Cellular base station antenna system for adjusting a fixed beam elevation

Abstract: An antenna control system enabling the remote variation of antenna beam tilt is disclosed. A drive means (5, 30) continuously adjusts phase shifters (1, 2, 3; 36, 39, 40) of a feed distribution network to radiating elements, to continuously vary antenna beam tilt.

Description: The Technical Field The present invention relates to an antenna control system for varying the beam tilt of one or more antenna. More particularly, although not exclusively, the present invention relates to a drive system for use in an antenna which incorporates one or more phase shifter. Background of the Invention In order to produce downtilt in the beam produced by an antenna array (for example a panel antenna) it is possible to either mechanically tilt the panel antenna or electrically steer the beam radiated from the panel antenna according to techniques known in the art. Panel antennas, such as those to which the present application is concerned, are often located on the sides of buildings or similar structures. Mechanical tilting of the antenna away from the side of the building increases the susceptibility of the installation to wind induced vibration and can impact on the visual environment in situations where significant amounts of downtilt are required. In order to avoid the above difficulties, electrical beam steering can be effected by introducing phase delays into the signal input into radiating elements or groups of radiating elements in an antenna array. Such techniques are described in New Zealand Patent Specification No. 235010. Various phase delay techniques are known, including inserting variable length delay lines into the network feeding to the radiating element or elements, or using PIN diodes to vary the phase of a signal transmitted through the feeder network. JP-A-0 512 191 describes a phase shifter which comprises a circular arc-shaped slider which is slid along a corresponding circular conductor strip. The ends of the conductor strip are then used as output terminals with the arc-shaped slider acting as an input. By moving the slider along the strip, the path length to each of the outputs can be differentially varied. A further means for varying the phase of two signals is described in WO 95/10862 whose disclosure is incorporated herein by reference. This specification describes a mechanically operated variable differential phase shifter incorporating one input and two outputs. GB-A-1314693 describes a phase shifting device formed with telescopic U-shaped conductor sections. Displacement of the telescopic conductor sections may be brought about by cable pulls which are driven by controllable motors. For the present purposes it is sufficient to note that phase shifters such as those described in WO 95/10862 are adjusted mechanically by sliding an external sleeve along the body of the phase shifter which alters the relative phase of the signals at the phase shifter outputs. A typical panel antenna will incorporate one or more phase shifters and the present particular embodiment includes three phase shifters. A signal is input to the primary phase shifter which splits the signal into two signals having a desired phase relationship. Each phase shifted signal is then input into a secondary phase shifter whose outputs feeds at least one radiating element. In this manner a progressive phase shift can be achieved across the entire radiating element array, thus providing a means for electrically adjusting the downtilt of the radiated beam. Other phase distributions are possible depending on the application and shape of the radiated beam. While the steering action is discussed in the context of downtilt of the radiated beam, it is to be understood that the present detailed description is not limited to such a direction. Beam tilt may be produced in any desired direction. Another particular feature of the variable differential phase shifters is that they provide a continuous phase adjustment, in contrast with the more conventional stepped phase adjustments normally found in PIN diode or stepped length delay line phase shifters. In a panel antenna of the type presently under consideration, it is desirable to adjust the entire phase shifter array simultaneously so that a desired degree of beam tilt may be set by the adjustment of a single mechanical setting means. The mechanical drive which performs such an adjustment must result in reproducible downtilt angles and be able to be adapted to provide for a number of different phase shifter array configurations. It is also desirable that the beam tilt of an antenna may be varied remotely to avoid the need for personnel to climb a structure to adjust antenna beam tilt. Disclosure of the Invention It is an object of the present invention to provide a mechanical drive system for use in adjusting mechanical phase shifters which mitigates the abovementioned difficulties, provides a solution to the design requirements of the antennas or antenna arrays described above, or at least provides the public with a useful choice. Accordingly, there is provided a cellular base station