Spread spectrum leaky cable

Abstract

The application provides a spread spectrum leaky cable, and belongs to the technical field of communication cables.The spread spectrum leaky cable comprises an inner conductor, an insulating layer and an outer conductor arranged in sequence from inside to outside.The number of coincident symmetry axes of the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor is an integer greater than zero and less than or equal to a preset number.The outer conductor is periodically provided with a slot hole along the length direction of the spread spectrum leaky cable.The slot hole is provided at a position corresponding to a preset interval position range of the inner conductor axis center corresponding to the outer conductor position, or a preset interval position range of the outer conductor axis center corresponding to the outer conductor position.By changing the cross-sectional shape of the inner and outer conductors and reducing the number of coincident symmetry axes, the application can make the power supply in the high-order mode only convert in the direction of a small number of symmetry axes, so that the mode field distribution and the transmission path are more stable, and field distribution disorder and signal degradation are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication cables, in particular to a spread spectrum leaky cable. BACKGROUND

[0002] Leaky coaxial cable (LC) is a special communication transmission medium widely used in closed or narrow spaces. Its core structure is usually composed of inner and outer conductors and insulating medium. The cross-sectional shape of the inner and outer conductors is usually designed as a coaxial circle, which ensures the stable transmission of the basic mode (TEM mode) due to the high geometric symmetry between the inner and outer conductors. Through the periodic slotting or spiral gap design of the outer conductor, part of the electromagnetic wave energy is radiated outward during transmission, and external signals can also be received. This "leakage" characteristic makes it an ideal choice for wireless signal coverage in complex environments such as tunnels, subways, mines, and large buildings.

[0003] In the prior art, the leakage strength and direction of the signal are usually controlled by optimizing the physical structure of the LC, such as adjusting the size, shape and spacing of the slot. Or by selecting appropriate medium materials and conductor materials to improve the transmission performance and anti-interference ability of the LC. These design and optimization measures ensure the stability and reliability of the LC to a certain extent within the conventional frequency range.

[0004] However, with the development of communication technology, especially the application of high-frequency communication (such as 5G), the performance of LC at high frequencies has become a key factor restricting its application. When the signal frequency exceeds the cutoff frequency of the LC (a critical value determined by the physical structure of the cable, such as inner diameter, medium material, slot period, etc.), high-order modes (such as TE11, TM01, etc.) will be excited in the cable, and due to the high geometric symmetry of the cross-sectional shape of the inner and outer conductors, the propagation path of the high-order mode can be in any direction, resulting in uneven field distribution. This unevenness destroys the directional radiation characteristics of the LC, making the originally designed uniform electromagnetic field distribution become chaotic, which further causes significant signal degradation.

[0005] Therefore, how to stabilize the high-order modes excited by transmitting signals higher than the cutoff frequency of the LC has become a technical problem to be solved. SUMMARY

[0006] The purpose of the present application is to provide a spread spectrum leaky cable to solve the above problems.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] The spread spectrum leaky cable comprises an inner conductor, an insulating layer and an outer conductor arranged in sequence from inside to outside.

[0009] The number of coincident symmetry axes of the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor is an integer greater than zero and less than or equal to a preset number;

[0010] The outer conductor is periodically provided with a slot hole along the length direction of the spread spectrum leaky cable, and the slot hole is provided at a position corresponding to a preset interval position range of the inner conductor axis center corresponding to the outer conductor position or a preset interval position range of the outer conductor axis center corresponding to the outer conductor position.

[0011] In some embodiments, the first cross-sectional shape and the second cross-sectional shape are respectively divided into four inner conductor quadrants and four outer conductor quadrants by a cross coordinate system, the inner conductor quadrants and the outer conductor quadrants include arc segments, the inner eccentricity of each inner conductor quadrant and the outer eccentricity of each outer conductor quadrant are greater than or equal to a first preset threshold and less than or equal to a second preset threshold, and the smaller the inner eccentricity, the closer the arc segment in the corresponding inner conductor quadrant to a circular arc, and the smaller the outer eccentricity, the closer the arc segment in the corresponding outer conductor quadrant to a circular arc.

