Low-frequency intermodulation leaky coaxial cable based on asymmetric slot design

Abstract

The invention discloses a low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design, and relates to the field of cables, the low-frequency intermodulation leaky coaxial cable comprises a cable body, a seven-core stranded silver-coated copper wire is installed in an inner cavity of the cable body, a gradient insulating layer is installed on the outer wall of the cable body, a composite outer conductor is installed on the outer wall of the gradient insulating layer, and the composite outer conductor is connected with a cable core. And a multi-layer sheath is arranged on the outer wall of the composite outer conductor. According to the low-frequency intermodulation leaky coaxial cable based on the asymmetric slotted hole design, the periodic structure characteristic of a traditional leaky coaxial cable is thoroughly broken through through the full-penetrating four-dimensional gradual change slotted holes and the semi-penetrating four-dimensional gradual change slotted holes which are asymmetrically arranged; the width, the depth and the arrangement density of the full-penetrating four-dimensional gradually-changing slot holes and the semi-penetrating four-dimensional gradually-changing slot holes are gradually changed, so that electromagnetic waves cannot form standing waves and resonance at a specific frequency, a generation path of an intermodulation product is fundamentally cut off, excessive concentration of energy in a local area can be avoided, and the nonlinear effect is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of cables, and particularly to a low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design. Background Art

[0002] A leaky coaxial cable has the function of signal transmission and the function of an antenna. By controlling the opening of the outer conductor, the controlled electromagnetic wave energy can be evenly radiated out and received along the line, realizing the coverage of the electromagnetic field blind area and achieving the purpose of smooth mobile communication.

[0003] Traditional leaky cables adopt a periodic symmetric slot structure, resulting in significant high-frequency intermodulation products, and at the same time having three major defects: periodic symmetric arrangement causes resonant intermodulation; linear slots lead to uneven electromagnetic field distribution; a single material outer conductor generates non-linear effects.

[0004] Therefore, it is necessary to propose a low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design to solve the above problems. Summary of the Invention

[0005] The main object of the present invention is to provide a low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design, which can effectively solve the problems in the background art.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design, including a cable body. A seven-core stranded silver-clad copper wire is installed in the inner cavity of the cable body. A gradient insulating layer is installed on the outer wall of the cable body. A composite outer conductor is installed on the outer wall of the gradient insulating layer. A multi-layer sheath is installed on the outer wall of the composite outer conductor;

[0008] A main spiral band and a sub-spiral band are installed on the outer wall of the composite outer conductor. A fully penetrating four-dimensional gradient slot is opened on the outer wall of the main spiral band. A semi-penetrating four-dimensional gradient slot is opened on the outer wall of the sub-spiral band.

[0009] Preferably, the gradient insulating layer includes foamed polyethylene, fluororesin and ceramic powder doped PE. The foaming degree of the foamed polyethylene is 80%, ε = 1.3; the fluororesin ε = 2.1, the thickness is 0.2 mm, and the ceramic powder doped PE ε = 3.4, the thickness is 0.15 mm.

[0010] Preferably, the composite outer conductor includes a nanocrystalline layer, a transition layer, and a topological insulating layer. The nanocrystalline layer is a Fe-Si-B amorphous alloy with a thickness of 50 μm and a grain size of ≤20 nm; the transition layer is an Ag gradient coating with an Ag content of 80% → 30%; the topological insulating layer is a Bi2Te3 and SiC composite material with a thickness of 0.1 mm, and the thickness of the composite outer conductor is 0.3 mm.

[0011] Preferably, the multi-layer sheath includes a conductive graphite layer, an electromagnetic shielding layer, and a flame-retardant outer layer. The conductive graphite layer has a thickness of 50 μm and a surface resistance of ≤1 Ω / sq; the electromagnetic shielding layer is woven from 144 silver-plated copper wires with a braiding angle of 45° and a coverage rate of ≥96%, and the flame-retardant outer layer is a low-smoke and halogen-free material with an oxygen index of ≥3.

[0012] Preferably, the main spiral band is left-handed, the secondary spiral band is right-handed, the main spiral band and the secondary spiral band cross each other, both the fully-penetrating four-dimensional gradually-varying slot hole and the semi-penetrating four-dimensional gradually-varying slot hole penetrate the composite outer conductor, the fully-penetrating four-dimensional gradually-varying slot hole fully penetrates the composite outer conductor, the semi-penetrating four-dimensional gradually-varying slot hole semi-penetrates the composite outer conductor, and the fully-penetrating four-dimensional gradually-varying slot hole and the semi-penetrating four-dimensional gradually-varying slot hole are used to form a stepped impedance.

