-2 are used to adjust the phase tapers of the first-polarization radiator and the second-polarization radiator of the radiating elements 122 applied to the linear array 120-1. It should be noted that the phase shifters are Figure 5 positioned side by side in, as opposed to the front-to-back arrangement as Figure 3 shown.

[0053] As Figure 5 also shown, a plurality of mechanical linkages 160 are provided to connect each output member of the multi-RET actuator 300 to a corresponding pair of phase shifters 150. For example, the mechanical linkage 160-1 is connected between one of the outputs of the RET actuator 300 and the slider 154 of the phase shifter assembly that engages and rotationally moves the corresponding brush arms 152 of the phase shifters 150-1 and 150-2. As Figure 5As shown in FIG. 0, the mechanical linkage 160-1 includes a first RET rod 162 attached to the output of the multi-RET actuator 300, a second RET rod 166, a first RET linkage 164 connecting the first RET rod 162 to the second RET rod 166, and a slider 154 that engages the brush arms 152 of the phase shifters 150-1, 150-2. Figure 5 The other mechanical linkages 160 shown in FIG. include similar combinations of RET rods 162, 166 and RET linkages 164. The RET rods 162, 166 generally extend in the longitudinal direction of the antenna 100, while the RET linkage 164 generally extends along the width and / or depth axis to connect the RET rods 162, 166 together, and / or to connect the RET rods 162, 166 to the output member of the RET actuator or the movable element of the phase shifter assembly, e.g., the slider 154 that engages the brush arm 152. Each mechanical linkage 160 is used to transfer the linear movement of the output of the RET actuator 300 to the phase shifter assembly.

[0054] Reference Figures 4 to 15 , the RET actuator 300 is used to drive the movable element of the phase shifter 150, such as the brush printed circuit boards 220, 220a as described above. As shown in the figure, the housing 310 contains and supports the components of the multi-RET actuator, where multiple outputs are provided to drive multiple corresponding mechanical linkages 160. The housing 310 is shown as transparent in Figure 4 FIG., and in Figure 6 , 8 , 9 and 10, the housing 310 is opened to better illustrate the internal structure of the multi-RET actuator; however, in the actual construction, the housing 310 can be a closed opaque housing and can be made of a suitable rigid material, such as plastic, metal, or a combination of materials.

[0055] As is known in the art, the base station control system 250 ( Figure 5 ) controls the operation of the antenna 100. The base station control system 250 also controls the multi-RET actuator 300 as will be described below. The communication cable 302 can be used to deliver control signals from the base station control system 250 to the multi-RET actuator 300 and from the multi-RET actuator 300 to the base station control system 250.

[0056] In some embodiments, the base station control system 250 may include a processor 252 that is communicatively coupled to such devices as a memory 254 and a user interface 256. The processor 252 generally includes circuitry for implementing the communication and / or logic functions of the antenna. The processor 252 may include functionality for operating one or more software programs that may be stored in the memory 254. The base station control system 250 may be located remotely from the antenna 100, may be co-located with the antenna 100, or various functions of the base station control system 250 may be distributed between the antenna and a remote location.

[0057] As used herein, a "processor" refers to a device or combination of devices having circuitry for implementing the communication and / or logic functions of a system. For example, a processor may include digital signal processor devices, microprocessor devices, and various analog-to-digital converters, digital-to-analog converters, and other support circuitry and / or combinations of the foregoing. The control and signal processing functions of the system are distributed among these processing devices according to their respective capabilities. A processor may also include functionality for operating one or more software programs based on its computer-executable program code that may be stored in the memory 254. As used in the phrases herein, a processor may be "configured to" perform a certain function in a variety of ways, the variety of ways including, for example, causing one or more general-purpose circuits to perform the function by executing specific computer-executable program code contained in a computer-readable medium, and / or causing one or more dedicated circuits to perform the function.

[0058] As used herein, "memory" generally refers to one or more forms of a device or combination of devices that store computer-readable media for storing data and / or computer-executable program code / instructions. For example, in one embodiment, the memory 254 as described herein includes any computer memory that provides physical or virtual space to temporarily or permanently store data and / or commands provided to the processor 252 when the processor performs its functions as described herein. As used herein, "memory" includes any computer-readable medium configured to store data, code, or other information. Memory may include volatile memory (such as volatile random access memory (RAM)), which includes a cache area for temporarily storing data. Memory may also include non-volatile memory, which may be embedded and / or removable. Non-volatile memory may additionally or alternatively include electrically erasable programmable read-only memory (EEPROM), flash memory, and the like.

[0059] The user interface 256 may be constituted by a user output device and / or a user input device operatively coupled to the processor 210. The user output device may include a visual display, an audio device, etc. The user input device may include any of a number of devices that allow the base station control system 250 to receive data, such as a keypad, a keyboard, a touch screen, a touch pad, a microphone, a mouse, a joystick, other pointer devices, buttons, soft keys, and / or other input devices.

[0060] Referring again to Figures 4 to 15 , a multi-RET actuator 300 having four drive assemblies 306a-306d is shown. The four drive assemblies 306a–306d may move four or more mechanical linkages, where each drive assembly 306a–306d is operatively connected by a mechanical linkage to at least one phase shifter assembly. Although four drive assemblies 306a-306d are shown, the multi-RET actuator 300 is scalable such that the multi-RET actuator 300 may include a greater or lesser number of drive assemblies 306 to drive a greater or lesser number of mechanical linkages. Each of the drive assemblies 306a–306d includes a drive mechanism for converting a rotational input into a linear output. In one embodiment, the drive assemblies 306a–306d include a rotary drive member operatively connected to the linear output. The linear output is operatively coupled by a mechanical linkage to the brush printed circuit boards 220, 220a of the phase shifter assembly 200 such that movement of the linear output adjusts the phase shifter assembly. The drive assemblies 306a-306d are identical such that a single drive assembly 306a will be described in detail. In one embodiment, the drive member includes a lead screw 312 rotatably supported in a housing 310 such that the lead screw 312 may be rotated along its longitudinal axis. The drive member may also include a belt drive, a chain drive, a ball drive, a gear drive, a linkage, etc., or a combination of such devices.

