Patent Application
20240204415
The present invention relates to the field of antennas, and, more particularly, to an antenna having a flexible antenna reflector layer supported by antenna ribs that are movable between deployed and partially stowed positions and related methods.
An antenna that is configured to be mounted to a space vehicle, such as a satellite, usually includes a number of antenna ribs that support a flexible antenna reflector layer, such as a conductive mesh. The antenna is initially stowed, and when in orbit, the antenna is deployed from its stowed position. To ensure that the antenna is deployed in orbit without snagging and binding, great care is taken when initially stowing the antenna. These antennas usually include cords and ties that interconnect the flexible antenna reflector layer to the rigid antenna ribs and ensure that when the antenna is deployed, the proper antenna curvature, such as a parabolic configuration, is maintained. The antenna cords and ties are configured to ensure there is no snagging or binding when the antenna is deployed and ensure sufficient tension is imparted to the flexible antenna reflector layer to maintain not only the desired antenna configuration, but also maintain adequate antenna performance.
Many of these antenna unfortunately are not configured for stowing in orbit. Even a partial, in-orbit stow increases the chances that the antenna ties, cords, or reflector layer may entangle during redeployment. For example, if the antenna is partially stowed in orbit, and then redeployed, often one or more of the cords, ties or flexible antenna reflector layer may bind or “snag,” making redeployment challenging. Even after redeployment, if only a small segment of the flexible antenna reflector layer is folded or snagged, that segment can create undesirable antenna performance, and may sometimes even render the antenna inoperable. There are therefore advantages in configuring an antenna that may be fully deployed, and later partially or fully stowed in orbit, and then successfully deployed again without bunching, entangling or snagging the ties, cords or flexible antenna reflector layer.
In general, an antenna may comprise a plurality of rigid antenna ribs, adjacent antenna ribs being relatively moveable between first and second positions, and a flexible antenna reflector layer. A flexible support member may extend behind the flexible antenna reflector layer between adjacent antenna ribs, the flexible support strip having first and second sets of openings therein. A drawstring may extend through the first set of openings in the flexible support member between adjacent ribs. A rear support cord may be behind the flexible support member between adjacent ribs. A plurality of tie cords may end between the flexible antenna reflector layer and the rear support cord and may pass through respective ones of the second set of openings in the flexible support member. A biasing member may maintain tension in the drawstring as adjacent antenna ribs move between the first and second positions so that the flexible support member defines a pleated support body for the flexible antenna reflector layer.
The adjacent antenna ribs may be movable to a fully stowed position. The first position may comprise a deployed position and the second position may comprise a partially stowed position. The first and second sets of openings may be arranged in an alternating pattern along the flexible support member. The flexible support member may comprise a flexible strip. The biasing member may comprise a constant force spring, for example.
The flexible antenna reflector layer may comprise a conductive mesh. The plurality of antenna ribs and flexible antenna reflector surface layer may define a parabolic antenna reflector surface. An antenna hub may pivotally mount the plurality of antenna ribs. An antenna feed may be associated with the flexible antenna reflector layer. The plurality of antenna ribs may be configured to be mounted to a space vehicle.
Another aspect is directed to a method for making an antenna. The method includes coupling a flexible support member extending behind a flexible antenna reflector layer between adjacent antenna ribs, the flexible support strip having first and second sets of openings therein and adjacent antenna ribs being relatively moveable between first and second positions. The method also includes coupling a drawstring extending through the first set of openings in the flexible support member between adjacent ribs and coupling a plurality of tie cords ending between the flexible antenna reflector layer and a rear support cord and passing through respective ones of the second set of openings in the flexible support member.
The method also includes coupling a biasing member for maintaining tension in the drawstring as adjacent antenna ribs move between the first and second positions so that the flexible support member defines a pleated support body for the flexible antenna reflector layer.
Other objects, features and advantages of the present embodiments will become apparent from the detailed description which follows, when considered in light of the accompanying drawings in which:
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.
