Spread spectrum leaky cable

Abstract

The invention provides a spread spectrum leaky cable, and belongs to the technical field of communication cables, and the spread spectrum leaky cable comprises an inner conductor, an insulating layer and an outer conductor which are sequentially arranged from inside to outside. The number of coincident symmetry axes of the first cross-section shape of the inner conductor and the second cross-section shape of the outer conductor is an integer greater than zero and less than or equal to a preset number; slotted holes are periodically formed in the outer conductor in the length direction of the spread spectrum leaky cable, and the forming positions of the slotted holes correspond to the preset interval position range of the position, corresponding to the outer conductor, of the axis center of the inner conductor, or the preset interval position range of the position, corresponding to the outer conductor, of the axis center of the outer conductor. By changing the cross section shapes of the inner conductor and the outer conductor and reducing the number of overlapped symmetry axes, feed in a high-order mode state can be converted only in the direction of a small number of symmetry axes, so that mode field distribution and a 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, and particularly to a spread-spectrum leaky cable. Background Art

[0002] A leaky coaxial cable (referred to as a leaky cable for short) is a special communication transmission medium widely used in enclosed or narrow spaces. Its core structure usually consists of an inner conductor, an insulating layer, and an outer conductor. The cross-sectional shapes of the inner and outer conductors are usually circular designs that are coaxial inside and outside. This design makes the inner and outer conductors have a high degree of geometric symmetry, thus ensuring the stable transmission of the fundamental mode (TEM mode). Through the periodic slotted or helical slot design of the outer conductor, part of the electromagnetic wave energy radiates 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, usually by optimizing the physical structure of the leaky cable, such as adjusting the size, shape, and spacing of the slots, to control the leakage intensity and direction of the signal. Or by selecting appropriate dielectric materials and conductor materials to improve the transmission performance and anti-interference ability of the leaky cable. These design and optimization measures ensure the stability and reliability of the leaky cable within a certain conventional frequency range to a certain extent.

[0004] However, with the development of communication technology, especially the application of high-frequency communication (such as 5G), the performance of the leaky cable in the high-frequency band has become a key factor restricting its application. When the signal frequency exceeds the cut-off frequency of the leaky cable (a critical value determined by the physical structure of the cable, such as the inner diameter, dielectric material, slotting period, etc.), higher-order modes (such as TE11, TM01, etc. high-order electromagnetic modes) will be excited in the cable. Due to the high degree of geometric symmetry of the cross-sectional shapes of the inner and outer conductors, the propagation path of the higher-order modes may be in any direction, resulting in non-uniform field distribution. This non-uniformity destroys the directional radiation characteristics of the leaky cable, making the originally designed uniform electromagnetic field distribution chaotic, and thus causing significant signal degradation.

[0005] Therefore, how to stabilize the higher-order modes excited by transmitting signals higher than the cut-off frequency of the leaky cable has become an urgent technical problem to be solved. Summary of the Invention

[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 present application adopts the following technical solutions:

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

[0009] The number of coincidence 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 slot holes along the length direction of the spread spectrum leakage cable, and the opening positions of the slot holes correspond to the preset interval position ranges of the positions corresponding to the inner conductor axis center of the outer conductor or the preset interval position ranges of the positions corresponding to the outer conductor axis center of the outer conductor.

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

[0012] In some embodiments, the inner conductor eccentricity is calculated by taking 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 part and then dividing by the larger value of the X-axis length and the Y-axis length. The outer conductor eccentricity is calculated by taking 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 part and then dividing by the larger value 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 conductor eccentricities of at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part in the four-quadrant inner conductor part are greater than a preset third threshold, or at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part also include straight line segments.

[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 outer guide eccentricity of at least two of the first outer guide part, the second outer guide part, the third outer guide part, and the fourth outer guide part in the four-image outer guide part is greater than a preset third threshold, or at least two of the first outer guide part, the second outer guide part, the third outer guide part, and the fourth outer guide part further include straight line segments.

[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 have at least one coincident axis of symmetry;

[0021] 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-image inner guide part is greater than a preset third threshold, 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 further include straight line segments;

[0022] The outer guide eccentricity of at least two of the first outer guide part, the second outer guide part, the third outer guide part, and the fourth outer guide part in the four-image outer guide part is greater than a preset third threshold, or at least two of the first outer guide part, the second outer guide part, the third outer guide part, and the fourth outer guide part further include straight line segments.

[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 coincidence degree of the centers 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.

