Ultrahigh-frequency low-loss longitudinal-hole PTFE insulated coaxial cable

Abstract

The invention relates to the technical field of cables, in particular to an ultrahigh-frequency low-loss longitudinal-hole PTFE insulated coaxial cable which comprises a composite conductive bar, a silver-plated copper flat belt, a PTFE insulating layer, a corrugated aluminum belt shielding layer and a sheath layer which are sequentially connected in a sleeved mode from inside to outside. Four identical longitudinal holes are formed in the PTFE insulating layer, and each longitudinal hole penetrates through the PTFE insulating layer along the extension direction of the PTFE insulating layer; each longitudinal hole is in a crescent shape; the longitudinal holes are distributed at equal intervals in the circumferential direction of the PTFE insulating layer; and each longitudinal hole is formed in the edge area, close to the outer ring, of the PTFE insulating layer. According to the cable, the transmission efficiency is improved by reducing signal attenuation, the service life is prolonged by improving the temperature resistance level, the inner conductor and the outer conductor are structurally adjusted to ensure that the cable has certain flexibility, and energy conservation and environmental protection are achieved by reducing the use amount of rare metal.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to an ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable. Background Art

[0002] Traditional high-frequency coaxial cables mostly use foamed polyethylene as the insulation layer, which has the advantages of low cost and small dielectric loss factor after foaming (about 1×10 -4 -1.5×10 -4 However, the cutoff frequency of this type of cable is usually below 6 GHz. In high-frequency scenarios, especially in millimeter-wave scenarios of 10 GHz and above, and in ultra-high-frequency scenarios such as aerospace, military, and defense, the dielectric loss increases significantly, resulting in severe signal attenuation. Furthermore, its temperature resistance is only -40 to +80°C, making it difficult to meet the requirements of use in complex environments. There are still coaxial cables that use FEP as the insulation layer, and its dielectric loss factor is about 2×10 -4 After foaming, the dielectric loss factor of PE is slightly lower than that of polyethylene foam. However, as the frequency increases, its dielectric loss factor increases rapidly and may even exceed that of polyethylene foam, making it unsuitable for high-frequency communication scenarios. Furthermore, its temperature resistance is approximately -40°C to +125°C, which limits its application in high-end applications such as aerospace, which require high temperature resistance. To address these issues, one approach is to use PTFE as the insulation layer. This improvement improves temperature resistance, but it also presents several challenges: Firstly, the solid structure results in a heavier cable, making it difficult to effectively control costs; secondly, the dielectric loss factor (DFT) in transmission performance is similar to that of expanded polyethylene (PE), leaving room for further optimization. These two issues limit the application of this cable in applications where weight, cost, and dielectric loss are crucial.

[0003] Therefore, how to solve the above-mentioned deficiencies in the prior art has become the subject to be studied and solved by the present invention. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: An ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable, comprising a composite conductive rod, a silver-plated copper flat tape, a PTFE insulation layer, a corrugated aluminum tape shielding layer and a sheath layer, which are sequentially sleeved from the inside to the outside; The PTFE insulating layer is provided with four identical longitudinal holes, each of which penetrates the PTFE insulating layer along an extension direction of the PTFE insulating layer; Each of the longitudinal holes is crescent-shaped; The longitudinal holes are equidistantly distributed in the circumferential direction of the PTFE insulating layer; Each of the vertical holes is arranged on the edge area of ​​the PTFE insulation layer close to the outer ring.

[0006] The PTFE insulation layer has insulating properties, and its attenuation constant remains almost unchanged at high temperatures, thereby ensuring the temperature resistance level of the cable in this embodiment and enabling the cable in this embodiment to meet the signal transmission requirements under high temperature conditions.

[0007] By opening vertical holes in the PTFE insulation layer, the weight of the insulation layer and thus the cable can be reduced, and the signal attenuation can be reduced by reducing dielectric loss.

