Reflector antenna with a stator portion and a rotor portion rotatable relative to the stator

[0002] This application claims the priority of German Patent Application Serial No. 199 52 817.9, filed Nov. 2, 1999, the subject matter of which is incorporated herein by reference.

[0003] The present invention relates to a reflector antenna with a stator portion and a rotor portion which is supported for rotation relative to the stator portion about a rotation axis, with a reflector secured to the rotor portion and connected by an electrical connection with the stator portion.

[0004] Reflector antennas of this type are used with increasing frequency on moveable vessels, such as ships, for receiving radio signals emitted by satellites. Until now, the electrical connection between the rotor portion and the stator portion has been unsatisfactory, since a fixed connecting cables could not be used between the rotor portion and the stator portion and the electrical antenna signals had to be transmitted instead from the rotor portion to the stator portion by using, for example slip rings. However, slip rings introduce noise in the transmission so that the transmitted signal tends not to be clear. Moreover, the wear of the slip rings strongly affects their performance as evidenced by an increase in the number of interfering signals. Arcing can also falsify the transmitted data, so that a clear reception can no longer be expected.

[0005] It is thus an object of the present invention to provide an improved reflector antenna, obviating the afore-stated drawbacks.

[0006] In particular, it is an object of the present invention to provide an improved a reflector antenna that can transmit radio signals received by the reflector to the stator portion with as little loss and as much clarity as possible.

[0007] These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing the connection as a flexible connecting cable, wherein one end of the cable is attached to the rotor portion and the other end is attached to the stator portion. The end attached to the rotor portion does not move relative to the rotor portion, and the end is attached to the stator portion does not move relative to the stator portion. The ends face one another in the direction of the rotation axis and are connected through a segment of the connecting cables, the respective segment rotating with half the rotation speed of the rotor portion with the same rotation direction as the rotor portion.

[0008] Since the end of the connecting cables that is connected in this manner to the stator portion is tracking, the rotor portion can be connected to the stator portion by a flexible connecting cables. This flexible cables can be implemented as a shielded cables, thereby reducing the losses produced in the connecting cables. Accordingly, the received antenna power available at the output of the reflector antenna is maximized and becomes available in high quality, for example, for providing signals to monitors.

[0009] According to an embodiment of the invention, the rotatable segment of the connecting cables passes through a first guide disposed on a drive wheel that is driven with half the rotation speed of the rotor portion. The rotatable segment of connecting cables is connected to the stator portion before the connecting cables enters the guide, and is connected with the rotor portion after the connecting cables leaves the guide. The connecting cables rotates in the guide with half the rotation speed of the rotor portion. In this way, the desired rotation speed can be precisely maintained, eliminating mechanical stress in the connecting cables.

[0010] According to another embodiment of the invention, the rotatable segment of the connecting cables is guided through a channel of the drive wheel from the center of the drive wheel outwardly towards the circumference of the drive wheel. This arrangement of the drive channel not only reliably guides the rotatable segment of the connecting cables, but also guides the rotatable segment from the stator portion to the rotor portion with a curvature in conformance with design constraints.

[0011] According to another embodiment of the invention, the channel is formed as a bore which surrounds the rotatable segment of the connecting cables with ample clearance so that the connecting cables is movably supported in the bore. In this way, the rotatable segment of the connecting cables is not prevented from performing the necessary compensating motion in order to track the respective rotation of the rotor portion.

[0012] According to another embodiment of the invention, the rotatable segment of the connecting cables extends through a slot in the form of a channel that surrounds the connecting cables with ample clearance. The slot extends radially through the drive wheel. Such slot can be easily produced and can reliably guide the connecting cables.

[0013] According to another embodiment of the invention, the connecting cables includes another section that continuous from the rotatable segment in the direction of the rotor portion and passes through a guide tube. This section that extends into guide tube rotates with the rotor portion with the same rotation direction and the same rotation speed. The guide tube is hence rotatably coupled with the rotating portion. This produces a particularly space-saving arrangement of the connecting cables.

[0014] According to another embodiment of the invention, drive means are provided on the drive wheel for driving the rotor portion that rotates with twice the rotation speed of the drive wheel. In this way, the rotation speed of the rotor portion relative to that of the drive wheel can easily controlled without having to resort to complex drive assemblies.

