Leaky circularly polarized waveguide

Abstract

The application discloses a leaky circularly polarized waveguide, which comprises, from back to front, a closed short-circuit end, a coaxial waveguide, a matching unit and a feeding unit; the coaxial waveguide comprises a first inner conductor, a first insulating layer and a first outer conductor which are sequentially arranged from inside to outside; the first insulating layer is wrapped outside the first inner conductor, and the first outer conductor is wrapped outside the first insulating layer; along the signal transmission direction, a slot array is arranged in a matrix on the outer surface of the first outer conductor; the slot array is composed of a plurality of groups of slot array elements arranged along the length direction of the outer surface of the first outer conductor; each group of slot array elements is a circular ring structure formed by a plurality of slot units arranged in a circle; each slot unit is composed of a first slot and a second slot arranged in pairs, and the first slot and the second slot are arranged in a non-contacting orthogonal mode. The leaky circularly polarized waveguide has the advantages of enhancing signal coverage strength and capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication transmission, and in particular to a leaky circular polarized waveguide. BACKGROUND

[0002] In recent years, China plans to build a large number of urban rail transit lines, including many subway projects. At the same time, as of now, the urban rail transit lines that have been opened and operated in China have formed a considerable scale, among which subways account for the majority. The demand for 5G signal coverage along the rail transit line is increasing.

[0003] Leaky coaxial cables provide a solution to the problem of signal coverage blind area, but due to the structural limitations of leaky coaxial cables themselves, the disadvantage of increased loss with increasing operating frequency needs to be overcome. The train control system (CBTC, Communication Based Train Control System) in the 5.8 GHz frequency band requires more efficient and reliable radio wave coverage. Therefore, leaky circular polarized waveguides suitable for high frequency bands have gradually attracted attention.

[0004] The actual communication environment requires the radiation characteristics of the leaky circular polarized waveguide to be more flexible and variable in order to achieve more uniform and stable radio wave coverage, which puts new requirements on the structural design of the leaky circular polarized waveguide. If a flexible waveguide structure with flexible characteristics is used, the length of continuous production can be greatly increased, achieving the effect of reducing the difficulty of implementation of the laying project. In addition, the flexible waveguide structure can reduce the number of intermediate joints, reduce the loss at the joints (caused by reflection, loss and noise, etc.), and help improve the coverage effect. From the aspect of transmission characteristics, the basic mode of the flexible circular waveguide is between the TE 10 mode of the rectangular waveguide and the TE 11 mode of the circular waveguide, and its transmission characteristics are basically not affected by slight size changes. Through the mode converter and the matching connection with other transmission lines, the compatibility of the overall signal coverage system is effectively improved.

[0005] Therefore, how to improve the gain of the leaky circular waveguide to meet the CBTC signal coverage in the 5.8 GHz frequency band and adapt to the narrow tunnel environment is a technical problem faced by those skilled in the art. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art.

[0007] To this end, the present application proposes a leaky circular polarized waveguide, which has the advantages of enhancing signal coverage strength and capacity.

[0008] The leaky circularly polarized waveguide according to the embodiment of the present application comprises, from back to front, a closed short-circuit end, a coaxial waveguide, a matching unit and a feeding unit; the coaxial waveguide comprises, from inside to outside, a first inner conductor, a first insulating layer and a first outer conductor, the first insulating layer is wrapped outside the first inner conductor, and the first outer conductor is wrapped outside the first insulating layer; along the signal transmission direction, a slit array is arranged in a matrix on the outer surface of the first outer conductor, the slit array is composed of a plurality of groups of slit array elements arranged along the length direction of the outer surface of the first outer conductor, and each group of slit array elements is a circular ring structure formed by a plurality of slit units circumferentially surrounding each other; each slit unit is composed of a first slit and a second slit arranged in pairs, and the first slit and the second slit are arranged in contactless orthogonality.

