An antenna deployment joint

Abstract

The application relates to a retractable joint for an antenna and belongs to the technical field of antennas. The application comprises a middle support and two connecting supports, the two ends of the middle support are connected with the corresponding connecting supports through bearings; each connecting support is provided with upper and lower groups of spring connecting heads, the two upper groups of spring connecting heads opposite to each other are connected through SMA spring a, the two lower groups of spring connecting heads opposite to each other are connected through SMA spring b, and the SMA spring a and the SMA spring b are located above and below the middle support respectively. The novel shape memory alloy material is used for retraction, and the logarithmic-periodic antenna is more compact and portable.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, specifically to a retraction / extension joint for antennas. Background Technology

[0002] Currently, log-periodic antennas are often used in a new reconnaissance and early warning method that combines a ground-based vehicle with a multi-rotor drone. The ground-based vehicle arrives at the designated location, the antenna is fixed on the multi-rotor drone, the multi-rotor drone carries the antenna into the air, and the antenna is connected to the communication terminal of the ground-based vehicle through a cable for direct signal transmission. The antenna starts working when the multi-rotor drone reaches a suitable altitude.

[0003] However, traditional log-periodic antennas in the same frequency band have certain drawbacks: when the antenna operates at a frequency of 27-110Hz, the antenna is about 5 meters long, which is heavy and consumes a lot of energy; and the folding action of commonly used log-periodic antennas is mainly achieved by motors, which is not convenient for drones to carry. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings and deficiencies of the prior art by providing a retractable joint for antennas. This joint uses a novel shape memory alloy material for retraction and retraction, enabling log-periodic antennas to be more compact and portable.

[0005] This invention is achieved through the following technical solution:

[0006] An antenna extension / retraction joint includes a central support and two connecting seats. Both ends of the central support are connected to the corresponding connecting seats via bearings. Each connecting seat is provided with upper and lower sets of spring connectors. The two upper sets of spring connectors facing each other are connected by SMA spring a, and the two lower sets of spring connectors facing each other are connected by SMA spring b. SMA spring a and SMA spring b are located above and below the central support, respectively.

[0007] Furthermore, the extension directions of the SMA spring a and SMA spring b are parallel to each other, and there are two of each.

[0008] Furthermore, one end of the spring connector is connected to an SMA spring, and the other end is hinged to the connector seat it is located in.

[0009] Furthermore, the intermediate support is provided with two miniature electromagnetic locks; the support platform of the connecting seat is provided with locking holes; the miniature electromagnetic locks are aligned with the support platform on their outer side; in the locked state, the lock cylinder of the miniature electromagnetic lock passes through the outer wall of the intermediate support and is located in the corresponding locking hole.

[0010] Furthermore, the inner side of the connecting seat has a support platform; the extended connecting end of the intermediate support and the support platform are located on both sides of the bearing, and are connected to the bearing.

[0011] Furthermore, the intermediate support includes a support body and a support cover plate; the support cover plate is fastened to the support body and forms a sealed space; the miniature electromagnetic locks are all located within the sealed space; the outer side of the support body is provided with an extension connection end integrated with it.

[0012] Each support platform has bearings on both sides, for a total of four bearings;

[0013] The outer sides of the bearings on both sides of the support platform are the end of the support cover plate and the extension connection end, respectively.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This device employs a novel shape memory alloy material for its retractable key design, enabling the design and manufacture of an ultralight, novel retractable log-periodic antenna structure that is 1 to 2 orders of magnitude lighter than current retractable log-periodic antennas in the same frequency band. Attached Figure Description

[0016] Figure 1 This is an overall structural diagram of an embodiment of the present invention;

[0017] Figure 2 yes Figure 1 Schematic diagram of a cover plate without support;

[0018] Figure 3 This is a diagram of the joint unlocking structure during the antenna folding process according to an embodiment of the present invention;

[0019] Figure 4 This is a diagram of the joint structure of the antenna in the folded state according to an embodiment of the present invention;

[0020] Figure 5 This is a diagram of the joint structure during the antenna deployment process according to an embodiment of the present invention;

[0021] Figure 6 This is a diagram of the joint locking mechanism during the antenna deployment process according to an embodiment of the present invention;

[0022] Figure 7 This is an exploded view of the structure of an embodiment of the present invention.