[0015] According to another embodiment of the invention, the drive means are formed as a shaft that extends through the drive wheel parallel to the shaft of the drive wheel. Drive pinions mesh with teeth disposed on respective ends of the shaft that project from opposing surfaces of the drive wheel. The teeth are connected, on one hand, with the stator portion and, on the other hand, by another pinion with the rotor portion. The drive pinions increase the rotation speed by a ratio of 2:1 relative to the drive wheel. A shaft of this type which extends through the drive wheel with at least one pinion and a deflection pinion for reversing the rotation direction, represents a simple and therefore inexpensive gear that can maintain the ratio of the rotation speed of the rotor portion to the rotation speed of the connecting cables at a value of 2:1. By directly coupling the rotor portion to the drive wheel, the rotation speed ratio is held constant in each phase independent of the rotation speed of the drive wheel. The necessary drive means are inexpensive and can be easily assembled.

[0016] According to another embodiment of the invention, the rotor portion has a first motor that drives the rotor portion relative to the drive wheel. In addition, the drive wheel is driven by a second motor located on the stator portion. With the separate motor drive, the rotor portion and the drive wheel can be driven independently of one another, so that the drive wheel has exactly half the rotation speed of the rotor portion. Moreover, the motors can be easily electrically controlled, thereby eliminating complicated and expensive mechanical controls.

[0017] According to another embodiment of the invention, the two motors are coupled by suitable gears to the rotor portion and the drive wheel, respectively, with the rotor portion being controlled relative to the drive wheel with a ratio of 2:1. Such gears are simple and can be manufactured relatively inexpensively. The rotation speed of the rotor portion can be selected to be exactly half the rotation speed of the drive wheel.

[0018] According to another embodiment of the invention, the two motors are coupled to the drive wheel and the rotor portion, respectively, by toothed belts. Toothed gear drives of this type are particularly simple and easy to maintain. They can also be quickly exchanged and allow precise control of the drive wheel relative to the rotor portion.

[0019] According to another embodiment of the invention, both sides of the toothed belts have teeth, wherein the teeth on one side mesh with the teeth of a drive pinion and the teeth on the other side mesh with the teeth of the rotor portion. By suitably sizing the teeth disposed on the respective toothed belts, a single toothed belt is sufficient to drive the rotor portion in the same rotation direction as the drive wheel with twice the rotation speed.

[0020] According to another embodiment of the invention, the toothed belt engages with the teeth of the rotor portion and after one turn, engages with the teeth of the drive wheel. In this way, two different drive means, i.e., the drive wheel and the rotor portion, respectively, can be driven by deflecting the toothed belt.

[0021] According to another embodiment of the invention, the stator portion as well as the rotor portion include a section formed as a hollow cylinder. Teeth are disposed on the outer surface of the hollow cylinder, whereas the center segment is supported on the inner surface of the hollow cylinder. The drive wheel is supported for rotation relative to the hollow cylinder, so that the two hollow cylinders and the drive wheel form a simple gear which transforms the rotation speeds as desired.

[0022] The connection of the reflector antenna with the hollow cylinder of the rotor portion embodies an advantageous drive for the reflector antenna. A corresponding drive can be used for controlling two antenna movements in the vertical plane, wherein electrical power is supplied by a wire of the connecting cables.

[0023] According to another embodiment of the invention, after the connecting cables exits the channel, the cables s guided to an attachment point of the rotor portion through a tube connected to the drive wheel. The connecting cables is guided in this tube with ample clearance so as to be able to perform a compensating motion conforming to the respective antenna motion.

[0024] According to another embodiment of the invention, the tube is bent in the shape of a gallows that is curved from the exit of the channel of the drive wheel towards a rotation point formed on the rotor portion. The connecting cables passes through the rotation point and extends towards a connecting point formed on the rotor portion, with the ends of the connecting cables being connected to the connecting point. The gallows-like shape precisely guides the connecting cables by preventing the cables from leaving a predetermined passageway when the rotor portion rotates. This ensures that the antenna is guided accurately and without error.

[0025] According to another embodiment of the invention, the tube is bent in the shape of a gallows that is curved from the exit of the channel of the drive wheel towards an attachment point formed in a guide tube connected with the rotor portion. A strand of the connecting cables that exits from the gallows-shaped tube is guided into the guide tube towards the rotor portion. The guide tube allows the attachment point to be moved to a particularly advantageous location which is preferably located on the rotation axis. This enables simple and space-saving guiding of the connecting cables.

