Patent Description:
Satellite communication systems typically include one or more satellites and a set of ground terminals. Such systems typically operate within regulations that allocate operating frequency bandwidth for a particular communications service. Satellites with embedded digital telecommunications payloads can provide advanced features such as reconfigurable switching, beamforming or beam hopping with a high degree of flexibility. Antennas may be provided on a satellite for transmitting and/or receiving RF signals. An example of an antenna includes a reflector and a feed assembly that may include one or more feed horns. In some cases, a steerable antenna may include a reflector that can be reoriented in space to redirect RF signals (e.g., to change target areas) without reorienting the satellite. <CIT> discloses a multibeam antenna with adjustable pointing. <CIT> discloses mechanisms for orienting and placing articles. <CIT> discloses a twodimensional movement closed-link structure. <CIT> discloses an oscillating device.

According to a first aspect of the present invention there is provided an apparatus as claimed in claim <NUM>. Aspects of the present technology may be applied to spacecraft such as satellites used for various purposes including but not limited to communication. In many satellites, including satellites used for digital communication (e.g., including a digital channelizer and/or other digital circuits) and analog communication, one or more spot beams are used for communication between a satellite and a target area of the earth's surface. A spot beam may include RF signals sent to and/or received from a target area by an antenna. The antenna may include a feed horn and a reflector (e.g., a parabolic reflector). A steerable antenna may allow redirection of the spot beam to different target areas. Antennas may also be used on Earth (terrestrial antennas) for communication with satellites and/or for communication with other locations on Earth. While examples below refer to specific examples, the present technology is not limited by location (e.g., to satellite antennas) or to antennas used for any specific purpose (e.g., for providing network access).

Aspects of the present technology enable reorienting one or more spot beams generated by an antenna independently, without moving an antenna reflector by moving one or more corresponding feed horns. Where two or more feed horns are provided in an antenna to support two or more spot beams, each spot beam may be individually redirected (e.g., one spot beam may be redirected without affecting other spot beams of the same antenna) using individually movable feed horns.

A movable feed horn assembly includes a feed horn attached to a planar five bar linkage at or near the endpoint of the planar five bar linkage to enable movement of the feed horn along a plane, with actuators (motors) attached to the planar five bar linkage (on either side of its ground link) to control the location of the feed horn. An antenna may include two or more movable feed horn assemblies that allow respective spot beams to be redirected without moving the reflector. The antenna may also include one or more feed horns that do not move.

Aspects of the present technology may be implemented in a single satellite, in multiple satellites (e.g., in a satellite communication system) or in other locations (including on Earth). A satellite communication system may include a single satellite or a constellation of geostationary or non-geostationary satellites orbiting the Earth to cover one or more regions of the Earth. The satellite communication system may further include components on Earth including, for example, a plurality of gateways GWs and a plurality of subscriber terminals STs (also referred to as terminals). A satellite may enable communication between different points on the ground. For example, the subscriber terminals STs may communicate with the gateways GWs or with other terminals via the satellites. The system can be used to provide access to the Internet or other network, telephone services, video conferencing services, private communications, broadcast services, as well as other communication services.

In general, each satellite provides a plurality of receive and transmit beams which may be formed by analog means such as non-articulated or steerable spot beam antenna, or by analog beamforming networks at the input or output sides of the satellite operating on antenna element signals. The entirety or portions of the spectrum covered by receive beams (receive sub-bands) are routed to the entirety or portions of the spectrum covered by transmit beams (transmit sub-bands). This routing is traditionally performed by analog means (bent pipe payloads). Alternatively, onboard processing can be used to flexibly assign receive sub-bands to transmit sub-bands using a digital channelizer system, which may or may not include beam hopping schemes. Additionally, the digital channelizer system may also be used to form the beams digitally, in which case it will receive as input an array of receive antenna element signals and output an array of transmit antenna element signals. Mixed operating modes are also possible where some of the beams are formed analogically and other beams are formed digitally. Any given beam may also be formed by a combination of analog and digital means (partial analog beamforming). Aspects of the present technology are applicable to satellites using a bent pipe configuration, satellites using a digital channelizer, and satellites using mixed operating modes.

<FIG> is a block diagram depicting a portion of a satellite communications system that includes one or more satellites. <FIG> depicts satellite <NUM>, which may be a geostationary satellite or a non-geostationary satellite. A geostationary satellite moves in a geosynchronous orbit (having a period of rotation synchronous with that of the Earth's rotation) in the plane of the Equator, so that it remains stationary in relation to a fixed point on the Earth's surface. This orbit is often achieved at an altitude of <NUM>,<NUM> miles (<NUM>,<NUM>) above the earth; however, other altitudes can also be used. A non-geostationary satellite is a satellite that is not a geostationary satellite and is not in an orbit that causes the satellite to remain stationary in relation to a fixed point on the Earth's surface. Examples of non-geostationary satellites include (but are not limited to) satellites in Low Earth Orbits ("LEO"), Medium Earth Orbits ("MEO") or Highly Elliptical Orbits ("HEO"). Although <FIG> only shows one satellite, in some embodiments, the system will include multiple satellites that are referred to as a constellation of satellites, which may communicate with each other either in a single direction or bi-direction.