[0009] The leaky circularly polarized waveguide according to the embodiment of the present application is suitable for 5.8GHz CBTC frequency band signal coverage, the first slit and the second slit are arranged in orthogonality, which can enhance the signal coverage strength and realize the orthogonal superposition of the radiated electromagnetic wave signals at the same position on the signal transmission path; on the other hand, the electric field superposition forms a circularly polarized electromagnetic wave, improves the polarization diversity effect of the leaky waveguide, reduces the signal mutual coupling through polarization diversity, improves the data flow peak rate, further enhances the coverage ability of the signal, and thus reduces the cost of relay equipment, the cost of early laying and the cost of later maintenance in the overall coverage system.

[0010] According to an embodiment of the present application, the first slit and the second slit are both rectangular slits.

[0011] According to an embodiment of the present application, in the same slit unit, the first slit and the second slit have a spacing , and the spacing is 1mm-4mm.

[0012] According to an embodiment of the present application, the length of the first slit is 18mm-28mm, and the width of the first slit is 3.5mm-6.5mm; the length of the second slit is 18mm-28mm, and the width of the second slit is 3.5mm-6.5mm.

[0013] According to an embodiment of the present application, the included angle between the first slit and the central axis of the coaxial waveguide is -45°, and the included angle between the second slit and the central axis of the coaxial waveguide is 45°.

[0014] According to one embodiment of the present invention, the matching unit consists of three coaxial transmission lines with different inner diameters and the same outer diameter, namely, a first coaxial transmission line, a second coaxial transmission line, and a third coaxial transmission line arranged sequentially from back to front; the feeding unit is composed of a coaxial tapered line, which matches the large-size coaxial waveguide to the SMA adapter; the closed short-circuit terminal is composed of a coaxial transmission line with a shorted rear end.

[0015] According to one embodiment of the present invention, the inner conductor of the first coaxial transmission line is designated as the second inner conductor, the inner conductor of the second coaxial transmission line is designated as the third inner conductor, the inner conductor of the third coaxial transmission line is designated as the fourth inner conductor, and the inner conductor of the coaxial tapered line is designated as the fifth inner conductor; the maximum diameter of the rear end of the fifth inner conductor is... Larger than the diameter of the third inner conductor The diameter of the third inner conductor Larger than the diameter of the fourth inner conductor The diameter of the fourth inner conductor Larger than the diameter of the first inner conductor The diameter of the first inner conductor Larger than the diameter of the second inner conductor The diameter of the second inner conductor It is greater than the minimum diameter of the front end of the fifth inner conductor.

[0016] According to one embodiment of the present invention, the length of the coaxial waveguide is greater than the length of the feed unit. The length of the power supply unit Greater than the length of the second coaxial transmission line segment The length of the second coaxial transmission line Greater than the length of the third coaxial transmission line The length of the third coaxial transmission line Greater than the length of the first coaxial transmission line segment .

[0017] According to one embodiment of the present invention, the outer diameter of the closed short-circuit end, the outer diameter of the coaxial waveguide, the outer diameter of the matching unit, and the maximum outer diameter of the rear end of the feed unit are equal.

[0018] According to one embodiment of the present invention, the inner diameter of the closed short-circuit end is equal to the inner diameter of the coaxial waveguide.

[0019] Other features and advantages of the present application will be set forth in the descriptions that follow, and in part will be apparent from the description, or can be learned by practice of the application. The purposes and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0020] To make the above objectives, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are referred to for a detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0022] Figure 1 is a structural schematic diagram of a leaky circular polarized waveguide of the present application;

[0023] Figure 2 is Figure 1 is a sectional view at A-A in

[0024] Figure 3 is Figure 1 is a sectional view at B-B in

[0025] Figure 4 is Figure 1 is a structural schematic diagram of a coaxial waveguide and a closed short-circuit end in

[0026] Figure 5 is Figure 3 is a partial structural schematic diagram in

[0027] Figure 6 is a normal slot pair on the outer wall of the leaky circular polarized waveguide of the present application;

[0028] Figure 7 is a slot pair at the last end of the outer wall of the leaky circular polarized waveguide of the present application and subjected to angle cutting treatment;

[0029] Figure 8 is an electric field vector schematic diagram of a vertical slot pair of the outer wall of the leaky circular polarized waveguide of the present application;

[0030] Figure 9 is an S11 parameter actual measurement and simulation diagram of the leaky circular polarized waveguide of the present application in the 5G to 6G frequency band;

[0031] Figure 10 is an axial ratio simulation diagram of the leaky waveguide provided by the present application in a horizontal plane;

[0032] Figure 11 is a simulation diagram of radiation efficiency of the leaky waveguide in the 5G to 6G frequency band provided by the present application.