[0012] In some embodiments, the inner eccentricity is calculated based on the square root of the absolute value of the square difference between the X-axis length and the Y-axis length of the corresponding inner conductor quadrant, divided by the larger one of the X-axis length and the Y-axis length, and the outer eccentricity is calculated based on the square root of the absolute value of the square difference between the X-axis length and the Y-axis length of the corresponding outer conductor quadrant, divided by the larger one of the X-axis length and the Y-axis length.

[0013] In some embodiments, when the second cross-sectional shape is a circular structure, the first cross-sectional shape satisfies the following conditions:

[0014] The first cross-sectional shape has at least one inner conductor symmetry axis;

[0015] The inner eccentricity of at least two of the first inner conductor quadrant, the second inner conductor quadrant, the third inner conductor quadrant, and the fourth inner conductor quadrant is greater than a preset third threshold, or at least two of the first inner conductor quadrant, the second inner conductor quadrant, the third inner conductor quadrant, and the fourth inner conductor quadrant also contain a straight line segment.

[0016] In some embodiments, when the first cross-sectional shape is a circular structure, the second cross-sectional shape satisfies the following conditions:

[0017] The second cross-sectional shape has at least one outer conductor symmetry axis;

[0018] The eccentricity of at least two of the first, second, third, and fourth outer guides of the four-figures outer guide portion is greater than a third preset threshold, or at least two of the first, second, third, and fourth outer guides further comprise a straight segment.

[0019] In some embodiments, the first cross-sectional shape and the second cross-sectional shape satisfy the following conditions:

[0020] The first cross-sectional shape and the second cross-sectional shape comprise at least one coincident axis of symmetry;

[0021] The eccentricity of at least two of the first, second, third, and fourth inner guides of the four-figures inner guide portion is greater than a third preset threshold, or at least two of the first, second, third, and fourth inner guides further comprise a straight segment.

[0022] The eccentricity of at least two of the first, second, third, and fourth outer guides of the four-figures outer guide portion is greater than a third preset threshold, or at least two of the first, second, third, and fourth outer guides further comprise a straight segment.

[0023] In some embodiments, the concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to a fourth preset threshold and less than or equal to a fifth preset threshold, the greater the concentricity, the higher the center coincidence of the first cross-sectional shape and the second cross-sectional shape, and the concentricity is calculated based on the minimum radial difference and the maximum radial difference of the inner conductor and the outer conductor.

[0024] In some embodiments, when the first cross-sectional shape and the second cross-sectional shape are both circular structures, the first cross-sectional shape and the second cross-sectional shape satisfy the following conditions:

[0025] The concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to a sixth preset threshold and less than a fourth preset threshold, the greater the concentricity, the higher the center coincidence of the first cross-sectional shape and the second cross-sectional shape, and the concentricity is calculated based on the minimum radial difference and the maximum radial difference of the inner conductor and the outer conductor.

[0026] In some embodiments, in the case that the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor have two coincident axes of symmetry with different lengths, when the directions of the inner conductor short axis and the outer conductor short axis are the same, the impedance between the inner conductor and the outer conductor in the short axis direction satisfies the following conditions:

[0027]

[0028] The impedance between the inner conductor and the outer conductor in the long axis direction satisfies the following condition:

[0029]

[0030] wherein Z s is the system impedance, is the impedance between the inner conductor and the outer conductor in the long axis direction, is the impedance between the inner conductor and the outer conductor in the short axis direction, AA i is the length of the arc segment in the long axis direction in each outer conductor section, aa i is the length of the arc segment in the long axis direction in each inner conductor section, BB i is the length of the arc segment in the short axis direction in each outer conductor section, bb i is the length of the arc segment in the short axis direction in each inner conductor section, ε r is the relative dielectric constant.

[0031] In some embodiments, in the case where the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor have two coinciding axes of symmetry of different lengths, when the directions of the inner conductor short axis and the outer conductor short axis are orthogonal, the impedance between the inner conductor and the outer conductor in the short axis direction satisfies the following condition:

[0032]

[0033] The impedance between the inner conductor and the outer conductor in the long axis direction satisfies the following condition:

[0034]

[0035] wherein Z s is the system impedance, is the impedance between the inner conductor and the outer conductor in the long axis direction, is the impedance between the inner conductor and the outer conductor in the short axis direction, AA i is the length of the arc segment in the long axis direction in each outer conductor section, aa i is the length of the arc segment in the long axis direction in each inner conductor section, BB i is the length of the arc segment in the short axis direction in each outer conductor section, bb i is the length of the arc segment in the short axis direction in each inner conductor section, ε r is the relative dielectric constant.

