Ultrahigh frequency low-loss longitudinal hole PTFE insulated coaxial cable

Abstract

The utility model relates to cable technical field, concretely relates to a kind of ultrahigh frequency low-loss longitudinal hole PTFE insulation coaxial cable, composite conductive bar, silver-plated copper flat strip, PTFE insulation layer, corrugated aluminium strip shielding layer and sheath layer are sequentially sleeved from inside to outside;Four same longitudinal holes are equipped on the PTFE insulation layer, each longitudinal hole penetrates the PTFE insulation layer along the extension direction of the PTFE insulation layer;Each longitudinal hole is crescent shape;Each longitudinal hole is equidistantly distributed in the circumferential direction of the PTFE insulation layer;Each longitudinal hole is arranged on the edge area of the PTFE insulation layer close to outer ring.The cable in the application reduces signal attenuation to improve transmission efficiency, and improves temperature resistance grade to prolong service life, and adjusts the structure of inner conductor and outer conductor to ensure that the cable has certain flexibility, and reduces the use amount of rare metal to realize energy saving and environmental protection.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, specifically to an ultra-high frequency, low-loss, longitudinally perforated PTFE insulated coaxial cable. Background Technology

[0002] Traditional high-frequency coaxial cables mostly use foamed polyethylene as the insulation layer. Its advantages include lower cost and a smaller dielectric loss factor (approximately 1×10⁻⁶) after foaming. -4 -1.5×10 -4 However, the cutoff frequency of this type of cable is usually below 6GHz. In high-frequency scenarios, especially millimeter-wave scenarios of 10GHz and above, and ultra-high-frequency scenarios such as aerospace and military defense, the dielectric loss increases significantly, resulting in severe signal attenuation. In addition, its temperature resistance is only -40 to +80℃, which is difficult to meet the needs of use in complex environments. Currently, there are still coaxial cables that use FEP as insulation, with a dielectric loss factor of approximately 2 × 10⁻⁶. -4 After foaming, its dielectric loss factor is slightly lower than that of foamed polyethylene; however, as the frequency increases, its dielectric loss factor increases rapidly and may even exceed that of foamed polyethylene, thus failing to meet the requirements of high-frequency communication applications. Furthermore, its temperature resistance is approximately -40 to +125°C, a characteristic that limits its application in high-end fields such as aerospace where high temperature resistance is required. To address the aforementioned issues, one approach is to use PTFE as the insulation layer. While this improvement enhances the temperature resistance, it presents several drawbacks: firstly, the solid structure results in a heavier cable, hindering cost control; secondly, the dielectric loss factor is similar to that of foamed polyethylene, indicating room for further optimization. These two issues limit the cable's application in scenarios with stringent requirements regarding weight, cost, and dielectric loss.

[0003] Therefore, how to overcome the shortcomings of the existing technology mentioned above has become the subject of this utility model. Utility Model Content

[0004] The purpose of this invention is to provide an ultra-high frequency, low-loss, longitudinally perforated PTFE insulated coaxial cable.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A high-frequency, low-loss longitudinally perforated PTFE-insulated coaxial cable includes a composite conductive rod, a silver-plated copper flat strip, a PTFE insulation layer, a corrugated aluminum tape shielding layer, and a sheath layer, which are sequentially connected from the inside to the outside. The PTFE insulation layer has four identical longitudinal holes, and each of the longitudinal holes penetrates the PTFE insulation layer along the extending direction of the PTFE insulation layer. All of the longitudinal holes are crescent-shaped; Each of the longitudinal holes is equidistantly distributed in the circumferential direction of the PTFE insulation layer; Each of the longitudinal holes is located on the edge region of the PTFE insulation layer near the outer ring.

[0006] The PTFE insulation layer has insulating properties, and its attenuation constant remains almost unchanged at high temperatures, ensuring the temperature resistance rating 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 creating longitudinal holes in the PTFE insulation layer, the weight of the insulation layer can be reduced, thereby reducing the weight of the cable. Signal attenuation can also be reduced by decreasing dielectric loss.

[0008] Four longitudinal holes provide 360° mechanical support, ensuring structural stability of the cable under dynamic conditions such as bending and swaying. Tests have shown that after 500,000 bending cycles, the four-hole structure maintains minimal degradation in attenuation, characteristic impedance, and return loss, ensuring effective signal transmission. In other words, the four-hole structure achieves a balance between mechanical support and transmission characteristics. Tests have also shown that the dielectric loss with the four-hole structure is approximately 0.7 × 10⁻⁶. -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. With 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 can easily lead to damage and breakage of the insulation layer.