antenna system for adjusting a fixed beam elevation, the system comprising: an elongated panel antenna having a front side and a back side, the front side configured to mount first, second, third and fourth radiating elements thereon, the radiating elements configured to produce a beam; a first mechanical phase shifting component mounted on the back side of the panel antenna and including a first transmission line component electrically connected at a first end to one end of a first signal path, the first signal path coupled at an opposite end to the first radiating element, said first transmission line component being connected at an opposed second end to one end of a second signal path, the second signal path coupled at an opposite end to the second radiating element, and a signal-conducting moveable component configured to move along the first transmission line component to shorten the signal path to one of the first and second radiating elements while lengthening the signal path to the other of the first and second radiating elements; a second mechanical phase shifting component positioned on the back side of the panel antenna and including a second transmission line component electrically connected at a first end to one end of a third signal path, the third signal path coupled at an opposite end to the third radiating element, said second transmission line component being connected at an opposed second end to one end of a fourth signal path, the fourth signal path coupled at an opposite end to the fourth radiating element, and a signal-conducting moveable component configured to move along the second transmission line component to shorten the signal path to one of the third and fourth radiating elements while lengthening the signal path to the other of the third and fourth radiating elements; a moveable mechanical linkage interconnecting the moveable components of the first and second phase shifting components, the linkage configured to simultaneously move the moveable components of the first and second phase shifting components such that a fixed elevation of the beam changes in relation to the direction and magnitude of movement of the mechanical linkage; a motor coupled to the mechanical linkage and responsive to a control signal; and a motor controller located remotely from the panel antenna and electrically connected to the-motor, the controller selectively producing a control signal to move the beam from a first fixed elevation to a second fixed elevation. Preferably, the first mechanical phase shifting component includes a shaft with a first threaded portion provided on said shaft and a first cooperating threaded member connected to the first portion of the first mechanical phase shifting component. The second mechanical phase shifting component includes a second threaded portion provided on said shaft and a second cooperating threaded member connected to the first portion of the second mechanical phase shifting component. The arrangement is such that rotation of the shaft causes the first portion of the first mechanical phase shifting component to move relative to a second portion of the first mechanical phase shifting component at a rate of about twice that of the movement of the first portion of the second mechanical phase shifting component relative to the second portion of the second mechanical phase shifting component. Preferably the second threaded member is connected to the second portion of the first mechanical phase shifting component and moves the first portion of the second mechanical phase shifting component via a push rod. This push rod is preferably a coaxial line connecting an output from the first mechanical phase shifting component to the input to the second mechanical phase shifting component. Preferably there is further provided a third mechanical phase shifting component fed from a second output of the first mechanical phase shifting component via a push rod which moves a first portion of the third mechanical phase shifting component in unison with the first portion of the secondmechanical phase shifting component. According to a further aspect of the invention there is provided an antenna system comprising one or more antenna including electromechanical means for varying the downtilt of the antenna and a controller, external to the antenna, for supplying drive signals to the electromechanical means for adjusting downtilt. Preferably the system includes a plurality of antennas and the controller may adjust the downtilt for the plurality of antennas and store the degree of downtilt of each antenna in memory. Preferably the controller may be controlled remotely from a control centre so that a plurality of such systems may be remotely controlled as part of a control strategy for a number of cellular base stations. Preferably the electromechanical means varies the electrical downtilt of each antenna and means are included for monitoring the electromechanical means and providing signals representative of the position of the electromechanical means to the controller. Brief Description of the Drawings Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 : shows a panel