In one embodiment, satellite <NUM> comprises a bus (i.e., spacecraft) and one or more payloads, including a communications payload (e.g., payload <NUM> and bus <NUM> of <FIG>). The satellite <NUM> may also include multiple power sources, such as batteries, solar panels, and one or more propulsion systems, for operating the bus and the payload (e.g., bus <NUM> and payload <NUM>). The satellite <NUM> includes an antenna system that provides a plurality of beams, including non-articulated and steerable spot beams, for communicating with ground terminals such as subscriber terminals STs and/or gateways GWs.

A subscriber terminal ("ST") is a device that wirelessly communicates with a satellite, usually to be used by one or more end users. The term subscriber terminal ST may be used to refer to a single subscriber terminal ST or multiple subscriber terminals STs. A subscriber terminal ST is adapted for communication with the satellite communication system including satellite <NUM>. Subscriber terminals STs may include fixed and mobile subscriber terminals STs including, but not limited to, a cellular telephone, wireless handset, a wireless modem, a data transceiver, a paging or position determination receiver, or mobile radio-telephone, a cellular backhaul, a trunk, an enterprise computing or storage device, an airborne device, a maritime device, or a head end of an isolated local network. A subscriber terminal ST may be hand-held, portable (including vehiclemounted installations for cars, trucks, boats, trains, planes, etc.) or fixed as desired. A subscriber terminal ST may be referred to as a wireless communication device, a mobile station, a mobile wireless unit, a user, a subscriber, a terminal or a mobile.

The term gateway ("GW") may be used to refer to a device that communicates wirelessly with a satellite and provides an interface to a network, such as the Internet, a wide area network, a telephone network or other type of network. In some embodiments, gateways GWs (e.g., GW <NUM>, <NUM>, <NUM>, <NUM> of <FIG>) manage the subscriber terminals STs.

<FIG> also shows a Network Control Center <NUM>, which includes an antenna and modem (not shown) for communicating with satellite <NUM>, as well as one or more processors and data storage units (not shown). In some embodiments, Network Control Center <NUM> provides commands to control and operate satellite <NUM>, as well as all other satellite communication payloads in the constellation. Network Control Center <NUM> may also provide commands to any of the gateways GW (via a satellite or a terrestrial network) and/or subscriber terminals ST. While specific components are shown in <FIG>, additional components, or different components may be used in other examples and the present technology is not limited to any particular satellite system configuration.

For example purposes only, <FIG> shows five spot beams: <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. Spot beam <NUM> is a steerable spot beam that broadcasts a signal over target area <NUM> (target area) for communicating with one or more gateways GWs <NUM> via downlink 202d and uplink 202u (e.g., downlink 202d may comprise data packets from one or more Internet servers that are transferred via gateway GW <NUM> to one or more subscriber terminals STs and uplink 202u may comprise data packets from one or more subscriber terminals STs that are transferred to Internet servers via gateway GW <NUM>). Spot beam <NUM> is a steerable dual-purpose beam that broadcasts a signal over target area <NUM> in order to communicate with one or more gateways GWs <NUM> and one or more subscriber Terminals STs via downlink 206d and uplink 206u. Spot beam <NUM> is a steerable spot beam that could be used to communicate with gateways GWs and/or subscriber terminals STs, but in the example of <FIG> spot beam <NUM> broadcasts a signal over target area <NUM> to communicate with one or more gateways GWs <NUM> via downlink 210d and uplink 210u. The two hundred spot beams that perform time domain beam hopping can be used to communicate with subscriber terminals STs and/or gateways GWs. Spot beams <NUM> and <NUM> are two examples of the two hundred non-articulated spot beams that performed time domain beam hopping. Spot beam <NUM> broadcasts a signal over target area <NUM> to communicate with one or more gateways GWs <NUM> and one or more subscriber terminals STs via downlink 214d and uplink 214u. Spot beam <NUM> broadcasts a signal over target area <NUM> to communicate with subscriber terminals STs via downlink 218d and uplink 218u.

<FIG> is a block diagram of one embodiment of satellite <NUM> of <FIG>. In one embodiment, satellite <NUM> includes a bus <NUM> and a payload <NUM> carried by bus <NUM>. Some embodiments of satellite <NUM> may include more than one payload <NUM>. The payload <NUM> provides the functionality of the communication and/or processing systems described herein (e.g., payload communication circuit <NUM>, payload processing system <NUM> and TC&R communication circuit <NUM>).