[0023] Figure 8 This is a structural diagram showing the fit between the support base and the bearing in an embodiment of the present invention.

[0024] Figure 9 This is a schematic diagram illustrating the antagonistic interaction principle of two SMA elements.

[0025] In the figure: 27-1, support cover plate; 27-2, connecting seat; 27-3, spring connector; 27-4, SMA spring a; 27-5, SMA spring b; 27-6, miniature electromagnetic lock; 27-7, bearing; 27-8, support body; 27-9, extension connection end; 27-10, locking hole. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] This invention uses invertebrate reptiles that crawl as biomimetic objects. By utilizing their Ω-shaped movement pattern during crawling, and employing the design concepts of morphology and functional bionics, a biomimetic mechanism concept configuration is proposed. This avoids the need for a large number of servo mechanisms in traditional mechanisms and is very suitable for miniaturized environments.

[0028] Antagonistic (mutually driven) SMA actuators consist of two sets of SMA actuators that work in opposition to each other. The basic principle can be described as follows: driving the first set of SMA actuators causes an austenitic transformation, while the second set, at room temperature, passively undergoes a non-twinned martensitic transformation. During cooling, the first set of SMA actuators undergoes a martensitic transformation, subsequently driving the second set, which then undergoes an austenitic transformation. The cooled first set of SMA actuators then passively undergoes a non-twinned martensitic transformation.

[0029] Reference Figure 9 This paper describes the antagonistic interaction principle of two SMA elements. From a macroscopic mechanical perspective, the phase transformation of SMA from martensite to austenite can be viewed as an increase in structural stiffness. Specifically, SMA spring a exhibits hyperelasticity in high-temperature austenitic conditions, with an approximately linear force-deformation curve; however, at low temperatures, it exhibits nonlinear behavior due to the non-twinned transformation of martensite. Figure 8In the given force-deformation plane, the horizontal axis represents the amount of structural deformation. For SMA spring a, this deformation is characterized by its axial length (denoted as X1), increasing from left to right (i.e., the spring length increases). For SMA spring b, the structural deformation is represented by the axial length (denoted as X2), increasing from right to left (this definition is primarily for consistency in describing these two types of deformation). The left and right vertical axes represent the deformation forces of SMA spring a and SMA spring b, respectively. The subscripts A and M denote the austenitic and martensitic phases, respectively. For example, PM represents the force on spring a in the martensitic state. R1 is the unloading force on spring a in the martensitic state, and R2 is the unloading force on spring b in the martensitic state. The slope at any point represents the stiffness of the structure under the corresponding deformation.

[0030] The principle of SMA element antagonism is described as follows: At the initial point O, both springs a and b are martensitic and in a state of force equilibrium, which is the first step of joint gait. Let the initial length of springs a and b be X0. First, spring a is energized and, due to the memory effect, contracts into an austenitic shape, pulling spring b to further elongate. This process can be illustrated by the OA path, in which the new equilibrium point (point A) migrates from the martensitic state of spring a to the austenitic state along the martensitic stiffness curve of spring b. The OA path is the second step of joint gait. Then, spring a cools down, its stiffness decreases, and thus the tension decreases, making the elastic restoring force of spring b dominant, driving the two structures to recover. However, due to the hysteresis effect, the recovery path (AB) does not coincide with the martensitic loading curve of spring b, but is parallel to the martensitic unloading curve of spring b. Point B is another equilibrium state of the two SMA elements in martensite, which does not coincide with point O. Then, spring b acts as the driving element. Heating increases its stiffness, and spring b will contract to a preset austenitic shape, at which point the evolution path is BC. The ABC path is the third step of the joint gait. Finally, spring b cools down, its stiffness decreases, and the elastic restoring force of spring a becomes dominant. Similarly, due to the hysteresis effect, the recovery path (CD) does not coincide with the martensitic loading curve of spring a, but is parallel to the direction of the martensitic unloading curve of spring a. This is the process of structural reset. This completes a full driving cycle, and point D becomes the new starting point of the next cycle. Due to the inherent hysteresis behavior of SMA, points B and D are relatively close, but do not coincide with the initial point O. Such an ∞-shaped curve means that the input electrothermal energy cannot be completely converted into effective functional deformation of the joint. The regions enclosed by "DA-XA-XD" and "BC-XC-XB" represent the external work input to spring a and spring b during the stable cycle, respectively. Their overlapping part, the pentagon "OB-XB-XD-D", is used to eliminate the effect of material hysteresis and promote system reset. Obviously, the smaller the area of ​​this region, the higher the driving efficiency.

