A super cut-off frequency radio frequency coaxial cable

Abstract

This application belongs to the field of wireless communication technology and relates to a radio frequency coaxial cable with a super cut-off frequency. The coaxial cable sequentially includes an inner conductor, an insulating layer, an outer conductor, and a sheath layer from the inside to the outside. By designing the inner conductor as a spiral corrugated tube and its tooth shape as a square waveform with round chamfers, the inductance can be increased, the phase of high-frequency signals can be delayed, and the excitation of higher-order modes can be effectively weakened. The radio frequency coaxial cable of this application can continue to work after the super cut-off frequency, provide a relatively wide operating frequency under large-size conditions, and meet the requirements of low loss, large coverage, and high frequency in mobile communication networking. The standing wave diagram of the product of this application shows that the interference peak value at 3.3 GHz - 3.7 GHz is greatly reduced or even basically disappears, enabling the radio frequency coaxial cable to continue to work in the 3.3 GHz - 3.7 GHz stage after the super cut-off frequency.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology and relates to a radio frequency coaxial cable with a super cut-off frequency. Background Art

[0002] Radio frequency coaxial cables can be used for signal transmission in mobile communication bands such as meter waves, decimeter waves, and centimeter waves. They are an important part of the antenna system and are mostly used for radio frequency signal transmission between mobile base stations and antennas.

[0003] In the related art, the operating frequency of the cable is greatly affected by the cut-off frequency of the cable. After the cable exceeds a certain size, affected by high-order harmonics, the standing wave and transmission loss performance of the radio frequency coaxial cable deteriorate severely after exceeding the cut-off frequency, making it difficult to be used after the cut-off frequency and resulting in a relatively low operating frequency of the cable. For example, for a traditional coaxial cable of a certain specification, its cut-off frequency is about 2.7 GHz, which still cannot meet the requirements of high operating frequencies in mobile communication. Therefore, when forming a mobile communication network, it is often necessary to choose a small-sized coaxial cable that can provide a higher frequency. However, compared with large-sized coaxial cables, small-sized coaxial cables usually have a greater transmission loss, which may lead to a significant reduction in the coverage range of mobile communication devices. Summary of the Invention

[0004] Aiming at the defects or improvement requirements of the prior art, this application provides a radio frequency coaxial cable with a super cut-off frequency. This cable can continue to work normally after the cut-off frequency, can provide a relatively high operating frequency under large-sized conditions, and can meet the requirements of low loss, large coverage range, and high frequency in mobile communication network formation.

[0005] A radio frequency coaxial cable with a super cut-off frequency provided by this application includes, from the inside to the outside in sequence, an inner conductor, an insulating layer, an outer conductor, and a sheath layer, where:

[0006] The inner conductor is a spiral corrugated tube with a threaded structure, and the tooth shape of the threaded structure presents a square wave shape with a round chamfer, and

[0007] The corrugation pitch of the inner conductor changes periodically along the axial direction, or the compression ratio of the inner conductor changes periodically along the axial direction.

[0008] Through the above technical solution conceived in this application, compared with the prior art, in this design, by designing the inner conductor as a spiral corrugated tube and its tooth shape as a square wave shape with round chamfers, the compression ratio of the inner conductor can be effectively increased, the inductance of the inner conductor can be enhanced, and the phase of the high-frequency signal can be delayed, thereby effectively weakening the excitation of the high-order mode. For the cable based on this tooth shape design, the current direction in the cable will be basically perpendicular to the axial direction of the cable or parallel to the axial direction 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 more clearly controllable.

[0009] 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 at each frequency point after the supercutoff frequency are not superposed periodically, and the reflections at each frequency point are regularly disrupted, thereby effectively weakening the excitation of the high-order mode and suppressing the interference of the high-order harmonics on the coaxial cable. This broadens the operating frequency of the cable, enables the cable to continue to work effectively after exceeding the cutoff frequency, and thus enables the cable to provide a relatively wide operating frequency under large-size conditions, meeting the requirements of low loss, large coverage, and high frequency in mobile communication networking.

[0010] As a further preference, the thread structure includes a tooth crest section and a tooth root section, where:

[0011] The axial length of the tooth crest section is greater than the axial length of the tooth root section;

[0012] The sum of the axial length of the tooth crest section and the axial length of the tooth root section is equal to the corrugation pitch of the inner conductor.

[0013] As a further preference, the tooth root section and the tooth crest section satisfy the following relationship:

[0014]

[0015] Wherein, X represents the axial length of the tooth root section, and Y represents the axial length of the tooth crest section.

