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 manufacturing method thereof

technical field

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

Background technique

With the continuous development of modern communication technology, spectrum resources are becoming more and more scarce, and the millimeter-wave band has a huge space for spectrum resource development. Therefore, how to develop and utilize the millimeter-wave spectrum resources originally used in satellite and radar military systems has become the fifth generation. The focus of mobile communication technology. Among them, the transmission of millimeter-wave signals between devices faces the problem of improvement and replacement due to the sharp increase in the attenuation of traditional coaxial cables in the millimeter-wave band.

Circular waveguide is a cylindrical waveguide with a circular section. Circular waveguides have the characteristics of low loss and dual polarization. They are often used in antenna feeders, and can also be used as long-distance transmission lines, and are widely used as microwave resonators. As a communication transmission line, the circular waveguide used to transmit millimeter wave electromagnetic signals has many advantages: the transmission power is higher under the same cross-sectional perimeter (because the cross-sectional area of the circle is the largest), and the transmission attenuation is small. Compared with the rectangular waveguide, it can be transported in a tray, and the construction and deployment are relatively simple. However, since the circular waveguide has strict requirements on the process accuracy and product consistency of the waveguide to realize millimeter wave signal transmission, in order to realize the wider application of the circular waveguide, the structure and production process of the circular waveguide need to be improved.

SUMMARY OF THE INVENTION

In view of the above shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a circular waveguide transmission line with a waveguide structure and stable electrical performance and a manufacturing method thereof.

In order to solve the above-mentioned technical problems, the present invention first provides the following technical solutions: a circular waveguide transmission line for millimeter waves, including:

a plastic rod, which sequentially includes a core layer and an outer skin layer from the inside to the outside, and the outer skin layer covers the core layer;

an outer conductor, the outer conductor is wrapped on the plastic rod;

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

a sheath layer, the sheath layer covering the outer conductor.

By adopting the above technical solution, the metal ridge line is introduced into the waveguide structure, which can effectively improve the polarization deflection problem and improve the practicability of long-distance transmission. External moisture penetrates into the transmission line, thereby affecting the electrical performance of the transmission line. At the same time, compared with the traditional all-metal copper (aluminum) empty tube leaky cable waveguide, the circular waveguide transmission line for millimeter waves with plastic rods as the inner lining is more elastic and recoverable, which can avoid the transportation or construction deployment process. damage in.

In an embodiment of the present 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 to the plastic layer.

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

By adopting the above technical solution, the copper-plastic composite film is used as the outer conductor of the circular waveguide, which can improve the performance of the waveguide, and at the same time, the size selection of the copper layer and the plastic layer can better meet the communication requirements without affecting the circular waveguide. Other properties of transmission lines.

In an embodiment of the present invention, the width of the metal ridge is 0.5 mm˜3 mm.

By adopting the above technical solution, the polarization problem generated in the application process of the circular waveguide can be better improved without affecting other properties of the circular waveguide.

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 materials used in the core layer and the outer skin layer is less than 2.25 F/m.

By adopting the above technical solution, on the one hand, outside moisture can be prevented from invading the transmission line during long-term operation, thereby affecting the transmission performance of the circular waveguide transmission line for millimeter waves; on the other hand, the core layer and the outer skin layer adopt relative dielectric constants low, the effect of the filler on high frequency signal transmission can be reduced.

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

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

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

By adopting the above technical scheme, the circular waveguide can be protected from mechanical damage, and at the same time, it can have flame retardant properties when required.

In order to solve the above-mentioned technical problems, the present invention also provides a manufacturing method of a circular waveguide transmission line for millimeter waves, comprising the following steps:

S1: The plastic rod is extruded by a double-layer extruder, and the obtained plastic rod includes a core layer and an outer skin layer, and the core layer is physically foamed by injecting nitrogen or carbon dioxide gas during the extrusion process. treatment, the outer skin layer is not foamed, and evenly wraps the core layer;

S2: Coating chemical agents on the outside of the plastic rod, and adhering the outer conductor to the outer surface of the plastic rod through the chemical agent in a longitudinally wrapping manner. During the adhesion process, the two edges of the outer conductor overlap and overlap. forming metal ridges on the plastic rod;

S3: After passing the molten sheath layer material through the extruder, it can be tightly wrapped on the outer conductor through a negative pressure air extraction process, so as to tighten and fix the outer conductor on the plastic rod.

