CN114696053A - Circular waveguide transmission line for millimeter wave and method for manufacturing the same - Google Patents

Abstract

The invention discloses a circular waveguide transmission line for millimeter waves and a manufacturing method thereof, wherein the circular waveguide transmission line comprises a plastic rod, an outer conductor, a metal ridge line and a sheath layer; the plastic rod sequentially comprises a core layer and an outer skin layer from inside to outside, and the outer skin layer is coated on the core layer; the outer conductor is coated on the plastic rod; the metal ridge line is connected with the outer conductor and is lapped on the plastic rod; the sheath layer is coated on the outer conductor. By utilizing the technical scheme of the invention, the metal ridge line is introduced into the waveguide structure, the problem of polarization deflection of the circular waveguide can be effectively improved, the practicability of remote transmission is improved, and meanwhile, compared with the traditional all-metal copper (aluminum) hollow pipe leaky cable waveguide, the circular waveguide transmission line for the millimeter wave using the plastic rod as the inner liner layer has better elasticity and recoverability, and can avoid damage in the transportation or construction and arrangement process.

Description

Circular waveguide transmission line for millimeter wave and method for manufacturing the same

Technical Field

The invention relates to the technical field of communication transmission, in particular to a circular waveguide transmission line for millimeter waves.

Background

With the continuous development of modern communication technology, spectrum resources are in more and more shortage, and millimeter wave bands have huge spectrum resource development space, so how to develop and utilize millimeter wave spectrum resources originally applied to satellites and radar military systems becomes the key point of the fifth-generation mobile communication technology. The problem of transmission of millimeter wave signals between devices faces improvement and replacement due to the sharp increase of attenuation of the traditional coaxial cable in millimeter wave band.

The circular waveguide is a cylindrical waveguide with a circular section, has the characteristics of low loss and dual polarization, is commonly used in an antenna feeder line, can also be used as a long-distance transmission line, and is widely used as a microwave resonant cavity. Circular waveguides as communication transmission lines for transmitting millimeter wave electromagnetic signals have many advantages: the transmission power is higher (the cross section area is the largest due to the circle) and the transmission attenuation is reduced under the same cross section perimeter. And the rectangular waveguide tube can be relatively simply and easily transported in a tray, constructed and laid, and the like. However, the requirements on the process precision and the product consistency of the waveguide tube for realizing millimeter wave signal transmission by the circular waveguide tube are strict, and in order to realize wider application of the circular waveguide tube, the structure and the production process of the circular waveguide tube need to be improved.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention provides a circular waveguide transmission line with stable waveguide structure and electrical performance and a method for manufacturing the same.

In order to solve the technical problems, the invention firstly provides the following technical scheme: a circular waveguide transmission line for millimeter waves, comprising:

the plastic rod sequentially comprises a core layer and an outer skin layer from inside to outside, and the outer skin layer is coated on the core layer;

an outer conductor wrapped around the plastic rod;

the metal ridge line is connected with the outer conductor, is lapped on the plastic rod and is continuously arranged along the length direction of the plastic rod;

the sheath layer is coated on the outer conductor.

Through adopting above-mentioned technical scheme, introduce the waveguide structure with the metal ridge line, can effectively improve the polarization problem of deflecting, improve remote transmission's practicality, simultaneously, regard the inner liner of the circular waveguide transmission line that the millimeter wave was used with the plastic pole, can prevent that external moisture from invading in the transmission line to influence the electric property of transmission line. Meanwhile, compared with the traditional all-metal copper (aluminum) hollow pipe leaky cable waveguide, the round waveguide transmission line for the millimeter waves with the plastic rod as the lining layer has better elasticity and recoverability, and can avoid damage in the transportation or construction and arrangement process.

In an embodiment of the invention, the outer conductor is a single-layer copper-plastic composite film, which includes a copper layer and a plastic layer, and the copper layer is connected with the plastic layer.

In an embodiment of the invention, the thickness of the copper layer ranges from 0.1mm to 0.2mm, and the thickness of the plastic layer ranges from 0.08mm to 0.2 mm.

By adopting the technical scheme, the copper-plastic composite film is used as the outer conductor of the circular waveguide, so that the performance of the waveguide tube can be improved, and meanwhile, the size selection of the copper layer and the plastic layer can better meet the communication requirement without influencing other performances of the circular waveguide transmission line.

In an embodiment of the invention, the width of the metal ridge line is 0.5mm to 3 mm.

By adopting the technical scheme, the problem of polarization generated in the application process of the circular waveguide can be better improved, and other performances of the circular waveguide cannot be influenced.

In an embodiment of the present invention, the core layer is a foamed polyolefin material.

