A low-loss and low-standing-wave ultra-cutoff frequency radio frequency coaxial cable

Abstract

This application belongs to the field of wireless communication technologies, and particularly relates to a low-loss, low-standing-wave, and ultra-cutoff-frequency radio frequency coaxial cable. The outer conductor of the cable is an annular corrugated tube with a corrugated structure. On one surface of the corrugated structure facing the insulating layer, tooth peaks and tooth grooves are alternately arranged along the axial direction. The tooth peaks have inverted V-shaped peak tips for sinking into the foamed insulating layer, and the tooth grooves have arc-shaped groove bottoms for accommodating the foamed insulating layer. This structure is particularly obvious in improving the TE electromagnetic waves exceeding the cutoff frequency, enabling this radio frequency coaxial cable to have the capabilities of low loss, low standing wave, and working at ultra-cutoff frequencies. It can provide a relatively wide operating frequency under large-size conditions, meeting the requirements of low loss, low standing wave, and high frequency during mobile communication network formation. The standing-wave diagram shows that the interference peaks at 3.3 GHz - 3.7 GHz of the cable disappear, indicating that the cable can continue to work after the ultra-cutoff frequency, broadening the operating frequency of the original cable and further meeting the requirements of the 5G operating frequency band.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technologies, and more specifically, relates to a low-loss, low-standing-wave, ultra-cutoff-frequency radio frequency coaxial cable. Background Art

[0002] Radio frequency coaxial cables are a type of transmission medium widely used in antenna systems and are an important part of connecting transmitters, receivers, and antennas. Traditional radio frequency coaxial cables are mainly used for signal transmission. In an antenna system, the design and characteristics of the cable have an important impact on the overall performance.

[0003] With the rapid development of antenna technologies, the demand for high-frequency bands is increasing day by day. However, limited by the cut-off operating frequency of coaxial cables, after the cable exceeds a certain size, affected by higher harmonics, the standing wave and transmission loss performance of the coaxial cable deteriorate severely after exceeding the cut-off frequency, resulting in it no longer being usable after exceeding the cut-off frequency; for example, traditional inch coaxial cables, whose cut-off frequency is about 2.7 GHz, still cannot meet the operating frequency of current mobile communication 5G. As a result, when forming a mobile communication network, one often has to choose coaxial cables with a smaller size that can support higher frequencies. However, the transmission loss of coaxial cables with a smaller size is often greater than that of coaxial cables with a larger size, easily causing signal power waste, greatly reducing the coverage range of mobile communication devices, and increasing the network construction cost. Summary of the Invention

[0004] In view of the deficiencies or improvement requirements of the prior art, this application provides a low-loss, low-standing-wave, ultra-cutoff-frequency radio frequency coaxial cable. This coaxial cable can provide a relatively wide operating frequency under large-size conditions, meeting the requirements of low loss, low standing wave, and high frequency when forming a mobile communication network.

[0005] A low-loss, low-standing-wave, ultra-cutoff-frequency radio frequency coaxial cable provided by this application includes, from the inside to the outside in sequence, an inner conductor, a foamed insulation layer, an outer conductor, and a sheath layer, where:

[0006] The outer conductor is an annular corrugated tube with a corrugated structure. On one side surface of the corrugated structure facing the foamed insulation layer, tooth peaks and tooth grooves are alternately arranged along the axial direction. The tooth peaks have inverted V-shaped peak tips for sinking into the foamed insulation layer, and the tooth grooves have arc-shaped groove bottoms for accommodating the foamed insulation layer.

[0007] Through the above technical solution conceived by this application, compared with the prior art, by specifically designing the corrugated structure of the outer conductor, after the outer conductor is tightly coated on the outer periphery of the foamed insulation layer, the inverted V-shaped peaks in the outer conductor can sink into the foamed insulation layer to form physical occlusion, preventing relative sliding or separation between the outer conductor and the foamed insulation layer, and the tooth grooves in the shape of an arc-shaped groove bottom can accommodate the foamed insulation layer, weakening the generation of gaps (especially radial gaps). This is beneficial to reducing the reflection generated when the electromagnetic signal flowing from the inner conductor to the outer conductor passes through different cut-off layers, improving the voltage standing wave ratio and transmission loss performance, especially for the improvement of TE electromagnetic waves exceeding the cut-off frequency is particularly obvious, enabling this radio frequency coaxial cable to have the ability of low loss, low standing wave and operating at frequencies above the cut-off frequency, and can provide a relatively wide operating frequency under large specification conditions, meeting the requirements of low loss, low standing wave and high frequency in mobile communication networking.

