Abstract:
Reflector systems ( 10 ) comprising a reflector ( 11 ) formed from rigid panels ( 14 ) mounted on a centrally-located hub ( 12 ) are provided. The panels ( 14 ) can be stowed in a relatively compact manner in which the panels ( 14 ) overlap. The panels ( 14 ) can translate with a combination of rotational and linear motion so that the panels ( 14 ) become disposed in a side by side relationship, thereby deploying the reflector ( 11 ) so that the reflector ( 11 ) can focus electromagnetic energy incident thereupon.

Description:
BACKGROUND OF THE INVENTION 
     1. Statement of the Technical Field 
     The inventive arrangements relate to reflectors that focus electromagnetic energy in applications such as, but not limited to, radio-frequency (RF) antennae, solar collectors, cameras and other optical devices, etc. 
     2. Description of the Related Art 
     Reflectors used in RF antennas, solar collectors, optical devices, etc. are usually shaped so as to focus electromagnetic energy at a particular point or area, or in a particular direction, such as at an antenna feed system mounted on or proximate the reflector. Reflectors of this kind are commonly shaped to have a three-dimensional curved surface, such as a parabolic surface. Reflectors are usually configured in a solid or a mesh configuration. A solid reflector may comprise, for example, a rigid frame with a solid reflective skin mounted thereon. Wire mesh reflectors typically comprise a flexible metallic mesh supported on a framework of rigid, radially-oriented ribs. 
     Solid reflectors generally provide higher performance than mesh reflectors, i.e., a solid reflector usually will focus the electromagnetic energy incident thereupon with less loss as compared to a mesh reflector of the same or similar size. Moreover, the mesh of a mesh reflector may require individual positional or cord adjustments at hundreds or even thousands of locations thereon during its assembly and after deployment to achieve a required performance level. Even with such time-consuming and labor-intensive adjustments, it can be difficult to achieve a surface roughness, i.e., deviation from an ideal surface profile, of less that 0.010-inch (0.25 mm) in a mesh reflector. A surface roughness of 0.010-inch or less is generally required when the reflector is used to focus high-frequency RF signals such as Ka and Ku-band transmissions. Thus, the performance of wire-mesh reflectors is usually limited in such applications. 
     Mesh reflectors, however, can have advantages relating their stored volume. In particular, mesh reflectors usually can be folded into a compact configuration, thereby facilitating storage in relatively small volumes. A typical solid reflector, by contrast, is not foldable, and therefore has a larger ratio of stowed-to-deployed volume than a mesh reflector having an aperture of comparable size. This characteristic can be particularly disadvantageous in satellite and other space-based applications due to limitations on the size of the fairings in which the reflectors are typically stowed prior to deployment. Solid reflectors with apertures greater than 3.5 m typically need to be partitioned to fit in the fairing volume, making mesh reflectors more attractive for larger aperture reflectors. Thus, solid reflectors having apertures greater 3.5 meters (11.5 feet) diameter are not commonly used in space-based applications, or in airborne and other mobile applications. 
     SUMMARY OF THE INVENTION 
     Reflector systems comprising a reflector formed from rigid panels mounted on a centrally-located hub are provided. The panels can be stowed in a relatively compact arrangement in which the panels overlap. The panels are configured to translate with a combination of rotational and linear motion so that the panels become disposed in a side by side relationship, thereby deploying the reflector so that the reflector can focus electromagnetic energy incident thereupon. 
     A reflector system comprises a plurality of reflective panels, and a hub. The hub comprises a plurality of concentric rings each having a respective one of the panels mounted thereon, and an actuator mechanically coupled to the panels through the rings. The actuator is operable to move the panels between a stowed configuration wherein the panels are stacked in relation to each other, and a deployed configuration wherein the panels are positioned in a side by side relationship so that the panels form a reflector capable of focusing electromagnetic energy incident thereupon. 
     Another reflector system comprises a hub having a plurality of concentric rings. The system also comprises a plurality of rigid panels mounted on the rings and configured to move between a stowed configuration wherein the panels substantially overlap, and a deployed configuration wherein the panels form a reflector capable of focusing electromagnetic energy incident thereupon. 