[0008] The four vertical holes provide 360° mechanical support, ensuring the cable maintains structural stability under dynamic conditions such as bending and swaying. Tests have shown that after 500,000 bends, the four-hole structure can ensure minimal degradation in attenuation, characteristic impedance, and return loss, ensuring effective signal transmission. This indicates that the four-hole structure achieves a balance between mechanical support and transmission characteristics. Tests have shown that the dielectric loss under the four-hole structure is approximately 0.7×10 -4 When using a three-hole structure, although the mechanical support strength is sufficient, the dielectric loss is 5% higher than that of a four-hole structure, resulting in higher attenuation; under a five-hole structure, although the dielectric loss is 6% lower than that of a four-hole structure, the mechanical support capacity is reduced, which easily leads to damage and breakage of the insulation layer.

[0009] Compared to fan-shaped or semicircular holes, the crescent-shaped vertical holes create smaller gaps. While this increases the dielectric loss of the insulation layer, it also improves the mechanical support of the insulation layer, achieving a balance between dielectric loss and mechanical support. If a fan-shaped or semicircular hole is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edge, which can easily lead to mechanical support failure, insulation cracking, and ultimately distortion of the cable's overall characteristic impedance.

[0010] The longitudinal holes are evenly distributed in the circumferential direction of the PTFE insulation layer, so that the insulation layer is more evenly stressed and supported in the circumferential direction, reducing the risk of cracking or deformation of the insulation layer and extending the overall service life.

[0011] The core area of ​​the PTFE insulation layer (near the inner ring) is the key location for electric field, stress or dielectric transmission. Placing the longitudinal holes in the edge area of ​​the PTFE insulation layer near the outer ring can avoid damaging the material continuity of the core area and ensure that the insulation strength of the central part of the insulation layer is not affected by the holes.

[0012] In some embodiments, a highly conductive carbon fiber rod, also known as a composite conductive rod, is formed by combining metal-coated carbon fibers (to enhance conductivity) with a high-heat-resistant resin (such as polyimide). This composite conductive rod serves as the main inner conductor. In existing technology, inner conductors typically use pure copper or copper-clad aluminum, which suffer from excessive attenuation, high weight, and waste of non-ferrous metal resources. Composite conductive rods avoid these issues. In this embodiment, the inner conductor is formed by wrapping a silver-plated copper ribbon around the outer surface of the highly conductive carbon fiber rod. After sintering, the resulting metal fiber composite conductor exhibits high conductivity, high tensile strength, and resistance to bending fatigue.

[0013] Existing technologies typically use a tinned or silver-plated copper wire braid instead of silver-plated copper tape. This can lead to signal leakage through the braided layer, which can easily generate electromagnetic interference. Some existing technologies use aluminum foil, which, while achieving 100% coverage, has low shielding efficiency and is not heat-resistant.

[0014] In existing technology, corrugated copper tubes or smooth copper tubes are generally used as outer conductors. While this can improve cable performance, it is very expensive and the high copper density makes the cable heavier. This embodiment avoids these problems by using a corrugated aluminum tape shield as the outer conductor. Alternatively, the corrugated aluminum tape outer conductor shield can be formed by longitudinally wrapping the aluminum tape through a welding process and then shaping it with a roller.

[0015] It should be added that the inner conductor adopts a structure of silver-plated copper flat tape wrapped around a composite conductive rod. Compared with solid metal (such as copper-clad aluminum or copper-clad steel), the hardness is significantly reduced, which improves the flexibility of the cable. The outer conductor adopts a corrugated aluminum tape structure, which can improve the flexibility compared with the copper tube.

[0016] In summary, the cable in this embodiment improves transmission efficiency by reducing signal attenuation, extends service life by improving temperature resistance, ensures cable flexibility through structural adjustments to the inner and outer conductors, and achieves energy conservation and environmental protection by reducing the use of rare metals. The cable in this embodiment weighs only 50-60% of a similar copper-clad aluminum physically foamed insulated coaxial cable, reducing weight while also saving copper.

