Super cut-off frequency radio frequency coaxial cable

Abstract

The invention belongs to the technical field of wireless communication, and relates to a super cut-off frequency radio frequency coaxial cable. The coaxial cable sequentially comprises an inner conductor, an insulating layer, an outer conductor and a sheath layer from inside to outside, the inner conductor is designed to be a spiral corrugated pipe, the tooth shape of the inner conductor is designed to be a square waveform with a round chamfer, the inductance can be improved, the high-frequency signal phase can be delayed, and high-order mode excitation can be effectively weakened. The radio frequency coaxial cable can continue to work after exceeding the cut-off frequency, wide working frequency is provided under the condition of large specification and size, and the requirements for low loss, large coverage range and high frequency during mobile communication networking are met. A standing wave diagram of the product shows that the interference peak value of 3.3 GHz-3. 7GHz is greatly reduced and even basically disappears, so that the radio frequency coaxial cable can continue to work at the stage of 3.3 GHz-3. 7GHz after exceeding the cut-off frequency.

Description

Technical Field

[0001] The present application belongs to the technical field of wireless communication and relates to a super-cutoff frequency radio frequency coaxial cable. Background Art

[0002] Radio frequency coaxial cable can be used for mobile communication meter wave, decimeter wave, centimeter wave and other band signal transmission. It is an important component of the antenna system and is mostly used for radio frequency signal transmission between mobile base stations and antennas.

[0003] In the related technology, the operating frequency of the cable is greatly affected by the cutoff frequency of the cable. When the cable exceeds a certain size, it is affected by high-order harmonics. After exceeding the cutoff frequency, the standing wave and transmission loss performance of the RF coaxial cable are seriously deteriorated, making it difficult to use after exceeding the cutoff frequency, making the operating frequency of the cable low; for example, traditional The cut-off frequency of the coaxial cable with a certain specification is about 2.7GHz, which cannot meet the high operating frequency requirements of mobile communications. Therefore, when building a mobile communication network, only small-specification coaxial cables that can provide higher frequencies can be selected. However, compared with large-specification coaxial cables, small-specification coaxial cables often have greater transmission losses, which may greatly reduce the coverage range of mobile communication equipment. Summary of the invention

[0004] In response to the defects or improvement needs of the prior art, the present application provides a super-cutoff frequency RF coaxial cable, which can continue to work normally after exceeding the cutoff frequency, and can provide a higher operating frequency under large-size conditions, meeting the requirements of low loss, large coverage and high frequency in mobile communication networking.

[0005] The present application provides a super-cutoff frequency radio frequency coaxial cable, which comprises an inner conductor, an insulating layer, an outer conductor and a sheath layer from the inside to the outside, wherein: The inner conductor is a spiral corrugated tube with a thread structure, the tooth shape of the thread structure is a square wave with rounded chamfers, and The corrugation pitch of the inner conductor fluctuates periodically along the axial direction, or the compression ratio of the inner conductor fluctuates periodically along the axial direction.

[0006] Through the above technical scheme conceived by the present application, compared with the prior art, the present design can effectively improve the compression ratio of the inner conductor, enhance the inductance of the inner conductor, delay the phase of the high-frequency signal, and effectively weaken the excitation of the high-order mode by designing the inner conductor as a spiral corrugated tube and designing its tooth shape as a square waveform with rounded chamfers; and based on the cable with this tooth shape design, the direction of the current in the cable will be basically perpendicular to the axis of the cable, or parallel to the axis of the cable, which makes the current transmission direction of the inner conductor more regular and accurate. Under these effects, the transmission direction of the interference signal generated by the high-order mode in the cable will be clearer and controllable.

