Abstract:
A deployable reflector for an electronically scanned reflector antenna is provided. The deployable reflector may be confined to a relatively small volume for transportation of the reflector to a deployment site. Upon deployment, the reflector of the present invention forms a relatively large reflector surface, having a precisely controlled surface geometry. The reflector generally includes a plurality of panel members interconnected to a plurality of ribs interconnected to an extendable boom. The antenna reflector of the present invention is particularly well suited for a space-based antenna, where a reflector that can be collapsed into a small volume for transport and deployed to form a large reflector surface having high gain is desirable.

Description:
FIELD OF THE INVENTION 
     The present invention relates to radio frequency antennas employing reflectors. In particular, the present invention relates to a deployable reflector for an electronically scanned antenna system. 
     BACKGROUND OF THE INVENTION 
     Antennas are used to radiate or receive radio wave signals. The transmission and reception of radio wave signals is useful in a broad range of activities. For instance, radio wave communication systems are desirable where communications are transmitted over large distances. 
     One type of antenna for use with radio wave communications is the reflector antenna. Reflector antennas typically feature a relatively large reflector surface, to increase the gain of the antenna. The reflector surface may take any one of a number of geometrical configurations, such as plane, corner, and curved configurations 
     An electronically scanned reflector antenna is an antenna that uses a phased array feed to illuminate a nearby reflector unit in order to generate one or more steerable antenna beams. Such antennas are increasingly used in space-based applications such as, for example, satellite communications applications. As can be appreciated, it is difficult to transport large antenna reflectors into space. Therefore, it is desirable to have a deployable reflector that can be collapsed into a relatively small volume for transport, and deployed as a relatively large reflector surface at the antenna site. 
     It is desirable that a reflector for an antenna be relatively inexpensive to construct. In addition, it is desirable that such a reflector have a precisely controlled surface geometry to ensure the highest possible antenna efficiency. Previously, deployable antennas using fabric-type reflector surfaces have been constructed from single pieces of fabric or several large pieces. Such reflector assemblies are expensive and difficult to manufacture, as it is difficult to control the shape of large pieces of fabric, particularly where the reflector has a curved surface. Other fabric-type reflectors have used relatively small, complex pieces of fabric that are joined to one another, again resulting in a reflector that is difficult and expensive to manufacture. Still other fabric type reflectors use an “umbrella” type deployment mechanism having the shape of a paraboloid, with ribs that are bowed, and therefore shaped, by the fabric of the reflector surface. In addition, previous fabric-type antenna reflector designs have been incapable of providing a large reflector surface having a precisely controlled surface geometry to provide high gain, a small storage volume, and a reliable deployment mechanism in a space-based antenna application. 
     Therefore, there is a need for a method and apparatus for providing a large reflector surface for space-based antenna applications. In particular, there is a need for a method and apparatus for providing such a reflector that can be stowed in a relatively small volume for transportation to the antenna site, and deployed at the site automatically to provide a reflector surface having high gain. Furthermore, there is a need for a large reflector surface suitable for use in connection with an electronically scanned reflector antenna system. In addition, such a method and apparatus should be relatively easy to manufacture and operate. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a deployable antenna reflector for a space-based antenna system is disclosed. The reflector generally includes a plurality of fabric panel members and a connecting assembly interconnected to the panel members, and movable from a stowed state into a deployed state. In a stowed state, the components of the connecting assembly are within a relatively small distance of one another, and the fabric of the plurality of panel members is folded. In a deployed stated, the components of the connecting assembly are moved apart from one another to hold the panel members in tension, thereby forming a reflector surface. 
     The panel members generally comprise identical panels of fabric or metallized flexible dielectric sheets, each having associated attachment members. The attachment members provide a convenient means for attaching the panel members to the connecting assembly. In addition, the provision of the panel members in one or a small number of sizes facilitates assembly of the reflector, and reduces the cost of the reflector. 
     The connecting assembly generally includes ribs having contoured front surfaces for shaping the panel members and thus the reflector when the reflector is in a deployed state. The ribs are generally carried by an extendable boom. 