[0017] In a further technical solution, the PTFE insulation layer and the corrugated aluminum tape shielding layer enclose each of the longitudinal holes. With this arrangement, portions of the corrugated aluminum tape shielding layer form the walls of each longitudinal hole in the radial direction of the cable. Compared to forming each longitudinal hole with the PTFE insulation layer alone, this arrangement reduces the difficulty of creating each longitudinal hole, particularly when the holes must be continuously adjusted during creation to achieve a predetermined shape.

[0018] According to a further technical solution, each of the longitudinal holes is a centrally symmetrical structure, which reduces the difficulty of opening each longitudinal hole and facilitates opening using the same opening device and according to the same opening method.

[0019] A further technical solution is that the minimum distance between the center of the wall of each of the longitudinal holes close to the silver-plated copper flat strip and the outer ring of the silver-plated copper flat strip is set to A, and the minimum distance between the center of the wall of each of the longitudinal holes close to the silver-plated copper flat strip and the outer ring of the PTFE insulation layer is set to B, and A and B satisfy: A=B, so as to balance the requirements of cable weight and cable structural strength.

[0020] When A is larger (regardless of the specific size), the longitudinal hole is smaller. Although the cable structural strength increases, the weight also increases. When A is smaller, the longitudinal hole is larger. Although the cable weight decreases, its structural strength also decreases. When A=B, the cable structural strength is guaranteed and the cable weight is limited.

[0021] It should be added that the opening of longitudinal holes will affect the structural strength of the cable. This is a common influence and will not be explained in detail here.

[0022] According to a further technical solution, the minimum spacing between any two adjacent longitudinal holes is set to C, and C and A satisfy: C≥A, so as to ensure the strength near the edge of the PTFE insulation layer and further ensure the structural strength of the cable.

[0023] It should be added that if C is small, the two adjacent longitudinal holes are close to the wall of the silver-plated copper flat strip and are close to each other. At this time, the area occupied by the solid structure (or solid part) near the edge of the PTFE insulation layer is very small, while the area occupied by the longitudinal holes is very large, resulting in lower strength at the edge of the PTFE insulation layer.

[0024] According to a further technical solution, the silver-plated copper flat strip comprises a copper flat strip base, an oxygen-free copper intermediate layer and a silver-plated layer which are sequentially sleeved from the inside to the outside; The sum of the thickness of the oxygen-free copper intermediate layer and the silver-plated layer is ≥2.5 μm, and the thickness of the oxygen-free copper intermediate layer is in the range of 1-1.5 μm (or 1 μm-1.5 μm); The surface roughness of the silver-plated layer is ≤0.5 μm.

[0025] The sum of the thickness of the oxygen-free copper intermediate layer and the silver-plated layer is ≥2.5μm, ensuring the transmission requirements under the skin effect of electromagnetic waves below 10GHz.

[0026] The oxygen-free copper intermediate layer serves as an intermediate transition layer, and its thickness ranges from 1-1.5μm. It can fill the microscopic defects (such as pits and scratches) on the surface of the copper flat strip substrate without excessively increasing the overall thickness of the silver-plated copper flat strip, thereby helping to achieve a surface roughness of the silver-plated layer of ≤0.5μm.

[0027] The surface roughness of the silver plating layer is ≤0.5μm, which can reduce skin effect loss. Specifically, it can prevent transmission distortion when electromagnetic waves are transmitted along the surface of the conductor, thereby avoiding slight changes in the characteristic impedance and reducing the problem of increased VSWR (voltage standing wave ratio) or large third-order intermodulation (transmission distortion caused by nonlinear parasitic signals caused by uneven transmission) at high frequencies.

[0028] A further technical solution is that the PTFE insulation layer has a cross-shaped structure. Under this setting, the space occupied by each vertical hole is guaranteed, and the area occupied by the solid structure near the edge of the PTFE insulation layer is also guaranteed, balancing the requirements of cable weight and cable structural strength.