     An antenna system comprises a feed system, and a reflector system. The reflector system comprises a hub and a plurality of rigid panels mounted on the hub. The panels are configured to move between a stowed configuration wherein the panels substantially overlap, and a deployed configuration wherein the panels form a reflector capable of focusing radio-frequency energy at the feed system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described with reference to the following drawing figures, in which like numerals represent like items throughout the figures and in which: 
         FIG. 1  is a perspective view of a reflector system, with panels thereof in a stowed configuration and a hub thereof in an extended configuration; 
         FIG. 2  is a perspective view of the reflector system shown in  FIG. 1 , with the panels moving between the stowed configuration and a semi-deployed configuration, and the hub in the extended configuration; 
         FIG. 3  is a perspective view of the reflector system shown in  FIGS. 1 and 2 , with the panels in the semi-deployed configuration and the hub in the extended configuration; 
         FIG. 4  is a perspective view of the reflector system shown in  FIGS. 1-3 , with the panels in a deployed configuration and the hub in a retracted configuration; 
         FIG. 5  is a perspective view of reflector system shown in  FIGS. 1-4 , with the panels in the stowed configuration and the hub in the extended configuration; 
         FIG. 6  is a perspective view of the reflector system shown in  FIGS. 1-5 , with the panels moving between the stowed and semi-deployed configurations and the hub in the extended configuration; 
         FIG. 7  is a perspective view of the reflector system shown in  FIGS. 1-6 , with the panels in the semi-deployed configuration and the hub in the extended configuration; 
         FIG. 8  is a perspective view of the reflector system shown in  FIGS. 1-7 , with the panels in the deployed configuration and the hub in the retracted configuration; 
         FIG. 9  is a cross-sectional view of the reflector system shown in  FIGS. 1-8 , taken along the line “B-B” of  FIG. 6 , with the panels in the stowed configuration and the hub in the extended configuration; 
         FIG. 10  is a cross-sectional view of the reflector system shown in  FIGS. 1-9 , taken along the line “B-B” of  FIG. 6 , with the panels in the deployed configuration and the hub in the retracted configuration; 
         FIG. 11  is a magnified view of the area designated “A” in  FIG. 5 ; 
         FIG. 12A  is a cross-sectional view of a synchronizer of the reflector system shown in  FIGS. 1-11 ; 
         FIG. 12B  is a side view of the synchronizer shown in  FIG. 12A ; 
       FIB.  12 C is a side view of an alternative embodiment of the synchronizer shown in  FIGS. 12A and 12B ; 
         FIG. 13  is a perspective view of an antenna system comprising the reflector system shown in  FIGS. 1-12B , depicting the reflector system mounted on a boom arm, with the panels of the reflector system in the stowed configuration and the hub in the extended configuration; 
         FIG. 14  is a perspective view of the antennas system shown in  FIG. 13 , with the panels of the reflector system in the deployed configuration and the hub in the retracted configuration; 
         FIG. 15  is a cross-sectional view of adjacent panels of the reflector system shown in  FIGS. 1-14 , equipped with a means for interlocking the panels thereof; 
         FIG. 16  is a cross-sectional view of adjacent panels of the reflector system shown in  FIGS. 1-15 , equipped with another means for interlocking the panels thereof; 
         FIG. 17  is a top view of adjacent panels of the reflector system shown in  FIGS. 1-16 , equipped with another means for interlocking the panels thereof; 
         FIG. 18  is a side view of the reflector system shown in  FIGS. 1-17 , equipped with another means for interlocking the panels thereof; 
         FIG. 19  is a side view of the reflector system shown in  FIGS. 1-18  mounted on a satellite and positioned with the satellite within the fairing of a launch vehicle, with the panels of the reflector system in the stowed configuration; and 
         FIG. 20  is a side view of four of the reflector systems shown in  FIGS. 1-18 , positioned within a common fairing of a launch vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operation are not shown in detail to avoid obscuring the invention. The invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the invention. 
     The figures depict a reflector system  10 . The reflector system  10  comprises a reflector  11 , and a hub  12 . The reflector  11  comprises ten solid-skin, rigid panels  14  mounted on the hub  12  via mounts  13  as shown in  FIG. 5 . The reflector system  10  can be configured in a stowed configuration shown in  FIGS. 1, 5, 9, 13, 19, and 20 , and a deployed configuration shown in  FIGS. 4, 8, 10, 14, and 18 . The panels  14  are vertically aligned, or stacked, when the reflector system  10  is in its stowed configuration, thereby facilitating storage of the reflector system  10  within a relatively small volume. Adjacent panels  14  are located side by side when the reflector system  10  is in its deployed configuration. 