[0033] The reference signs in the drawings are as follows: 1, coaxial waveguide; 101, first inner conductor; 102, first insulating layer; 103, first outer conductor; 2, matching unit; 3, feeding unit; 301, fifth inner conductor; 4, closed short end; 5, slot unit; 501, first slot; 502, second slot; 6, first section of coaxial transmission line; 601, second inner conductor; 7, second section of coaxial transmission line; 701, third inner conductor; 8, third section of coaxial transmission line; 801, fourth inner conductor; 9, port for mounting standard SMA adapter. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below with reference to examples thereof shown in the attached drawings, wherein the same or similar reference signs represent the same or similar elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only and are for the purpose of explanation of the present application and should not be understood as limiting the present application.

[0035] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the features defined as “first” and “second” can be explicitly or implicitly included one or more of the features. In the description of the present application, unless otherwise specified and limited, the term “a plurality of” means two or more.

[0036] In the description of the present application, it needs to be understood that, unless otherwise explicitly specified and limited, the terms “mounting”, “connecting”, “connection” should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] The leaky circularly polarized waveguide of the embodiments of the present application is described in detail below with reference to the drawings.

[0038] See Figure 1 , the leakage circularly polarized waveguide comprises, from back to front, a closed short-circuit end 4, a coaxial waveguide 1, a matching unit 2 and a feeding unit 3. Among them, the central axis of the coaxial waveguide 1, the central axis of the matching unit 2, the central axis of the feeding unit 3 and the central axis of the closed short-circuit end 4 are located on the same straight line.

[0039] See Figure 3 , the coaxial waveguide 1 comprises a first inner conductor 101, a first insulating layer 102 and a first outer conductor 103 distributed in turn from inside to outside, the first insulating layer 102 is wrapped outside the first inner conductor 101, and the first outer conductor 103 is wrapped outside the first insulating layer 102.

[0040] See Figure 1 and see Figure 4 , along the signal transmission direction, a slot array is arranged in a matrix on the outer surface of the first outer conductor 103, the slot array is composed of a plurality of groups of slot array elements arranged along the length direction of the outer surface of the first outer conductor 103, that is, a plurality of groups of slot array elements are periodically arranged in the length direction of the outer surface of the first outer conductor 103. Each group of slot array elements is a circular ring structure formed by a plurality of slot units 5 circumferentially surrounding.

[0041] Among them, each slot unit 5 is composed of a pair of first slot 501 and second slot 502, and the first slot 501 and the second slot 502 are arranged in a non-contacting orthogonal manner. It should be noted that the non-contacting orthogonal arrangement means that the spatial geometric positional relationship of the first slot 501 and the second slot 502 is vertical, but they do not contact each other. Such design makes the electromagnetic wave signals radiated from the first slot 501 and the second slot 502 realize orthogonal superposition, which can enhance the signal coverage strength on the one hand, and the electric field superposition forms a circularly polarized electromagnetic wave, which improves the polarization diversity effect of the leakage waveguide.

[0042] See Figure 6 , according to an embodiment of the present application, the first slot 501 and the second slot 502 are both rectangular slots. In the same slot unit 5, the first slot 501 and the second slot 502 have a gap , and the gap is 1mm-4mm, which needs to be simulated and optimized; it should be noted that one long side of the first slot 501 and one short side of the second slot 502 are parallel and adjacent, and the distance between the long side of the first slot 501 and the short side of the second slot 502 is the gap between the first slot 501 and the second slot 502.

[0043] Among them, the length is 18mm-28mm, the width of the first slot 501 is 3.5mm-6.5mm; the length of the second slot 502 is 18mm-28mm, the width of the second slot 502 is 3.5mm-6.5mm. The angle between the first slot 501 and the central axis of the coaxial waveguide 1 is -45°, the angle between the second slot 502 and the central axis of the coaxial waveguide 1 is 45°. Through such a design, the first slot 501 and the second slot 502 can radiate electromagnetic field to the outside, and by optimizing the slot size, the working frequency of the transmission signal, the signal blind area coverage and other requirements can be met, and in addition, the orthogonal superposition of the radiated electromagnetic signal can be better realized, further enhancing the strength of signal coverage.

