A circularly polarized feeding network and a circularly polarized antenna

Abstract

An embodiment of the present application provides a single-feed circularly polarized feeding network and a circularly polarized antenna, which relate to the technical field of antennas. The circularly polarized feeding network includes a strip line (1), a first phase region (2), a second phase extension line (3), and an outer metal ground (10). The first phase region (2) and the second phase extension line (3) are located on both sides of the strip line (1) and are both connected to the strip line (1). The first phase region (2) and the second phase extension line (3) are used to generate two electric field components with equal amplitudes and a phase difference of 90°. Adjusting the sizes of the first phase region and the second phase extension line can adjust the components with a phase difference of 90°, and the two components are synthesized to form circular polarization. By scaling the circularly polarized feeding network proportionally, it can be used in different frequency bands.

Description

Technical Field

[0001] This application relates to the technical field of antennas, and particularly to a circularly polarized feeding network and a circularly polarized antenna. Background Art

[0002] Circularly polarized electromagnetic waves have the characteristics of strong anti-interference ability and no need to consider polarization mismatch, and are widely used in various places with complex electromagnetic environments. Common forms of circularly polarized antennas include waveguide horn antennas, Yagi antennas, and patch antennas. Patch antennas are widely used in various communication systems due to their low cost, easy integration, and low cost.

[0003] The way to achieve circular polarization of a patch antenna is to generate two modes with equal amplitudes and orthogonal phases through single-feed or dual-feed excitation to form circular polarization.

[0004] Compared with a single-feed circularly polarized patch antenna, a multi-feed antenna has better polarization purity, but has the disadvantage of a complex feeding network, which increases the difficulty of design and processing. This disadvantage is particularly obvious in the design and processing of array antennas.

[0005] Therefore, this application is directed to a single-feed circularly polarized patch antenna. How to design a circularly polarized feeding network with good polarization purity and matching bandwidth is the technical problem to be solved by this application. Summary of the Invention

[0006] The purpose of this application is to provide a circularly polarized feeding network and a circularly polarized antenna to solve the technical problem of how to design a circularly polarized feeding network with good polarization purity and matching bandwidth in the prior art.

[0007] To achieve the above purpose, the embodiments of this application have taken the following technical solutions.

[0008] In a first aspect, the embodiments of this application provide a circularly polarized feeding network, including a strip line, a first phase region, a second phase extension line, and an outer metal ground. The outer metal ground wraps the strip line, the first phase region, and the second phase extension line and leaves an opening at the first end of the strip line. The first phase region and the second phase extension line are located on both sides of the strip line and are both connected to the strip line.

[0009] The first phase region is located: between a first distance from the second end of the strip line and a second distance from the second end of the strip line in the extending direction of the strip line, and between a position at a third distance from the strip line in the vertical direction of the strip line and the strip line itself.

[0010] Wherein, the second distance minus the first distance is equal to the size of the first phase region in the extending direction of the strip line.

[0011] The second phase extension line is located between a second distance from the second end of the strip line and a fourth distance from the second end of the strip line in the extending direction of the strip line, and between a position at a fifth distance from the strip line in the vertical direction of the strip line and the strip line itself.

[0012] Wherein, the difference between the second distance and the fourth distance is the width of the second phase extension line, and the fourth distance is greater than the first distance.

[0013] The first phase region and the second phase extension line are used to generate two electric field components with a phase difference of 90°.

[0014] Optionally, the circular polarization feeding network further includes an open-circuit matching stub, the open-circuit matching stub is insulated from the ground, and is located between the first end of the strip line and the first phase region, and is connected to the strip line.

[0015] Optionally, the open-circuit matching stub is symmetric about the central axis of the strip line.

[0016] Optionally, the circular polarization feeding network further includes a short-circuit matching stub, the short-circuit matching stub is connected to the outer metal ground, and is located between the first end of the strip line and the first phase region, and is connected to the strip line.