[0008] As a further preference, the corrugation depth of the outer conductor satisfies the following relational expression:

[0009]

[0010]

[0011] Wherein, represents the corrugation depth, represents the radius of the arc of the arc-shaped groove bottom, represents the corrugation pitch of the outer conductor, represents the angle between the surface of the tooth groove and the axis of the outer conductor.

[0012] As a further preference, the corrugation pitch of the outer conductor is 2 mm - 4 mm.

[0013] As a further preference, the radial gap between the outer conductor and the foamed insulation layer is less than 1 mm.

[0014] As a further preference, the radial gap between the outer conductor and the foamed insulation layer is 0.2 mm - 0.8 mm.

[0015] As a further preference, the compression ratio of the outer conductor is 1.005 - 1.05.

[0016] As a further preference, the outer conductor is obtained by the following method:

[0017] The smooth strip of the outer conductor is corrugated with a preset corrugated shape to obtain a corrugated conductor;

[0018] Based on the outer surface of the cable core, the corrugated conductor is longitudinally wrapped and rounded to obtain a corrugated round tube, wherein the cable core includes an inner conductor and a foamed insulation layer wrapped around the outer peripheral surface of the inner conductor;

[0019] Preheat the corrugated round tube within the temperature range of 120°C to 180°C, and weld the longitudinal connection edges of the corrugated round tube to obtain an outer conductor with a seamless outer peripheral surface.

[0020] As a further preference, during the above welding process, the corrugated round tube is drawn to the welding gun head for welding treatment. Moreover, first, the real-time height information of the pre-welding area on the surface of the corrugated round tube is collected, and based on the real-time height information, the height of the welding gun head is adjusted so that the height of the welding gun head and the outer surface contour of the corrugated round tube always remain at the same relative height position.

[0021] Generally speaking, compared with the prior art, the above technical solution conceived by this application mainly has the following technical advantages:

[0022] 1. Through the structural design of the corrugated structure of the outer conductor of this RF cable, the inverted V-shaped peaks in the outer conductor sink into the foamed insulating layer to form a physical bite, preventing relative sliding or separation between the outer conductor and the foamed insulating layer. The foamed insulating layer is accommodated in the tooth grooves with an arc-shaped bottom, weakening the generation of gaps, thereby reducing the reflection generated when the electromagnetic signal conducted from the inner conductor to the outer conductor passes through different cut-off layers, improving the voltage standing wave ratio and transmission loss performance. Especially for the improvement of TE electromagnetic waves exceeding the cut-off frequency, it is particularly obvious. Under the same size specifications, based on the RF cable of this design, this RF coaxial cable has the ability of low loss, low standing wave and operation beyond the cut-off frequency, which is beneficial to meeting the low loss, low standing wave and high frequency requirements during mobile communication networking.

[0023] 2. During the manufacturing process of the inner conductor of this RF cable, the corrugated round tube is preheated within the temperature range of 120°C to 180°C, so that the corrugated round tube can appropriately sink into the foamed insulating layer, promoting the combination of the foamed insulating layer and the corrugated round tube, and reducing the thickness of the gap (i.e., the radial gap) between the outer conductor and the foamed insulating layer. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of a low-loss, low-standing-wave, and ultra-cut-off-frequency RF coaxial cable provided by an embodiment of this application;

[0025] Figure 2 is a cross-sectional view of the outer conductor provided by an embodiment of this application;

[0026] Figure 3 is a manufacturing process flow chart of the outer conductor provided by an embodiment of this application;

[0027] Figure 4 is a voltage standing wave ratio test chart of an existing RF coaxial cable provided by this application;

[0028] Figure 5 is a loss test diagram of an existing radio frequency coaxial cable provided by this application;

[0029] Figure 6 is a voltage standing wave ratio test diagram of a low-loss, low-standing-wave, super-cutoff-frequency radio frequency coaxial cable provided by an embodiment of this application;

[0030] Figure 7 is a loss test diagram of a low-loss, low-standing-wave, super-cutoff-frequency radio frequency coaxial cable provided by an embodiment of this application.