[0044] See Figure 5 , according to an embodiment of the present application, the matching unit 2 is designed based on the coaxial waveguide 1, and the matching unit 2 is composed of three coaxial transmission lines with different inner diameters and the same outer diameter, which are the first coaxial transmission line 6, the second coaxial transmission line 7 and the third coaxial transmission line 8 arranged from back to front.

[0045] See Figure 5 , the feeding unit 3 is composed of a coaxial tapered line, and the interface at the front end of the feeding unit 3 is a port 9 equipped with a standard SMA adapter, and the coaxial tapered line is used to match the large-size coaxial waveguide 1 to the SMA adapter. It should be noted that the design of the coaxial tapered line is based on the characteristic impedance formula of the coaxial line, and the ratio of the inner diameter to the outer diameter of the tapered coaxial line is always kept unchanged, and the controlled impedance is 50 ohms, which is connected to the standard SMA adapter joint to avoid electromagnetic wave reflection caused by impedance mutation.

[0046] See Figure 3 , the closed short-circuit end 4 is composed of a coaxial transmission line with a rear-end short circuit, and the inner diameter of the closed short-circuit end 4 is equal to the inner diameter of the coaxial waveguide 1, that is, the inner conductor diameter of the closed short-circuit end 4 is equal to the diameter of the first inner conductor 101 of the coaxial waveguide 1. In addition, the outer conductor diameter of the closed short-circuit end 4 is equal to the diameter of the first outer conductor 103 of the coaxial waveguide 1.

[0047] See Figure 3 and Figure 5 , according to an embodiment of the present application, the inner conductor of the first coaxial transmission line 6 is set as the second inner conductor 601, the inner conductor of the second coaxial transmission line 7 is set as the third inner conductor 701, the inner conductor of the third coaxial transmission line 8 is set as the fourth inner conductor 801, and the inner conductor of the coaxial tapered line is set as the fifth inner conductor 301; the rear end of the fifth inner conductor 301 has a maximum diameter greater than the diameter of the third inner conductor 701 the diameter of the third inner conductor 701 is greater than the diameter of the fourth inner conductor 801 the diameter of the fourth inner conductor 801 is greater than the diameter of the first inner conductor 101 the diameter of the first inner conductor 101 is greater than the diameter of the second inner conductor 601 the diameter of the second inner conductor 601 is greater than the minimum diameter of the front end of the fifth inner conductor 301.

[0048] see Figure 3 According to an embodiment of the present application, the length of the coaxial waveguide 1 is greater than the length of the feeding unit 3 the length of the feeding unit 3 is greater than the length of the second section of coaxial transmission line 7 the length of the second section of coaxial transmission line 7 is greater than the length of the third section of coaxial transmission line 8 the length of the third section of coaxial transmission line 8 is greater than the length of the first section of coaxial transmission line 6 .

[0049] see Figure 2 According to an embodiment of the present application, the outer diameter of the closed short-circuit end 4 the outer diameter of the coaxial waveguide 1 the outer diameter of the matching unit 2 and the maximum outer diameter of the rear end of the feeding unit 3 are equal.

[0050] The circularly polarized design method of the leaky circularly polarized waveguide includes the following steps:

[0051] Step 1, see Figure 2 and Figure 4 the total length of the coaxial waveguide 1 and the closed short-circuit end 4 (radiation part) of the leaky circularly polarized waveguide is the diameter of the first inner conductor 101 is the diameter of the first outer conductor 103 is the slot unit 5 is a pair of slots (first slot 501 and second slot 502) arranged orthogonally on the first outer conductor 103.