[0013] Preferably, along the length direction of the cable body, the widths of the fully-penetrating four-dimensional gradually-varying slot hole and the semi-penetrating four-dimensional gradually-varying slot hole change according to a piecewise function: in the first one-third section, it linearly increases by 0.5 - 1.2 mm, in the middle one-third section, it exponentially increases by 1.2 - 1.8 mm, and in the last one-third section, it is polynomial-fitted by 1.8 - 2.2 mm.

[0014] Preferably, chamfers with a width of 0.05 - 0.1 mm are provided on the inner walls of the fully-penetrating four-dimensional gradually-varying slot hole and the semi-penetrating four-dimensional gradually-varying slot hole, the inlet width of the chamfer is greater than the outlet width, the fully-penetrating four-dimensional gradually-varying slot hole penetrates the composite outer conductor by 0.3 mm, the semi-penetrating four-dimensional gradually-varying slot hole penetrates the composite outer conductor by 0.2 mm, and the number of slot holes per unit length of the fully-penetrating four-dimensional gradually-varying slot hole and the semi-penetrating four-dimensional gradually-varying slot hole increases from 5 per m to 8 per m with a step size of 0.3 per m.

[0015] Preferably, six of the phase interference slots form a group, and a group of the phase interference slots form a regular hexagonal array.

[0016] Preferably, dumbbell holes and circular grooves are provided at the cross of the main spiral band and the secondary spiral band, the ratio of the dumbbell holes to the circular grooves is 3:1, and serrated corrugations with an amplitude of 0.02 mm and a period of 0.1 mm are provided at the edges of the dumbbell holes and the circular grooves.

[0017] Preferably, the fully penetrating four-dimensional gradient slot holes are distributed at the main spiral band, and the semi-penetrating four-dimensional gradient slot holes are distributed at the secondary spiral band, which are used to form an electromagnetic shielding grid with depth staggering with the fully penetrating four-dimensional gradient slot holes at the main spiral band.

[0018] Compared with the prior art, the present invention provides a low-frequency intermodulation leakage coaxial cable based on an asymmetric slot hole design, which has the following beneficial effects:

[0019] 1. For the low-frequency intermodulation leakage coaxial cable based on the asymmetric slot hole design, through the fully penetrating four-dimensional gradient slot holes and semi-penetrating four-dimensional gradient slot holes arranged asymmetrically, the periodic structural characteristics of the traditional leakage coaxial cable are completely broken. The gradient changes of the fully penetrating four-dimensional gradient slot holes and semi-penetrating four-dimensional gradient slot holes in width, depth, and arrangement density make it impossible for electromagnetic waves to form standing waves and resonances at specific frequencies, fundamentally cutting off the generation path of intermodulation products. Especially in a complex electromagnetic environment with coexistence of multiple frequency bands, this structure can adaptively disperse electromagnetic energy, avoid excessive concentration of energy in local areas, and thus significantly reduce the nonlinear effect.

[0020] 2. For the low-frequency intermodulation leakage coaxial cable based on the asymmetric slot hole design, through the main spiral band and secondary spiral band provided, the radiation path of electromagnetic waves changes from traditional linear propagation to multi-path scattering. The fully penetrating four-dimensional gradient slot holes, semi-penetrating four-dimensional gradient slot holes, dumbbell holes, and circular grooves at the main spiral band and secondary spiral band can guide the uniform diffusion of electromagnetic waves at different scales, and the double spiral trajectories of the main spiral band and secondary spiral band form a distribution pattern similar to electromagnetic eddy currents through the interference effect of left-handed and right-handed rotations. This synergistic effect not only improves the uniformity of signal coverage but also can automatically adjust the radiation direction angle according to the environment, reducing signal blind spots.

[0021] 3. For the low-frequency intermodulation leakage coaxial cable based on the asymmetric slot hole design, through the combined design of dumbbell holes, circular grooves, and composite outer conductors, the balance between strength and flexibility is achieved in the physical structure. The alternating layout of dumbbell holes and circular grooves disperses the stress concentration points, enabling the cable body to maintain the integrity of the slot hole shape during bending and torsion; through the combination of a gradient insulating layer, composite outer conductor, and multi-layer sheath, the environmental corrosion such as humidity and salt spray can be effectively resisted. Even in harsh working conditions such as tunnels and the seabed, the cable body can still work stably for a long time without frequent maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the schematic structural diagram of the whole of the present invention;

[0023] Figure 2 is the cross-sectional view of the present invention;

[0024] Figure 3 is the present invention Figure 2Enlarged view of part A

[0025] Figure 4 is a schematic structural view of the composite outer conductor of the present invention;

[0026] Figure 5 is a schematic structural view of the fully penetrating four-dimensional gradient slot hole of the present invention.

