A retractable log-periodic antenna

Abstract

This invention discloses a deployable log-periodic antenna, relating to the field of antenna technology. It includes an antenna body, which is mounted on the lower end of a UAV. The antenna body comprises an upper connecting plate, a lower connecting plate, a fixing rod, a vertical travel electronic lock, a vertical lifting spring assembly, a pulley, a connecting wire, a joint, a connecting rod, and a first vibrator winding device. A lower connecting plate is located at the lower end of the upper connecting plate, and a fixing rod is located at the lower end of the lower connecting plate. Vertical travel electronic locks are installed between the upper and lower connecting plates and between the lower connecting plate and the fixing rod. The beneficial effects of this invention, employing a high-rigidity, highly deployable log-periodic antenna, are self-deploying, large in size, and have low areal density.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, specifically to a retractable log-periodic antenna. Background Technology

[0002] Log-periodic antennas are a type of directional panel antenna, a broadband antenna, or frequency-independent antenna, commonly used for indoor distribution and elevator signal coverage. They are primarily used in the VHF / UHF band and can also serve as shortwave communication antennas and medium-wave / shortwave broadcast antennas. Furthermore, log-periodic antennas can be used as feed sources for microwave reflector antennas. Currently, log-periodic antennas are frequently used in a novel reconnaissance and early warning system combining a ground-based vehicle and a multi-rotor UAV. The ground-based vehicle reaches a designated location, the antenna is fixed to the multi-rotor UAV, and the UAV carries the antenna into the air. The antenna is connected via cable to the communication terminal on the ground-based vehicle for direct signal transmission. The antenna becomes active once the multi-rotor UAV 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, heavy, and consumes a lot of energy. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing an ultra-large deployable log-periodic antenna suitable for use on unmanned aerial vehicles (UAVs) and a method for its storage. It employs a novel shape memory alloy material for the key design of the deployable antenna and a high-rigidity, high-strength carbon fiber material for the antenna structure frame design, thereby achieving the design and manufacture of an ultra-lightweight novel deployable log-periodic antenna structure.

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

[0006] A retractable log-periodic antenna includes multiple antenna elements; it also includes an upper support rod 21, a middle support rod 22, and a lower support rod 23; the upper support rod 21, the middle support rod 22, and the lower support rod 23 are arranged in parallel, wherein the middle support rod 22 is located between the upper support rod 21 and the lower support rod 23; a travel electronic lock 24 is provided between the upper support rod 21 and the middle support rod 22, and between the middle support rod 22 and the lower support rod 23;

[0007] The upper support rod 21 has a tension spring assembly 25 at both the left and right ends. The two tension spring assemblies 25 are equipped with pulleys 26 on their outer sides. A connecting line 261 is wound around the pulley 26. One end of the connecting line is connected to the actuating end of the tension spring assembly, and the other end of the connecting line 261 passes through two travel electronic locks 24 in sequence and is fixed to the lower support rod 23.

[0008] The antenna vibrator is mounted on the central support rod.

[0009] Furthermore, the pulley is mounted on the upper support rod 21.

[0010] Furthermore, both ends of the upper support rod 21, the middle support rod 22, and the lower support rod 23 are connected to joints 27, and the other end of the joints 27 is equipped with an extension rod 28.

[0011] Furthermore, multiple vibrator winding devices are provided on the upper support rod, the lower support rod, and the extension rod connected to the upper support rod and the lower support rod; multiple antenna vibrators are arranged on the middle support rod and the extension rod connected to the middle support rod.

[0012] The middle part of the antenna vibrator is connected to the corresponding central support rod and extension rod, and the two ends of the antenna vibrator are respectively connected to the corresponding vibrator winding device, which realizes the winding and unwinding of the line.

[0013] Furthermore, two travel electronic locks are respectively installed at the bottom of the upper support rod and on the middle support rod.

[0014] Furthermore, the tension spring assembly 25 includes an SMA tension spring and a spring constraint member; the SMA tension spring extends or shortens along the spring constraint member;

[0015] One end of the SMA tension spring is fixed, and the other end is connected to the connecting wire; the circuit controls the extension and shortening of the SMA tension spring.

