57 MHz out-line type glass steel antenna

Abstract

The utility model discloses a 57MHz out line formula glass reinforced plastic antenna, including glass reinforced plastic pipe, glass reinforced plastic joint, glass reinforced plastic pipe cap, radiation copper pipe, loading coil, PCB board, coaxial line, SMA joint and auxiliary line. Radiation copper pipe sets up in the inside upper end of glass reinforced plastic pipe, and loading coil one end is connected with radiation copper pipe and is welded, and the other end is connected with PCB board and is welded, forms electrical path, PCB board fixed mounting is in the inside lower end of glass reinforced plastic pipe, and the inner conductor of coaxial line is connected with loading coil, and the outer conductor is connected with the big pad of PCB board. The structure effectively improves the sealing and the protective property of antenna, avoids the problem that traditional external feeding structure is damp, oxidizes, and the contact is bad, compact structure, convenient installation has good standing wave characteristic and stable impedance matching, is applicable to the wireless communication under the harsh environment such as high humidity, high dust, high vibration of underground mine, tunnel.

Description

Technical Field

[0001] This utility model relates to the field of antennas, specifically to a 57MHz wire-out fiberglass antenna. Background Technology

[0002] The 57MHz band falls within the Very High Frequency (VHF, 30MHz–300MHz) range, with a wavelength of approximately 5.26 meters. It possesses excellent diffraction capabilities and strong rock penetration characteristics, making it widely used in wireless communication systems in enclosed and complex environments such as underground mines, tunnels, and utility tunnels. In the field of mine communication, this band is primarily used for personnel positioning systems, dispatch communication systems, wireless sensing and telemetry systems, and emergency rescue communication systems, enabling stable transmission of voice, data, and positioning signals via wireless transmission.

[0003] However, underground mine environments are typically long, narrow, enclosed structures with numerous metal supports, and humidity levels often exceed 90% year-round, accompanied by complex factors such as dust, water droplets, vibration, and temperature variations. Electromagnetic waves cannot propagate freely in such environments; their propagation paths are prone to multiple reflections and strong attenuation, exhibiting a significant waveguide effect. Due to space constraints and structural complexity, traditional antennas face numerous difficulties in installation and maintenance, particularly due to their large size, exposed interfaces, and susceptibility to moisture and corrosion, leading to decreased communication quality, poor equipment reliability, and high maintenance costs.

[0004] Existing 57MHz fiberglass antennas generally employ a direct-output threaded connector structure, typically ranging in size from 1.3 to 3.3 meters. While this structure provides some protection, its large length and high space requirements make it unsuitable for confined spaces such as mines. Furthermore, the feed interface of direct-output structures is often an exposed connector, susceptible to poor contact due to moisture, oxidation, or vibration, leading to increased VSWR, signal loss, and communication interruptions. Simultaneously, traditional antennas often require an external grounding network or additional support to maintain stable performance, further increasing installation difficulty and operating costs. Utility Model Content

[0005] To address the aforementioned issues, this invention provides a 57MHz wire-out fiberglass antenna. The antenna should be able to operate stably for extended periods in harsh environments characterized by high humidity, high dust, and high vibration. Simultaneously, it should ensure stable impedance matching between the antenna and communication equipment, low VSWR, and low transmission loss, thereby achieving highly reliable and low-maintenance underground communication applications.

[0006] This utility model is achieved through the following technical solution: a 57MHz wire-out fiberglass antenna, comprising:

[0007] Fiberglass pipe;

[0008] A fiberglass connector is installed at the bottom end of the fiberglass pipe;

[0009] A fiberglass pipe cap is installed on the top of the fiberglass pipe;

[0010] A radiating copper tube is disposed at the upper inner end of the fiberglass tube;

[0011] A loading coil is provided, one end of which is electrically connected to the radiating copper tube, and the other end is electrically connected to the PCB board.