     When the reflector is in a stowed state, the ribs are in relatively close proximity to one another. According to one embodiment of the present invention, each rib can also be folded about a centrally located hinge, so that the reflector can be placed in a relatively small container for transportation. Upon deployment, the ribs are opened about the centrally located hinges, and the boom is extended, moving the interconnected ribs apart from one another. The extension of the boom additionally tensions the panel members, which are held between adjacent ribs, forming the reflector surface. According to one embodiment of the present invention, adjacent panel members in a row are affixed to the same pair of ribs, but are not directly interconnected to one another. 
     For use as part of an antenna system that will be located in a remote location such as the polar regions of Earth or in space, the reflector assembly is placed in a first, or folded, condition, and is transported to the antenna site. Once at the antenna site, the reflector assembly is placed in a second, deployed state in which the plurality of panels is held in tension between individual ribs of the connection assembly to form a reflector surface. 
     The present invention includes a method of forming panel members for use in a deployable antenna reflector. According to this method, a foldable fabric having a surface capable of reflecting electromagnetic radiation is formed into regularly sized panels. The panels are affixed at a first end to a first attachment member, and at a second end to a second attachment member. The panels are next placed under a predetermined amount of tension, and holes are formed through the first and second ends of the panel. The panel is then ready for use in a reflector assembly. 
     Based on the foregoing summary, a number of salient features of the present invention are readily discerned. An antenna reflector having a large surface area when deployed, but requiring a small volume for transport, can be provided. The antenna reflector provides a high gain, due to its large size and precise surface control. The antenna reflector is well suited for use in space-based applications, as it can be compactly stowed for transportation to the antenna site, and deployed at the site without direct human intervention. The antenna reflector can be formed from a plurality of like-sized panels to increase the accuracy of the reflector surface when deployed, and to decrease manufacturing costs. 
     Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an electronically scanned reflector antenna system in accordance with the present invention, with the reflector shown in a deployed condition; 
     FIG. 2 is a plan view of a rib of a reflector assembly in accordance with the present invention; 
     FIG. 3A is a side view of an electronically scanned reflector antenna system in accordance with the present invention with the reflector shown in a collapsed condition in the payload container of a spacecraft; 
     FIG. 3B is a top view of an electronically scanned reflector antenna system in accordance with the present invention with the reflector shown in a collapsed condition in the payload container of a spacecraft; 
     FIG. 4 is a perspective view of the rear of a reflector assembly of an electronically scanned reflector antenna system in accordance with the present invention in a deployed condition; 
     FIG. 5 is an exploded view of a panel member in accordance with the present invention; 
     FIG. 6 is a partial side view of a panel member in accordance with the present invention; 
     FIG. 7 is a perspective view of a panel member in accordance with the present invention, shown in a partially folded condition; 
     FIG. 8 is a partial perspective view of the front of a reflector assembly in accordance with the present invention; 
     FIG. 9 is another partial perspective view of the front of a reflector assembly in accordance with the present invention; 
     FIG. 10 is yet another perspective view of the front of a reflector assembly in accordance with the present invention; 
     FIG. 11 is a perspective view of a panel member in accordance with the present invention; and 
     FIGS. 12A-E illustrate the deployment of a reflector assembly in accordance with the present invention from a collapsed condition to a deployed condition. 
    
    
     DETAILED DESCRIPTION 
     In accordance with the present invention, a deployable reflector for an electronically scanned reflector antenna system is provided. 
     With reference to FIG. 1, an electronically scanned reflector antenna system  100  having a deployable reflector assembly  104  is illustrated. As illustrated in FIG. 1, the antenna system  100  includes, in addition to the reflector assembly  104 , a feed assembly  108 . The feed assembly  108  includes a feed  112  and a positioning member  116 . Generally, the reflector assembly  104  serves to direct radio waves received from a remote source (not shown) to the feed  112  of the feed assembly  108 . Additionally, the reflector assembly  104  directs radio waves transmitted from the feed  112  towards a remote source (not shown). Accordingly, the feed  112  is preferably positioned by the positioning member  116  so that it is located at the focal point of the reflector  104 . Although the front surface  120  of the reflector assembly  104  illustrated in FIG. 1 describes a parabolic cylinder, reflector assemblies  104  in accordance with the present invention additionally include assemblies  104  having a front surface  120  that is planar, that is circular, that is shaped but cylindrical, or that forms a corner type reflector. 
