Leaky coaxial cable for industrial wireless coverage

Abstract

The utility model discloses a leaky coaxial cable for industrial wireless coverage, which is characterized in that slotted hole groups are periodically arranged on an outer conductor, each slotted hole group comprises two concave slotted holes in central symmetry, customized design is carried out according to industrial application occasions and requirements, the leaky coaxial cable has strong radiation performance, and the leaky coaxial cable is suitable for industrial wireless coverage. Wireless signals radiated outwards are uniformly covered, the directivity is strong, and the field intensity is stable; according to the technical scheme of the utility model, the distributed coverage of any area can be flexibly and conveniently realized through interlaced deployment when the wireless communication system is laid to a specific place of an industrial area, no signal blind area or weak area exists, and some new and urgent use requirements in the novel industrial wireless communication field can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a leaky coaxial cable for industrial wireless coverage. Background Art

[0002] In recent years, with the continuous popularization of 5G wireless communication applications, the overall informatization level of China's manufacturing industry will be greatly improved, and significant progress will be made in the digitization, networking, and intelligentization of the manufacturing industry. In the process of building a digital China, a smart society, and developing new industrialization, some new and urgent application requirements have emerged in the field of industrial wireless communication. On the one hand, it is required that the antenna for ultra-high-frequency wireless communication can cover and only cover a specified area, such as only covering the assembly line area in a factory; on the other hand, it is required that the wireless communication antenna can cover some special areas, such as narrow, enclosed, or semi-enclosed spaces, etc., in order to achieve information collection and monitoring of industrial items in all places. Under these different application environment conditions, if a traditional directional radiation antenna is used, it will be difficult to handle due to the overly large beam coverage area or the inability to flexibly adjust. The existing solutions generally use multiple antennas working simultaneously to cover the required area, but this method will greatly increase the cost of industrial wireless coverage and will cause a certain degree of signal waste to some extent. How to find a solution with flexible deployment, convenient adjustment, and low cost to achieve wireless network coverage of special customized narrow areas or other irregular areas in the field of industrial wireless applications is worthy of research.

[0003] Currently, in places where 5G public mobile communication antennas are difficult to cover, such as subway tunnels, mountainous areas, mines, etc., leaky coaxial cables play their good roles as antennas and transmission lines, and the transmitted energy leaks within a certain area to achieve the purpose of signal transmission and antenna radiation at the same time. Considering the characteristics of the above industrial wireless communication application requirements, using leaky coaxial cables is expected to provide an excellent solution. By using a specially designed leaky coaxial cable as an industrial wireless coverage antenna and laying it in specific places in the industrial area, through interleaved deployment, flexible and convenient distributed coverage of any area can be achieved, the wireless signal coverage is uniform and stable, there are no signal blind spots and weak areas, so that the application of industrial object wireless networks in intelligent warehousing, industrial production operations, automatic sorting of logistics transportation, etc. is more accurate, intelligent, and efficient.

[0004] In the wireless communication application of existing leaky coaxial cables, their transmission attenuation is small and the energy radiated outward is low. If directly applied to industrial wireless networks, it will cause problems such as weak signal energy obtained by the receiving end, resulting in disconnection, lag, etc., and cannot meet the requirements of normal operation.

[0005] Based on the above background and application requirements, it is necessary to develop a leaky coaxial cable for industrial wireless coverage with high signal radiation performance, without signal blind spots and weak areas, so that the application of industrial wireless networks in intelligent warehousing, industrial production operations, automatic sorting in logistics transportation, etc. is more accurate, intelligent and efficient. Summary of the Invention

[0006] The object of the present invention is to provide a leaky coaxial cable for industrial wireless coverage in view of the deficiencies of the above-mentioned prior art. It is customized according to industrial application scenarios and requirements, has strong radiation performance, and meets the requirements of new industrial wireless communication.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A leaky coaxial cable for industrial wireless coverage includes an inner conductor, an insulator, an outer conductor and an outer sheath arranged in sequence from inside to outside. The outer conductor is provided with a set of slot holes arranged periodically. Each set of slot holes includes two concave-shaped slot holes that are centrosymmetric, and the centers of the slot holes are located on the same straight line;