     The reflector system  10  can be part of an antenna system  17 , which may be a Ka band antenna for example. The antenna system  17  can include a feed system  18  directly mounted to the reflector system  10 . The feed system  18  is depicted schematically in  FIGS. 13 and 14 . The feed system  18  can have a direct-fed, center-fed, offset-fed, or other configuration. The use of the reflector system  10  as part of a Ka-band antenna is disclosed for exemplary purposes only. The reflector system  10 , and alternative embodiments thereof, can be used as part of an antenna for other frequency bands, and can be used in other applications such as solar-energy collectors, cameras, and other optical devices. 
     The optimal number of panels  14  in the reflector system  10  is application-dependent, and can vary with operational requirements such as the diameter of the reflector  11 , the gain of the reflector  11 , the relative positions of the feed system  18  and the reflector  11 , the operating frequency of the feed system  18 , the stored volume of the reflector system  10 , etc. 
     Each panel  14  can include a core (not shown), and a solid external skin  22  that covers the core. The skin can be formed from, for example, graphite. The core can be formed from, for example, aramid, aluminum, or graphite, and can have a honeycomb structure. Specific materials for the core and the skin  22 , and a specific type of structure for the core are disclosed for exemplary purposes only. Other types of materials for the core and skin  22 , and other types of structures for the core can be used in the alternative. Moreover, the panels  14  can be formed from a rigid wire-mesh in alternative embodiments. 
     The panels  14  can be shaped so that the reflector  11  has a curved three-dimensional shape when deployed, as shown in  FIG. 4 . For example, the curved three-dimensional shape can be parabolic. The panels  14  of alternative embodiments can be shaped so that the reflector  11  has other types of curvature, or no curvature at all. 
     The skin  22  of each panel  14  preferably has a surface roughness of approximately 0.010-inch or lower, root mean square (RMS) to facilitate optimal reflection of high-frequency radio frequency (RF) signals. 
     The hub  12  can include a first or upper shell  30 , eight shells or rings  32 , and a second or lower shell  34 , as shown in  FIGS. 5, 7, and 9 . One of the panels  14  is mounted on the upper shell  30 , another panel is mounted on the lower shell  34 , and the remaining panels  14  are each mounted on an associated one of the rings  32 . 
     The upper shell  30 , rings  32 , and lower shell  34  are concentrically positioned about a central axis “X” of the hub  12 , and are nested within each other. The X axis is denoted in FIGS.  9  and  10 . The upper shell  30 , rings  32 , and lower shell  34  can translate in relation to each other in the axial (“X”) direction, to configure the hub  12  between an extended configuration shown in  FIGS. 1-3, 5-7, 9, 11, 19, and 20 , and a retracted configuration shown in  FIGS. 4, 8, 10, 14, and 18 . Moreover, the upper shell  30 , rings  32 , and lower shell  34  can rotate in relation to each other. 
     The upper shell  30 , rings  32 , and lower shell  34  are fully nested within each other, as depicted in  FIGS. 8 and 10 , when in the hub  12  is in its retracted configuration. The nested arrangement permits the reflector  11  to assume its fully deployed position in which the panels  14  are disposed in a side by side relationship. 
     The upper shell  30 , rings  32 , and lower shell  34  are partially nested within each other, as depicted for example in  FIGS. 1, 5, 9, and 11 , when the hub  12  is in its extended configuration. This arrangement facilitates the stacking of the panels  14  shown in  FIGS. 1, 5 , and  13 , which gives the reflector system  10  its relatively small footprint when in its stowed configuration. 
     Each ring  32  includes five substantially identical segments  50 . The optimal number of segments  50  in each ring  32  is application-dependent, and can vary with factors such as the overall size of the hub  12 . Each segment  50  is separated from its adjacent segments by notches  52  as shown, for example, in  FIGS. 5 and 11 . The segments  50  each include a raised projection  54  located at the approximate lengthwise mid-point of the segment  50 . Each notch  52  has a width, i.e., dimension along the circumferential direction of the ring  32 , that is slightly greater than that of the projections  54 , so that the projections  54  can fit within the notches  52 . Ball bearings or other low-friction devices can be used with, or in lieu of the projections  54  in alternative embodiments. 
     Each segment  50  also includes an end portion  56  as shown, for example, in  FIGS. 5 and 11 . The end portions  56  each have a vertical dimension, or height (from the perspective of  FIG. 5 ), that is greater than that of the adjacent portion of the segment  50 . 
     The upper shell  30  includes a ring portion  60 , and a plurality of struts  62  that adjoin the inner circumference of the ring portion  60 , as shown in  FIGS. 9 and 10 . The struts  62  extend downwardly and inwardly, and converge in a hub  66 . A plurality of projections  68 , substantially identical to the projections  54  on the segments  50  of the rings  32 , are formed on the ring portion  60 . Ball bearings or other low-friction devices can be used with, or in lieu of the projections  68  in alternative embodiments. 
