A high-stable-phase low-loss radio frequency feeder cable for 6g communication and a preparation method thereof

Abstract

The application discloses a kind of high stable phase low-loss radio frequency feeder cable for 6G communication and preparation method, from inside to outside in turn include: inner conductor layer;Insulation layer;First shielding layer;Intermediate transition layer;Second shielding layer;Outer sheath layer.The insulation layer of the present application uses the blending foaming system of low-density PTFE and low-molecular-weight PTFE micro powder, nucleating agent, hollow inorganic microspheres and dielectric constant temperature coefficient compensation filler, significantly improves the uniformity and closed cell rate of foaming, makes foaming hole along radial gradient distribution, effectively reduces the dielectric constant fluctuation, reduces the phase temperature coefficient, improves stable phase performance;By controlling formula, foaming process, cooling rate, micro-porous film lap longitudinal package and roll shaping, ensure product consistency and performance stability;Cable is low at 10GHz, return loss is high, shielding efficiency is high, passive intermodulation is low, phase temperature coefficient is small, bending phase stability is good, meet the stringent requirements of 6G communication on radio frequency feeder cable.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically relating to a high-stability, low-loss radio frequency feeder cable for 6G communication and its preparation method. Background Technology

[0002] With the research and deployment of sixth-generation mobile communication (6G) technology, the operating frequency bands of communication systems are further extended to millimeter wave and even terahertz bands, placing extremely stringent requirements on the transmission performance of radio frequency feeder cables. In the high-frequency band above 10 GHz, the insertion loss, phase stability, shielding efficiency, and passive intermodulation (PIM) of the cable directly affect signal quality and system reliability.

[0003] Existing mainstream RF feeder cable technologies have the following shortcomings: (1) Significantly increased high-frequency losses. Existing national standard SYV-50 series and similar RF cables show an exponential increase in attenuation values ​​above 3GHz. According to the classical conductor skin effect theory, conductor loss is proportional to the square root of the frequency, and dielectric loss is proportional to the frequency. In the millimeter-wave band planned for 6G, the attenuation constant of conventional polyethylene foam insulated cables usually exceeds 2.5dB / m, severely compressing the system link budget; (2) The insulation layer has poor foaming uniformity, low closed-cell rate, and uneven distribution of foam cell size, which leads to fluctuations in dielectric constant along the radial and axial directions and a large phase temperature coefficient, making it difficult to meet the requirements of 6G communication for high phase stability. (3) Shielding efficiency deteriorates with increasing frequency. Due to the electromagnetic leakage effect of the braided pores, the shielding effectiveness of conventional single-layer braided shielding structures decreases with increasing frequency at high frequencies, and it is difficult to maintain a shielding efficiency of >90dB in the frequency band above 20GHz. Summary of the Invention

[0004] To address the problems in the prior art, the present invention aims to provide a high-stability, low-loss radio frequency feeder cable for 6G communication and its manufacturing method. By optimizing the material formulations of the insulation layer, intermediate transition layer, and outer sheath layer, and combining structural design and process control, the cable exhibits excellent comprehensive performance in the 10GHz and above frequency bands, making it particularly suitable for 6G communication systems.

[0005] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows: A high-stability, low-loss radio frequency feeder cable for 6G communication, comprising, from the inside out: Inner conductor layer; Insulating layer; First shielding layer; Intermediate transition layer; Second shielding layer; Outer sheath layer; The insulating layer is a blended foam with a foaming degree of 55-65% and a closed-cell rate of ≥90%, and the pore size increases radially from the inside to the outside. The raw materials for preparing the insulating layer include the following components in parts by weight: 100 parts of low-density polytetrafluoroethylene resin; 5-20 parts of low molecular weight polytetrafluoroethylene micro powder; Nucleating agent 0.1~1 part; 1-5 parts of hollow inorganic microspheres; 0.5~3 parts of dielectric constant temperature coefficient compensating filler; 0.5 to 2 parts of foaming agent; The high-stability, low-loss RF feeder cable has a phase temperature coefficient of ≤±10ppm / ℃ within the range of -55℃ to +125℃ and at 10GHz.

[0006] Furthermore, the inner conductor layer is made by 19 silver-plated copper monofilaments arranged in a regular 1+6+12 twisted structure and then compressed. The twisting pitch ratio is 8~12, the compression ratio is 8~12%, the outer diameter after compression is 1.02±0.02mm, the surface roughness Ra≤0.4μm, and the DC resistance ≤18.5Ω / km (20℃).