[0012] The PCB board is fixedly installed inside the lower end of the fiberglass tube and is used for electrical connection of the loading coil, coaxial line and auxiliary line;

[0013] The coaxial cable has its inner conductor electrically connected to the loading coil and its outer conductor electrically connected to the large pad on the PCB board.

[0014] An SMA connector is installed at the outer end of the coaxial cable;

[0015] Auxiliary lines are soldered to the outer conductor of the coaxial line and electrically connected to the PCB board.

[0016] The fiberglass pipe, fiberglass pipe cap, and fiberglass joint are fixed and bonded together with sealant. The coaxial line and auxiliary line pass through the fiberglass joint and lead out from the bottom of the antenna, thus forming a cable-out structure.

[0017] The radiating copper tube is a pure copper tube with a diameter of 12mm and a length of 200mm, used to increase the conductive surface area, reduce high-frequency loss and improve mechanical strength.

[0018] As a preferred technical solution, the loading coil is a nickel-plated carbon steel spring with a diameter of 1.5mm, a length of 15mm, and a length of 130mm. It is located at the bottom of the antenna and is used to compensate for the capacitive reactance of the antenna, so that the antenna input impedance is close to 50Ω and resonance is achieved at 57MHz.

[0019] As a preferred technical solution, the auxiliary line is an electronic wire with a diameter of 3.1 mm and a length of 1.316 m, used as a 1 / 4 wavelength reflective ground wire, and the outer sheath is made of polyurethane material.

[0020] As a preferred technical solution, the surface of the fiberglass joint is treated with a ternary alloy coating.

[0021] As a preferred technical solution, a double-walled heat-shrink tubing is fitted at the weld joint between the radiating copper tube and the loading coil. After heating and shrinking, a waterproof layer is formed to enhance mechanical strength and prevent the weld joint from getting damp.

[0022] As a preferred technical solution, sponge is provided between the radiating copper tube, the loading coil and the inner wall of the fiberglass tube to keep the antenna radiator centered and prevent it from shaking.

[0023] As a preferred technical solution, the power supply points on the PCB are encapsulated with epoxy sealant, with an encapsulation layer thickness of 5–8 mm, to prevent moisture, provide insulation, and fix the solder joints.

[0024] As a preferred technical solution, the joint between the fiberglass pipe and the fiberglass joint is completely sealed after being filled with sealant.

[0025] As a preferred technical solution, the total length of the antenna body after combining the radiating copper tube, the loading coil, and the auxiliary line is 400mm.

[0026] The beneficial effects of this invention are as follows: By employing a combination design of a radiating copper tube, a loading coil, and auxiliary lines inside the antenna, the antenna's physical length is significantly shortened to approximately 400mm while maintaining excellent electrical performance. This allows for good resonance at 57MHz, with a VSWR of less than 1.5 and an impedance close to 50Ω, thus achieving high-efficiency radiation and stable energy transmission. The outgoing cable design allows the coaxial cable and auxiliary lines to be directly led out from the bottom of the antenna, with the feed point completely encapsulated inside the antenna. This avoids problems such as oxidation, water ingress, and poor contact of external connectors in high humidity, high dust, or salt spray environments, significantly improving long-term reliability and VSWR stability.

[0027] Meanwhile, the fiberglass pipe, fiberglass joint, and fiberglass pipe cap are bonded together with sealant to form an overall closed structure. Combined with the double-walled heat shrink tubing at the weld points and the internal epoxy sealant, this effectively prevents moisture intrusion and ensures that the antenna still has excellent moisture-proof, dust-proof, and corrosion-proof performance in harsh environments.