[0031] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0032] 1. Inner conductor; 2. Foamed insulation layer; 3. Outer conductor; 4. Sheath layer; 5. Inverted V-shaped peak tip; 6. Arc-shaped groove bottom; 10. Radial gap. Detailed implementation manners

[0033] In order to make the objectives, technical solutions and advantages of this application clearer, the following further elaborates on this application in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0034] The following further elaborates on this application in conjunction with the Figures 1-7 drawings.

[0035] An embodiment of this application discloses a low-loss, low-standing-wave, super-cutoff-frequency radio frequency coaxial cable. Referring to Figures 1-2 , the low-loss, low-standing-wave, super-cutoff-frequency radio frequency coaxial cable sequentially includes an inner conductor 1, a foamed insulation layer 2, an outer conductor 3, and a sheath layer 4 from the inside to the outside, where: the outer conductor 3 is an annular corrugated tube with a corrugated structure, and the surface of the corrugated structure facing the foamed insulation layer 2 is alternately provided with tooth peaks and tooth grooves along the axial direction. The tooth peaks and tooth grooves are smoothly connected, the tooth peaks have inverted V-shaped peak tips 5 for sinking into the foamed insulation layer 2, and the tooth grooves have arc-shaped groove bottoms 6 for accommodating the foamed insulation layer 2.

[0036] Generally speaking, in a radio frequency coaxial cable, a radial gap 10 is formed between the outer conductor 3 and the foamed insulation layer 2, and the transmission speed of electromagnetic waves in the foamed insulation layer 2 , c is the speed of light, v is the relative transmission rate, and v generally takes a value of 0.8 - 0.95. The radial gap 10 between the foamed insulation layer 2 and the outer conductor 3 is air, and its transmission speed is approximately equal to the speed of light c. When high-order harmonic TE electromagnetic waves are transmitted in different media, the direction of their magnetic fields changes and reflections occur, resulting in the deterioration of the standing wave and attenuation performance of the radio frequency coaxial cable after the cutoff frequency.

[0037] Therefore, in this design solution, by specifically designing the corrugated structure of the outer conductor 3, after the outer conductor 3 is tightly coated around the outer circumference of the foamed insulation layer 2, the inverted V-shaped peak tips 5 in the outer conductor 3 can penetrate into the foamed insulation layer 2 to form a physical bite, preventing relative sliding or separation between the outer conductor 3 and the foamed insulation layer 2, and the tooth grooves with an arc-shaped bottom can accommodate the foamed insulation layer 2, weakening the generation of the radial gap 10. This is beneficial to reducing the reflection generated when the electromagnetic signal flowing from the inner conductor 1 to the outer conductor 3 passes through different cut-off layers, improving the voltage standing wave ratio and transmission loss performance, especially for the improvement of the TE electromagnetic wave exceeding the cut-off frequency is particularly obvious, enabling this radio frequency coaxial cable to have the ability of low loss, low standing wave and operating at frequencies above the cut-off frequency, and can provide a wider operating frequency under large-size conditions, meeting the requirements of low loss, low standing wave and high frequency in mobile communication networking.

[0038] In addition, the arc-shaped bottom 6 of the tooth groove can also help to provide space when the cable is bent, avoid extrusion damage to the foamed insulation layer 2, and play a buffering role in the bending deformation of the cable, so as to ensure the long-term stable use of the cable.