     The lower shell  34  includes a ring portion  70 , and a flange portion  72  that adjoins a bottom edge of the ring portion  70 , as shown in  FIGS. 5, 9, and 10 . The lower shell  34  also includes a plurality of struts  74  that adjoin the flange portion  72 . The struts  74  extend downwardly and inwardly, and converge in a hub  78 . The ring section  70  includes a plurality of substantially identical segments  80 , as shown in  FIG. 5 . Each segment  80  has an end portion  82  that is substantially identical to the end portions  56  on the rings  32 . A plurality of notches  84 , substantially identical to the notches  52  on the rings  32 , are formed between each segment  80 . 
     The reflector system  10  can be mounted via the lower shell  34 . For example,  FIGS. 13 and 14  depict a space-based application in which the reflector system  10  is mounted at the end of a movable boom arm  200 , via mounts that are secured to the lower shell  34 . 
     The hub  12  also includes an actuator  90  as shown, for example, in  FIGS. 9 and 10 . The actuator  90  includes a rotary drive, such as an electric motor  92 , mounted on the hub  66  of the upper shell  30 . The motor  92  can be electrically coupled to a power source (not shown) on a selective basis, to facilitate activation and deactivation of the motor  92 . 
     The actuator  90  also includes a ball screw assembly comprising a ball screw  96  and a ball nut  98 , as shown in  FIGS. 9 and 10 . The ball screw  96  is coupled to the motor  92  so that the motor  92 , when activated, rotates the ball screw  96 . The term “coupled,” as used herein, is intended to denote both direct and indirect connections between two or more parts or components. The ball screw  96  extends through a centrally-located opening in the hub  66  of the upper shell  30 , and is rotatably coupled to the hub  66  via a bearing. The ball nut  98  is fixed to the hub  78 , within a centrally-located opening in the hub  78 . 
     The actuator  90  also includes a synchronizer  100 , depicted in  FIGS. 9, 10, 12A, and 12B . The synchronizer  100  is concentrically disposed around the ball screw  96 . The synchronizer  100  is coupled to the ball screw  96  on a selective basis via a first pin  104 , so that the synchronizer  100  rotates with the ball screw  96 . 
     The synchronizer  100  has a plurality of legs  101  that extend downwardly and outwardly, from the perspective of  FIGS. 9 and 10 . The legs  101  extend through slots  103  formed in the flange portion  72  of the lower shell  34 , and engage the flange portion  72 . The legs  101  thereby couple the lower shell  34  to the remainder of the synchronizer  100  and the ball screw  96 , so that the rotational motion of the ball screw  96  is transferred to the lower shell  34 . As discussed below, rotation of the lower shell  34  causes the upper shell  30  and the rings  32  to rotate, which in turn causes the panels  14  to move from their stacked or stowed configuration, to a semi-deployed configuration depicted in  FIGS. 3 and 7 . 
     The synchronizer  100  has an upper position, depicted in  FIGS. 9 and 12A . The synchronizer  100  has first slot  120  formed in a lower portion thereof, as shown in  FIG. 12A . The first pin  104  rests in the first slot  120  when the synchronizer  100  is in its upper position. The pin  104  engages the synchronizer  100  when disposed in the first slot  120 , thereby coupling the synchronizer  100  to the ball screw  96  so that the synchronizer  100  and the lower shell  34  rotate with the ball screw  96 . 
     The hub  66  of the upper shell  30  includes two tabs  108 , depicted in  FIGS. 9, 10, and 12A . Two pins  110  are mounted on respective tabs  108 , and extend inwardly, toward the X axis. The pins  110  are referred to hereinafter as “second pins  110 ,” for clarity. Only one of the second pins  110  and its associated tab  108  are depicted in  FIG. 12A , for clarity of illustration The second pins  110  selectively engage the synchronizer  100  via a circumferentially-extending second slot  112  formed in a upper portion of the synchronizer  100 , as depicted in  FIGS. 12A and 12B . 
     The synchronizer  100  is biased downwardly, from the perspective of  FIGS. 9, 10, 12A , and  12 B, by a spring (not shown). The synchronizer  100  is held in its upper position, against its spring bias, by the second pins  110 . 