[0007] Furthermore, the number average molecular weight of the low molecular weight polytetrafluoroethylene micropowder is 1×10⁻⁶. 5 ~5×10 5 Particle size ≤ 5μm; The nucleating agent is at least one of hexagonal boron nitride, nano-silica, and talc, with a particle size ≤500nm; The hollow inorganic microspheres are hollow silica microspheres with an average particle size of 1~3μm and a wall thickness of 0.1~0.3μm; The dielectric constant temperature coefficient compensating filler is at least one of strontium titanate, calcium titanate, and barium titanate, with a particle size ≤1μm, and is surface-treated with a silane coupling agent. The foaming agent is either a physical foaming agent or a chemical foaming agent.

[0008] Furthermore, by weight, the intermediate transition layer is made by stretching and extracting 100 parts of polytetrafluoroethylene dispersion resin and 5-15 parts of extractable pore-forming agent, with a porosity of 30-50% and an average pore size of 0.5-5 μm.

[0009] Furthermore, the extractable pore-forming agent is at least one of calcium carbonate, sodium chloride, and sodium sulfate; Furthermore, the surface of the intermediate transition layer is impregnated with 0.5~2wt% fluorocarbon resin, wherein the fluorocarbon resin is perfluoroethylene propylene or perfluoroalkoxy resin, and after impregnation, it is sintered to form a continuous adhesive layer with a thickness of 0.5~2μm.

[0010] Furthermore, the raw materials for preparing the outer sheath layer include the following components in parts by weight: 100 parts of perfluoroethylene propylene; 0.5-3 parts of nano-silica; 0.5 to 2 parts of polytetrafluoroethylene ultrafine powder.

[0011] Furthermore, the nano-silica particles have a diameter of 20-50 nm and are surface-treated with a silane coupling agent; The polytetrafluoroethylene ultrafine powder has a particle size ≤10μm.

[0012] Furthermore, the first shielding layer is a silver-plated copper strip wrapping layer with a wrapping overlap rate of ≥25% and a silver plating layer thickness of ≥2μm; The second shielding layer is a silver-plated copper wire braided layer with a silver plating thickness of ≥2μm. It is made of 16 spindles × 8 strands / spindle × 0.12mm silver-plated copper wires, with a braiding density of ≥95%, a braiding pitch of ≤18mm, and a braiding angle of 45°~55°.