[0024] In some embodiments, when both the first cross-sectional shape and the second cross-sectional shape are 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 the fourth preset threshold. The greater the concentricity, the higher the coincidence degree of the centers 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.

[0026] 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 coincident axes of symmetry with different lengths, when the directions of the inner guide minor axis of the inner conductor and the outer guide minor axis of the outer conductor are the same, the impedance between the inner conductor and the outer conductor in the minor 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 conditions:

[0029]

[0030] where 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 in the long axis direction of the arc segment in each outer guide part, aa i is the length in the long axis direction of the arc segment in each inner guide part, BB i is the length in the short axis direction of the arc segment in each outer guide part, bb i is the length in the short axis direction of the arc segment in each inner guide part, ε r is the relative permittivity.

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

[0032]

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

[0034]

[0035] where 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 in the long axis direction of the arc segment in each outer guide part, aa i is the length in the long axis direction of the arc segment in each inner guide part, BB i is the length in the short axis direction of the arc segment in each outer guide part, bb i is the length in the short axis direction of the arc segment in each inner guide part, ε r is the relative permittivity.

[0036] Compared with the prior art, the beneficial effects of the present application include:

[0037] By setting different cross-sectional shapes, the present application controls the number of coincidence symmetry axes of the cross-sectional shapes of the inner and outer conductors not to exceed a preset number, so that the propagation path of the higher-order modes is restricted and can only propagate along a small number of coincidence symmetry axis directions, making the mode field distribution and the transmission path more stable, and avoiding the chaos of the field distribution and the deterioration of the signal. In addition, since the propagation path of the higher-order modes is stabilized and the feeding is concentrated in a few directions, the signal leakage efficiency is improved, the wireless signal coverage effect can be optimized, and the high-frequency application performance of the leaky cable can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use 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 should not be regarded as limiting the scope of the present application.

[0039] Figure 1 FIG. 10 is a schematic cross-sectional structure diagram of a coaxial cable in the prior art;

[0040] Figure 2 FIG. 14 is one of the schematic cross-sectional structure diagrams of the spread-spectrum leaky cable provided by the present application;

[0041] Figure 3 FIG. 18 is another schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0042] Figure 4 FIG. 22 is a third schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0043] Figure 5 FIG. 26 is a fourth schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0044] Figure 6 FIG. 30 is a fifth schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0045] Figure 7 FIG. 34 is a sixth schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0046] Figure 8 FIG. 38 is a seventh schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0047] Figure 9 FIG. 42 is an eighth schematic cross-sectional structure diagram of the spread-spectrum leaky cable provided by the present application;

[0048] Figure 10 FIG. 46 is a schematic diagram of the signal attenuation curve of the leaky cable provided by the prior art in the super cutoff frequency transmission scenario;

[0049] Figure 11Schematic diagram of the signal attenuation curve of the spread spectrum leaky cable provided by this application in the ultra-cutoff frequency transmission scenario.

[0050] Explanation of the reference numerals in the attached drawings: 10, inner conductor; 20, outer conductor; 30, slot. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of this application clearer and more understandable, the following further details this application in combination with the attached drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

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

[0053] For example, terms such as "first" and "second" used in this application may 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 this application, the first cross-sectional shape may be called the second cross-sectional shape, and similarly, the second cross-sectional shape may be called 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, terms such as "including" and "comprising" used in this application indicate the existence of features, steps, operations, and / or components, but do not exclude the existence or addition of one or more other features, steps, operations, or components.

[0055] As mentioned above, leaky coaxial cable (abbreviated as leaky cable) is a special communication transmission medium widely used in enclosed or narrow spaces. Its core structure usually consists of inner and outer conductors and an insulating medium, and the cross-sectional shapes of the inner and outer conductors are usually as Figure 1The shown coaxial circular design inside and outside makes the geometry between the inner and outer conductors highly symmetric, thus ensuring the stable transmission of the fundamental mode (TEM mode). Through the periodic slotted or spiral-shaped slot design of the outer conductor, part of the electromagnetic wave energy radiates 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 in the high-frequency band has become a key factor restricting their application. When the signal frequency exceeds the cut-off frequency of the leaky cable (a critical value determined by the physical structure of the cable, such as the inner diameter, dielectric material, slotting period, etc.), higher-order modes (such as TE 11 and TM 01 and other higher-order electromagnetic modes) will be excited inside the cable. Due to the high geometric symmetry of the cross-sectional shapes of the inner and outer conductors, the propagation path of the higher-order modes can be in any direction, resulting in the non-uniformity of the field distribution. This non-uniformity destroys the directional radiation characteristics of the leaky cable, making the originally designed uniform electromagnetic field distribution chaotic, and further causing a significant deterioration of the signal. Therefore, how to stabilize the higher-order modes excited by transmitting signals above the cut-off frequency of the leaky cable has become an urgent technical problem to be solved. For this reason, the present application proposes a spread-spectrum leaky cable. The cross-sectional shapes of the inner conductor and the outer conductor have a certain number of coincident symmetry axes (greater than zero and less than or equal to a preset number), and the opening positions of the slots in the outer conductor correspond to the preset interval positions within the inner conductor corresponding to the center of the outer conductor or the outer conductor corresponding to the center of the outer conductor. By changing the cross-sectional shapes of the inner and outer conductors and reducing the number of coincident symmetry axes, the feeding in the higher-order mode state is only converted in a small number of symmetry axis directions.