[0031] Reference Figure 1 , Figure 7 and Figure 8 The structural diagram shows that this embodiment includes an intermediate support and two connecting seats. Both ends of the intermediate support are connected to the corresponding connecting seats through bearings. Each connecting seat is provided with upper and lower sets of spring connecting heads. The two upper sets of spring connecting heads facing each other are connected by SMA spring a, and the two lower sets of spring connecting heads facing each other are connected by SMA spring b. SMA spring a and SMA spring b are located above and below the intermediate support, respectively.

[0032] The SMA springs a and b extend in parallel directions, and each has two springs.

[0033] One end of the spring connector is connected to an SMA spring, and the other end is hinged to the connector seat it is located in.

[0034] The intermediate support is equipped with two miniature electromagnetic locks; the support platform of the connecting seat is provided with locking holes; the miniature electromagnetic locks are directly opposite the support platform on their outer side; in the locked state, the lock cylinder of the miniature electromagnetic lock passes through the outer wall of the intermediate support and is located in the corresponding locking hole.

[0035] The inner side of the connecting seat has a support platform; the extended connecting end of the intermediate support and the support platform are located on both sides of the bearing, and are connected to the bearing.

[0036] The intermediate support includes a support body and a support cover plate; the support cover plate is fastened to the support body and forms a sealed space; the miniature electromagnetic locks are all located within the sealed space; the outer side of the support body is provided with an extension connection end integrated with it.

[0037] Each support platform has bearings on both sides, for a total of four bearings;

[0038] The outer sides of the bearings on both sides of the support platform are the end of the support cover plate and the extension connection end, respectively.

[0039] The specific steps of the retraction and extension process described in this embodiment can be summarized as follows:

[0040] Initial state as Figure 2 As shown, the miniature electromagnetic lock is in a de-energized state and the joint is in a locked state; at the same time, SMA spring a and SMA spring b are in a force balance state.

[0041] The first step involves the miniature electromagnetic lock cylinder retracting via circuit control, thus fulfilling the unlocking condition. Figure 3 As shown.

[0042] The second step involves heating the SMA spring b. Spring b returns to its initial state, the overall structure contracts, and the SMA spring a is stretched, bringing it to a low-temperature martensitic state. Simultaneously, the miniature electromagnetic lock circuit disconnects, and the lock cylinder springs back. (Example:) Figure 4 As shown.

[0043] The third step involves energizing the miniature electromagnetic lock, causing the lock cylinder to retract and meet the unlocking conditions; heating the SMA spring a, which returns to its initial state, causing the overall structure to unfold again, and stretching the SMA spring b, which then enters a low-temperature martensitic state. Figure 5 As shown.

[0044] Fourthly, the miniature electromagnetic lock is de-energized, the lock cylinder pops out, the locking structure resets, and the overall structure is re-locked. For example... Figure 6 As shown.

[0045] This completes one cycle of opening and closing.