[0009] Denote the period of the slot hole group arrayed along the cable axis as P, and P satisfies the following relational expression:

[0010]

[0011] In the formula, λ is the transmission wavelength corresponding to the minimum operating frequency f, and is calculated by the formula λ = c / f,

[0012] c is the propagation speed of electromagnetic waves in free space,

[0013] ε r is the equivalent relative permittivity of the physical foamed insulator of the cable;

[0014] The slot length L of any concave-shaped slot hole satisfies:

[0015] L = 2 n ·P·f0 / c;

[0016] The widths of the two convex parts on both sides of any concave-shaped slot hole are set to be the same, and are denoted as a, and a satisfies:

[0017]

[0018] The length of the concave part of any concave-shaped slot hole is denoted as e, and e satisfies:

[0019]

[0020] In the formula, L is the slot hole length, in mm,

[0021] P is the period length of the slot hole array, in mm,

[0022] f0 is the center frequency of cable transmission, in kHz.

[0023] c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s.

[0024] n is a non-zero natural number.

[0025] For any concave-shaped slot hole in the slot hole group, the heights h of the protruding parts on both sides of the concave-shaped slot hole are the same, and the value range is 3 to 10 mm.

[0026] For any concave-shaped slot hole in the slot hole group, the width of the concave part is denoted as b, and the value range of b is 1 to 4 mm.

[0027] The distance between the centers of two slot holes in the slot hole group is P1, and the distance between the center of the second concave-shaped slot hole and the center of the first concave-shaped slot hole in the next adjacent slot hole group is P2. The two are set the same and are half of the period P.

[0028] The inner conductor is a solid round copper wire, or a copper-clad aluminum wire, or a helically corrugated copper tube welded by copper strips.

[0029] When using a helically corrugated copper tube welded by copper strips, the equivalent outer diameter d satisfies:

[0030] d = (8 - 9)·d 峰 / 10 + (2 - 1)·d 谷 / 10 - t

[0031] Among them, d 峰 is the outer diameter of the wave crest of the inner conductor of the helically corrugated copper tube.

[0032] d 谷 is the outer diameter of the wave trough of the inner conductor of the helically corrugated copper tube.

[0033] t is the thickness of the inner conductor copper strip.

[0034] The equivalent diameters of the inner conductor and the outer conductor satisfy the following relationship:

[0035]

[0036] In the formula, D is the equivalent outer diameter of the outer conductor, d is the equivalent outer diameter of the inner conductor, and ε r is the equivalent relative dielectric constant of the cable foamed insulator.

[0037] The outer conductor is longitudinally wrapped with a smooth or corrugated copper strip with slots.

[0038] The insulator is made by mixing high-density polyethylene, low-density polyethylene, and nucleating agent and foaming with carbon dioxide / nitrogen.

[0039] The outer sheath is made of low-smoke, halogen-free, flame-retardant polyolefin or polyethylene sheath material.

[0040] The beneficial effects of the present invention are as follows:

[0041] (1) The present invention discloses a leaky coaxial cable for industrial wireless coverage. By opening a group of slot holes arranged periodically on the outer conductor, and each group of slot holes includes two concave-shaped slot holes that are centrosymmetric, it is customized according to industrial application scenarios and requirements, has strong radiation performance, and the wireless signals radiated outward are evenly covered, have strong directivity, and stable field strength; when laid in specific industrial areas and through interleaved deployment, it can flexibly and conveniently achieve distributed coverage of any area, without signal blind spots and weak areas, and can meet some new and urgent usage requirements emerging in the field of new industrial wireless communication.