[0013] This invention also discloses a method for preparing a high-stability, low-loss radio frequency feeder cable for 6G communication, comprising the following steps: S1: 19 silver-plated copper monofilaments are arranged in a regular twisted structure of 1+6+12 and then twisted together. The twisting pitch ratio is 8~12. After twisting, they are compacted and formed. The compaction compression ratio is 8~12%. The outer diameter after compaction is 1.02±0.02mm, the surface roughness Ra≤0.4μm, and the DC resistance≤18.5Ω / km (20℃), thus obtaining the inner conductor layer. S2: By weight, 100 parts of low-density polytetrafluoroethylene resin, 5-20 parts of low molecular weight polytetrafluoroethylene micro powder, 0.1-1 parts of nucleating agent, 1-5 parts of hollow inorganic microspheres, 0.5-3 parts of dielectric constant temperature coefficient compensating filler and 0.5-2 parts of foaming agent are mixed evenly and extruded onto the outer side of the inner conductor layer through an extruder. After sintering and curing, an insulating layer with a foaming degree of 55-65%, a closed-cell rate of ≥90%, and a pore size that increases radially from the inside to the outside is formed. S3: Longitudinally wrap silver-plated copper strip around the outside of the insulation layer, with a wrapping overlap rate of ≥25%, to form the first shielding layer; S4: By weight, 100 parts of polytetrafluoroethylene dispersion resin and 5-15 parts of extractable pore-forming agent are uniformly mixed, stretched to form pores, and the extractable pore-forming agent is removed by extraction to obtain a polytetrafluoroethylene microporous film with a porosity of 30-50% and an average pore size of 0.5-5μm. 0.5-2wt% of fluorocarbon resin solution is impregnated on its surface, and after drying and sintering, it is longitudinally wrapped outside the first shielding layer to form an intermediate transition layer. S5: Silver-plated copper wire is used for high-density braiding outside the intermediate transition layer, with a braiding density ≥95%, a braiding pitch ≤18mm, and a braiding angle of 45°~55° to form a second shielding layer. S6: Extruding a sheath material composed of 100 parts of polytetrafluoroethylene propylene, 0.5-3 parts of nano-silica, and 0.5-2 parts of polytetrafluoroethylene ultrafine powder outside the second shielding layer, finally obtaining the high-stability, low-loss RF feeder cable.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The insulation layer adopts a blended foaming system of low-density PTFE, low molecular weight PTFE micro powder, nucleating agent, hollow inorganic microspheres and dielectric constant temperature coefficient compensating filler, which significantly improves the foaming uniformity and closed-cell rate, makes the foaming cells distributed along the radial gradient, effectively reduces dielectric constant fluctuation, reduces phase temperature coefficient, and improves phase stability performance. 2) The intermediate transition layer is made of PTFE microporous film prepared by extractable pore-forming agent, which has suitable porosity and pore size. It can buffer the thermal expansion difference and mechanical stress between the insulation layer and the shielding layer, and reduce phase drift at high temperature and bending. The surface impregnation with fluorocarbon resin improves the lap bonding strength and ensures structural stability. 3) The outer sheath layer is modified by blending polytetrafluoroethylene with nano-silica and polytetrafluoroethylene ultrafine powder, which improves wear resistance, heat resistance and dimensional stability, while improving the extrusion surface quality and reducing the coefficient of friction, which is beneficial to cable installation and service life. 4) Through the synergistic optimization of formula and structural parameters, the cable has low insertion loss, high return loss, high shielding efficiency, low passive intermodulation, small phase temperature coefficient, and good bending phase stability at 10GHz, meeting the stringent requirements of 6G communication for RF feeder cables. 5) The preparation method of this invention ensures product consistency and performance stability by controlling the foaming process, cooling rate, microporous film overlap and longitudinal wrapping and roll forming; the addition of a phase consistency calibration step controls the phase deviation of the same batch of cable assemblies within ±3°, which is suitable for scenarios requiring high phase consistency such as phased array antennas. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention; Among them, 1-inner conductor layer, 2-insulating layer, 3-first shielding layer, 4-intermediate transition layer, 5-second shielding layer, and 6-outer sheath layer. Detailed Implementation

[0016] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0017] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0018] like Figure 1 As shown, this invention discloses a high-stability, low-loss radio frequency feeder cable for 6G communication, comprising, from the inside out: The inner conductor layer 1 is a silver-plated copper stranded compacted conductor with a stranding pitch ratio of 8~12, an outer diameter of 1.02±0.02mm after compaction, and a surface roughness Ra≤0.4μm; Insulation layer 2 has an outer diameter of 3.05±0.05mm, a dielectric constant of 1.45~1.55, and a loss tangent ≤3.0×10⁻⁶. -4 (@10GHz); The first shielding layer 3 is a silver-plated copper strip wrapping layer with a wrapping overlap rate of ≥25% and a silver plating layer thickness of ≥2μm. Intermediate transition layer 4, with a thickness of 0.10~0.15mm; The second shielding layer 5 is a silver-plated copper wire braided layer with a silver plating thickness of ≥2μm. It is made of 16 spindles × 8 strands / spindle × 0.12mm silver-plated copper wires, with a braiding density of ≥95%, a braiding pitch of ≤18mm, and a braiding angle of 45°~55°. The outer sheath layer 6 has a thickness of 0.50~0.60mm and an outer diameter of 4.65±0.10mm; The cable has a phase temperature coefficient of ≤±10ppm / ℃ within the range of -55~+125℃ and at 10GHz; insertion loss per unit length ≤0.6dB / m and return loss ≥20dB (DC-28GHz) at 10GHz; phase change ≤2°@10GHz under a bending radius of 10 times the cable outer diameter; passive intermodulation PIM3 ≤-165dBc@2×43dBm (1900MHz).

[0019] In some embodiments, the inner conductor layer 1 is made of 19 silver-plated copper monofilaments arranged in a regular 1+6+12 twisted structure and then compressed. The monofilament diameter is 0.20 mm, the compression ratio is 8~12%, the DC resistance is ≤18.5Ω / km (20℃), and the thickness of the silver plating layer of the monofilament is ≥1.5 μm.