     The reflector assembly  104  generally includes a plurality of panel members  124  and a connecting assembly  128 . The connecting assembly  128  includes a boom  132 , interior ribs  136   a-d,  and end ribs  140   a-d.  Each of the interior ribs  136   a-d  is divided into first  144   a-d  and second  148   a-d  subassemblies. Similarly, each of the end ribs  140   a-d  is divided into first  152   a-d  and second  156   a-d  subassemblies. In the deployed state or condition of the reflector assembly  104  illustrated in FIG. 1, the boom  132  is in an extended position, and the panel members  124  are held in tension between the end ribs  140   a-d.  Where the panel members  124  are of like size, the ribs  136  and  140  are parallel to one another when the reflector assembly is in a deployed condition. 
     The ribs  136  and  140 , together with the panel members  124  cooperate to form the reflector  160  of the reflector assembly  104 . The reflector  160 , in the embodiment illustrated in FIG. 1, is generally divided into two subassemblies. The first reflector subassembly  164  includes end ribs  140   a  and  140   b,  interior ribs  136   a  and  136   b,  and the panel members  124  affixed to those ribs  136   a-b  and  140   a-b.  The second reflector subassembly  168  of the reflector  160  generally includes end ribs  140   c  and  140   d,  interior ribs  136   c  and  136   d,  and the panel members  124  attached to those ribs  136   c-d  and  140   c-d.  Accordingly, the end ribs  140   a  and  140   b  of the first subassembly  164  of the reflector  160  cooperate to hold the panel members  124  positioned between the end ribs  140   a  and  140   b  in tension, while the interior ribs  136   a  and  136   b  assist in maintaining the desired surface geometry of the reflector  160 . Similarly, end ribs  140   c  and  140   d  of the second subassembly  168  of the reflector  160  cooperate to hold the panel members  124  located between the end ribs  140   c  and  140   d  in tension, while the interior ribs  136   c  and  136   d  assist in maintaining the desired geometry of the second subassembly  168  of the reflector  160 . 
     Although the embodiment illustrated in FIG. 1 includes first  164  and second  168  subassemblies, such a configuration is not necessary to the present invention. For example, the reflector  160  could be comprised of one pair of end ribs  140  with any number of interior ribs  136 , including no interior ribs  136 . Additionally, the reflector  160  can, according to the present invention, be formed from more than two reflector subassemblies  164  and  168 . In yet another embodiment of the reflector  160  illustrated in FIG. 1, the first  164  and second  168  reflector subassemblies may share an end rib  140 . For instance, end ribs  140   b  and  140   c  may comprise a single end rib  140 . 
     In the embodiment illustrated in FIG. 1, a row of like-sized panel members  124  is held between each adjacent pair of ribs  136  and  140 . The ribs  136  and  140  are contoured on a front side  172  corresponding to the front surface  120  of the reflector assembly  104 . (See FIG.  2 ). The contoured surface  172  enables the ribs  136  and  140  to impart a curvature or arc to the panel members  124  when the panel members  124  are held in tension between the ribs  136  and  140 . This is because the panel members  124  are mounted to the ribs  136  and  140  in such a way that they follow the curve of the front surface  172  of the ribs  136  and  140 . The contoured front surface  172  of the ribs  136  and  140  provides the reflector assembly  104  with the curvature required to form a reflector  160  having a generally parabolic, circular or shaped cross section to direct radio waves incident on the reflector  104  to the feed  112 . Of course, where the reflector  160  is planar, the front surface  172  of the ribs  136  and  140  will be linear, rather than curved. In addition, the ribs  136  and  140  may have a front surface  172  comprised of a series of straight segments, so that the ribs  136  and  140  approximate a curve over the entire length of the ribs  136  and  140 . Preferably, each panel member  124  is attached to the ribs  136  and  140  such that it abuts, but does not overlap, adjacent panel members  124 . According to one embodiment of the present invention, adjacent panel members  124  in a row of panel members  124  are interconnected to the same adjacent ribs  136  and  140 , but are not directly interconnected to one another. 