[0036] Compared with the prior art, the application has the following beneficial effects:

[0037] The present application controls the number of coincident symmetry axes of the cross-sectional shapes of the inner and outer conductors to be no more than a preset number by setting different cross-sectional shapes, so that the high-order mode propagation path is limited and can only propagate along a small number of coincident symmetry axes, making the mode field distribution and transmission path more stable, avoiding field distribution confusion and signal degradation. In addition, since the high-order mode propagation path is stabilized, the feed is concentrated in a few directions, thus improving the signal leakage efficiency, optimizing the wireless signal coverage effect, and enhancing the high-frequency application performance of the leaky cable. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope of the present application.

[0039] Figure 1 A cross-sectional structure schematic diagram of a coaxial cable in the prior art;

[0040] Figure 2 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0041] Figure 3 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0042] Figure 4 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0043] Figure 5 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0044] Figure 6 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0045] Figure 7 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0046] Figure 8 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0047] Figure 9 A cross-sectional structure schematic diagram of a spread spectrum leaky cable provided by the present application;

[0048] Figure 10 A signal attenuation curve schematic diagram of a leaky cable provided by the prior art in an overcut-off frequency transmission scenario;

[0049] Figure 11The signal attenuation curve of the spread spectrum leaky cable provided by the present application in the super cut-off frequency transmission scenario is shown in the figure.

[0050] The figure number is explained: 10, inner conductor; 20, outer conductor; 30, slot hole. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0052] All the terms used in the present application (including technical and scientific terms) have the meanings generally understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted to have meanings consistent with the context of the present specification, and should not be interpreted in an idealized or overly formal manner.

[0053] For example, the terms "first", "second", etc. used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first cross-sectional shape can be referred to as the second cross-sectional shape, and similarly, the second cross-sectional shape can be referred to as the first cross-sectional shape. Both the first cross-sectional shape and the second cross-sectional shape are cross-sectional shapes, but they are not the same cross-sectional shape.

[0054] For another example, the terms "including", "containing", etc. used in the present application indicate the presence of a feature, step, operation and / or component, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0055] As mentioned earlier, leaky coaxial cable (referred to as leaky cable) is a special communication transmission medium widely used in closed or narrow space. Its core structure is usually composed of inner and outer conductors and insulating medium, and the cross-sectional shape of the inner and outer conductors is usually as Figure 1The coaxial circular design shown has high geometric symmetry between the inner and outer conductors, ensuring stable transmission of the base mode (TEM mode). Through the periodic slotting or spiral slot design of the outer conductor, part of the electromagnetic wave energy is radiated outward during transmission, and external signals can also be received. This "leakage" characteristic makes it an ideal choice for wireless signal coverage in complex environments such as tunnels, subways, mines, and large buildings. However, with the development of communication technology, especially the application of high-frequency communication (such as 5G), the performance of leaky cables at high frequencies has become a key factor restricting their application. When the signal frequency exceeds the cutoff frequency of the leaky cable (a critical value determined by the physical structure of the cable, such as inner diameter, dielectric material, slot period, etc.), high-order modes (such as TE 11 , TM 01 , etc.) will be excited in the cable, and due to the high geometric symmetry of the cross-sectional shape of the inner and outer conductors, the propagation path of the high-order modes can be in any direction, leading to unevenness of the field distribution. This unevenness destroys the directional radiation characteristics of the leaky cable, making the originally designed uniform electromagnetic field distribution become chaotic, which in turn causes significant signal degradation. Therefore, how to stabilize the high-order modes excited by signals transmitted above the cutoff frequency of the leaky cable has become a technical problem that needs to be solved. To this end, the present application proposes a spread spectrum leaky cable, the cross-sectional shape of the inner conductor and the outer conductor has a certain number of coincident symmetry axes (greater than zero and less than or equal to a preset number), and the outer conductor slot opening position corresponds to the inner conductor or outer conductor axis center corresponding to the preset interval position range of the outer conductor position.