In an embodiment of the present invention, the outer skin layer is an unfoamed polyolefin material.

In an embodiment of the present invention, the dielectric constant of the material used for the core layer and the skin layer is less than 2.25F/m.

By adopting the technical scheme, on one hand, the transmission line can be prevented from being invaded by external moisture in long-term work, so that the transmission performance of the circular waveguide transmission line for the millimeter waves is influenced; on the other hand, the core layer and the outer skin layer have low relative dielectric constants, so that the influence of the filler on high-frequency signal transmission can be reduced.

In one embodiment of the present invention, the ellipticity of the plastic rod is 0.001, and the straightness of the plastic rod is not greater than 3mm per meter.

By adopting the technical scheme, the signal transmission performance of the circular waveguide transmission line can be improved.

In an embodiment of the invention, the material of the sheath layer is polyolefin, flame retardant polyolefin or polyvinyl chloride.

By adopting the technical scheme, the circular waveguide can be protected from mechanical damage, and meanwhile, the flame retardant property is achieved when the requirement is met.

In order to solve the above technical problem, the present invention further provides a method for manufacturing a circular waveguide transmission line for millimeter waves, comprising the steps of:

s1: the method comprises the following steps of extruding and molding a plastic rod by using a double-layer extruding machine to obtain the plastic rod, wherein the obtained plastic rod comprises a core layer and an outer skin layer, the core layer is subjected to physical foaming treatment in a nitrogen or carbon dioxide gas injection mode in the extruding process, and the outer skin layer is not subjected to foaming treatment and uniformly wraps the core layer;

s2: coating a chemical agent on the outer side of the plastic rod, and adhering an outer conductor on the outer surface of the plastic rod in a longitudinal wrapping mode through the chemical agent, wherein in the adhering process, two edges of the outer conductor are overlapped and overlapped on the plastic rod to form a metal ridge line;

s3: through a negative pressure air exhaust process, the molten sheath layer material can be tightly coated on the outer conductor after passing through the plastic extruding machine, so that the outer conductor is tightened and fixed on the plastic rod.

By adopting the technical scheme, the two edges of the outer conductor are overlapped and lapped on the plastic rod to form the metal ridge line, so that the problem of polarization deflection of the circular waveguide transmission line in practical application is solved, the realizability of process production is greatly improved, continuous and large-length industrial mass production can be realized, and the consistency and stability of products are improved.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a circular waveguide transmission line for millimeter waves according to the present invention;

fig. 2 is a schematic cross-sectional view of a circular waveguide transmission line for millimeter waves according to the present invention;

FIG. 3 is a schematic structural diagram of a single-layer copper-plastic composite film provided by the present invention;

fig. 4 is a flowchart of a method for manufacturing a circular waveguide transmission line for millimeter waves according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

As shown in fig. 1 to 3, the present invention provides a circular waveguide transmission line for millimeter waves, which is sequentially provided with a plastic rod 1, an outer conductor 2, a metal ridge line 3 and a sheath layer 4 from inside to outside. The plastic rod 1 sequentially comprises a core layer 11 and an outer skin layer 12 from inside to outside, and the outer skin layer 12 is coated on the core layer 11. The outer conductor 2 is clad on the plastic rod 1, that is, the outer conductor 2 is clad on the outer skin layer. The metal ridge line 3 is connected with the outer conductor 2, the metal ridge line 3 is lapped on the plastic rod 1, and the metal ridge line 3 is continuously arranged along the length direction of the plastic rod 1. The sheath layer 4 is coated on the outer conductor 2. In the present embodiment, the outer conductor 2 is wrapped around the plastic rod 1 by means of an integral longitudinal wrapping. In the embodiment, the outer conductor 2 is a single-layer copper-plastic composite film, which includes a copper layer 21 and a plastic layer 22, the copper layer 21 is a copper tape, such as TU2 type oxygen-free copper, the thickness range of the copper layer 21 is 0.1mm to 0.2mm, the plastic layer 22 can be made of ethylene acrylic acid copolymer or ethylene methacrylic acid copolymer, and the thickness range of the plastic layer 22 is 0.08mm to 0.2 mm. The thickness of the copper-plastic composite film is selected to meet the communication requirement and not to influence the performance of the circular waveguide transmission line for millimeter waves. Further, according to a skin depth calculation formula of the high-frequency electromagnetic field transmitted in the metal conductor:

wherein: δ is the skin depth, ω is the angular frequency, μ is the permeability, ρ is the resistivity, and can be calculated as:

therefore, the thickness of the copper layer 21 of the copper-plastic composite film can meet the communication requirement under high frequency, can be used as the outer conductor 2 of the circular waveguide transmission line for millimeter waves, and does not influence the high-frequency electrical performance of the circular waveguide transmission line for millimeter waves. Introduce the waveguide structure with metal ridge 3, and metal ridge 3 sets up in succession along 1 length direction of plastic pole, can effectively improve the polarization problem of deflecting, improves remote transmission's practicality, simultaneously, regards the inner liner of the circular waveguide transmission line that the millimeter wave was used as the plastic pole, can prevent that external moisture from invading in the transmission line to influence the electrical property of transmission line. Meanwhile, compared with the traditional all-metal copper (aluminum) hollow pipe leaky cable waveguide, the round waveguide transmission line for the millimeter waves with the plastic rod as the lining layer has better elasticity and recoverability, and can avoid damage in the transportation or construction and arrangement process.

As shown in fig. 1 to 3, in the present embodiment, the plastic rod 1 has a double-layer structure, which includes a core layer 11 and an outer skin layer 12 from inside to outside, and the core layer 11 is a physically foamed polyolefin material with a low density or other materials with excellent dielectric constant. The outer skin layer 12 is an unfoamed low-density polyolefin material or other material with the same or similar dielectric constant performance with the core layer material, and the dielectric constant of the core layer 11 and the material used by the outer skin layer 12 is less than 2.25F/m. In the embodiment, the plastic rod is used as the waveguide lining layer, so that the structural stability and the electrical performance stability of the circular waveguide transmission line for millimeter waves can be improved. Meanwhile, on one hand, moisture in the surrounding environment can be prevented from gradually invading the transmission line in the long-term operation process, so that the electrical performance of the circular waveguide is influenced, and on the other hand, the plastic material has elasticity and recoverability, so that the damage in the transportation or construction and arrangement process can be prevented, and the stability of the product structure is further improved. In this embodiment, the size of the outer diameter of the plastic rod 1 is linear with the cut-off wavelength of the transmission signal, and the outer diameter of the plastic rod 1 can be determined according to the communication working frequency and the cut-off frequency of the circular waveguideIs selected according to the formula. For example, the transmission of high frequency signals in circular waveguides is limited by the cut-off wavelength, i.e. when the main transmission mode in circular waveguides is TE₁₁Time sum TM₀₁The diameter of the circular waveguide can be derived according to the following formula of lambdac 3.412 x D/2 and lambdac 2.61 x D/2, wherein lambdac is the cut-off wavelength; d is the diameter of the circular waveguide, that is, the outer diameter of the plastic rod 1 in this embodiment, and the outer diameter of the plastic rod 1 should be controlled to have a deviation of less than ± 0.05mm, an ellipticity of 0.001, and a straightness of not more than 3mm per meter. Of course, in practical applications, for a circular waveguide, the waveguide signal is transmitted and the equivalent dielectric constant ε of the circular waveguide needs to be distinguished_gGreater than or equal to and less than 1, and epsilon_gDetermined by parameters such as the dielectric constant of the core layer 11, the waveguide operating frequency, and the waveguide cutoff wavelength. Therefore, to determine the outer diameter dimension of the circular waveguide, the equivalent dielectric constant of the plastic rod inner core layer 11, the operating radiation mode of the waveguide, the operating frequency, the waveguide cutoff wavelength, the size and period of the slot for the signal, and the like are considered. In the present embodiment, the sheath layer 4 is polyolefin, but is not limited thereto, and may be flame retardant polyolefin, polyvinyl fluoride, or the like, as long as it can protect the cable from mechanical damage and has a flame retardant function when necessary.

As shown in fig. 1 to 3, in the present embodiment, the metal ridge line 3 is formed by overlapping and overlapping both edges of the outer conductor 2 on the plastic rod, the shape of the metal ridge line 3 may be rectangular, circular, etc., the maximum size of the metal ridge line 3 may vary within a range smaller than the radius of the circular waveguide, and in the present embodiment, the width of the metal ridge line 3 ranges from 0.5mm to 3 mm. When no metal ridge 3 is present in the circular waveguide, the boundary condition of the circular waveguide is rotationally symmetric, TE₁₁The field distribution of the wave type electric field when the polarization plane deflects by any angle is the solution of Maxwell equation set under the condition of meeting the same boundary condition. The electric field inside the waveguide is increased along with the increase of the width of the metal ridge line 3, more energy is concentrated around the metal ridge line 3 along with the increase of the width of the metal ridge line 3, and the addition of the metal ridge line 3 enables the boundary condition to have no rotational symmetry any more, so that the polarization of the circular waveguide is improvedThe problem of deflection. However, the width of the metal ridge line 3 cannot be too large, and the too large width of the metal ridge line 3 will affect the field distribution inside the circular waveguide, and further affect the signal transmission. The distribution of the electromagnetic field inside the circular waveguide can be influenced by the difference of the widths of the metal ridge lines 3, so that the transmission loss is increased. Therefore, in the present embodiment, the width range of the metal ridge line 3 is set to be between 0.5mm and 3mm, so that the problem of polarization deflection of the circular waveguide can be solved, and the circular waveguide is reasonably designed according to the outer diameter of the circular waveguide and the frequency of the transmission signal without having a great influence on signal transmission.

