Omnidirectional circularly polarized antenna, cascade antenna and antenna array

Abstract

The present invention relates to the field of wireless communications, and in particular to an omnidirectional circularly polarized antenna, a cascade antenna, and an antenna array. The omnidirectional circularly polarized antenna includes a feeding structure, a connecting rod, a first double helix structure, a second double helix structure, a third double helix structure, and a fourth double helix structure; the helix radius of the first double helix structure is smaller than the helix radius of the third double helix structure; one end of the first double helix structure is coaxially connected to one end of the second double helix structure via the feeding structure, and the other end is coaxially connected to the third double helix structure via the connecting rod; the other end of the second double helix structure is coaxially connected to the fourth double helix structure via the connecting rod; the first and third double helix structures are symmetrical about the center of the feeding structure and the second and fourth double helix structures; the sum of the helix lengths of the first and second double helix structures is 0.5λ; the helix lengths of the third and fourth double helix structures are both 0.5λ. The antenna operates in a 1.5λ mode, which improves radiation resistance and thus improves radiation efficiency.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and in particular to an omnidirectional circularly polarized antenna, a cascade antenna and an antenna array. Background Art

[0002] In modern wireless communications, circularly polarized antennas offer significant advantages for suppressing polarization mismatch, multipath effects, and Faraday rotation effects. Because circularly polarized waves can be decomposed into the superposition of two orthogonal linearly polarized waves, whether used as a receiving or transmitting antenna, the placement angle of the circularly polarized antenna is not affected by the polarization characteristics of the other antenna, and electromagnetic wave signals can be effectively transmitted between the two antennas. Furthermore, circularly polarized antennas can receive linearly polarized electromagnetic waves from various directions. Even if the polarization direction of linearly polarized electromagnetic waves changes due to multipath reflection and Faraday rotation during transmission, the circularly polarized antenna can still effectively receive the signal. Furthermore, in specific scenarios such as end-to-end communication, wearable device communication, and in-vehicle communication, antennas are generally required to have a wide radiation coverage range. Furthermore, with the development of modern communication systems, antennas are generally required to be smaller in size to save system space. Therefore, compared to linearly polarized antennas, compact omnidirectional circularly polarized antennas have a wider range of applications.

[0003] Common methods for achieving omnidirectional circular polarization are: 1. Using an orthogonal combination of electric dipoles and magnetic dipoles to generate omnidirectional circular polarization. Because the conditions for generating circular polarization require that the amplitudes of the vertical polarization component and the horizontal polarization component are equal and the phase difference is 90°, and the phases of the electric dipole and the magnetic dipole naturally differ by 90°, it is only necessary to adjust the corresponding amplitudes to keep them equal to achieve omnidirectional circular polarization. Although the combination of electric dipoles and magnetic dipoles can generate omnidirectional circular polarization, the longitudinal size of the antenna is too large; 2. Using a polarizer to convert omnidirectional linear polarization into omnidirectional circular polarization. Using a polarizer to achieve omnidirectional circular polarization also has the problem of large volume; 3. Combining multiple directional circularly polarized antennas in a circular pattern The antennas are evenly arranged in a circular polarization pattern, with each antenna responsible for circular polarization within a certain angular range, thus achieving omnidirectional circular polarization. However, achieving omnidirectional circular polarization using this method is not only bulky but also complex, making the feed network difficult to design. Fourth, omnidirectional circular polarization is achieved using a normal-mode helical antenna. Helical antennas are generally composed of a highly conductive metal wire arranged in a spiral. When the helix circumference is approximately one wavelength, the antenna operates in an axial mode, with the strongest radiation occurring in the axial direction of the helix. When the helix circumference is much smaller than one wavelength, the antenna operates in a normal mode, with the strongest radiation perpendicular to the helix axis. When the helix circumference is much larger than one wavelength, the antenna becomes a conical-mode helical antenna. Although both axial-mode and normal-mode helical antennas can achieve circularly polarized radiation, axial-mode helical antennas have a smaller radiation range and are larger in size due to their axial radiation. In space-constrained situations, normal-mode helical antennas offer advantages due to their smaller antenna size. A normal-mode helical antenna can be roughly equated to a combination of an electric dipole and a loop antenna. When a traditional normal mode helical antenna generates omnidirectional circularly polarized radiation, its helical pitch s, helical circumference c, and operating wavelength λ need to satisfy Under this condition, the spiral is extremely compact but has extremely low radiation resistance. When connected to a commonly used 50-ohm coaxial connector, it will cause severe impedance mismatch, resulting in extremely low radiation efficiency and difficult to apply in practice. Summary of the Invention