In some embodiments, bus <NUM> is a spacecraft that provides power for the payload <NUM> and controls position of the satellite (e.g., to maintain a satellite in a given orbit with a given orientation). For example, the bus components include a power controller <NUM>, which may be connected to solar panels (not shown) and one or more batteries (not shown in <FIG>) to provide power to other satellite components including command & data handling circuit (CD&H) <NUM>, thermal control circuit <NUM>, attitude determination and control circuit <NUM> and propulsion <NUM>. Other equipment can also be included. Solar panels, batteries (not shown) and power controller <NUM> are used to provide power to satellite <NUM>. Thrusters (not shown) as part of propulsion <NUM> are used for changing the position or orientation of satellite <NUM> while in space. Attitude sensors (e.g., part of determination & control circuit <NUM>) may be used to determine the position and orientation of satellite <NUM>. T, C & R communication circuit <NUM> includes communication and processing equipment for telemetry, commands from the ground to the satellite and ranging to operate the satellite. CD&H <NUM> is used to control and operate satellite <NUM>. An operator on the ground can control satellite <NUM> by sending commands via T, C & R communication circuit <NUM> to be executed by a system processor (e.g., as part of CD&H <NUM>). In one embodiment, CD&H <NUM> is in communication with payload <NUM>.

In one embodiment, the payload <NUM> includes an antenna system that may be connected to payload communication circuit <NUM> and TC&R communication circuit <NUM> (e.g., as shown in <FIG>, not depicted in <FIG>) that provides a set of one or more beams (e.g., spot beams) comprising a beam pattern used to receive wireless signals from ground stations, and to send wireless signals to ground stations and/or other satellites. In one example, an entire service region is covered using one beam. In another example, however, the antenna system provides a beam pattern that includes multiple spot beams, with each spot beam covering a portion of the service region. The portion of the service region covered by a spot beam is referred to as a cell. The individual spot beams divide an overall service region into a number of cells. In one embodiment, the antenna system includes a phased array antenna, a direct radiating antenna, or a multi-feed fed reflector.

In some embodiments, Payload <NUM> also includes payload components such as payload communication circuit <NUM>, TC&R communication circuit <NUM> and Payload Processing System <NUM>. Payload communication circuit <NUM> and TC&R communication circuit <NUM>, which are connected to the antenna system (not depicted), are configured to communicate with one or more ground terminals (e.g., send and receive messages to/from gateways GWs and/or subscriber terminals STs).

<FIG> is a block diagram depicting one embodiment of an antenna system of satellite <NUM>. For example, <FIG> shows antennas <NUM>, <NUM>, <NUM> and <NUM> which provide the multiple spot beams. Each of antennas <NUM>, <NUM>, <NUM> and <NUM> provide a cluster of spot beams each. <FIG> shows feed cluster <NUM> pointed at antenna <NUM>, feed cluster <NUM> pointed at antenna <NUM>, feed cluster <NUM> pointed at antenna <NUM> and feed cluster <NUM> pointed at antenna <NUM>.

<FIG> illustrates an example implementation of satellite <NUM>. Satellite <NUM> includes m signal input modules 403_1 - 403_m, where an individual signal input module may include an antenna (e.g., any of the antennas illustrated in <FIG>) to receive an RF signal from a ground terminal (e.g., gateway, user terminal, or other source that is external to satellite <NUM>). Satellite <NUM> also includes n signal output modules 405_1 - 405_n, where an individual signal output module may include an antenna (e.g., any of the antennas illustrated in <FIG>) to direct an RF signal to a ground terminal (e.g., gateway, user terminal, or other recipient that is external to satellite <NUM>). The numbers of inputs m and outputs n may depend on satellite design and configuration. An amplification system <NUM> is located between the input modules and output modules to amplify received signals before sending them to a recipient. It will be understood that <FIG> is a simplified illustration and that additional components may be provided including multiplexers, demultiplexers, filters, etc. Amplification system <NUM> includes X Multi Port Amplifiers (MPA <NUM> - MPA X), where X may be any suitable number depending on satellite design.

<FIG> illustrates another implementation of satellite <NUM>. In the example of <FIG>, satellite <NUM> includes m signal input modules 403_1 - 403_m and n signal output modules 405_1 - 405_n as in the example of <FIG>. <FIG> also shows digital channelizer <NUM> located between signal input modules 403_1 - 403_m and signal output modules 405_1 - 405_n. Digital channelizer <NUM> may direct signals received at signal input modules 403_1 - 403_m and direct them to appropriate signal input modules 403_1 - 403_m so that incoming signals (e.g., from a gateway) are appropriately directed (e.g., to areas where user terminals are located). Aspects of the present technology may be implemented in a range of satellite configurations including those using analog circuits, digital circuits, or a mix of analog and digital circuits and the present technology is not limited to the examples illustrated.

