A low-loss leaky coaxial cable, its design method and manufacturing process

Abstract

This invention discloses a low-loss leaky coaxial cable, its design method, and manufacturing process, belonging to the field of communication cable technology. It includes the following steps: determining the operating frequency band of the leaky cable; opening slots of various hole types on the leaky cable, and designing the slot parameters for each hole type, wherein the slot parameters include the number of hole types m, pitch P, number of slots n, and slot length l; determining the frequency point F of the leaky cable with various hole types. j Transmission attenuation value a ij and coupling loss value c ij Based on the requirement of balanced overall loss performance of leaky cables at different axial length positions, and according to the frequency F of various hole structure leaky cables... j Transmission attenuation value a ij and coupling loss value c ij Calculate the frequency F of leaky cables with various aperture structures. j Application length L ij Based on the design requirements of the working scenario, this invention designs slots with specific parameters on the leaky cable using theoretical calculation formulas, so that the designed low-loss leaky cable can achieve better signal uniformity and meet the requirements of uniform signal coverage.

Description

Technical Field

[0001] This invention belongs to the field of communication cable technology, and specifically relates to a low-loss leaky coaxial cable and its design method and manufacturing process. Background Technology

[0002] Leaky coaxial cable is a type of communication cable that can be used for both signal transmission and reception. It is commonly used for signal coverage in narrow areas such as subways and high-speed rail tunnels. Its structure is as follows: Figure 1 As shown, it consists of an inner conductor 1, a foamed insulating layer 2, an outer conductor 4 with slots 3, and a sheath layer 5. Signal transmission and reception are achieved through the slots 3 on the outer conductor.

[0003] Currently, mobile communication wireless coverage in enclosed and narrow areas such as subways and high-speed rail tunnels mostly uses conventional leaky cables with a single slotted structure or low-loss leaky cables using combinations of 2-4 different slotted structures. Conventional leaky cables with a single slotted structure exhibit significant signal fluctuations throughout the coverage area, especially at the beginning and end, resulting in strong signals near the equipment and weak signals further away, leading to signal waste. For example, the overall loss curve of a 50-32 leaky cable with a single slotted structure in the 2.6GHz band is as follows... Figure 2 As shown, it can be observed that the overall loss gradually increases with increasing length, and the signal strength difference between the beginning and end is large. Low-loss leaky cables employing 2-4 different slotting structures typically combine leaky cable structures with different transmission attenuation and coupling loss values. The near end, closer to the base station equipment, uses a structure with lower transmission attenuation and correspondingly higher coupling loss to reduce power waste; the far end, farther from the equipment, uses a structure with higher transmission attenuation and correspondingly lower coupling loss to achieve comparable signal strength at both ends. For example, the overall loss curve of a 50-32 leaky cable with four different slotting configurations (slotting configurations using the same pitch, pitch P = 185mm, 8 slots per type, slot angle of 20 degrees, and slot lengths of 16 / 18 / 19 / 20mm) in the 2.6GHz band is shown in the figure. Figure 3 As shown, it can be observed that its comprehensive loss index is relatively high. Figure 2 While the signal coverage is more uniform, the drop at the transition points between different aperture types is significant, leaving considerable room for improvement in overall loss uniformity. In conclusion, existing leaky cable designs still struggle to achieve uniform signal coverage, and the overall loss performance of leaky cables requires further improvement.

[0004] Therefore, there is a need to develop low-loss leaky cables with more combinations of aperture structures to achieve better signal uniformity. However, currently, there is a lack of theoretical research and scientific design for different aperture combinations in low-loss leaky cables, making the design process very difficult. Furthermore, current leaky cable outer conductor processing generally uses a punching method, where the aperture shape is determined by a predetermined die. For the production of low-loss leaky cables, the outer conductor is produced using different aperture splicing methods. Due to considerations of production line speed and operator workload, the length of each structure generally needs to be greater than 60 meters. This significantly limits the number of slotted structures in a single low-loss leaky cable, making it difficult to achieve optimal performance.