[0007] In addition, since the corrugation pitch of the inner conductor fluctuates periodically along the axial direction (or the compression ratio of the inner conductor fluctuates periodically along the axial direction), the reflections of each frequency point after exceeding the cutoff frequency are not periodically superimposed, so that the reflections of each frequency point are regularly disrupted, thereby effectively weakening the excitation of high-order modes and suppressing the interference of high-order harmonics on the coaxial cable. This widens the operating frequency of the cable and allows the cable to continue to work effectively after exceeding the cutoff frequency, thereby enabling the cable to provide a wider operating frequency under large-size conditions, meeting the requirements of low loss, large coverage and high frequency in mobile communication networking.

[0008] As a further preferred embodiment, the thread structure comprises a crest section and a bottom section, wherein: The axial length of the tooth peak section is greater than the axial length of the tooth bottom section; The sum of the axial length of the tooth peak section and the axial length of the tooth bottom section is equal to the corrugation pitch of the inner conductor.

[0009] As a further preferred embodiment, the tooth bottom segment and the tooth peak segment satisfy the following relationship:

[0010] Wherein, X represents the axial length of the tooth base segment, and Y represents the axial length of the tooth peak segment.

[0011] As a further preferred embodiment, the side wall surfaces of the tooth bottom section and the tooth peak section include a tooth bottom chamfered section, a linear flat section and a tooth peak chamfered section, and the tooth bottom chamfered section, the linear flat section and the tooth peak chamfered section are smoothly connected in sequence from inside to outside along the radial direction of the inner conductor.

[0012] As a further preferred embodiment, the thread depth of the thread structure satisfies the following relationship:

[0013]

[0014]

[0015] Wherein, D represents the tooth depth, R1 represents the radial length of the tooth bottom chamfered section, R2 represents the radial length of the tooth peak chamfered section, and L represents the radial length of the linear flattened section.

[0016] As further preferred, the corrugation pitch of the inner conductor satisfies the following relationship:

[0017] Where P represents the corrugation pitch of the inner conductor, A is a fixed constant, is the phase angle parameter, The value range is 0~2π, It is a pre-set standard corrugation pitch.

[0018] As a further preference, in the same periodic fluctuation change, the corrugation pitch / compression ratio of the inner conductor first changes from large to small and then changes from small to large, or the corrugation pitch / compression ratio of the inner conductor first changes from small to large and then changes from large to small.

[0019] As further preferred, the inner conductor is a single-helix spiral corrugated tube, or the inner conductor is a double-helix spiral corrugated tube.

[0020] As a further preferred embodiment, the inner conductor with a corrugation pitch that fluctuates periodically along the axial direction is manufactured in the following manner: The inner conductor smooth strip is rolled and welded to obtain a smooth inner conductor round tube; The smooth inner conductor round tube is pulled at a pulling speed that fluctuates periodically, and a concentric corrugating blade with a circular arc angle is used to corrugate the smooth inner conductor round tube to obtain an inner conductor.

[0021] As a further preference, the radio frequency coaxial cable is a radio frequency coaxial cable with a specification of 7 / 8 inches or above.

[0022] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art: 1. The spiral structure of the inner conductor of the cable of the present application is set to a square waveform, and the corrugation pitch of the inner conductor is periodically fluctuated along the axial direction (or the compression ratio of the inner conductor is periodically fluctuated along the axial direction), so that the reflections of each frequency point of the cable after exceeding the cut-off frequency are not periodically superimposed, and the reflections of each frequency point are regularly disrupted, thereby effectively weakening the excitation of high-order modes, suppressing the interference of high-order harmonics on the coaxial cable, and broadening the working frequency of the cable, so that the cable can continue to work effectively after exceeding the cut-off frequency, so that the cable can provide a wider working frequency with a larger specification size, so as to meet the requirements of low loss, large coverage and high frequency in mobile communication networking.

