Antenna system for a satellite

Abstract

An antenna system for a satellite is described, comprising a module housing and a coil arranged within the module housing. An antenna substrate is wound onto the coil such that, when the coil is rotated in an unwinding direction, the substrate can be unwound at least section by section, and when the coil is subsequently rotated in the opposite direction, it can be wound at least section by section. The system includes a contacting unit designed to electrically contact the antenna substrate, enabling the receiving of electrical signals from the antenna substrate and / or the transmission of electrical signals into the antenna substrate. The system further includes a motor designed to rotate the coil in the unwinding direction and / or in the winding direction.A satellite with this antenna system is described in the same way.

Description

[0001] Satellites are often equipped with an antenna for wirelessly receiving electromagnetic signals. Such an antenna can also transmit signals in the form of electromagnetic waves. Ultimately, a satellite's antenna enables the transmission of data from a transmitting station to the satellite and vice versa.

[0002] In general, the weight of a satellite, and therefore also the weight of its antenna, should be kept as low as possible. Furthermore, especially in the case of small and microsatellites, which have transported dimensions of just a few cubic decimeters, antennas are needed that take up little space during transport. An example of such microsatellites are the so-called "CubeSats," whose dimensions are usually given in the unit "U." 1 U corresponds to external dimensions of 10 × 10 × 11.25 cm. A single "CubeSat" can be, for example, 2U, 6U, or 12U in size. The packed dimensions of an antenna for such a microsatellite should therefore be as small as possible during transport. However, an antenna must have a certain minimum size for reliable signal reception and / or transmission when used in space.

[0003] To reduce weight and size, a satellite can be equipped with a simple antenna designed for a single transmit and receive frequency. However, its operating range is naturally very limited.

[0004] Antennas with multiple transmit and receive frequencies, on the other hand, are often complex in design, which entails comparatively high costs. Complex antennas are also sometimes prone to failure. Since a satellite cannot be maintained after being launched into space, or only with disproportionately high costs, a satellite antenna should be designed to be as reliable and fail-safe as possible.

[0005] The prior art includes KR 10 1 713 306 B1, CN 1 11 162 368 A, DE 38 87 885 T2 and JP S54 - 33 499 A, which refer to unfoldable booms that can be configured as antennas.

[0006] Against this background, it is an object of the present invention to provide an advantageous antenna system for a satellite. The antenna system according to the invention is defined in the attached claim 1.

[0007] An antenna system for a satellite is provided. The antenna system includes a module housing. The module housing is designed for mounting on the satellite.

[0008] The antenna system further comprises a coil arranged within the module housing. The coil is rotatably mounted about a coil axis relative to the module housing. An antenna substrate is wound onto the coil in such a way that, when the coil is rotated in an unwinding direction, it can be unwound from the coil, at least partially, and that, when the coil is subsequently rotated in the opposite direction, it can be wound up, at least partially.

[0009] The antenna system includes a contact unit that is fixed to the module housing. The contact unit is designed to electrically contact the antenna substrate, allowing electrical received signals to be tapped from the antenna substrate and / or electrical transmitted signals to be fed into the antenna substrate.

[0010] The antenna system includes a motor. The motor is mounted in a rotationally fixed position relative to the module housing. The motor is designed to rotate the coil in the unwinding direction and / or in the winding direction.

[0011] The antenna system is specifically designed for equipping the satellite. The satellite may be a small or microsatellite, for example, with external dimensions of 24 U or less, 16 U or less, or 6 U or less. The antenna system is preferably dimensioned such that it has external dimensions of 1 U or less. The antenna system is particularly designed so that its total weight is less than 1 kg, for example, approximately 750 g.

[0012] The module housing can be designed for direct attachment to the satellite or for attachment to a mounting interface provided on the satellite.

[0013] The coil has, in particular, a first axial end and a second axial end spaced apart from each other along the coil axis. The antenna substrate is preferably wound onto the coil such that it is arranged between the first axial end and the second axial end. The coil may include a first limiting disk, which is essentially perpendicular to the coil axis and extends radially outward from the coil axis. The limiting disk may be located at the first axial end. The coil may also include a limiting ring, which is essentially perpendicular to the coil axis, spaced apart from the coil axis, and extends radially outward with respect to the coil axis. The limiting ring may be located at the second axial end. The coil may have several supports extending between the first axial end and the second axial end, in particular parallel to the coil axis.The supports can each be attached to the limiting disc and the limiting ring. However, it is also conceivable that the coil has a cylindrical support component instead of or in addition to the supports, which extends parallel to the coil axis and is attached, for example, to the limiting disc and the limiting ring. The coil can be formed from the limiting disc, the limiting ring, as well as {i} the supports and / or {ii} the support component. The supports or the support component can carry the substrate wound onto the coil, in particular supporting it in the radial direction. The antenna system can include a bearing (e.g., a ball bearing or a roller bearing) that rotatably supports the coil. The bearing can be attached to the module housing, in particular to an inner surface of the module housing. Preferably, the bearing is arranged inside the coil, i.e., in particular radially inside the coil (e.g.,radially within the wound antenna substrate and / or closer to the coil axis than the supports and / or closer to the coil axis than the support component). An interface can be provided on the boundary plate, which is supported on the module housing via a (e.g., additional) bearing. This additional bearing can be arranged axially spaced from the coil.

