Truss type folding and unfolding structure, truss type antenna and antenna building method

Abstract

The invention discloses a truss type folding and unfolding structure, a truss type antenna and an antenna building method, and belongs to the field of spaceflight. The invention aims to solve the problem of how to not only meet the requirement of large aperture, but also accommodate an antenna in a limited space. The device comprises an annular truss, a center driving mechanism and inhaul cables. The annular truss is provided with an energy storage element used for supporting the annular truss to be opened. The center driving mechanism is provided with two take-up and pay-off assemblies symmetrically arranged on the upper side and the lower side of the annular truss. The number of the inhaul cables is multiple, each hinge point of the annular truss corresponds to one inhaul cable and is connected with the corresponding inhaul cable, the inhaul cables at the two adjacent hinge points are alternately arranged on the upper side and the lower side of the annular truss, and the two inhaul cables are connected with the upper take-up and pay-off assembly and the lower take-up and pay-off assembly correspondingly so that the annular truss can be folded and tightened. When the truss type folding and unfolding structure is in a folding state, the two take-up and pay-off assemblies synchronously release the inhaul cables, and the energy storage element releases stored energy so as to support the annular truss to be unfolded.

Description

Technical Field

[0001] The present invention belongs to the field of aerospace, and in particular relates to a truss-type retractable structure, a truss-type antenna and an antenna construction method. Background Art

[0002] With the continued advancement of space exploration and the rapid development of communication technology, especially the increasing demand for satellite communications and space observation missions, the need for large-aperture antennas has become increasingly urgent. The aperture and gain of an antenna directly determine the accuracy of space communications and observations. Therefore, the application of large-aperture antennas in space missions is particularly important. However, due to the limited launch space and payload constraints of spacecraft, designing an antenna that can both meet the large aperture requirements and be accommodated within this limited space has become a key issue in technological development. Summary of the Invention

[0003] In view of this, the present invention provides a truss-type retractable structure, a truss-type antenna and an antenna construction method, which can be folded and tightened during transportation and unfolded when reaching the target location to form a large-diameter antenna.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A truss-type retractable structure, comprising:

[0006] The ring truss is provided with an energy storage element for supporting the expansion of the ring truss;

[0007] The central drive mechanism is provided with two retractable wire assemblies, which are symmetrically arranged on the upper and lower sides of the center of the annular truss;

[0008] There are multiple cables, each hinge point of the annular truss corresponds to a cable, and the cables at two adjacent hinge points are alternately arranged on the upper and lower sides of the annular truss, and the two adjacent cables correspond to the upper and lower retractable wire assemblies respectively. One end of each cable is connected to the hinge point of the corresponding annular truss, and the other end is retracted to the corresponding retractable wire assembly, so that the annular truss is folded and tightened;

[0009] When the truss-type retractable structure is in a retracted state, the two retractable wire assemblies release the cables synchronously, and the energy storage element releases the stored energy to support the expansion of the annular truss.

[0010] Furthermore, the annular truss includes 2N supporting links connected end to end and a hinge connecting piece connecting two adjacent supporting links, N≥2, and the supporting links are rotatably connected to the hinge connecting piece via a pin.

[0011] Furthermore, the energy storage element is a torsion spring, which is sleeved on the pin shaft, one leg of the torsion spring is connected to the hinge connector, and the other leg is connected to the end of the supporting connecting rod.

[0012] Furthermore, each retractable wire assembly includes a fixed base plate, a slide plate, a first pulley and a second pulley. The fixed base plate and the slide plate are coaxially arranged on the side of the annular truss. The slide plate is located between the fixed base plate and the annular truss and can move along the axis of the annular truss. There are N first pulleys and N second pulleys. The N first pulleys are evenly arranged on the fixed base plate along the circumferential direction of the fixed base plate, and the N second pulleys are evenly arranged on the slide plate along the circumferential direction of the slide plate. One end of the cable is fixed to the fixed base plate, and the other end passes through the second pulley and the first pulley in sequence and is connected to the hinge point of the annular truss.

[0013] Furthermore, the central driving mechanism also includes a synchronous driving component, which can drive the two slides to move synchronously and symmetrically.