     With reference now to FIGS. 3A and 3B, the antenna system  100 , including a reflector assembly  104  according to the present invention, is illustrated in a collapsed condition. In FIG. 3A a side view of the antenna system  100  enclosed within a spacecraft fairing  300  is illustrated, while in FIG. 3B a top view of the antenna system  100  enclosed in a spacecraft fairing  300  is illustrated. 
     When the reflector assembly  104  is in a collapsed state, the boom  132  of the reflector assembly  104  is also in a collapsed configuration. With the boom  132  in a collapsed configuration, each of the ribs  136  and  140  is at a relatively short distance from its immediately adjacent rib or ribs  136  and/or  140 , and the panel members  124  are folded between the ribs  136  and/or  140 . Referring now to FIG. 3B, the reflector assembly  104  is shown with the subassemblies or halves  144 ,  148 ,  152  and  156  of the ribs  136  and  140  (of which only one end rib  140   d  with corresponding halves  152   d  and  156   d  is visible in FIG. 3B) folded about a rib hinge  304 . Each of the ribs  136  and  140  has an associated hinge, which  304  interconnects the halves  144  and  148  or  152  and  156  of the ribs  136  or  140 . The use of hinges  304  to interconnect the ribs halves  144  and  148 , and  152  and  156  allows the ribs  136  and  140  to be folded as illustrated in FIGS. 3A and 3B, while allowing the ribs  136  and  140  to form a relatively large member when opened about the hinges  304 . 
     The feed assembly  108  is shown in FIG. 3B with the positioning member  116  divided into first  306  and second  307  portions. The positioning member  116  is folded at a positioning member hinge  308 , and the feed assembly  108  is further folded at a reflector assembly hinge  312 , such that the feed  112  and the feed positioning member  116  are generally located between the folded ribs  136  and  140  of the reflector assembly  104 . As illustrated in FIGS. 3A and 3B, the reflector assembly  104 , in a collapsed state, can be located within the relatively small confines of a spacecraft fairing  300 . 
     With reference now to FIG. 4, the reflector assembly  104  is illustrated from a rear perspective view, in a deployed state. This view of the reflector assembly  104  most clearly shows the ribs  136  and  140  that support the panel members  124  when the reflector assembly  104  is in a deployed configuration. The embodiment of the reflector assembly  104  illustrated in FIG. 4 is larger than the reflector assembly  104  illustrated in FIG. 1, and therefore features additional interior ribs  136   e-j  and additional panel members  124 . In other respects, the embodiment of the reflector assembly  104  illustrated in FIG. 4 is similar to the embodiment of FIG.  1 . 
     When in the deployed configuration, each of the ribs  136  and  140  are opened about their associated hinges  304  (see FIG.  3 B), and the boom  132  is extended. The boom  132  is interconnected to the end ribs  140  by a tensioning assembly  400 . According to one embodiment of the invention, the interior ribs  136  are not directly connected to the boom  132 . In the deployed configuration, the panel members  124  are held in tension between the ribs  136  and  140 . 
     The end ribs  140  are generally constructed so that they are stronger than the interior ribs  136 . Thus, according to one embodiment, such as the one illustrated in FIG. 4, the end ribs  140  may be larger in cross section than the interior ribs  136 . The end ribs  140  must be stronger than the interior ribs  136  because the end ribs  140  are required to spread the tensioning force introduced by the tensioning assembly  400  along the length of the rib  140  and to the attached panel members  124 . In contrast, the interior ribs  136  are subjected to substantially equal and opposite tensioning forces introduced by the attached opposite rows of panel members  124 . Therefore, the interior ribs  136  are not required to have as much strength as the end ribs  132 . All of the ribs  136  and  140 , however, should be sufficiently stiff so that the desired curvature of the reflector  160  is maintained when the reflector  160  is deployed. Furthermore, all of the ribs  136  and  140  are preferably strong enough that they are not deformed by the force introduced by the tensioning assembly  400  when the reflector assembly  104  is deployed. 