[0052] see Figure 6 the length of the slot is the width of the slot is the two slots (first slot 501 and second slot 502) in one slot unit 5 are respectively inclined by 45° in two different directions, and the distance from the center of the first slot 501 to the central axis of the coaxial waveguide 1 is , the distance from the center of the second slot 502 to the central axis of the coaxial waveguide 1 is , the distance from the center of the first slot 501 to the central axis of the coaxial waveguide 1 is , and the distance from the center of the first slot 501 to the center of the second slot 502 is , and . The distance from the edge of the first slot 501 to the edge of the second slot 502 is .

[0053] See Figure 1 and Figure 4 , four slot units 5 are designed on the outer wall of the coaxial waveguide 1 to form a group of slot array elements in a circle to realize omnidirectional radiation.

[0054] See Figure 4 , four groups of slot array elements are designed on the outer wall of the coaxial waveguide 1, arranged from back to front as first group of slot array elements, second group of slot array elements, third group of slot array elements, and fourth group of slot array elements. The distance between the front end of the first group of slot array elements and the front end of the second group of slot array elements is , the distance between the front end of the second group of slot array elements and the front end of the third group of slot array elements is , and the distance between the front end of the third group of slot array elements and the front end of the fourth group of slot array elements is .

[0055] See Figure 7 , because the back end of the leaky circularly polarized waveguide adopts a short-circuit structure closed by metal, the position of the closed structure causes a part of the last group of slot array elements to be cut off. The structure of this circle of slots is different from that of the other three circles of slots.

[0056] Step 2, the matching unit 2 (matching part) of the leaky circularly polarized waveguide is designed based on the coaxial waveguide 1, see Figure 3 , which is composed of three coaxial transmission lines with different inner diameters and unchanged outer diameters, with lengths of , and , and inner conductor diameters of , and .

[0057] Step 3, set the two vertical slits in a slit unit 5 along the X-axis electric field intensity amplitude as Ex0, set the two vertical slits in a slit unit 5 along the Y-axis electric field intensity amplitude as Ey0, in fact, due to the two vertical slits (first slit 501 and second slit 502) in a slit unit 5 radiate electric field intensity Ex0≠ Ey0, so the actual radiated circularly polarized wave is not a completely standard circular polarization, but an elliptical polarization wave, that is, the axial ratio of the radiated electromagnetic wave is affected by the electric field intensity radiated by the two slits.

[0058] Step 4, see Figure 8 In a slit unit 5, due to the two slits (first slit 501 and second slit 502) along the axis distance is The position difference between the reflected wave when the electromagnetic wave from the feed port direction passes through the first slit 501 and the reflected wave when it passes through the second slit 502 is That is, the corresponding phase difference is 180°, taking the first slit 501 as the reference plane, the reflected waves are opposite and superimposed on the reference plane, and they cancel each other out. The antenna designed with such a slit unit 5 structure has a good reflection coefficient. Figure 8 and represent two radiation directions, X, Y and Z represent the XYZ coordinate system.

[0059] Step 5, see Figure 1 and Figure 4 In each group of slit elements, including four slit units 5, four slit units 5 are uniformly distributed on the outer wall (first outer conductor 103) of the coaxial waveguide 1 around the central axis of the coaxial waveguide 1, realizing omnidirectional coverage.

[0060] see Figure 1 and Figure 4 In order to improve the gain of the antenna, take a circle of slit units 5 as an omnidirectional circularly polarized unit of the antenna, and set four omnidirectional circularly polarized units on the outer wall of the coaxial waveguide 1 to form a slit array. The feed of the antenna is along the axial direction, that is, the array is equivalent to a serial feed, and according to the formula (where, represents the excitation phase difference of adjacent elements; represents the wave number of electromagnetic wave under certain boundary conditions; represents the element spacing, here referring to the spacing of adjacent slits; represents the angle between the maximum value direction of the main lobe of the array antenna and the extension direction of the linear array), it can be known that in order to make the directional diagram formed by the array perpendicular to the array direction, it is necessary to ensure that the feed phase of the radiating unit is consistent. The circularly polarized elements are distributed along the axial direction, and the spacing between the elements is designed as to ensure in-phase feeding. ​