[0061] The distal end of the lead screw 312 may be supported in a suitable bearing 313 in a first wall 315 of the housing 310. The proximal end of the lead screw 312 includes a screw connector 314 that is mounted to the lead screw 312 for rotation therewith. The screw connector 314 includes a coupling member 324 that includes a lug 316 that is rotatably supported in an aperture 318 in a wall 319 of the housing 310 and extends through the aperture. The lead screws 312 of the drive assemblies 306a–306d are arranged parallel to each other.

[0062] Provides a linear output for transferring rotation of a drive member to a mechanical linkage. In one embodiment, the linear output includes a drive nut 320 that threadably engages a lead screw 312 such that rotation of the lead screw 312 causes the drive nut 320 to reciprocate along the length of the lead screw 312. The drive nut 320 includes a tab structure 321 for connecting the drive nut to the mechanical linkage. The tab structure 321 can include any suitable connecting mechanism. A fixed rod 322 is supported in the housing 310 and extends parallel to the lead screw 312. The rod 322 can extend through a bearing sleeve 323 in the drive nut 320 to prevent rotation of the drive nut 320 and guide the drive nut 320 along the length of the lead screw 312 in a linear travel path. The direction of rotation of the lead screw 312 can be reversed to change the direction of travel of the drive nut 320 along the lead screw. The mechanical linkage of the brush printed circuit boards 220, 220a connected to the phase shifter assembly 200 is connected to the drive nut 320 such that reciprocation of the drive nut 320 causes the phase shifter assembly to be adjusted as described above.

[0063] A screw connector 314 releasably connects the lead screw 312 to a drive connector 400 of a drive system 401. The screw connector 314 is configured such that the drive connector 400 can be selectively connected to and released from the screw connector 314 by linear movement of the drive connector 400 along the rotational axis of the lead screw 312 relative to the screw connector 314. As will be described, the screw connector 314 is also used to lock the drive assemblies 306a–306d in place during use of a multi-RET actuator.

[0064] A coupling member 324 of the screw connector 314 is mounted on the end of the lead screw 312 for reciprocating movement relative to it along the longitudinal axis of the lead screw 312. In the illustrated embodiment, the coupling member 324 has a cup-shaped configuration in which an internal recess 326 mates over the end of the lead screw 312 such that the coupling member 324 can reciprocate relative to the lead screw 312 but is prevented from rotating relative to the lead screw. In the illustrated embodiment, the proximal end of the lead screw 312 and the recess 326 of the coupling member 324 are provided with a series of flat surfaces, such as a hexagonal connector, which allows reciprocating movement between the coupling member 324 and the lead screw 312 but prevents relative rotational movement therebetween. Although mating flat surfaces are used in the illustrated embodiment to connect the coupling member 324 to the end of the lead screw 312, other mechanisms, such as key connections, pin and slot arrangements, etc., can be used. A spring 328 exerts a force on the coupling member 324 that tends to move the coupling member 324 away from the lead screw 312 towards the drive connector 400. The spring 328 can include a compression spring that is located in a longitudinally extending recess 330 formed in the end of the lead screw 312.

[0065] The projection 316 of the coupling member 324 faces the drive connector 400. The projection 332 includes a series of engagement structures 334 arranged in a spaced-apart relationship about the axis of rotation of the projection 316. The engagement structures 334 may include a series of external teeth, flat surfaces, splines, star sockets, etc., which cooperate with and releasably engage corresponding engagement structures formed on the drive connector 400 to transmit the rotational movement of the drive connector 400 to the lead screw 312. Although specific engagement structures including multiple teeth are shown and described herein, any suitable engagement structure that provides a releasable rotary connection to the drive connector 400 may be used, as long as the engagement structure allows the lead screw 312 to be angularly positioned relative to the drive system 401, as will be described below. In this regard, the engagement structures 334 include a plurality of discrete elements arranged at known angular positions about the axis of rotation of the lead screw. For example, a series of equally spaced teeth as shown in the figure may be used.

[0066] The coupling member 324 further includes an outwardly projecting flange or lip 344. The flange 344 includes a series of spaced-apart locking members 346( Figure 6 ), which are arranged in an annular configuration about the longitudinal axis of the coupling member 324 facing the wall 319. The wall 319 includes a series of fixed locking members 350 that extend from the wall 319 and face the locking members 346 on the flange 344. The locking members 350 and the locking members 346 engage each other to fix the lead screw 312 in place when the lead screw is not adjusted and is in a stationary position. The locking members 346, 350 may be formed as a series of projecting teeth, and in one embodiment, as a series of generally triangular teeth that allow the locking members to engage each other even if slightly misaligned. Although the locking members 346, 350 may be formed as a series of teeth, the locking members may be configured as other than teeth, such as rough friction surfaces, ridges, pins, and apertures, etc., as long as the mutual engagement of the locking members 346, 350 locks the lead screw 312 in place.

[0067] In the absence of a reaction force, the spring 328 causes the coupling member 324 to extend away from the lead screw 312 such that the locking members 346 on the flange 344 engage the locking members 350 on the wall 319. The engagement of the locking member 346 with the locking member 350 prevents the coupling member 324 from rotating. The key engagement of the coupling member 324 with the lead screw 312 prevents the lead screw 312 from rotating relative to the coupling member 324. Thus, the engagement of the locking member 346 and the locking member 350 prevents the lead screw 312 from rotating, thereby locking the drive nut 320 in place and fixing the position of the mechanical linkage of the phase shifter assembly 220 and the corresponding brush printed circuit boards 220, 220a.