By adopting the above technical solution, the present invention forms a metal ridge line by overlapping the two edges of the outer conductor on the plastic rod, which not only improves the polarization deflection problem of the circular waveguide transmission line in practical application, but also greatly improves the The realizability of process production can realize continuous and large-length industrial-scale production, and improve the consistency and stability of products.

Of course, it is not necessary for any product embodying the present invention to achieve all of the above-described advantages simultaneously.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic structural diagram of a circular waveguide transmission line for millimeter waves provided by the present invention;

2 is a schematic cross-sectional view of a circular waveguide transmission line for millimeter waves provided by the present invention;

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

FIG. 4 is a flow chart of the manufacturing method of the circular waveguide transmission line for millimeter waves provided by the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Unless otherwise defined, technical or scientific terms used in the present invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which the present invention belongs. The terms "first," "second," and similar terms used herein do not denote any order, quantity, or importance, but are merely used to distinguish different components. "Comprises" or "comprising" and similar words mean that the elements or things appearing before the word encompass the elements or things recited after the word and their equivalents, but do not exclude other elements or things. Words like "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "Down", "Left", "Right", etc. are only used to represent the relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

其中：δ为趋肤深度，ω为角频率，Μ为磁导率，ρ为电阻率，通过计算可得：As shown in FIGS. 1 to 3 , the present invention provides a circular waveguide transmission line for millimeter waves, which is provided with a plastic rod 1 , an outer conductor 2 , a metal ridge line 3 and a sheath layer 4 sequentially from inside to outside. The plastic rod 1 sequentially includes a core layer 11 and an outer skin layer 12 from the inside to the outside, and the outer skin layer 12 covers the core layer 11 . The outer conductor 2 is coated on the plastic rod 1, that is, the outer conductor 2 is coated on the outer skin. The metal ridge line 3 is connected with the outer conductor 2 , and the metal ridge line 3 is overlapped 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 covers the outer conductor 2 . In this embodiment, the outer conductor 2 is wrapped on the plastic rod 1 in an integrated longitudinal wrapping manner. In this 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, and the thickness of the copper layer 21 ranges The thickness of the plastic layer 22 can be made of ethylene acrylic acid copolymer or ethylene methacrylic acid copolymer, and the thickness of the plastic layer 22 ranges from 0.08 mm to 0.2 mm. The choice of the thickness of the copper-plastic composite film needs to meet the communication requirements without affecting the performance of the circular waveguide transmission line for millimeter waves. Further, according to the calculation formula of the skin depth of the high-frequency electromagnetic field transmitted in the metal conductor:

Where: δ is the skin depth, ω is the angular frequency, M is the magnetic permeability, ρ is the resistivity, and can be obtained by calculation:

Therefore, the thickness of the copper layer 21 of the copper-plastic composite film can meet the communication requirements at high frequencies, and can be used as the outer conductor 2 of the circular waveguide transmission line for millimeter waves without affecting the high frequency electrical performance of the circular waveguide transmission line for millimeter waves. . The metal ridge line 3 is introduced into the waveguide structure, and the metal ridge line 3 is continuously arranged along the length direction of the plastic rod 1, which can effectively improve the polarization deflection problem and improve the practicability of long-distance transmission. At the same time, the plastic rod is used as a circular The inner lining of the waveguide transmission line can prevent external moisture from invading the transmission line, thereby affecting the electrical performance of the transmission line. At the same time, compared with the traditional all-metal copper (aluminum) empty tube leaky cable waveguide, the circular waveguide transmission line for millimeter waves with plastic rods as the inner lining is more elastic and recoverable, which can avoid the transportation or construction deployment process. damage in.