[0014] The antenna substrate wound onto the coil can be essentially ribbon-shaped. The wound antenna substrate can form a spiral. A first end section of the antenna substrate can be fixed to the coil. For example, only the first end section of the antenna substrate is fixed relative to the coil. The first end section of the wound antenna substrate can be located radially inward relative to the rest of the antenna substrate (e.g., closer to the coil axis). The antenna substrate can consist of metal or a metal alloy. It is also conceivable that the antenna substrate consists of a plastic or a plastic mixture with embedded conductive particles and / or fibers, where the particles and / or fibers can consist of, for example, carbon, metal, or a metal alloy. As a further alternative, it is conceivable that the antenna substrate consists of a (e.g.,The antenna consists of a dielectric substrate material with an antenna structure attached to it. The substrate material can be made of a plastic or a plastic mixture and / or be reinforced with fibers. For example, the substrate material is a fiber composite. The antenna structure can extend substantially over the entire length of the substrate material. The antenna structure can be made of metal or a metal alloy.

[0015] It is possible, but not necessary, for the entire antenna substrate to unwind from the coil. For example, a section of the antenna substrate (e.g., the first end section) can remain wound onto the coil. It is possible, but not necessary, for the entire antenna substrate to unwind from the coil. For example, a section of the antenna substrate (e.g., a second end section) can remain unwound from the coil.

[0016] For example, the module housing is designed as a Faraday cage. The module housing can be composed of several individual parts connected to each other (e.g., by screws, bolts, or welds), with the individual parts preferably being in electrical contact with each other. The module housing and / or one or more or all of the individual parts of the module housing are preferably made of metal (e.g., aluminum) or a metal alloy (e.g., an aluminum alloy). The module housing can include an electrically conductive coating (e.g., a lacquer) on its outer surface and / or its inner surface. The coating can have a higher electrical conductivity than the underlying material of the module housing.

[0017] The module housing can enclose a substantially enclosed interior. Apart from openings for fasteners (e.g., screws or bolts), a motor shaft, antenna substrate, and / or electrical wiring, the interior can be completely enclosed. In particular, the module housing contains no openings that remain unobstructed during normal operation of the antenna system. The antenna system coil can be located within this interior.

[0018] The motor is preferably an electric motor, in particular a synchronous motor or a reluctance motor. The motor can be a stepper motor. The motor can comprise a motor housing in which a stator and a rotor of the motor are arranged. The motor housing can be designed as a vertical cylinder with a round or non-round (e.g., substantially polygonal) base. The motor is designed, in particular, to drive a drive shaft of the antenna system. The drive shaft can extend along the coil axis and / or along a central (e.g., cylindrical) axis of the motor housing. The drive shaft can be connected to the spindle. In particular, the drive shaft can be attached to the limiting disk.

[0019] For example, the motor is located outside the module housing. The motor can be mounted on the outside of the module housing. The coil can be shielded from the motor by the module housing (e.g., electromagnetically and / or at least radially with respect to the coil axis). The drive shaft can extend to the motor through an opening in the module housing (e.g., a precisely fitting one).

[0020] The module housing may have a recess into which the motor is inserted. For example, the recess may be precisely fitted to the motor housing. The recess and / or the motor may extend at least partially within the coil, in particular radially within the coil (e.g., closer to the coil axis than the support and / or closer to the coil axis than the support component) and / or axially within the coil (e.g., between the first axial end and the second axial end of the coil). The recess and / or the motor may also extend at least partially within the antenna substrate wound onto the coil, in particular radially within the antenna substrate (e.g., closer to the coil axis than the antenna substrate).

[0021] For example, the antenna system is designed such that the antenna substrate extends, at least after partial unwinding from the coil, through an opening in the module housing and out of the module housing. The antenna substrate can be designed such that unwound sections of the antenna substrate assume a predetermined shape, at least after passing through the opening in the unwinding direction. The antenna substrate can be designed as a bistable element, so that unwound sections automatically assume the predetermined shape and / or retain it, at least in microgravity. The predetermined shape can, in particular, be essentially rectilinear and / or have a nonlinear (e.g., curved, U-shaped, or C-shaped) cross-section. The predetermined shape can be essentially trough-shaped.The predetermined shape can be homogeneous and, in particular, the same for all sections of the antenna substrate located outside the opening of the module housing. The opening can have a shape corresponding to the cross-section of the predetermined shape. Thus, the opening can have a shape corresponding to a homogeneous cross-section of a section of the antenna substrate extending from the module housing, in particular the shape of a circular segment.

[0022] The antenna system can be designed such that the antenna substrate, or at least a portion of the antenna substrate located outside the module housing, forms a monopole antenna. Specifically, the antenna substrate and / or the portion of the antenna substrate located outside the module housing is only in electrical contact with the contact unit. All other components of the antenna system that touch the antenna substrate can be electrically insulated.