[0042] (2) For the coaxial cable disclosed by the present invention, the wireless signals radiated outward are evenly covered, have strong directivity, and stable field strength. Through interleaved deployment, it can flexibly and conveniently achieve distributed coverage of any area in industrial sites, without signal blind spots and weak areas, thereby making the application of industrial object wireless networks in aspects such as intelligent warehousing, industrial production operations, and automatic sorting of logistics transportation more accurate, intelligent, and efficient.

[0043] (3) When using this leaky coaxial cable for industrial wireless coverage for signal coverage, the cost is saved by more than 25% compared to discrete antenna coverage, and this method is faster in installation and laying, and easier to maintain in the later stage. Description of the Drawings

[0044] Figure 1 is a cross-sectional schematic diagram of the present invention;

[0045] Figure 2 is a schematic diagram of the layer-by-layer structure of the present invention;

[0046] Figure 3 is a schematic diagram of the outer conductor slot hole group structure of the present invention;

[0047] Figure 4 is a coupling loss test diagram of the leaky cable in Embodiment 1 of the present invention;

[0048] Figure 5 is a coupling loss test diagram of the leaky cable in Embodiment 2 of the present invention. Detailed Embodiments

[0049] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0050] The present invention provides a leaky coaxial cable for industrial wireless coverage, as Figures 1 to 5 shown.

[0051] A leaky coaxial cable for industrial wireless coverage includes an inner conductor, an insulator, an outer conductor, and an outer sheath arranged in sequence from inside to outside. The outer conductor is provided with a group of slot holes arranged periodically, which can radiate electromagnetic signals outward or receive electromagnetic signals emitted from the outside; each group of slot holes includes two concave-shaped slot holes that are centrosymmetric, and the centers of the slot holes are located on the same straight line;

[0052] Denote the period of the array of the group of slot holes along the axial direction of the cable as P, and P satisfies the following relationship:

[0053]

[0054] In the formula, λ is the transmission wavelength corresponding to the minimum operating frequency f, calculated by the formula λ = c / f, c is the propagation speed of electromagnetic waves in free space, and ε r is the equivalent relative dielectric constant of the physical foamed insulator of the cable; according to the above relationship, the array period range of the group of slot holes can be determined.

[0055] For any slot hole in the group of slot holes, the slot length L of the concave-shaped slot hole is related to the transmission center frequency of the cable and the array period of the slot holes, and satisfies the following relationship:

[0056] L = 2 n ·P·f0 / c

[0057] In the formula, L is the slot length, in mm; P is the period length of the slot array, in mm; f0 is the center frequency of the cable transmission, in kHz; c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, and n is a natural number, which can take 1, 2, 3, ……

[0058] For any slot hole in the group of slot holes, the widths of the raised parts on both sides of the concave-shaped slot hole are the same, and it satisfies the following relationship with the transmission center frequency of the cable and the array period P of the slot holes:

[0059]

[0060] In the formula, a is the width of the raised part of the concave-shaped slot hole, in mm; P is the period length of the slot array, in mm; f0 is the center frequency of the cable transmission, in kHz; c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, and n is a natural number, which can take 1, 2, 3, ……

[0061] For any slot hole in the group of slot holes, the heights h of the raised parts on both sides of the concave-shaped slot hole are set to be the same, and the value range is 3 to 10 mm.

[0062] For any slot in the slot group, the length e of the concave part of the concave-shaped slot, the transmission center frequency of the cable, and the period of the slot array satisfy the following relationship:

[0063]

[0064] In the formula, e is the length of the concave part of the concave-shaped slot, in mm; P is the period length of the slot array, in mm; f0 is the center frequency of cable transmission, in kHz; c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, n is a natural number and can take 1, 2, 3, …

[0065] For any slot in the slot group, the value range of the height b of the concave part of the concave-shaped slot is 1 to 4 mm.