antenna incorporating a phase shifter drive mechanism according to a first embodiment of the invention. Figure 2 : illustrates a primary phase shifter incorporating a gear rack. Figure 3 : illustrates an exploded view of the adjustment assembly incorporated into the carriage. Figure 4 : shows diagrammatically the operation of the drive mechanism according to the first embodiment. Figure 5 : shows a panel antenna incorporating a phase shifter drive mechanism according to a second embodiment of the invention. Figure 6 : shows the phase shifter drive mechanism of figure 5 in detail. Figure 7: shows the electrical connection of the motor, switches and reed switch of the drive mechanism shown in figure 6. Figure 8: shows a controller for controlling the drive mechanism shown in figures 6 and 7. Best Mode for Carrying out the Invention Referring to figure 1 there is shown the back side of a panel antenna 4 having a first phase shifter 1, a second phase shifter 2, a third phase shifter 3 and a phase shifter drive mechanism 5. Feed line 6 is connected to input 7 of phase shifter 1. A first portion 8 of phase shifter 1 is moveable relative to a second portion 9 of phase shifter 1. Output signals from phase shifter 1 are supplied via lines 10 and 11 to inputs 12 and 13 of phase shifters 2 and 3 respectively. Feed lines 10 and 11 comprise coaxial push rods which serve the functions both of feeding signals from the outputs of phase shifter 1 to phase shifters 2 and 3 and moving first portions 14 and 15 of phase shifters 2 and 3 relative to second portion 16 and 17 of phase shifters 2 and 3 respectively. Signals output from phase shifters 2 and 3 are supplied via coaxial lines 18, 19, 20 and 21 to be fed to respective radiating elements (not shown). In use first portion 8 of phase shifter 1 may be moved relative to second portion 9 of phase shifter 1 to change the relative phase of signals supplied via lines 10 and 11 to phase shifters 2 and 3 respectively. First portions 14 and 15 of phase shifters 2 and 3 may be moved relative to second portions 16 and 17 of phase shifters 2 and 3 to vary the phase of signals supplied by lines 18, 19, 20 and 21 to respective radiating elements. When phase shifters 1, 2 and 3 are adjusted in the correct respective portions the beam emitted by the antenna can be tilted as required. It will be appreciated that where a less defined beam is required fewer phase shifters may be employed. To achieve even continuous beam tilting for the embodiment shown in figure 1 the first portions 14 and 15 of phase shifters 2 and 3 should move relative to the second portion 16 and 17 of phase shifters 2 and 3 at the same rate. The first portion 8 of phase shifter 1 must however move relative to the second portion 9 of phase shifter 1 at twice this rate. In the arrangement shown second portion 9 of phase shifter 1 is connected to carriage 22. Movement of carriage 22 results in movement of first portions 14 and 15 of phase shifters 2 and 3 via push rods 10 and 11. Referring now to figure 4, operation of the phase shifter drive mechanism will be explained. Second portion 9 of phase shifter 1 is mounted to a carriage 22 which can move left and right. If carriage 22 is moved to the left first portions 14 and 15 of phase shifters 2 and 3 will be moved to the left via push rods 10 and 11. First portion 8 of phase shifter 1 may be moved relative to second portion 9 of phase shifter 1 to vary the phase of signal supplied to phase shifters 2 and 3. According to this first embodiment a rack 23 is secured to first portion 8 of phase shifter 1. Upon rotation of gear wheel 24 first portion 8 of phase shifter 1 may be moved to the left or the right. A smaller gear wheel 25 is secured to and rotates with gear wheel 24. This gear wheel engages with a rack 26 provided on carriage 22. A further gear wheel 27 is provided which may be driven to rotate gear wheels 24 and 25 simultaneously. Gear wheel 24 has 90 teeth whereas gear wheel 25 has 30 teeth. It will therefore be appreciated that rotation of gear wheel 24 results in first portion 8 of phase shifter 1 being moved three times as far as carriage 22 (and hence first portions 14 and 15 of phase shifters 2 and 3). However, as carriage 22 is moving in the same direction as the first portion 8 of phase shifter 1 it will be appreciated that the relative movement between first portion 8 and second portion 9 of phase shifter 1 is twice that of the relative movement between the first and second portions of phase shifters 2 and 3. Accordingly, this arrangement results in the relative phase shift produced by phase shifter 1 being twice that produced by phase shifters 2 and 3 (as required to produce even beam tilting in a branched feed arrangement). The particular arrangement is shown in more detail in figures 2 to 4. It will be appreciated that gear wheel 27 may be driven by any appropriate manual or driven means. Gear wheel 27 may be adjusted by a knob, lever, stepper motor or other driven actuator. A keeper 28 may be secured in place to prevent movement once the desired settings of the phase shifters have been achieved. Referring now to figures 5 and 6, a second