[0014] Furthermore, the synchronous drive assembly includes a double helical screw, a screw nut and a guide rod. The double helical screw is coaxially connected to two fixed base plates, the guide rod is connected to the two fixed base plates, and there are two screw nuts. Each slide corresponds to a screw nut and is fixedly connected to the corresponding screw nut. The two slides are respectively screwed to the two sections of the studs of the double helical screw through the corresponding screw nuts, and each slide is slidably connected to the guide rod.

[0015] Furthermore, the inner diameter of the annular truss after unfolding is greater than 1 m.

[0016] Furthermore, the annular truss is a hexagonal truss.

[0017] Another technical solution adopted in the present invention is:

[0018] A truss antenna comprises an antenna and a truss retractable structure. One end of the antenna is connected to the annular truss, and the other end is connected to a fixed bottom plate.

[0019] Another technical solution adopted in the present invention is:

[0020] A method for constructing a truss antenna is implemented using a truss antenna. The construction process is as follows:

[0021] S1, the rocket transports the retracted truss antenna structure to the target location;

[0022] S2, the double helical screw rotates, and the two screw nuts drive the slides connected to them to move toward the fixed base plate, and the cable is gradually released;

[0023] S3, the torsion spring at the end of each supporting link releases the stored elastic force, and the torsion spring drives the supporting link to rotate from vertical to horizontal, the annular truss is unfolded, and the antenna is straightened;

[0024] S4, the double helical screw stops rotating, and the antenna structure is now completed.

[0025] The beneficial effects of the present invention compared with the prior art are:

[0026] 1. The cables of the present invention are divided into two groups, one located above the annular truss and the other located below it. Each group of cables is driven to retract or release by a retractable cable assembly. When the cables are retracted to the retractable cable assembly, the two groups of cables exert an upward pulling force on some of the alternating hinge points of the annular truss, and a downward pulling force on other alternating hinge points. Under these two pulling forces, the annular truss folds and gathers inward, thereby achieving the folding and tightening of the annular truss. When the truss-type retractable structure needs to be deployed, the two retractable cable assemblies simultaneously release the cables, the annular truss is no longer constrained, and the energy storage element releases the stored energy and drives the annular truss to expand, thereby achieving the deployment of the truss-type retractable structure. The cooperation of the cables and the retractable cable assembly allows the annular truss to fold and tighten, reducing its overall volume. The inner diameter of the annular truss after deployment can be greater than 1 meter. Therefore, this truss-type retractable structure can be used to manufacture large-diameter antennas. The antenna can be tightened during rocket transportation into space, reducing its transport size. When the antenna is transported to the target location, it can be unfolded to achieve high-caliber, high-gain antenna functions.

[0027] 2. The supporting connecting rods of the present invention are made of carbon fiber rods with relatively light weight and high strength, which not only reduces the weight of the entire truss-type retractable structure and facilitates spatial transportation, but also has relatively high strength and rigidity, thereby increasing the bearing capacity of the truss-type retractable structure.

[0028] 3. The ring truss of the present invention is supported by three cables suspended from above, and the double-helical screw and nut feature a self-locking mechanism. This allows the ring truss to support the antenna and maintain balance even without external forces, resulting in strong stability. Furthermore, the design of the double-helical screw, screw nut, fixed base plate, and slide plate not only allows for simultaneous winding and payout of the upper and lower cable groups, but also allows for simultaneous winding and payout of multiple cables within each group, ensuring synchronization of all cables. The drive motor is solely for the double-helical screw, resulting in a simple overall structure, easy operation, and guaranteed precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are incorporated in and constitute a part of this application and are used to provide a further understanding of the present invention.

[0030] Figure 1 It is a structural schematic diagram of a truss-type retractable structure of the present invention.

[0031] Figure 2 for Figure 1 A partial enlarged view of point A in the middle.

[0032] Figure 3Schematic diagram of the three-dimensional structure of the retractable wire assembly.

[0033] Figure 4 It is a side view of the retractable wire assembly.