[0023] The contacting unit can be fixed to the module housing, particularly on an outer surface of the module housing. The contacting unit can also be located outside the module housing. The contacting unit is specifically designed to electrically contact a section of the antenna substrate unwound from the coil (e.g., on the side of the module housing opening facing away from the housing). The contacting unit can be designed to make direct electrical contact with the antenna substrate or to make inductive electrical contact, so that electrical received signals can be tapped from the antenna substrate via the contacting unit and / or electrical transmitted signals can be injected into the antenna substrate. The contacting unit can also be designed to touch the antenna substrate in order to make electrical contact with it.

[0024] The contacting unit comprises a sliding contact that touches the antenna substrate. The sliding contact can be biased towards the antenna substrate so that it is pressed against the substrate with a (e.g., essentially constant) contact pressure. For this purpose, the contacting unit can include a spring element that pushes the sliding contact towards the antenna substrate, or the sliding contact itself can be designed as a spring element. In particular, the sliding contact touches a section of the antenna substrate that is not wound onto the coil.

[0025] The sliding contact can be located outside the module housing. For example, the sliding contact touches the antenna substrate on the side of the module housing opening facing away from the housing.

[0026] For example, the antenna system includes a first mechanical locking device. The first mechanical locking device is designed to allow rotation of the coil in its unwinding direction in a release state and to block rotation of the coil in its unwinding direction in a blocking state. The first mechanical locking device is designed to switch from the release state to the blocking state as soon as a first predetermined portion of the substrate has been unwound from the coil. This first predetermined portion can be the maximum amount of the antenna substrate to be unwound. The first mechanical locking device is, in particular, arranged within the module housing, for example, radially outside the coil. The first mechanical locking device can include a detent element that, in the blocking state, contacts the coil to prevent rotation of the coil in its unwinding direction.In the locked state, the locking element can contact one or more of the supports, the limiting disc, and / or the limiting ring to prevent rotation of the coil in its unwinding direction. In particular, the locking element can be configured such that, in the released state, it contacts a radially outer surface of the antenna substrate wound onto the coil, and in the locked state, it contacts a portion of the coil that was previously located beneath the wound antenna substrate. The locking element's contact with the coil blocks its rotation in its unwinding direction. The first locking device can be reversible. In particular, the first locking device is configured to switch from the locked state to the released state as soon as the first predetermined portion of the substrate is no longer unwound from the coil, i.e., as soon as it is at least partially rewound onto the coil.

[0027] For example, the antenna system includes a second mechanical locking device. The second mechanical locking device is designed to block movement of the substrate in its winding direction when in a locked state. The second mechanical locking device is in the locked state, in particular, when a second predetermined portion of the substrate is wound onto the coil and / or when a section of the antenna substrate located outside the opening falls below a predetermined minimum size. Specifically, the second mechanical locking device is in the locked state when the antenna substrate has not yet been unwound from the coil by the motor. The second mechanical locking device is, in particular, arranged outside the module housing. The second mechanical locking device preferably comprises a [missing information] at an end section (e.g.,A stop element is attached to the second end section of the substrate. The stop element can be configured to make contact with the module housing or a bearing element fixed relative to the module housing as soon as the second predetermined portion of the substrate is wound onto the coil and / or as soon as a section of the antenna substrate located outside the opening falls below a predetermined minimum size. The bearing element can be arranged on an outer surface of the module housing next to and / or around the opening of the module housing. The antenna system can be designed such that when the antenna substrate moves in the winding direction, the stop element is centered in a predetermined spatial position. For this purpose, at least one centering element (e.g., conical, frustoconical, pyramidal, or truncated pyramidal) can be provided on the module housing and / or on the bearing and / or on the stop element.

[0028] The antenna system includes, for example, a detection arrangement designed to detect whether the first blocking device is in its blocking state and / or whether the second blocking device is in its blocking state.

[0029] For example, the detection arrangement comprises a first detection unit designed to detect whether the first locking device is in its locked state. The first detection unit can be configured to detect the spatial orientation of the locking element. In particular, the first detection unit can be configured to detect whether the current spatial orientation of the locking element corresponds to the release state or the locked state of the first locking device. For example, the first detection unit can comprise two electrical contacts designed to make contact with the locking element as soon as the locking element is in a spatial orientation corresponding to the locked state of the first locking device. The locking element can be configured to establish an electrical connection between the two electrical contacts of the first detection unit as soon as it makes contact with them.The first detection unit and / or the electrical contacts of the first detection unit can be arranged on the module housing, in particular on an inner surface of the module housing.

[0030] For example, the detection arrangement includes a second detection unit designed to detect whether the second locking device is in its locked state. The second detection unit can be configured to detect the spatial orientation of the stop element. In particular, the second detection unit can be configured to detect whether the current spatial orientation of the stop element corresponds to the locked state of the second locking device. For example, the second detection unit can include two electrical contacts designed to make contact with the stop element as soon as the stop element is in a spatial orientation corresponding to the locked state of the second locking device. The stop element can be configured to establish an electrical connection between the two electrical contacts of the second detection unit as soon as it makes contact with them.The second detection unit and / or the electrical contacts of the second detection unit can be arranged on the module housing, in particular on an outer surface of the module housing or on the bearing element.