<FIG> illustrates an example of an antenna <NUM> (e.g., any of the antennas described above). Antenna <NUM> includes reflector <NUM> (antenna reflector) and feed horn <NUM>. In the example illustrated in <FIG>, feed horn <NUM> transmits one or more RF signals that are reflected from reflector <NUM> and form a spot beam <NUM> that is directed towards a target area (e.g., an area of the earth's surface). In the example where antenna <NUM> receives RF signals, the arrangement of <FIG> may be reversed (e.g., an incoming spot beam from a target area is reflected from reflector <NUM> and is focused on feed horn <NUM>). Reflector <NUM> may have a suitable shape so that RF radiation is appropriately reflected. For example, reflector <NUM> may have a parabolic shape with feed horn <NUM> located at or near the focus of reflector <NUM>. Antenna <NUM> may be a fixed antenna or may be steerable (e.g., for a steerable spot beam).

<FIG> illustrates an example implementation of antenna <NUM> as a steerable antenna (e.g., as steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM><NUM>). Reflector <NUM> is attached to a satellite body <NUM> by boom <NUM> and actuator <NUM>. Feed horn <NUM> is attached to satellite body <NUM> by boom <NUM>. The position of feed horn <NUM> may be fixed with respect to satellite body <NUM> and antenna <NUM> may be steered by actuator <NUM> changing the orientation of reflector <NUM>. For example, with reflector <NUM> in a first orientation (illustrated by solid lines in <FIG>), a spot beam <NUM> is directed in a first direction (e.g., towards a first target area that) and with reflector <NUM> in a second orientation (illustrated by dotted lines in <FIG>), a redirected spot beam <NUM> is directed in a second direction (e.g., towards a second target area). Actuator <NUM> may control the orientation and/or position of reflector <NUM> to steer antenna <NUM> and allow spot beams to be directed as desired without changing the position or orientation of satellite body <NUM>.

In some cases, an antenna may include more than one feed horn fixed in a feed assembly to allow spot beams to be directed to more than one target area using the same reflector. <FIG> shows an example of antenna <NUM> that includes reflector <NUM> and feed assembly <NUM>, which includes first feed horn <NUM> and second feed horn <NUM>. First feed horn <NUM> generates first spot beam <NUM>, which may be directed to a first target area, while second feed horn <NUM> generates second spot beam <NUM>, which may be directed to a second target area. While a feed assembly containing multiple feed horns may enable multiple spot beams, these spot beams are generally not individually steerable. For example, moving a reflector that serves multiple feed horns (e.g., reflector <NUM> serving feed horns <NUM>, <NUM> of antenna <NUM>) may affect all such spot beams (e.g., spot beams <NUM> and <NUM>) so that it may not be possible to redirect an individual spot beam independently without impacting other spot beams generated by the same antenna. This may limit the utility of a steerable antenna with multiple feed horns.

<FIG> illustrates an example of antenna <NUM>, which is steerable (e.g., any of steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM><NUM> illustrated in <FIG>) without moving reflector <NUM>. For example, reflector <NUM> is attached to satellite body <NUM> by boom <NUM> in a fixed position and a fixed orientation with respect to satellite body <NUM> (e.g., without any actuator or other element that would allow reorientation or relative movement of reflector <NUM>). In non-satellite examples, boom <NUM> and boom <NUM> may be attached to other structures (e.g., to the ground, a building, an aircraft, or other object). Feed assembly <NUM> includes feed horn <NUM> and includes components to move feed horn <NUM> in order to direct a spot beam at different respective target areas. For example, <FIG> shows feed horn <NUM> in a position where it generates spot beam <NUM> (shown with solid lines). Also shown is a second position for feed horn <NUM> (in dotted lines) where it generates redirected spot beam <NUM>. Antenna <NUM> enables steering of a spot beam without moving reflector <NUM>, which may provide various benefits over arrangements that keep feed horn position fixed and move a reflector. A single feed horn may be moved as illustrated in <FIG> or more than one feed horn in a feed assembly may be individually moved as needed and the present technology is not limited to antennas having any particular number of feed horns.

In an example, reflector <NUM> is a parabolic reflector that has a focal plane and feed horn <NUM> is movable along the focal plane (or along a plane near and parallel to the focal plane) of reflector <NUM> (e.g., the range of motion of feed horn <NUM> is constrained to the focal plane of reflector <NUM>). Various mechanisms may be used to move feed horn <NUM> as illustrated. Examples of movable feed horn assemblies to move a feed horn are described below although the present technology is not limited to any particular design.