[0034] Description of reference numerals:

[0035] 1- Base;

[0036] 2-annular truss, 21-energy storage element, 22-support connecting rod, 221-first hinge connection seat, 23-hinge connection member, 231-draw hook, 232-second hinge connection seat;

[0037] 3-retracting and releasing wire assembly, 31-fixed bottom plate, 32-slide plate, 33-first pulley, 34-second pulley;

[0038] 4-synchronous drive assembly, 41-double helical screw, 42-screw nut, 43-guide rod;

[0039] 5- Cable. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example 1:

[0042] Figure 1 FIG1 shows a structural diagram of a truss-type retractable structure of this embodiment. Figure 1 , a truss-type retractable and deployable structure of this embodiment includes a base 1, an annular truss 2, a central drive mechanism and a cable 5. The base 1 has a supporting function, the central drive mechanism is installed on the base 1, the annular truss 2 is sleeved outside the central drive mechanism, and the annular truss 2 is provided with an energy storage element 21 for supporting the opening of the annular truss 2. The central drive mechanism is provided with two retractable wire assemblies 3, and the two retractable wire assemblies 3 are symmetrically arranged on the upper and lower sides of the center of the annular truss 2; there are multiple cables 5, each hinge point of the annular truss 2 corresponds to a cable 5, and the cables 5 at the two adjacent hinge points are alternately arranged on the upper and lower sides of the annular truss 2, and the two adjacent cables 5 correspond to the upper and lower retractable wire assemblies 3 respectively, one end of each cable 5 is connected to the corresponding hinge point of the annular truss 2, and the other end extends obliquely to the corresponding retractable wire assembly 3, and is retracted by the retractable wire assembly 3. Combined with Figure 1 It can be seen that the cables 5 are actually divided into two groups, one group is located above the annular truss 2, and the other group is located below the annular truss 2. When the cables 5 are retracted to the retractable wire assembly 3, the two groups of cables 5 generate an oblique upward pulling force on some of the alternately arranged hinge points of the annular truss 2, and other alternately arranged hinge points generate an oblique downward pulling force. The annular truss 2 can be folded and gathered inward under these two pulling forces, thereby realizing the folding and tightening of the annular truss 2.

[0043] When the truss-type retractable structure needs to be unfolded, the two retractable wire assemblies 3 simultaneously release the cables 5, the annular truss 2 is no longer constrained, the energy storage element 21 releases the stored energy and drives the annular truss 2 to open, thereby realizing the unfolding of the truss-type retractable structure. When the truss-type retractable structure needs to be folded and tightened, the multiple cables 5 are retracted by the two retractable wire assemblies 3. Under the tension of the cables 5, the annular truss 2 overcomes the driving force of the energy storage element 21 and is in a contracted and folded state as a whole. The energy storage element 21 stores energy, and at the same time, the truss-type retractable structure realizes folding and contraction. It can be clearly seen that the annular truss 2 can be folded and tightened with the cooperation of the cables 5 and the retractable wire assemblies 3, reducing the overall volume. The inner diameter of the annular truss 2 after unfolding can be greater than 1m, so this truss-type retractable structure can be used to make large-caliber antennas. The antenna can be tightened during transportation to space by a rocket to reduce the transportation size. When the antenna is transported to the target location, the antenna can be unfolded, thereby realizing the antenna function of high caliber and high gain.