[0023] 2. The ratio of the axial length of the inner conductor's tooth bottom section to the axial length of the tooth peak section is set at to It can ensure that the cable can achieve performance advantages under complex constraints such as electrical performance and mechanical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a single-helix super-cutoff frequency radio frequency coaxial cable provided in an embodiment of the present application; Figure 2It is a schematic structural diagram of a double-helix super-cutoff frequency radio frequency coaxial cable provided in an embodiment of the present application; Figure 3 It is a schematic diagram showing the square wave tooth shape of the thread structure; Figure 4 It is a distribution diagram of the tooth bottom chamfer section, the linear flattening section and the tooth peak chamfer section provided in the embodiment of the present application; Figure 5 is a manufacturing process flow chart of an inner conductor provided in an embodiment of the present application; Figure 6 This is a voltage standing wave ratio test diagram of an existing radio frequency coaxial cable provided in an embodiment of the present application; Figure 7 This is a voltage standing wave ratio test diagram of a super-cutoff frequency radio frequency coaxial cable provided in an embodiment of the present application.

[0025] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Inner conductor; 2. Insulation layer; 3. Outer conductor; 4. Sheath layer; 5. Tooth peak section; 6. Tooth bottom section; 7. Tooth bottom chamfered section; 8. Linear flat section; 9. Tooth peak chamfered section. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] The following is combined with Figure 1-Figure 7 This application is described in further detail.

[0028] The present application embodiment discloses a super cut-off frequency radio frequency coaxial cable. Figure 1-Figure 2 The super-cutoff frequency radio frequency coaxial cable comprises an inner conductor 1, an insulating layer 2, an outer conductor 3 and a sheath layer 4 from the inside to the outside, wherein the inner conductor 1 is a spiral corrugated tube with a threaded structure, the tooth shape of the threaded structure is a square waveform with a rounded chamfer, and the corrugation pitch of the inner conductor 1 fluctuates periodically along the axial direction, or the compression ratio of the inner conductor 1 fluctuates periodically along the axial direction.

[0029] Under this design, by designing the inner conductor 1 as a spiral corrugated tube and designing its tooth shape as a square waveform with rounded chamfers, the compression ratio of the inner conductor 1 can be effectively improved, the inductance of the inner conductor 1 can be enhanced, the phase of the high-frequency signal can be delayed, and the excitation of the high-order mode can be effectively weakened; and based on the cable with this tooth shape design, the direction of the current in the cable will be basically perpendicular to the cable axis, or basically parallel to the cable axis, which makes the current transmission direction of the inner conductor 1 more regular and precise. Under these effects, the transmission direction of the interference signal generated by the high-order mode in the cable will be clearer and more controllable.

[0030] In addition, since the corrugation pitch of the inner conductor 1 fluctuates periodically along the axial direction (or the compression ratio of the inner conductor 1 fluctuates periodically along the axial direction), the reflections of each frequency point after exceeding the cutoff frequency are not periodically superimposed, and the reflections of each frequency point are regularly disrupted, thereby effectively weakening the excitation of the high-order mode, suppressing the interference of high-order harmonics on the coaxial cable, and improving the inductance, so that the RF coaxial cable under this structural design can continue to work effectively after exceeding the cutoff frequency, and the operating frequency is expanded. Compared with traditional RF coaxial cables, this RF coaxial cable can provide a wider operating frequency under the same specifications and dimensions, so as to meet the requirements of low loss, large coverage and high frequency in mobile communication networking. In particular, the present design is particularly suitable for RF coaxial cables of 7 / 8 inches and above, that is, preferably, the present RF coaxial cable is a RF coaxial cable of 7 / 8 inches and above.

[0031] Further, such as Figure 3 As shown, in some embodiments, the thread structure of the inner conductor 1 is obtained by a corrugation process, wherein the thread structure includes a crest segment 5 and a bottom segment 6, and the crest segment 5 and the bottom segment 6 are alternately arranged along the axial direction of the inner conductor 1.

[0032] Preferably, the axial length of the tooth peak segment 5 is greater than the axial length of the tooth bottom segment 6 , and the sum of the axial lengths of the tooth peak segment 5 and the axial lengths of the tooth bottom segment 6 is equal to the corrugation pitch of the inner conductor 1 .