[0061] Step 6, the medium filled between the inner and outer conductors of the coaxial line is Teflon, i.e. the material of the insulating layer is Teflon, and the dielectric constant is 2.1. The medium filled between the coaxial lines is beneficial to reducing the size of the leaky waveguide. In addition, in order to obtain high gain, array design must be performed, and in order to suppress the appearance of 3D radiation grating lobes, the array element spacing must satisfy (wherein, is the number of array elements, the value range of is 4-10, and is a positive integer), and the dielectric constant is 2.1, according to (wherein, represents the free space wavelength; represents the Teflon dielectric constant), the array element spacing is , which satisfies the requirement of lobe suppression. Through HFSS (three-dimensional high-frequency electromagnetic simulation software) simulation, it can be seen that the suppression of the lobe is good in the case of filling the medium. Of course, CST (three-dimensional electromagnetic field simulation software) simulation can also be performed.

[0062] Step 7, the last circle of slits close to the closed short-circuit end is not the same as the other three circles of slits. Compared with the normal slits, this circle of slits is cut at an angle, and the height of the cut angle is (the back end of the waveguide is a short-circuit coaxial transmission line. In order to achieve the effect of reducing electromagnetic wave reflection, the slits close to the short-circuit surface need to be cut at an angle). The back end short circuit will cause total reflection of electromagnetic waves, reducing the circular polarization performance of the radiated electric wave. Therefore, in order to avoid the above-mentioned effect, the slits at the back end need to be cut at an angle to form irregular slits, which are equivalent to the matching coaxial transmission line at the back end, thereby reducing the reflection of electromagnetic waves caused by impedance mismatch.

[0063] Step 8, see Figure 7 , the cut angle height is simulated and optimized by using electromagnetic simulation software HFSS, which is expected to further reduce the circular polarization loss and optimize the axial ratio of the radiated electric wave.

[0064] Step 9, the structure parameters and sizes of the leaky waveguide after simulation and optimization by using three-dimensional electromagnetic simulation software HFSS are given. See the following table for details:

[0065]

[0066] The values in the above table are the values after simulation and optimization, and belong to an example of the waveguide. It needs to be explained that any product implementing the present application does not necessarily need to achieve all the advantages described above. ​

[0067] See Figure 9 In the 5GHz to 6GHz frequency band, the return loss of the leaky circularly polarized waveguide is below -10dB, indicating good impedance matching. The simulation value curve trend of S11 parameters is basically consistent with the measured value curve trend, providing a basis for subsequent design optimization.

[0068] See Figure 10 Select 5.2GHz, 5.5GHz and 5.8GHz three frequency points, the axial ratio of the electromagnetic field of the leaky circularly polarized waveguide is basically maintained below 3dB within the azimuth angle of 360 degrees, realizing the basic requirement of circular polarization and avoiding the polarization matching loss caused by single polarization.

[0069] See Figure 11 In the 5GHz to 5.9GHz frequency band, the electromagnetic wave radiation efficiency of the leaky circularly polarized waveguide is above 80% with small fluctuation, and the stable and reliable actual radiation efficiency means wide application prospect.

[0070] The leaky circularly polarized waveguide of the application is suitable for covering the 5.8GHz CBTC frequency band signal, and the first slit 501 and the second slit 502 are arranged orthogonally, which can enhance the signal coverage strength and realize the orthogonal superposition of the radiated electromagnetic wave signals at the same position on the signal transmission path, reduce the signal mutual coupling through polarization diversity, improve the data flow peak rate, and further enhance the signal coverage capability, thereby reducing the relay device cost, the early laying and the maintenance cost of the overall coverage system. By arranging the first slit 501 and the second slit 502 at-45° and 45° respectively with respect to the first direction and aligning the spatial positions, the electromagnetic waves radiated by the leaky waveguide can be orthogonally superimposed, the signal coherence gain is enhanced, and when the polarization axial ratio is less than 3dB, the circularly polarized signal coverage is formed, greatly enhancing the signal coverage strength.

[0071] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0072] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and application of the present application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present application, which is defined by the following claims and their equivalents.