As shown in fig. 4, the present invention also provides a method for manufacturing a circular waveguide transmission line for millimeter waves, comprising the steps of:

s1: the method comprises the following steps of (1) extruding and molding a plastic rod by using a double-layer extruding machine to obtain the plastic rod, wherein the obtained plastic rod comprises a core layer and an outer skin layer, the core layer is subjected to physical foaming treatment in a nitrogen or carbon dioxide gas injection mode in the extruding process, and the outer skin layer is not subjected to foaming treatment and uniformly wraps the core layer;

s2: coating a chemical agent on the outer side of the plastic rod, and adhering an outer conductor on the outer surface of the plastic rod in a longitudinal wrapping mode through the chemical agent, wherein in the adhering process, two edges of the outer conductor are overlapped and overlapped on the plastic rod to form a metal ridge line;

s3: through a negative pressure air exhaust process, the molten sheath layer material can be tightly coated on the outer conductor after passing through the plastic extruding machine, so that the outer conductor is tightened and fixed on the plastic rod.

It should be noted that, in step S1, the core layer is physically foamed by injecting nitrogen or carbon dioxide, in order to make the cells foamed by the core layer have uniformity and consistency, the degree of foaming (which refers to the volume ratio between the gas and the material in the core layer) needs to be more than 75%, the core layer is made of a foamed low-density polyolefin material, the skin layer is made of an unfoamed low-density polyolefin material, and the dielectric constants of the materials used for the core layer and the skin layer are both less than 2.25F/m and have similar properties. The core layer adopts a foaming structure, so that the dielectric constant of the material can be effectively reduced, and the high-frequency electricity in the circular waveguide can be reducedAttenuation of the magnetic signal. The nitrogen is nonpolar gas, the influence on high-frequency electromagnetic signals is small, and the carbon dioxide gas can work in a supercritical fluid state in the injection process, so that the foaming degree of the material is improved. The uniformity and consistency of the foam holes are ensured, the transmission stability of electromagnetic wave signals in the circular waveguide can be improved, and the influence on the standing-wave ratio performance of the signal voltage is reduced. Meanwhile, the transmission line can be prevented from being invaded by external moisture in long-term work, so that the transmission performance of the circular waveguide transmission line for the millimeter waves is influenced. In the step S2, the outer conductor is a single-layer copper-plastic composite film, the copper layer of the copper-plastic composite film faces inwards, and the copper layer is adhered to the outer surface of the plastic rod in a longitudinal wrapping mode. When the copper-plastic composite film is longitudinally wrapped and adhered, two edges of the copper-plastic composite film need to be overlapped and lapped on the plastic rod, and the width of the overlapped and lapped part is 0.5 mm-3 mm. The introduction of the metal ridge line can improve the circular waveguide polarization deflection problem in the circular waveguide engineering application. When the circular waveguide has a circularly symmetric structure, the internal structure thereof has slight nonuniformity, and the TE of the master mode₁₁The polarization plane of the field structure will rotate, affecting the signal transmission. The circular waveguide produced by the traditional process is difficult to thoroughly eliminate various structural unevenness generated in the production, transportation, laying and use processes. According to the method, when the copper-plastic composite film is longitudinally wrapped, two edges of the composite film are overlapped to form a metal ridge line along the length direction of the waveguide tube, the metal ridge breaks the rotational symmetry of the boundary condition of the circular waveguide, so that the polarization direction of the waveguide inner field structure is unique, the polarization direction of the waveguide inner field structure is kept unchanged, and the circular waveguide has practicability when being used for long-distance transmission.

In summary, the invention provides a circular waveguide transmission line for millimeter waves and a manufacturing method thereof, wherein a copper-plastic composite film is used as an outer conductor of a circular waveguide to replace the traditional process of continuously drawing and sectionally shaping an all-metal copper (aluminum) tube, so that the continuous and long-length production of the circular waveguide can be realized, the material consumption is greatly reduced, and the production cost is reduced.