An example of a movable feed horn assembly uses a planar five bar linkage to move a feed horn along a plane. <FIG> illustrates an example of a planar five bar linkage <NUM>, which includes a first arm <NUM> (left arm) formed by a first bar <NUM> (left crank) and a second bar <NUM> (left floating link or left coupler) coupled by a first hinge <NUM> and a second arm <NUM> (right arm) formed by a third bar <NUM> (right crank) and a fourth bar <NUM> (right floating link or right coupler) coupled by a second hinge <NUM>. Second bar <NUM> and fourth bar <NUM> are connected by a third hinge <NUM>. Third hinge <NUM> may be considered an endpoint or end effector of planar five bar linkage <NUM> and may be referred to as endpoint <NUM>. In an example, a feed horn is attached at or near endpoint <NUM> (at or on one of the floating links near the endpoint of planar five bar linkage <NUM>). A fifth bar of planar five bar linkage <NUM> is formed by ground link <NUM>, which may be considered a non-moving part of planar five bar linkage <NUM> (e.g., movement of endpoint <NUM> may be relative to ground link <NUM> (base), which may be considered a stationary object for purposes of the movement of endpoint <NUM>).

First bar <NUM>, second bar <NUM>, third bar <NUM> and fourth bar <NUM> may each be formed of an elongated portion of substantially rigid material and may be of equal length or may be of unequal lengths. First hinge <NUM>, second hinge <NUM>, third hinge <NUM> may provide physical coupling of bars that allows rotation of one bar with respect to another about an axis of rotation (e.g., a pin may extend through a hinge and both bars may be rotatable about an axis of rotation that extends along a centerline of the pin). First bar <NUM> is attached to one side (left side in <FIG>) of ground link <NUM> by a first motor <NUM>, which is configured to rotate first bar <NUM> with respect to ground link <NUM>. Thus, first arm <NUM> is attached to first motor <NUM> at one end and is attached to second arm <NUM> at the other end (at endpoint <NUM>). Third bar <NUM> is attached to the other side (right side in <FIG>) of ground link <NUM> by a second motor <NUM>, which is configured to rotate third bar <NUM> with respect to ground link <NUM>. Thus, second arm <NUM> is attached to second motor <NUM> at one end and is attached to first arm <NUM> at the other end (at endpoint <NUM>). First hinge <NUM>, second hinge <NUM>, third hinge <NUM>, first motor <NUM> and second motor <NUM> may each have a respective axis of rotation (not shown) that is perpendicular to the view shown (e.g., along the z-direction, perpendicular to the x-y plane). This configuration constrains movement of the endpoint <NUM> to a plane, while enabling first motor <NUM> and second motor <NUM> to control the position of endpoint <NUM> in the plane. The range of motion of endpoint <NUM> within this plane may be limited by the dimensions of first bar <NUM>, second bar <NUM>, third bar <NUM>, fourth bar <NUM> and ground link <NUM> (e.g., by distance between first motor <NUM> and second motor <NUM>). Endpoint <NUM> may be moved from the location illustrated in <FIG> in both the x-direction and the y-direction by rotating first bar <NUM> using first motor <NUM> and rotating third bar <NUM> using second motor <NUM> to place endpoint <NUM> at a desired location.

<FIG> shows planar five bar linkage <NUM> in a second configuration that is different to the first configuration illustrated in <FIG>. Endpoint <NUM> is moved to the right (along the positive x-direction) compared with the configuration of <FIG> in this configuration. First bar <NUM> is rotated clockwise by first motor <NUM> and third bar <NUM> is rotated clockwise by second motor <NUM> to the positions illustrated to locate endpoint <NUM> as shown.

<FIG> shows planar five bar linkage <NUM> in a third configuration that is different to the first configuration illustrated in <FIG>. Endpoint <NUM> is moved to the left (along the negative x-direction) compared with the configuration of <FIG> in this configuration. First bar <NUM> is rotated counterclockwise by first motor <NUM> and third bar <NUM> is rotated counterclockwise by second motor <NUM> to the positions illustrated to locate endpoint <NUM> as shown.

<FIG> shows planar five bar linkage <NUM> in a fourth configuration that is different to the first configuration illustrated in <FIG>. Endpoint <NUM> is moved upward (along the positive y-direction) compared with the configuration of <FIG> in this configuration. First bar <NUM> is rotated clockwise by first motor <NUM> and third bar <NUM> is rotated counterclockwise by second motor <NUM> as illustrated to locate endpoint <NUM> as shown (more distant from ground link <NUM> than in <FIG>).

<FIG> shows planar five bar linkage <NUM> in a fifth configuration that is different to the first configuration illustrated in <FIG>. Endpoint <NUM> is moved downward (along the negative y-direction) compared with the configuration of <FIG> in this configuration. First bar <NUM> is rotated counterclockwise by first motor <NUM> and third bar <NUM> is rotated clockwise by second motor <NUM> as illustrated to locate endpoint <NUM> as shown (closer to ground link <NUM> than in <FIG>).