[0004] The present invention provides an omnidirectional circularly polarized antenna, a cascade antenna and an antenna array, which are used to solve the technical problem in the prior art that when the normal-mode helical antenna generates omnidirectional circularly polarized radiation, the radiation resistance is small, and severe impedance mismatch occurs when connected to a coaxial connector, resulting in low radiation efficiency and difficulty in practical application.

[0005] The first aspect of the present invention provides an omnidirectional circularly polarized antenna, comprising:

[0006] a first double helix structure, a second double helix structure, a third double helix structure, a fourth double helix structure, a feeding structure, and a connecting rod;

[0007] The helical radius of the first double helical structure is smaller than the helical radius of the third double helical structure;

[0008] One end of the first double helix structure is coaxially connected to one end of the second double helix structure through the feeding structure, and the other end is coaxially connected to the third double helix structure through the connecting rod;

[0009] The other end of the second double helix structure is coaxially connected to the fourth double helix structure through the connecting rod;

[0010] The first double helix structure and the third double helix structure are symmetrical with respect to the feeding structure and the second double helix structure and the fourth double helix structure;

[0011] The sum of the helical lengths of the first double helical structure and the second double helical structure is 0.5λ;

[0012] The helical lengths of the third double helical structure and the fourth double helical structure are both 0.5λ.

[0013] In a first possible implementation of the antenna of the first aspect, the first double helix structure and the third double helix structure have the same cross-sectional shape;

[0014] The first double helix structure and the connecting rod have the same cross-sectional shape.

[0015] In combination with the first possible implementation of the antenna of the first aspect, in a second possible implementation of the antenna of the first aspect, the cross-sectional shape of the first double helix structure is rectangular, circular, elliptical, or diamond-shaped.

[0016] In a third possible implementation of the antenna of the first aspect, the first double helix structure, the second double helix structure, the third double helix structure, the fourth double helix structure and the connecting rod are all formed of metal conductors.

[0017] In a fourth possible implementation of the antenna of the first aspect, the number of spiral turns N1 of the first double helix structure is 2;

[0018] The number of helical turns N2 of the third double helix structure is 1.

[0019] In combination with the first aspect, the first possible implementation of the antenna of the first aspect, the second possible implementation of the antenna of the first aspect, the third possible implementation of the antenna of the first aspect, or the fourth possible implementation of the antenna of the first aspect, in the fifth possible implementation of the antenna of the first aspect, the helical radius r_helix of the first double helix structure is 1.5 mm;

[0020] The pitch of the turns of the first double helix structure is pitch = 9 mm;

[0021] The spiral radius of the third double helix structure r_loop=9 mm;

[0022] The turn pitch of the third double helix structure is pitch_loop=10.25 mm.

[0023] In combination with the first aspect, the first possible implementation of the antenna of the first aspect, the second possible implementation of the antenna of the first aspect, the third possible implementation of the antenna of the first aspect, or the fourth possible implementation of the antenna of the first aspect, in a sixth possible implementation of the antenna of the first aspect, the connecting rod is perpendicular to the axis of the first double helix structure;

[0024] The two spiral arms of the first double helix structure are respectively connected to the two spiral arms of the third double helix structure through one of the connecting rods;

[0025] The two spiral arms of the second double helix structure are respectively connected to the two spiral arms of the fourth double helix structure through one of the connecting rods.

[0026] In combination with the first aspect, the first possible implementation of the antenna of the first aspect, the second possible implementation of the antenna of the first aspect, the third possible implementation of the antenna of the first aspect, or the fourth possible implementation of the antenna of the first aspect, in a seventh possible implementation of the antenna of the first aspect, the feeding structure includes two metal blocks and a feeding plate;

[0027] Two metal blocks and one feed plate form an I-shaped structure;

[0028] Two ends of one metal block in the extension direction are respectively connected to the two spiral arms of the first double helix structure, and two ends of another metal block in the extension direction are respectively connected to the two spiral arms of the second double helix structure;

[0029] The extending direction of the metal block is perpendicular to the axis of the first double helix structure.