[0017] Optionally, the open-circuit matching stub or the short-circuit matching stub is in a straight strip shape.

[0018] Optionally, the open-circuit matching stub or the short-circuit matching stub is perpendicular to the strip line.

[0019] Optionally, the circular polarization feeding network further includes a small matching stub, the area of the small matching stub is smaller than the area of the second phase extension line, the small matching stub and the second phase extension line are on the same side of the strip line, and is connected to the strip line, and is located between the second end of the strip line and the second phase extension line.

[0020] Optionally, the small matching stub is in a strip shape.

[0021] Optionally, the first phase region is oval or rectangular.

[0022] In a second aspect, an embodiment of the present application provides a circular polarization antenna, and the circular polarization antenna includes the circular polarization feeding network of the first aspect.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The circular polarization feeding network provided in the embodiment of the present application realizes the transition from linear polarization to elliptical polarization or circular polarization through the first phase area and the second phase extension line, wherein adjusting the size of the first phase area and the second phase extension line can adjust the component with a phase difference of 90°, and the two components are synthesized to form circular polarization. By scaling the circular polarization feeding network in equal proportion, it can be used in different frequency bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of a circular polarization feeding network provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a circular polarization feeding network with a square first phase region provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram provided in an embodiment of the present application using shading to indicate that a strip line, a first phase region, and a second phase extension line are connected as one;

[0029] Figure 4 A schematic diagram of a circular polarization feeding network with open-circuit matching branches provided in an embodiment of the present application;

[0030] Figure 5 A schematic diagram of a circular polarization feeding network with short-circuit matching branches provided in an embodiment of the present application;

[0031] Figure 6 A schematic diagram of a circular polarization feeding network with small matching branches provided in an embodiment of the present application;

[0032] Figure 7 An exploded diagram of a circularly polarized antenna provided in an embodiment of the present application;

[0033] Figure 8 A schematic diagram of bending a cross-shaped gap into a "卍" or "卐" shape provided in an embodiment of the present application;

[0034] Figure 9 A schematic diagram of rounded corners of a circularly polarized feeding network provided in an embodiment of the present application;

[0035] Figure 10The main polarization pattern and cross-polarization simulation pattern of a circularly polarized antenna provided by an embodiment of the present application at the f0 frequency point;

[0036] Figure 11 A schematic diagram of the S11 of the port of a circularly polarized antenna provided by an embodiment of the present application;

[0037] Figure 12 A schematic diagram of the 3dB axial ratio beamwidth of a circularly polarized antenna provided by an embodiment of the present application at the f0 frequency point;

[0038] Figure 13 A schematic diagram of the bandwidth of a circularly polarized antenna provided by an embodiment of the present application with a normal axial ratio less than 3dB. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments are some but not all of the embodiments of the present application. Usually, the components of the embodiments of the present application described herein can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0041] In the description of the present application, it should be noted that relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium.

[0042] To design a circularly polarized feeding network for a single-feed patch antenna, reference can be made to Figure 1 , an embodiment of the present application provides a circularly polarized feeding network, including a strip line 1, a first phase region 2, a second phase extension line 3, and an outer metal ground 10. The outer metal ground 10 wraps the strip line 1, the first phase region 2, and the second phase extension line 3 and leaves an opening at the first end of the strip line 1 as the port of the electromagnetic wave. The first phase region 2 and the second phase extension line 3 are located on both sides of the strip line 1 and are both connected to the strip line 1.

[0043] To describe the positions of the first phase region 2 and the second phase extension line 3, the following definitions are made and marked in Figure 1 as follows:

[0044] First distance = x1;

[0045] Second distance = x1 + W2;

[0046] Third distance = L3;

[0047] Fourth distance = x4;

[0048] Fifth distance = L5.