[0066] In the slot group within one array period, the distance between the centers of two slots is P1, which is set to be equal to the distance P2 between the center of the second slot in one period and the center of the first slot in the next period, and is 1 / 2 times the array period P.

[0067] The inner conductor of the leaky coaxial cable for industrial wireless coverage can be a solid round copper wire, or a copper-clad aluminum wire, or a spiral corrugated copper tube welded with copper tape. When using a spiral corrugated copper tube welded with copper tape, its equivalent outer diameter d of the inner conductor satisfies:

[0068] d = (8 - 9)·d 峰 / 10 + (2 - 1)·d 谷 / 10 - t

[0069] Among them, d 峰 is the outer diameter of the wave crest of the inner conductor of the spiral corrugated copper tube, d 谷 is the outer diameter of the wave trough of the inner conductor of the spiral corrugated copper tube, and t is the thickness of the inner conductor copper tape.

[0070] The outer conductor of the leaky coaxial cable for industrial wireless coverage can be longitudinally wrapped with a smooth or knurled copper tape with slotted holes.

[0071] The equivalent diameters of the inner and outer conductors of the leaky coaxial cable for industrial wireless coverage satisfy the following relationship:

[0072]

[0073] In the formula, D is the equivalent outer diameter of the outer conductor, d is the equivalent outer diameter of the inner conductor, and ε r is the equivalent relative dielectric constant of the cable foamed insulator.

[0074] The insulator of the leaky coaxial cable for industrial wireless coverage is made by mixing high-density polyethylene, low-density polyethylene, and a nucleating agent in a certain proportion and then foaming with carbon dioxide / nitrogen; the outer sheath of the leaky coaxial cable for industrial wireless coverage can be made of low-smoke, halogen-free, flame-retardant polyolefin or polyethylene sheath material according to the requirements of the use environment.

[0075] Furthermore, the polarization mode of the leaky coaxial cable for industrial wireless coverage is vertical polarization.

[0076] In order to make the invention purpose, technical solution and advantages of the present invention clearer, the following combines the drawings and embodiments to detail this patent:

[0077] Embodiment 1:

[0078] As Figure 1 and Figure 2 shown, the structure of the leaky coaxial cable for industrial wireless coverage in this embodiment is, from the inside to the outside in sequence, an inner conductor 1, an insulator 2, an outer conductor 3, and an outer protective layer 4.

[0079] The inner conductor 1 uses copper-clad aluminum wire, and the nominal diameter d of the inner conductor is 4.80 mm; the insulator 2 is composed of physically foamed polyethylene with a skin-foam-skin structure, and the nominal outer diameter of the insulation is 12.5 mm; the outer conductor 3 uses copper tape with a corrugated longitudinal wrap on the insulator 2, the equivalent outer diameter of the outer conductor is 13.0 mm, and the outer protective layer 4 is composed of halogen-free, low-smoke, flame-retardant polyolefin or polyethylene, and the nominal outer diameter of the sheath is 15.5 mm.

[0080] Periodic slot groups 5 for radiating electromagnetic signals outward or receiving externally transmitted electromagnetic signals are opened on the outer conductor 3.

[0081] The period of the periodic slot groups in the axial array along the cable is P, and P satisfies the following relationship:

[0082]

[0083] In the formula, λ is the transmission wavelength corresponding to the minimum operating frequency f, calculated by the formula λ = c / f. In this embodiment, f is taken as 5.6 GHz, c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, and ε r is the equivalent relative dielectric constant of the physically foamed insulator of the cable. In this embodiment, the equivalent dielectric constant is between 1.29 and 1.31. According to the above relationship, the array period P of the slot groups can be determined to be P > 25 mm.

[0084] The periodic array slot groups in this embodiment are composed of two concave-shaped slots that are centrosymmetric within one period, and the centers of the slots are on a straight line.