[0068] The drive / indexing mechanism will now be described. The drive / indexing mechanism includes a drive system 401 and an indexing system 422. The drive system rotates the lead screw 312 to adjust the position of the associated phase shifter assembly 220, and the indexing system changes the position of the drive system relative to the lead screw 312 of the drive assemblies 306a–306d. The drive system 401 includes a drive shaft 406 that rotates about its longitudinal axis. A drive connector 400 is supported at one end of the drive shaft 406 such that the drive connector 400 rotates with the drive shaft 406. The screw connector 314 and the drive connector 400 are configured such that when they are engaged with each other in the drive mode, as Figure 6 , 7 and as shown in 12, the rotation of the drive shaft 406 is transmitted to the lead screw 312.

[0069] The drive connector 400 includes a generally socket-shaped member 402 that receives the lug 316 of the screw connector 314. The socket 402 includes a plurality of engagement structures 408 that mate with corresponding engagement structures 334 formed on the screw connector 314 and transmit the rotational movement of the drive shaft 406 to the drive screw 312. The engagement structures 408 can be formed as a series of internal flats, splines, teeth, star connectors, etc. Although the figure shows a specific connector including a series of angled spaced teeth, any suitable connector that provides a releasable rotary connector and allows the use of relative linear movement between the connectors 314, 400 to connect the connectors can be used, provided that the engagement structure allows the drive connector 400 to be angularly positioned relative to the screw connector 314, as will be described below. In this regard, an engagement structure can be used that includes a plurality of discrete elements arranged at known angular positions about the rotational axis of the drive shaft 406. For example, a series of equally spaced teeth as shown in the figure can be used.

[0070] The drive shaft 406 includes telescoping sections 406a, 406b that slide relative to each other along the longitudinal axis of the drive shaft 406 ( Figures 12 - 15)。Although sections 406a, 406b can telescope relative to each other, they are constrained to rotate together. For example, the inner bore of section 406a has a flat surface that engages a flat surface on the exterior of section 406b such that section 406b can slide into and out of section 406a along the length of the section, but sections 406a, 406b are constrained to rotate together. Section 406a is rotatably supported in bearing block 409, and section 406b has a bevel gear 410 formed at its end that extends away from connector 400. Bevel gear 410 engages a bevel gear 412 mounted on output shaft 414 of drive / indexing motor 416. The ends of output shaft 414 and drive shaft 406 can be supported in a common bearing block 419. Energization of drive / indexing motor 416 causes output shaft 414 to rotate, thereby causing drive shaft 406 and drive connector 400 to rotate.

[0071] Bearing block 409 is supported on a carriage system that includes a rod 418 and parallel tracks 420 that permit bearing block 409 to reciprocate laterally relative to lead screw 312 of drive assembly 306a - 306d such that drive shaft 406 can be aligned with any lead screw 312. Bevel gear 412 is mounted for reciprocating movement along the length of output shaft 414 such that bevel gear 412 can reciprocate along the length of output shaft 414 with drive shaft 406 and bearing block 419. Specifically, output shaft 414 has a flat surface 414a that engages a flat surface on bevel gear 412 such that bevel gear 412 can slide along the length of output shaft 414 but is constrained to rotate with output shaft 414. As a result, when bearing blocks 409, 419 reciprocate laterally relative to lead screw 312 of drive assembly 306a - 306d, bevel gear 412 slides along output shaft 414.

[0072] Drive system 401 can be indexed by an indexing system 422 that uses the same drive / indexing motor 416 that rotates drive shaft 406. Indexing system 422 includes a circular gear 430 coaxially disposed with and fixed to drive shaft 406 such that rotation of drive shaft 406 causes simultaneous rotation of gear 430. Rack 432 is fixed in housing 302 such that when the device is in a position as Figure 4 , 9When in the indexing mode shown in FIGS. 14 and 15, the rack is engaged by the mating of gear 430. In the indexing mode, the mode selection system 500 positions gear 430 such that it engages rack 432, as will be described below. With gear 430 engaged with rack 432, actuation of drive / indexing motor 416 causes drive shaft 406 to rotate, thereby causing gear 430 to rotate. Since gear 430 is engaged with rack 432, drive shaft 406, bearing blocks 409 and 419, and bevel gear 412 translate laterally relative to lead screw 312 of drive assembly 306a–306d to index the drive system and align drive shaft 406 with a selected one of lead screws 312. In the indexing mode, drive connector 400 disengages from screw connector 314 such that rotation of the drive shaft does not cause either of lead screws 312 to rotate.

[0073] Information regarding the position of drive shaft 406 relative to drive assembly 306a–306d is stored in memory 254 of base station control system 250. Base station control system 250 actuates drive / indexing motor 416 on communication link 302 to rotate drive shaft 406 a predetermined angular rotation distance (number of rotations) and direction to position drive system 401 relative to a selected one of drive assemblies 306a–306d. In some embodiments, base station control system 250 stores the current position of drive system 401 in memory 254. Base station control system 250 also stores the direction and angular rotation distance of motor 416 to move drive shaft 406 from the current position to each of three positions aligned with the other drive assemblies 306a–306d. When a phase shifter to be adjusted is selected at base station control system 250, e.g., via user interface 256, base station control system 250 controls motor 416 to rotate shaft 406 a predetermined number of rotations in the appropriate direction to move from the stored current position to the selected position. The new selected position is then stored as the current position in memory 254. The indexing process can be repeated to move drive system 401 to align with any of drive assemblies 306a–306d.

