A single-layer broadband omnidirectional circularly polarized antenna

Abstract

The application belongs to the technical field of wireless communication, and provides a single-layer broadband omnidirectional circularly polarized antenna, which comprises a metal patch radiation structure, a dielectric substrate, a metal ground plate and a coaxial feeding probe; wherein the metal patch radiation structure is composed of a central large square patch 1-1, a small rectangular patch 1-2 and an L-shaped patch 1-3; through the structure design, the coaxial probe is fed in the center of the central large square patch to excite the current diverging to the four directions, so that the vertical omnidirectional radiation characteristic (current source radiation) is realized; then four rotationally symmetrical L-shaped patches are loaded at four corners to introduce the annular current (magnetic current source radiation), so that the horizontal omnidirectional radiation characteristic is realized; at the same time, the vertical omnidirectional radiation and the horizontal omnidirectional radiation present a time phase difference of 90°, so that the omnidirectional circularly polarized radiation characteristic is realized in the far field. In summary, the application realizes the broadband omnidirectional circularly polarized radiation, and has the characteristics of simple structure, wide band and high gain.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wireless communication, and relates to an omnidirectional circularly polarized antenna, in particular to a single-layer broadband omnidirectional circularly polarized antenna. BACKGROUND

[0002] In modern wireless communication systems, as a component for receiving and transmitting electromagnetic waves, the antenna has been closely related to our life, such as navigation, television, radar, radio, satellite and other wireless communication systems that need electromagnetic waves to transmit information, and the performance of the antenna will directly affect the communication quality. At the same time, with the development of wireless communication, a single property antenna has been increasingly difficult to meet our needs, and the form and performance of the antenna are different in different environments, which leads to great differences in the structure of modern antennas.

[0003] The omnidirectional circularly polarized antenna has the characteristics of both omnidirectional antenna and circularly polarized antenna, and can transmit and receive electromagnetic wave signals in any direction in a horizontal plane at a certain angle, and can also radiate and receive circularly polarized waves. At present, there are mainly three methods to realize the omnidirectional circularly polarized antenna: the first method is to feed circularly polarized waves through a circular polarizer on an omnidirectional antenna or to load a parasitic unit to change the polarization characteristics of the radiated wave, this kind of antenna has good omnidirectional coverage, but the size is large, the profile is high, it is difficult to realize miniaturization and the processing is complex; the second method is to feed each antenna unit through a suitable feed network to realize omnidirectional circular polarization, this kind of antenna is easy to manufacture and process, but the requirement for the feed structure is relatively high, and the design of the feed network is complex; the third method is to combine omnidirectional antennas that generate vertical linear polarization components and horizontal linear polarization components, this kind of antenna is easy to realize wideband, but it is not easy to meet the actual demand in application, and the antenna design is also complex. At present, it is still a challenge to design a single-layer omnidirectional circularly polarized antenna with simple structure. SUMMARY

[0004] The present application aims to provide a single-layer broadband omnidirectional circularly polarized antenna, which has the advantages of simple antenna structure and excellent performance, and has a wide application prospect.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] A single-layer broadband omnidirectional circularly polarized antenna, comprising: a metal patch radiation structure 1, a dielectric substrate 2, a metal ground plate 3, a coaxial feed probe 4 and a short-circuit probe 5; wherein the metal patch radiation structure 1 is arranged on the upper surface of the dielectric substrate 2, and the metal ground plate 3 is arranged on the lower surface of the dielectric substrate 2.

[0007] Characterized in that:

[0008] The metal patch radiation structure 1 is a 90° central rotationally symmetrical structure, which is composed of a central large square patch 1-1, eight small rectangular patches 1-2 and four L-shaped patches 1-3; the central large square patch is arranged at the center position and has a center-loaded circular ring-shaped slot, the eight small rectangular patches 1-2 and the four L-shaped patches 1-3 are arranged around the central large square patch 1-1, the small rectangular patches 1-2 are arranged in pairs and correspond to the four edges of the central large square patch 1-1, and the L-shaped patches 1-3 correspond to the four corners of the central large square patch 1-1; the wide edge of the small rectangular patch 1-2 is opposite to the edge of the central large square patch 1-1, and the long edge of the small rectangular patch 1-2 is opposite to the edge of the square patch 1-3-1 of the L-shaped patch 1-3, and the long edge of the small rectangular patch 1-2 is flush with the edge of the central large square patch 1-1.

[0009] The coaxial feed probe 4 penetrates the dielectric substrate 2, the top end is connected to the central large square patch 1-1 for feeding, and the feeding point is located at the center of the central large square patch; the bottom end is connected to the metal ground plate 3.