[0049] Based on the above definitions of distances, the positions of the first phase region 2 and the second phase extension line 3 can be described as follows:

[0050] 1. First phase region 2 Located: between the first distance (x1) from the second end of the stripline 1 and the second distance (x1 + W2) from the second end of the stripline 1 in the extending direction of the stripline 1, and between the position at the third distance (L3) from the stripline 1 in the vertical direction of the stripline 1 and the stripline 1 itself.

[0051] 2. Second phase extension line 3 Located: between the second distance (x1 + W2) from the second end of the stripline 1 and the fourth distance (x4) from the second end of the stripline 1 in the extending direction of the stripline 1, and between the position at the fifth distance L5 from the stripline 1 in the vertical direction of the stripline 1 and the stripline 1 itself.

[0052] Referring to Figure 1 it can be more easily seen that the following relationships exist for the above distances:

[0053] First phase region 2 In the stripline 1 Dimension in the extending direction (W2) is the second distance (x1 + W2) minus the first distance (x1);

[0054] First phase region 2 In the Dimension in the vertical direction of the stripline 1 is the third distance L3;

[0055] Width of the second phase extension line 3 (W3) is the second distance (x1 + W2) minus the fourth distance (x4);

[0056] Length of the second phase extension line 3 is the fifth distance L5;

[0057] The fourth distance (x4) is greater than the first distance (x1), i.e., W2 > W3.

[0058] The electromagnetic wave is fed into the strip line through the opening port of the outer metal ground 10. The first phase region 2 and the second phase extension line 3 can generate two electric field components with a phase difference of 90°, which can realize circular polarization or elliptical polarization as a polarization converter. By further adjusting the sizes of the first phase region and the second phase extension line, the magnitudes of the components with a phase difference of 90° can be adjusted, and two components with equal amplitudes are synthesized to form circular polarization.

[0059] The first phase region 2 can be oval (including circular), rectangular (including square), such as Figure 2 , and the strip line 1 and the second phase extension line 3 are in a straight strip shape. To more clearly show the entire feeding network, reference can be made to Figure 3 , the strip line 1, the first phase region 2, and the second phase extension line 3 are connected conductors, that is, the shaded part in the figure. The outer white part is the outer metal ground 10, and the outer metal ground 10 and the shaded part are located on a layer of insulating medium.

[0060] To achieve impedance matching between the first phase region 2 and the second phase extension line 3 and the strip line 1, the capacitance of the entire circular polarization feeding network can be adjusted, and matching stubs can be set.

[0061] Figure 4 The figure shows a schematic diagram of the matching stub being the open-circuit matching stub 4. The open-circuit matching stub 4 is insulated from the ground, and is located between the first end of the strip line 1 and the first phase region 2, and is connected to the strip line 1.

[0062] The open-circuit matching stub 4 can be set to be symmetrical about the central axis of the strip line 1. The open-circuit matching stub 4 is in a straight strip shape, with equal lengths on both sides, and the formed pattern is uniform, so that one side will not be too long, saving the occupied area.

[0063] Adjusting the position and length of the open-circuit matching stub 4 can adjust the capacitance of the entire circular polarization feeding network to achieve impedance matching.

[0064] Figure 5 The figure shows a schematic diagram of the matching stub being the short-circuit matching stub 4'. The short-circuit matching stub 4' is also located between the first end of the strip line 1 and the first phase region 2, and is also connected to the strip line 1. The difference from the open-circuit matching stub 4 lies in : The short-circuit matching stub 4' is connected to the outer metal ground 10. Similarly, the shape and size of the short-circuit matching stub 4' can be adjusted to achieve the effect of impedance matching.

[0065] For standardized design and convenient printing, the above-mentioned open-circuit matching stub 4 or short-circuit matching stub 4' can be set to be in a strip shape perpendicular to the strip line 1.