[0020] In some embodiments, the insulating layer 2 is a blended foam with a foaming degree of 55-65%, a closed-cell rate of ≥90%, and the pore size increasing radially from the inside to the outside. The raw materials for preparing the insulating layer 2 include the following components in parts by weight: 100 parts of low-density polytetrafluoroethylene resin (low-density PTFE); 5-20 parts of low molecular weight polytetrafluoroethylene micro powder (low molecular weight PTFE micro powder); Nucleating agent 0.1~1 part; 1-5 parts of hollow inorganic microspheres; 0.5~3 parts of dielectric constant temperature coefficient compensating filler; Foaming agent 0.5~2 parts.

[0021] In some specific embodiments, the number average molecular weight of the low molecular weight polytetrafluoroethylene micropowder is 1×10⁻⁶. 5 ~5×10 5 Particle size ≤ 5μm.

[0022] In some specific embodiments, the nucleating agent is at least one of hexagonal boron nitride, nano-silica, and talc, with a particle size ≤500nm.

[0023] In some specific embodiments, the hollow inorganic microspheres are hollow silica microspheres with an average particle size of 1~3μm and a wall thickness of 0.1~0.3μm.

[0024] In some specific embodiments, the dielectric constant temperature coefficient compensation filler is at least one of strontium titanate, calcium titanate, and barium titanate, with a particle size ≤1μm, and is surface-treated with a silane coupling agent.

[0025] In some specific embodiments, the foaming agent is a physical foaming agent or a chemical foaming agent, wherein the physical foaming agent is supercritical CO2 or N2, and the chemical foaming agent is azodicarbonamide.

[0026] In some embodiments, the intermediate transition layer 4 is made by stretching and extracting 100 parts of polytetrafluoroethylene dispersion resin and 5 to 15 parts of extractable pore-forming agent by weight, with a porosity of 30 to 50% and an average pore size of 0.5 to 5 μm.

[0027] In some specific embodiments, the pore-forming agent that can be extracted is at least one of calcium carbonate, sodium chloride, and sodium sulfate.

[0028] In some embodiments, the surface of the intermediate transition layer 4 is impregnated with 0.5 to 2 wt% fluorocarbon resin.

[0029] In some specific embodiments, the fluorocarbon resin is perfluoroethylene propylene or perfluoroalkoxy resin, which is impregnated and then sintered to form a continuous adhesive layer with a thickness of 0.5~2μm.

[0030] In some embodiments, the raw materials for preparing the outer sheath layer 6 include the following components in parts by weight: 100 parts of perfluoroethylene propylene; 0.5-3 parts of nano-silica; 0.5 to 2 parts of polytetrafluoroethylene ultrafine powder.

[0031] In some specific embodiments, the nano-silica particles have a diameter of 20-50 nm and are surface-treated with a silane coupling agent.

[0032] In some specific implementations, the particle size of polytetrafluoroethylene ultrafine powder is ≤10μm.

[0033] This invention also discloses a method for preparing a high-stability, low-loss radio frequency feeder cable for 6G communication, comprising the following steps: S1: Nineteen silver-plated copper monofilaments are arranged in a regular twisted structure of 1+6+12 and then twisted together. The twisting pitch ratio is 8~12. After twisting, they are subjected to compression molding. The compression ratio is 8~12%. The outer diameter after compression is 1.02±0.02mm, the surface roughness Ra≤0.4μm, and the DC resistance≤18.5Ω / km (20℃), thus obtaining the inner conductor layer 1. S2: By weight, 100 parts of low-density polytetrafluoroethylene resin, 5-20 parts of low molecular weight polytetrafluoroethylene micro powder, 0.1-1 parts of nucleating agent, 1-5 parts of hollow inorganic microspheres, 0.5-3 parts of dielectric constant temperature coefficient compensating filler and 0.5-2 parts of foaming agent are mixed evenly and extruded onto the outer side of the inner conductor layer 1 through an extruder. After sintering and curing, an insulating layer 2 with a foaming degree of 55-65%, a closed-cell rate of ≥90%, and a pore size that increases radially from the inside to the outside is formed. S3: A silver-plated copper strip is longitudinally wrapped around the outside of the insulating layer 2, with a wrapping overlap rate of ≥25%, to form the first shielding layer 3; S4: By weight, 100 parts of polytetrafluoroethylene dispersion resin and 5-15 parts of extractable pore-forming agent are uniformly mixed, stretched to form pores, and the extractable pore-forming agent is removed by extraction to obtain a polytetrafluoroethylene microporous film with a porosity of 30-50% and an average pore size of 0.5-5μm. 0.5-2wt% of fluorocarbon resin solution is impregnated on its surface, and after drying and sintering, it is longitudinally wrapped around the first shielding layer 3 to form an intermediate transition layer 4. S5: Silver-plated copper wire is used for high-density braiding outside the intermediate transition layer 4, with a braiding density ≥95%, a braiding pitch ≤18mm, and a braiding angle of 45°~55°, to form the second shielding layer 5. S6: Extruding a sheath material composed of 100 parts of polytetrafluoroethylene propylene, 0.5-3 parts of nano-silica, and 0.5-2 parts of polytetrafluoroethylene ultrafine powder outside the second shielding layer 5, finally obtaining the high-stability, low-loss RF feeder cable.