[0026] According to another embodiment of the invention, the attachment point of the stator portion is formed as an apex of a dome which is rigidly connected with the stator portion. The connecting cables extends along the walls of the dome from the attachment point to a connecting point. This guide arrangement for the connecting cables is particularly suited for a reflector antenna that is covered by a dome. Guiding the connecting cables along the wall of the dome represents a simple and cost-effective mechanical solution.

[0027] According to another embodiment of the invention, the cross-section of the tube is suitable for receiving at least one connecting cables. In this way, the tube can guide several connecting cables between the rotor portion and the stator portion without causing interference between the various connecting cables due to the rotation of the rotor. Likewise, shielded cables that can include an electric power cables for supplying power to the drive can be commonly guided between the rotor portion and the stator portion.

[0028] According to another embodiment of the invention, the tube is at least partially formed as a flexible spiral wherein the connecting cables can be guided through the unobstructed cross-section of the spiral. In this way, the tube can be easily adapted to the prevailing conditions between the rotor portion and the stator portion.

[0029] According to another embodiment of the invention, the motors can be controlled by a controller, with control signals for a respective vertical and horizontal control of the antenna drives being produced by a comparator circuit. The comparator circuit makes it possible to orient the reflector antenna in a direction where received power optimal.

[0030] According to another embodiment of the invention, horizontal and vertical control signals can be produced by a deviation from the largest possible receivable signal. The reflector antenna will thereby always attempt to move to a region of a highest possible received antenna power.

[0031] According to another embodiment of the invention, eight control signals can be generated for controlling to a motor that control's antenna movements in the perpendicular and horizontal direction, wherein the control signal is produced by changes in the received power of the antenna depending on a ship's motion. In this way, the motor that control the antenna movement in the vertical direction is influenced so as to maintain the reflector antenna always at the most advantageous angular position, where the reflector antenna receives an optimal antenna power, independent of the instantaneous ship movement. This allows for the compensation of the ship's movement.

[0032] The above and other objects, features and advantages of the present invention will be more readily apparent upon reading the following description of preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

[0033] FIG. 1 is a side view of an orientatable antenna;

[0034] FIG. 2 is an enlarged diagram of a gear driving the orientatable antenna;

[0035] FIG. 3 is a longitudinal section through a center segment along the line III—III of FIG. 4;

[0036] FIG. 4 is a top view of a center segment;

[0037] FIG. 5 is a cross-section through a drive wheel along the line V—V of FIG. 6;

[0038] FIG. 6 is a top view of the drive wheel;

[0039] FIG. 7 is a cross-section through a hollow cylinder along the line VII—VII of FIG. 8;

[0040] FIG. 8 is a top view of the hollow cylinder;

[0041] FIG. 9 is a top view of a base plate;

[0042] FIG. 10 is a cross-section through the base plate along the line X—X of FIG. 9;

[0043] FIG. 11 is a top view of a cover plate;

[0044] FIG. 12 is a cross-section through the cover plate along the line XII—XII of FIG. 11;

[0045] FIG. 13 is a side view of another embodiment of an orientatable antenna;

[0046] FIG. 14 is a side view of another embodiment of an orientatable antenna;

[0047] FIG. 15 is a top view of a drive wheel with a toothed belt;

[0048] FIG. 16 is a cross-section through a drive wheel along the line XVI—XVI of FIG. 15; and

[0049] FIG. 17 is a side view of an orientatable reflector antenna.

[0050] Turning now to the drawing, and in particular to FIG. 1, there is shown a connection 3 provided between a stator portion 1 and a rotor portion 2 of an orientatable antenna, with connecting cables 4, 5 extending through the connection 3. The connecting cables 4, 5 can be guided in a tube 6 that has the shape of a gallows 7 and extends from a drive wheel 8 parallel to an interior wall 9 of a dome 10 to an apex 11. From there, the connecting cables 4, 5 which may or may not be jacketed, extend to a receiving element 12 of a reflector antenna 13. The reflector antenna 13 is rotatably supported inside the dome (Radome) 10 for rotation about a vertical axis 14 and a horizontal axis 15. The reflector antenna 13 is rotated about in the vertical axis 14 by a motor 16 that is connected to a driven shaft 17 by a pinion 18 driving a drive wheel 8. The reflector antenna 13 is rotated about the horizontal axis 15 by a belt drive 19 that is driven by a motor 20.

