Patent Description:
Small satellites have limited space to store electronics and an antenna, which becomes technically challenging when the electronics and antenna are designed to operate at the lower L-band and S-band frequencies. High performance antenna operating at those frequencies usually require significant volume. Even antennas designed to operate at the higher frequencies up to and above <NUM> have size constraints that make them difficult to implement into small satellites, even though antennas at those upper frequencies are usually reduced in size. This problem becomes challenging when small satellites are built as CubeSat platforms, which are miniaturized satellites made up of multiple block units known as CubeSats, each block unit being about <NUM> by <NUM> by <NUM> inches. CubeSats are advantageous for smaller satellites because they are designed to use commercial off-the-shelf (COTS) components for their major circuits and can be implemented for custom satellite operations.

In most practical small satellite applications, a number of CubeSat units are combined together to form a CubeSat platform as a small satellite that is typically intended for Low Earth Orbit (LEO) and perform scientific research and explore new space technologies. CubeSats are advantageous because their use as block units to build small satellites shortens the satellite development cycle, permits greater diversity in satellite design since each small satellite can be designed for a specific function, and reduces the overall cost of satellite deployment. CubeSats and even larger classes of small satellites often are suitable for launch with multiple small satellites per payload, thus using the excess capacity of larger launch vehicles and reducing the risk to the rest of the launch vehicle and other payloads.

Typical CubeSat satellite platforms are formed from multiple, individual CubeSat block units combined together and include a 6U design of about <NUM> x <NUM> x <NUM> inches or a 12U design of about <NUM> x <NUM> x <NUM> inches. Additionally, the small satellite class also envelopes larger form factors, such as EELV Secondary Payload Adapter (ESPA) each forming a satellite in the <NUM> to about <NUM> class. Small satellites can be propelled by cold gas, chemical promotion, electric propulsion, or solar sails. Most CubeSats and similar small satellites have internal batteries for power, which preferably include solar cells.

Many Low Earth Orbit (LEO) small satellites require an antenna for communicating in the L-band and S-band, and also X-band and Ka-band can be used for higher data rate communications. These higher frequency bands allow the use of smaller antennae due to the higher frequencies, but the constraints of small satellites, such as CubeSats, still make it difficult to implement workable antennas, even at the higher frequencies. These small satellites have limited volume and designing an antenna that can be compactly stored and deployed once orbit is reached is a challenge.

For example, horn antennas are often used on larger satellites, but take up a relatively large volume, especially at the lower L-band and S-band frequencies, and are challenging to fit onto smaller satellites. Wideband antennas and communication modems offer the valuable potential to communicate with various ground stations or even perhaps other satellites directly.

A log periodic parasitic monopole antenna (LPPMA), for example, operates as a high performance antenna and may be used in demanding satellite communication applications since it has wideband performance, multi-polarization, and excellent directivity. A technical drawback of this antenna, however, is its large volume, making it difficult to implement in small satellites. For example, a log periodic parasitic monopole antenna may have a wide <NUM>:<NUM> bandwidth and operate up to <NUM> and provide six arms for multi-polarization in both transmit and receive applications, making that antenna advantageous, but difficult to implement in CubeSat applications. A multi-arm sinuous antenna has similar benefits, but again, it is difficult to implement that antenna in small satellites since the antenna requires a relatively large volume compared to the size of the satellite. A horn antenna is another popular satellite antenna since it can operate alone or as a feed antenna and have good directivity, low standing wave ratio (SWR), broad bandwidth and inexpensive construction and adjustment. However, a horn antenna should have a minimum size relative to the wavelength of the incoming or outgoing signal, and thus, the horn must be relatively large, again making a horn antenna difficult to implement on a small satellite. As a result, deployment of most antennas, including a horn antenna, is difficult on small satellites, especially those manufactured as CubeSats.

Prior art can be found in <CIT> which generally relates to a horn antenna.

In general, an outer space deployable antenna may include a waveguide antenna feed section. A first plurality of wires and a first plurality of biased hinges may couple the first plurality of wires together to be self-biased to move between a collapsed stored configuration and an extended deployed configuration. A horn antenna section may be coupled to the waveguide antenna feed section and may comprise a second plurality of wires and a second plurality of biased hinges coupling the second plurality of wires together to be self-biased to move between the collapsed stored configuration and the extended deployed configuration. A flexible electrically conductive layer may cover the waveguide antenna feed section and the horn antenna section in at least the extended deployed configuration.