[0016] As a further preference, the side wall surfaces of the tooth root section and the tooth crest section include a tooth root chamfer section, a linear flat section, and a tooth crest chamfer section, and the tooth root chamfer section, the linear flat section, and the tooth crest chamfer section are smoothly connected in sequence from the inside to the outside along the radial direction of the inner conductor.

[0017] As a further preference, the tooth depth of the thread structure satisfies the following relationship:

[0018]

[0019]

[0020]

[0021] Among them, D represents the tooth depth, and R 1 represents the radial length of the tooth root chamfer section, and R 2 represents the radial length of the tooth crest chamfer section, and L represents the radial length of the linear flat section.

[0022] As a further preference, the corrugation pitch of the inner conductor satisfies the following relational expression:

[0023]

[0024] Among them, P represents the corrugation pitch of the inner conductor, A is a fixed constant, is the phase angle parameter, the value range of is 0 to 2π, is the preset standard corrugation pitch.

[0025] As a further preference, in the same periodic fluctuation change, the corrugation pitch / compression ratio of the inner conductor first decreases from large to small, and then increases from small to large, or, the corrugation pitch / compression ratio of the inner conductor first increases from small to large, and then decreases from large to small.

[0026] As a further preference, the inner conductor is a single-spiral helical corrugated tube, or, the inner conductor is a double-spiral helical corrugated tube.

[0027] As a further preference, the inner conductor with a corrugation pitch that fluctuates periodically along the axial direction is obtained by the following method:

[0028] The smooth strip of the inner conductor is coiled and welded to obtain a smooth inner conductor circular tube;

[0029] The smooth inner conductor circular tube is pulled at a periodically fluctuating traction speed, and at the same time, the smooth inner conductor circular tube is corrugated with a concentric corrugating blade with an arc angle to obtain the inner conductor.

[0030] As a further preference, this radio frequency coaxial cable is a radio frequency coaxial cable with a specification of 7 / 8 inch and above.

[0031] Generally speaking, compared with the prior art through the above technical solutions conceived by this application, the following technical advantages are mainly possessed:

[0032] 1. The spiral structure of the inner conductor of the cable in this application is set as a square waveform, and the corrugation pitch of the inner conductor varies periodically along the axial direction (or the compression ratio of the inner conductor varies periodically along the axial direction), so that the reflections at each frequency point after the super cutoff frequency of the cable are not periodically superimposed, and the reflections at each frequency point are regularly disrupted, thereby effectively weakening the excitation of the higher-order modes, suppressing the interference of the higher-order harmonics to the coaxial cable, and broadening the working frequency of the cable. This enables the cable to continue to work effectively after exceeding the cutoff frequency, and enables the cable to provide a wider working frequency with a larger specification size to meet the requirements of low loss, large coverage range, and high frequency in mobile communication networking.

[0033] 2. By setting the ratio of the axial length of the root section of the inner conductor to the axial length of the peak section within to it can ensure the optimization of the performance of the cable under complex constraint conditions such as electrical performance and mechanical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of a single-spiral form of super cutoff frequency radio frequency coaxial cable provided by an embodiment of this application;

[0035] Figure 2 is a schematic structural diagram of a double-spiral form of super cutoff frequency radio frequency coaxial cable provided by an embodiment of this application;

[0036] Figure 3 is a schematic diagram of a square-wave tooth shape showing the thread structure;

[0037] Figure 4 is a distribution diagram of the root chamfer section, linear flat section, and peak chamfer section provided by an embodiment of this application;

[0038] Figure 5 is a manufacturing process flow chart of an inner conductor provided by an embodiment of this application;

[0039] Figure 6 is a voltage standing wave ratio test diagram of an existing radio frequency coaxial cable provided by an embodiment of this application;

[0040] Figure 7 is a voltage standing wave ratio test diagram of a super cutoff frequency radio frequency coaxial cable provided by an embodiment of this application.

[0041] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0042] 1. Inner conductor; 2. Insulation layer; 3. Outer conductor; 4. Sheath layer; 5. Peak section; 6. Root section; 7. Root chamfer section; 8. Linear flat section; 9. Peak chamfer section. Detailed implementation mode

[0043] In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below with reference to 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.

[0044] The following combines the attached Figures 1-7 The present application is further described in detail.

