Airborne honeycomb structure tubular short-wave antenna and manufacturing method thereof

Abstract

The invention discloses an airborne honeycomb structure tubular short-wave antenna and a manufacturing method thereof. An inner core is formed by prepreg of quartz fiber fabric and epoxy resin and serves as a load-bearing main material of the tubular short-wave antenna; winding a copper pipe on the outer surface of the quartz fiber fabric and epoxy resin inner core layer according to a fixed screw pitch; winding aramid fiber paper honeycombs in gaps between the screw pitches of the copper pipes for gap filling; then, prepreg of quartz fiber fabric and epoxy resin is laid on the outermost layer to form a tubular short-wave antenna outer cover protection layer, tape winding curing, grinding and polishing are carried out, and the tubular short-wave antenna of the honeycomb structure is formed; and a three-proofing coating is coated outside the tubular short-wave antenna with the honeycomb structure. The tubular short-wave antenna with the honeycomb structure is high in boundary dimension precision, light in weight and good in strength; and the device can bear an environmental test corresponding to the GJB150A standard. Compared with a traditional airborne steel cable antenna, the airborne steel cable antenna has better safety and maintainability; the antenna is lighter than a composite material tubular antenna with a common structure, and the communication level of the antenna is superior to that of an airborne steel cable antenna.

Description

Technical Field

[0001] This invention relates to a tubular shortwave antenna and its manufacturing method, and more particularly to a honeycomb structure tubular shortwave antenna and its manufacturing method. Background Technology

[0002] Currently, most airborne shortwave antennas in my country are steel cable antennas and tubular antennas with ordinary composite material structures. However, steel cable antennas and tubular antennas with ordinary composite material structures have the following shortcomings: High-frequency vibrations from helicopters are the "natural enemy" of cable antennas. The connection points between the cable and the fuselage, as well as the insulators, are highly susceptible to breakage due to metal fatigue. The rotor downwash can also cause the cable to swing violently, leading to the risk of the wire breaking and becoming entangled in the rotor.

[0003] Rotating rotor blades can severely affect, reflect, and interfere with the shortwave signals transmitted / received by cable antennas, leading to signal instability, exacerbated multipath effects, and poor communication quality.

[0004] In low-temperature and humid environments, steel cables are prone to freezing, which alters their electrical properties.

[0005] Ordinary composite material tubular antennas are heavy due to the extensive use of composite materials and their solid structure. This is especially true in the helicopter field, where weight reduction design is a major concern for users. Summary of the Invention

[0006] The purpose of this invention is to provide a cellular structure tubular shortwave antenna and its manufacturing method, which solves the problems of existing steel cable antennas being prone to breakage due to vibration and fatigue; signal instability and poor communication quality caused by rotor rotation; changes in electrical characteristics due to icing in low temperature and humid environments; and the heavy weight of ordinary composite material structure tubular antennas.

[0007] To achieve the above objectives, the present invention provides a cellular structure tubular shortwave antenna using the following technical solution: An airborne cellular structure tubular shortwave antenna, characterized in that: it comprises an inner core layer of quartz epoxy composite material composed of quartz fiber fabric and epoxy resin, a copper tube layer wound around the quartz epoxy composite material layer, an aramid paper honeycomb layer laid in the pitch gap of the copper tube, a quartz epoxy composite material layer laid around the copper tube and the aramid paper honeycomb, and a three-proof coating applied to the outside of the quartz epoxy composite material layer.

[0008] Further preferred, the inner core layer of the quartz epoxy composite material has a wall thickness of 2mm, the diameter of the radiator copper tube is 2.5mm, the thickness of the aramid paper honeycomb layer is 2.5mm, the outer protective layer of the quartz epoxy composite material adopts orthogonal plying with a thickness of 1.5mm, and the thickness of the three-proof coating on the outer surface is 0.05mm.