[0016] Furthermore, the spring constraint component is a rod; the rod is fixedly installed on the upper support rod, and one end of the SMA tension spring is fixedly connected to the rod.

[0017] Furthermore, the spring constraint component is a sliding groove located at the bottom of the upper support rod; both ends of the SMA tension spring are provided with sliding blocks; the sliding blocks are all suspended in the sliding groove, one of the sliding blocks is fixed in the sliding groove, and the other sliding block is connected to one end of the connecting line.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This device employs a novel shape memory alloy material for its retractable key design and high-rigidity, high-strength carbon fiber material for its antenna structure frame design, thereby achieving the design and manufacture of an ultra-lightweight, novel retractable log-periodic antenna structure. The total weight of the antenna is 8kg, which is 1 to 2 orders of magnitude lighter than current retractable log-periodic antennas in the same frequency band. The retractable log-periodic antenna has the advantages of self-retraction, large size, and low areal density. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the UAV carrying this embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the antenna body in this invention.

[0022] Figure 3 This is an unfolded view of the antenna body in this invention.

[0023] Figure 4 This is a vertical orientation diagram of the antenna body in this invention.

[0024] Figure 5 This is a schematic diagram of the right-hand structure in this invention.

[0025] Figure 6 This is a schematic diagram of the left side of the structure in this invention.

[0026] Figure 7 yes Figure 4 Enlarged view of A in the middle.

[0027] Figure 8 yes Figure 5 Enlarged view of B in the middle.

[0028] Figure 9 This is a top view of the support rod and extension rod in the stowed state of the present invention.

[0029] Figure 10 This is a schematic diagram of the joint structure according to an embodiment of the present invention;

[0030] Figure 11 This is a schematic diagram of the joint structure in the unfolded state according to an embodiment of the present invention;

[0031] Figure 12 This is a schematic diagram of the joint structure in the stowed state according to an embodiment of the present invention;

[0032] Figure 13 This is an exploded view of the joint structure according to an embodiment of the present invention;

[0033] Figure 14 This is a schematic diagram of the connecting plate of the joint and its bearing in an embodiment of the present invention.

[0034] Figure 15 This is a schematic diagram of one structure of the tension spring assembly in an embodiment of the present invention;

[0035] Figure 16 This is a schematic diagram of the second mechanism of the tension spring assembly in an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached drawings: UAV 1, antenna body 2, antenna vibrator 3, upper support rod 21, middle support rod 22, lower support rod 23, travel electronic lock 24, tension spring assembly 25, pulley 26, joint 27, connecting rod 28, first vibrator winding device 29, connector 211, second vibrator winding device 212, connecting line 261, connecting block 231.

[0037] 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 connecting end; 27-10, Locking hole.

[0038] 25-11, Rod; 25-22, 25-2, SMA tension spring; 25-1, Sliding block. Detailed Implementation

[0039] 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.

[0040] See Figure 1-8 As shown, the technical solution adopted in this embodiment is: an ultra-large deployable log-periodic antenna suitable for drone mounting, which includes a drone 1 and an antenna body 2, with several antenna bodies 2 installed at the lower end of the drone 1;

[0041] The antenna body 2 includes an upper support rod 21, a middle support rod 22, a lower support rod 23, a travel electronic lock 24, a tension spring assembly 25, a pulley 26, a connecting line 261, a joint 27, a connecting rod 28, and a first vibrator winding device 29. Connectors 211 are fixedly installed on both sides of the upper support rod 21. The other end of the connector 211 is rotatably connected to the joint 27. The other end of the joint 27 is rotatably connected to the connecting rod 28. The lower inner side of the two connecting rods 28 is provided with the first vibrator winding device 29, which is located next to the joint 27.

[0042] Both ends of the central support rod 22 are provided with connectors 211, and the other end of the connector 211 is rotatably connected to a connecting rod 28.