[0010] Further, the L-shaped patch 1-3 is composed of a small square patch 1-3-1, a large rectangular patch 1-3-2 and an L-shaped branch 1-3-3; one side of the large rectangular patch 1-3-2 is spliced to one end of the small square patch 1-3-1 away from the central large square patch 1-1, and the center of the large rectangular patch 1-3-2 and the small square patch 1-3-1 are located on the extension line of the diagonal of the large square patch 1-1; an L-shaped branch 1-3-3 is vertically loaded at the middle position of the other side of the large rectangular patch 1-3-2, and the short branch of the L-shaped branch 1-3-3 points to the small square patch 1-3-1; the small square patch 1-3-1 is connected to the metal ground plate 3 through the short probe 5; as an optimal choice, the probe is loaded on the small square patch 1-3-1 close to the small rectangular patch 1-2 and away from the large rectangular patch 1-3-2 and the corner of the central large square patch 1-1.

[0011] Further, the distance between the small rectangular patch 1-2 and the adjacent central large square patch 1-1 is g1, and the distance between the small rectangular patch 1-2 and the adjacent L-shaped patch 1-3 is g1.

[0012] Further, the length of the central large square patch 1-1 is l1, the long edge of the small rectangular patch 1-2 is l2, the length of the small square patch 1-3-1 of the L-shaped patch is l3, l3 = l2, and l2 < l1.

[0013] From the working principle:

[0014] The radiation of the current source and the magnetic current source is omnidirectional radiation, the electric field of the parallel placed current source and the magnetic current source in a specific direction in a far zone is orthogonal, if the current source and the magnetic current source can ensure 90° time phase difference, omnidirectional circular polarization radiation characteristics can be realized. Based on the principle, the current source and the magnetic current source which alternately radiate are generated by adopting the special-shaped patch in the application, and the 90° phase difference in space is ensured by parallel arrangement, the omnidirectional circular polarization characteristics can be realized by reasonably optimizing the size and making the current source and the magnetic current source alternately radiate in a period. Specifically, the coaxial probe is fed in the center of the single-layer square microstrip patch to excite the current which radiates to the four directions, so that the vertical omnidirectional radiation characteristics (current source radiation) are realized; the L-shaped patch with four rotationally symmetrical L-shaped branches is loaded on the four corners of the original square microstrip patch on the structure, and the annular current (magnetic current source radiation) is further introduced, which can realize the horizontal omnidirectional radiation characteristics. The annular current on the L-shaped patch with four rotationally symmetrical L-shaped branches and the divergent current on the square microstrip patch alternately realize in a period, so that the vertical omnidirectional radiation and the horizontal omnidirectional radiation present 90° time phase difference, and the omnidirectional circular polarization radiation characteristics are realized in a far zone. The rectangular patch located on the four edges of the square patch is used to optimize the coupling strength of the square patch and the L-shaped patch with L-shaped branches, and the annular gap on the square microstrip patch and the short-circuit probe loaded on the L-shaped patch with L-shaped branches are used to improve the matching.

[0015] In summary, the application has the following advantages:

[0016] The application provides a single-layer broadband omnidirectional circularly polarized antenna, which realizes broadband omnidirectional circularly polarized radiation by reasonably arranging the positions and shapes of the patch structures. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 is a top view of a single-layer broadband omnidirectional circularly polarized antenna according to the application.

[0018] Figure 2 Fig. 2 is a side view of the single-layer broadband omnidirectional circularly polarized antenna according to the application.

[0019] Figure 3 Fig. 3 is a top view of a square patch in an embodiment of the application.

[0020] Figure 4 Fig. 4 is a surface current distribution diagram of the antenna when the square patch in the embodiment of the application works at 7.9 GHz.

[0021] Figure 5A surface current distribution diagram of a single-layer broadband omnidirectional circularly polarized antenna in an embodiment of the present application operating at 7.9 GHz.

[0022] Figure 6 An antenna return loss diagram and a gain diagram of a single-layer broadband omnidirectional circularly polarized antenna in an embodiment of the present application.

[0023] Figure 7 An axial ratio diagram of a single-layer broadband omnidirectional circularly polarized antenna in an embodiment of the present application at θ = 30°.

[0024] Figure 8 A two-dimensional radiation pattern diagram of a single-layer broadband omnidirectional circularly polarized antenna in an embodiment of the present application operating at 7.9 GHz. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions and technical effects of the present application more complete and clear, the present application will be further described in detail below in combination with the drawings and embodiments.

[0026] The present embodiment provides a single-layer broadband omnidirectional circularly polarized antenna, which has a structure as shown in Figure 1 , Figure 2 includes a metal patch radiation structure 1, a dielectric substrate 2, a metal ground plate 3, a coaxial feed probe 4 and a short-circuit probe 5; wherein the metal patch radiation structure 1 is arranged on the upper surface of the dielectric substrate 2, and the metal ground plate 3 is arranged on the lower surface of the dielectric substrate 2.