[0027] In the figure: 1. Cable body; 2. Seven-core stranded silver-clad copper wire; 3. Gradient insulating layer; 4. Composite outer conductor; 5. Multilayer sheath; 6. Foamed polyethylene; 7. Fluororesin; 8. PE doped with ceramic powder; 9. Nanocrystalline layer; 10. Transition layer; 11. Topological insulating layer; 12. Conductive graphite layer; 13. Electromagnetic shielding layer; 14. Flame-retardant outer layer; 15. Main spiral band; 16. Sub-spiral band; 17. Semi-penetrating four-dimensional gradient slot hole; 18. Dumbbell hole; 19. Round groove; 20. Phase interference slot; 21. Fully penetrating four-dimensional gradient slot hole. Detailed implementation modes

[0028] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation modes.

[0029] Example 1:

[0030] As shown in Figures 1-3 , a low-frequency intermodulation leaky coaxial cable based on an asymmetric slot hole design includes a cable body 1. A seven-core stranded silver-clad copper wire 2 is installed in the inner cavity of the cable body 1. A gradient insulating layer 3 is installed on the outer wall of the cable body 1. A composite outer conductor 4 is installed on the outer wall of the gradient insulating layer 3. A multilayer sheath 5 is installed on the outer wall of the composite outer conductor 4. The gradient insulating layer 3 includes foamed polyethylene 6, fluororesin 7 and PE doped with ceramic powder 8. The foaming degree of the foamed polyethylene 6 is 80%, ε = 1.3; the fluororesin 7 has ε = 2.1 and a thickness of 0.2 mm, and the PE doped with ceramic powder 8 has ε = 3.4 and a thickness of 0.15 mm. The composite outer conductor 4 includes a nanocrystalline layer 9, a transition layer 10 and a topological insulating layer 11. The nanocrystalline layer 9 is an Fe-Si-B amorphous alloy with a thickness of 50 μm and a grain size ≤ 20 nm; the transition layer 10 is an Ag gradient coating with an Ag content of 80% → 30%; the topological insulating layer 11 is a Bi2Te3 and SiC composite material with a thickness of 0.1 mm. The multilayer sheath 5 includes a conductive graphite layer 12, an electromagnetic shielding layer 13 and a flame-retardant outer layer 14. The conductive graphite layer 12 has a thickness of 50 μm and a surface resistance ≤ 1 Ω / sq; the electromagnetic shielding layer 13 is woven from 144 silver-plated copper wires with a braiding angle of 45° and a coverage rate ≥ 96%. The flame-retardant outer layer 14 is a low-smoke and halogen-free material with an oxygen index ≥ 3.

[0031] Example 2:

[0032] As shown in Figure 1, Figure 4 , Figure 5 As shown in Figure 4 and Figure 5 , a low-frequency intermodulation leakage coaxial cable based on an asymmetric slot design. A main spiral band 15 and a secondary spiral band 16 are installed on the outer wall of the composite outer conductor 4. A fully penetrating four-dimensional gradient slot 21 is opened on the outer wall of the main spiral band 15, and a semi-penetrating four-dimensional gradient slot 17 is opened on the outer wall of the secondary spiral band 16. The main spiral band 15 is a left-handed spiral, and the secondary spiral band 16 is a right-handed spiral. The main spiral band 15 and the secondary spiral band 16 cross each other. Both the fully penetrating four-dimensional gradient slot 21 and the semi-penetrating four-dimensional gradient slot 17 penetrate the composite outer conductor 4. The fully penetrating four-dimensional gradient slot 21 fully penetrates the composite outer conductor 4, and the semi-penetrating four-dimensional gradient slot 17 semi-penetrates the composite outer conductor 4. The fully penetrating four-dimensional gradient slot 21 and the semi-penetrating four-dimensional gradient slot 17 are used to form a stepped impedance. Along the length direction of the cable body 1, the slot width of the fully penetrating four-dimensional gradient slot 21 and the semi-penetrating four-dimensional gradient slot 17 changes according to a piecewise function: it linearly increases by 0.5 - 1.2 mm in the first one-third section, exponentially increases by 1.2 - 1.8 mm in the middle one-third section, and is polynomial-fitted by 1.8 - 2.2 mm in the last one-third section. A chamfer with a width of 0.05 - 0.1 mm is opened on the inner wall of the fully penetrating four-dimensional gradient slot 21 and the semi-penetrating four-dimensional gradient slot 17. The entrance width of the chamfer is greater than the exit width. The fully penetrating four-dimensional gradient slot 21 penetrates the composite outer conductor 4 by 0.3 mm, and the semi-penetrating four-dimensional gradient slot 17 penetrates the composite outer conductor 4 by 0.2 mm. The number of slots per unit length of the fully penetrating four-dimensional gradient slot 21 and the semi-penetrating four-dimensional gradient slot 17 increases from 5 slots / m to 8 slots / m with a step of 0.3 slots / m. Six phase interference slots 20 form a group, and a group of phase interference slots 20 form a regular hexagonal array. A dumbbell hole 18 and a circular groove 19 are opened at the intersection of the main spiral band 15 and the secondary spiral band 16. The ratio of the dumbbell hole 18 to the circular groove 19 is 3:1. Serrated corrugations with an amplitude of 0.02 mm and a period of 0.1 mm are provided at the edges of the dumbbell hole 18 and the circular groove 19. The fully penetrating four-dimensional gradient slot 21 is distributed at the main spiral band 15, and the semi-penetrating four-dimensional gradient slot 17 is distributed at the secondary spiral band 16, which is used to form a deeply staggered electromagnetic shielding grid with the fully penetrating four-dimensional gradient slot 21 at the main spiral band 15.