As shown in FIG. 1 to FIG. 3 , in this embodiment, the plastic rod 1 has a double-layer structure, from the inside to the outside, the core layer 11 and the outer skin layer 12 are respectively, and the core layer 11 is a low-density polyolefin after physical foaming. materials, or other materials with excellent dielectric constant properties. The outer skin layer 12 is an unfoamed low-density polyolefin material, or other materials with the same or similar dielectric constant properties as the core layer material, and the dielectric constant of the core layer 11 and the material used for the outer skin layer 12 is less than 2.25F /m. In this embodiment, the plastic rod is used as the inner lining of the waveguide, which can improve the structural stability and electrical performance stability of the circular waveguide transmission line for millimeter waves. At the same time, on the one hand, it can prevent the moisture in the surrounding environment from gradually invading during the long-term operation of the transmission line, thereby affecting the electrical properties of the circular waveguide. On the other hand, the plastic material is more elastic and recoverable, which can prevent transportation or construction. The damage during the deployment process further improves the stability of the product structure. In this embodiment, the outer diameter of the plastic rod 1 has a linear relationship with the cutoff wavelength of the transmission signal, and the outer diameter of the plastic rod 1 can be selected according to the formula according to the communication operating frequency and the cutoff frequency of the circular waveguide. For example, the transmission of high-frequency signals in a circular waveguide is limited by the cut-off wavelength, that is, when the main modes of transmission in the circular waveguide are TE ₁₁ and TM ₀₁ , respectively, the corresponding cut-off wavelength and the diameter of the circular waveguide can be derived according to the following formula: λc =3.412*D/2, λc=2.61*D/2, where λc 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, the outer diameter of the plastic rod 1 should be controlled The deviation is less than ±0.05mm, the ellipticity is 0.001, and the straightness is not more than 3mm per meter. Of course, in practical applications, for a circular waveguide, it is necessary to distinguish between the two cases where the equivalent dielectric constant ε _g of the circular waveguide is greater than or equal to and less than 1, while ε _g is determined by the core layer 11 . It is determined by parameters such as dielectric constant, waveguide operating frequency, and waveguide cut-off wavelength. Therefore, to determine the outer diameter of the circular waveguide, the equivalent dielectric constant of the inner core layer 11 of the plastic rod, the working radiation mode of the waveguide, the working frequency, the cut-off wavelength of the waveguide, the size and period of the slot for the signal should be considered at the same time. and many more. In this embodiment, the sheath layer 4 is made of polyolefin, but it is not limited to this, and can also be made of flame-retardant polyolefin, polyvinyl fluoride, etc., as long as the purpose of protecting the cable from mechanical damage is possible, and at the same time, it has resistance when necessary. Burn function.

As shown in FIG. 1 to FIG. 3 , in this embodiment, a metal ridge line 3 is formed by overlapping two edges of the outer conductor 2 and overlapping on the plastic rod. The shape of the metal ridge line 3 can be a rectangle or a circle. etc., the maximum size of the metal ridge line 3 can be changed within a range smaller than the radius of the circular waveguide. In this embodiment, the width of the metal ridge line 3 ranges from 0.5 mm to 3 mm. When there is no metal ridge line 3 in the circular waveguide, the boundary conditions of the circular waveguide are rotationally symmetric, and the field distribution of the TE ₁₁ -mode electric field polarization plane deflected at any angle is the solution of Maxwell's equations under the same boundary conditions. The electric field inside the waveguide increases as the width of the metal ridge 3 increases, and as the width of the metal ridge 3 increases, more energy will be concentrated around the metal ridge 3. The addition of the metal ridge 3 makes the The boundary conditions no longer have rotational symmetry, thereby improving the polarization deflection problem of circular waveguides. However, the width of the metal ridge line 3 should not be too large. If the width of the metal ridge line 3 is too large, the field distribution inside the circular waveguide will be affected, thereby affecting the transmission of signals. The difference in the width of the metal ridge line 3 can affect the distribution of the electromagnetic field inside the circular waveguide, thereby increasing the transmission loss. Therefore, in this embodiment, the width range of the metal ridge line 3 is set between 0.5 mm and 3 mm, which can improve the polarization deflection problem of the circular waveguide, and will not have a great impact on the signal transmission. Reasonable design is carried out according to the outer diameter of the circular waveguide and the frequency of the transmitted signal.