[0043] Both ends of the lower support rod 23 are provided with connecting blocks 231, which are L-shaped. The connecting blocks 231 are rotatably connected to one end of the joint 27, and the other end of the joint 27 is connected to a connecting rod 28. The upper inner side of the two connecting rods 28 is provided with a first vibrator winding device 29, which is located on the side of the joint 27. The upper end of the connecting block 231 is connected to the bottom end of a travel electronic lock 24, the upper end of the travel electronic lock 24 is connected to the bottom side of the middle support rod 22, the top end of the connecting piece 211 on the side of the middle support rod 22 is connected to the bottom end of another travel electronic lock 24, and the upper end of the travel electronic lock 24 is connected to the bottom side of the upper support rod 21.

[0044] The upper support rod 21 has tension spring groups 25 installed at both its left and right ends. A pulley 26 is connected to the outer side of each tension spring group 25, and a connecting wire 261 is installed on the pulley 26. The lower end of the connecting wire 261 passes through two travel electronic locks 24 and connects to the bottom end of the lower support rod 28. Several antenna elements 3 are installed on the middle support rod 22 and the connecting rods 28 at both ends. The two ends of the antenna elements 3 are located within the winding coil 29 relative to the first element. The connecting block 231 is L-shaped. In the deployed state, the circular antenna is vertically lifted by the thermal restoring force of the shape memory alloy (SMA) springs in the tension spring groups 25. After reaching its position, the travel electromagnetic locks lock the structure to prevent it from falling back. Then, under the action of the six antagonistic SMA joints 27, it retracts in an S-shape in the horizontal direction.

[0045] In this embodiment, the short antenna element is wound around the element winding device via an auxiliary wire connected to its end.

[0046] The joint 27 is an antagonistic shape memory alloy joint.

[0047] The connecting rod 28 is a carbon fiber tube.

[0048] The lower right end of the upper support rod 21 is provided with a second oscillator winding device 212, which collects the connecting wire 261.

[0049] This embodiment provides two structural forms of tension spring assemblies, refer to... Figure 15 In one structural form, the spring constraint component is a rod; the rod is fixedly installed on the upper support rod, and one end of the SMA tension spring is fixedly connected to the rod.

[0050] Reference Figure 16 In the second structural form, the spring constraint component is a sliding groove located at the bottom of the upper support rod; both ends of the SMA tension spring are provided with sliding blocks; the sliding blocks are all suspended in the sliding groove, one of the sliding blocks is fixed in the sliding groove, and the other sliding block is connected to one end of the connecting line.

[0051] A method for storing an ultra-large deployable log-periodic antenna suitable for use on unmanned aerial vehicles (UAVs) includes the following steps:

[0052] Step 1: First, the antenna is retracted vertically. In the unfolded state, the lifting spring assembly 25 generates a restoring force through heating. This restoring force is greater than the antenna's own weight, which exerts a force on the pulley 26, thereby driving the connecting line 261 and causing the middle support rod 22 and the lower support rod 23 to rise, thus lifting the antenna vertically. At room temperature, in the retracted state, the vertical lifting spring assembly 25 is stretched under the antenna's own weight, and a stress-induced martensitic phase transformation occurs, thus pulling the antenna vertically open along with the flexible rope. The 27MHz-110MHz vertically polarized log-periodic antenna is raised and lowered vertically by using two layers of long-stroke variable vertical lifting spring assemblies 25 in conjunction with the pulley assembly.

[0053] A long-stroke SMA lifting spring, driven by current, is used in conjunction with a pulley system to achieve a 4:1 stroke scaling, enabling a vertical reverse displacement of 220cm from a 55cm stroke variation. This two-layer SMA lifting spring + pulley system scheme allows for a five-meter vertical elevation adjustment of the antenna.

[0054] Step 2: Then, the antenna is retracted horizontally. Joint 27 can drive the connecting rod 28 to retract through current excitation control, achieving S-shaped retraction in the horizontal direction.

[0055] The joints in this embodiment are specifically referred to. Figures 10 to 14 The joint in 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.

[0056] The SMA springs a and b extend in parallel directions, and each has two springs.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] Each support platform has bearings on both sides, for a total of four bearings;

[0062] 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.