embodiment will be described. As seen in figure 5, the arrangement is substantially the same as that shown in the first embodiment except for the drive mechanism 30 employed, which is shown in figure 6. In this embodiment the drive mechanism includes a shaft 31 having a first threaded portion 32 and a second threaded portion 33 provided thereon. A first threaded member 34 is connected to a first portion 35 of primary phase shifter 36. A second threaded member 37 is connected to the second portion 38 of primary phase shifter 36. First threaded portion 32 is of three times the pitch of second threaded portion 33 (e.g. the pitch of the first threaded portion 32 is 6mm whereas the pitch of the second threaded portion is 2mm). In this way, first portion 35 is driven in the direction of movement at three times that of second portion 38. In this way the phase shift produced by primary phase shifter 36 is twice that of second and third phase shifters 39 and 40. Shaft 31 is rotated by motor 41. This may suitably be a geared down 12 volt DC motor. The other end of shaft 31 is supported by end bearing 42. A reed switch 43 is provided to detect when magnets 44 pass thereby. In this way the number of rotations of shaft 31 may be monitored. Limit switches 45 and 46 may be provided so that the motor is prevented from further driving shaft 31 in a given direction if threaded member 34 abuts a lever of limit switch 45 or 46 respectively. Operation of the drive means according to the second embodiment will now be described by way of example. Motor 41 may rotate shaft 31 in an anticlockwise direction, viewed from right to left along shaft 31. Threaded member 37 is driven by second threaded portion 33 to move push rods 47 and 48 to the left, and thus to adjust phase shifters 39 and 40. Threaded member 34 is driven to the left at three times the rate of threaded member 37. First portion 35 thus moves to the left at three times the rate of second portion 38. First portion 35 therefore moves relative to second portion 38 at twice the speed the first portions of phase shifters 39 and 40 move relative to their respective second portions. In this way, delays are introduced in the paths to respective radiating elements so as to produce an evenly tilting beam. The conductivity of reed switch 43 is monitored so that the number of rotations, or part rotations, of shaft 31 may be monitored. If the motor continues driving shaft 31 until threaded member 34 abuts the lever of limit switch 45 then logic circuitry will only permit motor 41 to drive in the opposite direction. Likewise if threaded member 34 abuts the lever of limit switch 46 the motor 41 will only be permitted to drive in the opposite direction. It will be appreciated that the techniques of both embodiments could be employed in antenna arrays using a larger number of phase shifters. In such applications the relative movement of the first portion of each phase shifter relative to the second portion of each phase shifter would decreased by a factor of 2 for each successive phase shifter along each branch. The ratios used may be varied if the radiation pattern of the antenna needs to be altered to account for the directivity of the individual radiating elements and the effect of the back panel as the amount of downtilt is varied. Components of the drive mechanism 30 are preferably formed of plastics, where possible, to reduce intermodulation. Threaded members 34 and 37 preferably include plastic links to phase shifter 36 to reduce intermodulation. It will be appreciated that a number of mechanical drive arrangements may be used to achieve adjustment of the phase shifters in the desired ratio. It is also to be appreciated that sophisticated control electronics may be employed, although the simplicity of construction of the present invention is seen as an advantage. Figure7 shows how motor 41, reed switch 43 and switches 45 and 46 are connected to lines 71, 72, 76 and 77 from an external controller. Lines 71, 72, 76 and 77 are sheathed by conduit 78. Lines 71 and 72 supply current to drive motor 41. Section 73 ensures that if threaded member 34 is driven to either the left-hand side limit or the right-hand side limit it can only be driven in the opposite direction. In the position shown in FIG. 7, switch 45 directly connects line 71 to switch 46 via diode 74. In the position shown switch 46 connects line 71 to motor 41 via diode 75. This is the normal position of the switches when threaded member 34 is not at either extreme limit. When threaded member 34 is driven to the extreme left, for example, and actuates switch 45, then switch 45 open circuits the path via diode 74. Diode 74 allows current flow in the direction allowing motor 41 to drive to the left. Accordingly, when switch 45 is open, motor 41 can only drive in such a direction as to drive threaded member 34 to the right (i.e.: current in the direction allowed by diode 75). via diode 75. This prevents motor 41 driving in such a direction as to drive threaded member 34 further to the right. Lines 76 and 77 are connected to reed switch 43 so that the opening and closing of reed switch 43 may be monitored by