     As discussed below, the second pins  110  can move out of the second slot  112  and thereby disengage from the synchronizer  100  when the panels  14  reach their semi-deployed configuration shown in  FIGS. 3 and 7 . The synchronizer  100  moves downwardly in response to its spring bias, to the position depicted in  FIG. 10 , upon disengagement of the second pins  110 . The first pin  104  no longer resides in the first slot  120  after the synchronizer  100  has moved downward, and the synchronizer  100  and ball screw  96  are thereby decoupled with respect to rotation, i.e., rotation of the ball screw  96  will not result in corresponding rotation of the synchronizer  100  and the lower shell  34 . 
     The ball screw  96  will rotate in relation to the ball nut  98  when the synchronizer  100  and the lower shell  34  are decoupled from the ball screw  96 . The rotation of the ball screw  96  in relation to the ball nut  98  causes the ball nut  98  and the lower shell  34 , to which the ball nut  98  is fixed, to move downwardly or upwardly in relation to the upper shell  30 , depending on the direction of rotation of the ball screw  96 , as depicted in  FIG. 10 . 
     The reflector  11  can be deployed in a two-step process. The panels are initially rotated from their stacked to their semi-deployed configuration, while the hub  12  remains in its extended configuration. The hub  12  is then moved axially, from its extend position to its retracted configuration, to bring the panels  14  into their side by side deployed relationship, thereby configuring the reflector  11  into its final parabolic profile. 
     Deployment of the reflector  11  is initiated by activating the motor  92 , which causes the attached ball screw  96  to rotate in relation to the motor  92 . At the start of the deployment process, as shown in  FIGS. 1, 5, and 14 , the panels  14  are vertically aligned, or stacked, and the hub  12  is in its extended configuration to facilitate the stacking of the panels  14 . Moreover, the second pins  110  are disposed within the second slot  112  on the synchronizer  100  as depicted in  FIG. 12 , so that the synchronizer  100  is held in its upper position and the first pin  104  remains positioned within the first slot  120  in the synchronizer  100 . The lower shell  34 , therefore, is coupled for rotation with the ball screw  96  via the synchronizer  100 . 
     The motor  92 , upon activation, exerts a torque on the ball screw  96 . The ball screw  92 , in turn, exerts a reactive torque on the motor  92 . The lower shell  34  is fixed in relation to the structure adjacent to the reflector system  10 , and the ball screw  92  is fixed to the lower shell  34  via the first pin  104 . Therefore, the reactive force exerted by the ball screw  96  on the motor  92  causes the upper shell  30 , to which the motor  92  is fixed, to rotate in relation to the ball screw  96  and the lower shell  34 . The upper shell  30  can also rotate in relation to the rings  32 . 
     The rotation of the upper shell  30  eventually causes each of the projections  68  on the upper shell  30  to abut an end portion  56  of one of the segments  50  on the adjacent, or uppermost ring  32  as depicted in  FIG. 6 . The end portions  56 , as discussed above, each have a height that is greater than the height of the adjacent portion of the segment  50 . This feature facilitates the abutment of the projections  68  and the segments  50  of the adjacent ring  32 . 
     Further rotation of the upper shell  30  after the projections  68  have contacted the end portions  56  of the adjacent ring  32  causes the adjacent ring  32  to rotate along with the upper shell  30 , i.e., the adjacent ring  32  is pushed in the direction of rotation of the upper shell  30  by the projections  68 . 
     Continued rotation of the upper shell  30  and the uppermost ring  32  eventually causes the projections  54  on the uppermost ring  32  to contact the end portions  56  on the segments  52  of its adjacent, or second highest ring  32 , as shown in  FIG. 6 . The engagement of the projections  54  and the end portions  56  causes the second highest ring  32  to rotate along with the upper shell  30  and the uppermost ring  32 . Because the hub  12  at this point remains in its extended configuration, the axial (X-axis) positions of the upper shell  30  and the rings  32  remain substantially constant as the upper shell  30  and the rings  32  rotate about the X axis. 
     The above deployment process continues as the upper shell  30  continues to rotate, with each ring  32  causing its adjacent ring  32  to rotate, until the lowermost ring  32  has been rotated so that its projections  54  engage the end portions  82  on the ring portion  70  of the lower shell  34  as shown in  FIG. 7 . The panels  14  at this point are in their semi-deployed configuration in which all of the panels  14  have assumed their final angular, or clock position about the X axis as depicted in  FIGS. 3 and 7 . Moreover, each projection  68 ,  54  on the upper shell  30  and the rings  32  is aligned with a corresponding notch  52 ,  84  on the rings  32  or the lower shell  34  at this point. 