[0045] The embodiment of the present application discloses a super cut-off frequency radio frequency coaxial cable. Refer to Figures 1-2 , the super cut-off frequency radio frequency coaxial cable sequentially includes an inner conductor 1, an insulating layer 2, an outer conductor 3 and a sheath layer 4 from inside to outside. Among them, the inner conductor 1 is a spiral corrugated tube with a threaded structure, and the tooth shape of the threaded structure is a square wave shape with a round chamfer. In addition, the corrugation pitch of the inner conductor 1 changes periodically along the axial direction, or the compression ratio of the inner conductor 1 changes periodically along the axial direction.

[0046] Under this design, by designing the inner conductor 1 as a spiral corrugated tube and its tooth shape as a square wave shape with a round chamfer, 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; for the cable based on this tooth shape design, the current direction in the cable will be basically perpendicular to the axial direction of the cable or basically parallel to the axial direction of the cable, which makes the current transmission direction of the inner conductor 1 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 more clearly controllable.

[0047] In addition, because the corrugation pitch of the inner conductor 1 changes periodically along the axial direction (or the compression ratio of the inner conductor 1 changes periodically along the axial direction), the reflections of each frequency point after the super cut-off 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 the high-order harmonics on the coaxial cable, enhancing the inductance, so that the radio frequency coaxial cable under this structural design can continue to work effectively after exceeding the cut-off frequency, and the working frequency is expanded. Compared with the traditional radio frequency coaxial cable, the present radio frequency coaxial cable can provide a wider working frequency under the same specification size conditions to meet the requirements of low loss, large coverage range and high frequency in mobile communication networking. In particular, this design is particularly suitable for application to radio frequency coaxial cables with a specification of 7 / 8 inches and above. That is, preferably, the present radio frequency coaxial cable is a radio frequency coaxial cable with a specification of 7 / 8 inches and above.

[0048] Furthermore, as Figure 3As shown, in some embodiments, the thread structure of the inner conductor 1 is obtained by a rolling process. Among them, the thread structure includes a tooth crest section 5 and a tooth root section 6, and the tooth crest section 5 and the tooth root section 6 are arranged alternately along the axial direction of the inner conductor 1.

[0049] Preferably, the axial length of the tooth crest section 5 is greater than the axial length of the tooth root section 6, and the sum of the axial lengths of the tooth crest section 5 and the tooth root section 6 is equal to the rolling pitch of the inner conductor 1.

[0050] Furthermore, as Figure 4 shown, in some embodiments, the side wall surfaces of the tooth root section 6 and the tooth crest section 5 include a tooth root chamfer section 7, a linear flat section 8, and a tooth crest chamfer section 9, and the tooth root chamfer section 7, the linear flat section 8, and the tooth crest chamfer section 9 are smoothly connected in sequence from the inside to the outside along the radial direction of the inner conductor 1.

[0051] Furthermore, in some embodiments, in the same periodic fluctuation change, the rolling pitch / compression ratio of the inner conductor 1 first decreases from large to small, and then increases from small to large. In some other embodiments, in the same periodic fluctuation change, the rolling pitch / compression ratio of the inner conductor 1 first increases from small to large, and then decreases from large to small.

[0052] Under this design, by regularly controlling the rolling 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.

[0053] It should be clear that when designing the rolling pitch of the inner conductor 1 to change periodically along the axial direction, since the sum of the axial lengths of the tooth root section 6 and the tooth crest section 5 is equal to the rolling pitch, at this time, the axial lengths of the tooth root section 6 and the tooth crest section 5 in the inner conductor 1 will also change accordingly with the change of the rolling pitch. That is, when the rolling pitch of the inner conductor 1 changes periodically along the axial direction, it is preferably to select the ratio of the axial length of the tooth root section 6 to the axial length of the tooth crest section 5 as a fixed ratio value, and then calculate the axial lengths of the tooth root section 6 and the tooth crest section 5 based on this fixed ratio value and the actual value of the rolling pitch.

[0054] It can be clear that when designing the compression ratio of the inner conductor 1 to change periodically along the axial direction, it is preferably to set the depth of the inner conductor 1 to change periodically along the axial direction to achieve the purpose of the periodic fluctuation change of the compression ratio of the inner conductor 1.

[0055] Furthermore, in some specific embodiments, the axial lengths of the tooth crest section 5 and the tooth root section 6 are set to satisfy the following relationship:

[0056]

[0057]

[0058] Wherein, X represents the axial length of the tooth root section 6, Y represents the axial length of the tooth peak section 5, and P represents the pitch of the corrugations of the inner conductor 1.

[0059] It should be noted that taking the ratio of the axial length of the tooth root section 6 to the axial length of the tooth peak section 5 within the range of to is a better design result considering various factors.