[0051] The motor 20 is fixedly connected to the rotor portion 2 by a cover plate 21 and rotates with the cover plate 21. Conversely, the motor 16 is fixedly connected to the stator portion 1 by a foundation 22, so that the pinion 18 that meshes with the teeth 23 of the drive wheel 8 rotates the drive wheel 8 about the vertical axis 14 when the motor 16 is switched on.

[0052] Referring now to FIGS. 2 to 4, the drive wheel 8 is fixedly connected by a screw connection to a center segment 24 located on the cylindrical outer wall 25. The center segment 24 is penetrated by a center bore 26 that has a narrower cross section in the upper portion facing the rotor portion 2 than the adjacent lower portion 27. The lower portion of the bore 27 includes a conical transition in the direction of the narrower upper portion of the center bore 26. A cross bore 29 is located in the region of the conical transition 28, with the cross bore 29 merging with a channel 30 disposed in the drive wheel 8. As seen in FIG. 6, the channel 30 extends in a horizontal direction from a center point 31 of the drive wheel 8 towards its circumference 33 which has teeth 23. The circumference 33 can also have a smooth surface, without teeth.

[0053] The center point 31 is surrounded by the bore 34 which has a pass fit with the outer wall 25 of the center segment 24 and is furthermore affixed by the ball under a spring force, so that the transverse bore 29 extends in the direction of the channel 30. With this arrangement, a connecting cables 4, 5 that is inserted in the lower portion 27 of the center bore 26, can hence be inserted in the channel 30 through the transverse bore 29 and exit the channel 30 in the direction of the tube 6 of gallows 7.

[0054] A cables feedthrough 35 is attached in the lower portion 27 of the center bore 26 and screwed with a nut 37 to a base plate 36 that forms the stator portion 1. The cables feedthrough 35 cooperates with a bore 38 disposed in the base plate 36, with the connecting cables 4, 5 being guided from the center bore 26 to a bottom side 39 of the base plate facing away from the center bore 26. As seen in FIG. 9, the base plate 36 is secured to the ground by bolts (not shown) extending through four screw holes 40, 41, 42, 43. In addition, the bore 38 is surrounded by a ring having six holes 44, with screws (not shown) extending therethrough into a hollow cylinder 45 that is connected with the base plate 36. As seen in FIG. 11, the hollow cylinder 45 is provided with corresponding threaded holes 50, into which the screws (not shown) extending through the holes 44 are screwed. A guide 51 adapted to receive the connecting cables 4, 5 exiting from the bore 38 extends on the bottom side 39 of the base plate 36.

[0055] The center segment 24 that is driven by the drive wheel 8 is rotatably supported by roller bearings 52, 53 relative to the hollow cylinder 45 that is rigidly connected with the base plate 36. The cylindrical surface 46 of the hollow cylinder 45 has teeth 54. A pinion 55 that is fixedly connected to a shaft 56 extending parallel to the vertical axis 14 meshes with the teeth 54. The shaft 56 extends through the drive wheel 8 and rotates with the drive wheel 8 about the perpendicular axis 14. This arrangement rotates the pinion 55 and the shaft 56 that is rigidly connected to the pinion 55. The shaft 56 is supported in the drive wheel 8 by roller bearings 57, 58.

[0056] The upper end of the shaft 56 that projects from the drive wheel 8, carries an upper pinion 59 that meshes with a deflection pinion 68. This deflection pinion 68 is supported on a axle that extends parallel to the shaft 56 so as to mesh with teeth 16 formed on an upper cylinder 61. The upper cylinder 61 is formed identically to the hollow cylinder. Like the hollow cylinder, the upper cylinder 61 includes threaded bores 50 for connection to a cover plate 62 via screws (not shown). A foundation 63 for the motor 20 is formed on the cover plate 62, with the drive belt 19 of the motor 20 providing the tilt motion of the reflector antenna 13 about the horizontal axis 15.

[0057] The gearing of the pinions 55, 59, 68 and the hollow cylinder 45, 61 is sized so that the cover plate 62 and the cylinder 61 that is fixedly connected with the cover plate 62, which together form the rotor portion 2, rotate with twice the rotation speed as the drive wheel 8. In this way, the tube 6 that is fixedly connected to the drive wheel 8 rotates with half the rotation speed of the rotor portion 2. This arrangement prevents the connecting cables 4, 5 inside the tube 6 from becoming untwisted.