[0005] Therefore, this invention proposes a design method and manufacturing process for low-loss leaky coaxial cables suitable for multi-slot structure combinations, aiming to optimize the overall loss performance of low-loss leaky cables. Summary of the Invention

[0006] The main objective of this invention is to provide a low-loss leaky coaxial cable employing a combination of various hole structures, along with its design method and manufacturing process. By combining leaky cables with different transmission attenuation and coupling loss indices using a fitting formula, the overall loss performance of the low-loss leaky cable of this invention is more uniform and tends to be balanced at different axial length positions. This ensures that the signal strength radiated from the leaky cable received by the mobile terminal at different axial positions is relatively consistent. Furthermore, the manufacturing process of this invention can solve the production and processing problems of low-loss leaky cables with five or more multi-slot combinations that cannot be addressed by current traditional stamping methods.

[0007] To achieve the above objectives, the present invention provides a design method for a low-loss leaky coaxial cable, comprising the following steps: determining the operating frequency band of the leaky cable; Various hole types are made in the leaky cable, and the slot parameters of each hole type are designed. The slot parameters include the number of hole types m, the pitch P, the number of slots n, and the slot length l. Determine the frequency F of various hole-type leaky cables. j Transmission attenuation value a ij and coupling loss value c ij ; Based on the requirement of balanced overall loss performance of leaky cables at different axial length positions, and according to the frequency F of various hole-type leaky cables... j Transmission attenuation value a ij and coupling loss value c ij Calculate the frequency F of leaky cables with various aperture structures. j Application length L ij .

[0008] Furthermore, the frequency F of various aperture structure leaky cables is calculated according to the following formula (1).j Application length L ij : (1); in, For structure i, the leaky cable is in F j Frequency usage duration; For structure i, the leaky cable is in F j Frequency coupling loss value; For the leaky cable of structure i-1 at F j Frequency coupling loss value; For structure i, the leaky cable is in F j Frequency attenuation value.

[0009] Furthermore, various aperture-type leaky cables at frequency F j Transmission attenuation value a ij and coupling loss value c ij The following requirements must be met: Along the signal transmission direction of the leaky cable, the coupling loss value of each aperture structure leaky cable is less than or equal to the coupling loss value of the previous aperture structure leaky cable, that is... ; Along the signal transmission direction of the leaky cable, the transmission attenuation value of each aperture structure leaky cable is greater than or equal to the transmission attenuation value of the previous aperture structure leaky cable, that is... .

[0010] Furthermore, the coupling loss difference between adjacent hole-type leaky cables is within the range of 0-6dB, i.e. .

[0011] Furthermore, the design pitch P must meet the following requirements: the pitch P values ​​of each hole type structure should be relatively consistent, and the deviation of each pitch P value should not exceed 2%.

[0012] Furthermore, based on the lowest operating frequency F1 and the highest operating frequency F2 of the leaky cable operating frequency band, the pitch P and the number of slots n for each hole type are determined according to the following formulas (2) and (3): (2); (3); in, This is the lowest operating frequency for the leaky cable; This is the highest operating frequency of the leaky cable; P is the speed of light; P is the slot pitch. is the equivalent dielectric constant; n is the number of slots.

[0013] Furthermore, based on the coupling loss value c of the leaky cable with each aperture structure... ij The groove length of each hole structure is determined according to the following formula (4). : (4); Where A and B are constants; For structure i, the leaky cable is in F j Frequency coupling loss value; l i The slot length of the leaky cable in structure i is... The slot angle is for the leaky cable of structure i.

[0014] Furthermore, the number m of the hole type is determined using the following formula (5): (5); Where m is the number of hole types, which is an integer; This is an integer function that rounds to the nearest integer. This is the difference between the maximum and minimum coupling loss of the leaky cable. This represents the design value for the coupling loss tolerance of adjacent aperture structures.

[0015] In another aspect, the present invention provides a low-loss leaky coaxial cable designed using the aforementioned low-loss leaky coaxial cable design method.