[0074] The mode selection system 500 will now be described. The mode selection system 500 moves drive system 401 between one of four positions or modes - drive mode, indexing mode, calibration mode, and free mode. In the drive mode, drive system 401 moves fully towards lead screw 312 of drive assembly 306a–306d such that screw connector 314 is engaged by drive connector 400, as Figure 6 , 7as shown in FIGS. 12. In the drive mode position, rotation of the drive shaft 406 causes the lead screw 312 to rotate to adjust the position of the brush printed circuit boards 220, 220a of the phase shifter assembly 200 operatively coupled to the lead screw 312. In the indexing mode, the drive system 401 moves to the indexing mode position where the gear 430 engages the rack 432, as Figure 4 , 9 shown in FIGS. 15. In this position, rotation of the drive shaft 406 causes the drive system 401 to index laterally relative to the lead screw 312 to align the drive shaft 406 with one of the lead screws 312 of the drive assemblies 306a - 306d. In the calibration mode, the drive system 401 moves to the calibration position where the gear 430 disengages from the rack 432 and the drive connector 400 disengages from the screw connector 314, as Figure 10 , 11 shown in FIGS. 14. In the calibration mode position, rotation of the drive shaft 406 is used to calibrate the system, as will be described below. The system can also be indexed to a fourth free mode position. In the free mode, the drive system 401 moves to a position where the gear 430 disengages from the rack 432, the drive connector 400 disengages from the screw connector 314, and the device is not in the calibration mode, as Figure 8 and Figure 13 shown in FIGS. In the free mode, the drive shaft 406 can rotate freely without affecting the operation of the system.

[0075] The mode selection system 500 includes a linear reciprocating slide 502 that supports a drive shaft 406 and bearing blocks 409, as well as carriers 418, 420. Movement of the slide 502 causes the drive system 401 to reciprocate between the indexing mode, drive mode, calibration mode, and free mode described above. The slide 502 includes a generally flat platform 506 that supports the drive shaft 406 and bearing blocks 409, as well as carriers 418, 420. The slide 502 includes a bearing block 508 that is connected to the platform 506 and is slidably supported on a rod 510. The rod 510 extends parallel to the lead screw 312 such that when the bearing block 508 slides on the rod 510, the slide 502 and the drive system 401 can linearly reciprocate between the indexing mode, drive mode, calibration mode, and free mode. To effect movement of the slide 502, a rack 512 is fixed to the platform 506 and extends parallel to the rod 510 in the direction of travel of the slide 502. A pinion 514 is supported on the output shaft 518 of a mode selection motor 520 and rotates with the output shaft. The mode selection motor 520 and the output shaft 518 are fixed in a housing 302 such that rotation of the output shaft 518 causes the pinion 514 to rotate and causes the slide 502 to linearly reciprocate toward and away from the lead screw 312 of the drive assemblies 306a–306d. When the slide 502 reciprocates, the bearing block 409 moves with the slide, and the shaft sections 406a, 406b move telescopically relative to each other to accommodate movement of the slide 502 and the bearing block 409 relative to the bearing block 419.

[0076] Information regarding the relative position of the slide 502 is stored in the memory 254 of the base station control system 250 for each of the four positions or modes: drive mode, indexing mode, calibration mode, and free mode. The base station control system 250 actuates the mode selection motor 520 to rotate the output shaft 518 a predetermined angular distance to position the drive system 401 in a selected one of the four modes. In some embodiments, the base station control system 250 stores the position of the motor 520 associated with the four mode positions and rotates the motor 520 to the correct position based on the selected mode. The motor 520 can provide feedback to the base station control system indicating the motor position on the linkage 302. In other embodiments, the base station control system 250 stores in memory the current position of the mode system, as well as the direction and angular rotation of the shaft 518, to move the slide 502 to each of the four mode positions such that when a mode is selected, the base station control system 250 rotates the output shaft 518 in the appropriate direction a predetermined number of rotations to move from the stored current position to the selected position. The newly selected position is then stored as the current position.

[0077] The operation of the multi-RET actuator 300 for adjusting the phase shifter will be described. It should be understood that the system operates in a repetitive manner such that any position of the system can be considered a starting point and the system can move between four operating modes based on control signals from the base station control system 250. To adjust the position of the brush printed circuit boards 220, 220a of a selected phase shifter assembly in the phase shifter assembly 200, the desired adjustment is received as an input (block 1601) by the user interface 256 of the base station control system 200. The input can include the identification of the selected phase shifter assembly and the adjustment level. The adjustment level can be input as the direction and change angle of the brush printed circuit boards 220, 220a, or it can be input as a phase taper or using other data. The base station control system 250 uses the adjustment level to identify the brush printed circuit board / drive assembly 306a–306b to be adjusted and the amount and direction of rotation of the lead screw 312 corresponding to the adjustment level. The base station control system 250 controls the indexing system 422 and the mode selection system 500 to position the drive system 401 near the lead screw 312 of the drive assemblies 306a–306d, which is operably coupled to the phase shifter assembly to be adjusted. The base station control system 250 determines whether the drive system 401 is positioned at the selected drive assembly 306a–306d (block 1602). If the drive system 401 is located at the selected drive assembly 306a–306d, no indexing of the drive system is required. If the drive system 401 is not positioned at the selected drive assembly 306a–306d, the base station control system 250 actuates the mode selection motor 520 to move the slide plate 502 to the indexing mode position, where the circular gear 430 engages the rack 432, as shown in Figure 4 , 9 and 15 (block 1603). If the system is in the indexing mode position, the mode selection motor is not actuated. Then, the indexing / drive motor 416 is actuated to rotate the drive shaft 406 and the circular gear 430 to move the drive system to the selected drive assembly 306a–306d (block 1604). The engagement of the rotating circular gear 430 with the fixed rack 432 indexes the drive system 401 laterally with respect to the lead screw 312 of the drive assemblies 306a-306d. The indexing / drive motor 416 is energized until the drive shaft 406 and the drive connector 400 are aligned with the lead screw 312, which is operably coupled to the selected phase shifter assembly 200. The indexing / drive motor 416 is deactivated.