[0056] As Figures 2 to 9 shown, the spread-spectrum leaky cable of this embodiment includes an inner conductor 10, an insulating layer (not shown in the figure), and an outer conductor 20 arranged in sequence from the inside out; 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 slots 30 along the length direction of the spread-spectrum leaky cable, and the opening positions of the slots 30 correspond to the preset interval positions within the inner conductor corresponding to the center of the outer conductor or the outer conductor corresponding to the center of the outer conductor.

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

[0058] The first cross-sectional shape in this embodiment refers to the cross-sectional shape of the inner conductor 10 in a direction perpendicular to the length direction of the spread spectrum leaky cable, and can be circular, elliptical, or other non-circular structures having at least one inner conductor symmetry axis. The second cross-sectional shape refers to the cross-sectional shape of the outer conductor 20 in a direction perpendicular to the length direction of the spread spectrum leaky cable, and can be circular, elliptical, or other non-circular structures having at least one outer conductor symmetry axis. The coincident symmetry axis refers to those axes that are simultaneously the symmetry axes of the first cross-sectional shape of the inner conductor 10 and the second cross-sectional shape of the outer conductor 20. As Figure 2 shown in the spread spectrum leaky cable, if the second cross-sectional shape is circular and the first cross-sectional shape is a non-circular structure having only one inner conductor symmetry axis, then there is only one coincident symmetry axis perpendicular to the cable length direction. The preset number refers to the number of coincident symmetry axes of the inner and outer conductors 20 preset in advance according to specific application requirements and performance goals when designing the spread spectrum leaky cable. This number is a value greater than zero and less than or equal to a certain integer (such as 1, 2, etc.), and is used to control the electromagnetic characteristics of the cable, especially the propagation behavior of higher-order modes and the signal leakage mode. By separately setting the cross-sectional shapes of the inner conductor 10 and the outer conductor 20, the number of coincident symmetry axes can be adjusted, thereby controlling the propagation path of higher-order modes, reducing unwanted radiation, and improving the stability and directivity of signal transmission.

[0059] The slot 30 in this embodiment is an opening (which can be linear, spiral, or other shapes) periodically opened on the outer conductor 20 and is used to control the leakage of electromagnetic waves. The opening position of the slot 30 corresponds to the preset interval position range of the position of the outer conductor corresponding to the center of the inner conductor axis or the preset interval position range of the position of the outer conductor corresponding to the center of the outer conductor axis.

[0060] Specifically, the slot 30 can be opened within the range of ±30 mm of the position of the outer conductor corresponding to the long axis center of the outer conductor 20 or within the range of ±30 mm of the position of the outer conductor corresponding to the short axis center of the outer conductor 20; the slot 30 can also be opened within the range of ±30 mm of the position of the outer conductor corresponding to the long axis center of the inner conductor 10 or within the range of ±30 mm of the position of the outer conductor corresponding to the short axis center of the inner conductor 10. Among them, the slot 30 is preferably opened at the position where the distance between the inner and outer conductors is the smallest (the minimum radial difference between the inner conductor 10 and the outer conductor 20). Opening the slot 30 near the axis center and arranging it periodically along the length direction of the spread spectrum leaky cable can excite the strongest electric field and improve the signal transmission efficiency.