[0039] It can be understood that the outer conductor 3 is made into an annular corrugated tube with a corrugated structure by a corrugating process. Under the corrugating process, the surface of the outer conductor 3 facing away from the foamed insulation layer 2 (i.e., the outer surface) basically presents the same specifications of tooth peaks, tooth grooves and corrugation depths as the surface of the corrugated structure facing the foamed insulation layer 2 (i.e., the inner surface). The tooth peaks and tooth grooves described subsequently mainly refer to the tooth peaks and tooth grooves on the inner surface of the outer conductor 3.

[0040] Furthermore, in some embodiments, the corrugation depth of the outer conductor 3 satisfies the following relational expression:

[0041]

[0042]

[0043]

[0044] Wherein, represents the corrugation depth, represents the radius of the arc of the arc-shaped bottom 6, represents the corrugation pitch of the outer conductor 3, represents the angle between the inverted V-shaped peak tip 5 and the axis of the outer conductor 3.

[0045] Under this design, by designing the ranges of the relevant arc radius and angle in the corrugated profile of the outer conductor 3 and coupling the geometric structures of the inverted V-shaped peak tip 5 and the arc-shaped bottom 6, a better balance can be achieved between the piercing and anchoring effect of the inverted V-shaped peak tip 5 and the deformation buffering effect of the arc-shaped bottom 6.

[0046] For a cable, if the inverted V-shaped peak tip 5 is too sharp, the inverted V-shaped peak tip 5 may pierce the foamed insulation layer 2; if the inverted V-shaped peak tip 5 is too gentle, the biting effect between the inverted V-shaped peak tip 5 and the foamed insulation layer 2 is poor. Therefore, setting the included angle between can obtain a larger penetration depth to obtain good anchoring force, and will not damage the foamed insulation layer 2.

[0047] For the arc-shaped groove bottom 6, if the curvature of the groove bottom is too large, stress concentration is likely to occur when the cable is bent, which is likely to cause fatigue fracture. If the groove bottom is too shallow, the accommodation capacity for the foamed insulation layer 2 is weakened. Therefore, under the above relational expression values, the depth of the arc-shaped groove is appropriate, which can better balance flexibility and strength. And the formed radial gap 10 is often small, and the radial gap 10 (i.e., the gap thickness between the outer conductor 3 and the foamed insulation layer 2) between the outer conductor 3 and the foamed insulation layer 2 can basically reach 0.2 mm - 0.8 mm.

[0048] Preferably, in some embodiments, the corrugation pitch of the outer conductor 3 is 2 mm - 4 mm, and the radial gap 10 between the outer conductor 3 and the foamed insulation layer 2 is less than 1 mm. Further, the range of the radial gap 10 between the outer conductor 3 and the foamed insulation layer 2 is 0.2 mm - 0.8 mm.

[0049] Under this design, based on the corrugated structure of the outer conductor 3, the compression ratio of the outer conductor 3 can reach 1.005 - 1.05, so that while ensuring that the cable meets the bending radius requirements of engineering parameters, the gap (i.e., the air layer thickness) between the outer conductor 3 and the foamed insulation layer 2 can be made smaller, which is beneficial to reducing the reflection generated when the electromagnetic signal flowing from the inner conductor 1 to the outer conductor 3 passes through different cut-off layers, thereby improving the voltage standing wave ratio and transmission loss performance, especially for TE electromagnetic waves exceeding the cut-off frequency. It should be noted that the control of the radial gap between the outer conductor 3 and the foamed insulation layer 2 can be achieved based on the above-mentioned outer conductor 3's outer shape structure design, or can be achieved based on the manufacturing method, or can be jointly achieved based on the optimization of the outer conductor 3's outer shape structure design and manufacturing method.

[0050] Further, as Figure 3 shown, in some embodiments, the outer conductor 3 is obtained by the following method:

[0051] S1: Corrugate the smooth strip of the outer conductor with a preset corrugation shape to obtain a corrugated conductor.

[0052] Generally, first unwind the smooth strip of the outer conductor, and then corrugate the smooth strip of the outer conductor according to the required corrugation pitch and corrugation shape.