[0033] Further, such as Figure 4 As shown, in some embodiments, the side wall surfaces of the tooth bottom segment 6 and the tooth peak segment 5 include a tooth bottom chamfered segment 7, a linear flat segment 8 and a tooth peak chamfered segment 9, and the tooth bottom chamfered segment 7, the linear flat segment 8 and the tooth peak chamfered segment 9 are smoothly connected in sequence from the inside to the outside along the radial direction of the inner conductor 1.

[0034] Further, in some embodiments, in the same periodic fluctuation change, the corrugation pitch / compression ratio of the inner conductor 1 first changes from large to small, and then changes from small to large. In some other embodiments, in the same periodic fluctuation change, the corrugation pitch / compression ratio of the inner conductor 1 first changes from small to large, and then changes from large to small.

[0035] Under this design, by regularly controlling the corrugation pitch or compression ratio of the inner conductor 1, the interference of high-order harmonics on the coaxial cable can be reduced, so that the cable can continue to work effectively after exceeding the cut-off frequency.

[0036] It should be clear that when the corrugation pitch of the inner conductor 1 is designed to fluctuate periodically along the axial direction, since the sum of the axial length of the tooth bottom section 6 and the axial length of the tooth peak section 5 is equal to the corrugation pitch, the axial length of the tooth bottom section 6 and the axial length of the tooth peak section 5 in the inner conductor 1 will also change along with the change of the corrugation pitch. That is, when the corrugation pitch of the inner conductor 1 fluctuates periodically along the axial direction, it is preferred to select the ratio of the axial length of the tooth bottom section 6 to the axial length of the tooth peak section 5 as a fixed ratio value, and then calculate the axial length of the tooth bottom section 6 and the axial length of the tooth peak section 5 based on this fixed ratio value and the actual value of the corrugation pitch.

[0037] It is clear that when designing the compression ratio of the inner conductor 1 to fluctuate periodically along the axial direction, it is preferred to set the depth of the inner conductor 1 to fluctuate periodically along the axial direction to achieve the purpose of periodic fluctuation of the compression ratio of the inner conductor 1.

[0038] Furthermore, in some specific embodiments, the axial lengths of the tooth crest segment 5 and the tooth bottom segment 6 are set to satisfy the following relationship:

[0039]

[0040] Wherein, X represents the axial length of the tooth bottom section 6 , Y represents the axial length of the tooth peak section 5 , and P represents the corrugation pitch of the inner conductor 1 .

[0041] It should be noted that the ratio of the axial length of the tooth bottom segment 6 to the axial length of the tooth peak segment 5 is taken as to It is an optimal design result that takes into account the influence of many factors.

[0042] Specifically, in the RF coaxial cable, the tooth peak section 5 of the inner conductor 1 will serve as the main current carrying area, and its length proportion needs to dominate the electric field distribution, which makes the proportion control of the tooth peak section 5 and the tooth bottom section 6 have a greater impact on the electrical performance of the cable. For the inner conductor, since the high-frequency current is concentrated on the surface of the inner conductor 1 due to the skin effect, setting the axial length of the tooth peak section 5 longer can increase the effective surface area of ​​the inner conductor 1, reduce high-frequency resistance, and reduce signal attenuation.

[0043] In addition, in the cable, the longer (dominant) tooth peak section 5 can provide better structural rigidity for the inner conductor 1 and enhance the inner conductor 1's ability to resist external extrusion; at the same time, combined with the small round chamfer design in the threaded structure, the inner conductor 1 exerts less pressure on the insulating layer 2 and is less likely to produce indentations.

[0044] As for the tooth bottom section 6, if the tooth bottom section 6 is too short, it will cause local distortion of the electric field, and if the tooth bottom section 6 is too long, it may weaken the regulating effect of the thread on the field distribution. A moderate tooth bottom section 6 can better serve as a buffer zone to disperse the bending stress and avoid stress concentration in a single position to cause metal fatigue fracture. This can make the cable more flexible and increase the bending fatigue life of the cable.