[0078] The mode selection system 500 is then used to move the RET actuator to the drive mode, where the drive connector 400 engages the lead screw connector 314 (block 1605). Specifically, the base station control system 250 actuates the mode selection motor 520 to move the slide plate 502 towards the selected drive assembly such that the drive connector 400 engages the lead screw connector 314 of the lead screw 312 of the selected drive assembly 306a–306d, as shown in Figure 6 , 7 and 12. The engagement structure 408 on the drive connector 400 engages the engagement structure 334 on the lead screw connector 314. When the drive connector 400 is moved into engagement with the lead screw connector 314, a force is applied to the coupling member 324 that overcomes the bias of the spring 328 to move the coupling member 324, such that the teeth 346 on the lead screw connector 314 disengage from the teeth 350 on the wall 319, as shown in Figure 6 for drive assembly 306a. In this position, the lead screw connector 314 and the lead screw 312 are free to rotate.

[0079] The base station control system 250 actuates the drive system 401 to move the brush printed circuit board of the phase shifter assembly to the desired position (block 1606). The drive / indexing motor 416 is energized to rotate the drive shaft 406 and the coupled lead screw 312. When the lead screw 312 rotates, the drive nut 320 linearly moves along the length of the lead screw. The linear movement of the drive nut 320 is transmitted to the mechanical linkage connected to the brush printed circuit boards 220, 220a of the selected phase shifter assembly such that the movement of the drive nut 320 causes the rotation and / or linear adjustment of the brush printed circuit board. The adjustment of the brush printed circuit board can be made at the adjustment angle for pivoting the brush printed circuit board or at the linear distance for the linearly movable brush printed circuit board. In either case, the movement of the brush printed circuit board is related to the number of rotations of the lead screw 312. Thus, the base station control system 250 controls the rotation of the drive shaft 406 to rotate the lead screw 312 in the appropriate direction and number of rotations for the selected adjustment. The base station control system 250 stores the current position of each of the brush printed circuit boards in the memory 254. When it is necessary to adjust the position of one of the brush printed circuit boards, the control system 250 (by calculation, look-up table, etc.) determines the number and direction of rotation of the lead screw 312 and the drive shaft 406 corresponding to the selected position. The indexing / drive motor 416 is actuated to rotate the drive shaft 406 and the lead screw 312 in the desired direction of rotation by the determined number of rotations to move the brush printed circuit board to the selected position. The selected position is then stored in the memory 254 as the current position.

[0080] It should be understood that there is a relationship between the number of rotations of the lead screw 312 and the linear distance traversed by the drive nut 320 along the lead screw 312 and the corresponding distance moved by the mechanical linkage. The distance moved by the mechanical linkage corresponds to a known movement of the brush printed circuit board. Thus, the rotational movement of the lead screw 312 is related to the known movement of the associated brush printed circuit board. Therefore, in order to adjust the position of the brush printed circuit board of the phase shifter assembly, the lead screw 312 operatively coupled to the brush printed circuit board is rotated by the drive motor 416 by a corresponding number of rotations in the correct direction. In a system where the brush printed circuit board of the phase shifter assembly moves linearly rather than rotationally, the rotational movement of the lead screw 312 is related to the linear movement of the brush printed circuit board. In all cases, the rotational movement of the lead screw 312 corresponds to a known movement of the brush printed circuit board of the phase shifter assembly such that the movement and position of the brush printed circuit board can be controlled by the known rotational movement of the lead screw 312. To position the brush printed circuit board, the lead screw 312 is rotated by the indexing / drive motor 416 by a known number of rotations or degrees of rotation in the correct direction. When the desired position of the lead screw 312 is reached, the indexing / drive motor 416 is turned off.

[0081] Then, the drive system 401 can be retracted to the indexing mode position, the free mode position, or the calibration mode position (block 1607). The drive system 401 is retracted by energizing the mode selection motor 520 to drive the gear 514 into engagement with the rack 512. When the drive system 401 is retracted, the force applied by the drive system to the spring 328 is removed such that the spring 328 moves the coupling member 324 to the extended position where the teeth 346 on the coupling member 324 engage the fixed teeth 350 on the wall 319 to hold the lead screw 312 in the selected position. The process can be repeated for any phase shifter assembly that needs adjustment and can be repeated for each phase shifter assembly.

[0082] In one embodiment, each screw connector 314 is provided with eight engagement structures 334 spaced 45 degrees apart. Each drive connector 400 is also provided with eight mating engagement structures 408 spaced 45 degrees apart. The lead screw 312 is always stationary positioned in one of eight positions with the eight engagement structures 334 in the same relative angular position. The rotatable lead screw 312 can be rotated a minimum of 45 degrees, i.e., an angular distance between two adjacent engagement structures 334, and can be rotated by an angle that is a multiple of �5 degrees. In one embodiment, a 45-degree angular rotation of the lead screw 312 can be converted into a.2 mm adjustment of the brush printed circuit board based on the geometry of the system. However, the relationship between the angular rotation of the lead screw 312 and the adjustment of the brush plate can vary. Additionally, a greater or lesser number of engagement structures can be used to thereby increase or decrease the minimum angular adjustment of the lead screw 312.

[0083] The drive system 401 can rotate the lead screw 312 by multiples of 45 degrees of rotation based on the desired adjustment of the brush printed circuit board. As a result, the screw connector 314 is always positioned in a stationary position, and the engagement structure 334 is positioned in the same relative angular position. The screw connector 314 and the associated lead screw 312 are held in the stationary position by the engagement of the locking member 346 and the fixed locking member 350. It should be understood that in the stationary position, the screw connector 314 is always positioned such that the engagement member 334 occupies the same relative angular position; however, the position of the brush printed circuit board will vary based on the rotation of the associated lead screw. Thus, if the lead screw 312 is rotated 360 degrees, the engagement member 334 is in the same angular position, but the drive nut 320 will have moved up or down along the length of the lead screw 312, and the position of the brush printed circuit board will have been adjusted. Similarly, if the lead screw 312 is rotated 540 degrees, the engagement member 334 is in the same relative angular position, but rotated 180 degrees in the absolute position, and the drive nut 320 will be moved up or down along the length of the lead screw 312 by a corresponding distance, and the position of the brush printed circuit board will be adjusted accordingly.