[0053] S2: Based on the outer surface of the cable core, longitudinally wrap and round the corrugated conductor to obtain a corrugated round tube, at this time the corrugated round tube wraps the outer surface of the cable core. Among them, the cable core includes an inner conductor 1 and a foamed insulation layer 2 wrapped around the outer peripheral surface of the inner conductor 1.

[0054] S3: Preheat the corrugated round tube in the temperature range of 120°C to 180°C.

[0055] In this process, preheating the corrugated round tube can soften the foamed insulation layer 2 inside the round tube, so that the foamed insulation layer 2 can appropriately sink into the corrugated round tube, promoting the combination of the foamed insulation layer 2 and the corrugated round tube, and reducing the thickness of the radial gap 10.

[0056] S4: Weld the longitudinal connection edges of the corrugated round tube (that is, use the connection edges of the belt as the pre-welding place for welding operations) to obtain an outer conductor 3 with a seamless outer peripheral surface (that is, a seamless corrugated round tube).

[0057] In step S4, the corrugated round tube is pulled to the welding gun head for welding treatment. And before the welding treatment, first collect the real-time height information of the pre-welding place on the surface of the corrugated round tube through a sensor. Based on the real-time height information detected by the sensor, and transmit the real-time height information to the controller through the sensor. Then the controller dynamically controls the displacement device based on the real-time height information, and adjusts the height of the welding gun head in real time through the position device, so that the height of the welding gun head and the outer surface contour of the corrugated round tube always maintain the same relative height position (that is, control that the distance between the welding gun head and the corrugated contour of the corrugated round tube always remains at a specified distance, and this distance is pre-selected and set by the operator).

[0058] S5: Take up (wind up) the outer conductor 3 wrapped with the inner conductor 1 and the foamed insulation layer 2.

[0059] For easy understanding, Figure 4 shows an existing inch specification radio frequency coaxial cable (which can be selected from the inch standard specification cable specified in the industry standard YD / T1092). From Figure 4 it can be seen that this cable has interference peaks at 3.3 GHz - 3.7 GHz after the cut-off frequency, resulting in the inability of this cable to work in the 3.3 GHz - 3.7 GHz frequency band. In a certain test, it was measured that the average radial gap 10 between the outer conductor 3 and the foamed insulation layer 2 in this cable is 1.8 mm.

[0060] In addition, Figure 5 shows the loss test diagram of the existing inch specification radio frequency coaxial cable. From Figure 5It can be seen that the loss index (i.e., attenuation performance) of the existing cable starts to fluctuate violently after 2.8 GHz, indicating that the loss fluctuation is large and unstable, resulting in a large loss of the cable after 2.8 GHz and making it difficult to use.

[0061] Figure 6 Shows the standing wave ratio test diagram of a inch - sized radio frequency coaxial cable made based on this design. The difference between this cable and the above - mentioned existing radio frequency coaxial cable is that the outer conductor 3 of this cable is an annular corrugated tube with a corrugated structure. On one side surface of the corrugated structure facing the foamed insulation layer 2, tooth peaks and tooth grooves are alternately arranged along the axial direction. The tooth peaks and tooth grooves are smoothly connected. The tooth peak has an inverted V - shaped peak tip 5 for sinking into the foamed insulation layer 2, and the tooth groove has an arc - shaped groove bottom 6 for accommodating the foamed insulation layer 2. Among them, the corrugation depth H is 0.51 mm, the arc radius R of the arc - shaped groove bottom 6 is 0.5 mm, the angle between the tooth groove surface and the axis is 20°, the pitch P is 3 mm, the compression ratio is 1.015, and the average radial gap 10 between the outer conductor 3 and the foamed insulation layer 2 of the final product is 0.3 mm.

[0062] From Figure 6 it can be seen that the standing wave Figure 3 interference peak at 3.3 GHz - 3.7 GHz is greatly reduced (almost disappears), indicating that the cable can continue to work after the cut - off frequency, that is, the working frequency of the cable is broadened, basically meeting the requirements of the 5G working frequency band.