The angles of first bar <NUM> and third bar <NUM> with respect to ground link <NUM> may be controlled by first motor <NUM> and second motor <NUM> in order to position endpoint <NUM> at a desired location (e.g., desired x and y coordinates) as illustrated by the examples of <FIG> (e.g., movement along x-direction illustrated in <FIG> and movement along y-direction illustrated in <FIG>). For example, first motor <NUM> and second motor <NUM> may be stepper motors that may be rotated a predetermined number of steps in response to a command in order to position endpoint <NUM> at a predetermined position that is a function of the numbers of steps. Alternatively, first motor <NUM> and second motor <NUM> may be servo motors or stepper motors or other rotary motors that may be controlled to control position of endpoint <NUM>.

Examples of the present technology include a feed horn (e.g., feed horn <NUM>) attached at or near an endpoint of a planar five bar linkage (e.g., endpoint <NUM> of planar five bar linkage <NUM>) so that the position of the feed horn within a plane may be changed in response to a command (e.g., while a satellite that includes the feed horn is in space) as illustrated by the examples of <FIG>.

<FIG> shows a first example of feed horn <NUM> attached to planar five bar linkage <NUM>. In the example of <FIG>, feed horn <NUM> is centered over third hinge (endpoint) <NUM> and may be attached to a pin (not shown) of third hinge <NUM> that forms the axis of rotation about which second bar <NUM> and fourth bar <NUM> rotate. For example, feed horn <NUM> may be located above third hinge <NUM> (in the positive z-direction, perpendicular to the x-y plane of <FIG>). Feed horn <NUM> is concentric with third hinge <NUM> and may be free to rotate with respect to both second bar <NUM> and fourth bar <NUM> in this configuration.

<FIG> shows a perspective view of feed horn <NUM> attached to planar five bar linkage <NUM> corresponding to the plan view of <FIG>. Axis of rotation <NUM> of first motor <NUM>, axis of rotation <NUM> of second motor <NUM>, axis of rotation <NUM> of first hinge <NUM>, axis of rotation <NUM> of second hinge <NUM> and axis of rotation <NUM> of third hinge <NUM> are shown extending in parallel along the z-direction so that rotation of these components is constrained to the x-y plane (the x-y plane illustrated may coincide with the focal plane of a reflector so that feed horn <NUM> is constrained to movement in the focal plane of a corresponding reflector). Feed horn <NUM> is shown as a cylindrical component that has axis of rotation <NUM> of third hinge <NUM> extending through its center. A flexible RF conduit <NUM> (e.g., a flexible wave guide or a coaxial cable) extends from feed horn <NUM> and may couple feed horn <NUM> to communication circuits (e.g., to a transmitter or receiver). First motor <NUM> and second motor <NUM> may be attached to any suitable structure (not shown) so that the distance between them (length of ground link <NUM>) is constant. The combination of a feed horn (e.g., feed horn <NUM>), a linkage to enable movement of a feed horn along a plane (e.g., planar five bar linkage <NUM>) and first and second motors attached to the linkage to move the feed horn along the plane (e.g., first motor <NUM> and second motor <NUM>) may be considered a movable feed horn assembly that may be used to move a feed horn in an antenna (e.g., move feed horn <NUM> in feed assembly <NUM>).

<FIG> shows an alternative example of attachment of feed horn <NUM> and planar five bar linkage <NUM>. In <FIG>, feed horn <NUM> and fourth bar <NUM> are fixedly attached and are not rotatable with respect to each other. The combination of feed horn <NUM> and fourth bar <NUM> is rotatable with respect to second bar <NUM> through third hinge <NUM>. Thus, from a mechanical perspective, feed horn <NUM> may be considered a part of fourth bar <NUM> in this example.

<FIG> shows another alternative example of attachment of feed horn <NUM> and planar five bar linkage <NUM>. Like the example of <FIG>, feed horn <NUM> and fourth bar <NUM> are fixedly attached and are not rotatable with respect to each other and the combination of feed horn and fourth bar <NUM> are rotatable with respect to second bar <NUM> through third hinge <NUM>. Unlike the example of <FIG> (and <FIG>), feed horn <NUM> is not centered over third hinge <NUM> and instead is near third hinge <NUM>. In <FIG>, feed horn <NUM> is offset from third hinge <NUM> (e.g., axis of rotation <NUM> of third hinge <NUM> is offset from the center of feed horn <NUM>). The combination of a feed horn, linkage, and motors (e.g., feed horn <NUM>, planar five bar linkage <NUM>, first motor <NUM> and second motor <NUM> as shown in <FIG>) may be considered an example of a movable feed horn assembly. While the examples of <FIG> show different configurations of feed horn <NUM> with respect to planar five bar linkage <NUM> (located at or near third hinge <NUM>), the present technology is not limited to any particular example shown. While the examples of <FIG> and <FIG> use first motor <NUM> and second motor <NUM> as rotational actuators to rotate first bar <NUM> and third bar <NUM>, any suitable rotating actuator may be used. For example, a tortional spring and a remote cable may be used as a rotational actuator. In other examples, a pneumatic actuator or hydraulic actuator may be used, or an actuator may include a combination of actuating elements (e.g., electromechanical, mechanical, pneumatic, hydraulic and/or other elements).