     According to one embodiment of the present invention, the amount of tension in the panel members  124  is limited by limiting members  404 . The limiting members  404  extend between adjacent ribs  136  and  140  and determine the maximum distance between the adjacent ribs  136  and  140 , thereby limiting the amount of tension transferred to the panel members  124 . According to one embodiment, the limiting members  404  are catenary belts, which are formed from a flexible material so that they can fold with the panel members  124  when the reflector assembly  104  is in a collapsed state. The limiting members  404  are preferably substantially inelastic. In an alternative embodiment, the limiting members  404  may comprise a pantograph formed from stiff pieces of material. 
     With reference now to FIG. 5, each panel member  124  includes a panel  500  and first and second attachment members  504  and  508 . Generally, the panels  500  are constructed from a metalicized mesh material that can be folded, and that is capable of reflecting electromagnetic radiation. The panel  500  may be in the shape of a parallelogram, such as the rectangle illustrated in FIG. 5, having a first end  512  and a second end  516 , and a first free edge  520  and a second free edge  524 . According to one embodiment, each of the panel members  124  of a reflector  160  are the same size. For example, the panel members  124  may be 1.5 m long (along each of the first  520  and second  524  free edges) by 0.5 m wide (along each of the first  512  and second  516  ends). According to the embodiment illustrated in FIG. 5, the attachment members  504  and  508  feature holes  528  that correspond to holes  532  in the panel  500 . Fasteners  536  may then be used to extend through the holes  528  and  532  to join the attachment members  504  and  508  to the panels  500 . Alternatively or in addition, the attachment members  504  and  508  may be joined to the panels  500  with adhesive. 
     The attachment members  504  and  508  are generally rectangular in shape, and each attachment member  504  and  508  is designed to support the tension introduced to the individual panel member  124  with which the particular attachment member  504  or  508  is associated without buckling. Where the attachment members  504  and  508  are attached to the front side  172  of the ribs  136  and  140 , each attachment member  504  or  508  should be of sufficient length to extend along the end  504  or  508  of the panel member  124  with which the particular attachment member  504  or  508  is associated. This ensures that the panels  500  are evenly supported along their entire width and allows the panel members  124  to follow the curvature of the ribs  136  and  140  over the length of the panel  500 . Accordingly, the dimensions of the attachment members  504  depend, at least in part, on the length of the panel member  124  ends  512  and  516  to which a particular attachment member  504  or  508  is associated, on the tension that the attachment member  504  or  508  is intended to support, on the particular method and configuration by which tension is transferred from the ribs  136  and  140  to the panel members  124  and on the material from which the attachment member  504  or  508  is constructed. For example, the attachment members  504  and  508  of a panel member  124  that is affixed to the ribs  136  and  140  using an adhesive could have a smaller thickness and be smaller in a direction parallel to the free edges  520  and  524  of the panel  500  than the attachment members  504  and  508  of like material of a panel member  124  that is affixed to the ribs  136  and  140  using fasteners  536 . This is because the tensioning force imparted by the ribs  136  and  140  is relatively evenly distributed along an attachment member  504  or  508  affixed to a rib  136  or  140  using adhesive along the ends  512  and  516  of the panel member  124 , while fasteners  536  concentrate the tensioning force at the location of the fasteners  536 . Preferably, the attachment members  504  and  508  are formed from a dielectric material, so that the electrical characteristics of the reflector assembly  104  are not altered by the attachment members  504  and  508 . 
     FIG. 6 illustrates a partial cross section of an end  512  or  516  of a panel member  124 . In particular, FIG. 6 shows the end  512  or  516  of a panel member  500  wrapped around an attachment member  504  or  508 . In this way, the attachment member  504  or  508  may evenly distribute the tension applied to the panel  500  across the width of the panel  500 . The illustrated configuration also allows the face  600  of the panel  500  (corresponding to the front surface  120  of the reflector assembly  104 ), to be free from discontinuities. 
     FIG. 7 illustrates a panel member  124  in a partially folded state. Generally, the panel members  124  of a reflector assembly  104  are completely folded when the reflector assembly  104  is in a collapsed state. As the reflector assembly  104  is deployed, the panel members  120  unfold to form the reflective surface of the reflector  160 . 