[0009] A method for manufacturing a cellular structure tubular shortwave antenna includes the following steps: Step 1, Inner core layer preforming: 10 layers of quartz epoxy composite material, serving as the main load-bearing material for the tubular antenna; Step 2, Copper tube winding: Wind a copper tube onto the outer surface of the quartz epoxy composite inner core according to a fixed pitch; Step 3, Aramid paper honeycomb filling: Aramid paper honeycomb winding and filling is carried out within the pitch spacing of the copper tube; Step 4, Outer protective layer installation: Install a quartz epoxy composite material outer protective layer over the copper tube and aramid paper honeycomb layer; Step 5, Wrapping and Curing: Wrap the tubular antenna formed in Steps 1, 2, 3, and 4 with tape, then cure, grind, and polish to form a honeycomb structure tubular shortwave antenna. Step 6, tri-proof treatment: Apply a tri-proof coating to the outside of the honeycomb structure tubular shortwave antenna.

[0010] In a further preferred embodiment, in steps 1 and 5, the curing temperature is 120℃~130℃ and the time is 1.5-2 hours.

[0011] Further preferred, the inner core of the honeycomb tubular shortwave antenna has a wall thickness of 2mm; the copper tube thickness is 2.5mm; the aramid paper honeycomb layer is 2.5mm; and the outer protective layer of the quartz epoxy composite material is 1.5mm thick, using orthogonal layup.

[0012] Further preferably, the three-proof coating is a fluoropolyurethane enamel protective layer with a coating thickness of 0.05 mm.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The cellular structure tubular shortwave antenna boasts high dimensional accuracy, light weight, and high strength; it can withstand environmental tests corresponding to the GJB150A standard. It offers better safety and maintainability than traditional airborne cable antennas; it is lighter than ordinary composite material tubular antennas; and its communication performance surpasses that of airborne cable antennas. Attached Figure Description

[0014] Figure 1 Vibration durability test mounting fixture; Figure 2 Actual installation of a honeycomb structure tubular shortwave antenna; Figure 3 Frequency sweep curve of a cellular tubular shortwave antenna; Figure 4 Simplified geometric model of shortwave skywave communication; Figure 5 Schematic diagram of a honeycomb structure tubular shortwave antenna; Figure 6 Flowchart of the fabrication process for a honeycomb structure tubular shortwave antenna. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 As shown, the present invention provides a honeycomb structure tubular shortwave antenna, comprising a quartz epoxy composite inner core layer 1, a copper tube layer 2 wound around the quartz epoxy composite inner core layer, an aramid paper honeycomb layer 3 laid in the pitch gap of the copper tube, a quartz epoxy composite outer cover layer 4 laid around the copper tube and the aramid paper honeycomb, and a three-proof coating 5 coated around the quartz epoxy composite layer.

[0017] The honeycomb structure tubular shortwave antenna has a quartz epoxy composite inner core layer with a wall thickness of 2mm, a radiator copper tube diameter of 2.5mm, an aramid paper honeycomb layer thickness of 2.5mm, an orthogonal layup outer protective layer of quartz epoxy composite material with a thickness of 1.5mm, and an outer surface three-proof coating thickness of 0.05mm.

[0018] like Figure 2 As shown, the manufacturing method of a cellular structure tubular shortwave antenna includes the following steps: Step 1, Inner core layer preforming: 10 layers of quartz epoxy composite material, serving as the main load-bearing material for the tubular antenna; Step 2, Copper tube winding: Wind a copper tube onto the outer surface of the quartz epoxy composite inner core according to a fixed pitch; Step 3, Aramid paper honeycomb filling: Aramid paper honeycomb winding and filling is carried out within the pitch spacing of the copper tube; Step 4, Outer protective layer installation: Install a quartz epoxy composite material outer protective layer over the copper tube and aramid paper honeycomb layer; Step 5, Wrapping and Curing: Wrap the tubular antenna formed in Steps 1, 2, 3, and 4 with tape, then cure, grind, and polish to form a honeycomb structure tubular shortwave antenna. Step 6, tri-proof treatment: Apply a tri-proof coating to the outside of the honeycomb structure tubular shortwave antenna.

[0019] The method for manufacturing a honeycomb structure tubular shortwave antenna is characterized in that, in steps 1 and 5, the curing temperature is 120℃~130℃ and the time is 1.5-2 hours.