[0009] The crescent-shaped longitudinal holes, compared to fan-shaped or semi-circular ones, result in smaller gaps. While this increases the dielectric loss of the insulation layer, it also improves its mechanical support capability, achieving a balance between the two. If a fan-shaped or semi-circular design is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edges. This can easily lead to mechanical support failure, insulation layer cracking, and ultimately distortion of the overall characteristic impedance of the cable.

[0010] The longitudinal holes are evenly distributed along the circumference of the PTFE insulation layer, making the stress and support of the insulation layer more uniform 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 (near the inner ring) of the PTFE insulation layer is the key part for the transmission of electric field, stress or medium. By placing the longitudinal holes on the edge area of ​​the PTFE insulation layer near the outer ring, the continuity of the material in the core area can be avoided, and the insulation strength of the central part of the insulation layer can be guaranteed not to be affected by the holes.

[0012] In some embodiments, metal-composite carbon fibers (to improve conductivity) are combined with high-heat-resistant resins (such as polyimide) to form highly conductive carbon fiber rods, i.e., composite conductive rods, which serve as the main body of the inner conductor. In the prior art, the inner conductor is generally made of pure copper or copper-clad aluminum, which suffers from problems such as excessive final attenuation, heavy weight, and waste of non-ferrous metal resources. Using composite conductive rods avoids these problems. In this embodiment, the inner conductor is formed by winding silver-plated copper flat strips around the outer surface of the highly conductive carbon fiber rod, and then sintering it to form a metal fiber composite conductor, which has the characteristics of high conductivity, high tensile strength, and resistance to bending fatigue.

[0013] In existing technologies, tin-plated or silver-plated copper wire braided structures are generally used instead of silver-plated copper flat strips. This leads to signal leakage in the braided layer, which can easily generate electromagnetic interference. Some existing technologies use aluminum foil layers, which can achieve 100% coverage, but the shielding efficiency is not high and it is not resistant to high temperatures.

[0014] In existing technologies, corrugated copper tubes or smooth copper tubes are generally used as outer conductors. Although this can improve cable performance, the cost is high, and the high density of copper makes the cable heavy. This embodiment avoids these problems by using a corrugated aluminum tape shielding layer as the outer conductor. Optionally, the aluminum tape is longitudinally wrapped through a welding process, and after being shaped by a pressure roller, a corrugated aluminum tape outer conductor shielding layer is formed.

[0015] It should be added that the inner conductor adopts a structure of silver-plated copper flat strip wound with composite conductive rod, which significantly reduces the hardness compared to using solid metal (such as copper-clad aluminum or copper-clad steel), thus improving the flexibility of the cable. The outer conductor adopts a corrugated aluminum strip structure, which can improve flexibility compared to using copper tube.

[0016] In summary, the cable in this embodiment improves transmission efficiency by reducing signal attenuation, extends service life by increasing 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, saving copper material while reducing weight.

[0017] A further technical solution involves the PTFE insulation layer and the corrugated aluminum tape shielding layer enclosing and forming each of the longitudinal holes. In this configuration, a portion of the corrugated aluminum tape shielding layer forms the wall of each longitudinal hole in the radial direction of the cable. Compared to forming each longitudinal hole by the PTFE insulation layer itself, this configuration reduces the difficulty of creating each longitudinal hole, especially when continuous adjustments are needed during the creation of each longitudinal hole to achieve a predetermined shape.

[0018] A further technical solution is that each of the longitudinal holes is a centrally symmetrical structure, which reduces the difficulty of opening each longitudinal hole and makes it easier to use the same opening device and follow the same opening method.

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

[0020] When A is large (regardless of specific dimensions), the longitudinal hole is small, which increases the cable's structural strength but also its weight; when A is small, the longitudinal hole is large, which reduces the cable's weight but also its structural strength; when A=B, the cable's structural strength is guaranteed, but its weight is limited.

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

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

[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. In this case, the solid structure (or solid part) near the edge of the PTFE insulation layer occupies a very small area, while the longitudinal holes occupy a very large area, resulting in lower strength at the edge of the PTFE insulation layer.

[0024] A further technical solution is that the silver-plated copper flat strip includes a copper flat strip substrate, an oxygen-free copper intermediate layer and a silver plating layer sequentially nested from the inside to the outside. The sum of the thicknesses of the oxygen-free copper intermediate layer and the silver plating layer is ≥2.5μm, and the thickness of the oxygen-free copper intermediate layer is in the range of 1-1.5μm (or 1μm-1.5μm). The surface roughness of the silver plating layer is ≤0.5μm.