[0061] In some embodiments, the first cross-sectional shape and the second cross-sectional shape are respectively divided by a cross coordinate system into inner guiding parts in four quadrants and outer guiding parts in four quadrants. Each quadrant includes an inner guiding part or an outer guiding part. The inner guiding part and the outer guiding part refer to the divided parts of the cross-sections of the inner conductor 10 and the outer conductor 20 within the four quadrants. The inner guiding part and the outer guiding part include arc segments. The inner guiding eccentricity of each inner guiding part in the inner guiding parts in four quadrants and the outer guiding eccentricity of each outer guiding part in the outer guiding parts in four quadrants are both 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). Herein, the inner guiding eccentricity or the outer guiding eccentricity is a parameter used to describe the degree of deviation of the first cross-sectional shape or the second cross-sectional shape from a circle. The smaller the inner guiding eccentricity, the closer the arc segment in the corresponding inner guiding part approaches a circular arc. The smaller the outer guiding eccentricity, the closer the arc segment in the corresponding outer guiding part approaches a circular arc. By setting the first preset threshold and the second preset threshold, it is possible to avoid the cross-sectional shape from being too flat, thereby ensuring the mechanical strength and electromagnetic performance of the spread spectrum leaky cable.

[0062] Specifically, the inner guiding eccentricity is calculated by taking the square root of the absolute value of the difference between the square of the X-axis length and the square of the Y-axis length of the corresponding inner guiding part and then dividing by the larger value of the X-axis length and the Y-axis length.

[0063] Exemplarily, as Figure 3 shown, the eccentricity e of each inner guiding part i (i = 1, 2, 3, 4) is as shown in formula (1):

[0064]

[0065] wherein, a i ≥b i .

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

[0067] Similarly, it can be obtained that the outer guiding eccentricity is calculated by taking the square root of the absolute value of the difference between the squares of the X-axis length and the Y-axis length of the corresponding outer guiding part and then dividing by the larger value of the X-axis length and the Y-axis length. Exemplarily, the eccentricities Ei (i = 1, 2, 3, 4) of each outer guiding part are shown in formula (2):

[0068]

[0069] Among them, A i ≥B i .

[0070] For the first outer guiding part corresponding to the lower left part, A1 = AA1 + ΔA1, B1 = BB2 + ΔB1; for the second outer guiding part corresponding to the lower right part, A2 = AA2 + ΔA2, B2 = BB3 + ΔB2; for the third outer guiding part corresponding to the upper left part, A3 = AA3 + ΔA3, B3 = BB1 + ΔB3; for the fourth outer guiding part corresponding to 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 guiding part, B1 is the Y-axis length of the complete figure corresponding to the arc segment in the first outer guiding part, A2 is the X-axis length of the complete figure corresponding to the arc segment in the second outer guiding part, B2 is the Y-axis length of the complete figure corresponding to the arc segment in the second outer guiding part, A3 is the X-axis length of the complete figure corresponding to the arc segment in the third outer guiding part, B3 is the Y-axis length of the complete figure corresponding to the arc segment in the third outer guiding part, A4 is the X-axis length of the complete figure corresponding to the arc segment in the fourth outer guiding part, B4 is the Y-axis length of the complete figure corresponding to the arc segment in the fourth outer guiding part. ΔA1, ΔA2, ΔA3, ΔA4, ΔB1, ΔB3, ΔB2 and ΔB4 refer to the errors between the axis lengths of the complete figures corresponding to the arc segments in each outer guiding part and the axis lengths corresponding to the actually existing arc segments.

[0071] In one embodiment, as Figure 2 and Figure 4 shown, 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 inner guiding symmetry axis; the inner guiding eccentricities of at least two of the first inner guiding part, the second inner guiding part, the third inner guiding part and the fourth inner guiding part in the four-quadrant inner guiding part are greater than a preset third threshold value (such as 0.1), or at least two of the first inner guiding part, the second inner guiding part, the third inner guiding part and the fourth inner guiding part further include straight line segments. At this time, the first inner guiding eccentricity is equal to the second eccentricity, and the third inner guiding eccentricity is equal to the fourth eccentricity; and / or, the first inner guiding eccentricity is equal to the third eccentricity, and the second inner guiding eccentricity is equal to the fourth eccentricity.

[0073] In another embodiment, as Figure 5 and Figure 6 shown, 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 guiding symmetry axis; the outer guiding eccentricities of at least two of the first outer guiding part, the second outer guiding part, the third outer guiding part, and the fourth outer guiding part among the four-image outer guiding parts are greater than a preset third threshold (such as 0.1), or at least two of the first outer guiding part, the second outer guiding part, the third outer guiding part, and the fourth outer guiding part further include straight line segments. At this time, the first outer guiding eccentricity is equal to the second eccentricity, and the third outer guiding eccentricity is equal to the fourth eccentricity; and / or, the first outer guiding eccentricity is equal to the third eccentricity, and the second outer guiding eccentricity is equal to the fourth eccentricity.