[0031] The antenna system can be designed such that motor operation (e.g., running operation) is interrupted as soon as the detection arrangement detects that the first locking device is in its locked state and / or that the second locking device is in its locked state. The antenna system can also be designed such that motor operation for unwinding the antenna substrate is aborted as soon as the detection arrangement detects that the first locking device is in its locked state. For example, the two electrical contacts of the first detection unit are part of an electrical circuit designed to prevent current from flowing to the motor when and / or as long as these two electrical contacts are electrically connected via the locking element.The antenna system can be designed such that the operation of the motor for winding the antenna substrate is interrupted as soon as the detection arrangement registers that the second blocking device is in its blocked state. For example, the two electrical contacts of the second detection unit are part of an electrical circuit designed to at least temporarily interrupt the current supply to the motor as soon as these two electrical contacts are electrically connected via the locking element.

[0032] For example, the antenna substrate comprises (e.g., more than three) optically detectable position features. These are preferably arranged at predetermined positions on the antenna substrate, with the predetermined positions being spaced apart from one another, particularly along the length of the antenna substrate. For example, the optically detectable position features are arranged at periodic intervals along the length of the antenna substrate (e.g., with a spacing of a few millimeters, e.g., 10 mm). The position features can be located in a (e.g., lateral) edge region of the antenna substrate. The antenna system can include an optical sensor device designed to detect the position of one or more of the position features, particularly relative to the module housing.For example, the optical sensor arrangement is fixed relative to the module housing and designed to detect whether one of the position features is within a detection range of the sensor arrangement. An example of such an optically detectable position feature is a through-hole in the antenna substrate. Another example of such an optically detectable position feature is a section of the antenna substrate that is optically more transparent or more light-reflecting compared to adjacent areas. The sensor arrangement can include a light source and a light detector. For example, the light source and the light detector are arranged such that the antenna substrate unwound from the coil, particularly its edge region, lies in a light path extending from the light source to the light detector.The sensor device can be designed to detect whether a positional feature is located in the light path. The sensor device can be designed as a transmitted light detection system. The light source and the light sensor can be located on opposite sides of the unwound antenna substrate and / or at opposite edges of the module housing opening through which the unwound antenna substrate extends.

[0033] The antenna system may further include a spring element designed to force the coil in its unwinding or winding direction, at least in the event of a motor failure. In particular, the spring element is designed to force the coil in its winding direction, at least as soon as a section of the antenna substrate has been unwound from the coil. Alternatively, the spring element is designed to force the coil in its unwinding direction, at least as long as the antenna substrate has not been unwound from the coil (e.g., until the first mechanical locking device switches to the locking position). The spring element may be arranged within the module housing, for example, within the coil or axially spaced from the coil (e.g., with respect to the coil axis). The spring element may be fixed to the limiting disk by a first spring end section.The spring element can be fixed to the module housing with a second spring end section. The first spring section can be fixed at the interface located on the limiting disc.

[0034] The antenna system can include an actuator unit that is fixed to the module housing and can be switched (e.g., electrically and / or irreversibly) from a transport state to an operating state. The actuator unit is preferably designed to position a locking element in the transport state such that it is in contact with the coil and prevents rotation of the coil. The actuator unit can also be designed to position the locking element in the operating state such that it allows rotation of the coil, for example, by not being in contact with the coil. For instance, in the transport state of the actuator unit, the locking element is in contact with the coil's limiting ring and thereby prevents the limiting ring from rotating around the coil's axis.The limiting ring can have engagement or through-holes, wherein the locking element engages in one or more of these holes when the actuator unit is in transport mode and lies outside these holes when the actuator unit is in operating mode. The actuator unit can include an actuator component made of shape-memory material, which, when the actuator unit is electrically actuated to switch from the transport mode to the operating mode, undergoes a predetermined shape change, thereby releasing and / or causing movement of the locking element. The actuator unit can be located outside the module housing. For example, the locking element or a coupling element connected to the locking element and the actuator unit extends through the module housing, at least when the actuator unit is in transport mode.

[0035] The antenna system may include an electrical circuit. The electrical circuit may be connected to the contacting unit, the motor, the detection arrangement, the optical sensor device, and / or the actuator unit. The electrical circuit may be designed to control the contacting unit, the motor, the detection arrangement, the optical sensor device, and / or the actuator unit. The electrical circuit may be designed to receive and process motor signals, detection signals from the detection arrangement, and / or detection signals from the optical sensor device, in particular to determine the length of the antenna substrate located outside the module housing. In particular, the electrical circuit may be designed to count a number of position features detected by the optical sensor unit. Based on the known spacing of the position features, it is then possible (e.g.,The length of the antenna substrate located outside the module housing can be determined (e.g., via the electrical circuit). The electrical circuit can also be designed to determine the motor's rotational path based on the motor's control signal and / or motor signals. The length of the antenna substrate outside the module housing can then be determined from the motor's rotational path (e.g., via the electrical circuit). To increase the accuracy of the length measurement and / or to increase redundancy, both of the aforementioned approaches can be used in combination. The electrical circuit can have an electrical interface (e.g., a plug connector) designed to be connected to the satellite via a cable. The electrical interface is preferably located outside the module housing. The antenna system can have an antenna connector (e.g.,The antenna connection includes a coaxial cable connector that is electrically connected to the contact element and is designed to be connected to the satellite via a cable connection (e.g., coaxial). The antenna connector is preferably located outside the module housing.