[0016] In another aspect, the present invention provides a manufacturing process for the aforementioned low-loss leakage coaxial cable, comprising the following steps: The metal strip is released and corrected through the unwinding and correction systems; The tension and linear speed of the metal strip are controlled by a tension adjustment system; A laser cutting system is used to create slots with various hole structures on a metal strip according to a preset program; The quality of slot and hole processing is inspected online using a vision inspection system. If the inspection requirements are not met, an alarm is triggered and the location of the abnormality is recorded. The slotted metal strip is longitudinally wrapped to form an outer conductor; The low-loss leaky coaxial cable is obtained by corrugating and longitudinally wrapping a sheath layer on the outer conductor and then winding it up.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention creatively proposes a design method for low-loss leaky coaxial cables. Based on the design requirements of the working scenario, specific parameter slot structures are designed on the leaky cable using theoretical calculation formulas to achieve better signal uniformity and meet the requirement of uniform signal coverage. Specifically, by designing leaky cables with various transmission attenuation and coupling loss values ​​using formula (1) proposed in this invention, the application length of each slot structure at each frequency point is calculated. This makes the overall loss performance of the low-loss leaky cable more uniform at different axial length positions and tends to be balanced overall, ensuring that the signal strength radiated from the leaky cable received by the mobile terminal at different axial positions is relatively consistent.

[0018] Furthermore, the manufacturing process of this invention can solve the production and processing of low-loss leaky cables with five or more multi-slot combinations that cannot be solved by the current traditional punching processing method, and meet the processing requirements of the low-loss leaky cable of this invention for any hole type, so as to realize the final production and application of the designed product. Attached Figure Description

[0019] Figure 1 A schematic diagram of the existing leaky cable structure is shown; Figure 2 The diagram shows the overall loss test results of an existing 50-32 leaky cable using a single slot at 2.6 GHz. Figure 3 The diagram shows the overall loss test results of an existing 50-32 low-loss leaky cable using four different aperture combinations at 2.6 GHz. Figure 4 The coupling loss test diagram of a 50-42 leaky cable with a pitch P=250mm at 2.6GHz is shown; Figure 5 The diagram shows the overall loss test of the 50-42 leaky cable at 2.6 GHz when the adjacent aperture pitch deviation ΔP = 10%P. Figure 6 A schematic diagram of the leakage cable radiation angle characteristics is shown; Figure 7 The diagram shows the overall loss test results of the 50-42 leaky cable at 2.6GHz using 12 different aperture designs according to the present invention. Figure 8 A schematic diagram of the process structure for manufacturing the low-loss leakage coaxial cable of the present invention is shown. Figure 9 A schematic diagram of the slot variable parameters is shown.

[0020] The above-mentioned figures include the following reference numerals: 1. Inner conductor; 2. Foamed insulation layer; 3. Slot; 4. Outer conductor; 5. Sheath layer. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0022] To achieve the above objectives, embodiments of the present invention provide a design method for a low-loss leakage coaxial cable, comprising the following steps: Determine the operating frequency band of the leaky cable; Various hole types are made in the leaky cable, and the slot parameters of each hole type are designed. The slot parameters include the number of hole types m, the pitch P, the number of slots n, and the slot length l. Determine the frequency F of various hole-type leaky cables. j Transmission attenuation value a ij and coupling loss value c ij ; Based on the requirement of balanced overall loss performance of leaky cables at different axial length positions, and according to the frequency F of various hole-type leaky cables... j Transmission attenuation value a ij and coupling loss value c ij Calculate the frequency F of leaky cables with various aperture structures. j Application length L ij .

[0023] In a preferred embodiment of the present invention, the frequency F of various aperture structure leaky cables is calculated according to the following formula (1). j Application length L ij : (1); in, For structure i, the leaky cable is in F j Frequency usage duration; For structure i, the leaky cable is in F j Frequency coupling loss value; For the leaky cable of structure i-1 at F j Frequency coupling loss value; For structure i, the leaky cable is in F j Frequency attenuation value.

[0024] This invention designs various types of leaky cables with different transmission attenuation and coupling loss values ​​using formula (1) of this invention, which can quickly calculate the frequency F of various hole-type leaky cables. j The application length ultimately achieves frequency point F. j The overall loss S at different axial positions L of the leaky cable ij It has a relatively optimal value. This design allows for a relatively uniform overall loss across different frequencies in various mobile communication systems, reducing signal power waste and achieving a longer coverage distance. Specifically, for frequency point F...j Overall loss at application length L It can be calculated using the following formula (6): (6).