[0045] In addition, it is found in actual production that since the inner conductor 1 needs to use a corrugating tool to produce the threaded structure, a too short tooth bottom section 6 is often difficult to process; moreover, a too short tooth bottom section 6 will increase the local stress of the corrugating tool and accelerate tool wear. Moreover, a too short tooth bottom section 6 is prone to burrs during manufacturing, which makes the length control of the tooth bottom section 6 have a greater impact on the feasibility and manufacturing cost of the corrugation process.

[0046] In addition, considering that the axial lengths of the tooth bottom section 6 and the tooth peak section 5 are related to the corrugation pitch of the inner conductor 1, by taking the ratio of the axial length of the tooth bottom section 6 to the axial length of the tooth peak section 5 as ~ , which can ensure that the axial length of the tooth bottom section 6 and the axial length of the tooth peak section 5 are relatively appropriate, so that the cable can have more advantageous performance under complex constraint conditions.

[0047] Further, in some embodiments, the thread depth of the thread structure is as follows:

[0048]

[0049]

[0050] Wherein, D represents the current tooth depth, R1 represents the radial length of the tooth bottom chamfer section 7, R2 represents the radial length of the tooth peak chamfer section 9, and L represents the radial length of the linear flat section 8; preferably, the tooth bottom chamfer section 7 and the tooth peak chamfer section 9 are both 90-degree chamfers, wherein the radial length of the tooth bottom chamfer section 7 and the radial length of the tooth peak chamfer section 9 are the chamfer radius, preferably, = .

[0051] In this design, by controlling the size of the round chamfer of the thread structure within a specific range, the inner conductor 1 can be prevented from crushing the insulating layer 2, and the round chamfer of the thread structure has little effect on the direction of the current in the cable.

[0052] Specifically, in some embodiments, when the corrugation pitch of the inner conductor 1 fluctuates periodically along the axial direction, the corrugation pitch of the inner conductor 1 satisfies the following relationship:

[0053] Wherein, P represents the corrugation pitch of the inner conductor 1, A is a fixed constant, and the selection range of A is 0.02-0.05; is the phase angle parameter, The value range of is 0~2π, which is used to generate the cosine function waveform of the periodic variation of the corrugation pitch; It is a pre-set standard corrugation pitch, which can be selected based on existing specifications and standards, such as based on relevant design standard provisions in the industry standard YD / T1092.

[0054] Preferably, A is 0.03. The cable is periodically accumulated in increments of ΔΦ=5°~10° in the axial direction (where 0~360° corresponds to a complete waveform cycle), and a cycle is completed every 20 meters~50 meters along the axial length of the cable. Preferably, in one cycle, Take 5 degrees as the change amount and periodically accumulate the value (for example, = , n = 0 degree, 1 degree, 2 degrees, 3 degrees, etc.), and the phase angle is accumulated by 5 degrees every 0.5 meters along the axial direction of the cable.

[0055] In this design, the variation of the corrugation pitch of the inner conductor 1 is controlled by using the cosine function variation rule, which can prevent the reflection of other frequency points caused by the frequency doubling superposition characteristics due to the linear variation, and the process is relatively simple to implement.

[0056] Furthermore, in some embodiments, the inner conductor 1 is a single-helix spiral corrugated tube. In some other embodiments, the inner conductor 1 can also be a double-helix spiral corrugated tube. Compared with the single-thread design, the inner conductor 1 with a double-helix design has better cable bending performance and a larger compression ratio, and its inductance is stronger and the electrical performance is better.

[0057] Further, such as Figure 5 As shown, in some embodiments, an inner conductor 1 with a corrugation pitch that fluctuates periodically along the axial direction is manufactured by the following steps: S1: Roll and weld the inner conductor smooth strip to obtain a smooth inner conductor round tube.