As shown in Figure 4, the present invention also provides the manufacture method of the circular waveguide transmission line that millimeter wave is used, comprises the following steps:

S1: The plastic rod is extruded by a double-layer extruder, and the obtained plastic rod includes a core layer and an outer skin layer, and the core layer is physically foamed by injecting nitrogen or carbon dioxide gas during the extrusion process. treatment, the outer skin layer is not foamed, and evenly wraps the core layer;

S2: Coating chemical agents on the outside of the plastic rod, and adhering the outer conductor to the outer surface of the plastic rod through the chemical agent in a longitudinally wrapping manner. During the adhesion process, the two edges of the outer conductor overlap and overlap. forming metal ridges on the plastic rod;

S3: After passing the molten sheath layer material through the extruder, it can be tightly wrapped on the outer conductor through a negative pressure air extraction process, so as to tighten and fix the outer conductor on the plastic rod.

It should be noted that, in step S1, the core layer is subjected to physical foaming treatment by injecting nitrogen gas or carbon dioxide gas. The volume ratio between the All are less than 2.25F/m and have similar performance. The core layer adopts a foamed structure, which can effectively reduce the dielectric constant of the material and reduce the attenuation of high-frequency electromagnetic signals in the circular waveguide. Nitrogen is a non-polar gas and has little effect on high-frequency electromagnetic signals, while carbon dioxide gas can work in a supercritical fluid state during the injection process to improve the foaming degree of the material. Ensuring the uniformity and consistency of the cells can improve the stability of the electromagnetic wave signal transmission inside the circular waveguide and reduce the influence on the performance of the signal VSWR. At the same time, outside moisture can be prevented from invading the transmission line during long-term operation, thereby affecting the transmission performance of the circular waveguide transmission line for millimeter waves. In step S2, a single-layer copper-plastic composite film is selected for the outer conductor, and the copper layer of the copper-plastic composite film is turned inward, and is adhered to the outer surface of the plastic rod in a longitudinally wrapping manner. When the copper-plastic composite film is adhered to the vertical wrap, the two edges of the copper-plastic composite film need to be overlapped and overlapped on the plastic rod, and the width of the overlapped part is 0.5mm to 3mm. The introduction of metal ridges can improve circular waveguide polarization deflection in circular waveguide engineering applications. When the circular waveguide is a circularly symmetric structure, there is a slight inhomogeneity in its internal structure, and the polarization plane of the main mode TE ₁₁ field structure will rotate, affecting the signal transmission. However, it is difficult to completely eliminate various structural inhomogeneities during production, transportation, laying and use of circular waveguides produced by traditional processes. In this method, during the longitudinal wrapping process of the copper-plastic composite film, the two edges of the composite film are overlapped to form a metal ridge line along the length of the waveguide. The polarization direction of the circular waveguide is unique, and the polarization direction of the inner field structure of the waveguide remains unchanged, which makes the circular waveguide practical for long-distance transmission.

In summary, the present invention provides a circular waveguide transmission line for millimeter waves and a manufacturing method thereof. The copper-plastic composite film is used as the outer conductor of the circular waveguide instead of the traditional all-metal copper (aluminum) tube for continuous drawing. The segmented shaping process can realize continuous and large-length production of circular waveguides, and at the same time greatly reduce material consumption and production costs.

The invention can improve the polarization deflection problem in the engineering application of the circular waveguide by overlapping the two edges of the outer conductor to form a metal ridge line. sex, affecting signal transmission. However, it is difficult to completely eliminate various structural inhomogeneities during production, transportation, laying and use of circular waveguides produced by traditional processes. The metal ridge line can destroy the rotational symmetry of the boundary conditions 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 remains unchanged. practicality.

In the invention, the plastic rod is used as the inner lining of the circular waveguide, which can prevent external moisture from invading the waveguide and improve the electrical performance of the waveguide. Recoverability prevents damage during transportation or construction deployment.

The plastic rod of the invention adopts the low-density polyolefin material after physical foaming, which can reduce the influence on the transmission performance of the circular waveguide at high communication frequencies, and the outer skin layer can further prevent moisture from invading the circular waveguide.

The bending performance of the circular waveguide transmission line provided by the invention is better than that of the traditional all-metal copper (or aluminum) empty tube leaky cable waveguide, and has the advantages of reduced material consumption, lightened transmission line weight, reduced cost, and convenient deployment and construction.

The above-disclosed preferred embodiments of the present invention are provided only to help illustrate the present invention. The preferred embodiments do not exhaust all the details, nor do they limit the invention to only the described embodiments. Obviously, many modifications and variations are possible in light of the content of this specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is to be 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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