[0075] In another embodiment, as Figure 7 and Figure 8 shown, 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 have at least one coincident symmetry axis; the inner guiding eccentricities of at least two of the first inner guiding part, the second inner guiding part, the third inner guiding part, and the fourth inner guiding part among the four-image inner guiding parts are greater than a preset third threshold (such as 0.1), or at least two of the first inner guiding part, the second inner guiding part, the third inner guiding part, and the fourth inner guiding part further include straight line segments; the outer guiding eccentricities of at least two of the first outer guiding part, the second outer guiding part, the third outer guiding part, and the fourth outer guiding part among the four-image outer guiding parts are greater than a preset third threshold, or at least two of the first outer guiding part, the second outer guiding part, the third outer guiding part, and the fourth outer guiding part further include straight line segments.

[0077] It should be noted that Figures 2 to 8 is just an example in the corresponding situation, and the cross-sectional shapes of the inner and outer conductors and the number of coincident symmetry axes do not impose any limitations on the embodiments of the present invention.

[0078] Based on the above various 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 (such as 0.94) and less than or equal to a fifth preset threshold (such as 1). The greater the concentricity, the higher the central coincidence degree 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. Specifically, as shown in formula (3):

[0079]

[0080] where C is the concentricity, h max is the maximum radial difference, h minis the minimum radial difference. By precisely 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, as Figure 9 shown, the two black solid dots in the figure respectively represent the centers of the first cross-sectional shape and the second cross-sectional shape. When both the first cross-sectional shape and the second cross-sectional shape are circular structures, the first cross-sectional shape and the second cross-sectional shape satisfy the following conditions:

[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 (such as 0) and less than the fourth preset threshold (such as 0.94). The greater the concentricity, the higher the coincidence degree of the centers 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 refers to formula (3), which will not be elaborated in this embodiment.

[0083] In addition, in order to ensure the signal transmission performance, it is necessary to match the impedance between the inner and outer conductors with the system impedance to ensure the system signal transmission. In some embodiments, in the case where the inner and outer conductors have two coincidence symmetry axes with different lengths, as Figure 3 shown, when the directions of the inner short axis of the inner conductor 10 and the outer short axis of the outer conductor 20 are the same, 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 in the long axis direction satisfies the following formula (5):

[0086]

[0087] where, 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 each outer conductor part in the long axis direction, aa i is the length of the arc segment in each inner conductor part in the long axis direction, BB i is the length of the arc segment in each outer conductor part in the short axis direction, bb i is the length of the arc segment in each inner conductor part in the short axis direction, ε r is the relative dielectric constant.

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

[0089]

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

[0091]

[0092] Where Z s is the system impedance, is the impedance between the inner conductor and the outer conductor in the major axis direction, is the impedance between the inner conductor and the outer conductor in the minor axis direction, AA i is the length in the major axis direction of the arc segment in each outer guide part, aa i is the length in the major axis direction of the arc segment in each inner guide part, BB i is the length in the minor axis direction of the arc segment in each outer guide part, bb i is the length in the minor axis direction of the arc segment in each inner guide part, ε r is the relative permittivity.

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

[0094] In the spread spectrum leaky cable proposed by the embodiments of the present application, by setting different cross-sectional shapes for the inner and outer conductors, the number of coincidence symmetry axes of the cross-sectional shapes of the inner and outer conductors is controlled not to exceed a preset number, so that the propagation path of the higher order mode is restricted and can only propagate along a small number of coincidence symmetry axis directions, making the mode field distribution and the transmission path more stable, avoiding the chaos of the field distribution and the deterioration of the signal. In addition, since the propagation path of the higher order mode is stabilized and the feeding is concentrated in a few directions, the signal leakage efficiency is improved, the wireless signal coverage effect can be optimized, and the high-frequency application performance of the leaky cable can be enhanced.

[0095] Those skilled in the art should understand that in the disclosure of this application, the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. This is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

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

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A spread spectrum leaky cable, characterized in that, The spread spectrum leaky cable includes an inner conductor, an insulating layer, and an outer conductor arranged in sequence from the inside out; The number of coincidence 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 slot holes along the length direction of the spread spectrum leaky cable, and the opening positions of the slot holes correspond to the preset interval position range of the position of the inner conductor axis center corresponding to the outer conductor, or the preset interval position range of the position of the outer conductor axis center corresponding to the outer conductor.