     Referring now to FIG. 8, the reflector assembly  104  is partially illustrated in a front perspective view. In particular, FIG. 8 illustrates the components of the connecting assembly  128 , including the tensioning assembly  400 . Generally, the tensioning assembly  400  interconnects the end ribs  140  to the boom  132 . The tensioning assembly  400  includes a tensioning member  800  and a tensioning linkage  804 . The tensioning member  800  is biased outwardly from the boom  132 , along an axis of the boom  132 , by a spring (not shown) located within a spring housing  808 . According to one embodiment, the tensioning member  800  comprises a tensioning rod. The tensioning linkage  804  may comprise a cable fixed to an end rib fitting  812  located on the end rib  140   d  at a first end, and to the end of the tensioning member  800  at a second end. The outward bias of the tensioning member  800  causes the tensioning linkage  804  to pull the end rib  140   d  away from the companion end rib  140   c  (see FIGS.  1  and  4 ). In this way, the force introduced by the spring to the tensioning member  800  is transmitted to the associated end rib  140  by the tensioning linkage  804 . The force is then transmitted from the end rib  140  to the panel members  124 , thereby placing the panel members  124  under tension. Ultimately, the tension is carried to the end rib  140   c  (See FIG. 1) that is paired with the end rib  140   d  and that is interconnected to the boom  132 . The use of a springloaded tensioning assembly  400  allows the reflector assembly  104  to accommodate manufacturing tolerances that may result in differences between the length of the connecting assembly  128 , and the length of the panel members  124  and/or limiting members  404  when the reflector assembly  104  is deployed. Although the use of a spring-loaded tensioning assembly  400  provides certain advantages, it is not required. Additionally, the advantages of a spring-loaded tensioning assembly  400  can be realized even if such an assembly is used at only one end rib  140  in each pair of end ribs  140 . For example, in the embodiment illustrated in FIG. 3, end ribs  140   d  and  140   a  may be interconnected to tensioning assemblies  400 , while end ribs  140   b  and  140   c  may be rigidly mounted to the boom  132 . 
     FIG. 9 illustrates a portion of the reflector assembly  104  while in a deployed state. As shown in FIG. 9, the limiting members  404 , shown in FIG. 9 as catenary belts, may be positioned behind the panel members  124 , so they do not interfere with the reflective qualities of the reflector  160 . As discussed above, the limiting members  404  are affixed to the ribs  136  and  140  to limit the distance between adjacent ribs  136  and  140  when the reflector assembly  104  is deployed. As illustrated in FIGS. 4 and 9, the limiting members  404  may be aligned such that they are substantially parallel to the major axis of the boom  132  when they are in tension. Alternatively or in addition, the limiting members  404  may be affixed to ribs  136  and  140  such that they are at an angle to the boom  132  to provide additional stability to the reflector assembly  104 . For instance, the limiting members  404  may be arranged so that they form crossed pairs when the reflector assembly  104  is in a deployed state. By limiting the maximum distance between adjacent ribs  136  and  140 , the limiting members  404  may be used to control the tension introduced to the panel members  124 . Because the limiting members  404  are preferably inelastic, they also serve to control the position of the inner ribs  136  with respect to each other and to the end ribs  140 . 
     With reference now to FIG. 10, the connection between the ribs  136  and  140  and the panel members  124  is illustrated. The panel members  124  may be affixed to the ribs  136  and  140  using threaded fasteners  536  or other mechanical fastening means. Alternatively, the panel members  124  may be affixed to the ribs  136  and  140  using an adhesive. The panel members  124  are aligned such that the gaps  1000  between adjacent panel members  124  are very small. By maintaining small gaps  1000  between the panel members  124 , the efficiency of the reflector  160  may be optimized. It is preferable that the panel members  124  do not overlap, as any overlap would cause discontinuities in the front surface  120  of the reflector  160 , degrading the reflector&#39;s  160  efficiency. Preferably, the total area of the gaps  1000  between the panel members  124  is about one percent or less of the total surface area of the reflector  160 . 