an external control unit. In use, the opening and closing of reed switch 43 may be monitored to determine the position of threaded member 34, and hence the corresponding degree of tilt of the antenna. To select an initial angle of downtilt threaded member 34 may be driven to the extreme right. An external controller may provide a current in one direction to motor 41 to drive member 34 to the right. The motor will continue to be driven to the right until threaded portion 34 abuts switch 46. When switch 46 is opened diode 75 will be open circuited, which will prevent the motor being driven further to the right. The controller will sense that threaded member 34 is at its extreme right position as it will detect that reed switch 43 is not opening and closing. After a predetermined delay the controller may then provide a current in the opposite direction via lines 71 and 72 to motor 41 to drive it to the left. As the motor is driven to the left the controller will monitor the opening and closing of reed switch 43 to determine how far threaded member 34 has moved to the left. The controller will continue to move threaded member 34 to the left until reed switch 43 has opened and closed a predetermined number of times, corresponding to a desired angle of downtilt. Alternatively, threaded member 34 may be driven to the extreme left and then back to the right. At an antenna site a number of such panels may be installed and controlled by a single controller 80 as shown in figure 8. The four wires 71, 72, 76 and 77 correspond to respective cable groups 78 to three such antenna panels. Controller 80 may be provided at the base of an antenna site to allow an operator to adjust the tilt of a plurality of antennas at ground level, rather than requiring a serviceman to climb up the antenna structure and adjust each antenna manually. Alternatively, controller 80 may be a hand-held unit which can be plugged into a connector at the base of an antenna to adjust the antenna at a site. Controller 80 may include a display 81, an "escape" button 82, an "enter" button 83, an "up" button 84 and "down" button 85. At power up display 81 may simply display a home menu such as "Deltec NZ © Ltd 1995". Upon pressing any key, a base menu may be displayed including options such as: unlock controls set array tilt measure tilt enable array disable array lock controls The up/down keys may be used to move through the menu and the enter key 83 used to select an option. If "unlock controls" is selected a user will then be required to enter a three digit code. The up/down keys may be used to move through the numbers 0 to 9 and enter used to select each number. If the correct code is entered "locked released" appears. If the incorrect code is entered "controls locked" appears and a user is returned to the home menu. If "set array tilt" is selected from the base menu the following may appear: set array tilt array:0 1 X.X° The up-down keys 84, 85 may be used to select the desired array number. The enter key accepts the selected array and the previously recorded angle of downtilt may be displayed as follows: set array tilt array: 01 4. 6 ° In this example the previously set angle of downtilt with 4.6°. Using the up/down keys 84,85 a new angle may be entered. Controller 80 may then provide a current to motor 41 via lines 71 and 72 to drive threaded portion 34 in the desired direction to alter the downtilt. The opening and closing of reed switch 43 is monitored so that threaded member 34 is moved in the desired direction for a predetermined number of pulses from reed switch 43. The downtilt for any other array may be changed in the same manner. If the controller is locked a user may view an angle of downtilt but will not be able to alter the angle. If the "measure array" option is selected the present angle of downtilt of the antenna may be determined. Upon selecting the "measure tilt" function from the base menu, the following display appears: measure tilt array: 0 1 X.X° The up/down buttons may be used to select the desired array. The enter key will accept the selected array. To measure the actual angle of downtilt controller 80 drives a motor 41 of an array to drive member 34 to the right. Motor 41 is driven until threaded member 34 abuts switch 46. The controller 80 counts the number of pulses from reed switch 43 to determine how far threaded portion 34 has travelled. At the extreme right position the controller 80 determines and displays the angle of downtilt, calculated in accordance with the number of pulses connected from reed switch 43. The controller 80 then drives threaded member 34 back in the opposite direction for the same number of pulses from reed switch 43 so that it returns to the same position. The angle of downtilt for each antenna may be stored in memory of controller 80. This value will be updated whenever the actual angle of downtilt is measured in this way. The "measure tilt" function may not be used if the controller is locked. Controller 80 may include tables in memory containing the number of pulses from reed switch 43 that must be counted for threaded member 34 to achieve each desired degree of downtilt. This