[0058] Generally speaking, the inner conductor smooth tape is first unwound, and then the conductor smooth tape is rolled into a round shape. Then, the rolled inner conductor smooth tape is pulled to a welding station and welded by a welding device to obtain a smooth inner conductor round tube.

[0059] S2: A traction device is used to pull a smooth inner conductor round tube at a periodically fluctuating traction speed, and a concentric corrugating blade with a circular arc angle is used to corrugate the smooth inner conductor round tube to obtain an inner conductor 1 in the form of a spiral corrugated tube with a square wave thread structure and a corrugation pitch that fluctuates periodically along the axial direction, and then the inner conductor 1 is wound (reeled).

[0060] In this step, it is preferred to collect the real-time linear speed of the smooth inner conductor round tube through a speed encoder, and use a variable frequency motor to pull the inner conductor 1 according to a set speed change rule, so that the corrugation pitch changes according to a predetermined change rule; at the same time, a concentric small arc angle corrugating blade is used to roll out a spiral structure with a square tooth cross-section.

[0061] For ease of understanding, Figure 6 Shows a traditional inches (i.e. ) Specifications of RF coaxial cable (selected from the 1 specified in the industry standard YD / T1092 Inch standard cable) standing wave ratio test chart, by Figure 6 It can be seen that the traditional cable (i.e., the existing cable) has an obvious interference peak at 3.3GHz-3.7GHz after the cutoff frequency.

[0062] Figure 7 A 1 based on this design is shown inches (i.e. ) RF coaxial cable, which is different from the above-mentioned traditional RF coaxial cable in that: the inner conductor 1 of the cable is a spiral corrugated tube with a threaded structure, the tooth shape of the threaded structure is a square waveform with rounded chamfers, and the depth of the inner conductor 1 fluctuates periodically along the axial direction (that is, the periodic fluctuation of the compression ratio is achieved by the periodic fluctuation of the depth).

[0063] The depth of the inner conductor 1 is 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, and 2.4 mm; and the depth changes periodically in the order of 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.3 mm, 2.2 mm, 2.1 mm, and 2.0 mm.

[0064] The corrugation pitch of the inner conductor 1 is 10.2 mm, and the ratio of the axial length of the tooth bottom section 6 to the axial length of the tooth peak section 5 is: ; The axial length of the tooth bottom segment 6 is 3.06mm, and the axial length of the tooth peak segment 5 is 7.14mm.

[0065] The round chamfer of the thread structure is a 90-degree chamfer, and the radius of the round chamfer and the radial length of the linear flat section 8 are selected according to the real-time depth of the inner conductor 1, and the value is = = When the depth is 2.0 mm, the radial length of the linear flat section 8 is The chamfer radius of the tooth bottom chamfer section 7 is 1.5 mm. The chamfer radius of the tooth peak chamfer section 9 is 0.25 mm. It is 0.25mm.

[0066] The standing wave of the super cut-off frequency RF coaxial cable Figure 3 The 3GHz-3.7GHz interference peak is greatly reduced (basically disappears), allowing the cable to continue to work in the 3.3GHz-3.7GHz stage after exceeding the cutoff frequency.

[0067] It should be noted that Figure 6 and Figure 7 In the VSWR test diagram shown, the horizontal axis represents the test frequency, the vertical axis represents the VSWR test value, the "Trl" in the diagram represents the "test window", the "S11" represents the "instrument test port", the "SWR" represents the "voltage standing wave ratio", the "Ref" represents the "bottom line value", the "Start" represents the "starting frequency", the "Stop" represents the "stop frequency", and the "Cor" represents the "calibrated state".

[0068] It should be noted that the compression ratio of the inner conductor 1 indicates the degree of dimensional change of the conductor material after compression or extrusion during the production process. Specifically, it usually refers to the ratio of the outer diameter of the conductor after corrugation to the original smooth conductor diameter.

[0069] It should be noted that the selection of relevant values ​​such as corrugation pitch and depth in super-cutoff frequency RF coaxial cables should comply with the relevant design standards in the industry standards.