[0029] According to a further technical solution, the sheath layer is configured as a cross-linked ethylene tetrafluoroethylene sheath layer to ensure the temperature rating of the cable in this application, which is -65°C to +200°C.

[0030] If FEP or FPA materials are used, although they meet the 200°C temperature rating, they are not radiation-resistant. If silicone rubber is used, the temperature rating can be met, but it is not oil-resistant or radiation-resistant, and does not meet the requirements of high-tech fields such as aerospace.

[0031] The terms “first”, “second”, etc. used in this document do not specifically refer to an order or sequence, nor are they used to limit this case. They are only used to distinguish components or operations described with the same technical terms.

[0032] As used herein, “connected” or “positioned” may refer to two or more components or devices being in direct or indirect physical contact with each other, or may refer to two or more components or devices operating or moving with each other.

[0033] The terms “include”, “including”, “have”, etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] Unless otherwise noted, the terms used herein generally have their ordinary meanings in the art, in the context of this application, and in the specific context. Certain terms used to describe this application are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of this application.

[0035] The terms "front", "back", "up", "down", "left", "right", etc. used in this article are all directional terms. In this case, they are only used to illustrate the positional relationship between the various structures, and are not used to limit the protection plan of this case and the specific direction during actual implementation.

[0036] The working principle and advantages of the present invention are as follows: The PTFE insulation layer has insulating properties, and the attenuation constant remains almost unchanged at high temperatures, which ensures the temperature resistance level of the cable in this application and enables the cable in this application to meet the signal transmission requirements under high temperature conditions.

[0037] By opening vertical holes in the PTFE insulation layer, the weight of the insulation layer and thus the cable can be reduced, and the signal attenuation can be reduced by reducing dielectric loss.

[0038] Four vertical holes provide 360° mechanical support, ensuring the cable maintains structural stability under dynamic conditions such as bending and swaying. Compared to three-hole and five-hole structures, the four-hole structure minimizes degradation in attenuation, characteristic impedance, and return loss, ensuring effective signal transmission. In other words, the four-hole structure strikes a balance between mechanical support and transmission characteristics.

[0039] Compared to fan-shaped or semicircular holes, the crescent-shaped vertical holes create smaller gaps. While this increases the dielectric loss of the insulation layer, it also improves the mechanical support of the insulation layer, achieving a balance between dielectric loss and mechanical support. If a fan-shaped or semicircular hole is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edge, which can easily lead to mechanical support failure, insulation cracking, and ultimately distortion of the cable's overall characteristic impedance.

[0040] The longitudinal holes are evenly distributed in the circumferential direction of the PTFE insulation layer, so that the insulation layer is more evenly stressed and supported in the circumferential direction, reducing the risk of cracking or deformation of the insulation layer and extending the overall service life.

[0041] The core area of ​​the PTFE insulation layer (near the inner ring) is the key location for electric field, stress or dielectric transmission. Placing the longitudinal holes in the edge area of ​​the PTFE insulation layer near the outer ring can avoid damaging the material continuity of the core area and ensure that the insulation strength of the central part of the insulation layer is not affected by the holes.

[0042] By combining metal composite carbon fibers with high-heat-resistant resin, a highly conductive carbon fiber rod, or composite conductive rod, is produced. The composite conductive rod serves as the main body of the inner conductor. In the prior art, inner conductors typically use pure copper or copper-clad aluminum, which suffer from excessive attenuation, heavy weight, and waste of non-ferrous metal resources. The use of composite conductive rods avoids these problems. The inner conductor in this application is a metal fiber composite conductor made by wrapping a silver-plated copper flat strip around the outer surface of a highly conductive carbon fiber rod and sintering it. The conductor exhibits high conductivity, high tensile strength, and resistance to bending fatigue.