[0085] For any slot in the slot hole group of this embodiment, the slot length of its concave-shaped slot hole is related to the transmission center frequency of the cable and the period of the slot hole array, and satisfies the following relationship:

[0086] L = 2 n ·P·f0 / c

[0087] In the formula, P is the period length of the slot hole array. In this embodiment, P takes a value of 80 - 90 mm; f0 is the transmission center frequency of the cable. In this embodiment, f0 takes a value of 5.8 GHz; c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, n is a natural number. In this embodiment, n takes a value of 4; L is the slot hole length. After calculation, the slot hole length is 24 - 28 mm;.

[0088] For any slot in the slot hole group of this embodiment, the widths a of the protruding parts on both sides of its concave-shaped slot hole are the same, and it satisfies the following relationship with the transmission center frequency of the cable and the period of the slot hole array:

[0089]

[0090] After calculation, the widths of the protruding parts on both sides of the concave-shaped slot hole in this embodiment are 3.8 - 5.5 mm.

[0091] For any slot in the slot hole group of this embodiment, the heights h of the protruding parts on both sides of its concave-shaped slot hole are the same, and the value range is 3 - 6 mm.

[0092] For any slot in the slot hole group of this embodiment, the length e of the concave part of its concave-shaped slot hole satisfies the following relationship with the transmission center frequency of the cable and the period of the slot hole array:

[0093]

[0094] After calculation, the length of the concave part of the concave-shaped slot hole in this embodiment is 15.4 - 17.8 mm.

[0095] For any slot in the slot hole group of this embodiment, the value range of the height b of the concave part of its concave-shaped slot hole is 1 - 2.5 mm.

[0096] In the slot hole group within one array period of this embodiment, the distance P1 between the centers of two slots is equal to the distance P2 between the center of the second slot within one period and the center of the first slot in the next period, and is 40 - 45 mm.

[0097] For the leakage coaxial cable for industrial wireless coverage in this embodiment, the inner conductor diameter d and the outer conductor equivalent diameter D satisfy the following relationship:

[0098]

[0099] In the formula, ε ris the equivalent relative permittivity of the cable foamed insulator.

[0100] The insulator of the leaky coaxial cable for industrial wireless coverage in this embodiment is made by mixing high-density polyethylene, low-density polyethylene, and a nucleating agent in a certain proportion and then foaming with nitrogen, while the outer sheath is made of low-smoke, halogen-free, flame-retardant polyolefin; the polarization mode of the leaky coaxial cable for industrial wireless coverage is vertical polarization.

[0101] To further verify the implementation effect of the present invention, a sample of the leaky coaxial cable for industrial wireless coverage in Example 1 was tested and analyzed, and its field strength test is as Figure 4 shown. The length of the test sample is 50 meters, the field strength distribution is uniform, the signal fluctuation is small, the directivity is strong, and the 95% coupling loss value measured at 2 meters is 67 dB, which fully meets the requirements of industrial wireless coverage.

[0102] Example 2:

[0103] As Figure 1 and Figure 2 shown, the structure of the leaky coaxial cable for industrial wireless coverage in this embodiment consists of an inner conductor 1, an insulator 2, an outer conductor 3, and an outer sheath 4 from the inside to the outside in sequence.

[0104] The inner conductor 1 is a helically corrugated copper tube or a smooth copper tube welded with a copper strip. The nominal outer diameter of the inner conductor 1 is 7.8 mm. When a helically corrugated copper tube welded with a copper strip is used, the relationship between the peaks and valleys of the corrugated tube of the inner conductor satisfies the following:

[0105] d = (8 - 9)·d 峰 / 10 + (2 - 1)·d 谷 / 10 - t

[0106] where, d 峰 is the outer diameter of the peak of the helically corrugated copper tube inner conductor, d 谷 is the outer diameter of the valley of the helically corrugated copper tube inner conductor, and t is the thickness of the copper strip of the inner conductor.