[0025] In a preferred embodiment of the present invention, various aperture structure leaky cables at frequency F j Transmission attenuation value a ij and coupling loss value c ij The following requirements must be met: Along the signal transmission direction of the leaky cable, the coupling loss value of each aperture structure leaky cable is less than or equal to the coupling loss value of the previous aperture structure leaky cable, that is... ; Along the signal transmission direction of the leaky cable, the transmission attenuation value of each aperture structure leaky cable is greater than or equal to the transmission attenuation value of the previous aperture structure leaky cable, that is... .

[0026] To ensure a more uniform overall loss at various frequency points Fj at different application length positions L, in a preferred embodiment of the present invention, the coupling loss difference between adjacent aperture structure leaky cables is within the range of 0-6dB, i.e. More preferably, .like Figure 4 Taking the coupling loss test diagram of a 50-42 specification leaky cable with a pitch P=250mm at 2.6GHz as an example, the fluctuation range of its coupling loss is 3-15dB. Since the coupling loss of various existing radial leaky cables is affected by structural design and testing environment, its fluctuation range is generally 3-15dB. To further prevent poor communication performance of mobile terminals when passing through leaky cables with different aperture structures due to excessive signal drop, this invention controls the coupling loss difference between adjacent leaky cable aperture structures to be within the range of 0-6dB, and designs the aperture structure based on this requirement.

[0027] As a further preferred embodiment, when the design method of the low-loss leaky coaxial cable of the present invention is applied to low-loss leaky cables of specifications 50 (nominal characteristic impedance)-32 (equivalent insulation outer diameter of cable) and 50 (nominal characteristic impedance)-42 (equivalent insulation outer diameter of cable),... Recommended values ​​are shown in Table 1 below. For low-loss leaky cables of specification 50-32, the application length of various hole types should be 8-75m; for low-loss leaky cables of specification 50-42, the application length of various hole types should be 10-100m.

[0028] Table 1: Recommended Application Lengths for Various Hole Types of 50-32 / 42 Low-Loss Leakage Cables

[0029] In a preferred embodiment of the present invention, the pitch P value of the slotted hole type of the outer conductor of the leaky cable with different hole type combinations selected in the present invention should be relatively consistent. More preferably, the deviation of the P value should not exceed 2%. This is because when the P values ​​are inconsistent, the radiation angles at each frequency point will become different. When the signal propagates in space, the propagation direction is inconsistent. Beyond a certain radial distance, signal peaks and valleys are prone to superposition, leading to signal attenuation. Conversely, signal peak superposition can produce signal amplification, thus causing greater signal fluctuations and affecting communication quality. Figure 5 As shown in the figure, the comprehensive loss test diagram of the 50-42 leaky cable at 2.6GHz when the adjacent aperture pitch deviation ΔP=10%P shows that the signal fluctuation in the middle section is relatively large.

[0030] This embodiment uses a low-loss leaky cable for civilian communication as an example, with a slot nominal pitch of P=250mm. Since the lower the frequency, the larger the radiation angle, the greater the radial distance X from the signal overlap point of adjacent slots to the leaky cable. The schematic diagram of the radial distance X is shown below. Figure 6 As shown in Table 2, this embodiment mainly considers the highest operating frequency of 3.6 GHz.

[0031] Table 2: Pitch and Radiation Angle Correspondence Table

[0032] refer to Figure 6 It can be seen that the interference is greatest when the signals generated by adjacent slots overlap. At this time, X=9636mm can be calculated. Leaky cables are generally suitable for narrow and enclosed areas, such as subways, high-speed rail tunnels, elevator shafts, mines, etc. The width of the space is generally no more than 10m. Therefore, the deviation of the P value as the preferred option should not exceed 2%.

[0033] like Figure 7 The figure shows the overall loss test results of a 50-42 leaky cable designed and manufactured using 12 different hole structure combinations with a nominal pitch of P=250mm and a P value deviation of no more than 0.5% at 2.6GHz. The figure shows that its overall loss performance over a length of 340m is comparable to... Figure 5 It is significantly more uniform.