[0056] As shown in Figures 2 to 9 , the spread spectrum leaky cable of the present embodiment includes an inner conductor 10, an insulating layer (not shown in the figure), and an outer conductor 20 arranged in order from inside to outside; the number of coincident symmetry axes of the first cross-sectional shape of the inner conductor 10 and the second cross-sectional shape of the outer conductor 20 is an integer greater than zero and less than or equal to a preset number; the outer conductor 20 is periodically provided with a slot 30 along the length direction of the spread spectrum leaky cable, and the slot opening position corresponds to the preset interval position range of the inner conductor axis center corresponding to the outer conductor position, or the preset interval position range of the outer conductor axis center corresponding to the outer conductor position.

[0057] The inner conductor 10 in the present embodiment is the core part of the spread spectrum leaky cable, usually made of high-conductivity materials (such as copper, aluminum, etc.), used for transmitting electrical signals. The insulating layer is located between the inner conductor 10 and the outer conductor 20, made of insulating materials (polyethylene, polyvinyl chloride), used for electrical isolation and support of the inner conductor 10. The outer conductor 20 is the shielding layer of the spread spectrum leaky cable, usually made of braided metal wires or metal foils, used for shielding electromagnetic interference.

[0058] In this embodiment, the first cross-sectional shape refers to the cross-sectional shape of the inner conductor 10 in the direction perpendicular to the length of the spread spectrum leaky cable. It can be circular, elliptical, or other non-circular structure with at least one inner conductor axis of symmetry. The second cross-sectional shape refers to the cross-sectional shape of the outer conductor 20 in the direction perpendicular to the length of the spread spectrum leaky cable. It can be circular, elliptical, or other non-circular structure with at least one outer conductor axis of symmetry. Coincident axes of symmetry refer to those axes that simultaneously serve as the axes of symmetry for both the first cross-sectional shape of the inner conductor 10 and the second cross-sectional shape of the outer conductor 20. For example... Figure 2 The spread spectrum leaky cable shown has a circular second cross-section and a non-circular first cross-section with only one inner conductor axis of symmetry, meaning it has only one coincident axis of symmetry perpendicular to the cable's length. The preset quantity refers to the number of coincident axes of symmetry for the inner and outer conductors 20, pre-set according to specific application requirements and performance targets during the design of the spread spectrum leaky cable. This quantity is a value greater than zero and less than or equal to a certain integer (such as 1, 2, etc.), used to control the cable's electromagnetic characteristics, particularly the propagation behavior of higher-order modes and signal leakage modes. By setting the cross-sectional shapes of the inner conductor 10 and outer conductor 20 respectively, the number of coincident axes of symmetry can be adjusted, thereby controlling the propagation path of higher-order modes, reducing unwanted radiation, and improving the stability and directionality of signal transmission.

[0059] In this embodiment, the slot 30 is a periodically opened opening (which can be straight, spiral, or other shapes) on the outer conductor 20, used to control electromagnetic wave leakage. The opening position of the slot 30 corresponds to a preset range of positions between the center of the inner conductor axis and the position of the outer conductor, or a preset range of positions between the center of the outer conductor axis and the position of the outer conductor.

[0060] Specifically, the slot 30 can be formed within ±30mm of the position of the outer conductor 20 corresponding to the center of its major axis or the position of the outer conductor 20 corresponding to the center of its minor axis; the slot 30 can also be formed within ±30mm of the position of the outer conductor 10 corresponding to the center of its major axis or the position of the outer conductor 10 corresponding to the center of its minor axis. Preferably, the slot 30 is formed at the position where the distance between the inner and outer conductors is minimal (the minimum radial difference between the inner conductor 10 and the outer conductor 20). By placing the slot 30 near the axis center and arranging it periodically along the length of the spread spectrum leaky cable, the strongest electric field can be excited, improving signal transmission efficiency.