[0043] In existing technologies, tinned or silver-plated copper wire braids are often used instead of silver-plated copper tape. This can lead to signal leakage in the braided layer, which can easily generate electromagnetic interference. Some existing technologies use aluminum foil, which, while achieving 100% coverage, has low shielding efficiency and is not heat-resistant. The present application utilizes silver-plated copper tape, which avoids these issues.

[0044] In the prior art, corrugated copper tubes or smooth copper tubes are generally used as outer conductors. Although this can improve cable performance, the cost is very high and the copper density is high, resulting in a heavier cable. The present application avoids these problems by using a corrugated aluminum tape shielding layer as the outer conductor.

[0045] In this application, the inner conductor adopts a structure of silver-plated copper flat tape wrapped around a composite conductive rod. Compared with solid metal (such as copper-clad aluminum or copper-clad steel), the hardness is significantly reduced, which improves the flexibility of the cable. The outer conductor adopts a corrugated aluminum tape structure, which can improve the flexibility compared with the copper tube.

[0046] In summary, the cable in this application improves transmission efficiency by reducing signal attenuation, extends service life by improving temperature resistance, ensures cable flexibility through structural adjustments to the inner and outer conductors, and achieves energy conservation and environmental protection by reducing the use of rare metals. The cable in this application weighs only 50-60% of the same type of copper-clad aluminum physically foamed insulated coaxial cable, reducing weight while saving copper and lowering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is one of the structural diagrams of the cable according to the embodiment of the present invention; Figure 2 This is the second structural diagram of the cable according to the embodiment of the present invention.

[0048] In the above figures: 1. Composite conductive rod; 2. Silver-plated copper flat strip; 3. PTFE insulation layer; 31. Vertical hole; 4. Corrugated aluminum tape shielding layer; 5. Sheath layer. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments: Embodiment: The present invention will be clearly illustrated below with drawings and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0050] The terms used herein are for describing specific embodiments only and are not intended to be limiting of the present invention. Singular forms such as "a," "the," "this," "this," and "the" as used herein also include plural forms.

[0051] See also Figure 1-Figure 2 , an ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable, comprising a composite conductive rod 1, a silver-plated copper flat tape 2, a PTFE insulation layer 3, a corrugated aluminum tape shielding layer 4 and a sheath layer 5 which are sequentially sleeved from the inside to the outside; The PTFE insulating layer 3 is provided with four identical longitudinal holes 31, each of which penetrates the PTFE insulating layer 3 along the extension direction of the PTFE insulating layer 3; Each of the longitudinal holes 31 is crescent-shaped; The vertical holes 31 are distributed equidistantly in the circumferential direction of the PTFE insulating layer 3; Each of the vertical holes 31 is disposed on the edge region of the PTFE insulating layer 3 close to the outer ring.

[0052] The PTFE insulating layer 3 has insulating properties, and its attenuation constant remains almost unchanged at high temperatures, thereby ensuring the temperature resistance level of the cable in this embodiment and enabling the cable in this embodiment to meet the signal transmission requirements under high temperature conditions.

[0053] By opening the vertical holes 31 on the PTFE insulating layer 3, the weight of the insulating layer and thus the cable can be reduced, and the degree of signal attenuation can be reduced by reducing dielectric loss.

[0054] The four vertical holes 31 provide 360° mechanical support, ensuring the cable maintains structural stability under dynamic conditions such as bending and swaying. Tests have shown that after 500,000 bending tests, the four-hole structure can ensure minimal degradation in attenuation, characteristic impedance, return loss, and other performance characteristics, ensuring effective signal transmission. This means the four-hole structure achieves a balance between mechanical support and transmission characteristics. Tests have shown that the dielectric loss under the four-hole structure is approximately 0.7×10 -4 When using a three-hole structure, although the mechanical support strength is sufficient, the dielectric loss is 5% higher than that of a four-hole structure, resulting in higher attenuation; under a five-hole structure, although the dielectric loss is 6% lower than that of a four-hole structure, the mechanical support capacity is reduced, which easily leads to damage and breakage of the insulation layer.