[0044] Combine Figure 1 The annular truss 2 of this embodiment further includes 2N supporting links 22 connected end to end and a hinged connection 23 connecting two adjacent supporting links 22. The annular truss 2 is preferably a hexagonal truss, that is, the supporting links 22 are preferably six, and the supporting links 22 are made of carbon fiber rods with relatively light weight and high strength. This not only reduces the weight of the entire truss-type retractable structure and facilitates space transportation, but also has high strength and rigidity, increasing the load-bearing capacity of the truss-type retractable structure. Figure 2 , a first hinge connection seat 221 is provided at each end of the supporting link 22 for connecting the hinge connection member 23. Figure 1 and Figure 2 There are six hinge connectors 23, each hinge connector 23 is provided with a hook 231, and the cable 5 is connected to the hook 231 of the hinge connector 23. A second hinge seat 232 is provided at each end of each hinge connector 23, and the support link 22 and the hinge connector 23 are rotatably connected through the cooperation of the first hinge seat 221, the second hinge seat 232 and the pin. It should be noted that the pin is horizontally inserted on the first hinge seat 221 and the second hinge seat 232, so that the support link 22 rotates up and down when rotating around the pin, that is, the two ends of the support link 22 have the freedom to rotate up and down, so that the support link 22 can be rotated from a horizontal state to a vertical state under the tension of the cable 5, and the six support links 22 are tightened and closed together, thereby reducing the overall volume of the annular truss 2. Specifically, combined with Figure 1When the two retractable and retractable wire assemblies 3 are retracted at the same time, the group of cables 5 above the annular truss 2 generates an upward pulling force along the length direction of the cables 5 on each hinged connection 23 connected thereto, and the group of cables 5 below the annular truss 2 generates a downward pulling force along the length direction of the cables 5 on each hinged connection 23 connected thereto. Figure 4 , the tension F of the cable 5 is decomposed into a horizontal inward tension F1 and a vertical downward / vertically upward tension F2. The tension F is transmitted to the ends of the two adjacent support links 22 via the hinge connection 23. Since the two adjacent cables 5 are arranged alternately up and down, the vertical forces exerted on the two adjacent hinge connections 23 are exactly opposite. The two ends of each support link 22 are respectively subjected to vertical upward and vertical downward tension. The support link 22 is subjected to unbalanced force and rotates relative to the connected hinge connection 23; at the same time, the two ends of each support link 22 are also subjected to inward tension, so the support link 22 will move inward while rotating. In addition, one end of the two adjacent support links 22 is connected by a hinge connection 23. Then, when the cable 5 generates tension on the two adjacent support links 22, the one end of the two support links 22 is simultaneously upward or downward, thereby realizing the bending between the two adjacent support links 22. The maximum bending angle between the support link 22 and the hinge connection is 90°. In this way, the two adjacent support links 22 are parallel when bent to the maximum angle, which can ensure that the volume of the annular truss 2 is minimized when it is fully gathered.

[0045] In addition, combined Figure 2 Each hinge connection member 23 is a bent integral member with a bending angle of 120°. In this way, when the annular truss 2 is unfolded, the angle between two adjacent supporting links 22 in the horizontal direction is 120°.

[0046] In this embodiment, the energy storage element 21 is preferably a torsion spring, which is mounted on a pin. One leg of the torsion spring is connected to the hinge connector 23, and the other leg is connected to the end of the support link 22. When the annular truss 2 is in a collapsed or folded state, the two adjacent support links 22 are parallel, and the torsion spring is bent, thereby storing elastic potential energy. When the cable 5 releases the annular truss 2, the support links 22 and the hinge connector are no longer constrained. The torsion spring releases its elastic potential energy and drives the support links 22 and the hinge connector 23 to reset, thereby achieving the expansion of the annular truss 2.

[0047] Figure 1 The schematic diagram of the central drive mechanism is shown. Figure 1The central driving mechanism of this embodiment includes a synchronous drive component 4 and two retractable wire components 3. The synchronous drive component 4 coaxially passes through the annular truss 2. The two retractable wire components 3 are symmetrically installed on the synchronous drive component 4, and are driven by the synchronous drive component 4 to synchronously retract or synchronously pay out.

[0048] Combine Figure 3 and Figure 4 In this embodiment, each retractable wire assembly 3 includes a fixed base plate 31, a slide plate 32, a first pulley 33 and a second pulley 34. The fixed base plate 31 and the slide plate 32 are coaxially arranged on the side of the annular truss 2 and supported by the synchronous drive assembly 4. The fixed base plate 31 in the retractable wire assembly 3 below is fixed on the base 1 and remains stationary. The slide plate 32 is between the fixed base plate 31 and the annular truss 2 and can move along the axis of the annular truss 2. The first pulley 33 and the second pulley 34 are both There are three first pulleys 33 evenly mounted on the fixed base plate 31 along its circumference, and three second pulleys 34 evenly mounted on the slide plate 32 along its circumference. Each cable 5 has one end fixed to the fixed base plate 31, and the other end extends toward the slide plate 32, passing around the second pulley 34, then toward the fixed base plate 31, passing around the first pulley 33, and finally toward the hinged connection 23 of the annular truss 2, connecting to the hook 231 of the hinged connection 23. As can be seen, a portion of the cable 5 is retracted between the first pulley 33 and the second pulley 34, and the retracted length of the cable 5 can be adjusted by adjusting the distance between the first pulley 33 and the second pulley 34.