[0020] Structural strength analysis verification: The mechanical properties of quartz epoxy composite materials are shown in the table below:

[0021] Based on the mechanical environment conditions of a certain type of helicopter, modal analysis, sinusoidal vibration analysis, impact analysis, and random vibration analysis were performed on the honeycomb structure tubular shortwave antenna. The simulation analysis results are as follows: Based on the results of sinusoidal vibration, impact response analysis, and random vibration analysis, the safety margin of the cellular structure tubular shortwave antenna is calculated using the following formula: MS= -1 The calculated safety margin MS for the model is 217.9 under sinusoidal vibration, 3.11 under impact load, and 21.2 under random vibration. All calculated safety margins are greater than 0, which meets the design requirements for helicopter airborne shortwave antennas.

[0022] Vibration durability tests were conducted on the cellular structure tubular shortwave antenna to verify its performance.

[0023] Test conclusion: The strength design of the honeycomb structure tubular shortwave antenna is sound and meets the design requirements for helicopter airborne shortwave antennas.

[0024] Electrical performance communication distance analysis: The communication range of airborne shortwave antennas is generally required to be no less than 1000km. Long-distance shortwave communication uses ionospheric reflection as the propagation path.

[0025] The ionosphere is divided into four layers: D, E, F1, and F2. The D layer, at an altitude of 60km–90km, can reflect frequencies of 2MHz–9MHz during the day. The E layer, at an altitude of 85km–150km, has relatively little reflection of shortwave frequencies.

[0026] The F layer has the greatest effect on shortwave reflection and is divided into two layers: F1 and F2. The F1 layer is 150km to 200km high and only functions during the day, while the F2 layer is higher than 200km high and is the main body of the F layer, supporting shortwave propagation both day and night.

[0027] Because ionospheric support is variable, exhibiting both macroscopic patterns and random variations, the internationally accepted ITU-RP shortwave communication prediction scheme currently prevails.

[0028] Estimating the highest acceptable operating frequency (MUF) for radio services involves two steps: 1. Estimating the basic MUF based on consideration of ionospheric parameters; 2. Determine the correction factor for the propagation mechanism that allows frequencies above the MUF.

[0029] The basic maximum usable frequency (MUF) for various propagation modes is estimated based on the corresponding ionospheric critical frequency and a factor corresponding to the hop length. When considering both the E-mode and F2-mode, the two higher basic MUFs of the lowest-order E-mode and F2-mode give the basic MUF of the path. Once the basic MUF median, the median incident skywave field strength, and the usable receiver sensitivity from a lossless receiving antenna with a given gain are determined, daytime shortwave communication range can be assessed.

[0030] Because shortwave wavelengths are relatively long, the attenuation effect of the ground on electromagnetic wave energy is significant when the antenna is not far from the ground. Therefore, the propagation distance of shortwave waves on the ground is limited. The Friesian transmission formula plus additional losses is typically used to predict line-of-sight communication distances. (1) in: (2) (3) In the formula, all parameters are in logarithmic units. Pt is the transmit power, Gt and Gr are the transmit and receive antenna gains, Ld is the ideal propagation loss at distance d at the operating frequency f, Ls is the possible additional loss (including surface medium loss, terrain undulations, etc.), S is the receiver sensitivity, Pn is the local noise power, and SNR is the effective demodulation signal-to-noise ratio. The Earth's radius is approximately 6371 km, and the ionosphere is assumed to have an F2 layer height of 200 km (in reality, the electron rotation frequency of each ionosphere layer causes different reflection heights for different frequencies; the F2 layer reflects shortwave waves all day). The simplified geometric model of shortwave communication is as follows: Figure 4 As shown.

[0031] D=2*((dx / 2)^2+hF2^2)^(1 / 2) ⑷ Where dx = 2Rsin(I / 2R), I = 1000km, R = 6371km, hF2 = 200km.

[0032] Launch elevation angle: At = arcsin(hF² / D) (5) By combining equations (1), (2), (3), (4), and (5), along with the ionospheric refraction loss factor and the simulated transmit antenna elevation gain, the field strength at the receiving point at a distance of 1000km can be estimated, thereby evaluating the quality of shortwave communication.

[0033] Based on the gain pattern obtained from the full-wave simulation of the shortwave antenna, a receiving sensitivity of 85~95dBm@5~30MHz or higher is required to ensure that the shortwave communication quality meets the requirements for a communication distance of 1000km.