may be stored as a table containing the number of pulses for each required degree of downtilt, which may be in .1° steps. This approach ensures that any non-linearities of the antenna may be compensated for as the tables will give the actual amount of movement required to achieve a desired downtilt for a given antenna. The "enable array" function may be used to enable each array when installed. The controller 80 will be prevented from moving any array that has not been enabled. Controller 80 will record in memory which arrays have been enabled. The "disable array" function may be used to disable arrays in a similar manner. The "lock controls" function may be used to lock the controller once adjustment has been made. A "rack error" signal may be displayed if the array has not operated correctly. This will indicate that an operator should inspect the array. Adjustment of the array may also be performed remotely. Controller 80 may be connected to modem 86 via serial line 87 which may connect via telephone line 88 to a central controller 89. Alternatively, the controller 80 may be connected to a central controller 89 via a radio link etc. The functions previously discussed may be effected remotely at central controller 89. In a computer controlled system adjustments may be made by a computer without operator intervention. In this way, the system can be integrated as part of a control strategy for a cellular base station. For example, a remote control centre 89 may adjust the downtilt of antennas at a cellular base station remotely to adjust the size of the cell in response to traffic demand. It will be appreciated that the capability to continuously and remotely control the electrical downtilt of a number of antenna of a cellular base station may be utilised in a number of control strategies Central controller 89 may be a computer, such as an IBM compatible PC running a windows based software program. A main screen of the program may show information regarding the antenna under control as follows: GROUP 1 NAME TYPE CURRENT ANGLE NEW VALUE STATUS antenna 1 1 south VT01 12° 12.5° setting antenna 2 1 north VT01 12° 12.5° queued antenna 3 1 west VT01 12 ° 12.5° queued GROUP 2 NAME TYPE CURRENT ANGLE NEW VALUE STATUS antenna 4 2 south VT01 6° pending antenna 5 2 north VT01 6 ° .5° nudging antenna 6 2 west VT01 6° faulty The antennas may be arranged in groups at each site. Group 1 for example contains antennas 1, 2 and 3. The following information about each antenna is given Name : this is the user assigned name such as 1 south, 1 north, 1 west etc. Type : this is the antenna type which the controller communicates to the PC at start-up. Current Angle : this is the actual degree of beam tilt of an antenna which is communicated from the controller to the PC at start-up. The controller also supplies to the PC each antenna's minimum and maximum angles of tilt. New Value : by moving a pointer to the row of an antenna and clicking a button of a mouse the settings of an antenna may be varied. When a user clicks on the mouse the following options may be selected: Name - the user may change the group or antenna name. Adjust - a user may enter a new angle in the "new value" column to set the antenna to a new value. Nudge - the user may enter a relative value (i.e.: increase or decrease the tilt of an antenna by a predetermined amount). Measure - the controller may be instructed to measure the actual angle of tilt of an antenna or group of antennas. If an antenna is in a "fault" condition then it may not be adjusted and if a user clicks on a mouse when that antenna is highlighted a dialogue box will appear instructing the user to clear the fault before adjusting the antenna. Each antenna also includes a field indicating the status of the antenna as follows: O.K. - the antenna is functioning normally. Queued - an instruction to read, measure, set or nudge the antenna has been queued until the controller is ready. Reading - when information about an antenna is being read from the controller. Measuring - when the actual degree of tilt of the antenna is being measured. Setting - when a new tilt angle is being set. Nudging - when the tilt angle of the antenna is being nudged. Faulty - where an antenna is faulty. When adjusting, measuring or nudging an antenna a further dialogue box may appear describing the action that has been instructed and asking a user to confirm that the action should be taken. This safeguards against undesired commands being carried out. Information for a site may be stored in a file which can be recalled when the antenna is to be monitored or adjusted again. It will be appreciated that the software may be modified for any required control application. Controller 80 may be a fixed controller installed in the base of an antenna site or could be a portable control unit which is plugged into connectors from control lines 78. Where in the foregoing description reference has been made to integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth. Industrial Applicability The present invention may find particular application in antenna systems, such as those used in cellular communication systems.