In some examples (e.g., as illustrated in <FIG>), a feed assembly (e.g., feed assembly <NUM>) of an antenna (e.g., antenna <NUM>) may include a single movable feed horn assembly (e.g., as illustrated in examples of <FIG>) to allow the direction of a spot beam to be changed (e.g., while keeping a reflector stationary). In other examples, more than one movable feed horn assembly may be provided in an antenna so that directions of more than more than one spot beam can be independently changed.

<FIG> shows an example of an antenna <NUM>, which includes reflector <NUM> that is fixedly attached to satellite body <NUM> by boom <NUM>. Antenna <NUM> includes feed assembly <NUM> attached to satellite body <NUM> by boom <NUM>. Feed assembly <NUM> includes two movable feed horn assemblies: movable feed horn assembly <NUM>, which includes feed horn <NUM> and movable feed horn assembly <NUM>, which includes feed horn <NUM>. Each movable feed horn assembly may include a linkage (e.g., planar five bar linkage <NUM>) and motors (e.g., first and second motors <NUM>, <NUM>) to move a feed horn (e.g., feed horn <NUM>, <NUM>) along a common plane (e.g., along focal plane of reflector <NUM>). Spot beam <NUM> is movable by moving corresponding feed horn <NUM> as previously described with respect to <FIG>. In addition, spot beam <NUM> is movable by moving feed horn <NUM> of movable feed horn assembly <NUM>. While feed assembly <NUM> is shown having two movable feed horn assemblies to enable two independently steerable spot beams, other examples of feed assemblies may include three or more movable feed horn assemblies to enable three or more independently steerable spot beams using a common reflector (e.g., reflector <NUM>).

<FIG> shows an example of a feed assembly <NUM> that includes a hub <NUM> and three movable feed horn assemblies <NUM>, <NUM>, <NUM> attached to hub <NUM>. Each movable feed horn assembly includes a respective feed horn and a linkage and motors to move it (e.g., as described in any example above). For example, movable feed horn assembly <NUM> includes feed horn <NUM>, movable feed horn assembly <NUM> includes feed horn <NUM> and movable feed horn assembly <NUM> includes feed horn <NUM>. Feed horns <NUM>, <NUM> and <NUM> are each independently movable along the x-y plane (a common plane, which may be at or near the focal plane of a corresponding reflector) by their respective movable feed horn assemblies so that corresponding spot beams can be independently redirected. Feed assembly <NUM> also includes feed horn <NUM>, which is attached to hub <NUM> by a fixed attachment and cannot be moved with respect to hub <NUM> so that a corresponding spot beam may not be redirected without moving a corresponding reflector or satellite body. Thus, feed assembly <NUM> includes both stationary and movable feed horns.

<FIG> shows feed assembly <NUM> in a different configuration to that shown in <FIG> after feed horns <NUM>, <NUM> and <NUM> are independently moved in the directions indicated by respective arrows. For example, feed horn <NUM> is moved inward toward hub <NUM>, feed horn <NUM> is moved outward away from hub <NUM> and feed horn <NUM> is moved clockwise about hub <NUM>. Corresponding spot beams may be redirected accordingly. Feed horn <NUM> remains at the location shown in <FIG> and a corresponding spot beam may remain as before (if a corresponding reflector and satellite body remain as before). The present technology allows one or more spot beams to be steered (redirected) independently of other spot beams associated with the same antenna, without moving a reflector of the antenna or a satellite body to which the antenna is attached. This may allow a single antenna to redirect multiple spot beams so that each spot beam does not require a dedicated steerable antenna. This may allow a reduction in the number of antennas used. For example, two or more of <NUM> degree steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may be replaced by an antenna having two or more movable feed horn assemblies and two or more of <NUM> degree steerable antennas <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may be replaced by an antenna having two or more movable feed horn assemblies.

<FIG> shows a perspective view of feed assembly <NUM> corresponding to the plan view of <FIG>. <FIG> shows feed horns <NUM>, <NUM>, <NUM> and <NUM> attached to hub <NUM> so that feed horns <NUM>, <NUM>, <NUM> are movable with respect to hub <NUM> (along a plane) while feed horn <NUM> remains stationary.