[0036] The motor, electrical circuitry, and / or actuator unit can be attached to a mounting module. The mounting module, together with the components attached to it, can be referred to as a functional assembly. In particular, all active electrical components of the antenna system, such as transistors, LEDs, and photodetectors, can be located outside the module housing and / or attached to the mounting module. The mounting module can be placed on top of the module housing and / or attached to it.

[0037] Furthermore, a satellite with the antenna system will be provided.

[0038] The satellite may be a small or micro satellite, e.g., with external dimensions of 24 U or less, 16 U or less, or 6 U or less. The satellite may have a cable connection that is connected to the electrical interface and / or the antenna connector of the antenna system. The satellite may have a mounting interface designed for attaching the module housing. The satellite may be designed to supply the antenna system with electrical power via the cable connection. The satellite may be designed to transmit control signals to the antenna system via the cable connection, which cause the operation of the motor, in particular the winding or unwinding of the antenna substrate.The satellite can be designed to receive data from the antenna system via the cable connection, indicating the status of the antenna system, in particular the length of the antenna substrate located outside the module housing. The satellite can also be designed to receive electrical signals via the cable connection, which are tapped from the antenna substrate by the contact unit, and / or to transmit electrical signals via the cable connection through the contact unit into the antenna substrate.

[0039] Exemplary embodiments are explained in more detail below with reference to the figures, whereby the same reference numerals denote the same structural and / or functional features unless otherwise indicated. The figures show: Fig. 1. A perspective view of an exemplary antenna system; Fig. 2 a first side view of the antenna system Fig. 1; Fig. 3 a top view of the antenna system Fig. 1; Fig. 4 a second side view of the antenna system Fig. 1; Fig. 5 a cross-sectional view along line BB from Fig. 5; Fig. 6 a cross-sectional view along line AA from Fig. 5; Fig. 7 a perspective view of the module housing of the antenna system Fig. 1; Fig. 8 a perspective view of the coil and the antenna substrate of the antenna system Fig. 1; Fig. 9a-c different views of the functional assembly of the antenna system from Fig. 1; Fig. 10a-d different views of the contacting unit and the bearing element of the antenna system from Fig. 1; Fig. 11a-c different views of the first blocking device of the antenna system from Fig. 1; Fig. 12a-c different views of the stop element of the antenna system from Fig. 1; and Fig. 13 a schematic representation of a satellite with an antenna system.

[0040] In the Fig. Figure 1-12c shows a first exemplary embodiment of an antenna system 100 and of its components. Fig. Figure 13 shows a satellite 400 with this antenna system 100. The satellite 400 can be a small or microsatellite. The antenna system 100 is accordingly compact and has external dimensions of 1 U or less.

[0041] The antenna system comprises a module housing 200 and a functional assembly 300. The module housing 200 is composed of a module base plate 2 and a substantially pot-shaped module housing body 4. The module base plate 2 and the module housing body 4 are attached to one another and are each preferably made of aluminum or an aluminum alloy.

[0042] As particularly in Fig. As shown in Figures 9a-9c, the functional assembly 300 comprises an actuator unit 6 and a mounting module 7, which supports the actuator unit 6. The mounting module 7, in turn, is attached to the module housing body 4. For this purpose, screws are inserted into corresponding mounting holes 8, 9. In the example shown, the mounting module includes an electrical connector 11, an antenna connector 15, which can be configured, for example, as a coaxial interface, and another electrical connector 21. The electrical connector 21 is connected to an electrical circuit of the antenna system 100, while the connector 11 serves in particular to supply power to the electric motor 12. It is also possible to provide the electrical power supply to the motor 12 via the connector 21. In this case, the connector 11 can be configured as shown in Figure 9a-9c. Fig. 2 shown are omitted. The actuator unit 6 may have connecting cables 17 that do not connect to plug contacts 11 or 21. However, it is also possible, as shown in Fig. Figure 3 shows how to route the connecting cables 17 to the plug contact 21 on a side of the mounting module 7 facing the module housing 200.

[0043] The module housing 200 encloses a substantially enclosed interior space 10 and forms a Faraday cage. The module housing 200 can therefore shield components located within the interior space 10 from electromagnetic radiation present outside the module housing 200, in particular electromagnetic radiation with frequencies commonly used for satellite communication (e.g., in the range of a few kilohertz to a few gigahertz).

[0044] The functional assembly 300 further comprises an electric motor 12, which is arranged section by section in a recess 14 of the mounting module 7. Another section of the electric motor 12 projects into a recess 16 of the module housing body 4. This recess 16 is precisely formed to fit an outer surface of the essentially cuboid motor 12, so that the motor 12 is arranged in a rotationally fixed manner with respect to the module housing 200.