[0034] When the sensitivity of the shortwave transceiver is (S+N+D) / (N+D)=12dB, the SSB≤1μV, that is, the sensitivity is 107dBm@5~30MHz, and the margin is 12dBm.

[0035] The simulation results of the shortwave antenna in the 2MHz~30MHz frequency band are shown in Table 1. Since the antenna adopts a spiral winding form, there is a difference in the maximum radiation direction between the low frequency band and the high frequency band.

[0036] Table 1. Statistics of Simulated Gain for Shortwave Antennas

[0037] In summary, shortwave antennas can theoretically meet the communication coverage requirement of 1000km.

[0038] The honeycomb structure tubular shortwave antenna uses aramid paper honeycomb to fill the gaps in the copper spiral structure, which is different from the ordinary structure tubular shortwave antenna that uses composite materials for filling the gaps. Under the same volume conditions, due to the different density, the weight of each meter of shortwave antenna can be reduced by about 25%.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing an airborne cellular structure tubular shortwave antenna as described in claim 1, characterized in that, Includes the following steps: Step 1: Inner core layer pre-forming: Multi-layer quartz epoxy composite material is rolled and formed to form the main load-bearing material of the tubular antenna; Step 2: Copper tube winding. Copper tubes are wound around the outer surface of the inner core layer of the quartz epoxy composite material formed in Step 1 according to a fixed pitch to form a copper tube layer. Step 3: Aramid paper honeycomb filling. Aramid paper honeycomb is filled into the pitch spacing of the copper tube layer formed in step 2 to form an aramid paper honeycomb layer. Step 4: Applying the outer protective layer: Quartz epoxy composite material is applied to the outside of the copper tube layer and the aramid paper honeycomb layer to form a quartz epoxy composite material outer cover layer; Step 5: Wrapping and curing: Wrap the tubular structure processed in steps 1 to 4 with tape, then cure, grind and polish to obtain a semi-finished honeycomb structure tubular shortwave antenna. Step 6: Three-proof treatment. Apply a three-proof coating to the outside of the semi-finished honeycomb structure tubular shortwave antenna obtained in step 5 to obtain the finished airborne honeycomb structure tubular shortwave antenna.

2. The manufacturing method according to claim 1, characterized in that, The curing temperature for both the inner core layer roll preforming in step 1 and the curing in step 5 is 120℃~130℃, and the curing time is 1.5hr~2hr.

3. The manufacturing method according to claim 1, characterized in that, The core layer of the quartz epoxy composite material formed in step 1 has a wall thickness of 2mm; the diameter of the copper tube in step 2 is 2.5mm; the thickness of the aramid paper honeycomb layer in step 3 is 2.5mm; and the outer cover layer of the quartz epoxy composite material in step 4 is laid in an orthogonal layup manner with a thickness of 1.5mm.

4. The manufacturing method according to claim 1, characterized in that, The three-proof coating mentioned in step 6 is a fluoropolyurethane enamel protective layer with a coating thickness of 0.05 mm.

5. The manufacturing method according to claim 1, characterized in that, The quartz epoxy composite material has 10 layers.

6. An airborne cellular tubular shortwave antenna prepared by the method described in claim 1, characterized in that, From the inside out, it includes: an inner core layer of quartz epoxy composite material composed of quartz fiber fabric and epoxy resin, a copper tube layer wrapped around the outer surface of the inner core layer of quartz epoxy composite material, an aramid paper honeycomb layer laid in the pitch gap of the copper tube layer, an outer cover layer of quartz epoxy composite material laid on the outside of the copper tube layer and the aramid paper honeycomb layer, and a three-proof coating coated on the outside of the outer cover layer of quartz epoxy composite material.

7. The airborne cellular tubular shortwave antenna according to claim 6, characterized in that, The inner core layer of the quartz epoxy composite material has a wall thickness of 2 mm; the diameter of the copper tube in the copper tube layer is 2.5 mm; the thickness of the aramid paper honeycomb layer is 2.5 mm; the outer cover layer of the quartz epoxy composite material is laid in an orthogonal layup manner and has a thickness of 1.5 mm; the thickness of the three-proof coating is 0.05 mm.

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