The waveguide antenna feed section may have a rectangular cross section in the extended deployed configuration. The waveguide antenna feed section may have a square cross section in the extended deployed configuration. The horn antenna section may have an inverted pyramidal cross section in the extended deployed configuration.

In some embodiments, the first plurality of wires may comprise a first pair of wires, each first pair of wires comprising lower and upper wires with a corresponding hinge therebetween. The second plurality of wires may comprise a second pair of wires, each second pair of wires comprising lower and upper wires with a corresponding hinge therebetween. The flexible electrically conductive layer may be coupled to the waveguide antenna feed section and the horn antenna section only at selected attachment points. The flexible electrically conductive layer may comprise a flexible dielectric layer and a metallization layer thereon.

In yet another embodiment, a satellite may include a satellite housing and a satellite transceiver carried by the satellite housing. An outer space deployable antenna may be carried by the satellite housing and may be coupled to the satellite transceiver. The outer space deployable antenna may comprise a waveguide antenna feed section that may comprise a first plurality of wires and a first plurality of biased hinges coupling the first plurality of wires together to be self-biased to move between a collapsed stored configuration and an extended deployed configuration. A horn antenna section may be coupled to the waveguide antenna feed section and may comprise a second plurality of wires and a second plurality of biased hinges coupling the second plurality of wires together to be self-biased to move between the collapsed stored configuration and the extended deployed configuration. A flexible electrically conductive layer may cover the waveguide antenna feed section and the horn antenna section in at least the extended deployed configuration.

In an example, the flexible electrically conductive layer may include etched patterns to interact and direct electromagnetic energy. The flexible electrically conductive layer may include electronic components.

Another aspect is directed to a method for making an outer space deployable antenna. The method includes assembling a waveguide antenna feed section that may comprise a first plurality of wires and a first plurality of biased hinges coupling the first plurality of wires together to be self-biased to move between a collapsed stored configuration and an extended deployed configuration. The method also includes assembling a horn antenna section coupled to the waveguide antenna feed section and comprising a second plurality of wires and a second plurality of biased hinges coupling the second plurality of wires together to be self-biased to move between the collapsed stored configuration and the extended deployed configuration. The method may further include covering the waveguide antenna feed section and the horn antenna section with a flexible electrically conductive layer.

The present description is made with reference to the accompanying drawings, in which exemplary embodiments are shown. However, many different embodiments may be used, and thus, the description should not be construed as limited to the particular embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in different embodiments.

Referring initially to <FIG>, a satellite is illustrated generally at <NUM> and shown orbiting Earth (E) in a Low Earth Orbit (LEO) as typical for small satellites, although other satellite orbit altitudes may be established depending on satellite functions and design. The satellite <NUM> includes a satellite housing <NUM> shown in partial cut away and a satellite transceiver <NUM> carried by the satellite housing <NUM> and solar panels <NUM>. The satellite transceiver <NUM> and any associated electronic components and circuits may be formed from conventional Off-The-Shelf (OTS) components as is typical for those smaller satellites formed as CubeSats.

An outer space deployable antenna is indicated generally at <NUM> and formed as a horn antenna and carried by the satellite housing <NUM> and coupled to the satellite transceiver <NUM>. Basic components of the outer space deployable antenna <NUM> are better illustrated in <FIG>, and in a second embodiment of <FIG>, and include a waveguide antenna feed section <NUM> that includes a first plurality of wires <NUM> and a first plurality of biased hinges <NUM> coupling the first plurality of wires together to be self-biased to move between the collapsed stored configuration and extended deployed configuration.

A horn antenna section <NUM> is coupled to the waveguide antenna feed section <NUM> and includes a second plurality of wires <NUM> and a second plurality of biased hinges <NUM> coupling the second plurality of wires together to be self-biased to move between the collapsed stored configuration and the extended deployed configuration. A flexible electrically conductive layer <NUM> covers the waveguide antenna feed section <NUM> and the horn antenna section <NUM> in at least the extended deployed configuration. The plurality of wires <NUM>,<NUM> and biased hinges <NUM>,<NUM> for both the waveguide antenna feed section <NUM> and horn antenna section <NUM> provide a wire framework allowing the outer space deployable antenna <NUM> to be stowed flat as shown in <FIG>, and extended into a deployed configuration through a series of progressively expanded or extended positions as shown in <FIG> and fully expanded into the extended deployed configuration (<FIG>). The extended and deployed antenna <NUM> operates as a horn antenna on a small satellite <NUM> such as the CubeSat. The waveguide antenna feed section <NUM> may have a square cross-section in the extended deployed configuration as shown in <FIG> and <FIG>, or a rectangular cross-section as shown in the embodiment of the antenna <NUM>' <FIG>, where prime notation is used for corresponding similar components as in the embodiment of <FIG> and <FIG>. The horn antenna section <NUM> has an inverted pyramidal cross-section in its extended deployed configuration.