[0049] Combine Figure 1 The synchronous drive assembly 4 of this embodiment includes a double-helical screw 41, a screw nut 42, and a guide rod 43. The double-helical screw 41 has two threaded sections with opposite spiral directions. One end of the double-helical screw 41 is rotatably mounted on one of the fixed base plates 31, and the other end coaxially passes through the annular truss 2 and is rotatably mounted on the other fixed base plate 31. Three guide rods 43 are provided, and these three guide rods 43 are evenly arranged around the double-helical screw 41. The two ends of each guide rod 43 are respectively fixed to the two fixed base plates 31. Two screw nuts 42 are provided, and each slide plate 32 corresponds to a screw nut 42 and is fixedly connected to the corresponding screw nut 42. The two slide plates 32 are respectively screwed to the two threaded sections of the double-helical screw 41 via the corresponding screw nuts 42, and each slide plate 32 is slidably connected to the guide rod 43.

[0050] When the annular truss 2 is in the folded and retracted state, the distance between the slides 32 in the upper and lower retractable wire assemblies 3 is minimal. The double-helical screw 41 can be driven to rotate by a motor, and the screw nut 42 moves along the axis of the double-helical screw 41 toward the fixed base plate 31. At this time, the distance between the slide 32 and the fixed base plate 31 decreases, and at the same time, the cable 5 between them relaxes, that is, the cable 5 no longer exerts a pulling force on the hinge connection 23 and the support link 22. The cable 5 is pulled out under the restoring force of the torsion spring, and the support link 22 gradually resets to the hinge connection 23. Because the screw is a double-helical screw 41, the two slides 32 move in opposite directions at the same time, so that the cables 5 arranged alternately above and below can be released synchronously. The forces at both ends of each support link 22 are equal, and the flipping forces of the upper and lower rotations are opposite in direction. The support link 22 gradually rotates from a vertical state to a horizontal state, thereby realizing the expansion of the annular truss 2. When the annular truss 2 needs to be folded and tightened, the double-helical screw 41 rotates in the reverse direction, and the screw nut 42 moves along the axis of the double-helical screw 41 away from the fixed base plate 31. At this time, the distance between the slide 32 and the fixed base plate 31 gradually increases, and the cable 5 is retracted between the slide 32 and the fixed base plate 31. The cable 5 exerts a pulling force on the hinge connection 23, thereby achieving the folding and tightening of the annular truss 2.

[0051] It should be noted that, after deployment, the annular truss 2 is supported by the three cables 5 above it. The double helical screw 41 and its nut feature a self-locking mechanism, allowing the annular truss 2 to maintain balance and stability even without external forces. Furthermore, the design of the double helical screw 41, screw nut 42, fixed base plate 31, and slide plate 32 not only allows for simultaneous winding or unwinding of the upper and lower groups of cables 5, but also allows for simultaneous winding or unwinding of multiple cables 5 within each group, ensuring synchronization of all cables 5. Furthermore, the drive motor is solely for the double helical screw 41, resulting in a simple overall structure and convenient operation, ensuring precise operation.

[0052] Example 2:

[0053] A truss antenna in this embodiment includes an antenna and a truss-type retractable structure as described above. Multiple antennas are arranged along the circumferential direction of the annular truss 2. One end of each antenna is connected to the annular truss 2, and the other end is connected to the fixed base plate 31 above.

[0054] Example 3:

[0055] A method for constructing a truss antenna in this embodiment is implemented using the truss antenna described above. The construction process is as follows:

[0056] S1, the rocket transports the retracted truss antenna structure to the target location;

[0057] S2, when the target position is reached, the motor drives the double-helical screw 41 to rotate, and the two screw nuts 42 respectively drive the slides 32 connected to them to move toward the fixed base plate 31. The distance between the slides 32 and the fixed base plate 31 gradually decreases. At the same time, the cable 5 between the two relaxes, that is, the cable 5 no longer exerts a pulling force on the hinge connector 23 and the support link 22.