[0027] Further, the metal patch radiation structure 1 has a 90° central rotational symmetry structure, which is composed of a central large square patch 1-1, eight small rectangular patches 1-2 and four L-shaped patches 1-3; the central large square patch is arranged at the center position and has a center-loaded circular ring-shaped gap, the eight small rectangular patches 1-2 and the four L-shaped patches 1-3 are arranged around the central large square patch 1-1, the small rectangular patches 1-2 are arranged in pairs and correspond to the four edges of the central large square patch 1-1, and the L-shaped patches 1-3 are arranged corresponding to the four corners of the central large square patch 1-1.

[0028] The L-shaped patch 1-3 is composed of a small square patch 1-3-1, a large rectangular patch 1-3-2 and an L-shaped branch 1-3-3. One side of the large rectangular patch 1-3-2 is spliced to one end of the small square patch 1-3-1 away from the center large square patch 1-1, and the center of the large rectangular patch 1-3-2 and the center of the small square patch 1-3-1 are located on the extension line of the diagonal of the large square patch 1-1. The middle position of the other side of the large rectangular patch 1-3-2 is vertically loaded with the L-shaped branch 1-3-3, and the short branch of the L-shaped branch 1-3-3 points to the small square patch 1-3-1. The small square patch 1-3-1 is connected to the metal ground plate 3 through a short-circuit probe 5. As an optimal choice, the probe is loaded on the small square patch 1-3-1 close to the small rectangular patch 1-2 and away from the corner of the large rectangular patch 1-3-2 and the center large square patch 1-1.

[0029] The wide side of the small rectangular patch 1-2 is opposite to the side of the center large square patch 1-1 with a spacing of g1, and the long side of the small rectangular patch 1-2 is opposite to the side of the square patch 1-3-1 in the L-shaped patch 1-3 with a spacing of g1. The long side of the small rectangular patch 1-2 (adjacent to the long side of the square patch 1-3-1 in the L-shaped patch 1-3) is flush with the side of the center large square patch 1-1.

[0030] The coaxial feed probe 4 penetrates the dielectric substrate 2, and its top end is connected to the center large square patch 1-1 for feeding, and the feeding point is located at the center of the center large square patch. The bottom end is connected to the metal ground plate 3.

[0031] Specifically, in this embodiment: the dielectric substrate 2 is F4BTM-2 board material with a dielectric constant of 4.4, a thickness h = 4 mm, and a side length W = 52 mm; the coaxial feeding probe 4 has a diameter d2 = 0.8 mm, and the short-circuit probe 5 has a diameter d3 = 0.2 mm; the inner circle radius of the annular shape on the large square patch 1-1 is r = 1.7 mm, and the outer circle radius is r1 = 3 mm; the side length of the large square patch 1-1 is l1 = 15 mm, the distance between the large square patch 1-1 and the small rectangular patch 1-2 is g1 = 2 mm, the long side of the small rectangular patch 1-2 is l2 = 6 mm, the short side is w2 = 2.5 mm, and the distance between the small rectangular patches on the same side of the large square patch 1-1 is g2 = 10 mm; the distance between the small rectangular patch 1-2 and the L-shaped patch 1-3 is also g1 = 2 mm, the side length of the small square patch 1-3-1 in the L-shaped patch 1-3 is l3 = l2 = 6 mm, the long side of the large rectangular patch 1-3-2 is l4 = 5 mm, the short side is w4 = 4 mm, the L-shaped branch 1-3-3 is located on the long side of the large rectangular patch 1-3-2, and the distance from the long side edge is g3 = 2.5 mm; the long branch of the L-shaped branch 1-3-3 has a length l5 = 5 mm and a width w5 = 1 mm, and the short branch has a length l6 = 3 mm and a width w6 = 0.7 mm; the top end of the short-circuit probe 5 contacts the L-shaped patch 1-3, and the bottom end contacts the metal ground layer 3; the distance from the two sides of the small square patch 1-3-1 in the L-shaped patch is g4 = 0.5 mm and g5 = 0.7 mm, respectively.

[0032] As shown in Figure 3 , the antenna structure when the substrate upper layer has only the middle square patch is shown, as shown in Figure 4 , the surface current distribution diagram of the antenna working at 7.9 GHz is shown, and it can be seen that the current on the square patch is divergent, thereby forming vertical omnidirectional radiation.