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

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

[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 propagate along the conductor surface, thereby avoiding slight changes in characteristic impedance and reducing the problems of increased VSWR (voltage standing wave ratio) or excessive third-order intermodulation (transmission distortion caused by nonlinear parasitic signals caused by uneven transmission) at high frequencies.

[0028] In a further technical solution, the PTFE insulation layer has a cross-shaped structure. This design ensures the space occupied by each longitudinal hole and the area occupied by the solid structure near the edge of the PTFE insulation layer, thus balancing the requirements for cable weight and cable structural strength.

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

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

[0031] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0032] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

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

[0034] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.

[0035] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0036] The working principle and advantages of this utility model are as follows: The PTFE insulation layer has insulating properties and its attenuation constant remains almost unchanged at high temperatures, ensuring the temperature resistance rating of the cable in this application and enabling the cable in this application to meet the signal transmission requirements under high temperature conditions.

[0037] By creating longitudinal holes in the PTFE insulation layer, the weight of the insulation layer can be reduced, thereby reducing the weight of the cable. Signal attenuation can also be reduced by decreasing dielectric loss.

[0038] With four longitudinal holes, 360° mechanical support is achieved, ensuring structural stability of the cable under dynamic conditions such as bending and swaying. Compared to 3-hole and 5-hole structures, the 4-hole structure ensures a smaller decrease in performance such as attenuation, characteristic impedance, and return loss, guaranteeing signal transmission effectiveness. In other words, the 4-hole structure achieves a balance between mechanical support and transmission characteristics.

[0039] The crescent-shaped longitudinal holes, compared to fan-shaped or semi-circular ones, result in smaller gaps. While this increases the dielectric loss of the insulation layer, it also improves its mechanical support capability, achieving a balance between the two. If a fan-shaped or semi-circular design is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edges. This can easily lead to mechanical support failure, insulation layer cracking, and ultimately distortion of the overall characteristic impedance of the cable.

[0040] The longitudinal holes are evenly distributed along the circumference of the PTFE insulation layer, making the stress and support of the insulation layer more uniform 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 (near the inner ring) of the PTFE insulation layer is the key part for the transmission of electric field, stress or medium. By placing the longitudinal holes on the edge area of ​​the PTFE insulation layer near the outer ring, the continuity of the material in the core area can be avoided, and the insulation strength of the central part of the insulation layer can be guaranteed not to be affected by the holes.

[0042] Highly conductive carbon fiber rods, or composite conductive rods, are produced by combining metal-coated carbon fibers with high-heat-resistant resin. These composite conductive rods form the main body of the inner conductor. In existing technologies, the inner conductor is generally made of pure copper or copper-clad aluminum, which suffers from problems such as excessive final attenuation, heavy weight, and waste of non-ferrous metal resources. Using composite conductive rods avoids these problems. In this application, the inner conductor is formed by winding silver-plated copper flat strips around the outer surface of the highly conductive carbon fiber rod, followed by sintering to create a metal fiber composite conductor, exhibiting high conductivity, high tensile strength, and resistance to bending fatigue.

[0043] In existing technologies, tin-plated or silver-plated copper wire braided structures are generally used instead of silver-plated copper flat strips. This leads to signal leakage in the braided layer, which can easily generate electromagnetic interference. Some existing technologies use aluminum foil layers, which can achieve 100% coverage, but the shielding efficiency is not high and it is not resistant to high temperatures. This application avoids these problems by using silver-plated copper flat strips.

[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 high and the high density of copper makes the cable heavy. However, this 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 strip wound with composite conductive rod, which significantly reduces the hardness compared to using solid metal (such as copper-clad aluminum or copper-clad steel) and improves the flexibility of the cable. The outer conductor adopts a corrugated aluminum strip structure, which improves the flexibility compared to using copper tube.

[0046] In summary, the cable of 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 of this application weighs only 50-60% of a similar copper-clad aluminum physically foamed insulated coaxial cable, reducing weight while saving copper usage and lowering costs. Attached Figure Description

[0047] Figure 1 This is one of the structural schematic diagrams of the cable according to an embodiment of the present utility model; Figure 2 This is the second schematic diagram of the cable structure in an embodiment of this utility model.