[0034] In some embodiments, the present invention further includes step S7: for the same batch of cables, a vector network analyzer is used to perform phase consistency calibration at a frequency of 10 GHz, normalizing the phase of the first cable as a reference, and adjusting by comparison to control the phase deviation of the cable assemblies in the same batch within ±3°. Step S7 can be performed or omitted according to actual needs.

[0035] In some implementations, the comparison adjustment involves locally heating or axially micro-stretching / compressing the cable with phase deviation, causing slight plastic deformation of the intermediate transition layer 4 and / or the outer sheath layer 6, changing the local equivalent dielectric constant and electrical length until the phase deviation is ≤ ±3°.

[0036] In some implementations, in step S2, the extrusion temperature is controlled in stages as follows: The temperature ranges from 300 to 320°C in the feeding section, 350 to 360°C in the compression section, 370 to 380°C in the metering section, and 390 to 400°C in the die head. The sintering temperature is 380 to 400°C, and the sintering time is 2 to 3 minutes. After sintering, the temperature is cooled to below 100°C at a rate of 5 to 20°C / min to stabilize the foamed cell structure.

[0037] In some embodiments, in step S4, the polytetrafluoroethylene microporous film is longitudinally wrapped with an overlap rate of 10-20%. After longitudinal wrapping, it is heated with hot air at 80-120°C to make the overlap slightly melt and bond together, forming a closed sleeve.

[0038] In some embodiments, after weaving in step S5, the second shielding layer 5 is rolled and shaped so that the outer diameter tolerance of the second shielding layer 5 is ≤ ±0.05mm and the weaving angle is maintained at 45°~55°.

[0039] Example 1

[0040] like Figure 1 As shown, a high-stability, low-loss radio frequency feeder cable for 6G communication comprises, from the inside out: The inner conductor layer 1 is made of 19 silver-plated copper monofilaments arranged in a regular 1+6+12 twisted structure and then compressed. The monofilament diameter is 0.20 mm, the twisting pitch ratio is 10, the compression ratio is 10%, the outer diameter after compression is 1.02 mm, the surface roughness Ra is 0.3 μm, the DC resistance is 18 Ω / km (20℃), and the thickness of the silver plating layer on the monofilament is 2 μm. Insulating layer 2 has an outer diameter of 3.05 mm, a dielectric constant of 1.5, and a loss tangent of 2.5 × 10⁻⁶. -4 (@10GHz); The first shielding layer 3 is a silver-plated copper strip wrapping layer with a wrapping overlap rate of 30% and a silver plating layer thickness of 2μm. Intermediate transition layer 4, with a thickness of 0.12 mm; The second shielding layer 5 is a silver-plated copper wire braided layer with a silver plating thickness of 2μm. It is made of 16 spindles × 8 strands / spindle × 0.12mm silver-plated copper wires, with a braiding density of 95%, a braiding pitch of 16mm, and a braiding angle of 50°. The outer sheath layer 6 has a thickness of 0.50 mm and an outer diameter of 4.65 mm.

[0041] The insulating layer 2 is a blended foam with a foaming degree of 60%, a closed-cell rate of 95%, an average pore diameter of 6μm, and the pore diameter increases radially from the inside to the outside.