[0030] A second aspect of the present invention provides a cascade antenna, comprising:

[0031] Any possible omnidirectional circularly polarized antenna provided by the first aspect;

[0032] The omnidirectional circularly polarized antennas are cascaded in the axial direction.

[0033] A third aspect of the present invention provides an antenna array, comprising:

[0034] N omnidirectional circularly polarized antennas of any possible type provided by the first aspect, where N is an integer greater than or equal to 2;

[0035] The N omnidirectional circularly polarized antennas are arranged in a direction perpendicular to the axial direction.

[0036] It can be seen from the above technical solutions that the present invention has the following advantages:

[0037] An omnidirectional circularly polarized antenna provided by the present invention is provided with a first double helix structure, a second double helix structure, a third double helix structure, a fourth double helix structure, a feeding structure and a connecting rod; the first double helix structure and the second double helix structure have the same shape; the third double helix structure and the fourth double helix structure have the same shape; the spiral radius of the first double helix structure is smaller than the spiral radius of the third double helix structure; one end of the first double helix structure is coaxially connected to one end of the second double helix structure through the feeding structure, and the other end is coaxially connected to the third double helix structure through the connecting rod; the other end of the second double helix structure is coaxially connected to the fourth double helix structure through the connecting rod; the first double helix structure and the second double helix structure are symmetrical about the center of the feeding structure; the third double helix structure and the fourth double helix structure are symmetrical about the center of the feeding structure; the sum of the spiral lengths of the first double helix structure and the second double helix structure is 0.5λ, and the spiral lengths of the third double helix structure and the fourth double helix structure are both 0.5λ. The first, second, third, and fourth double helix structures can all be approximately viewed as a combination of an electric small dipole and a loop antenna. Due to the natural 90° phase difference between the dipole and the loop, circular polarization can be achieved as long as the amplitudes of the vertical polarization component and the horizontal polarization component generated by the dipole and the loop are kept equal. By increasing the turn spacing between the first and second double helix structures, the radiation resistance is effectively increased, thereby avoiding the occurrence of impedance mismatch and improving the radiation efficiency. At the same time, by providing the third and fourth double helix structures to compensate for the horizontal polarization component, it is ensured that the radiation resistance is increased while meeting the circular polarization conditions, which can be applied in practice.

[0038] At the same time, by setting the sum of the helical lengths of the first double helix structure and the second double helix structure to 0.5λ, the helical length of the third double helix structure to 0.5λ, and the helical length of the fourth double helix structure to 0.5λ, the omnidirectional circularly polarized antenna operates in 1.5λ mode, which significantly improves the radiation resistance compared to the traditional 0.5λ operating mode, thereby improving the radiation efficiency.

[0039] In addition, the first double helix structure, the second double helix structure, the third double helix structure and the fourth double helix structure are symmetrical about the axis, which not only ensures the symmetry of the directional pattern of the omnidirectional circularly polarized antenna, but also further enhances the gain of the omnidirectional circularly polarized antenna.

[0040] In addition, the first double helix structure and the third double helix structure are cascaded, and the second double helix structure and the fourth double helix structure are cascaded through a connecting rod, which effectively reduces the overall size and realizes the miniaturization of the omnidirectional circularly polarized antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 A schematic diagram of the structure of an omnidirectional circularly polarized antenna in the ZY plane provided by an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the structure of an omnidirectional circularly polarized antenna in the ZX plane provided by an embodiment of the present invention;

[0044] Figure 3 FIG. 11 is a simulation diagram of an omnidirectional circularly polarized antenna provided in an embodiment of the present invention;

[0045] Figure 4 An antenna horizontal plane axial ratio diagram of an omnidirectional circularly polarized antenna provided in an embodiment of the present invention;

[0046] Figure 5 The radiation pattern of an omnidirectional circularly polarized antenna provided in an embodiment of the present invention;

[0047] in:

[0048] 1. First double helix structure 2. Second double helix structure 3. Third double helix structure

[0049] 4. Fourth double helix structure 5. Feed structure 51. Metal block

[0050] 52. Feed plate 6. Connecting rod. DETAILED DESCRIPTION

[0051] The embodiments of the present invention provide an omnidirectional circularly polarized antenna, a cascaded antenna and an antenna array, which are used to solve the technical problem that when the normal-mode helical antenna in the prior art generates omnidirectional circularly polarized radiation, the radiation resistance is small, and severe impedance mismatch occurs when connected to a coaxial connector, resulting in low radiation efficiency and difficulty in practical application.