[0028] The radiating copper tube is made of pure copper with a diameter of 12mm, which has good conductivity, can reduce high-frequency loss and improve gain; the loading coil adopts a nickel-plated carbon steel spring structure, which has stable inductance characteristics and also serves as structural support; the auxiliary line is designed as a 1 / 4 wavelength reflection line to further optimize the antenna's radiation characteristics and make the signal radiation more uniform. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0031] Figure 2 This is a schematic diagram of the internal structure of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the radiating copper tube of this utility model;

[0033] Figure 4 This is a schematic diagram of the loading coil of this utility model;

[0034] Figure 5 This is a schematic diagram of the PCB board structure of this utility model;

[0035] Figure 6 This is a schematic diagram of the fiberglass joint of this utility model;

[0036] Figure 7 This is a return loss diagram in the passive data of this utility model;

[0037] Figure 8 This is a standing wave ratio (SWR) plot in the passive data of this utility model.

[0038] Figure 9 This is the Smith chart in the passive data of this utility model. Detailed Implementation

[0039] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0040] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0041] like Figures 1-9 As shown, this utility model discloses a 57MHz wire-type fiberglass antenna. By integrating the radiator, electrical connection structure, and sealing protection structure into a single design, it achieves a comprehensive effect of small size, strong sealing, convenient installation, and stable electrical performance. The antenna mainly consists of a fiberglass tube 2, a fiberglass connector 3, a fiberglass tube cap 1, a radiating copper tube 8, a loading coil 10, a PCB board 11, a coaxial cable 5, an SMA connector 6, and auxiliary lines 7. The various parts are connected by electrical connections, mechanical fixation, and sealing bonding to form a compact, closed, and complete whole.

[0042] In the specific implementation process, a fiberglass tube 2, possessing excellent mechanical strength and weather resistance, is first selected as the main body of the antenna casing. Fiberglass tube caps 1 and fiberglass connectors 3 are installed at both ends of the fiberglass tube 2. The fiberglass tube caps 1 are installed at the upper end of the fiberglass tube 2 to seal the top of the antenna and provide mechanical support; the fiberglass connectors 3 are installed at the bottom end of the fiberglass tube 2, and have internal outlet holes for coaxial cables 5 and auxiliary cables 7 to pass through. The fiberglass tube caps 1, fiberglass tube 2, and fiberglass connectors 3 are fixedly bonded together using weather-resistant sealant. After curing, the sealant forms a highly elastic waterproof layer, effectively preventing moisture, dust, or salt spray from penetrating, while maintaining a stable bond under wind loads or vibrations. This bonding method not only ensures the overall airtightness and protective performance of the antenna but also enhances its resistance to mechanical shock, making the antenna suitable for high humidity, high vibration, and dusty environments.

[0043] A radiating copper tube 8 is installed at the upper end of the fiberglass tube 2, serving as the main radiator of the antenna. The radiating copper tube 8 is made of high-purity copper with a diameter of 12mm and a length of 200mm. The copper material has a high surface finish and good conductivity, effectively reducing surface current density and energy loss caused by the skin effect under high-frequency operating conditions. The larger diameter provides a wider electrical bandwidth, resulting in a wider resonance range and lower VSWR for the antenna around 57MHz, thereby improving overall transmission and reception efficiency. Since the top of the antenna is significantly affected by wind and vibration, the wall thickness and diameter of the radiating copper tube 8 have been optimized to significantly improve structural strength and prevent bending or breakage after prolonged use.

[0044] The loading coil 10 is mounted below the radiating copper tube 8. One end is inserted into the constricted portion of the radiating copper tube 8 and securely connected by soldering, while the other end is soldered to a small pad on the PCB board 11. The loading coil 10 is made of nickel-plated carbon steel spring wire with a diameter of 1.5mm, a diameter of 15mm, and a length of 130mm, exhibiting good conductivity and elastic recovery performance. The loading coil 10 acts as inductance compensation in the antenna's electrical structure, counteracting the capacitive reactance of the radiator, making the overall antenna's input impedance close to 50Ω, and achieving optimal resonance at 57MHz. The presence of the loading coil 10 is equivalent to extending the antenna's electrical length within a limited physical length, thus maintaining radiation performance while shortening the overall size. The nickel plating prevents oxidation of the coil surface, improves corrosion resistance, and enhances mechanical stability, ensuring the antenna does not degrade during long-term use in humid mine or outdoor environments.