[0042] The raw materials for preparing insulating layer 2 include the following components in parts by weight: Low-density polytetrafluoroethylene resin (low-density PTFE, number average molecular weight 8×10⁻⁶) 6 100 copies; Low molecular weight polytetrafluoroethylene micro powder (low molecular weight PTFE micro powder, number average molecular weight of 3×10) 5 12 portions (particle size 3μm); 0.5 parts of hexagonal boron nitride nucleating agent; Three portions of hollow silica microspheres (average particle size 2 μm, wall thickness 0.2 μm); 1.5 parts of strontium titanate filler (particle size 0.8 μm, and surface treated with silane coupling agent); One part of azodicarbonamide foaming agent.

[0043] By weight, the intermediate transition layer 4 is made of 100 parts polytetrafluoroethylene dispersion resin and 10 parts calcium carbonate through stretching and extraction, with a porosity of 40% and an average pore size of 2 μm.

[0044] The intermediate transition layer 4 is impregnated with 1 wt% fluorocarbon resin, which is polytetrafluoroethylene propylene resin. After impregnation, it is sintered to form a continuous adhesive layer with a thickness of 1 μm.

[0045] The raw materials for preparing the outer sheath layer 6 include the following components in parts by weight: 100 parts of perfluoroethylene propylene; 1.5 parts of nano-silica (30nm particle size, treated with silane coupling agent); One part of polytetrafluoroethylene ultrafine powder (particle size 5μm).

[0046] A method for manufacturing a high-stable-phase, low-loss radio frequency feeder cable for 6G communication includes the following steps: S1: 19 silver-plated copper monofilaments are arranged in a regular twisted structure of 1+6+12 and twisted together with a twisting pitch ratio of 10. After twisting, they are subjected to compression molding with a compression ratio of 10%. The outer diameter after compression is 1.02 mm, the surface roughness Ra is 0.3 μm, and the DC resistance is 18 Ω / km (20℃), thus obtaining the inner conductor layer 1. S2: By weight, 100 parts of low-density polytetrafluoroethylene resin, 12 parts of low molecular weight polytetrafluoroethylene micro powder, 0.5 parts of hexagonal boron nitride nucleating agent, 3 parts of hollow inorganic microspheres, 1.5 parts of dielectric constant temperature coefficient compensating filler and 1 part of azodicarbonamide foaming agent are mixed evenly and extruded onto the outer side of the inner conductor layer 1 through an extruder. After sintering and curing, an insulating layer 2 with a foaming degree of 60%, a closed-cell rate of 95%, and a pore size that increases radially from the inside to the outside is formed. S3: A silver-plated copper strip is longitudinally wrapped around the outside of the insulating layer 2, with a wrapping overlap rate of 30%, to form the first shielding layer 3; S4: By weight, 100 parts of polytetrafluoroethylene dispersion resin and 10 parts of calcium carbonate are uniformly mixed, stretched to form pores, and extracted to remove the extractable pore-forming agent to obtain a polytetrafluoroethylene microporous film with a porosity of 40% and an average pore size of 2μm. 1 wt% of polytetrafluoroethylene propylene resin solution is impregnated on its surface, and after drying and sintering, it is longitudinally wrapped around the first shielding layer 3 to form an intermediate transition layer 4. S5: Silver-plated copper wire is used for high-density braiding outside the intermediate transition layer 4, with a braiding density of 95%, a braiding pitch of 16mm, and a braiding angle of 50°, to form the second shielding layer 5. S6: Extruding a sheath material composed of 100 parts of polytetrafluoroethylene propylene, 1.5 parts of nano-silica, and 1 part of polytetrafluoroethylene ultrafine powder outside the second shielding layer 5, finally obtaining the high-stability, low-loss RF feeder cable.

[0047] In step S2, the extrusion temperature is controlled in segments as follows: The feeding section is 320℃, the compression section is 360℃, the metering section is 380℃, the die head temperature is 400℃, the sintering temperature is 380℃, the sintering time is 3min, and after sintering, it is cooled to below 100℃ at a rate of 5℃ / min to stabilize the foamed cell structure.

[0048] In step S4, the polytetrafluoroethylene microporous film is longitudinally wrapped with an overlap rate of 15%. After longitudinal wrapping, it is heated with hot air at 100°C to make the overlap slightly melt and bond together, forming a closed sleeve.