[0063] In addition, Figure 7 shows the loss test diagram of the above - mentioned inch - sized radio frequency coaxial cable made based on this design. From Figure 7 it can be seen that the attenuation performance of this cable starts to show small fluctuations after 2.8 GHz, but the loss fluctuation is small and relatively stable, indicating that the loss is small and the cable can still be used after 2.8 GHz.

[0064] It should be noted that Figure 4 and Figure 6 in the voltage standing wave ratio test diagrams shown, the abscissa represents the test frequency of the standing wave, the ordinate represents the test value of the standing wave. In the figure, "Trl" represents "test window", "SWR" represents "voltage standing wave ratio", "S11" represents "instrument test port", "Ref" represents "bottom line value", "Start" represents "starting frequency", "Stop" represents "ending frequency", and "Cor" represents "calibrated state".

[0065] Figure 5 and Figure 7In the loss test chart shown, the horizontal axis represents the test frequency of attenuation, and the vertical axis represents the test value of attenuation. In the chart, "Trl" represents "test window", "S21" represents "instrument test port", "Log Mag" represents "attenuation index", "Ref" represents "baseline value", "Start" represents "starting frequency", "Stop" represents "ending frequency", and "IFBW" represents "sweeping frequency bandwidth".

[0066] It should be understood that expressions such as "including" and "may include" used in this application indicate the existence of disclosed functions, operations, or components, and do not limit the existence of one or more additional functions, operations, and components. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, component, assembly, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, components, assemblies, or a combination thereof.

[0067] It should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0068] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" means two or more, unless otherwise specifically defined.

[0069] In this application, unless otherwise clearly specified and limited, terms such as "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0070] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable, characterized in that: The cable comprises, from the inside to the outside, an inner conductor (1), a foamed insulation layer (2), an outer conductor (3) and a sheath layer (4), wherein: The outer conductor (3) is an annular corrugated tube with a corrugated structure, wherein a surface of the corrugated structure facing the foamed insulation layer (2) is alternately provided with tooth peaks and tooth grooves along the axial direction, the tooth peaks having an inverted V-shaped peak tip (5) for sinking into the foamed insulation layer (2), and the tooth grooves having an arc-shaped groove bottom (6) for accommodating the foamed insulation layer (2); The corrugation depth of the outer conductor (3) satisfies the following relationship: in, Indicates the corrugation depth, represents the arc radius of the arc groove bottom (6), represents the corrugation pitch of the outer conductor (3), It represents the angle between the surface of the tooth groove and the axis of the outer conductor (3).

2. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to claim 1, characterized in that: The corrugation pitch of the outer conductor (3) is 2 mm to 4 mm.

3. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to claim 1, characterized in that: A radial gap (10) between the outer conductor (3) and the foamed insulating layer (2) is less than 1 mm.

4. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to claim 3, characterized in that: The radial gap (10) between the outer conductor (3) and the foamed insulating layer (2) is 0.2 mm to 0.8 mm.

5. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to claim 1, characterized in that: The compression ratio of the outer conductor (3) is 1.005-1.

05.

6. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to any one of claims 1 to 5, characterized in that: The outer conductor (3) is prepared by the following method: Corrugating the smooth outer conductor strip in a preset corrugation shape to obtain a corrugated conductor; The corrugated conductor is longitudinally rolled up based on the outer surface of the cable core to obtain a corrugated round tube, wherein the cable core comprises an inner conductor (1) and a foamed insulating layer (2) wrapped around the outer circumference of the inner conductor (1); The corrugated round tube is preheated in a temperature range of 120°C to 180°C, and the longitudinal connecting edges of the corrugated round tube are welded to obtain an outer conductor (3) with no gaps on the outer circumference.

7. The low-loss, low-standing-wave, ultra-cut-off frequency radio frequency coaxial cable according to claim 6, characterized in that: When executing the above welding process, the corrugated round tube is pulled to the welding gun head for welding processing, and the real-time height information of the pre-welding point on the surface of the corrugated round tube is first collected, and the height of the welding gun head is adjusted based on the real-time height information, so that the height of the welding gun head and the outer surface contour of the corrugated round tube are always maintained at the same relative height position.

Images