[0058] In step S3, the torsion spring at the end of each supporting link 22 releases the stored elastic force. The forces at both ends of each supporting link 22 are equal in magnitude, and the flipping forces of the up and down rotations are opposite in direction. The supporting link 22 gradually rotates from a vertical state to a horizontal state. At the same time, the supporting link 22 moves outward under the restoring force of the torsion spring, the annular truss 2 gradually unfolds, and the antenna is straightened.

[0059] S4, the double helical screw 41 stops rotating, and the antenna structure is now completed.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A truss-type retractable structure, characterized in that: include: The ring truss is provided with an energy storage element for supporting the expansion of the ring truss; The central drive mechanism is provided with two retractable wire assemblies, which are symmetrically arranged on the upper and lower sides of the center of the annular truss; There are multiple cables, each hinge point of the annular truss corresponds to a cable, and the cables at two adjacent hinge points are alternately arranged on the upper and lower sides of the annular truss, and the two adjacent cables correspond to the upper and lower retractable wire assemblies respectively. One end of each cable is connected to the hinge point of the corresponding annular truss, and the other end is retracted to the corresponding retractable wire assembly, so that the annular truss is folded and tightened; When the truss-type retractable structure is in a retracted state, the two retractable wire assemblies release the cables synchronously, and the energy storage element releases the stored energy to support the expansion of the annular truss.

2. The truss-type retractable structure according to claim 1, characterized in that: The annular truss includes 2N supporting links connected end to end and a hinge connecting piece connecting two adjacent supporting links, N≥2, and the supporting links are rotatably connected to the hinge connecting piece through a pin shaft.

3. The truss-type retractable structure according to claim 2, characterized in that: The energy storage element is a torsion spring, which is sleeved on the pin shaft. One leg of the torsion spring is connected to the hinge connector, and the other leg is connected to the end of the supporting connecting rod.

4. The truss-type retractable structure according to claim 1, characterized in that: Each retractable wire assembly includes a fixed base plate, a slide plate, a first pulley and a second pulley. The fixed base plate and the slide plate are coaxially arranged on the side of the annular truss. The slide plate is located between the fixed base plate and the annular truss and can move along the axis of the annular truss. There are N first pulleys and N second pulleys. The N first pulleys are evenly arranged on the fixed base plate along the circumferential direction of the fixed base plate. The N second pulleys are evenly arranged on the slide plate along the circumferential direction of the slide plate. One end of the cable is fixed to the fixed base plate, and the other end is connected to the hinge point of the annular truss after passing through the second pulley and the first pulley in sequence.

5. The truss-type retractable structure according to claim 4, characterized in that: The central driving mechanism also includes a synchronous driving component, which can drive the two slides to move synchronously and symmetrically.

6. The truss-type retractable structure according to claim 5, characterized in that: The synchronous drive assembly includes a double helical screw, a screw nut and a guide rod. The double helical screw is coaxially connected to two fixed base plates, the guide rod is connected to the two fixed base plates, there are two screw nuts, each slide corresponds to a screw nut and is fixedly connected to the corresponding screw nut, the two slides are respectively screwed to the two studs of the double helical screw through the corresponding screw nuts, and each slide is slidably connected to the guide rod.

7. The truss-type retractable structure according to claim 1, characterized in that: The inner diameter of the ring truss after unfolding is greater than 1m.

8. The truss-type retractable structure according to claim 1, characterized in that: The ring truss is a hexagonal truss.

9. A truss antenna, characterized in that: The invention comprises an antenna and a truss-type retractable structure as claimed in any one of claims 6 to 8, wherein one end of the antenna is connected to the annular truss, and the other end is connected to a fixed base plate.

10. A method for constructing a truss antenna, characterized in that: The truss antenna according to claim 9 is used for implementation, and the construction process is as follows: S1, the rocket transports the retracted truss antenna structure to the target location; S2, the double helical screw rotates, and the two screw nuts drive the slides connected to them to move toward the fixed base plate, and the cable is gradually released; S3, the torsion spring at the end of each supporting link releases the stored elastic force, and the torsion spring drives the supporting link to rotate from vertical to horizontal, the annular truss is unfolded, and the antenna is straightened; S4, the double helical screw stops rotating, and the antenna structure is now completed.

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