The two edges of the outer conductor are overlapped to form the metal ridge line, so that the problem of polarization deflection in the circular waveguide engineering application can be solved, and when the circular waveguide is in a circular symmetrical structure, fine nonuniformity exists in the internal structure of the circular waveguide, and signal transmission is influenced. The circular waveguide produced by the traditional process is difficult to thoroughly eliminate various structural unevenness generated in the production, transportation, laying and use processes. The metal ridge line can destroy the rotational symmetry of the boundary condition of the circular waveguide, so that the polarization direction of the electromagnetic field structure in the waveguide is unique, and the polarization direction of the electromagnetic field structure in the waveguide is kept unchanged, so that the circular waveguide has practicability when being used for long-distance transmission.

The plastic rod is used as the lining layer of the circular waveguide, so that external moisture can be prevented from invading into the waveguide, the electrical performance of the waveguide is improved, and compared with the traditional all-metal copper (aluminum) hollow tube leaky cable waveguide, the plastic rod has elasticity and recoverability, and can prevent the damage in the transportation or construction laying process.

The plastic rod is made of physically foamed low-density polyolefin material, so that the influence on the transmission performance of the circular waveguide at high communication frequency can be reduced, and the outer skin layer can further prevent moisture from invading into the circular waveguide.

The bending performance of the circular waveguide transmission line provided by the invention is superior to that of the traditional all-metal copper (or aluminum) hollow pipe leaky cable waveguide, and the circular waveguide transmission line has the advantages of reducing material consumption, reducing the weight of the transmission line, reducing the cost, facilitating the laying construction and the like.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims (10)

1. Circular waveguide transmission line that millimeter wave used characterized in that includes:

the plastic rod (1) sequentially comprises a core layer (11) and an outer skin layer (12) from inside to outside, wherein the outer skin layer (12) is coated on the core layer (11);

the outer conductor (2), the outer conductor (2) is coated on the plastic rod (1);

the metal ridge line (3) is connected with the outer conductor (2), the metal ridge line (3) is lapped on the plastic rod (1), and the metal ridge line (3) is continuously arranged along the length direction of the plastic rod (1);

a sheath layer (4), wherein the sheath layer (4) is coated on the outer conductor (2).

2. The round waveguide transmission line for millimeter waves according to claim 1, characterized in that the outer conductor (2) is a single-layer copper-plastic composite film comprising a copper layer (21) and a plastic layer (22), the copper layer (21) being connected to the plastic layer (22).

3. The circular waveguide transmission line for millimeter waves according to claim 2, characterized in that the thickness of the copper layer (21) ranges from 0.1mm to 0.2mm, and the thickness of the plastic layer (22) ranges from 0.08mm to 0.2 mm.

4. The circular waveguide transmission line for millimeter waves according to any of claims 1 to 3, characterized in that the width of the metal ridge line (3) is 0.5mm to 3 mm.

5. The circular waveguide transmission line for millimeter waves according to claim 1, characterized in that the core layer (11) is a foamed polyolefin material.

6. The circular waveguide transmission line for millimeter waves according to claim 1, characterized in that the outer skin layer (12) is an unfoamed polyolefin material.

7. The circular waveguide transmission line for millimeter waves according to claim 1, characterized in that the dielectric constant of the material used for the core layer (11) and the outer skin layer (12) is less than 2.25F/m.

8. The circular waveguide transmission line for millimeter waves according to claim 1, characterized in that the ellipticity of said plastic rod (1) is 0.001, and the straightness of said plastic rod (1) is not more than 3mm per meter.

9. The circular waveguide transmission line for millimeter waves according to claim 1, characterized in that the material of the sheath layer (4) is polyolefin, flame-retardant polyolefin or polyvinyl chloride.

10. A method for manufacturing a circular waveguide transmission line for millimeter waves according to any one of claims 1 to 9, comprising the steps of:

s1: the method comprises the following steps of extruding and molding a plastic rod by using a double-layer extruding machine to obtain the plastic rod, wherein the obtained plastic rod comprises a core layer and an outer skin layer, the core layer is subjected to physical foaming treatment in a nitrogen or carbon dioxide gas injection mode in the extruding process, and the outer skin layer is not subjected to foaming treatment and uniformly wraps the core layer;

s2: coating a chemical agent on the outer side of the plastic rod, and adhering an outer conductor on the outer surface of the plastic rod in a longitudinal wrapping mode through the chemical agent, wherein in the adhering process, two edges of the outer conductor are overlapped and overlapped on the plastic rod to form a metal ridge line;

s3: through a negative pressure air exhaust process, the molten sheath layer material can be tightly coated on the outer conductor after passing through the plastic extruding machine, so that the outer conductor is tightened and fixed on the plastic rod.

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