[0070] It should be noted that the “axial direction” described in this application refers to Figure 1 The direction indicated by arrow a is radial and perpendicular to the axial direction.

[0071] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components or combinations thereof.

[0072] It should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0074] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0075] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A super cut-off frequency radio frequency coaxial cable, characterized in that: The cable comprises, from the inside to the outside, an inner conductor (1), an insulating layer (2), an outer conductor (3) and a sheath layer (4), wherein: The inner conductor (1) is a spiral corrugated tube with a threaded structure, the tooth shape of the threaded structure is a square wave with rounded chamfers, and, The corrugation pitch of the inner conductor (1) changes in a periodic fluctuation along the axial direction, or the compression ratio of the inner conductor (1) changes in a periodic fluctuation along the axial direction.

2. The super cut-off frequency radio frequency coaxial cable according to claim 1, characterized in that: The thread structure comprises a crest section (5) and a root section (6), wherein: The axial length of the tooth peak section (5) is greater than the axial length of the tooth bottom section (6); The sum of the axial length of the tooth peak section (5) and the axial length of the tooth bottom section (6) is equal to the corrugation pitch of the inner conductor (1).

3. The super cut-off frequency radio frequency coaxial cable according to claim 2, characterized in that: The tooth bottom section (6) and the tooth peak section (5) satisfy the following relationship: Wherein, X represents the axial length of the tooth base segment (6), and Y represents the axial length of the tooth peak segment (5).

4. The super cut-off frequency radio frequency coaxial cable according to claim 2, characterized in that: The side wall surfaces of the tooth bottom section (6) and the tooth peak section (5) include a tooth bottom chamfered section (7), a linear flattened section (8) and a tooth peak chamfered section (9), and the tooth bottom chamfered section (7), the linear flattened section (8) and the tooth peak chamfered section (9) are smoothly connected in sequence from the inside to the outside along the radial direction of the inner conductor (1).

5. The super cut-off frequency radio frequency coaxial cable according to claim 4, characterized in that: The thread depth of the thread structure satisfies the following relationship: Wherein, D represents the tooth depth, R1 represents the radial length of the tooth bottom chamfered section (7), R2 represents the radial length of the tooth peak chamfered section (9), and L represents the radial length of the linear flattened section (8).

6. The super cut-off frequency radio frequency coaxial cable according to claim 1, characterized in that: The corrugation pitch of the inner conductor (1) satisfies the following relationship: Wherein, P represents the corrugation pitch of the inner conductor (1), A is a fixed constant, is the phase angle parameter, The value range of is 0~2π, It is a pre-set standard corrugation pitch.

7. The super cut-off frequency radio frequency coaxial cable according to any one of claims 1 to 6, characterized in that: In the same periodic fluctuation change, the corrugation pitch / compression ratio of the inner conductor (1) first changes from large to small and then changes from small to large, or the corrugation pitch / compression ratio of the inner conductor (1) first changes from small to large and then changes from large to small.

8. The super cut-off frequency radio frequency coaxial cable according to any one of claims 1 to 6, characterized in that: The inner conductor (1) is a single-helix spiral corrugated tube, or the inner conductor (1) is a double-helix spiral corrugated tube.

9. The super cut-off frequency radio frequency coaxial cable according to any one of claims 1 to 6, characterized in that: The inner conductor (1) whose corrugation pitch fluctuates periodically along the axial direction is manufactured in the following manner: The inner conductor smooth strip is rolled and welded to obtain a smooth inner conductor round tube; A smooth inner conductor round tube is pulled at a pulling speed that fluctuates periodically, and a concentric corrugating blade with a circular arc angle is used to corrugate the smooth inner conductor round tube to obtain an inner conductor (1).

10. The super cut-off frequency radio frequency coaxial cable according to any one of claims 1 to 6, characterized in that: The RF coaxial cable is a RF coaxial cable with a specification of 7 / 8 inches or above.

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