This first plurality of wires <NUM> include a first pair of wires with each first pair of wires including lower and upper wires shown respectively at 34a and 34b, with the corresponding biased hinge <NUM> therebetween. The second plurality of wires <NUM> also include a second pair of wires with each second pair of wires including lower and upper wires shown respectively at 42a and 42b with the corresponding hinge <NUM> therebetween.

To allow the flexible electrically conductive layer <NUM> to expand with the waveguide antenna feed section <NUM> and horn antenna section <NUM>, the layer is substantially free-floating and moves without binding to the plurality of wires <NUM>,<NUM>. The flexible electrically conductive layer <NUM> may be coupled to the waveguide antenna feed section <NUM> and the horn antenna section <NUM> at selected attachment points, such that as the first and second plurality of wires <NUM>,<NUM> are deployed upward, the flexible electrically conductive layer <NUM> may slide relative to the wires <NUM>,<NUM> as they are deployed upward. The flexible electrically conductive layer <NUM> is connected to the wires <NUM>,<NUM> such that when expanded into the fully deployed position, the conductive layer is drawn tight.

In one embodiment, the flexible electrically conductive layer <NUM> is shown in the enlarged sidewall section in <FIG>, and includes a flexible dielectric layer <NUM> and a metallization layer <NUM>. The flexible electrically conductive layer <NUM> may be formed from metallized Mylar as a flexible thin material that could range from a low <NUM> or <NUM> mil thickness to substantially greater thicknesses, such as up to <NUM> to <NUM> mil thickness for added rigidity. Mylar has been found advantageous as a metallized BoPET (Biaxially-Oriented Polyethylene Terephthalate) since it has good tensile strength, chemical and dimensional stability, good barrier resistance and insulator properties, and excellent reflectivity. The metallization layer in an example could be about <NUM>/<NUM> mil thick in an example and be formed as a copper coating. It is also possible to use Kapton as a polyimide film that includes a metallized layer thereon.

The advantage of using metallized Mylar or Kapton with the copper coating as a preferred metallic coating is it is possible to etch circuitry <NUM> or patterns (<FIG>) onto the side of the antenna <NUM>, such as Low Noise Amplifiers (LNA) or other active or passive electronic devices. In this example, the etched circuitry <NUM> or patterns is connected to a signal junction and feed element <NUM> as part of the waveguide antenna feed section <NUM>. Any etched circuitry <NUM> could be powered by a <NUM> or <NUM> volt DC voltage as typical in satellites with power provided by solar powered cells. An active RF feed could be provided with etched components. Any heat generated by active components formed or positioned on the antenna <NUM> may be minimized since the satellite housing <NUM> may provide some cooling, together with the antenna <NUM> itself as a thermal radiator in outer space. The first plurality of wires <NUM> and second plurality of wires <NUM> may be formed from rigid small gauged wire ranging from a thick <NUM> gauge to <NUM> gauge. Other sizes could be used depending on the design parameters. In an example, etched metallization circuitry <NUM> or patterns may be included on one or more conductive layers, including circuitry or patterns which may interact with or direct electromagnetic fields or energy either independently or together with embedded attached electronic circuitry. The etched circuitry <NUM> or patterns may form electronic components that are attached to the deployed, flexible electrically conductive layer <NUM>.

Different materials could be used to form the wires <NUM>,<NUM>, including reinforced carbon fiber, reinforced nylon filaments, carbon fiber reinforced aluminum-magnesium alloy composite, a lightweight metallic material, such as aluminum or lightweight high tensile steel wire, or other components that impart rigidity to the wires. The biased hinges <NUM>,<NUM> coupling the wires <NUM>,<NUM> together may use coupling pins connected to flattened portions of the wire having holes receiving the pins and springs connected to the pins and wires, or the wires could be connected directly to springs that help form the biased hinges. Examples of different springs that could connect directly to wires <NUM>,<NUM> and act as pivots or connect to coupling pins and include a hairpin spring, s <NUM>° deflector spring, a Gardener spring, a torsion spring, a constant force spring, or a coil spring. A scissor strut assembly formed of wires with biased springs may be used.