[0058] To adjust the orientation of a reflector antenna 13 relative to a radiation source (not shown), the two motors 16, 20 have to be switched on. By switching on the motor 16, the rotor portion 2 rotates about the vertical axis 16 until the reflector antenna 13 is oriented in the direction of the radiation source. The pinion 18 initiates the rotation of the drive wheel 8. The tube 6 and the connecting cables 4, 5 extending therein also rotate with the drive wheel 8. The connecting cables 4, 5 rotate about a fixed point provided in the cables feedthrough 35 with the same rotation speed as the drive wheel 8. The shaft 56 and the corresponding axle of the pinion 68 also participate in the rotation. Both the shaft 56 and the drive wheel 8 are rotated by the pinion 55 moving on the rotating toothed gear 54. The rotation is also communicated to the two pinions 59, 68 which then rotate the upper cylinder 61. The rotation direction of the deflection pinion 68 is identical to that of the drive wheel 8. However, the rotation speed of the deflection pinion 68 is twice that of the drive wheel 8. The reflector antenna 13 that is fixedly connected to the cover plate 21 has therefore the same rotation direction as the shaft 56.

[0059] The drive wheel can also be driven by a toothed belt that is guided on the circumference 33 of the drive wheel 8 which may or may not have teeth. The toothed belt encircles not only the circumference 33, but also the pinion 18, thereby transmitting the rotation of the pinion 18 to the drive wheel 8. According to the embodiment depicted in FIG. 17, the motor 16 can also be attached to the rotor portion 2, so that the motor 16, when switched on, rotates with the rotation speed of the rotor portion 2 and thereby moves the toothed belt encircling the drive wheel 8.

[0060] The following connecting cable 4, 5 can not only transmit the antenna voltage received from the antenna element 12, but can also supply electric power to the motor 20 and optionally also to the motor 16. The power return line for the motor 20 and optionally also for the motor 16 can be provided along the gallows 7. In addition, as illustrated in FIG. 13, the return line can also be placed on the inner wall 9 of the dome 10. In this case, the transition from the stator portion 1 to the strand 70 of the connecting cables 4, 5 that rotate with half the rotation speed of the rotor portion 2 is located in the fixed apex 72 of the dome 10. This also serves as the attachment point 74 of the stator portion 1. A second strand 71 of the connecting cables 4, 5 extends from this attachment point 74 to a connecting point 90 where the received antenna power exits the dome 10.

[0061] Moreover, the transition between the strand 70 of the connecting cables 4, 5 that rotates with half the rotation speed of the rotor portion 2 and the rotor portion 2 can also be provided in the fixed apex 72 in the region of the attachment point 73. For this purpose, a strand 71 of the connecting cables 4, 5 that extends through a guide to 75, extends from this attachment point 73 in the direction of the rotor portion 2. The guide tube 75 is angled in the direction of the rotor portion 2 and merges with a connecting piece. 89 disposed in a switch box 78 that provides electrical connections for the reflector antenna 13 and the motors 16, 20.

[0062] The motors 16, 20 are controlled in response to the signal power received by the reflector antenna 13. As seen in FIGS. 5 and 6, a sensor 64 is employed for initially orienting the reflector 13 in relation to the respective travel direction of the vehicle as referenced, for example, to a North-South direction. A proximity electrode 65 of the sensor 64 projects in the direction of two pulse generators 66 that are formed with an offset of 180 degrees on a bottom side 67 of the drive wheel 8 and face the sensor 64.

[0063] For example, if a change in the orientation of the stator portion 1 relative to the source power received by the reflector antenna 13 is detected, then the decrease in the power received by the reflector antenna 13 can indicate the number of degrees the reflector antenna 13 has deviated from the direction of optimal reception of the source of radiation. The so determined angle is used to adjust the electric power of at least one of the two motors 16, 20 by an amount corresponding to the number of pulses for the determined angle. A corresponding number of pulse generators 66 is passed by the proximity electrode 65, thereby returning the reflector antenna 13 to a direction optimized for receiving the radiation from the source.

[0064] Likewise, if the reflector antenna 13 is installed on a vehicle, for example a ship, then the course change of the ship can be used to adjust the reflector antenna 13 with the help of the motor 16 to an optimal reception of the radiation emitted by the radiation source. Moreover, the ship's motion about its horizontal axis can be compensated by tracking the reflector antenna 13 about the horizontal axis 15. The motor 20 is controlled accordingly.

[0065] While the invention has been illustrated and described as embodied in a reflector antenna with a stator portion and a rotor portion rotatable relative to the stator, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.