[0066] In addition to the above-mentioned arrangement of a matching branch between the first end of the stripline 1 and the first phase zone 2 , a matching branch may also be arranged between the second end of the stripline 1 and the second phase extension line 3 . Figure 6 The small matching branch 5 is located between the second end of the stripline 1 and the second phase extension line 3. The area of the small matching branch 5 is smaller than the area of the second phase extension line 3, which plays a role of fine-tuning. The small matching branch 5 and the second phase extension line 3 are located on the same side of the stripline 1, connected to the stripline 1, and located between the second end of the stripline 1 and the second phase extension line 3.

[0067] Based on the above embodiments, the embodiments of the present application also provide a circularly polarized antenna, including a radiation layer, a slot layer and a feeder layer. The slot layer is located between the radiation layer and the feeder layer. In order to fix the relative positions of the various parts, a dielectric layer or other support may be provided. Figure 7 An implementation is shown, where the layers are set up as follows:

[0068] 1. Radiation layer 101: There are 4 metal parasitic patches and an outer metal ground. The metal parasitic patch can be a square with a side length of 1 / 4 of the wavelength;

[0069] 2. Dielectric layer 102: The material TSM-DS3 can be selected, with a thickness of 0.254 mm, and the outer ring has a metal ground and a metal gap layer connected to the radiation layer 101 by metalized vias;

[0070] 3. Metal gap layer 103: A gap is provided. The gap can be in the shape of a cross. In order to reduce the area occupied by the cross, each end point of the cross can be bent (such as Figure 8 , the dotted line is before bending), forming a "卍" or "卐" shape (the bending direction of each end point can also be changed to form other shapes, or only a part of the four ends can be bent), which is conducive to miniaturization;

[0071] 4. Outer metal stratum 104;

[0072] 5. Feeder layer 105: The circular polarization feed network is printed on the downward surface of the dielectric layer (the material may be Rogers 4450F, thickness 0.1 mm) as the feeder layer 105;

[0073] 6. Dielectric layer 106: The material may be Rogers 5880, with a thickness of 0.1 mm. A metallized via hole (not shown in the figure) similar to the dielectric layer 102 is also provided to connect the bottom metal ground 107 and the outer metal ground of the feeder layer 105;

[0074] 7. Bottom metal ground 107.

[0075] Electromagnetic waves are fed into the port through a microstrip line, and through the feeding network, the linear polarization is converted into circular polarization. The circularly polarized electromagnetic waves are coupled and fed to the 4 patch antennas on the surface through the slots, realizing the radiation of circularly polarized electromagnetic waves in free space.

[0076] The applicant has carried out adaptive design and testing on the above circularly polarized antenna. For example, in the circularly polarized feeding network, referring to Figure 9 , the width of the microstrip line 1 is reduced at the position below the small matching stub 5, and the right angle formed by the connection of the microstrip line 1 and other parts is converted into a rounded corner, and the following test results are obtained:

[0077] Figure 10 The main polarization pattern and cross-polarization simulation pattern of the circularly polarized antenna at the f0 frequency point are shown.

[0078] Figure 11 The port S11 of the circularly polarized antenna is shown. From Figure 11 , it can be seen that the port S11 of the circularly polarized antenna satisfies S11 ≤ -10 dB in the frequency range of 71 - 93 GHz.

[0079] Figure 12 The 3 dB axial ratio beamwidth of the circularly polarized antenna at the f0 frequency point is shown. From Figure 12 , it can be seen that the circularly polarized antenna satisfies an axial ratio of less than 3 dB in the beamwidth range of ±75°.

[0080] Figure 13 The bandwidth with a normal axial ratio of less than 3 dB of the circularly polarized antenna is shown. From Figure 13 , it can be seen that the antenna satisfies an axial ratio of less than 3 dB in the frequency range of 75 - 82 GHz.

[0081] In addition, by scaling the circularly polarized feeding network proportionally, it can be used in different frequency bands. For example, the designed circularly polarized feeding network has an application frequency point of 80 GHz. If you want to achieve an application at the 40 GHz frequency point, you can scale up the sizes of the circularly polarized feeding network, slots, and radiation patches by two times and then carry out more detailed design to achieve it.