[0055] The crescent shape of the vertical hole 31 reduces the gap compared to a fan-shaped or semicircular shape. While this increases the dielectric loss of the insulation layer, it also improves the mechanical support of the insulation layer, achieving a balance between dielectric loss and mechanical support. If a fan-shaped or semicircular shape is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edge, which can easily lead to mechanical support failure, insulation layer cracking, and ultimately distortion of the cable's overall characteristic impedance.

[0056] The longitudinal holes 31 are evenly spaced in the circumferential direction of the PTFE insulating layer 3 , so that the insulating layer is more evenly stressed and supported in the circumferential direction, thereby reducing the risk of cracking or deformation of the insulating layer and extending the overall service life.

[0057] The core area of ​​the PTFE insulation layer 3 (near the inner ring) is a key part for electric field, stress or dielectric transmission. The vertical holes 31 are arranged in the edge area of ​​the PTFE insulation layer 3 near the outer ring to avoid damage to the material continuity of the core area and ensure that the insulation strength of the central part of the insulation layer is not affected by the holes.

[0058] In some embodiments, the center angle of the arc length of the vertical hole 31 ranges from 93° to 97°.

[0059] In some embodiments, a highly conductive carbon fiber rod, namely composite conductive rod 1, is formed by combining metal-coated carbon fibers (to enhance conductivity) with a high-heat-resistant resin (such as polyimide). Composite conductive rod 1 serves as the main inner conductor. In existing technology, inner conductors typically use pure copper or copper-clad aluminum, which suffer from excessive attenuation, high weight, and waste of non-ferrous metal resources. Composite conductive rod 1 avoids these issues. In this embodiment, the inner conductor is formed by wrapping a silver-plated copper flat ribbon 2 around the outer surface of the highly conductive carbon fiber rod. After sintering, the resulting metal fiber composite conductor exhibits high conductivity, high tensile strength, and resistance to bending fatigue.

[0060] Optionally, for composite conductive rod 1, the carbon content is 95%, the nitrogen content is 2.8%, the oxygen content is 2.2%, the surface roughness Ra is ≤ 15 nm, the density is 1.81 g / cm³, and the porosity is < 1%. For silver-plated copper flat strip 2, the copper strip thickness is 0.25-0.3 mm, the silver plating thickness is 2.5 μm, and the surface roughness is ≤ 0.5 μm.

[0061] In existing technologies, tinned or silver-plated copper wire braids are often used instead of silver-plated copper flat tape. This can lead to signal leakage in the braided layer, which can easily generate electromagnetic interference. Some existing technologies use aluminum foil, which can achieve 100% coverage but has low shielding efficiency and is not heat-resistant.

[0062] In the prior art, corrugated copper tubes or smooth copper tubes are generally used as outer conductors. While this can improve cable performance, it is very expensive and the high copper density results in a heavier cable. This embodiment, however, avoids these problems by using a corrugated aluminum tape shielding layer 4 as the outer conductor. Alternatively, the corrugated aluminum tape outer conductor shielding layer can be formed by longitudinally wrapping the aluminum tape through a welding process and then shaping it with a roller.

[0063] It should be added that the inner conductor adopts a structure in which a silver-plated copper flat strip 2 is wrapped around a composite conductive rod 1. Compared with the use of solid metal (such as copper-clad aluminum or copper-clad steel), the hardness is significantly reduced, thereby improving the flexibility of the cable. The outer conductor adopts a corrugated aluminum strip structure, which can improve the flexibility compared with the use of a copper tube.

[0064] In summary, the cable in this embodiment improves transmission efficiency by reducing signal attenuation, extends service life by improving heat resistance, ensures cable flexibility through structural adjustments to the inner and outer conductors, and achieves energy conservation and environmental protection by reducing the use of rare metals. The cable in this embodiment weighs only 50-60% of a similar copper-clad aluminum physically foamed insulated coaxial cable, reducing weight while also saving copper.