[0045] Inside the interior 10 of the module housing 200, a coil 18 is arranged, which is e.g. in Fig. Figure 8 shows that the coil 18 comprises a limiting disk 22 at a first (lower) axial end 20 and a limiting ring 26 at a second (upper) axial end 24, the latter having a plurality of axial through holes 28 distributed substantially uniformly in the circumferential direction. Several supports 30 are provided between the limiting disk 22 and the limiting ring 26, which support the limiting disk 22 and the limiting ring 26 parallel to each other. The supports 30 run substantially parallel to a coil axis 32. A first ball bearing 37 is arranged radially inside the supports 30 and attached to them. Furthermore, an interface 23 is provided axially outside the coil 18 on the limiting disk 22. The interface 23 is connected to the limiting disk 22 and to another ball bearing 39. Both ball bearings 37 and 39 are also fixed to the module housing 200.In this way, the coil 18 is rotatably arranged around the coil axis 32 with respect to the module housing 200.

[0046] The electric motor 12 is designed to rotate the coil 18 about its coil axis 32 via a drive shaft 13. For this purpose, the drive shaft 13 is attached at one distal end to the interface 23.

[0047] A substantially ribbon-shaped antenna substrate 34 is wound onto the coil 18. A first end section 36 of the antenna substrate 34 is attached to one of the supports 30. Starting from this first end section 36, the antenna substrate 34 is wound spirally around the coil. A second end section 38 of the antenna substrate 34 forms the radially outer end of the spiral.

[0048] The antenna substrate 34 is designed as a bistable element, so that after being unwound from the coil 18 it assumes a predetermined shape, at least when it is in microgravity. In particular, antenna substrate unwound from the coil 18 can form a straight boom 3 with a curved cross-section outside the module housing 200, as shown in Fig. Figure 13 is sketched. The boom 3 thus formed then serves as a monopole antenna. For this purpose, the antenna substrate 34 consists of metal or a metal alloy, or of a substrate material which carries a correspondingly conductive antenna structure.

[0049] To tap into electrical voltages induced in the antenna substrate 34 by received electromagnetic waves, a contacting unit 38 is provided. This is, for example, in Fig. Figures 10a-10d show the contacting unit 38. This unit comprises a sliding contact 40, designed as a spring element, which presses against a surface of the antenna substrate 34 with a predetermined contact pressure. In the example shown, this sliding contact 40 is located outside the module housing 200. The contacting unit also includes an electrical circuit board 41 with a coaxial connector 45 mounted on it. The coaxial connector 45 is connected to the sliding contact 40 via an electrical connection provided on the circuit board 41. The coaxial connector 45 can be connected to the antenna terminal 15 and / or an antenna terminal 49 via a (coaxial) cable connection. For example, the two antenna terminals 15 and 49 are electrically connected to each other and configured as a through-wall connection extending through a wall of the mounting module 7.

[0050] The module housing 200 has an outlet opening 42 through which the antenna substrate 34, unwound from the coil 18, extends to the outside. A sliding contact 40 is provided in the area of ​​this outlet opening 42. In the example shown, the antenna system 100 comprises a bearing element 43, which is arranged on a first side of the outlet opening 42 and attached to the module housing body 4 from the outside. The antenna system 100 also comprises a counter block 44, which is arranged on a second, opposite side of the outlet opening 42 and attached to the outside of the module housing body 4. The antenna substrate 34, unwound from the coil 18, is guided through a gap 46 between the bearing element 42 and the counter block 44. The contacting unit 38 is attached to the counter block 44, with the sliding contact 40 on a side of the space 46 facing away from the housing being in contact with the antenna substrate 34.

[0051] The antenna system 100 also includes a first mechanical blocking device 47, which is e.g. in Fig. Figures 11a-11c show the first mechanical locking device 47. It comprises a locking element 48, which is rotatably mounted on a shaft 50 and is pressed towards the axis of rotation of the coil 18 by a spring 52. The locking element rests with a chamfered surface 54 on a radially outer surface 56 of the antenna substrate 34 wound onto the coil 18. As the antenna substrate 34 is unwound from the coil 18, the chamfered surface 54 therefore rubs against the radially outer surface 56 of the antenna substrate. As soon as the antenna substrate 34 is unwound from the coil and exposes an underlying support 30, the locking element 48 rotates around the shaft 50 under spring tension, so that the locking element 48 comes into contact with the exposed support 30.The first locking device 47 is designed such that the locking element 48, in this locked state, prevents further rotation of the coil 18 in the unwinding direction. For example, the locking element 48 can come into contact with an inner wall of the module housing body 4 with a side surface 56 or 58, so that further rotation of the locking element 48 around the shaft 50 is not possible. When the antenna substrate 34 is subsequently wound onto the coil 18, the locking element 48 can rotate back into the released state against the spring tension of the spring 52, so that the chamfered surface 54 again rests on the surface 56 of the antenna substrate 34.