[0052] In order to make the purposes, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0054] In the description of the embodiments of the present application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, replaceable connections, or integral connections. They can also refer to mechanical connections or electrical connections. They can also refer to direct connections or indirect connections through an intermediate medium. They can also refer to internal connections between two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0055] Existing omnidirectional circularly polarized antennas suffer from large size, complex design, and difficulty designing feed networks. This invention provides a new, symmetrical, and miniaturized omnidirectional circularly polarized antenna. This antenna, based on a cascaded normal-mode spiral structure, offers advantages such as a wide circular polarization range (omnidirectional circularly polarized radiation on the horizontal plane), simple feeding, symmetrical radiation patterns, and a compact structure. It is suitable for applications requiring omnidirectional circularly polarized radiation and limited antenna installation space.

[0056] Example 1

[0057] See also Figure 1-5 , an omnidirectional circularly polarized antenna provided by an embodiment of the present invention includes:

[0058] A first double helix structure 1, a second double helix structure 2, a third double helix structure 3, a fourth double helix structure 4, a feeding structure 5 and a connecting rod 6; the helical radius of the first double helix structure 1 is smaller than the helical radius of the third double helix structure 3; one end of the first double helix structure 1 is coaxially connected to one end of the second double helix structure 2 via the feeding structure 5, and the other end is coaxially connected to the third double helix structure 3 via the connecting rod 6; the other end of the second double helix structure 2 is coaxially connected to the fourth double helix structure 4 via the connecting rod 6; the first double helix structure 1 and the third double helix structure 3 are symmetrical about the feeding structure 5 and the second double helix structure 2 and the fourth double helix structure 4; the sum of the helical lengths of the first double helix structure and the second double helix structure 2 is 0.5λ; the helical lengths of the third double helix structure 3 and the fourth double helix structure 4 are both 0.5λ.

[0059] It should be noted that:

[0060] The feeding structure 5 converts radio waves into electrical signals when the omnidirectional circularly polarized antenna receives signals, and converts electrical signals into radio waves when the omnidirectional circularly polarized antenna transmits signals. The shape of the feeding structure 5 is not specifically limited.

[0061] The connecting rod 6 is used to cascade the first double helix structure 1 and the third double helix structure 3 , and is used to cascade the second double helix structure 2 and the fourth double helix structure 4 .

[0062] Coaxial connection means that the axis lines of the two connected are collinear.

[0063] The first double helix structure 1 and the third double helix structure 3 are symmetrical about the center of the feeding structure 5 and the second double helix structure 2 and the fourth double helix structure 4. That is, the local structure formed by the connection of the first double helix structure 1 and the third double helix structure 3 and the local structure formed by the connection of the second double helix structure 2 and the fourth double helix structure 4 are symmetrical about the center of the feeding structure 5. At the same time, it is defined that the shapes of the first double helix structure 1 and the second double helix structure 2 are the same, and the shapes of the third double helix structure 3 and the fourth double helix structure 4 are the same.

[0064] The sum of the helical lengths of the first double helix structure 1 and the second double helix structure 2 is 0.5λ, that is, the sum of the helical length of one helical arm of the first double helix structure 1 and the helical length of one helical arm of the second double helix structure 2 is equal to 0.5λ.

[0065] The helical lengths of the third double helix structure 3 and the fourth double helix structure 4 are both 0.5λ, that is, the helical lengths of the two helical arms in the third double helix structure 3 are both 0.5λ, and the helical lengths of the two helical arms in the fourth double helix structure 4 are both 0.5λ.

[0066] The beneficial effects of this embodiment include:

[0067] ① The first double helix structure 1, the second double helix structure 2, the third double helix structure 3, and the fourth double helix structure 4 can all be approximately viewed as a combination of a small electric dipole and a loop antenna. Due to the natural 90° phase difference between the dipole and the loop, circular polarization can be achieved by ensuring that the amplitudes of the vertical polarization component and the horizontal polarization component are equal. By increasing the turn spacing of the first double helix structure 1 and the second double helix structure 2, the radiation resistance is effectively increased, thereby avoiding the occurrence of impedance mismatch and improving radiation efficiency. At the same time, by providing the third helix structure 3 and the fourth helix structure 4 with larger helix radii, compensation is provided for the horizontal polarization component, ensuring that the amplitudes of the horizontal polarization component and the vertical polarization component remain equal. This prevents the vertical polarization component from becoming greater than the horizontal polarization component when the turn spacing of the first double helix structure 1 and the second double helix structure 2 is increased, thereby destroying the axial ratio of omnidirectional circular polarization. This ensures that the radiation resistance is improved while satisfying the circular polarization conditions, and is applicable to practical applications.