     With reference now to FIG. 11, a method of forming a panel member  124  will be described. Initially, a panel  500  is cut to the desired width plus any additional material needed to form a hem along the free edges  520  and  524  of the panel  500 , if desired. The panel  500  is also cut to the desired length, plus any material needed to wrap about the attachment members  504  and  508 , and to form a hem at the ends  512  and  516  of the panel  500 , if desired. The ends  512  and  516  of the panel  500  may then be wrapped about the attachment members  504  and  508 , and affixed thereto with adhesive. Next, a first center hole  1100  is punched through the center of the panel  500  and the attachment member  504  at the first end  512  of the panel  500 . The panel  500  is then placed under a predetermined amount of tension. Generally, the amount of tension is equal to the amount of tension that the panel member  124  will be under when the complete reflector assembly  104  is deployed. While the panel  500  is held under the predetermined amount of tension, a second center hole  1104  is punched in the center of the panel  500  and through the center of the attachment member  508  at the second fixed end of the panel  500 , and at a predetermined distance from the first center hole  1000 . Finally, holes  1108  are punched in each of the four corners of the panel member  124 . The panel member  124  thus formed will have a predetermined length when the panel member  124  is placed under a predetermined amount of tension. Accordingly, the dimensions and characteristics of the deployed reflector  160  can be precisely controlled. 
     With reference again to FIGS. 3A and 3B, the antenna system  100 , including the reflector assembly  104 , may be placed in a collapsed condition, allowing the antenna system  100  to be stowed inside a relatively small volume, such as a spacecraft fairing  300 . With reference now to FIGS. 12A-E, the deployment sequence of the reflector assembly  104  will be explained. Generally, the reflector assembly  104  is initially transported to the site at which the antenna system is to be deployed. For example, the reflector assembly  104  may be transported into orbit about the Earth in the fairing  300  of a spacecraft. Upon reaching the desired location, the reflector assembly  104  may be removed from the fairing  300 . Next, the ribs  136  and  140  of the reflector assembly  104  may be opened about the hinges  304 , as is illustrated in FIGS. 12A and 12B. The ribs  136  and  140  are opened until they are fully extended, as illustrated in FIG.  12 C. When fully extended, the halves  144 ,  148 ,  152  and  156  of the ribs  136  and  140  generally form a continuous front surface or face  172  for supporting the panel members  124  in the desired geometric configuration. 
     Next, the boom  132  may be extended along its major axis to, through the tensioning assembly  800 , draw the end ribs  140  away from each other. When the boom  132  is fully extended, as illustrated in FIG. 12E, the reflector  160  of the reflector assembly  104  will have been fully deployed, and will have reached its final geometric configuration. 
     For purposes of illustration, FIGS. 12A-E omit the limiting members  404  and the feed assembly  108 , and FIGS. 12D and 12E show the panel members  124  as a continuous surface. Generally, the panels  500  of the panel members  124  are in a folded condition when the reflector assembly  104  is folded as illustrated in FIGS. 3A,  3 B and  12 A-C. Likewise, the limiting members  404  are also folded when the reflector assembly  104  is in a collapsed state. When the reflector assembly  104  is fully deployed, as illustrated in FIGS. 1,  4  and  12 E, the tensioning assembly  800  exerts a force on each associated end rib  140  which pulls those end ribs away from the end rib  140  with which they are paired. The distance between adjacent ribs  136  and  140  is limited by the limiting members  404 . Accordingly, the panel members  124  are held under a predetermined amount of tension between the ribs  136  and  140  to which the panel members  124  are affixed. As the panel members  124  do not overlap, and as the gaps  1000  between adjacent panel members  124  are small, a highly efficient reflector  160  is formed when the reflector assembly  104  is deployed. 
     In accordance with the present invention, a deployable reflector for an electronically scanned reflector antenna is provided. The invention in its broader aspects relates to a reflector antenna system that can be placed in a very small volume for transportation to a deployment site, and that forms a relatively large reflector surface upon deployment. The deployable reflector of the present invention is suitable for use with any antenna requiring a large reflector. The reflector of the present invention can be assembled at relatively low cost to provide a highly accurate reflector surface. 
     The foregoing discussion of the invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modification commensurate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain the best mode presently known of practicing the invention, and to enable others skilled in the art to utilize the invention in such or in other embodiment and with various modifications required by their particular application or use of the invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.