[0065] See also Figure 1 In this embodiment, the PTFE insulation layer 3 and the corrugated aluminum tape shielding layer 4 enclose each longitudinal hole 31. With this arrangement, in the radial direction of the cable, portions of the corrugated aluminum tape shielding layer 4 form the walls of each longitudinal hole 31. Compared to forming each longitudinal hole 31 by enclosing the PTFE insulation layer 3 itself, this arrangement simplifies the difficulty of creating each longitudinal hole 31, especially when the holes 31 must be continuously adjusted during the creation process to meet the desired shape.

[0066] See also Figure 1 In this embodiment, each of the longitudinal holes 31 is a centrally symmetrical structure, which reduces the difficulty of opening each longitudinal hole 31 and facilitates the use of the same opening device and the same opening method.

[0067] See also Figure 2 In this embodiment, the minimum distance between the center of the wall of each of the longitudinal holes 31 close to the silver-plated copper flat strip 2 and the outer circle of the silver-plated copper flat strip 2 is set to A, and the minimum distance between the center of the wall of each of the longitudinal holes 31 close to the silver-plated copper flat strip 2 and the outer circle of the PTFE insulation layer 3 is set to B. A and B satisfy: A=B, so as to balance the requirements of cable weight and cable structural strength.

[0068] When A is larger (regardless of the specific size), the longitudinal hole 31 is smaller. Although the cable structural strength increases, the weight also increases. When A is smaller, the longitudinal hole 31 is larger. Although the cable weight decreases, its structural strength also decreases. When A=B, the cable structural strength is guaranteed and the cable weight is limited.

[0069] It should be added that the provision of the longitudinal hole 31 will affect the strength of the cable structure, which is a conventional influence and will not be elaborated here.

[0070] See also Figure 2 In this embodiment, the minimum spacing between any two adjacent longitudinal holes 31 is set to C, and C and A satisfy: C≥A, so as to ensure the strength near the edge of the PTFE insulation layer 3, and thus ensure the strength of the cable structure.

[0071] It should be added that if C is small, the two adjacent longitudinal holes 31 are close to the wall of the silver-plated copper flat strip 2 and are almost in contact with each other. At this time, the area occupied by the solid structure (or the solid part) near the edge of the PTFE insulating layer 3 is very small, while the area occupied by the longitudinal holes 31 is very large, resulting in lower strength at the edge of the PTFE insulating layer 3.

[0072] In this embodiment, the silver-plated copper flat strip 2 includes a copper flat strip base (not shown in the figure), an oxygen-free copper intermediate layer (not shown in the figure), and a silver-plated layer (not shown in the figure) which are sequentially sleeved from the inside to the outside. The sum of the thickness of the oxygen-free copper intermediate layer and the silver-plated layer is ≥2.5 μm, and the thickness of the oxygen-free copper intermediate layer is in the range of 1-1.5 μm (or 1 μm-1.5 μm); The surface roughness of the silver-plated layer is ≤0.5 μm.

[0073] According to the skin depth formula: , δ is the skin depth, ω is the angular frequency, μ is the magnetic permeability, and the symbol on the μ side is the conductivity. The skin depth of electromagnetic waves when they are transmitted inside the silver-plated layer at different frequencies is as follows:

[0074] The sum of the thickness of the oxygen-free copper intermediate layer and the silver-plated layer is ≥2.5μm, ensuring the transmission requirements under the skin effect of electromagnetic waves below 10GHz.

[0075] The oxygen-free copper intermediate layer serves as an intermediate transition layer, and its thickness ranges from 1 to 1.5 μm. It can fill microscopic defects (such as pits and scratches) on the surface of the copper flat strip substrate without excessively increasing the overall thickness of the silver-plated copper flat strip 2, thereby helping to achieve a surface roughness of the silver-plated layer of ≤0.5 μm.