[0046] The above design provides the basic architecture for the functional realization of ultra-lightweight large-scale circumferential antennas. In principle, the antagonistic SMA driven joint requires only one driving element. For example, with SMA spring a as the active element, SMA spring b acts as the driven element. When spring a is energized, it contracts, stretching the structure of spring b. Subsequently, SMA spring a dissipates heat, and the low-temperature martensite generated during the stretching process of spring b will drive the joint back to its original state (since the stiffness of austenite is significantly greater than that of martensite, the tension of SMA spring a will be greatly reduced during heat dissipation). After the structure closes, this project uses an antagonistic mutual drive mechanism to solve the deployment problem. At this time, with SMA spring b as the active element, SMA spring a acts as the driven element. When SMA spring b is energized, it generates a contraction driving force, expanding the structure of spring a. Subsequently, SMA spring b dissipates heat, and the structure of spring a returns to its initial low-temperature martensite state.

[0047] In the antagonistic SMA drive joint, both SMA components—spring a and spring b—serve as drive elements, alternately acting as the active element to drive the other. This not only achieves the desired functional deformation but also shortens their respective slow cooling phases. Furthermore, the controllability of the structure is significantly improved. We can precisely control the excitation and cooling phases of the SMA structure by setting excitation currents of different magnitudes and durations.

[0048] It should be noted that the above description is merely a preferred application example of the present invention and is not intended to limit the scope of protection of the present invention. All technical solutions employing equivalent substitutions or equivalent transformations are within the scope of protection of the present invention.

Claims

1. A retractable joint for an antenna, characterized in that, It includes an intermediate support and two connecting seats. Both ends of the intermediate support are connected to the corresponding connecting seats via bearings. Each connecting seat is provided with upper and lower sets of spring connecting heads. The two upper sets of spring connecting heads facing each other are connected by SMA spring a, and the two lower sets of spring connecting heads facing each other are connected by SMA spring b. SMA spring a and SMA spring b are located above and below the intermediate support, respectively. The intermediate support is equipped with two miniature electromagnetic locks; the support platform of the connecting seat is provided with locking holes; the miniature electromagnetic locks are directly opposite the support platform on their outer side; in the locked state, the lock cylinder of the miniature electromagnetic lock passes through the outer wall of the intermediate support and is located in the corresponding locking hole; The miniature electromagnetic lock is in a de-energized state, and the joint is in a locked state; simultaneously, SMA springs a and b are in a state of force equilibrium. Through circuit control, the miniature electromagnetic lock cylinder retracts, meeting the unlocking condition; the SMA spring b is heated, returning to its initial state, the overall structure contracts, and the SMA spring a is stretched and enters a low-temperature martensitic state; simultaneously, the miniature electromagnetic lock circuit is disconnected, and the lock cylinder springs back. When the miniature electromagnetic lock is energized, the lock cylinder retracts, meeting the unlocking condition; the SMA spring a is heated, spring a returns to its initial state, the overall structure unfolds again, and the SMA spring b is stretched and enters a low-temperature martensitic state; When the power to the miniature electromagnetic lock is cut off, the lock cylinder pops out, the locking structure resets, and the overall structure is relocked.

2. The antenna extension / retraction joint according to claim 1, characterized in that, The SMA springs a and b extend in parallel directions, and each has two springs.

3. The antenna extension / retraction joint according to claim 1, characterized in that, One end of the spring connector is connected to an SMA spring, and the other end is hinged to the connector seat it is located in.

4. The antenna extension / retraction joint according to claim 1, characterized in that, The inner side of the connecting seat has a support platform; the extended connecting end of the intermediate support and the support platform are located on both sides of the bearing, and are connected to the bearing.

5. The antenna retraction joint according to claim 1, characterized in that, The intermediate support includes a support body and a support cover plate; the support cover plate is fastened to the support body and forms a sealed space; the miniature electromagnetic locks are all located within the sealed space; the outer side of the support body is provided with an extension connection end integrated with it. Each support platform has bearings on both sides, for a total of four bearings; The outer sides of the bearings on both sides of the support platform are the end of the support cover plate and the extension connection end, respectively.

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