[0068] ② By setting the sum of the helical lengths of the first double helix structure 1 and the second double helix structure 2 to 0.5λ, the helical length of the third double helix structure 3 to 0.5λ, and the helical length of the fourth double helix structure 4 to 0.5λ, the omnidirectional circularly polarized antenna operates in 1.5λ mode, which significantly improves the radiation resistance compared to the traditional 0.5λ operating mode, thereby improving the radiation efficiency.

[0069] ③ The first double helix structure 1, the second double helix structure 2, the third double helix structure 3 and the fourth double helix structure 4 are all arranged to be symmetrical about the axis, which not only ensures the symmetry of the directional pattern of the omnidirectional circularly polarized antenna, but also further enhances the gain of the omnidirectional circularly polarized antenna.

[0070] ④ The first double helix structure 1 and the third double helix structure 3 are cascaded through the connecting rod 6, and the second double helix structure 2 and the fourth double helix structure 4 are cascaded, which effectively reduces the overall size and realizes the miniaturization of the omnidirectional circularly polarized antenna.

[0071] For ease of description, the first, second, third and fourth double helix structures are used to replace the first double helix structure 1 , the second double helix structure 2 , the third double helix structure 3 and the fourth double helix structure 4 , and other similar descriptions are similar.

[0072] Preferred embodiments of cross-sectional shapes: The first double helix structure 1 and the third double helix structure 3 have the same cross-sectional shape. Because the first double helix structure 1 and the second double helix structure 2 are centrosymmetrical structures, and the third double helix structure 3 and the fourth double helix structure 4 are centrosymmetrical structures, the first, second, third, and fourth double helix structures have the same cross-sectional shape. The cross-sectional shape of a double helix structure can be understood as the shape of a cross section perpendicular to the extension direction of the helical arms of the double helix structure. The first double helix structure 1 and the connecting rod 6 have the same cross-sectional shape, that is, the shape of the distal end of the connecting rod 6 in the extension direction is the same as the cross-sectional shape of the first double helix structure 1. For example, when the cross-sectional shape is rectangular, the width of the helical arms of the first double helix structure 1 is equal to the width of the connecting rod 6, and the thickness of the helical arms of the first double helix structure 1 is equal to the thickness of the connecting rod 6. When the cross-sectional shape is circular, the radius of the helical arms of the first double helix structure 1 is equal to the radius of the connecting rod 6. It should be noted that the cross-sectional shapes of the first double helix structure 1 and the connecting rod 6 can also be set to be different, as long as they can ensure a stable connection.

[0073] Optionally, the cross-sectional shape of the first double helix structure 1 may be rectangular, circular, elliptical or diamond-shaped.

[0074] Exemplarily, the cross-sectional shapes of the first, second, third, and fourth double helical structures and the connecting rod 6 are identical rectangular shapes.

[0075] In a preferred embodiment of manufacturing materials, the first double helix structure 1, the second double helix structure 2, the third double helix structure 3, the fourth double helix structure 4, and the connecting rod 6 are all composed of metal conductors. Using metal conductors to form the first, second, third, and fourth double helix structures ensures that the omnidirectional circularly polarized antenna can receive and transmit radio waves. Using metal conductors to form the connecting rod 6 connects the first and third double helix structures, and the second and fourth double helix structures, thereby cascading the different double helix structures. This also reduces the overall size of the omnidirectional circularly polarized antenna, making the structure more compact.

[0076] Optimized: The number of spiral turns N1 of the first double helix structure 1 is 2. Based on the symmetry between the first and second double helix structures, the number of spiral turns of the second double helix structure 2 is also 2. The number of spiral turns N2 of the third double helix structure 3 is 1. Based on the symmetry between the third and fourth double helix structures, the number of spiral turns of the fourth double helix structure 4 is also 1.