2. The spread spectrum leaky cable according to claim 1, characterized in that, The first cross-sectional shape and the second cross-sectional shape are respectively divided into four-quadrant inner conductor parts and four-quadrant outer conductor parts by a cross coordinate system. The inner conductor parts and the outer conductor parts include arc segments. The inner conductor eccentricities of each inner conductor part in the four-quadrant inner conductor parts and the outer conductor eccentricities of each outer conductor part in the four-quadrant outer conductor parts are both greater than or equal to a first preset threshold and less than or equal to a second preset threshold. Among them, the smaller the inner conductor eccentricity, the closer the arc segment in the corresponding inner conductor part is to a circular arc, and the smaller the outer conductor eccentricity, the closer the arc segment in the corresponding outer conductor part is to a circular arc.

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

4. The spread spectrum leaky cable according to claim 2, characterized in that, When the second cross-sectional shape is a circular structure, the first cross-sectional shape satisfies the following conditions: The first cross-sectional shape has at least one inner conductor symmetry axis; The inner conductor eccentricities of at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part in the four-quadrant inner conductor parts are greater than a preset third threshold, or at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part also include straight line segments.

5. The leaky cable according to claim 2, wherein When the first cross-sectional shape is a circular structure, the second cross-sectional shape satisfies the following conditions: The second cross-sectional shape has at least one outer conductor symmetry axis; The outer conductor eccentricities of at least two of the first outer conductor part, the second outer conductor part, the third outer conductor part, and the fourth outer conductor part in the four-quadrant outer conductor parts are greater than a preset third threshold, or at least two of the first outer conductor part, the second outer conductor part, the third outer conductor part, and the fourth outer conductor part also include straight line segments.

6. The spread spectrum leaky cable according to claim 2, wherein, The first cross-sectional shape and the second cross-sectional shape satisfy the following conditions: The first cross-sectional shape and the second cross-sectional shape have at least one coincidence symmetry axis; The inner conductor eccentricities of at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part in the four-quadrant inner conductor parts are greater than a preset third threshold, or at least two of the first inner conductor part, the second inner conductor part, the third inner conductor part, and the fourth inner conductor part also include straight line segments; The eccentricity of the outer conduction of at least two of the first outer conduction part, the second outer conduction part, the third outer conduction part, and the fourth outer conduction part in the four-image outer conduction part is greater than a preset third threshold value, or at least two of the first outer conduction part, the second outer conduction part, the third outer conduction part, and the fourth outer conduction part further include straight line segments.

7. The spread spectrum leaky cable according to any one of claims 4 to 6, 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 value and less than or equal to a fifth preset threshold value. The greater the concentricity, the higher the degree of coincidence of the centers 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.

8. The leaky cable according to claim 1, characterized in that, When both the first cross-sectional shape and the second cross-sectional shape are circular structures, the first cross-sectional shape and the second cross-sectional shape satisfy the following conditions: The concentricity of the first cross-sectional shape and the second cross-sectional shape is greater than or equal to a sixth preset threshold value and less than the fourth preset threshold value. The greater the concentricity, the higher the degree of coincidence of the centers 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.

9. The leaky cable according to claim 1, wherein 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 coincident symmetry axes with different lengths, when the directions of the inner conduction short axis of the inner conductor and the outer conduction short axis of the outer conductor are the same, the impedance between the inner conductor and the outer conductor in the short axis direction satisfies the following conditions: The impedance between the inner conductor and the outer conductor in the long axis direction satisfies the following conditions: Among them, 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 in the long axis direction of the arc segment in each outer conductor part, aa i is the length in the long axis direction of the arc segment in each inner conductor part, BB i is the length in the short axis direction of the arc segment in each outer conductor part, bb i is the length in the short axis direction of the arc segment in each inner conductor part, ε r is the relative permittivity.

10. The leaky cable according to claim 1, characterized in that, 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 coincident symmetry axes with different lengths, when the inner conduction short axis of the inner conductor and the outer conduction short axis of the outer conductor are orthogonal, the impedance between the inner conductor and the outer conductor in the short axis direction satisfies the following conditions: The impedance between the inner conductor and the outer conductor in the long axis direction satisfies the following conditions: Among them, 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 in the long axis direction of the arc segment in each outer guide part, aa i is the length in the long axis direction of the arc segment in each inner guide part, BB i is the length in the short axis direction of the arc segment in each outer guide part, bb i is the length in the short axis direction of the arc segment in each inner guide part, ε r is the relative permittivity.

Images