[0034] Due to the operating frequency band F of the slotted leaky cable and the coupling loss of the leaky cable of each slot structure... It is related to the hole pitch P, the number of slots n (referring to the number of slots in each hole structure), the slot length L, and the slot angle θ. Among them, the pitch P and the number of slot pairs n are related to the working frequency F of the leaky cable (F1≤F≤F2). The lowest working frequency F1 of the leaky cable working frequency band satisfies the following formula (2), and the highest working frequency F2 satisfies the following formula (3).

[0035] Therefore, based on the lowest operating frequency F1 and the highest operating frequency F2 of the leaky cable operating frequency band, the pitch P and the number of slots n for each hole type are determined according to the above formulas (2) and (3).

[0036] (2); (3); in, This is the lowest operating frequency for the leaky cable; This is the highest operating frequency of the leaky cable; P is the speed of light; P is the slot pitch. is the equivalent dielectric constant; n is the number of slots.

[0037] Among them, the groove length of each hole structure and slot angle With coupling loss The relevant relationships are satisfied as follows (4). Therefore, the slot length of each hole structure is determined based on the above formula (4). .

[0038] (4); Among them, A and B are constants that are related to frequency, slot pitch, slot angle and number of holes, and are generally obtained through laboratory testing. For structure i, the leaky cable is in F j Frequency coupling loss value; l i The slot length of the leaky cable in structure i is... The slot angle for the leaky cable of structure i is generally set to 15-30° based on empirical theoretical values.

[0039] Based on optimizing the full-band radiation performance, the coupling loss of the leaky cable is made relatively uniform and the coverage is continuous. The number of aperture structures m (i.e., the number of different aperture types) can be calculated using formula (5): (5); Where m is the number of hole types, which is an integer; This is an integer function that rounds to the nearest integer. This is the difference between the maximum and minimum coupling loss of the leaky cable. This represents the design value for the coupling loss tolerance of adjacent aperture structures.

[0040] The number of perforated structures is generally designed based on the coupling loss tolerance of adjacent perforated structures. This design method can be based on a 2dB coupling loss tolerance, which is the reference median value of adjacent perforated structures. If a more precise design is required, a tolerance value of 1-2dB can be used. The required number of perforated structures is calculated based on the difference between the maximum and minimum coupling loss of the leaky cable. For example, if the difference between the maximum and minimum coupling loss of a 300-meter leaky cable of a certain specification at a frequency of 3500MHz is 24dB, and a 2dB tolerance is preferred for the design, the required number of perforated structures, m, is 24 / 2+1=12.

[0041] A second aspect of the present invention provides a low-loss leaky coaxial cable designed using the aforementioned low-loss leaky coaxial cable design method.

[0042] A third aspect of the present invention provides a manufacturing process for the aforementioned low-loss leakage coaxial cable, the specific process of which is as follows: Figure 8 As shown, the specific steps are as follows: Step 1: Unwinding and correction: Release the metal strip (usually copper or aluminum strip) through the unwinding system and correction system and perform correction; Step 2: Tension and linear speed adjustment: The tension and linear speed of the metal strip are controlled by the tension adjustment system to avoid unwinding fluctuations affecting the flatness of the subsequent metal strip. Step 3: Laser grooving: The laser cutting system is used to create various hole structures on the metal strip according to the preset program. Specifically, the laser cutting system performs hole drilling on the metal strip according to the meter data. The required hole type is set by the program. During the processing, the required processing structure can be flexibly called according to the set program. At the same time, the material receiving system completes the functions of picking up waste materials and smoke.

[0043] Step 4: Visual inspection: The quality of the slot and hole processing is inspected online using a visual inspection system. If the inspection requirements are not met, an alarm is triggered and the location of the abnormality is recorded. Step 5: Post-processing: The slotted metal strip is longitudinally wrapped to form an outer conductor, and corrugated and longitudinally wrapped with a sheath layer are performed on the outer conductor. The low-loss leaky coaxial cable is obtained by winding.