[0049] After weaving in step S5, the second shielding layer 5 is rolled and shaped to ensure that the outer diameter tolerance of the second shielding layer 5 is ≤ ±0.05mm and the weaving angle is maintained at 50°.

[0050] The performance of the cable in Example 1 was tested, and the results are as follows: The phase temperature coefficient of the cable at 10 GHz within the range of -55 to +125°C is ±8 ppm / °C. Insertion loss per unit length at 10GHz: 0.58dB / m, return loss: 22dB (DC-28GHz). With a bending radius of 10 times the cable outer diameter, the phase change is 1.82°@10GHz; Passive intermodulation PIM3: -168dBc@2×43dBm (1900MHz); Shielding efficiency: 115dB (DC-28GHz); Transfer impedance: 8mΩ / m@1GHz.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that the insulation layer in this comparative example is foamed with pure low-density polytetrafluoroethylene resin, without the addition of low molecular weight PTFE micropowder, nucleating agent, hollow inorganic microspheres, dielectric constant temperature coefficient compensating filler, and foaming agent. The rest is the same as in Example 1.

[0052] Test results for Comparative Example 1: The phase temperature coefficient of the cable at 10 GHz within the range of -55 to +125 ℃ is ±18 ppm / ℃. Insertion loss per unit length at 10 GHz: 0.65 dB / m; With a bending radius of 10 times the cable outer diameter, the phase change is 4.5°@10GHz; Passive intermodulation PIM3: -155dBc@2×43dBm (1900MHz).

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that the intermediate transition layer in this comparative example uses a solid PTFE film (non-porous). Everything else is the same as in Example 1.

[0054] Test results for Comparative Example 2: Significant phase drift occurs at high temperatures (+125℃), with a phase temperature coefficient of ±15ppm / ℃ at 10GHz and a bending phase change of 3.8°@10GHz.

[0055] Comparative Example 3 The difference between this comparative example and Example 1 is that the outer sheath layer of this comparative example is made of pure perfluoroethylene propylene, without the addition of nano-silica and polytetrafluoroethylene ultrafine powder. The rest is the same as in Example 1.

[0056] Test results for Comparative Example 3: It has poor wear resistance, a high surface friction coefficient, is easily damaged during installation, and its long-term reliability decreases.

[0057] The results above show that only by adopting the layer structure and corresponding formulation of this invention can a high-stability, low-loss RF feeder cable for 6G communication be obtained. Moreover, it is superior to the comparative example in terms of insertion loss, phase stability, shielding performance, and passive intermodulation, thus meeting the high-performance requirements of RF feeder cables for the high-frequency band of 6G communication.

[0058] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0059] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-stability, low-loss radio frequency feeder cable for 6G communication, characterized in that, From the inside out, it includes: Inner conductor layer; Insulating layer; First shielding layer; Intermediate transition layer; Second shielding layer; Outer sheath layer; The insulating layer is a blended foam with a foaming degree of 55-65% and a closed-cell rate of ≥90%, and the pore size increases radially from the inside to the outside. The raw materials for preparing the insulating layer include the following components in parts by weight: 100 parts of low-density polytetrafluoroethylene resin; 5-20 parts of low molecular weight polytetrafluoroethylene micro powder; Nucleating agent 0.1~1 part; 1-5 parts of hollow inorganic microspheres; 0.5 to 3 parts of dielectric constant temperature coefficient compensating filler; 0.5 to 2 parts of foaming agent; The high-stability, low-loss RF feeder cable has a phase temperature coefficient of ≤±10ppm / ℃ within the range of -55℃ to +125℃ and at 10GHz.

2. The high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1, characterized in that, The inner conductor layer is made of 19 silver-plated copper monofilaments arranged in a regular 1+6+12 twisted structure and then compressed. The twisting pitch ratio is 8~12, the compression ratio is 8~12%, the outer diameter after compression is 1.02±0.02mm, the surface roughness Ra≤0.4μm, and the DC resistance ≤18.5Ω / km (20℃).

3. The high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1, characterized in that, The number average molecular weight of the low molecular weight polytetrafluoroethylene micropowder is 1×10⁻⁶. 5 ~5×10 5 Particle size ≤ 5μm; The nucleating agent is at least one of hexagonal boron nitride, nano-silica, and talc, with a particle size ≤500nm; The hollow inorganic microspheres are hollow silica microspheres with an average particle size of 1~3μm and a wall thickness of 0.1~0.3μm; The dielectric constant temperature coefficient compensating filler is at least one of strontium titanate, calcium titanate, and barium titanate, with a particle size ≤1μm, and is surface-treated with a silane coupling agent.