[0077] For example: the helical radius r_helix of the first double helix structure 1 is 1.5 mm; the pitch between turns of the first double helix structure 1 is pitch = 9 mm; the helical radius r_loop of the third double helix structure 3 is 9 mm; the pitch between turns of the third double helix structure 3 is pitch_loop = 10.25 mm.

[0078] A preferred embodiment of the connecting rod 6 is as follows: the connecting rod 6 is a rectangular straight rod, perpendicular to the axis of the first double helix structure 1, that is, the extending direction of the connecting rod 6 is perpendicular to the axis of the first double helix structure 1; the two spiral arms of the first double helix structure 1 are each connected to the two spiral arms of the third double helix structure 3 via a connecting rod 6, and the extending directions of the two connecting rods 6 connecting the first double helix structure 1 and the third double helix structure 3 are collinear; the two spiral arms of the second double helix structure 2 are each connected to the two spiral arms of the fourth double helix structure 4 via a connecting rod 6, and the extending directions of the two connecting rods 6 connecting the second double helix structure 2 and the fourth double helix structure 4 are collinear; the connecting rod 6 connected to the first double helix structure 1 and the connecting rod 6 connected to the second double helix structure 2 are symmetrical about the feeding structure 5. This achieves the cascade of the first and third double helix structures and the cascade of the second and fourth double helix structures.

[0079] A preferred embodiment of the feeding structure 5: the feeding structure 5 is composed of two metal blocks 51 and a feeding plate 52; the two metal blocks 51 and the feeding plate 52 form an I-shaped structure; the two ends of one metal block 51 in the extension direction are respectively connected to the two spiral arms of the first double helix structure 1, and the two ends of the other metal block 51 in the extension direction are respectively connected to the two spiral arms of the second double helix structure 2; the extension direction of the metal block 51 is perpendicular to the axis of the first double helix structure 1; the two metal blocks 51 are coplanar with the four connecting rods 6.

[0080] For example: Figure 2 As shown, the metal block 51 is a rectangular structure extending in the left-right direction; the central area of ​​the lower surface of the metal block 51 located at the top is connected to the upper end of the square feeding plate 52, the right end of its front surface is connected to one spiral arm of the first double helix structure 1, and the left end of its rear surface is connected to the other spiral arm of the first double helix structure 1; the central area of ​​the upper surface of the metal block 51 located at the bottom is connected to the lower end of the square feeding plate 52, the left end of its front surface is connected to one spiral arm of the second double helix structure 2, and the right end of its rear surface is connected to the other spiral arm of the second double helix structure 2; the largest surface of the feeding plate 52 is parallel to the front surface of the metal block 51.

[0081] Specifically: Figure 3 |S11| is the omnidirectional circularly polarized antenna. From this figure, we can see that the antenna resonates around 2.4 GHz, and the -10 dB bandwidth covers 2.37 GHz to 2.44 GHz (2.9%). Figure 4 This is the horizontal plane axial ratio diagram of the omnidirectional circularly polarized antenna. As shown in the figure, the axial ratio of the antenna remains less than 3dB in the horizontal plane. Therefore, the antenna can be considered as an omnidirectional circularly polarized antenna (in the XOY plane). Figure 5This is the radiation pattern of an omnidirectional circularly polarized antenna. In addition to being able to see that the radiation of the antenna is omnidirectional, it can also be observed that the radiation pattern of the antenna is extremely symmetrical: the pattern presents a symmetrical horizontal "8" shape in the vertical plane, and the antenna gain in each direction in the horizontal plane is basically the same, and the omnidirectional gain value ranges from 1.78dB to 2.26dB.

[0082] Example 2

[0083] A cascade antenna provided in an embodiment of the present invention includes an omnidirectional circularly polarized antenna, which is cascaded in the axial direction, that is, cascaded in the vertical direction. The specific structure of the omnidirectional circularly polarized antenna refers to Example 1. Since the cascade antenna adopts all the technical solutions in Example 1, it has at least the beneficial effects brought by the technical solutions in Example 1, which will not be repeated here.