[0084] The drive connector 400 must be aligned with the screw connector 314 to allow the engagement member 408 of the drive connector 400 to engage the engagement member 334 of the screw connector 314 without interference. Thus, the drive connector 400 must be stationary and in the same stationary position as the screw connector 314. It should be understood that the stationary position of the drive connector can be any one of a plurality of angular positions of the drive connector, where the drive connector is aligned with the screw connector, and any one of the angular positions can be the stationary position. When the drive connector is in the stationary position, the engagement structure on the drive connector is aligned with the engagement structure on the screw connector. As previously explained with respect to the screw connector, the stationary position of the drive connector can correspond to any one of a plurality of angular positions of the drive connector. For example, each drive connector 400 can be provided with eight mating engagement structures 408 spaced 45 degrees apart, where the drive connector 400 can be in any one of eight positions when in the stationary position, with the eight engagement structures 408 in the same relative angular position. If the drive connector 400 is offset from the stationary position, when the drive connector 400 is moved to engage the screw connector 314, the engagement member 408 of the drive connector 400 will interfere with the engagement member 334 of the screw connector 314 when the connection between the connectors is established. If such interference occurs between the engagement member 408 of the drive connector 400 and the engagement member 334 of the screw connector 314, the drive connector 400 can cause the screw connector 314 and the associated lead screw 312 to rotate inadvertently. Repeated engagement and disengagement of the screw connector 314 with a misaligned drive connector 400 can introduce errors over time in the position of the brush printed circuit board of the phase shifter assembly. These positioning errors can also be complicated because the next adjustment of the out-of-place brush printed circuit board is based on an inaccurate starting position. The system operator may not detect these errors in the positioning and repositioning of the brush printed circuit board until performance issues occur.

[0085] Due to the inherent inaccuracies in the transmission assembly of the drive motor 416 and the drive connector 400, the drive shaft 406 and the drive connector 400 can stop at positions other than the stationary position during repeated actuation. The system of the present invention provides a calibration mode to ensure proper alignment of the drive system 401 and the drive connector in the stationary position. The calibration process can be performed during system setup to ensure proper positioning of the drive connector 400. The calibration process can also be performed periodically during system use to ensure that the drive system and the drive connector remain properly aligned. For example, the calibration process can be performed in accordance with the instructions of the system operator or after a predetermined number of cycles, such as 1000 cycles, to maintain proper alignment of the system in the field.

[0086] To calibrate the system, the system operates in a calibration mode. To initiate calibration of the system, a calibration command can be received by the user interface 256 of the base station control system 200. Alternatively, the base station control system 250 can automatically calibrate the system based on an operating cycle, time, or other factors stored in the memory 254. In either case, the base station control system 200 initiates the calibration process (block 1701). The base station control system 250 determines whether the drive system is positioned at the calibration mode position (block 1702). If the drive system is at the calibration mode position, the mode selection system is not used. If the drive system is not positioned at the calibration mode position, the base station control system 250 actuates the mode selection motor 520 to move the slide plate 502 to the calibration position (block 1703). In the illustrated embodiment, the calibration position is between the drive position and the indexing position. The calibration position is shown in Figure 10 , 11 and 14, where the drive connector 400 is not engaged with the lead screw connector 314 and the circular gear 430 is not engaged with the rack 432. Although in the illustrated embodiment the calibration position is a physical mid-position between the drive position and the indexing position, in some embodiments the calibration position can be, for example, behind the indexing position as long as the drive connector 400 is not engaged with the lead screw connector 314 and the circular gear 430 is not engaged with the rack 432. At the calibration position, actuation of the drive motor 416 rotates the drive shaft 406, but does not index the drive system and does not rotate any of the lead screws 312.

[0087] With more specific reference to Figure 11 , the positioning member 600 is mounted to rotate with the drive shaft 406. In the illustrated embodiment, the positioning member 600 is in the form of a ring 602 mounted on the shaft 406 for rotation with the shaft. A stop member 604 in the form of a tab or ear extends from the ring 602. When the drive shaft 406 rotates and the drive system is in the calibration mode, the stop member 604 is positioned to strike a hard stop 608. In the illustrated embodiment, the hard stop 608 includes a protrusion extending upward from the housing 310. In the illustrated embodiment, one hard stop 608 is associated with each lateral position of the drive system 401 such that calibration can be performed with the drive system aligned with any of the lead screws 312. In other embodiments, a single hard stop 608 can be provided, where the calibration process can only be performed after the drive system has been indexed to that position.

[0088] The base station control system 250 energizes the indexing / drive motor 416 until the stop member 604 contacts the hard stop 608 (block 1704). This position is a known angular position of the drive connector 400. This known position can be the rest position of the drive connector 400, or it can be a position that is a known or predetermined angular distance from the rest position of the drive connector 400. If the known position is the rest position of the drive connector 400, the drive connector is properly positioned and located at the rest position. If the known position is a known angular distance from the rest position, the drive shaft 406 is rotated a known or predetermined angular distance by the drive / indexing motor 416 to position the drive shaft 406 and the drive connector 400 at the rest position (block 1705). The software registers the calibrated position as the rest position and calculates future rotations of the drive shaft from this position to adjust the lead screw 312 (block 1706). The next adjustment of the brush printed circuit board is made from the correct rest position, thereby eliminating errors caused by misalignment of the drive system.

[0089] The system of the present invention is scalable such that more or fewer drive assemblies 306 can be provided. In some embodiments, the RET regulator can be a single RET regulator with a single drive assembly, where the indexing system can be dispensed with. The calibration system as described herein can be used with a single RET system having a single drive assembly. The RET regulator of the present invention also has a narrow profile such that it can better fit within the limited space of the antenna. The low profile is provided because the drive system elements are located in a common plane. As shown in the figure, the motors 416, 520, the shafts 406, 414, and 518, and the drive assembly 306 are all in a common plane such that the RET regulator has a very small depth dimension.