[0044] The low-loss leaky coaxial cable of this invention employs intelligent laser cutting technology for slotting the outer conductor. Through program control, various desired slot shapes can be engraved on the same metal strip at any time, satisfying the processing requirements of the low-loss leaky cable of this invention for any hole type. For example... Figure 9 The structural diagram of the slot variable parameters shows that the slot parameters for each slot type include, for example, the number of slot groups m, pitch P, number of slots n per group, slot length L, slot width k, slot chamfer R, slot angle a, and spacing P between slots. i(i=n-1) is designed as a variable, and the hole shape parameters are set by the software and processed by intelligent laser cutting equipment.

[0045] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0046] Example Aperture design was conducted using a 50-42 specification low-loss leaky cable with an operating frequency band of 700-2700MHz, focusing primarily on the 2.6GHz band. Twelve aperture types were designed, and their parameters were measured. Furthermore, the overall loss test results for this low-loss leaky cable design at 2.6GHz are shown in the following figure. Figure 7 As shown.

[0047] (1) The process of determining the pitch P in this embodiment is as follows: based on the set target minimum operating frequency F1, and according to the above formula (2), the value of P is calculated; (2) The process of determining the number of slots n in this embodiment is as follows: based on the set target minimum working frequency F1 and target maximum working frequency F2, and according to the above formula (3), the value of n is calculated; (3) The process of determining the slot length l in this embodiment is as follows: based on the set coupling loss values ​​of each structural target, the slot length l is calculated according to the above formula (4); (4) The process of determining the slot angle θ in this embodiment is as follows: The slot angle is designed based on the space available for the slots on the metal strip. To prevent the slots from deforming during production, it is necessary to ensure that the metal strip connection width between any two adjacent slots is not less than 2mm. Based on experience, the angle θ is generally set to 15-30°. If the slot angle is too large, the non-major polarized signal components will be too large. If the slot angle is too small, the metal strip connection width between adjacent slots will be too small, which will easily cause the slots to deform during production and affect performance. Therefore, this embodiment is designed based on comprehensive performance and processing reliability. The slots 1#-6# are designed with an angle of 18°, the slots 7#-10# are designed with an angle of 23°, and the slots 11#-12# are designed with an angle of 25°.

[0048] (5) The process of determining the slot width w in this embodiment is as follows: the slot width does not affect the main polarization direction signal. Based on experience, the slot width w is generally designed to be between 1-5mm. In this embodiment, it is designed to be 3.5mm. (6) The process of determining the chamfer R in this embodiment is as follows: The chamfer is mainly for the convenience of production and processing. It is generally designed to be greater than or equal to 0.5 mm and less than or equal to half the groove width. In this embodiment, it is designed to be 1 mm.

[0049] (7) The transmission attenuation value a of various aperture structure leaky cables in this embodiment at 2.6GHz ij and coupling loss value c ijThe determination process is as follows: Based on experience, when the coupling loss is less than 60dB, the attenuation increases sharply. This embodiment is designed with a minimum coupling loss of about 60.5dB. The maximum coupling loss is set to 77dB according to engineering needs. With an average drop of 1.5dB, 12 structures can be calculated by (77-60.5)÷1.5+1=12. The attenuation corresponding to each structure is the transmission attenuation test value of the cable corresponding to the coupling loss value.

[0050] (8) The application length L of various hole-type structure leaky cables in this embodiment at a frequency of 2.6GHz ij The determination process is as follows: based on the set coupling loss values ​​of each structural target, the groove length l is calculated according to the above formula (4), and then fine-tuned according to the test values ​​of the sample. Its main focus frequency band is 2.6GHz. The parameters of each hole type are shown in Table 3 below. The transmission attenuation and coupling loss values ​​of the leaky cable of hole type 1-12# were tested, and the length of each structure can be calculated by formula (1) based on the tested values, as shown in Table 4.