[0060] Specifically, in a radio frequency coaxial cable, the tooth peak section 5 of the inner conductor 1 will serve as the main current-carrying area, and its length ratio needs to dominate the electric field distribution, which makes the ratio control of the tooth peak section 5 and the tooth root section 6 have a greater impact on the electrical performance of the cable. For the inner conductor, since 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 the high-frequency resistance, and reduce signal attenuation.

[0061] In addition, in the cable, a longer tooth peak section 5 (dominant) can provide better structural rigidity for the inner conductor 1 and enhance the ability of the inner conductor 1 to resist external extrusion; at the same time, combined with the small round chamfer design in the thread structure, the inner conductor 1 exerts less pressure on the insulating layer 2 and is not prone to generating indentations.

[0062] For the tooth root section 6, if the tooth root section 6 is too short, it will cause local distortion of the electric field. If the tooth root section 6 is too long, it may weaken the regulation effect of the thread on the field distribution. And a moderate tooth root section 6 can better serve as a buffer zone to disperse the bending stress, avoiding stress concentration at a single position and resulting in metal fatigue fracture, which can make the cable have better flexibility and improve the bending fatigue life of the cable.

[0063] In addition, it is found in actual production that since the inner conductor 1 needs to use a corrugating tool to make the thread structure, a tooth root section 6 that is too short is often difficult to process; moreover, a tooth root section 6 that is too short will increase the local stress of the corrugating tool, accelerate tool wear, and, in addition, a tooth root section 6 that is too short is prone to burrs during manufacturing, which makes the control of the length of the tooth root section 6 have a greater impact on the feasibility of the corrugating process and the manufacturing cost.

[0064] In addition, considering that the axial lengths of the tooth root section 6 and the tooth peak section 5 are related to the pitch of the corrugations of the inner conductor 1, by taking the ratio of the axial length of the tooth root section 6 to the axial length of the tooth peak section 5 within the range of ~ , it can ensure that the axial lengths of the tooth root section 6 and the tooth peak section 5 are relatively appropriate, enabling the cable to have relatively superior performance under complex constraint conditions.

[0065] Furthermore, in some embodiments, the tooth depth of the thread structure satisfies the following relationship:

[0066]

[0067]

[0068]

[0069] Among them, D represents the current tooth depth, and R 1 represents the radial length of the bottom chamfer section 7 of the tooth, and R 2 represents the radial length of the peak chamfer section 9 of the tooth, and L represents the radial length of the linear flat section 8; preferably, both the bottom chamfer section 7 and the peak chamfer section 9 are 90-degree circular chamfers. Among them, the radial lengths of the bottom chamfer section 7 and the peak chamfer section 9 are the circular chamfer radii. Preferably, = .

[0070] Under this design, by controlling the size of the circular chamfer of the thread structure within a specific range, the inner conductor 1 is not easily damaged to the insulating layer 2, and the circular chamfer of the thread structure has a very small influence on the current direction in the cable.

[0071] Specifically, in some embodiments, when the thread pitch of the inner conductor 1 fluctuates periodically along the axial direction, the thread pitch of the inner conductor 1 satisfies the following relational expression:

[0072]

[0073] Among them, P represents the thread 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 change of the thread pitch; is the preset standard thread pitch, and this standard thread pitch can be selected based on existing specifications and standards, such as being selected based on the relevant design standard regulations in the industry standard YD / T1092.

[0074] Preferably, A is preferably 0.03. Generally speaking, it is periodically accumulated in increments of ΔΦ = 5°~10° along the axial direction of the cable (where 0~360° corresponds to a complete waveform cycle), and one cycle is completed every 20 meters~50 meters along the axial length of the cable. Preferably, in one cycle, it is periodically accumulated and taken with 5 degrees as the change amount (for example, = , n = 0 degrees, 1 degree, 2 degrees, 3 degrees, etc.), and, along the axial direction of the cable, the phase angle is accumulated by 5 degrees every 0.5 meters.

[0075] Under this design, the corrugation pitch of the inner conductor 1 is controlled by the variation law of the cosine function, which can prevent the reflection of other frequency points due to the multiple-frequency superposition characteristics caused by linear variation, and the process implementation is relatively simple.

[0076] Further, in some embodiments, the inner conductor 1 is a single-spiral corrugated tube. In some other embodiments, the inner conductor 1 can also be a double-spiral corrugated tube. Compared with the single-thread design, the inner conductor 1 with a double-spiral design has better cable bending performance and a larger compression ratio, with stronger inductance and better electrical performance.