     Until this point in the deployment process, the engagement of the first pin  104  and the synchronizer  100  has prevented relative rotation between the lower shell  34  and the ball screw  96 . Thus, the ball screw  96  has not rotated in relation to the ball nut  98 , the relative axial positions of the lower shell  34  and the ball screw  96  have remained the same, and the hub  12  has remained in its extended position. 
     As discussed above, the engagement of the synchronizer  100  and the second pins  110  hold the synchronizer  100  in its upper position, causing the first pin  104  to remain in the first slot  120  in the synchronizer  100 , which in turn causes the ball screw  96  and the lower shell  34  to remain coupled to the synchronizer  100 . 
     The hub  12  is configured so that the second pins  110  can exit the second slot  112  as the panels  14  reach their semi-deployed configuration, thereby permitting the synchronizer  100  to move to its lower position. When the synchronizer  100  is in its lower position, the first pin  104  is disengaged from the first slot  120 , and the synchronizer  100  thereby is decoupled from the first pin  104  and the ball screw  96 , which in turn permits the hub  12  to retract as discussed below. 
     Disengagement of the second pins  110  from the second slot  112  can be effectuated through the use of two slots  116  formed in the synchronizer  100 , as shown in  FIG. 12A . The slots  116  are referred to hereinafter as “third slots  116 ,” for clarity. The third slots  116  adjoin the second slot  112 . The second pins  110  can exit the second slot  112  via the third slots  116  when the second pins  110  each becomes aligned with one of the third slots  116 , as shown in  FIG. 12A . 
     The synchronizer  100  can be configured so that the second pins  110 , which are mounted on the upper shell  30 , each align with a respective one of the third slots  116  as the upper shell  30  reaches the end of its rotational movement, which coincides with the panels  14  reaching their semi-deployed configuration. When the second pins  110  align with the third slots  116 , the second pins  110  can exit the synchronizer  100  so that the synchronizer  100  is no longer held in its upper position by the second pins  110 , and the synchronizer  100  can move downwardly under its spring bias to its lower position, as denoted by the arrow  119  in  FIG. 12B . The synchronizer  100  and the lower shell  34  thereby become decoupled from rotation with the ball screw  96  when the panels  14  reach their semi-deployed configuration. 
       FIG. 12C  depicts an alternative embodiment of the synchronizer  100  in the form of a synchronizer  100   a . The synchronizer  100   a  has a spiral slot  112   a  formed therein for receiving the second pins  110 . The synchronizer  100   a  rotates with the upper shell  30  when the first pin  104  engages the synchronizer  100   a  via a first slot (not shown) in the synchronizer  100   a . The first slot of the synchronizer  100   a  is substantially identical to the first slot  120  of the synchronizer  100 . 
     Rotation of the synchronizer  100   a  in relation to the second pins  110  causes the second pins  110  to travel gradually toward the open end of the second slot  112   a . The spiral configuration of the slot  112   a  causes the second pins  110  to cam, or urge the synchronizer  100   a  downward as the synchronizer  100   a  rotates in relation to the second pins  110 . The second slot  112   a  is configured so that one of the second pins  110  exits the second slot  112   a  before the shell  30  reaches the end of its rotational movement, and the other one of the second pins  110  exits the slot  112   a  as the shell  30  reaches the end of its rotational movement and the synchronizer  100   a  reaches a lower position as shown in  FIG. 12C . 
     The first pin  104  disengages from the first slot when the synchronizer  100   a  reaches its lower position. The synchronizer  100   a  thereby becomes decoupled from rotation with the ball screw  96  when the upper shell  30  reaches the end of its rotational movement and the panels  14  reach their semi-deployed configuration, and the hub  14  can move to its retracted position as discussed below. 
     The ball nut  98  is fixed to the lower shell  34 . The ball screw  96  thus rotates in relation of the ball nut  98  once the lower shell  34  has been decoupled from the ball screw  96 . Because the reflector system  10  is mounted via the lower shell  34 , the lower shell  34  and the attached ball nut  98  remain stationary in relation to the rotating ball screw  96 . Rotation of the ball screw  96  in relation to the stationary ball nut  98  causes the ball screw  96  to translate downwardly, or “walk down,” the ball nut  98  as shown in  FIGS. 9 and 10 . Because the ball screw  96  is coupled to the motor  92 , and the motor  92  is fixed to the upper shell  30 , the downward motion of the ball screw  96  imparts a corresponding downward motion to the upper shell  30  in relation to the lower shell  34 . 