[0048] In the above attached diagram: 1. Composite conductive rod; 2. Silver-plated copper flat strip; 3. PTFE insulation layer; 31. Longitudinal hole; 4. Corrugated aluminum strip shielding layer; 5. Sheath layer. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0050] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0051] See Figures 1-2 A high-frequency, low-loss longitudinal hole PTFE insulated coaxial cable includes a composite conductive rod 1, a silver-plated copper flat strip 2, a PTFE insulation layer 3, a corrugated aluminum strip shielding layer 4, and a sheath layer 5, which are sequentially connected from the inside to the outside. The PTFE insulation layer 3 has four identical longitudinal holes 31, and each longitudinal hole 31 penetrates the PTFE insulation layer 3 along the extending direction of the PTFE insulation layer 3. Each of the longitudinal holes 31 is crescent-shaped; The longitudinal holes 31 are equidistantly distributed in the circumferential direction of the PTFE insulation layer 3; Each of the longitudinal holes 31 is provided on the edge region of the PTFE insulating layer 3 near the outer ring.

[0052] The PTFE insulation layer 3 has insulating properties and its attenuation constant remains almost unchanged at high temperatures, ensuring the temperature resistance rating 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 creating longitudinal holes 31 in the PTFE insulation layer 3, the weight of the insulation layer can be reduced, thereby reducing the weight of the cable. Furthermore, the signal attenuation can be reduced by decreasing dielectric loss.

[0054] Four longitudinal holes (31) provide 360° mechanical support, ensuring structural stability of the cable under dynamic conditions such as bending and swaying. Tests have shown that after 500,000 bending cycles, the four-hole structure maintains minimal degradation in attenuation, characteristic impedance, and return loss, ensuring effective signal transmission. In other words, the four-hole structure achieves a balance between mechanical support and transmission characteristics. Tests have also shown that the dielectric loss under the four-hole structure is approximately 0.7 × 10⁻⁶. -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. With 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 can easily lead to damage and breakage of the insulation layer.

[0055] The longitudinal hole 31 is crescent-shaped, which, compared to a fan-shaped or semi-circular shape, results in a smaller gap. While this increases the dielectric loss of the insulation layer, it also improves its mechanical support capability, achieving a balance between the two. If a fan-shaped or semi-circular design is used, the insulation layer will bend, resulting in a smaller insulation thickness at the edges, which can easily lead to mechanical support failure, insulation layer cracking, and ultimately distortion of the overall characteristic impedance of the cable.

[0056] The longitudinal holes 31 are evenly distributed in the circumferential direction of the PTFE insulation layer 3, which makes the stress and support of the insulation layer in the circumferential direction more uniform, reduces the risk of cracking or deformation of the insulation layer, and extends the overall service life.

[0057] The core area (near the inner ring) of the PTFE insulation layer 3 is a critical part for the transmission of electric field, stress or medium. By setting each longitudinal hole 31 on the edge area of ​​the PTFE insulation layer 3 near the outer ring, the continuity of the material in the core area can be avoided, and the insulation strength of the central part of the insulation layer can be guaranteed to be unaffected by the holes.

[0058] In some embodiments, the arc length of the longitudinal hole 31 has a central angle range of 93-97°.

[0059] In some embodiments, metal-composite carbon fibers (to improve conductivity) are combined with high-heat-resistant resins (such as polyimide) to form high-conductivity carbon fiber rods, namely composite conductive rods 1, which serve as the main body of the inner conductor. In the prior art, the inner conductor is generally made of pure copper or copper-clad aluminum, which suffers from problems such as excessive final attenuation, heavy weight, and waste of non-ferrous metal resources. Using composite conductive rods 1 avoids these problems. In this embodiment, the inner conductor is formed by winding silver-plated copper flat strips 2 around the outer surface of the high-conductivity carbon fiber rod, and then sintering it to form a metal fiber composite conductor, which has the characteristics of high conductivity, high tensile strength, and resistance to bending fatigue.

[0060] Optionally, for the 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 ≤15nm, the density is 1.81g / cm³, and the porosity is <1%. For the silver-plated copper flat strip 2, the copper strip thickness is 0.25-0.3mm, the silver plating thickness is 2.5μm, and the surface roughness is ≤0.5μm.

[0061] In existing technologies, tin-plated or silver-plated copper wire braided structures are generally used instead of silver-plated copper flat strips, which leads to signal leakage in the braided layer and easy generation of electromagnetic interference. Some existing technologies use aluminum foil layers, which can achieve 100% coverage, but the shielding efficiency is not high and it is not resistant to high temperatures.

[0062] In existing technologies, corrugated copper tubes or smooth copper tubes are generally used as outer conductors. Although this can improve cable performance, the cost is high, and the high density of copper makes the cable heavy. However, this embodiment avoids these problems by using a corrugated aluminum tape shielding layer 4 as the outer conductor. Optionally, the aluminum tape is longitudinally wrapped through a welding process, and after being shaped by a pressure roller, a corrugated aluminum tape outer conductor shielding layer is formed.