Referring now to
A flexible antenna reflector layer 38, such as formed from a conductive mesh, is carried by the rigid antenna ribs 22, and in this example shown in
A flexible support member 42 formed as a flexible strip may extend behind the flexible antenna reflector layer 38 between adjacent antenna ribs 22 as best shown in
A plurality of tie cords 54 extend and end between the flexible antenna reflector layer 38 and the rear support cord 52 and pass through respective ones of the second set of openings 46 in the flexible support member 42 (
The flexible antenna reflector layer 38 (the conductive mesh) is pleated by the flexible strip 42 as the adjacent antenna ribs 22 are moved into the second position 32 corresponding to the partially stowed position as shown in
The kinematic movement of the rigid antenna ribs 22 while stowing in orbit may disrupt the curvature and tension of the flexible antenna reflector layer 38. The flexible strip 42 may introduce a new parabolic shape. The flexible strip 42 may be formed of a material to impart the parabolic shape and have some material memory. The flexible strip 42 also may have different amplitudes between the crest and trough and may be dependent upon the distance between the flexible antenna reflector layer as the conductive mesh 38 and the rear support cords 52. The flexible support member 42 in the example of
The drawstring 50 extends through the first set of openings 44 in the flexible support member 42 between adjacent antenna ribs 22. The drawstring 50 cooperates with the plurality of tie cords 54 that extend and end between the flexible antenna reflector layer 38 and rear support cord 52 and passes through respective ones of the second set of openings 46 in the flexible support member 42. As the drawstring 50 is held constantly taut by the biasing member 58, the distance between where the drawstring 50 enters and exits the flexible strip 42 develops a unique “pleating” result that occurs naturally to match the excess length of the rear support cord 52 and flexible antenna reflector layer 38 as a conductive mesh that is managed during partial stowing of the antenna 20 in orbit.
In the example of the antenna 20 shown in
The length of the flexible strip 42, the number of periods, amplitudes, and tie cord 54 spacing (
As noted before, the biasing member 58 may be formed as a constant force spring and maintains the tension in the drawstring 50 as adjacent antenna ribs 22 move between the first and second positions 30,32 so that the flexible support member as the flexible strip 42 defines a pleated support body for the flexible antenna reflector layer 38. In the example of the schematic diagram of the biasing member 58 of
Each drawstring 50 includes an associated biasing member 58 connected to the drawstring 50 (
The antenna 20 achieves a “hands-off,” in orbit stow and deploy process. The flexible antenna reflector layer as a conductive mesh 38 in an example may be pleated successfully without tangling, and the rear support cords 52 and tie cords 54 successfully managed not only during stowing of as much as 70%-90% of the antenna 20, but also during a redeployment cycle. This configuration allows the antenna 20 to be more resilient in operation during specific mission scenarios and overcomes the technical drawbacks with current deployable conductive mesh and reflector antenna technologies.
The antenna 20 also minimizes and alleviates the requirement for adaptation of numerous types of stowage devices to organize and stow the various components of the antenna, including the flexible antenna reflector layer as the example conductive mesh 38. Different manufacturing techniques may be used and an example is shown in the high-level flowchart of
The process starts (Block 102) and the flexible support member 42 as the flexible strip that extends behind a flexible antenna reflector layer 38 is coupled between adjacent antenna ribs 22. This flexible strip 42 has first and second sets of openings 44,46 and adjacent antenna ribs 22 are relatively movable between first and second positions 30,32 (Block 104). The drawstring 50 that extends through the first set of openings 44 in the flexible support member 42 is coupled between adjacent antenna ribs 22 (Block 106). The method also includes coupling a plurality of tie cords 54 ending between the flexible antenna reflector layer 38 and the rear support cord 52 and passing through respective ones of the second set of openings 46 (Block 108). The process further includes coupling a biasing member 58 for maintaining tension in the drawstring 50 as adjacent antenna ribs 22 move between the first and second positions 30,32 so that the flexible support member 42 defines a pleated support body for the flexible antenna reflector layer 38 (Block 110). The process ends (Block 112).
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