     The downward movement of the upper shell  30  causes the ring portion  60  of the upper shell  30  to retract, or nest, within the adjacent, or uppermost ring  32  as depicted in  FIGS. 8 and 10 . The retraction of the ring portion  60  within its adjacent ring  32  causes the two panels  14  associated with the upper shell  30  and the uppermost ring  32  to assume their side by side, or deployed relationship, and also causes the projections  68  on the upper shell  30  to become disposed within the notches  52  of uppermost ring  32 . 
     The mount  13  of the panel  14  associated with the upper shell  30  contacts the upper edge of the adjacent, or uppermost ring  32  when the ring portion  60  of the upper shell  30  has fully retracted into the uppermost ring  32 , as shown in  FIGS. 8 and 10 . This contact, in conjunction with the continued downward movement of the upper shell  30 , cause the mount  13  to urge the uppermost ring  32  downwardly, so that the uppermost ring  32  retracts within the adjacent ring  32 , and the projections  54  on the uppermost ring  32  become disposed within the notches  52  on the adjacent ring  32 . At this point, the panels  14  associated with the upper shell  30  and the uppermost two rings  32  have assumed their side by side deployed relationship. 
     As the retraction process continues, each ring  32  retracts or nests within its adjacent ring  32 , and the projections  54  of each ring  30  become disposed within the notches  52  the adjacent ring  32  as the mounts  13  associated with the upper shell  30  and the higher rings  32  urge each successive ring  32  downward. Alternatively, the projections  68 ,  54  on the upper shell  30  and the rings  32  can be configured so that the projections  68 ,  54 , rather than the mounts  13 , exert a downward force on the rings  32  during the retraction process. 
     The lowermost ring  32  eventually retracts within the ring portion  70  of the lower shell  34 , and the projections  54  of the lowermost ring  52  become disposed within the notches  84  in the lower shell  34 . The hub  12  at this point has been fully retracted, and the motor  92  can be deactivated based on input from a suitable sensor such as a limit switch (not shown). Alternatively, or in addition, the motor  92  can be equipped with a clutch (not shown) that causes the motor  92  to disengage from the ball screw  96  when the hub  12  has been fully retracted. All of the panels  14  at this point are in a side by side relationship, and the reflector  11  is in its fully deployed parabolic configuration as depicted in  FIGS. 4, 8, 10, 14, and 18 . 
     It is believed that the above deployment process, when conducted under one-g or zero-acceleration conditions, can be performed without the use, or with minimal use of counter-balance tooling. 
     If required or otherwise desired for a particular application, the actuator  90  can be configured so that the reflector  11  can be returned to its stowed configuration after being deployed. In particular, the motor  92  can be reversed so that the ball nut  98  walks up the ball screw  96 , thereby moving the hub  12  from its retracted to its extended configuration, which in turn moves the panels  14  from their deployed to their semi-deployed configuration. The synchronizer  100  can be equipped with provisions (not shown) that move the synchronizer  100  upward at this point, so that the first pin  104  becomes disposed in the first slot  120  of the synchronizer and thereby re-engages the synchronizer  100 , thereby coupling the ball screw  96  and the lower shell  34 . Reverse operation of motor  92  after this point will rotate the panels  14  from their semi-deployed to their stacked configuration. 
     A particular configuration for the actuator  90  has been disclosed herein for exemplary purposes only. Virtually any type of mechanism that can generate the above-described rotational and axial movement of the various components of the reflector system  10  can be used as the actuator  90 . For example, in one possible alternative embodiment, a lead screw can be used in lieu of the ball screw assembly. In other alternative embodiments, the actuator  90  can include two motors. One of the motors can be used to effectuate the rotational movement of the panels  14 , and the other motor can be used to effectuate the linear or axial movement of the various components of the hub  12 . In other alternative embodiments, one or more hydraulic or pneumatic actuators can be used in lieu of the motor  92 . 
     The reflector system  10  can include provisions to secure the ends of adjacent panels  14  to each other when the reflector  11  is in its deployed configuration. For example, each panel  14  can be equipped with plungers or detent pins  130  positioned along one or both of its left and right edges.  FIG. 15  depicts the detent pins  130  positioned along the right edge of each panel  14 . The detent pins  130  can engage the opposing panel  14  via recesses  132  formed in the opposing panel  14 , as the hub  12  is retracted and the adjacent panels  14  are drawn together into their side by side deployed relationship. The engagement of the detent pins  130  and the adjacent panel  14  secures the panels  14  to each other while the reflector  11  is deployed. The detent pins  130  thus act as means for interlocking the panels when the panels  14  are in the deployed configuration. 