[0061] In some embodiments, the first cross-sectional shape and the second cross-sectional shape are each divided into four inner quadrants and four outer quadrants by a cross coordinate system, each quadrant including one inner quadrant or outer quadrant, and the inner quadrants and the outer quadrants refer to the divided parts of the cross sections of the inner conductor 10 and the outer conductor 20 in the four quadrants. The inner quadrants and the outer quadrants include arc segments, and the inner eccentricity of each inner quadrant in the four inner quadrants and the outer eccentricity of each outer quadrant in the four outer quadrants are greater than or equal to a first preset threshold (such as 0) and less than or equal to a second preset threshold (such as 0.92), wherein the inner eccentricity or the outer eccentricity is a parameter for describing the degree of deviation of the first cross-sectional shape or the second cross-sectional shape from a circular shape, and the smaller the inner eccentricity, the closer the arc segment in the corresponding inner quadrant to a circular arc, and the smaller the outer eccentricity, the closer the arc segment in the corresponding outer quadrant to a circular arc. By setting the first preset threshold and the second preset threshold, it is possible to avoid the cross-sectional shape being too flat, thereby ensuring the mechanical strength and electromagnetic performance of the spread spectrum leakage cable.

[0062] Specifically, the inner eccentricity is calculated based on the absolute value of the square difference of the X-axis length and the Y-axis length of the corresponding inner quadrant, divided by the larger one of the X-axis length and the Y-axis length.

[0063] Exemplarily, as shown in Figure 3 , the eccentricity e i (i = 1, 2, 3, 4) is calculated according to formula (1):

[0064]

[0065] wherein a i ≥ b i .

[0066] The first inner guide section corresponding to the left lower part, a1 = aa1 + Δa1, b1 = bb2 + Δb1; the second inner guide section corresponding to the right lower part, a2 = aa2 + Δa2, b2 = bb3 + Δb2; the third inner guide section corresponding to the left upper part, a3 = aa3 + Δa3, b3 = bb1 + Δb3; the fourth inner guide section corresponding to the right upper part, a4 = aa4 + Δa4, b4 = bb4 + Δb4. Wherein, a1 is the X-axis length of the complete figure corresponding to the arc segment in the first inner guide section, b1 is the Y-axis length of the first inner guide section, a2 is the X-axis length of the complete figure corresponding to the arc segment in the second inner guide section, b2 is the Y-axis length of the complete figure corresponding to the arc segment in the second inner guide section, a3 is the X-axis length of the complete figure corresponding to the arc segment in the third inner guide section, b3 is the Y-axis length of the complete figure corresponding to the arc segment in the third inner guide section, a4 is the X-axis length of the complete figure corresponding to the arc segment in the fourth inner guide section, b1 is the Y-axis length of the complete figure corresponding to the arc segment in the fourth inner guide section. aa1 is the X-axis length of the actually existing arc segment in the first inner guide section, bb2 is the Y-axis length of the actually existing arc segment in the first inner guide section, aa2 is the X-axis length of the actually existing arc segment in the second inner guide section, bb3 is the Y-axis length of the actually existing arc segment in the second inner guide section, aa3 is the X-axis length of the actually existing arc segment in the third inner guide section, bb4 is the Y-axis length of the actually existing arc segment in the third inner guide section, aa4 is the X-axis length of the actually existing arc segment in the fourth inner guide section, bb1 is the Y-axis length of the actually existing arc segment in the fourth inner guide section. Δa1, Δa2, Δa3, Δa4, Δb1, Δb3, Δb2 and Δb4 refer to the error between the axis length of the complete figure corresponding to the arc segment in each inner guide section and the axis length of the actually existing arc segment.

[0067] Similarly, the outer guide eccentricity is calculated based on the square difference of the X-axis length and the Y-axis length of the corresponding outer guide section, and then divided by the larger value of the X-axis length and the Y-axis length. Exemplarily, the eccentricity Ei (i = 1, 2, 3, 4) of each outer guide section is shown in formula (2):

[0068]

[0069] Wherein, A i ≥B i .