[0063] The steps of joint adduction and abduction can be summarized as follows:

[0064] Initial state as Figure 11 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.

[0065] The first step involves retracting the miniature electromagnetic lock cylinder through circuit control, thus unlocking the lock.

[0066] 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. (Refer to...) Figure 12 .

[0067] 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 is then in a low-temperature martensitic state.

[0068] Fourth step: the miniature electromagnetic lock is de-energized, the lock cylinder pops out, the locking structure resets, and the overall structure is re-locked.

[0069] This completes one cycle of opening and closing.

[0070] This specific embodiment of the log-periodic antenna features automatic deployment and folding capabilities. The antenna is vertically suspended from the bottom support of the UAV platform. It deploys after takeoff and folds back before landing. The maximum dimensions of the deployed log-periodic antenna are 5000mm × 4500mm × 50mm; the maximum dimensions of the folded antenna are 2200mm × 600mm × 300mm. With a total power of less than 200W, the deployment time is less than 210s, and the folding time is less than 150s. This novel deployable log-periodic antenna offers advantages such as self-deployment, large size, and low surface density. The weight of a single antenna is no more than 7 kg, and the antenna in this device has a certain degree of wind resistance.

[0071] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A retractable log-periodic antenna, comprising multiple antenna elements; employing high-stiffness, high-strength carbon fiber material for the antenna structural frame; characterized in that, It also includes an upper support rod (21), a middle support rod (22), and a lower support rod (23); the upper support rod (21), the middle support rod (22), and the lower support rod (23) are arranged in parallel, wherein the middle support rod (22) is located between the upper support rod (21) and the lower support rod (23); a travel electronic lock (24) is provided between the upper support rod (21) and the middle support rod (22) and between the middle support rod (22) and the lower support rod (23); The upper support rod (21) is equipped with tension spring groups (25) at both the left and right ends. The two tension spring groups (25) are equipped with pulleys (26) on their outer sides. A connecting line (261) is wound around the pulley (26). One end of the connecting line is connected to the actuating end of the tension spring group. The other end of the connecting line (261) passes through two travel electronic locks (24) in sequence and is fixed to the lower support rod (23). The antenna vibrator is installed on the middle support rod. The upper support rod (21), the middle support rod (22), and the lower support rod (23) are all connected to joints (27) at both ends, and an extension rod (28) is installed at the other end of the joint (27). Multiple vibrator winding devices are provided on the upper support rod, the lower support rod, and the extension rod connected to the upper support rod and the lower support rod; multiple antenna vibrators are arranged on the middle support rod and the extension rod connected to the middle support rod; The middle part of the antenna vibrator is connected to the corresponding central support rod and extension rod, and the two ends of the antenna vibrator are respectively connected to the corresponding vibrator winding device, which realizes the winding and unwinding of the line.

2. The deployable log-periodic antenna according to claim 1, characterized in that, The pulley is mounted on the upper support rod (21).

3. The deployable log-periodic antenna according to claim 1, characterized in that, Two travel electronic locks are installed at the bottom of the upper support rod and on the middle support rod, respectively.

4. The deployable log-periodic antenna according to claim 1, characterized in that, The tension spring assembly (25) includes an SMA tension spring and a spring constraint component; the SMA tension spring extends or shortens along the spring constraint component; One end of the SMA tension spring is fixed, and the other end is connected to the connecting wire; the circuit controls the extension and shortening of the SMA tension spring.

5. A deployable log-periodic antenna according to claim 4, characterized in that, The spring constraint component is a rod; the rod is fixedly installed on the upper support rod, and one end of the SMA tension spring is fixedly connected to the rod.

6. A deployable log-periodic antenna according to claim 4, characterized in that, The spring constraint component is a sliding groove located at the bottom of the upper support rod; both ends of the SMA tension spring are provided with sliding blocks; the sliding blocks are all suspended in the sliding groove, one of the sliding blocks is fixed in the sliding groove, and the other sliding block is connected to one end of the connecting line.

Images