[0090] The present invention has been described above with reference to the accompanying drawings. The present invention is not limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the present invention to those skilled in the art. In the drawings, the same reference numerals always denote the same elements. The thickness and dimensions of some elements may be out of proportion.

[0091] For ease of description, spatial relative terms, such as "below", "beneath", "lower", "above", "upper", "top", "bottom", etc., may be used herein to describe the relationship of one element or feature to another or other elements or features as shown in the drawings. It should be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, an element described as "below" or "beneath" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0092] For brevity and / or clarity, well-known functions or constructions may not be described in detail. As used herein, the phrase "and / or" includes any and all combinations of one or more of the associated listed items.

[0093] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, a first element may be termed a second element, and similarly, a second element may be termed a first element.

[0094] It will be understood that when an element is described as being "on" another element or extending "onto" another element, the element may be directly on the other element or directly extend onto the other element, or there may also be intervening elements. In contrast, when an element is described as being "directly on" another element or "directly" extending onto another element, there are no intervening elements. It will also be understood that when an element is described as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

Claims

1. A RET regulator, comprising: a plurality of drive components, each of which includes a rotatable drive member operatively connected to a respective phase shifter component of a plurality of phase shifter components such that rotation of the drive member adjusts the respective phase shifter component; a first connector coupled to the respective drive member of each of the plurality of drive components, the first connector occupying a first rest position when the respective drive member is stationary, wherein the first connector includes a coupling member mounted on an end of the drive member for reciprocating movement relative to the drive member, the coupling member configured to rotate with the drive member; a drive system including a second connector that occupies a second rest position when the drive system is stationary, the second connector releasably engaging the first connector of each of the plurality of drive components such that actuation of the drive system selectively rotates the drive member, wherein the second connector is configured to reciprocate laterally relative to the plurality of drive components such that the second connector can be selectively aligned with the first connector of each of the plurality of drive components; a spring configured to apply a force on the coupling member, the force biasing the coupling member toward the second connector; and a mechanical calibration system configured to position the second connector at the second rest position.

2. The RET regulator according to claim 1, wherein the drive system includes a drive shaft connected to the second connector and a motor for rotating the drive shaft.

3. The RET regulator according to claim 2, wherein the mechanical calibration system includes a stop member capable of rotating with the second connector.

4. The RET regulator according to claim 3, wherein the mechanical calibration system includes a hard stop that can be engaged by the stop member, wherein when the stop member engages the hard stop, the position of the second connector is a known angular position relative to the second rest position.

5. The RET regulator according to claim 4, further comprising a base station control system including a processor and a memory for storing the known angular position.

6. The RET regulator according to any one of claims 1-5, wherein the drive member includes a lead screw, and a drive nut is threadedly engaged with the lead screw, the drive nut being operatively connected to the respective phase shifter component.

7. The RET regulator according to any one of claims 1-5, wherein the second connector can engage the first connector by linear movement of the drive system relative to the drive member.

8. The RET regulator according to claim 1, wherein the coupling member includes a plurality of engagement structures arranged in a spaced-apart relationship about the axis of rotation of the coupling member.

9. The RET adjuster according to claim 1, wherein the coupling member includes a locking member that engages a fixed locking member to fix the drive member in place, and wherein the spring moves the locking member into engagement with the fixed locking member.

10. The RET adjuster according to claim 9, wherein the engagement of the first connector with the second connector disengages the locking member from the fixed locking member.

11. The RET adjuster according to any one of claims 1-5, wherein the first connector includes a plurality of first engagement structures arranged around the axis of rotation of the first connector, and wherein the second connector includes a plurality of second engagement structures that engage cooperatively with the plurality of first engagement structures on the first connector.

12. The RET adjuster according to claim 11, wherein the plurality of second engagement structures are arranged around the axis of rotation of the second connector.

13. The RET adjuster according to claim 1, wherein the drive system is supported for reciprocating movement transverse to the plurality of drive assemblies such that the second connector can be aligned with any one of the plurality of drive assemblies.

14. The RET adjuster according to any one of claims 1-5, wherein the drive system includes a drive shaft connected to the second connector and a motor for rotating the drive shaft, wherein the drive shaft is supported in a bearing block.

15. The RET adjuster according to claim 14, wherein the drive shaft has a first bevel gear at its end remote from the second connector, the first bevel gear engaging a second bevel gear on the output shaft of the motor.

16. The RET adjuster according to claim 14, wherein the drive shaft has a first section and a second section, the first section being arranged to move linearly relative to the second section.

17. The RET adjuster according to claim 15, wherein the second bevel gear is mounted for reciprocating movement on the output shaft such that the second bevel gear can reciprocate along the output shaft.

18. The RET adjuster according to claim 14, wherein a gear rotates with the drive shaft, the gear selectively engaging a fixed rack such that, in the case of the gear engaging the rack, actuation of the motor causes the drive shaft to reciprocate transversely relative to the plurality of drive assemblies.

19. The RET adjuster according to any one of claims 1-5, wherein the mode selection system moves the drive system between a drive mode, an indexing mode, and a calibration mode.

20. The RET adjuster according to claim 18, wherein the mode selection system moves the drive system such that the first connector engages the second connector and causes the gear to move into engagement with the rack.

21. The RET regulator according to claim 4, wherein the mode selection system moves the drive system between a first position and a second position. In the first position, the stop member is positioned to engage the hard stop. In the second position, the stop member is not positioned to engage the hard stop. When the drive system is in the second position, the first connector engages the second connector.

22. The RET regulator according to claim 4, wherein the mode selection system moves the drive system between a first position, a second position, and a third position. In the first position, the stop member can engage the hard stop. In the second position, the first connector engages the second connector. In the third position, the drive shaft is supported for reciprocating movement transverse to the plurality of drive assemblies such that the second connector can be aligned with any one of the plurality of drive assemblies.