[0051] Table 3: Parameters of 12 structural hole types for 50-42 low-loss leaky cable

[0052] Table 4: Application Lengths of 12 Structures for 50-42 Low-Loss Leakage Cable

[0053] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A design method for a low-loss leaky coaxial cable, characterized in that, Includes the following steps: Determine the operating frequency band of the leaky cable; Various hole types are made in the leaky cable, and the slot parameters of each hole type are designed. The slot parameters include the number of hole types m, the pitch P, the number of slots n, and the slot length l. determining the transmission attenuation value a j and the coupling loss value c ij of various hole structure leaky cables at frequency point F ij ; Based on the requirement of balanced overall loss performance of leaky cables at different axial length positions, and according to the frequency F of various hole-type leaky cables... j Transmission attenuation value a ij and coupling loss value c ij The leakage cable of various aperture structure at frequency F is calculated according to the following formula (1). j Application length L ij : （1）； in, For structure i, the leaky cable is in F j Frequency usage duration; For structure i, the leaky cable is in F j Frequency coupling loss value; For the leaky cable of structure i-1 at F j Frequency coupling loss value; For structure i, the leaky cable is in F j Frequency transmission attenuation value, where i is the sequence number of various hole types in the leaky cable, and j is the frequency sequence number of the leaky cable.

2. The design method for a low-loss leaky coaxial cable according to claim 1, characterized in that, Various hole-type leaky cables at frequency F j Transmission attenuation value a ij and coupling loss value c ij The following requirements must be met: Along the signal transmission direction of the leaky cable, the coupling loss value of each aperture structure leaky cable is less than or equal to the coupling loss value of the previous aperture structure leaky cable, that is... ; Along the signal transmission direction of the leaky cable, the transmission attenuation value of each aperture structure leaky cable is greater than or equal to the transmission attenuation value of the previous aperture structure leaky cable, that is... .

3. The design method for a low-loss leaky coaxial cable according to claim 2, characterized in that, The coupling loss difference between adjacent hole-type leaky cables is within the range of 0-6dB, i.e. .

4. The design method for a low-loss leaky coaxial cable according to claim 1, characterized in that, The design pitch P must meet the following requirements: the pitch P values ​​of each hole type structure should be relatively consistent, and the deviation of each pitch P value should not exceed 2%.

5. The design method for a low-loss leaky coaxial cable according to claim 1 or 4, characterized in that, Based on the lowest operating frequency F1 and the highest operating frequency F2 of the leaky cable operating frequency band, the pitch P and the number of slots n for each hole type are determined according to the following formulas (2) and (3): （2）； （3）； in, This is the lowest operating frequency for the leaky cable; This is the highest operating frequency of the leaky cable; P is the speed of light; P is the slot pitch. is the equivalent dielectric constant; n is the number of slots.

6. The design method for a low-loss leaky coaxial cable according to claim 1, characterized in that, Based on the coupling loss value c of the leaky cable with various aperture structures ij The groove length of each hole structure is determined according to the following formula (4). : （4）； Where A and B are constants; For structure i, the leaky cable is in F j Frequency coupling loss value; l i The slot length of the leaky cable in structure i is... The slot angle is for the leaky cable of structure i.

7. The design method for a low-loss leaky coaxial cable according to claim 1, characterized in that, The number of holes, m, is determined using the following formula (5): （5）； Where m is the number of hole types, which is an integer; This is an integer function that rounds to the nearest integer. This is the difference between the maximum and minimum coupling loss of the leaky cable. This represents the design value for the coupling loss tolerance of adjacent aperture structures.

8. A low-loss leaky coaxial cable, characterized in that, The design method of the low-loss leaky coaxial cable according to any one of claims 1 to 7 is used.

9. A manufacturing process for a low-loss leakage coaxial cable as described in claim 8, characterized in that, Includes the following steps: The metal strip is released and corrected through the unwinding and correction systems; The tension and linear speed of the metal strip are controlled by a tension adjustment system; A laser cutting system is used to create slots with various hole structures on a metal strip according to a preset program; The quality of slot and hole processing is inspected online using a vision inspection system. If the inspection requirements are not met, an alarm is triggered and the location of the abnormality is recorded. The slotted metal strip is longitudinally wrapped to form an outer conductor; The low-loss leaky coaxial cable is obtained by corrugating and longitudinally wrapping a sheath layer on the outer conductor and then winding it up.

Images