4. The high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1, characterized in that, By weight, the intermediate transition layer is made of 100 parts polytetrafluoroethylene dispersion resin and 5-15 parts extractable pore-forming agent through stretching and extraction, with a porosity of 30-50% and an average pore size of 0.5-5 μm.

5. A high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 4, characterized in that, The extractable pore-forming agent is at least one of calcium carbonate, sodium chloride, and sodium sulfate.

6. A high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1 or 4, characterized in that, The intermediate transition layer is impregnated with 0.5-2 wt% fluorocarbon resin, which is perfluoroethylene propylene or perfluoroalkoxy resin. After impregnation, it is sintered to form a continuous adhesive layer with a thickness of 0.5-2 μm.

7. A high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1, characterized in that, The raw materials for preparing the outer sheath layer include the following components in parts by weight: 100 parts of perfluoroethylene propylene; 0.5-3 parts of nano-silica; 0.5 to 2 parts of polytetrafluoroethylene ultrafine powder.

8. A high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 7, characterized in that, The nano-silica particles have a diameter of 20-50 nm and are surface-treated with a silane coupling agent. The polytetrafluoroethylene ultrafine powder has a particle size ≤10μm.

9. A high-stability, low-loss radio frequency feeder cable for 6G communication according to claim 1, characterized in that, The first shielding layer is a silver-plated copper strip wrapping layer with a wrapping overlap rate of ≥25% and a silver plating layer thickness of ≥2μm; The second shielding layer is a silver-plated copper wire braided layer with a silver plating thickness of ≥2μm. It is made of 16 spindles × 8 strands / spindle × 0.12mm silver-plated copper wires, with a braiding density of ≥95%, a braiding pitch of ≤18mm, and a braiding angle of 45°~55°.

10. A method for preparing a high-stability, low-loss radio frequency feeder cable for 6G communication according to any one of claims 1-9, characterized in that, Includes the following steps: S1: 19 silver-plated copper monofilaments are arranged in a regular twisted structure of 1+6+12 and then twisted together. The twisting pitch ratio is 8~12. After twisting, they are compacted and formed. The compaction compression ratio is 8~12%. The outer diameter after compaction is 1.02±0.02mm, the surface roughness Ra≤0.4μm, and the DC resistance≤18.5Ω / km (20℃), thus obtaining the inner conductor layer. S2: By weight, 100 parts of low-density polytetrafluoroethylene resin, 5-20 parts of low molecular weight polytetrafluoroethylene micro powder, 0.1-1 parts of nucleating agent, 1-5 parts of hollow inorganic microspheres, 0.5-3 parts of dielectric constant temperature coefficient compensating filler and 0.5-2 parts of foaming agent are mixed evenly and extruded onto the outer side of the inner conductor layer through an extruder. After sintering and curing, an insulating layer with a foaming degree of 55-65%, a closed-cell rate of ≥90%, and a pore size that increases radially from the inside to the outside is formed. S3: Longitudinally wrap silver-plated copper strip around the outside of the insulation layer, with a wrapping overlap rate of ≥25%, to form the first shielding layer; S4: By weight, 100 parts of polytetrafluoroethylene dispersion resin and 5-15 parts of extractable pore-forming agent are uniformly mixed, stretched to form pores, and the extractable pore-forming agent is removed by extraction to obtain a polytetrafluoroethylene microporous film with a porosity of 30-50% and an average pore size of 0.5-5μm. 0.5-2wt% of fluorocarbon resin solution is impregnated on its surface, and after drying and sintering, it is longitudinally wrapped outside the first shielding layer to form an intermediate transition layer. S5: Silver-plated copper wire is used for high-density braiding outside the intermediate transition layer, with a braiding density ≥95%, a braiding pitch ≤18mm, and a braiding angle of 45°~55° to form a second shielding layer. S6: Extruding a sheath material composed of 100 parts of polytetrafluoroethylene propylene, 0.5-3 parts of nano-silica, and 0.5-2 parts of polytetrafluoroethylene ultrafine powder outside the second shielding layer, finally obtaining the high-stability, low-loss RF feeder cable.

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