[0045] A section of double-walled heat-shrink tubing 4 is fitted over the weld joint between the radiating copper tube 8 and the loading coil 10. After welding, a heating process is used to shrink the heat-shrink tubing 4 and cover the surface of the weld joint, forming a dense waterproof layer. This waterproof layer can further improve the mechanical strength of the welded joint, prevent the weld joint from loosening or breaking due to vibration during transportation or use, and isolate air and moisture to prevent the weld joint from failing due to condensation or corrosion.

[0046] A PCB board 11 is installed below the loading coil 10, inside the lower end of the fiberglass tube 2. The PCB board 11 is mainly used for power supply connection and signal transmission. Small and large pads are arranged on the PCB board 11. The lower end of the loading coil 10 is soldered to the small pad, forming an electrical path. The inner conductor of the coaxial line 5 is soldered to the interface of the loading coil 10, and the large pad is connected to the outer conductor of the coaxial line 5. The auxiliary line 7 is also soldered to the same point as the outer conductor, thus forming a complete power supply loop. After the PCB board 11 is installed, its solder joints and connections are encapsulated with epoxy sealant. The thickness of the encapsulation layer is controlled between 5 and 8 mm, forming a robust insulating and moisture-proof layer after curing. This encapsulation layer not only effectively blocks moisture penetration but also fixes the position of each connector, preventing loosening caused by external force or vibration.

[0047] Coaxial cable 5 uses RG316 double-silver shielded cable, which has low transmission loss and excellent anti-interference performance. One end is connected to PCB board 11, and the other end is connected to SMA connector 6. SMA connector 6 serves as an external device connection interface and is installed at the free end of coaxial cable 5. The outer shell of SMA connector 6 is made of metal anti-oxidation material, which can firmly connect with communication equipment and ensure low-loss signal transmission. Coaxial cable 5 and auxiliary line 7 pass through the outlet hole of fiberglass connector 3 and are led out to the outside of the antenna. The outlet of fiberglass connector 3 is completely filled and sealed with sealant, and then covered with a section of double-wall heat shrink tubing 4 to protect the outlet area and further enhance waterproof and moisture-proof performance.

[0048] Auxiliary line 7 is an electronic wire with a diameter of 3.1 mm and a length of 1.316 m, approximately one-quarter of the operating wavelength, used as a reflective ground wire. The outer sheath of auxiliary line 7 is made of polyurethane, which has excellent wear resistance, oil resistance, chemical corrosion resistance, and UV resistance, maintaining long-term insulation stability in environments with high humidity, high salt spray, and large temperature differences. The introduction of auxiliary line 7 enables the antenna to achieve near-vertical polarized omnidirectional radiation characteristics during operation, improving signal propagation uniformity and reducing the impact of ground interference, ensuring the stability of the communication system in complex spaces.

[0049] During assembly, to prevent the radiator from swaying inside the fiberglass tube 2, sponge 9 is attached around the upper part of the radiating copper tube 8 and the outer periphery of the middle part of the loading coil 10. The sponge 9 material has elastic recovery force, which can keep the radiator in a centered position inside the fiberglass tube 2 and absorb impact energy during transportation or vibration, protecting the internal solder joints from stress damage. This structural design ensures that the antenna maintains stable electrical performance when subjected to external impact, wind load, or equipment vibration.

[0050] After all internal components are assembled, the radiator assembly is inserted into the fiberglass tube 2 and fixed with the fiberglass connector 3. Then, sealant is evenly applied to the connection points of the fiberglass tube cap 1, the fiberglass tube 2, and the fiberglass connector 3 for sealing. Once the sealant has fully cured, a completely sealed structure is formed. The final antenna has a total length of approximately 400mm, which is more than 70% shorter than a traditional 57MHz fiberglass antenna, greatly improving installation flexibility and making it particularly suitable for installation in mines, tunnels, vehicle-mounted locations, or other space-constrained environments.