<FIG> illustrate examples in which movable feed horn assemblies <NUM>, <NUM>, <NUM> provide non-overlapping ranges of movement for their respective feed horns <NUM>, <NUM>, <NUM>. These ranges of movement may correspond to spot beam ranges that allow each corresponding spot beam to be redirected to a target area within a respective range. For example, movable feed horn assembly <NUM> may have a range of movement that corresponds to target areas in north America while movable feed horn assembly <NUM> may have a range of movement that corresponds to target areas in Europe. While movable feed horn assembly <NUM> may be movable to redirect a corresponding spot beam from a target area in Maine to a target area in Oregon, it may not be able to redirect it to a target area in Portugal. Similarly, while movable feed horn assembly <NUM> may be movable to redirect a corresponding spot beam from a target area in Denmark to a target area in Portugal, it may not be possible to redirect it to a target area in Maine. Positions and ranges of movement of each movable feed horn assembly may be customized according to the geographic region within which it is desirable to be able to redirect a corresponding spot beam. Ranges of movement may be increased, for example, by using longer arms for some movable feed horn assemblies. In some cases, where a simple range of motion (e.g., along a line) is adequate, a simpler linkage may be used (e.g., a four bar linkage). In some cases, movable feed horn assemblies may provide overlapping ranges for respective feed horns. This may provide some redundancy (e.g., if a feed horn fails, a neighboring feed horn may be relocated to the position of the failed feed horn to replace it).

<FIG> is a schematic illustration that includes movable feed horn assemblies <NUM>, <NUM>, <NUM> of feed assembly <NUM> and control circuit <NUM>, which is connected to movable feed horn assemblies <NUM>, <NUM>, <NUM> to control movement of feed horns <NUM>, <NUM>, <NUM>. Control circuit <NUM> is connected to communication circuit <NUM>, which may be in communication with a network control center (e.g., NCC <NUM>) to enable commands from the network control center to be sent to control circuit <NUM>. In an example, control circuit <NUM> and/or communication circuit <NUM> are implemented by payload communication circuit <NUM> and/or TC&R communication circuit <NUM>. For example, a command may be received to redirect one or more spot beam associated with one or more of feed horns <NUM>, <NUM>, <NUM> from a first target area to a second target area. Control circuit <NUM> may receive such a command from communication circuit <NUM> and may determine which of feed horns <NUM>, <NUM>, <NUM> should be moved and how it should be moved. For example, control circuit <NUM> may convert a movement indicated by a command into numbers of steps for first and second motors of a specified movable feed horn assembly to rotate in order to redirect a corresponding spot beam as indicated. Thus, control circuit <NUM> may translate instructions to redirect a spot beam into a specified number of steps for stepper motors and may send corresponding signals to the specified stepper motors. For example, in order to move feed horn <NUM> to a new location corresponding to redirecting a corresponding spot beam, control circuit <NUM> may command a first motor of movable feed horn assembly <NUM> to rotate a first number of steps and command a second motor of movable feed horn assembly <NUM> to rotate a second number of steps. Feed horns <NUM> and <NUM> (and any stationary feed horns) are not affected by such movement.

For purposes of this document, it should be noted that the dimensions of the various features depicted in the figures may not necessarily be drawn to scale.

For purposes of this document, reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "another embodiment" may be used to describe different embodiments or the same embodiment.

For purposes of this document, a connection may be a direct connection or an indirect connection (e.g., via one or more other parts). In some cases, when an element is referred to as being connected or coupled to another element, the element may be directly connected to the other element or indirectly connected to the other element via intervening elements. When an element is referred to as being directly connected to another element, then there are no intervening elements between the element and the other element. Two devices are "in communication" if they are directly or indirectly connected so that they can communicate electronic signals between them.

For purposes of this document, the term "based on" may be read as "based at least in part on.

For purposes of this document, without additional context, use of numerical terms such as a "first" object, a "second" object, and a "third" object may not imply an ordering of objects but may instead be used for identification purposes to identify different objects.

For purposes of this document, the term "set" of objects may refer to a "set" of one or more of the objects.

Claim 1:
An apparatus comprising:
a planar five bar linkage (<NUM>) having a ground link (<NUM>) and an endpoint (<NUM>);
a feed horn attached (<NUM>) at or near the endpoint (<NUM>) of the planar five bar linkage (<NUM>);
a first motor (<NUM>) attached to a first side of the ground link (<NUM>) to move the endpoint (<NUM>); and
a second motor (<NUM>) attached to a second side of the ground link (<NUM>) to move the endpoint (<NUM>);
wherein the planar five bar linkage (<NUM>) includes a first bar (<NUM>) extending from the first motor (<NUM>), a second bar (<NUM>) extending between the first bar (<NUM>) and the endpoint (<NUM>), a third bar (<NUM>) extending from the second motor (<NUM>) and a fourth bar (<NUM>) extending between the third bar (<NUM>) and the endpoint (<NUM>);
wherein the first bar (<NUM>) is coupled to the second bar (<NUM>) by a first hinge (<NUM>), the third bar (<NUM>) is coupled to the fourth bar (<NUM>) by a second hinge (<NUM>) and the second bar (<NUM>) is coupled to the fourth bar (<NUM>) by a third hinge (<NUM>); and
wherein the first motor (<NUM>), the second motor (<NUM>), the first hinge (<NUM>), the second hinge (<NUM>) and the third hinge (<NUM>) each has a respective axis of rotation that is perpendicular to a plane to enable movement of the endpoint (<NUM>) along the plane.