[0033] Through the asymmetrically arranged fully penetrating four-dimensional gradient slots 21 and semi-penetrating four-dimensional gradient slots 17, the periodic structural characteristics of traditional leaky coaxial cables are completely broken. The gradient changes in width, depth, and arrangement density of the fully penetrating four-dimensional gradient slots 21 and semi-penetrating four-dimensional gradient slots 17 prevent electromagnetic waves from forming standing waves and resonances at specific frequencies, fundamentally cutting off the generation path of intermodulation products. Especially in a complex electromagnetic environment with multi-band coexistence, this structure can adaptively disperse electromagnetic energy, avoid excessive energy concentration in local areas, and thus significantly reduce the nonlinear effect. By setting the main helical band 15 and the secondary helical band 16, the radiation path of electromagnetic waves changes from traditional linear propagation to multi-path scattering. The fully penetrating four-dimensional gradient slots 21, semi-penetrating four-dimensional gradient slots 17, dumbbell holes 18, and circular grooves 19 at the main helical band 15 and the secondary helical band 16 can guide the uniform diffusion of electromagnetic waves at different scales. The double helical trajectories of the main helical band 15 and the secondary helical band 16 form a distribution pattern similar to an electromagnetic eddy through the interference effect of left-handed and right-handed rotations. This synergistic effect not only improves the uniformity of signal coverage but also can automatically adjust the radiation direction angle according to the environment, reducing signal blind spots. Through the combined design of the dumbbell holes 18, circular grooves 19, and composite outer conductor 4, the balance between strength and flexibility is achieved in the physical structure. The alternating layout of the dumbbell holes 18 and circular grooves 19 disperses the stress concentration points, enabling the cable body 1 to maintain the integrity of the slot shape during bending and torsion. Through the combination of the gradient insulating layer 3, composite outer conductor 4, and multi-layer sheath 5, the cable can effectively resist environmental corrosion such as humidity and salt spray. Even in harsh working conditions such as tunnels and the seabed, the cable body 1 can still operate stably for a long time without frequent maintenance.

[0034] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design, comprising a cable body (1), characterized in that: A seven-core stranded silver-clad copper wire (2) is installed in the inner cavity of the cable body (1). A gradient insulation layer (3) is installed on the outer wall of the cable body (1). A composite outer conductor (4) is installed on the outer wall of the gradient insulation layer (3). A multi-layer sheath (5) is installed on the outer wall of the composite outer conductor (4); A main helical band (15) and a secondary helical band (16) are installed on the outer wall of the composite outer conductor (4). A fully penetrating four-dimensional gradient slot hole (21) is opened on the outer wall of the main helical band (15). A semi-penetrating four-dimensional gradient slot hole (17) is opened on the outer wall of the secondary helical band (16).

2. The low-frequency intermodulation leaky coaxial cable based on the asymmetric slot design according to claim 1, wherein: The gradient insulation layer (3) includes foamed polyethylene (6), fluororesin (7), and ceramic powder-doped PE (8). The foamed polyethylene (6) has a foaming degree of 80% and ε = 1.3; the fluororesin (7) has ε = 2.1 and a thickness of 0.2 mm, and the ceramic powder-doped PE (8) has ε = 3.4 and a thickness of 0.15 mm.