     Spring-loaded latches (not shown) can be used in lieu of the detent pins  130  in alternative embodiments. Each latch can have a spring-load pin that engages an adjacent panel  14  via a penetration formed in the adjacent panel in lieu of the recesses  132 . 
     In an alternative embodiment, a toothed spline  140 , shown in  FIG. 17 , can be mounted on the left edge of each panel  14  (as viewed from the perspective of  FIG. 17 ). The spline  140  can be mounted using pins (not shown) or other means that permit a limited degree of movement of the spline  140  along the edge of the panel  14 . 
     A plurality of pins  142  can be mounted proximate the right edge of each panel  14 . The pins  142  and the spline  140  can be positioned so that each pin  142  aligns with an area  144  defined by one of the teeth  146  of the spline  140  on an adjacent panel  14 , when the panels  14  are rotated into their semi-deployed configuration. Each pin  142  becomes disposed in the associated area  144  as the hub  12  is retracted and the adjacent panels  14  are drawn together into their side by side relationship. 
     The spline  140  can subsequently be pulled inwardly toward the central X axis, in the direction denoted by the arrow  146 . Additional pins  148  can be mounted on each panel  14  proximate the spline  140 , as shown in  FIG. 17 . The pins  148  engage angled surfaces  150  on the side of the spline  140  opposite the teeth  146 . The interaction between the angle surfaces  150  and the pins  148  urges the teeth  146  of the spline  140  against the associated pins  142 , thereby securing the adjacent panels  14  to each other via the teeth  146  and the spline  140 . The splines  140  can be pulled inwardly via a suitable means such as cabling drawn around a spool (not shown) coupled for rotation with the ball screw  96 . 
     In another alternative embodiment, magnetic elements  150  can be mounted on the edges of each panel  14  as shown in  FIG. 16 . The magnetic elements  150  can be positioned so that the magnet elements  150  on adjacent panels  14  align when the panels  14  reach their side by side deployed configuration. The resulting magnetic attraction between the magnetic elements  150  can secure the adjacent panels  14  to each other. 
     In another alternative embodiment, depicted in  FIG. 18 , the panels  14  can have stepped edges, and cables  160  can be used to exert a downward force on each panel  14  to force the overlapping steps on adjacent panels  14  together, thereby securing the adjacent panels  14  to each other. 
     The reflector system  10  permits a solid reflector to be stored in a compact volume. Thus, the high performance of a solid reflector can be achieved, while at the same time achieving the relatively low storage volume usually associated with flexible wire-mesh reflectors of lesser performance. 
     Moreover, as a result of the solid-panel configuration, there is no need to make hundred or thousands of cord adjustments to the reflector before and after deployment, as may be required with a flexible wire-mesh reflector to achieve the requisite surface roughness. Also, the solid-panel configuration of the reflector  11  is believed to a more predictable or determinate deployment than a flexible mesh reflector since there are no cords to manage during launch in space-based applications. Moreover, it is believed that the number of parts, and the overall cost of a stowable, solid-panel reflector such as reflector  11  are less than that of a wire-mesh reflector of comparable size and surface roughness. 
     For example, it is predicted that a solid-panel reflector having an aperture of approximately five meters, constructed with foldable panels as in the reflector system  10 , will have a comparable, or potentially smaller stowed volume than a five-meter diameter radial ribwire mesh reflector. 
     Moreover, the predicted height of the five-meter solid-panel reflector, i.e., the dimension along the lengthwise direction of the stacked panels  14 , is approximately 114.5 inches (2.91 meters). The height of the five-meter mesh reflector, by contrast, is approximately 131.7 inches (3.35 meters). This height difference is attributable to the non-scalloped edges of the solid reflector  11 , which result in a smaller overall diameter for a solid reflector having the same effective aperture as a flexible wire-mesh reflector with scalloped edges. 
     The use of the reflector system  10  can thus facilitate the use of relatively large, e.g., five-meter aperture or greater, solid reflectors in applications, e.g., satellite communications, where the use of reflectors of such size would not otherwise be possible or practicable. For example,  FIG. 19  depicts the reflector system  10  mounted on a communications satellite  182 , with the reflector  10  and the satellite  182  installed in a fairing  180  of a launch vehicle. 
       FIG. 20  depicts four of the reflector systems  10  installed in a frusto-conical tip portion of a launch-vehicle fairing  186 , with each reflector system  10  being mounted on a movable boom arm  200 . Each reflector system  10  can be held in place prior to deployment by restraints (not shown) connected to the fairing  186 .