[0070] Corresponding to the first outer guide part of the lower left part, A1=AA1+ΔA1, B1=BB2+ΔB1; corresponding to the second outer guide part of the lower right part, A2=AA2+ΔA2, B2=BB3+ΔB2; corresponding to the third outer guide part of the upper left part, A3=AA3+ΔA3, B3=BB1+ΔB3; corresponding to the fourth outer guide part of the upper right part, A4=AA4+ΔA4, B4=BB4+ΔB4. Wherein, A1 is the X-axis length of the complete figure corresponding to the arc segment in the first outer guide part, B1 is the Y-axis length of the complete figure corresponding to the arc segment in the first outer guide part, A2 is the X-axis length of the complete figure corresponding to the arc segment in the second outer guide part, B2 is the Y-axis length of the complete figure corresponding to the arc segment in the second outer guide part, A3 is the X-axis length of the complete figure corresponding to the arc segment in the third outer guide part, B3 is the Y-axis length of the complete figure corresponding to the arc segment in the third outer guide part, A4 is the X-axis length of the complete figure corresponding to the arc segment in the fourth outer guide part, B4 is the Y-axis length of the complete figure corresponding to the arc segment in the fourth outer guide part. ΔA1, ΔA2, ΔA3, ΔA4, ΔB1, ΔB3, ΔB2 and ΔB4 refer to the error between the axis length of the complete figure corresponding to the arc segment in each outer guide part and the actual axis length of the arc segment.

[0071] In one embodiment, as shown in Figure 2 and Figure 4 When the second cross-sectional shape is a circular structure, the first cross-sectional shape satisfies the following conditions:

[0072] The first cross-sectional shape has at least one outer guide symmetry axis; the inner guide eccentricity of at least two of the first inner guide part, the second inner guide part, the third inner guide part and the fourth inner guide part in the four inner guide parts is greater than a preset third threshold value (such as 0.1), or at least two of the first inner guide part, the second inner guide part, the third inner guide part and the fourth inner guide part also contain a straight line segment. At this time, the first inner guide eccentricity is equal to the second eccentricity, and the third inner guide eccentricity is equal to the fourth eccentricity; and / or, the first inner guide eccentricity is equal to the third eccentricity, and the second inner guide eccentricity is equal to the fourth eccentricity.

[0073] In another embodiment, as shown in Figure 5 and Figure 6 When the first cross-sectional shape is a circular structure, the second cross-sectional shape satisfies the following conditions:

[0074] The second cross-sectional shape has at least one outer guide symmetry axis ；The eccentricity of at least two of the first, second, third and fourth outer guides is greater than a third preset threshold (e.g., 0.1), or at least two of the first, second, third and fourth outer guides further comprise a straight line segment. In this case, the first outer guide eccentricity is equal to the second eccentricity, and the third outer guide eccentricity is equal to the fourth eccentricity; and / or, the first outer guide eccentricity is equal to the third eccentricity, and the second outer guide eccentricity is equal to the fourth eccentricity.

[0075] In another embodiment, as shown in Figure 7 and Figure 8 The first cross-sectional shape and the second cross-sectional shape satisfy the following conditions:

[0076] The first cross-sectional shape and the second cross-sectional shape comprise at least one coincident symmetry axis; the eccentricity of at least two of the first, second, third and fourth inner guides is greater than a third preset threshold (e.g., 0.1), or at least two of the first, second, third and fourth inner guides further comprise a straight line segment; the eccentricity of at least two of the first, second, third and fourth outer guides is greater than a third preset threshold, or at least two of the first, second, third and fourth outer guides further comprise a straight line segment.

[0077] It should be noted that, Figures 2 to 8 The cross-sectional shape of the inner and outer guides and the number of coincident symmetry axes are only one example in the corresponding case, and do not limit the embodiments of the application.

[0078] Based on the above embodiments of the first cross-sectional shape and the second cross-sectional shape, in some embodiments, the concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to a fourth preset threshold (e.g., 0.94) and less than or equal to a fifth preset threshold (e.g., 1), the greater the concentricity, the higher the center coincidence of the first cross-sectional shape and the second cross-sectional shape, and the concentricity is calculated based on the minimum radial difference and the maximum radial difference of the inner conductor 10 and the outer conductor 20. Specifically, as shown in formula (3):

[0079]

[0080] Where C is the concentricity, h max is the maximum radial difference, h min is the minimum radial difference. By accurately controlling the concentricity of the inner and outer conductors 20, the mechanical strength and electromagnetic performance of the cable are ensured, and the stability and reliability of signal transmission are improved.