3. An asymmetric slot design-based low-frequency intermodulation leaky coaxial cable according to claim 1, characterized in that: The composite outer conductor (4) includes a nanocrystalline layer (9), a transition layer (10), and a topological insulation layer (11). The nanocrystalline layer (9) is an Fe-Si-B amorphous alloy with a thickness of 50 μm and a grain size ≤ 20 nm; the transition layer (10) is an Ag gradient coating with an Ag content of 80% → 30%; the topological insulation layer (11) is a Bi2Te3 and SiC composite material with a thickness of 0.1 mm, and the thickness of the composite outer conductor (4) is 0.3 mm.

4. An asymmetric slot design-based low-frequency intermodulation leaky coaxial cable according to claim 1, characterized in that: The multi-layer sheath (5) includes a conductive graphite layer (12), an electromagnetic shielding layer (13), and a flame-retardant outer layer (14). The conductive graphite layer (12) has a thickness of 50 μm and a surface resistance ≤ 1 Ω / sq; the electromagnetic shielding layer (13) is woven from 144 silver-plated copper wires with a weaving angle of 45° and a coverage rate ≥ 96%, and the flame-retardant outer layer (14) is a low-smoke and halogen-free material with an oxygen index ≥ 3.

5. The low-frequency intermodulation leaky coaxial cable based on the asymmetric slot design according to claim 1, wherein: The main helical band (15) is a left helix, the secondary helical band (16) is a right helix, the main helical band (15) and the secondary helical band (16) cross each other. The fully penetrating four-dimensional gradient slot hole (21) and the semi-penetrating four-dimensional gradient slot hole (17) both penetrate the composite outer conductor (4). The fully penetrating four-dimensional gradient slot hole (21) fully penetrates the composite outer conductor (4), and the semi-penetrating four-dimensional gradient slot hole (17) semi-penetrates the composite outer conductor (4). The fully penetrating four-dimensional gradient slot hole (21) and the semi-penetrating four-dimensional gradient slot hole (17) are used to form a stepped impedance.

6. The low-frequency intermodulation leaky coaxial cable based on the asymmetric slot design according to claim 1, wherein: The fully penetrating four-dimensional gradient slot hole (21) and the semi-penetrating four-dimensional gradient slot hole (17) are along the length direction of the cable body (1), and the slot width changes according to a piecewise function: in the first one-third section, it linearly increases from 0.5 - 1.2 mm, in the middle one-third section, it exponentially increases from 1.2 - 1.8 mm, and in the last one-third section, it is polynomially fitted from 1.8 - 2.2 mm.

7. An asymmetric slot design-based low-frequency intermodulation leaky coaxial cable according to claim 6, characterized in that: The inner walls of the fully penetrating four-dimensional gradient slot holes (21) and the semi-penetrating four-dimensional gradient slot holes (17) are provided with chamfers of 0.05 - 0.1 mm. The inlet width of the chamfers is greater than the outlet width. The fully penetrating four-dimensional gradient slot holes (21) penetrate through the composite outer conductor (4) by 0.3 mm, and the semi-penetrating four-dimensional gradient slot holes (17) penetrate through the composite outer conductor (4) by 0.2 mm. The number of slot holes per unit length of the fully penetrating four-dimensional gradient slot holes (21) and the semi-penetrating four-dimensional gradient slot holes (17) increases from 5 per meter to 8 per meter, with a step size of 0.3 per meter.

8. An asymmetric slot design-based low-frequency intermodulation leaky coaxial cable according to claim 1, characterized in that: Six of the phase interference slots (20) form a group, and a group of the phase interference slots (20) form a regular hexagonal array.

9. An asymmetric slot design-based low-frequency intermodulation leaky coaxial cable according to claim 1, characterized in that: Dumbbell holes (18) and circular grooves (19) are provided at the intersections of the main spiral band (15) and the secondary spiral band (16). The ratio of the dumbbell holes (18) to the circular grooves (19) is 3:

1. Serrated corrugations with an amplitude of 0.02 mm and a period of 0.1 mm are provided at the edges of the dumbbell holes (18) and the circular grooves (19).

10. A low-frequency intermodulation leaky coaxial cable based on an asymmetric slot design according to claim 1, characterized in that: The fully penetrating four-dimensional gradient slot holes (21) are distributed at the main spiral band (15), and the semi-penetrating four-dimensional gradient slot holes (17) are distributed at the secondary spiral band (16) to form an electromagnetic shielding grid with deep staggering with the fully penetrating four-dimensional gradient slot holes (21) at the main spiral band (15).

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