Claims

1. A leaky circularly polarized waveguide, characterized in that: It includes, from back to front, a closed short-circuit terminal (4), a coaxial waveguide (1), a matching unit (2), and a feeding unit (3); The coaxial waveguide (1) includes a first inner conductor (101), a first insulating layer (102) and a first outer conductor (103) arranged sequentially from the inside to the outside. The first insulating layer (102) covers the outside of the first inner conductor (101), and the first outer conductor (103) covers the outside of the first insulating layer (102). Along the signal transmission direction, a slot array is arranged in a matrix on the outer surface of the first outer conductor (103). The slot array is composed of several groups of slot elements arranged along the length direction of the outer surface of the first outer conductor (103). Each group of slot elements is a ring structure formed by multiple slot units (5) surrounding it circumferentially. Each slot unit (5) consists of a pair of first slots (501) and second slots (502), and the first slots (501) and the second slots (502) are arranged orthogonally without contact. The total length L of the coaxial waveguide (1) and the closed short-circuit end (4) is 161.1 mm; and the gap closest to the closed short-circuit end (4) is chamfered with a chamfer height of D. g .

2. The leaky circularly polarized waveguide according to claim 1, characterized in that: Both the first gap (501) and the second gap (502) are rectangular gaps.

3. The leaky circularly polarized waveguide according to claim 2, characterized in that: In the same slot unit (5), the first slot (501) and the second slot (502) are spaced by a distance d. s And the interval d s The diameter is 1mm to 4mm.

4. The leaky circularly polarized waveguide according to claim 2, characterized in that: The length of the first gap (501) is 18mm to 28mm, and the width of the first gap (501) is 3.5mm to 6.5mm; The length of the second gap (502) is 18mm to 28mm, and the width of the second gap (502) is 3.5mm to 6.5mm.

5. The leaky circularly polarized waveguide according to claim 2, characterized in that: The first slit (501) has an angle α of -45° with the central axis of the coaxial waveguide (1), and the second slit (502) has an angle α of 45° with the central axis of the coaxial waveguide (1).

6. The leaky circularly polarized waveguide according to claim 1, characterized in that: The matching unit (2) consists of three coaxial transmission lines with different inner diameters and constant outer diameters, namely the first coaxial transmission line (6), the second coaxial transmission line (7), and the third coaxial transmission line (8) arranged sequentially from back to front; The feed unit (3) is composed of a coaxial tapered line, which matches the large-size coaxial waveguide (1) to the SMA adapter. The closed short-circuit terminal (4) is composed of a coaxial transmission line with the back end short-circuited.

7. The leaky circularly polarized waveguide according to claim 6, characterized in that: The inner conductor of the first coaxial transmission line (6) is set as the second inner conductor (601), the inner conductor of the second coaxial transmission line (7) is set as the third inner conductor (701), the inner conductor of the third coaxial transmission line (8) is set as the fourth inner conductor (801), and the inner conductor of the coaxial gradient line is set as the fifth inner conductor (301). The maximum diameter D4 of the rear end of the fifth inner conductor (301) is greater than the diameter D2 of the third inner conductor (701), the diameter D2 of the third inner conductor (701) is greater than the diameter D3 of the fourth inner conductor (801), and the diameter D3 of the fourth inner conductor (801) is greater than the diameter D of the first inner conductor (101). i The diameter D of the first inner conductor (101) i The diameter D1 of the second inner conductor (601) is greater than the minimum diameter of the front end of the fifth inner conductor (301).

8. The leaky circularly polarized waveguide according to claim 7, characterized in that: The length of the coaxial waveguide (1) is greater than the length L4 of the feed unit (3), the length L4 of the feed unit (3) is greater than the length L2 of the second coaxial transmission line (7), the length L2 of the second coaxial transmission line (7) is greater than the length L3 of the third coaxial transmission line (8), and the length L3 of the third coaxial transmission line (8) is greater than the length L1 of the first coaxial transmission line (6).

9. The leaky circularly polarized waveguide according to claim 6, characterized in that: The outer diameter of the closed short-circuit terminal (4), the outer diameter of the coaxial waveguide (1), the outer diameter of the matching unit (2), and the maximum outer diameter of the rear end of the feed unit (3) are all equal.

10. The leaky circularly polarized waveguide according to claim 9, characterized in that: The inner diameter of the closed short-circuit terminal (4) is equal to the inner diameter of the coaxial waveguide (1).

Images