[0081] In another embodiment, such as Figure 9 As shown in the figure, the two solid black dots represent the centers of the first and second cross-sectional shapes, respectively. When both the first and second cross-sectional shapes are circular structures, they satisfy the following condition:

[0082] The concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to the sixth preset threshold (e.g., 0) and less than the fourth preset threshold (e.g., 0.94). The greater the concentricity, the higher the center overlap of the first cross-sectional shape and the second cross-sectional shape. The concentricity is calculated based on the minimum radial difference and the maximum radial difference between the inner conductor 10 and the outer conductor 20. The calculation formula is referred to formula (3), which will not be elaborated here in this embodiment.

[0083] Furthermore, to ensure signal transmission performance, the impedance between the inner and outer conductors needs to be matched with the system impedance to guarantee system signal transmission. In some implementations, where the inner and outer conductors have two coincident axes of symmetry of different lengths, such as... Figure 3 As shown, when the inner short axis of the inner conductor 10 and the outer short axis of the outer conductor 20 are in the same direction, the impedance between the inner conductor 10 and the outer conductor 20 in the short axis direction satisfies the following formula (4):

[0084]

[0085] The impedance between the inner conductor 10 and the outer conductor 20 along the long axis satisfies the following formula (5):

[0086]

[0087] Among them, Z s For system impedance, The impedance between the inner conductor and the outer conductor along the long axis. AA is the impedance between the inner conductor and the outer conductor in the short axis direction. i Let aa be the length of the arc segment in each outer guide section along its major axis. i BB represents the length of the arc segment in each inner guide section along its major axis. i Let bb be the length of the arc segment in each outer guide section along the minor axis. i ε represents the length of the arc segment in each inner guide section along its minor axis. r is the relative permittivity.

[0088] In some embodiments, in the case where the inner and outer conductors have two different-length coincident axes of symmetry, when the directions of the inner conductor short axis of the inner conductor 10 and the outer conductor short axis of the outer conductor 20 are orthogonal, the impedance between the inner conductor 10 and the outer conductor 20 in the short axis direction satisfies the following formula (6):

[0089]

[0090] The impedance between the inner conductor 10 and the outer conductor 20 in the long axis direction satisfies the following formula (7):

[0091]

[0092] wherein Z s is the system impedance, is the impedance between the inner conductor and the outer conductor in the long axis direction, is the impedance between the inner conductor and the outer conductor in the short axis direction, AA i is the length of the arc segment in the long axis direction in each outer conductor section, aa i is the length of the arc segment in the long axis direction in each inner conductor section, BB i is the length of the arc segment in the short axis direction in each outer conductor section, bb i is the length of the arc segment in the short axis direction in each inner conductor section, ε r is the relative dielectric constant.

[0093] Finally, by comparing the signal attenuation curves in Figure 10 and Figure 11 (the horizontal axis refers to the signal frequency, and the vertical axis refers to the signal strength), it can be seen that in the transmission scenario of the super cutoff frequency, the present application has more stable signal transmission effect compared with the prior art.

[0094] In the spread spectrum leaky cable proposed in the embodiments of the present application, by setting different cross-sectional shapes for the inner and outer conductors, the number of coincident axes of symmetry of the cross-sectional shapes of the inner and outer conductors is controlled to be not more than a preset number, so that the high-order mode propagation path is limited and can only propagate along a small number of coincident axes of symmetry, so that the mode field distribution and the transmission path are more stable, and field distribution confusion and signal degradation are avoided. In addition, since the high-order mode propagation path is stabilized, the feed is concentrated in a small number of directions, so the signal leakage efficiency is improved, the wireless signal coverage effect can be optimized, and the high-frequency application performance of the leaky cable is enhanced.

[0095] Those skilled in the art should understand that, in the disclosure of the present application, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the systems or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation on the present application.