[0107] The insulator 2 is composed of physically foamed polyethylene with a skin-foam-skin structure, and the nominal outer diameter of the insulation is 19.0 mm; the outer conductor 3 is longitudinally wrapped with a copper strip corrugated on the insulator, the nominal outer diameter of the outer conductor is 19.5 mm, and the outer sheath 4 is composed of halogen-free, low-smoke, flame-retardant polyolefin or polyethylene, and the nominal outer diameter of the sheath is 22.5 mm.

[0108] Periodic slot groups 5 for radiating electromagnetic signals outward or receiving externally transmitted electromagnetic signals are opened on the outer conductor 3.

[0109] The period of the periodic slot groups arrayed in the axial direction of the cable is P, and P satisfies the following relational expression:

[0110]

[0111] In the formula, λ is the transmission wavelength corresponding to the minimum operating frequency f, calculated by the formula λ = c / f. In this embodiment, f is taken as 4.9 GHz, c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, and ε r is the equivalent relative dielectric constant of the physically foamed insulator of the cable. In this embodiment, the equivalent dielectric constant is between 1.25 and 1.28. According to the above relationship, the array period P of the slot group can be determined to be P > 30 mm.

[0112] In the embodiment, the periodic array slot group is composed of two concave-shaped slots that are centrosymmetric within one period, and the centers of the slots are on a straight line.

[0113] For any slot in the slot group of the embodiment, the slot length of the concave-shaped slot is related to the transmission center frequency of the cable and the slot array period, and satisfies the following relationship:

[0114] L = 2 n ·P·f0 / c

[0115] In the formula, P is the period length of the slot array. In this embodiment, P is taken as 110 - 120 mm; f0 is the transmission center frequency of the cable. In this embodiment, f0 is taken as 5.1 GHz; c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, n is a natural number. In this embodiment, n is taken as 4; L is the slot length, and after calculation, the slot length is 30 - 35 mm;

[0116] For any slot in the slot group of the embodiment, the widths of the raised parts on both sides of the concave-shaped slot are the same, and they satisfy the following relationship with the transmission center frequency of the cable and the slot array period:

[0117]

[0118] After calculation, the widths of the raised parts on both sides of the concave-shaped slot in this embodiment are 4 - 6.5 mm.

[0119] For any slot in the slot group of the embodiment, the heights of the raised parts on both sides of the concave-shaped slot are the same, and the value range is 4 - 8 mm.

[0120] For any slot in the slot group of the embodiment, the width of the concave part of the concave-shaped slot satisfies the following relationship with the transmission center frequency of the cable and the slot array period:

[0121]

[0122] After calculation, the width of the concave part of the concave-shaped slot in this embodiment is 20 - 25 mm.

[0123] For any slot hole in the slot hole group of this embodiment, the value range of the height of the concave part of the concave-shaped slot hole is 1.5 to 4 mm.

[0124] In the slot hole group within one array period of this embodiment, the distance P1 between the centers of two slot holes is equal to the distance P2 between the center of the second slot hole in one period and the center of the first slot hole in the next period, and is 55 to 60 mm.

[0125] For the leakage coaxial cable for industrial wireless coverage of this embodiment, the equivalent diameters of the inner and outer conductors satisfy the following relationship:

[0126]

[0127] In the formula, D is the equivalent diameter of the outer conductor, d is the equivalent diameter of the inner conductor, and ε r is the equivalent relative dielectric constant of the cable foamed insulator.

[0128] For the insulator of the leakage coaxial cable for industrial wireless coverage of this embodiment, high-density polyethylene, low-density polyethylene, and a nucleating agent are mixed in a certain proportion and then made by carbon dioxide gas foaming; the outer sheath is made of low-smoke, halogen-free, flame-retardant polyolefin; the polarization mode of the leakage coaxial cable for industrial wireless coverage is vertical polarization.