[0082] The illustrated feeding network enables the vertical polarization component to have a phase lead of 90° over the horizontal polarization component, realizing right-handed circular polarization. Similarly, by mirroring the feeding network about the center of the microstrip line, the vertical polarization component can have a phase lag of 90° over the horizontal polarization component, realizing left-handed circular polarization. Or by setting the relationship between the third distance and the fifth distance, the left-handed and right-handed circular polarizations can be switched: L3 < L5, realizing the vertical polarization phase leading the horizontal polarization, right-handed; L3 > L5, realizing the vertical polarization phase lagging the horizontal polarization, left-handed.

[0083] The device and system embodiments described above are merely illustrative. One can select some or all of the modules according to actual needs to achieve the objectives of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative efforts.

[0084] The above is only a preferred specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in this application should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A circularly polarized feeding network, characterized in that It includes a stripline (1), a first phase region (2), a second phase extension line (3), and an outer metal ground (10); the outer metal ground (10) wraps the stripline (1), the first phase region (2), and the second phase extension line (3) and leaves an opening at the first end of the stripline (1); the first phase region (2) and the second phase extension line (3) are located on both sides of the stripline (1) and are both connected to the stripline (1). The first phase region (2) is located between a first distance from the second end of the stripline (1) and a second distance from the second end of the stripline (1) in the extending direction of the stripline (1), and between a position at a third distance from the stripline (1) in the vertical direction of the stripline (1) and the stripline (1) itself. Wherein, the second distance minus the first distance is equal to the dimension of the first phase region (2) in the extending direction of the stripline (1). The second phase extension line (3) is located between a second distance from the second end of the stripline (1) and a fourth distance from the second end of the stripline (1) in the extending direction of the stripline (1), and between a position at a fifth distance (L5) from the stripline (1) in the vertical direction of the stripline (1) and the stripline (1) itself. Wherein, the second distance minus the fourth distance is the width of the second phase extension line (3), and the fourth distance is greater than the first distance. The first phase region (2) and the second phase extension line (3) are used to generate two electric field components with a phase difference of 90°.

2. The circularly polarized feeding network according to claim 1, wherein The circularly polarized feeding network further includes an open-circuit matching stub (4), the open-circuit matching stub (4) is insulated from the ground, and is located between the first end of the stripline (1) and the first phase region (2), and is connected to the stripline (1).

3. The circularly polarized feeding network according to claim 2, wherein The open-circuit matching stub (4) is symmetric about the central axis of the stripline (1).

4. The circularly polarized feeding network according to claim 1, wherein The circularly polarized feeding network further includes a short-circuit matching stub (4’), the short-circuit matching stub (4’) is connected to the outer metal ground (10), and is located between the first end of the stripline (1) and the first phase region (2), and is connected to the stripline (1).

5. The circular polarization feeding network according to any one of claims 2-4, characterized in that, Wherein, the open-circuit matching stub (4) or the short-circuit matching stub (4’) is in a straight strip shape.

6. The circular polarization feeding network according to claim 5, wherein The open-circuit matching stub (4) or the short-circuit matching stub (4’) is perpendicular to the stripline (1).

7. The circularly polarized feeding network according to claim 1, wherein The circularly polarized feeding network further includes a small matching stub (5), the area of the small matching stub (5) is smaller than the area of the second phase extension line (3), the small matching stub (5) and the second phase extension line (3) are located on the same side of the stripline (1), and are connected to the stripline (1), and is located between the second end of the stripline (1) and the second phase extension line (3).

8. The circular polarization feeding network according to claim 7, wherein The small matching stub (5) is in a strip shape.

9. The circularly polarized feeding network according to claim 1, characterized in that, The first phase region (2) is oval or rectangular.

10. A circularly polarized antenna, characterized in that, The circularly polarized antenna includes the circularly polarized feeding network according to any one of claims 1-9.

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