[0052] The antenna system 100 also includes a second mechanical locking device 59, which is formed by the bearing element 42 and a stop element 61. The stop element 61 is, for example, in Fig.Figures 12a-12c show the stop element 61, which is attached to the end section 38 of the antenna substrate 34. In the example shown, the stop element 61 comprises a first stop part 60 and a second stop part 62, which are attached to one another. For fastening, screws can be provided, for example, which are inserted into corresponding screw holes 64. The two stop parts 60, 62 are designed such that the end section 38 of the antenna substrate 34 is clamped between the two stop parts 62, 64. The shape of the clamping surface of the stop element 61 can correspond to the shape of the unwound antenna substrate 34 and, in particular, be essentially trough-shaped. A frustoconical centering element 66 and a hemispherical centering element 68 are provided on the first stop part 60. The bearing element 42 has a corresponding frustoconical recess 70 and a recess 72 that fits the centering element 68.Thus, in the wound state of the antenna substrate 34, a position of the stop element 61 can be determined with respect to the bearing element 42, and thus with respect to the module housing 200, so that further excitation of the antenna substrate 34 or movement of the end section 38 into the module housing 200 is prevented during this blocking state of the second blocking device 59.

[0053] The antenna system 100 also comprises a detection arrangement 74 with a first detection unit 76 and a second detection unit 78. The first detection unit 76 has two electrical contacts 77, 79 arranged on an inner surface of the module housing body 4. The locking element 48 has an electrically conductive coating on the surface 56 or 58 that comes into contact with this inner surface as soon as the first locking device 47 is in the locked state. In this way, a circuit is closed between the two electrical contacts 77, 79 of the first detection unit 76 as soon as the locking element 48 comes into contact with one of the supports 30 of the coil 18 and prevents further unwinding of the coil 18.The closing of the circuit can be detected accordingly in order to conclude that the first blocking device 47 is in a blocking state, and thus also the current length of the boom 3 formed by the unwound antenna substrate 34.

[0054] The second detection unit 78 also has two electrical contacts 80, 82. These are arranged within the frustoconical recess 70. As soon as the frustoconical centering element 66 engages in the recess 70, it comes into contact with the two electrical contacts 80, 82. The centering element 66 has an electrically conductive area which, in this case, closes a circuit between the two electrical contacts 80, 82. The closing of the circuit can be detected accordingly, thus indicating that the antenna substrate 34 is now wound onto the coil 18 as far as possible.

[0055] Depending on the state of the antenna system 100 detected by the detection arrangement 74, further operation of the motor 12 can be prevented. For example, further unwinding of the coil 18 by the motor 12 can be stopped as soon as the first detection unit 76 detects that the first mechanical blocking device 47 is in the blocked state; however, further winding of the coil 18 by the motor 12 can also be stopped as soon as the second detection unit 78 detects that the second mechanical blocking device 59 is in the blocked state.

[0056] The length of the boom 3, formed by the unwound antenna substrate 34 and located outside the module housing 200, can be indirectly determined from a controlled or detected total rotation angle of the motor 12. However, this indirect determination is sometimes inaccurate. Therefore, through-holes 84 are provided at regular intervals along the length of the antenna substrate 34 as optically detectable position markers. For example, each through-hole 84 has a diameter of 1 mm and is offset from adjacent through-holes 84 by 10 mm. The antenna system 100 includes an optical sensor device 86 with a light source in the form of a light-emitting diode 88 and a light detector in the form of a phototransistor 90. The light-emitting diode 88 and the phototransistor 90 are arranged on opposite sides of the unwound antenna substrate 34.For example, the phototransistor 90 is arranged on the bearing element 42 and the light-emitting diode 88 on the mating block 44, or vice versa. The light-emitting diode 88 under the phototransistor 90 is designed such that light emitted by the light-emitting diode 88 towards the antenna substrate 34 can pass through a through-hole 84 in the antenna substrate 34 and onto the phototransistor 90. Ultimately, the optical sensor device 86 thus enables the counting of through-holes 84 in the antenna substrate 34 as they pass by the sensor device 86. Based on the number of through-holes 84 detected in this way and their known mutual spacing, the length of the boom 3 can then be directly determined.

[0057] The antenna system 100 further comprises a spiral spring 92, which is arranged axially opposed to the coil 18 in the module housing 200, immediately adjacent to the limiting disk 22. The spiral spring 92 is fixed at a first spring end 93 in its radially inner region at the interface 23, and at a second spring end 95 in its radially outer region to the module housing 200. The spiral spring 92 is designed such that it forces the coil 18 in its winding direction. In the event of a motor 12 failure, this ensures that the antenna substrate 34 is wound onto the coil 18 without an electrical power supply.

[0058] The actuator unit 6 is designed such that, in a transport state, it positions a pin-shaped locking element 94 in one of the through-holes 28 of the limiting ring 26, thus blocking the coil 18 against rotation about the coil axis 32. Upon an electrically induced (e.g., irreversible) switch of the actuator unit 6 to an operating state, the locking element 94 is pulled out of the through-hole 28, allowing the coil 18 to rotate. The actuator unit 6 can, in particular, be configured as a so-called "pin puller," where the locking element 94 corresponds to the "pin." Examples of such "pin pullers" include the Micro Pin Puller, uD3PP, and the Nano Pin Puller, nD3PP, of the applicant in this patent application.