[0063] It should be added that the inner conductor adopts a structure of silver-plated copper flat strip 2 wound with 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, which improves the flexibility of the cable. The outer conductor adopts a corrugated aluminum strip structure, which can improve the flexibility compared with the use of copper tube.

[0064] In summary, the cable in this embodiment improves transmission efficiency by reducing signal attenuation, extends service life by increasing 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, saving copper material while reducing weight.

[0065] See Figure 1 In this embodiment, the PTFE insulation layer 3 and the corrugated aluminum tape shielding layer 4 enclose each of the longitudinal holes 31. With this configuration, a portion of the corrugated aluminum tape shielding layer 4 forms the wall of each longitudinal hole 31 in the radial direction of the cable. Compared to having the PTFE insulation layer 3 itself enclose each longitudinal hole 31, this configuration reduces the difficulty of creating each longitudinal hole 31, especially when it is necessary to continuously adjust it during the creation process to meet a predetermined shape.

[0066] See 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 makes it easier to use the same opening device and follow the same opening method.

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

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

[0069] It should be added that the opening of the longitudinal hole 31 will affect the strength of the cable structure. This is a normal effect and will not be explained in detail here.

[0070] See Figure 2 In this embodiment, the minimum distance between any two adjacent longitudinal holes 31 is set as C, and C and A satisfy: C≥A, so as to ensure the strength near the edge of the PTFE insulation layer 3, thereby ensuring 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. At this time, the solid structure (or solid part) near the edge of the PTFE insulation layer 3 occupies a small area, while the longitudinal hole 31 occupies a large area, resulting in lower strength at the edge of the PTFE insulation layer 3.

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

[0073] According to the skin depth formula: , δ represents the skin depth, ω represents the angular frequency, and μ represents the permeability. The sign on the permeability side indicates conductivity. The skin depth of electromagnetic waves propagating inside the silver plating layer at different frequencies is as follows:

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

[0075] The oxygen-free copper intermediate layer serves as an intermediate transition layer, with a thickness ranging from 1 to 1.5 μm. 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 2, thus helping to achieve a surface roughness of ≤0.5 μm for the silver plating layer.

[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 propagate along the conductor surface, thereby avoiding slight changes in characteristic impedance and reducing the problems of increased VSWR (voltage standing wave ratio) or excessive third-order intermodulation (transmission distortion caused by nonlinear parasitic signals caused by uneven transmission) at high frequencies.

[0077] See Figure 1 In this embodiment, the PTFE insulation layer 3 has a cross-shaped structure. With this arrangement, the space occupied by each longitudinal hole 31 is guaranteed, and the area occupied by the solid structure near the edge of the PTFE insulation layer 3 is also guaranteed, thus balancing the requirements for cable weight and cable structural strength.

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

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

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

[0081] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A high-frequency, low-loss, longitudinally perforated PTFE-insulated coaxial cable, characterized in that: It includes a composite conductive rod (1), a silver-plated copper flat strip (2), a PTFE insulation layer (3), a corrugated aluminum strip shielding layer (4), and a sheath layer (5) that are sequentially connected from the inside to the outside. The PTFE insulation layer (3) has four identical longitudinal holes (31), and each longitudinal hole (31) penetrates the PTFE insulation layer (3) along the extension direction of the PTFE insulation layer (3). Each of the longitudinal holes (31) is crescent-shaped; Each of the longitudinal holes (31) is equidistantly distributed in the circumferential direction of the PTFE insulation layer (3); Each of the longitudinal holes (31) is located on the edge region of the PTFE insulation layer (3) near the outer ring.

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

3. The ultra-high frequency, low-loss, longitudinally perforated PTFE insulated coaxial cable according to claim 2, characterized in that: All of the longitudinal holes (31) are centrally symmetrical structures.

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 longitudinal hole (31) near the silver-plated copper flat strip (2) and the outer ring of the silver-plated copper flat strip (2) is set as A, and the minimum distance between the center of the wall of each longitudinal hole (31) near the silver-plated copper flat strip (2) and the outer ring of the PTFE insulation layer (3) is set as B. A and B satisfy: A=B.

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

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

7. A high-frequency, low-loss, longitudinally perforated PTFE-insulated coaxial cable according to any one of claims 1-5, characterized in that: The PTFE insulation layer (3) has a cross-shaped structure.

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

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