Claims: A cellular base station antenna system for adjusting a fixed beam elevation, the system comprising: an elongated panel antenna (4) having a front side and a back side, the front side configured to mount first, second, third and fourth radiating elements thereon, the radiating elements configured to produce a beam; a first mechanical phase shifting component (1) mounted on the back side of the panel antenna and including a first transmission line component (9) electrically connected at a first end to one end of a first signal path (10), the first signal path coupled at an opposite end to the first radiating element, said first transmission line component being connected at an opposed second end to one end of a second signal path (11), the second signal path coupled at an opposite end to the second radiating element, and a signal-conducting moveable component (8) configured to move along the first transmission line component to shorten the signal path to one of the first and second radiating elements while lengthening the signal path to the other of the first and second radiating elements; a second mechanical phase shifting component (2,3) positioned on the back side of the panel antenna and including a second transmission line component (16,17) electrically connected at a first end to one end of a third signal path (18,20), the third signal path coupled at an opposite end to the third radiating element, said second transmission line component being connected at an opposed second end to one end of a fourth signal path (19,21), the fourth signal path coupled at an opposite end to the fourth radiating element, and a signal-conducting moveable component (14,15) configured to move along the second transmission line component to shorten the signal path to one of the third and fourth radiating elements while lengthening the signal path to the other of the third and fourth radiating elements; a moveable mechanical linkage (23-27,33,37) interconnecting the moveable components of the first and second phase shifting components, the linkage configured to simultaneously move the moveable components of the first and second phase shifting components such that a fixed elevation of the beam changes in relation to the direction and magnitude of movement of the mechanical linkage; a motor (41) coupled to the mechanical linkage and responsive to a control signal; and a motor controller (80) located remotely from the panel antenna and electrically connected to the motor, the controller selectively producing a control signal to move the beam from a first fixed elevation to a second fixed elevation. The antenna system of claim 1 wherein a. the elongated panel antenna is adapted to be mounted vertically and further comprises: i. a feed system configured to supply signals to an arrangement of the spaced first, second, third and fourth radiating elements on the front side of the panel antenna; and ii. an electromechanical phase adjustment system comprising: 1. the first mechanical phase shifting component (1) located in said feed system; 2. the second mechanical phase shifting component (2,3) located in said feed system; and 3. the motor (41) mechanically coupled to said moveable mechanical linkage such that energizing said motor moves said linkage, and b. a beam elevation control system comprising: i. the motor controller (80) located at the base of an antenna site and connected to said motor, said motor controller configured to send beam elevation commands to said motor to effect adjustments in beam elevation; ii. a central controller (89) located remotely from said motor controller (80) and coupled to said motor controller. The antenna system of claim 1 or 2 wherein the mechanical linkage (23-27,33,37) includes an arrangement for converting between rotary and linear movement. The antenna system of any one of claims 1 to 3 wherein the mechanical linkage includes an elongated member extending lengthwise along a portion of the panel antenna and located between the motor and the moveable components of the first and second phase shifting components. The antenna system of any one of claims 1 to 4 wherein the mechanical linkage is configured to move the moveable components of the first and second phase shifting components at different rates. The antenna system of any one of claims 1 to 5 wherein the mechanical linkage is configured to move the moveable