[0077] Further, as Figure 5 shown, in some embodiments, an inner conductor 1 with a corrugation pitch that varies periodically along the axial direction is obtained by the following steps:

[0078] S1: The smooth strip of the inner conductor is wound into a circle and welded to obtain a smooth inner conductor circular tube.

[0079] Generally, first, the smooth strip of the inner conductor is fed, then the smooth strip of the conductor is wound into a circle, and then the wound smooth strip of the inner conductor is pulled to the welding station and welded by a welding device to obtain a smooth inner conductor circular tube.

[0080] S2: The smooth inner conductor circular tube is pulled by a traction device at a periodically fluctuating traction speed, and at the same time, the smooth inner conductor circular tube is corrugated by a concentric corrugating blade with an arc angle 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 varies periodically along the axial direction, and then the inner conductor 1 is taken up (wound).

[0081] In this step, preferably, the real-time linear speed of the traction of the smooth inner conductor circular tube is collected by a speed encoder, and the inner conductor 1 is pulled by a variable-frequency motor according to the set rotation speed variation law to realize the variation of the corrugation pitch according to the established variation law; at the same time, a spiral thread structure with a square-tooth cross-section is rolled out by a concentric small-arc-angle corrugating blade.

[0082] For easy understanding, Figure 6 shows a standing wave ratio test diagram of a traditional 1 inch (i.e., ) specification radio frequency coaxial cable (selected from the 1 inch standard specification cable specified in the industry standard YD / T1092). As can be seen from Figure 6 , obvious interference peaks appear in the 3.3 GHz - 3.7 GHz range after the super cutoff frequency for this traditional cable (i.e., the existing cable).

[0083] Figure 7 shows a 1 inch (i.e., a radio frequency coaxial cable, which is different from the above-mentioned traditional radio frequency 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 wave shape with a round chamfer, 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 through the periodic fluctuation of the depth).

[0084] The depth of the inner conductor 1 takes values of 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm; and the depth changes periodically in the order of 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.3mm, 2.2mm, 2.1mm, 2.0mm.

[0085] Among them, the pitch of the corrugation of the inner conductor 1 is 10.2mm, and the ratio of the axial length of the tooth root section 6 to the axial length of the tooth peak section 5 is: ; the axial length of the tooth root section 6 is 3.06mm, and the axial length of the tooth peak section 5 is 7.14mm.

[0086] Among them, the round chamfer of the threaded 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 values are = = , when the depth is 2.0mm, the radial length of the linear flat section 8 is 1.5mm, the radius of the round chamfer of the tooth root chamfer section 7 is 0.25mm, and the radius of the round chamfer of the tooth peak chamfer section 9 is 0.25mm.

[0087] The standing wave of the super cutoff frequency radio frequency coaxial cable Figure 3 .3GHz - 3.7GHz interference peak is greatly reduced (basically disappears), enabling the cable to continue to work in the 3.3GHz - 3.7GHz stage after the super cutoff frequency.

[0088] It should be noted that Figure 6 and Figure 7 in the voltage standing wave ratio test diagrams shown, the abscissa represents the test frequency, the ordinate represents the voltage standing wave ratio test value, "Trl" in the figure represents "test window", "S11" represents "instrument test port", "SWR" represents "voltage standing wave ratio", "Ref" represents "bottom line value", "Start" represents "starting frequency", "Stop" represents "ending frequency", and "Cor" represents "calibrated state".

[0089] It should be noted that the compression ratio of the inner conductor 1 indicates the degree of dimensional change of the conductor material after being compressed or extruded during the production process. Specifically, it usually refers to the ratio of the outer diameter of the corrugated conductor to the diameter of the original smooth conductor.

[0090] It should be noted that the selection of values such as the corrugation pitch and depth in the super cutoff frequency radio frequency coaxial cable should comply with the relevant design standard regulations in the industry standard.

[0091] It should be noted that the "axial direction" described in this application is Figure 1 the direction indicated by the arrow a in. The radial direction is perpendicular to the axial direction.

[0092] It should be understood that expressions such as "including" 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 "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, constituent elements, components, or a combination thereof.

[0093] 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.

[0094] 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, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, the meaning of "a plurality of" is two or more, unless otherwise specifically defined.

[0095] In this application, unless otherwise clearly stipulated and defined, terms such as "installed", "connected", "linked", "fixed", etc. shall 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 components. 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.

[0096] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the protection scope of this 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) fluctuates periodically along the axial direction, or the compression ratio of the inner conductor (1) fluctuates periodically along the axial direction, wherein the compression ratio is the ratio of the outer diameter of the conductor after corrugation to the diameter of the original smooth conductor.

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 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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