23. The RET regulator according to claim 22, wherein the mode selection system includes a linear reciprocating slide plate that supports the drive system. The movement of the slide plate reciprocates the drive system between the first position, the second position, and the third position. A rack is fixed to the slide plate and is engaged by a pinion driven by a mode selection motor.

24. A multi-RET regulator comprising: a plurality of rotatable drive members, wherein each of the plurality of rotatable drive members is operatively connected to an associated phase shifter assembly such that rotation of the drive member adjusts the associated phase shifter assembly; a plurality of first connectors, one of the plurality of first connectors being coupled to each of the plurality of drive members. When the corresponding drive member is stationary, each first connector occupies a first stationary position. Each first connector includes a coupling member mounted on an end of the corresponding drive member for reciprocating movement relative to the corresponding drive member. Each coupling member is configured to rotate with the corresponding drive member. A drive system includes a second connector that occupies a second stationary position when the drive system is stationary. The second connector releasably engages the first connector of each drive member of the plurality of drive members such that actuation of the drive system selectively rotates the corresponding drive member. The second connector is configured to reciprocate transversely relative to the plurality of rotatable drive members such that the second connector can be selectively aligned with the first connector of each drive member of the plurality of drive members; a spring configured to apply a force on each coupling member that biases the coupling member toward the second connector; and a mechanical calibration system for positioning the second connector at the second stationary position.

25. The multi-RET adjuster according to claim 24, wherein the drive system includes a rotatable drive shaft, the second connector mounted on the drive shaft, and a stop member mounted to rotate with the drive shaft, and a fixed stop, the fixed stop being positioned such that the stop member contacts the fixed stop when the drive system is in a first position.

26. The multi-RET adjuster according to claim 25, comprising a mode selection system that moves the drive system between a first position, a second position, and a third position, wherein in the first position, the stop member is capable of engaging the fixed stop, in the second position, the first connector engages one of a plurality of second connectors, and in the third position, the drive shaft is supported for reciprocating movement transverse to the plurality of drive members such that the second connector can be aligned with any one of the plurality of drive members.

27. The multi-RET adjuster according to claim 25, wherein the second stationary position is a known angular distance from the position of the drive system when the stop member contacts the fixed stop.

28. A method for calibrating a RET regulator, the RET regulator comprising: A movable drive member operatively connected to a phase shifter assembly such that movement of the drive member adjusts the phase shifter assembly; A first connector coupled to the drive member, the first connector occupying a first stationary position when the drive member is stationary, wherein the first connector includes a coupling member mounted on an end of the drive member for reciprocating movement relative to the drive member, the coupling member configured to rotate with the drive member; A drive system including a movable drive shaft and a stop member mounted to move with the drive shaft, the drive shaft supporting a second connector, the second connector occupying a second stationary position when the drive system is stationary; And the second connector is releasably engaged with the first connector such that actuation of the drive system moves the drive member, and a spring configured to apply a force on the coupling member that biases the coupling member toward the second connector; wherein the second connector is configured to reciprocate laterally relative to the movable drive member such that the second connector can be selectively aligned with the first connector, the method comprising: Actuating the drive system to rotate the stop member into engagement with a fixed stop, the fixed stop positioned such that the second connector is in a known position when the stop member contacts the fixed stop; Using the known position to position the second connector at the second stationary position.

29. The method according to claim 28, wherein the known position is the second stationary position.

30. The method according to claim 28 or 29, wherein the known position is a known angular distance from the second stationary position.

31. The method according to claim 28 or 29, wherein actuating the drive system rotates the drive shaft and the stop member.

32. The method according to claim 28 or 29, storing the second rest position in a memory of the base station control system.

33. A method of operating a multi-RET adjuster, the multi-RET adjuster comprising: A plurality of rotatable drive members, wherein each of the plurality of rotatable drive members is operatively connected to an associated phase shifter assembly such that rotation of the drive member adjusts the associated phase shifter assembly; A first connector coupled to each of the plurality of rotatable drive members, the first connector occupying a first rest position when the drive member is at rest, wherein the first connector includes a coupling member mounted on an end of the drive member for reciprocating movement relative to the drive member, the coupling member configured to rotate with the drive member; A drive system including a second connector that occupies a second rest position when the drive system is at rest, the second connector releasably engaging the first connector such that actuation of the drive system moves the drive member; A spring configured to apply a force on the coupling member, the force biasing the coupling member toward the second connector; wherein the second connector is configured to reciprocate laterally relative to the plurality of rotatable drive members such that the second connector can be selectively aligned with the first connector of one of the plurality of rotatable drive members, the method comprising: Moving the second connector laterally with respect to the plurality of rotatable drive members to position the drive system adjacent to one of the plurality of rotatable drive members, the one of the plurality of rotatable drive members being operatively coupled to a phase shifter assembly to be adjusted; Moving the drive system such that the second connector engages the first connector of the one of the plurality of rotatable drive members; Actuating the drive system to adjust the phase shifter assembly.

34. The method according to claim 33, wherein the step of positioning the drive system adjacent to one of the plurality of rotatable drive members comprises: Actuating a first motor to move the rotatable drive member to an indexing mode position; And actuating a second motor to index the drive system laterally with respect to the plurality of rotatable drive members.

35. The method according to claim 34, comprising a rotatable drive shaft connected to the second connector, a gear mounted on the drive shaft to rotate with the drive shaft, the gear engaging a rack when the drive system is in the indexing mode position.

36. The method according to claim 34, wherein the step of moving the drive system includes actuating a first motor to move the drive member to a drive position, and wherein the step of actuating the drive system includes actuating a second motor to rotate a drive shaft connected to the second connector.

37. The method according to claim 34, wherein the step of actuating the drive system includes rotating a lead screw to move a drive nut along the lead screw, wherein the drive nut is operatively connected to the phase shifter.

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