[0051] In practical applications, this antenna achieves good resonance at 57MHz through the synergistic effect of the radiating copper tube 8, the loading coil 10, and the auxiliary line 7, with a VSWR of less than 1.5 and an impedance matching close to 50Ω, ensuring efficient energy transmission. The internal feeding method with an outgoing wire structure reduces external connection points, fundamentally eliminating potential problems such as poor contact, high signal loss, and incomplete waterproofing. The fiberglass shell and sealed structure provide excellent protection, enabling the antenna to maintain stable mechanical strength and electrical performance even under long-term operation in high humidity, high salt spray, and strong vibration environments. It boasts significant advantages such as easy installation, maintenance-free operation, high reliability, and long service life.

[0052] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope defined in the claims.

Claims

1. A 57MHz wire-out fiberglass antenna, characterized in that, include: Fiberglass pipe (2); A fiberglass connector (3) is installed at the bottom end of the fiberglass pipe (2); A fiberglass pipe cap (1) is installed on the top of the fiberglass pipe (2); A radiating copper tube (8) is disposed at the upper inner end of the fiberglass tube (2); A loading coil (10) is electrically connected at one end to the radiating copper tube (8) and at the other end to the PCB board (11); PCB board (11) is fixedly installed inside the lower end of the fiberglass tube (2) for electrical connection of loading coil (10), coaxial line (5) and auxiliary line (7); The coaxial line (5) has its inner conductor electrically connected to the loading coil (10) and its outer conductor electrically connected to the large pad on the PCB board (11). SMA connector (6) is installed at the outer end of the coaxial line (5); The auxiliary line (7) is soldered to the outer conductor of the coaxial line (5) and electrically connected to the PCB board (11); The fiberglass pipe (2), fiberglass pipe cap (1) and fiberglass connector (3) are fixedly bonded together with sealant. The coaxial line (5) and auxiliary line (7) pass through the fiberglass connector (3) and are led out from the bottom of the antenna, thus forming a wire-out structure.

2. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The radiation copper tube (8) is a pure copper tube with a diameter of 12 mm and a length of 200 mm, used to increase the conductive surface area, reduce high-frequency loss and improve mechanical strength.

3. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The loading coil (10) is a nickel-plated carbon steel spring with a diameter of 1.5 mm, a diameter of 15 mm, and a length of 130 mm. It is located at the bottom of the antenna and is used to compensate for the capacitive reactance of the antenna, so that the antenna input impedance is close to 50 Ω and resonance is achieved at 57 MHz.

4. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The auxiliary line (7) is an electronic line with a diameter of 3.1 mm and a length of 1.316 m, used as a 1 / 4 wavelength reflective ground wire, and the outer sheath is made of polyurethane material.

5. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The surface of the fiberglass connector (3) is treated with a ternary alloy coating.

6. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The weld between the radiating copper tube (8) and the loading coil (10) is fitted with a double-walled heat shrink tube (4), which forms a waterproof layer after heating and shrinking, thereby enhancing mechanical strength and preventing the weld from getting damp.

7. The 57MHz wire-type fiberglass antenna according to claim 1, characterized in that: Sponge (9) is provided between the radiating copper tube, the loading coil and the inner wall of the fiberglass tube to keep the antenna radiator centered and prevent it from shaking.

8. The 57MHz wire-type fiberglass antenna according to claim 1, characterized in that: The power supply points on the PCB board (11) are encapsulated with epoxy sealant, with an encapsulation layer thickness of 5–8 mm, to prevent moisture, provide insulation, and fix the solder joints.

9. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The joint between the fiberglass pipe (2) and the fiberglass connector (3) is completely sealed after being filled with sealant.

10. The 57MHz wire-out fiberglass antenna according to claim 1, characterized in that: The total length of the antenna body after the combination of the radiating copper tube (8), the loading coil (10) and the auxiliary line (7) is 400mm.

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