In an example, a solar panel <NUM> carried by the satellite housing <NUM> could retain the outer space deployable antenna <NUM> when it is stowed in its collapsed stored configuration. For example, a small storage area could be formed in the side of the satellite <NUM> forming a slight indentation in the housing <NUM>. The antenna <NUM> may be retained in the collapsed stored configuration and covered and retained by the solar panels <NUM> that keep it from extending outward. When the satellite <NUM> reaches its desired orbit, the solar panels <NUM> move outward away from the satellite via a normal pivot mechanism commonly used in small satellites, and the biased hinges <NUM>,<NUM> coupling the first and second plurality of wires <NUM>,<NUM> together will be free to deploy outward since the solar panel covering the collapsed and stored antenna <NUM> has been removed, allowing the antenna <NUM> to extend into its deployed configuration. Other mechanisms besides the solar panels <NUM> to retain the antenna <NUM> in a collapsed configuration may include a lock mechanism connected to each spring forming biased hinges <NUM>,<NUM>. When the satellite <NUM> reaches a desired orbit, a pivoting latch could be released, allowing any springs to bias the wires <NUM>,<NUM>, permitting the waveguide antenna feed section <NUM> and horn antenna section <NUM> to extend into the deployed configuration. It is possible to use other mechanisms, including extending rods or a radial deployment mechanism, where the antenna <NUM> is stowed flat on its side and springs can bias the antenna radially upward from the side.

The outer space deployable antenna <NUM> as described provides various advantages for use with small satellites such as CubeSats. The antenna <NUM> is formed as a lightweight antenna that has low volume and high power handling capability. It can be single or dual polarization and may have a simple mechanism for deployment. Various shapes could be selected for the antenna <NUM> besides the illustrated square (<FIG>) or rectangular (<FIG>) waveguide antenna feed section <NUM>,<NUM>' and the inverted pyramidal cross-section for the horn antenna section <NUM>. Cylindrical or other known horn antenna shapes sometimes employed as satellite antennas could be used. The smooth side walls formed by the flexibly electrically conductive layer <NUM> when the antenna is in its extended deployed configuration provides a smooth side wall for low signal loss. Use of the flexible dielectric layer <NUM> having the metallization layer <NUM> such as metallized Mylar permits etched circuit patterns to be formed on the side walls. This outer space deployable antenna <NUM> has a high compaction ratio. It is possible to use the antenna <NUM> with other reflector antennas for a wide range of applications from <NUM> to <NUM>, and it can also be used by itself without a reflector.

The antenna may be used with remote sensing similar to a Hawkeye <NUM> system for RF sensing and used in different communications with different scenarios, including voice communication, machine-to-machine communication, and special communications. The antenna <NUM> may be adapted for a high power transmit broadcast application with PNT, paging, beacons, and similar applications.

Different manufacturing techniques may be used and an example is shown in the high-level flowchart of <FIG>. A method for making the outer space deployable antenna <NUM> is illustrated generally at <NUM>. The process starts (Block <NUM>) and the waveguide antenna feed section is assembled (Block <NUM>) by connecting the first plurality of wires together to be self-biased such as by a spring mechanism that is incorporated into the connection. The horn antenna section is assembled (Block <NUM>) by connecting the second plurality of wires together, including any springs and hinge mechanism. The waveguide antenna feed section is connected to the horn antenna section by connecting the first plurality of wires to the second plurality of wires to form a hinged connection (Block <NUM>). The waveguide antenna feed section and the horn antenna section are covered with the flexible electrically conductive layer at selected points (Block <NUM>). The process ends (Block <NUM>).

Claim 1:
A method (<NUM>) for making a deployable antenna comprising: assembling (<NUM>) a waveguide antenna feed section comprising a first plurality of wires and a first plurality of biased hinges coupling the first plurality of wires together to be self-biased to move between a collapsed stored configuration and an extended deployed configuration; and assembling (<NUM>) a horn antenna section coupled to the waveguide antenna feed section and comprising a second plurality of wires and a second plurality of biased hinges coupling the second plurality of wires together to be self-biased to move between the collapsed stored configuration and the extended deployed configuration.