[0033] As shown in Figure 5 , the surface current distribution diagram of the single-layer wideband omnidirectional circularly polarized antenna of the embodiment working at 7.9 GHz is shown, and it can be seen that at 0 time, the annular current on the L-shaped patch with L-shaped branches around is dominant, which produces radiation of a magnetic current source; at a quarter of the period, the divergent current on the center patch is dominant, which produces radiation of an electric current source; at half of the period, the annular current is dominant, which produces radiation of a magnetic current source, but the current direction is opposite to that at 0 time; at three-quarters of the period, the divergent current on the center patch is dominant, which produces radiation of an electric current source, but the current direction is opposite to that at half of the period; it is the alternating radiation of the electric current source and the magnetic current source that makes the antenna achieve circular polarization characteristics in the far field.

[0034] As shown in Figure 6 , the antenna return loss diagram and the gain diagram of the single-layer wideband omnidirectional circularly polarized antenna of the embodiment are shown, as shown in Figure 7The axial ratio diagram of the single-layer broadband omnidirectional circularly polarized antenna of the embodiment at θ=30° is shown as follows: Figure 8 The two-dimensional radiation pattern of the single-layer broadband omnidirectional circularly polarized antenna of the embodiment when working at 7.9 GHz is shown as follows: Figure 6 And Figure 7 It can be seen that the reflection coefficient of the antenna of the present application in the frequency band of 7.03-8.62 GHz is less than -10, and the impedance bandwidth of -10 dB can reach 20.3%; the axial ratio coefficient of the antenna of the present application in the frequency band of 7.39-8.56 GHz is less than 3, and the axial ratio bandwidth of 3 dB can reach 14.7%; the maximum gain of the antenna of the present application in the working frequency band can reach 4.3dBi; from Figure 8 It can be seen that the antenna of the present application is omnidirectional in the horizontal direction at θ=30°, and is a right-handed circularly polarized antenna.

[0035] In summary, the single-layer broadband omnidirectional circularly polarized antenna provided by the present application has good omnidirectional circularly polarized radiation, and the antenna structure is simple.

[0036] The above is only a specific embodiment of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically stated; all features disclosed, or steps in all methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A single-layer broadband omnidirectional circularly polarized antenna, comprising: The device comprises a metal patch radiating structure (1), a dielectric substrate (2), a metal ground plane (3), and a coaxial feed probe (4); wherein the metal patch radiating structure is disposed on the upper surface of the dielectric substrate, and the metal ground plane is disposed on the lower surface of the dielectric substrate; characterized in that: The metal patch radiation structure (1) has a 90° central rotational symmetry structure, consisting of a central large square patch (1-1), eight small rectangular patches (1-2), and four L-shaped patches (1-3). The central large square patch is located at the center and has a circular gap at its center. The eight small rectangular patches (1-2) and four L-shaped patches (1-3) are arranged around the central large square patch (1-1). The small rectangular patches are arranged in pairs and correspond to the four sides of the central large square patch. The pairs of small rectangular patches are arranged perpendicular to each other. The L-shaped patches are arranged at the four corners of the central large square patch. The wide side of the small rectangular patch (1-2) is aligned with the side of the central large square patch (1-1), and the long side is aligned with the L-shaped patch (1-3). The long side of the small rectangular patch is flush with the edge of the central large square patch (1-1). The coaxial feed probe (4) passes through the dielectric substrate (2), its top end is connected to the central large square patch (1-1) for power supply, and the power supply point is located at the center of the central large square patch, and its bottom end is connected to the metal ground plate (3). The L-shaped patch (1-3) is composed of a small square patch (1-3-1), a large rectangular patch (1-3-2), and an L-shaped branch (1-3-3). One long side of the large rectangular patch (1-3-2) is joined to the end of the small square patch furthest from the center of the large square patch. The centers of both the large rectangular patch (1-3-2) and the small square patch (1-3-1) are located on the extension of the diagonal of the large square patch (1-1). On the other side of the long side, a vertical L-shaped branch (1-3-3) is loaded at the middle position, and the short branch of the L-shaped branch (1-3-3) points to the small square patch (1-3-1); the small square patch (1-3-1) is connected to the metal ground plate (3) through a short-circuit probe (5), and the short-circuit probe is loaded on the small square patch (1-3-1) close to the small rectangular patch (1-2) and away from the corner of the large rectangular patch (1-3-2) and the central large square patch (1-1).

2. The single-layer broadband omnidirectional circularly polarized antenna according to claim 1, characterized in that, The spacing between the small rectangular patch (1-2) and the adjacent large central square patch (1-1) is g1, and the spacing between the small rectangular patch (1-2) and the adjacent L-shaped patch (1-3) is g1.

3. The single-layer broadband omnidirectional circularly polarized antenna according to claim 1, characterized in that, The side length of the large square patch (1-1) in the center is l1, the long side of the small rectangular patch (1-2) is l2, and the side length of the small square patch (1-3-1) in the L-shaped patch is l3, where l3 = l2 and l2 < l1.

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