[0059] The electrical control unit of the antenna system 100 is designed to control the individual components of the antenna system 100, in particular the motor 12, the detection arrangement 74, the actuator unit 6 and the sensor device 86. Preferably, however, signals received via the boom 3 are routed directly to the antenna connection 15, i.e. without signal processing.

[0060] It is understood that this exemplary embodiment can be modified. In particular, the relative dimensions of the individual components shown in the figures can be adapted depending on the intended use and requirements. It is also possible, for example, to adjust the location of the respective components. For instance, it is conceivable that the motor 12 is located entirely outside the coil 18, that the spiral spring 92 is arranged inside the coil 18, and / or that the actuator unit 6 is positioned inside the module housing 200. Furthermore, structural modifications to the individual components, especially to the first locking device 47 and the second locking device 59, are conceivable. Another modification of the antenna system 100 could, for example, consist of arranging the contacting unit 38 inside the module housing 200.It is conceivable that the contacting unit 38 is not in direct contact with the antenna substrate 34, but rather in direct contact with an electrically conductive element attached to the antenna substrate 34. Further modifications are also conceivable.

Claims

[1] Antenna system for a satellite, wherein the antenna system comprises: a module housing designed for attachment to a satellite; a coil arranged in the module housing, which is rotatably mounted about a coil axis with respect to the module housing and on which an antenna substrate is wound in such a way that it can be unwound from the coil at least section by section when the coil is rotated in an unwinding direction and that it can be wound up at least section by section when the coil is subsequently rotated in the opposite direction in a winding direction; a contacting unit fixed to the module housing, designed to electrically contact the antenna substrate so that electrical received signals can be tapped from the antenna substrate via the contacting unit and / or electrical transmitted signals can be fed into the antenna substrate; and a motor which is arranged in a rotationally fixed manner with respect to the module housing and is designed to cause a rotation of the coil in the unwinding direction and / or a rotation of the coil in the winding direction, wherein the contacting unit includes a sliding contact that touches the antenna substrate. [2] Antenna system according to claim 1, wherein the module housing is designed as a Faraday cage and / or encloses a substantially enclosed interior space in which the coil is arranged. [3] Antenna system according to claim 2, wherein the motor is arranged outside the module housing. [4] Antenna system according to claim 3, wherein the module housing has a recess into which the motor is inserted, such that the motor extends at least partially within the coil and / or within the antenna substrate wound on the coil. [5] Antenna system according to one of claims 1 to 4, designed such that the antenna substrate extends, at least after partial unwinding from the coil, through an opening in the module housing and out of the module housing, wherein the opening has a shape corresponding to a homogeneous cross-section of a section of the antenna substrate extending out of the module housing, in particular the shape of a circular segment. [6] Antenna system according to one of claims 1 to 5, wherein the sliding contact touches the antenna substrate on a side of the opening of the module housing facing away from the housing. [7] Antenna system according to any one of claims 1 to 6, further comprising: a first mechanical locking device designed to allow rotation of the coil in its unwinding direction in a release state and to block rotation of the coil in its unwinding direction in a locking state, wherein the first mechanical locking device is designed to switch from the release state to the locking state as soon as a first predetermined proportion of the substrate has been unwound from the coil, wherein the first mechanical locking device preferably comprises a detent element which, in the locking state, contacts the coil to block rotation of the coil in its unwinding direction. [8] Antenna system according to any one of claims 1 to 7, further comprising: a second mechanical blocking device designed to block movement of the substrate in its winding direction when a second predetermined portion of the substrate is wound onto the coil, wherein the second mechanical blocking device preferably comprises a stop element attached to an end section of the substrate, which is configured to come into contact with the module housing or a bearing element fixed with respect to the module housing as soon as the second predetermined portion of the substrate is wound onto the coil. [9] Antenna system according to claim 7 or 8, further comprising a detection arrangement designed to detect whether the blocking device(s) is / are in the blocking state. [10] Antenna system according to claim 9, designed such that operation of the motor is interrupted as soon as the detection arrangement detects that the blocking device(s) is / are in the blocking state. [11] Antenna system according to one of claims 1 to 10, wherein the antenna substrate comprises optically detectable position features at predetermined positions in its longitudinal direction and the antenna system has an optical sensor device designed to detect the position of one or more of the position features relative to the module housing. [12] Antenna system according to one of claims 1 to 11, further comprising a spring element designed to force the coil in its unwinding direction or in its winding direction, at least in the event of a motor failure. [13] Antenna system according to one of claims 1 to 12, further comprising an actuator unit fixed with respect to the module housing and switchable from a transport state to an operating state, which is designed to position a blocking element in the transport state such that it is in contact with the coil and prevents rotation of the coil, and in the operating state to position the blocking element such that it is not in contact with the coil and allows rotation of the coil. [14] Satellite with an antenna system according to any one of claims 1 to 13.

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