[0129] In order to further verify the implementation effect of the present invention, the leakage coaxial cable sample for industrial wireless coverage in Embodiment 2 is tested and analyzed, and its field strength test is as Figure 5 shown. The length of the test sample is 50 meters, the signal radiation is strong, the field strength fluctuation is small, and the directivity is good. The coupling loss value of 95% at 2 meters is measured to be 63.7 dB, meeting the requirements of industrial wireless coverage.

[0130] If words such as "first" and "second" are used to limit components in this patent, those skilled in the art should be aware that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and these words have no special meaning.

[0131] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates 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 all fall within the scope of the invention claimed. The scope of the invention claimed is defined by the appended claims and their equivalents.

[0132] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "center", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the protected content of the present invention.

Claims

1. A leaky coaxial cable for industrial wireless coverage, characterized in that: The invention comprises an inner conductor, an insulator, an outer conductor and an outer sheath arranged in sequence from the inside to the outside, and the outer conductor is provided with a periodically arranged slot group, each slot group comprises two concave slots which are centrally symmetrical, and the centers of the slots are located on the same straight line; The period of the slot hole group along the cable axial array is P, and P satisfies the following relationship: Where λ is the transmission wavelength corresponding to the minimum frequency f, and is calculated by the formula λ = c / f, c is the propagation speed of electromagnetic waves in free space, ε r is the equivalent relative dielectric constant of the cable physical foam insulation; The length L of any concave slot hole satisfies: L=2 n ·P·f0 / c; The width of the raised parts on both sides of any concave slot is set to be the same and is recorded as a, and a satisfies: The length of the concave lower part of any concave slot is recorded as e, and e satisfies: Where, L is the slot length, unit: mm, P is the period length of the slot array, in mm, f0 is the center frequency of the cable transmission, in kHz. c is the propagation speed of electromagnetic waves in free space, which is 3×10 8 m / s, n is a non-zero natural number.

2. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: For any concave-shaped slot in the slot group, the height h of the protrusions on both sides of the concave-shaped slot is the same, and the value range is 3 to 10 mm.

3. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: The width of the concave lower part of any concave-shaped slot in the slot group is denoted by b, and the value range of b is 1 to 4 mm.

4. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: The distance between the centers of two slots in the slot group is P1, and the distance between the center of the second concave slot and the center of the first concave slot of the next adjacent slot group is P2, which are identically set and are half of the period P.

5. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: The inner conductor is a solid round copper wire, or a copper-clad aluminum wire, or a spiral corrugated copper tube welded with copper strips.

6. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: When a spiral corrugated copper tube welded with copper strips is used, the equivalent outer diameter d satisfies: d=(8~9)·d 峰 / 10+(2~1)·d 谷 / 10-t Among them, d 峰 is the crest outer diameter of the inner conductor of the spiral corrugated copper tube, d 谷 is the outer diameter of the trough of the inner conductor of the spiral corrugated copper tube, t is the thickness of the inner conductor copper tape.

7. The leaky coaxial cable for industrial wireless coverage according to claim 1, characterized in that: The equivalent diameters of the inner conductor and the outer conductor satisfy the following relationship: Where D is the equivalent diameter of the outer conductor, d is the equivalent outer diameter of the inner conductor, ε r is the equivalent relative dielectric constant of cable foam insulation.

8. A leaky coaxial cable for industrial wireless coverage according to any one of claims 1 to 7, characterized in that: The outer conductor is longitudinally wrapped with a smooth or rolled copper strip with slots.

9. The leaky coaxial cable for industrial wireless coverage according to any one of claims 1 to 7, characterized in that: The insulator is made by mixing high-density polyethylene, low-density polyethylene and a nucleating agent and foaming with carbon dioxide / nitrogen.

10. The leaky coaxial cable for industrial wireless coverage according to any one of claims 1 to 7, characterized in that: The outer sheath is made of low-smoke halogen-free flame-retardant polyolefin or polyethylene sheath material.

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