[0076] The surface roughness of the silver plating layer is ≤0.5μm, which can reduce skin effect loss. Specifically, it can prevent transmission distortion when electromagnetic waves are transmitted along the surface of the conductor, thereby avoiding slight changes in the characteristic impedance and reducing the problem of increased VSWR (voltage standing wave ratio) or large third-order intermodulation (transmission distortion caused by nonlinear parasitic signals caused by uneven transmission) at high frequencies.

[0077] See also Figure 1 In this embodiment, the PTFE insulating layer 3 is a cross-shaped structure. Under this setting, the space occupied by each vertical hole 31 is guaranteed, and the area occupied by the solid structure near the edge of the PTFE insulating layer 3 is also guaranteed, balancing the requirements of cable weight and cable structural strength.

[0078] In this embodiment, the sheath layer 5 is configured as a cross-linked ethylene tetrafluoroethylene sheath layer to ensure the temperature rating of the cable in this embodiment, which is -65°C to +200°C.

[0079] If FEP or FPA materials are used, although they meet the 200°C temperature rating, they are not radiation-resistant. If silicone rubber is used, the temperature rating can be met, but it is not oil-resistant or radiation-resistant, and does not meet the requirements of high-tech fields such as aerospace.

[0080] This embodiment significantly reduces the signal attenuation amplitude through the above settings, as shown in the figure below:

[0081] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. An ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable, characterized by: It comprises a composite conductive rod (1), a silver-plated copper flat strip (2), a PTFE insulating layer (3), a corrugated aluminum tape shielding layer (4) and a sheath layer (5) which are sequentially sleeved from the inside to the outside; The PTFE insulating layer (3) is provided with four identical longitudinal holes (31), each of the longitudinal holes (31) passing through the PTFE insulating layer (3) along the extension direction of the PTFE insulating layer (3); Each of the longitudinal holes (31) is crescent-shaped; The longitudinal holes (31) are distributed equidistantly in the circumferential direction of the PTFE insulating layer (3); Each of the longitudinal holes (31) is arranged on the edge area of ​​the PTFE insulating layer (3) close to the outer ring.

2. The ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to claim 1, characterized in that: The PTFE insulating layer (3) and the corrugated aluminum tape shielding layer (4) enclose each of the longitudinal holes (31).

3. The ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to claim 2, characterized in that: Each of the longitudinal holes (31) is a centrosymmetrical structure.

4. The ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to claim 3, characterized in that: The minimum distance between the center of the wall of each of the longitudinal holes (31) close to the silver-plated copper flat strip (2) and the outer ring of the silver-plated copper flat strip (2) is set to A, and the minimum distance between the center of the wall of each of the longitudinal holes (31) close to the silver-plated copper flat strip (2) and the outer ring of the PTFE insulating layer (3) is set to B, and A and B satisfy: A=B.

5. The ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to claim 4, characterized in that: The minimum spacing between any two adjacent longitudinal holes (31) is set to C, and C and A satisfy: C≥A.

6. An ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to any one of claims 1 to 5, characterized in that: The silver-plated copper flat strip (2) comprises a copper flat strip base, an oxygen-free copper middle layer and a silver-plated layer which are sequentially sleeved from the inside to the outside; The sum of the thickness of the oxygen-free copper intermediate layer and the silver-plated layer is ≥2.5 μm, and the thickness of the oxygen-free copper intermediate layer is in the range of 1 μm to 1.5 μm; The surface roughness of the silver-plated layer is ≤0.5 μm.

7. An ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to any one of claims 1 to 5, characterized in that: The PTFE insulating layer (3) is a cross-shaped structure.

8. An ultra-high frequency low-loss longitudinal hole PTFE insulated coaxial cable according to any one of claims 1 to 5, characterized in that: The sheath layer (5) is configured as a cross-linked ethylene tetrafluoroethylene sheath layer.

Images