[0084] For example: the omnidirectional circularly polarized antenna of Example 1 is expanded as a basic unit, by cascading a small double helix structure at one end of the third double helix structure 3 away from the first double helix structure 1, and cascading a large double helix structure at one end of the small double helix structure away from the third double helix structure 3, wherein the small double helix structure is a connection combination composed of another group of first double helix structures 1 and second double helix structures 2, and the large double helix structure is a double helix structure with the same shape as the third double helix structure 3, and the cascading is achieved by a connecting rod 6 made of a metal conductor. The cascading method refers to the cascading of the first double helix structure 1 and the third double helix structure 3 in Example 1, thereby achieving the purpose of increasing the gain.

[0085] Example 3

[0086] An antenna array provided in an embodiment of the present invention includes N omnidirectional circularly polarized antennas, where N is an integer greater than or equal to 2, and the N omnidirectional circularly polarized antennas are arranged in a direction perpendicular to the axis, that is, multiple omnidirectional circularly polarized antennas are arranged in the horizontal direction. The specific structure of the omnidirectional circularly polarized antenna refers to Example 1. Since the antenna array adopts all the technical solutions in Example 1, it has at least the beneficial effects brought by the technical solutions in Example 1, which will not be repeated here.

[0087] Exemplary: multiple omnidirectional circularly polarized antennas are arrayed to obtain a high-gain omnidirectional circularly polarized array, an end-fire circularly polarized array, etc.

[0088] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An omnidirectional circularly polarized antenna, characterized in that: include: a first double helix structure, a second double helix structure, a third double helix structure, a fourth double helix structure, a feeding structure, and a connecting rod; The helical radius of the first double helical structure is smaller than the helical radius of the third double helical structure; One end of the first double helix structure is coaxially connected to one end of the second double helix structure through the feeding structure, and the other end is coaxially connected to the third double helix structure through the connecting rod; The other end of the second double helix structure is coaxially connected to the fourth double helix structure via the connecting rod; The first double helix structure and the third double helix structure are symmetrical with respect to the feeding structure and the second double helix structure and the fourth double helix structure; The sum of the helical lengths of the first double helical structure and the second double helical structure is 0.5 ; The helical lengths of the third double helical structure and the fourth double helical structure are both 0.5 ; The feeding structure includes two metal blocks and a feeding plate; The two metal blocks and one feed plate form an I-shaped structure; Two ends of one metal block in the extension direction are respectively connected to the two spiral arms of the first double helix structure, and two ends of another metal block in the extension direction are respectively connected to the two spiral arms of the second double helix structure; The extending direction of the metal block is perpendicular to the axis of the first double helix structure.

2. The omnidirectional circularly polarized antenna according to claim 1, wherein: The cross-sectional shapes of the first double helical structure and the third double helical structure are the same; The first double helical structure and the connecting rod have the same cross-sectional shape.

3. The omnidirectional circularly polarized antenna according to claim 2, wherein: The cross-sectional shape of the first double helix structure is rectangular, circular, elliptical or diamond-shaped.

4. The omnidirectional circularly polarized antenna according to claim 1, wherein: The first double helix structure, the second double helix structure, the third double helix structure, the fourth double helix structure and the connecting rod are all made of metal conductors.

5. The omnidirectional circularly polarized antenna according to claim 1, wherein: The number of helical turns of the first double helix structure N1=2; The number of helical turns N2 of the third double helix structure is 1.

6. The omnidirectional circularly polarized antenna according to any one of claims 1 to 5, characterized in that: The helical radius of the first double helix structure r_helix=1.5 mm; The pitch of the turns of the first double helix structure is pitch=9mm; The spiral radius of the third double helix structure r_loop=9mm; The pitch_loop of the third double helix structure is 10.25 mm.

7. The omnidirectional circularly polarized antenna according to any one of claims 1 to 5, characterized in that: The connecting rod is perpendicular to the axis of the first double helix structure; The two spiral arms of the first double helix structure are respectively connected to the two spiral arms of the third double helix structure through one connecting rod; The two spiral arms of the second double helix structure are respectively connected to the two spiral arms of the fourth double helix structure through one connecting rod.

8. A cascade antenna, characterized in that: include: An omnidirectional circularly polarized antenna according to any one of claims 1 to 7; The omnidirectional circularly polarized antennas are cascaded in an axial direction.

9. An antenna array, characterized in that: include: N omnidirectional circularly polarized antennas according to any one of claims 1 to 7, wherein N is an integer greater than or equal to 2; The N omnidirectional circularly polarized antennas are arranged in a direction perpendicular to the axial direction.

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