component of one of the first and second phase shifting components at twice the rate relative to the moveable component of the other of the first and second phase shifting components. The panel antenna of claim 1 or 2 wherein the mechanical linkage includes an elongated member extending lengthwise along a portion of the panel antenna and located between the motor and the moveable components of the first and second phase shifting components, and wherein the motor (41) is a stepper motor having a rotary output shaft (31) drivingly coupled to the elongated member by a threaded element (32, 33) which advances and retracts the elongated member in the longitudinal direction. The system of claim 1 or 2 wherein the mechanical linkage includes an elongated member extending lengthwise along a portion of the panel antenna and located between the motor and the moveable components of the first and second phase shifting components, and wherein the coupling between the motor and the mechanical linkage converts rotary movement of the motor to linear movement of the elongated member in the lengthwise direction along the panel antenna. The system of any one of claims 1 to 8 wherein said motor controller is adapted to adjust a phasing of signals supplied to at least selected radiating elements so as to cause a predetermined increase in a downtilt angle of the beam or a predetermined decrease in a downtilt angle of the beam. The system of any one of claims 1 to 9 wherein said motor controller is adapted to measure a phase value of signals supplied to at least some of the radiating elements The system of any one of claims 1 to 10 wherein said motor controller is adapted to identify a status of said antenna. The system of any one of claims 1 to 11 further including a user interface operatively coupled to the controller, wherein the user interface permits actions selected from the group of actions consisting of a) selecting one of a plurality of antennas, b) setting an antenna beam angle, c) nudging an antenna beam angle, d) resetting an antenna beam angle, e) measuring an antenna beam angle, f) enabling an antenna, g) disabling an antenna, h) locking controls of the user interface, and i) unlocking controls of the user interface. The system of any one of claims 1 to 12 further including a user interface operatively coupled to the controller, wherein the user interface provides indications selected from the group of indications consisting of a) the antenna beam angle could not be set, b) the antenna beam angle could not be measured, c) the antenna could not be enabled, d) the antenna could not be locked, e) the controller was not able to communication with the antenna, f) motor failure, g) an antenna error has occurred, h) the antenna could not be nudged, and i) the antenna is functioning normally. The system of any one of claims 1 to 13 wherein data corresponding to antenna beam angle parameters is stored in a file accessible by the controller. The system of any one of claims 1 to 6 wherein said motor is a stepper motor. The system of any one of claims 1 to 6 wherein said motor is a stepper motor, and wherein said controller supplies a predetermined number of drive pulses to said motor. The system of any one of claims 1 to 16 wherein said motor controller is a personal computer. The system of any one of claims 1 to 17 wherein said motor controller is located at a base of an antenna site and connected to the motor by wires, the controller selectively producing a control signal to move the beam from a first fixed elevation to a second fixed elevation. The system of claim 1 including a second controller (89) located remotely from, and coupled to said motor controller (80), the motor controller being responsive to commands produced by the second controller. An apparatus comprising a plurality of antenna systems as defined in claim 1 wherein a common motor controller (89) controls the motors (41) of each of said systems. An apparatus comprising a plurality of antenna systems as defined in claim 2 wherein a common beam elevation control system controls the motors (41) of each of said cellular base station antenna systems.

Inventors: EHLEN MATHIAS MARTIN ERNEST, HEINZ WILLIAM EMIL, EHLEN, MATHIAS MARTIN ERNEST, HEINZ, WILLIAM EMIL
Applicants: ANDREW CORP, ANDREW CORPORATION
Application year: 1995
Main classification: H01Q3
IPC codes: H01Q1, H01Q3, H01Q21