[0096] In the description of the present application, the description of "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0097] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A spread spectrum leaky cable, characterized in that, The spread spectrum leaky cable includes an inner conductor, an insulation layer, and an outer conductor arranged sequentially from the inside out. The number of coincident symmetry axes between the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor is an integer greater than zero and less than or equal to a preset number. The first cross-sectional shape and the second cross-sectional shape are respectively divided into a four-dimensional inner conductor and a four-dimensional outer conductor by a cross coordinate system. The outer conductor is periodically provided with slots along the length of the spread spectrum leaky cable. The slots are located within a preset range of positions corresponding to the position of the outer conductor and the center of the inner conductor axis. When the second cross-section is circular, the shape of the first cross-section satisfies the following condition: The first cross-sectional shape has at least one internal guiding symmetry axis, and the internal guiding eccentricity of at least two of the first, second, third and fourth internal guiding parts in the four internal guiding parts is greater than a preset third threshold, or, at least two of the first, second, third and fourth internal guiding parts also include a straight line segment; When the first cross-section is circular, the shape of the second cross-section satisfies the following condition: The second cross-sectional shape has at least one external guide symmetry axis, and the external guide eccentricity of at least two of the four external guide parts (first, second, third, and fourth) is greater than a preset third threshold, or at least two of the four external guide parts (first, second, third, and fourth) also include a straight line segment.

2. The spread spectrum leaky cable according to claim 1, characterized in that, The inner guide portion and the outer guide portion include arc segments. The inner guide eccentricity of each inner guide portion in the four-dimensional inner guide portion and the outer guide eccentricity of each outer guide portion in the four-dimensional outer guide portion are both greater than or equal to a first preset threshold and less than or equal to a second preset threshold. The smaller the inner guide eccentricity, the closer the arc segment in the corresponding inner guide portion is to a circular arc. The smaller the outer guide eccentricity, the closer the arc segment in the corresponding outer guide portion is to a circular arc.

3. The spread spectrum leaky cable according to claim 2, characterized in that, The inner guide eccentricity is calculated by taking the square root of the absolute value of the square difference between the X-axis length and Y-axis length of the corresponding inner guide part and dividing it by the larger of the X-axis length and Y-axis length. The outer guide eccentricity is calculated by taking the square root of the absolute value of the square difference between the X-axis length and Y-axis length of the corresponding outer guide part and dividing it by the larger of the X-axis length and Y-axis length.

4. The spread spectrum leaky cable according to claim 1, characterized in that, The concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to a fourth preset threshold and less than or equal to a fifth preset threshold. The greater the concentricity, the higher the center overlap of the first cross-sectional shape and the second cross-sectional shape. The concentricity is calculated based on the minimum radial difference and the maximum radial difference between the inner conductor and the outer conductor.

5. The leaky cable according to claim 1, characterized in that, When the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor have two coincident axes of symmetry of different lengths, and when the directions of the inner minor axis of the inner conductor and the outer minor axis of the outer conductor are the same, the impedance between the inner conductor and the outer conductor in the direction of the minor axis satisfies the following condition: The impedance between the inner conductor and the outer conductor along the major axis satisfies the following condition: in, For system impedance, The impedance between the inner conductor and the outer conductor along the long axis. The impedance between the inner conductor and the outer conductor in the short axis direction. Let be the length of the arc segment in each outer guide section along its major axis. Let be the length of the arc segment in each inner guide section along its major axis. Let be the length of the arc segment in each outer guide section along the minor axis. Let be the length of the arc segment in each inner guide section along the minor axis. is the relative permittivity.

6. The leaky cable according to claim 1, characterized in that, When the first cross-sectional shape of the inner conductor and the second cross-sectional shape of the outer conductor have two coincident axes of symmetry of different lengths, and when the directions of the inner minor axis of the inner conductor and the outer minor axis of the outer conductor are orthogonal, the impedance between the inner conductor and the outer conductor in the direction of the minor axis satisfies the following condition: The impedance between the inner conductor and the outer conductor along the major axis satisfies the following condition: in, For system impedance, The impedance between the inner conductor and the outer conductor along the long axis. The impedance between the inner conductor and the outer conductor in the short axis direction. Let be the length of the arc segment in each outer guide section along its major axis. Let be the length of the arc segment in each inner guide section along its major axis. Let be the length of the arc segment in each outer guide section along the minor axis. Let be the length of the arc segment in each inner guide section along the minor axis. is the relative permittivity.

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