A dual-band omnidirectional circularly polarized antenna with single-feed port

Abstract

The application discloses a single-port-fed dual-frequency omnidirectional circularly polarized antenna, which comprises two vertically intersecting +45-degree first dielectric substrates and -45-degree second dielectric substrates. The upper surface of the +45-degree first dielectric substrate is printed with two concentric zero-phase-shift magnetic rings, wherein the outer ring is a zero-phase-shift low-frequency magnetic ring, and the inner ring is a zero-phase-shift high-frequency magnetic ring; the upper and lower surfaces of the -45-degree second dielectric substrate are respectively printed with two arms of a dual-frequency dipole, the dual-frequency dipole is composed of a first low-frequency dipole and a first high-frequency dipole and is connected through a metal column. Signals enter from a port, and the first low-frequency dipole arm, the first high-frequency dipole arm and the zero-phase-shift low-frequency magnetic ring and the high-frequency magnetic ring are simultaneously and in-phase excited through two microstrip feed lines printed on the upper and lower surfaces of the -45-degree second dielectric substrate, so that dual-frequency circularly polarized radiation is realized. The designed low-frequency magnetic ring and the high-frequency magnetic ring can realize good omnidirectional radiation of the antenna. The antenna works at two frequency bands of 2.45 GHz and 5.8 GHz, and good omnidirectional circularly polarized radiation is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication and antenna design, more particularly, it relates to a single-port-fed dual-band omnidirectional circularly polarized antenna. BACKGROUND

[0002] As one of the most important components in wireless communication systems, antennas bear the core function of converting electrical signals and spatial electromagnetic waves, and are widely used in communication, navigation and radar fields. With the rapid development of wireless communication technology, the performance, size and multifunctionality of antennas are constantly improving. In today's high-speed and complex communication environment, traditional linearly polarized antennas are difficult to meet the demand of stable and efficient communication due to polarization mismatch causing signal loss. Therefore, circularly polarized antennas with high anti-interference ability and excellent polarization matching performance have been widely researched and applied.

[0003] In recent years, the rapid popularization of wireless local area network (WLAN), Bluetooth and industrial, scientific and medical (ISM) band communication technology has put forward the requirement of dual-band operation for antennas. In the two main frequency bands of 2.45GHz and 5.8GHz, although the traditional multi-antenna scheme can achieve multi-frequency coverage, it generally needs a feed network to excite two antennas of different frequency bands, which has complex structure, high cost and large power loss, and has gradually been difficult to meet the miniaturization, low power consumption and high efficiency requirements of modern communication devices. Therefore, the research and development of simple structure and excellent performance dual-band antennas have become the focus of the current wireless communication field.

[0004] Omnidirectional circularly polarized antennas have unique advantages in modern communication systems due to their ability to uniformly radiate circularly polarized waves in the azimuth plane. It can effectively reduce the interference caused by multipath reflection and polarization mismatch during signal transmission, significantly improving communication reliability. In addition, omnidirectional circularly polarized antennas can maintain stable signal transmission in complex environments by simplifying the system structure, and are widely used in wireless communication, navigation and positioning, Internet of Things, aerospace and other fields.

[0005] Under this background, there is an urgent need to design a single-port-fed dual-band omnidirectional circularly polarized antenna to solve the above problems, and a single-port-fed dual-band omnidirectional circularly polarized antenna has emerged as the times require. SUMMARY

[0006] The purpose of the present application is to provide a single-port-fed dual-band omnidirectional circularly polarized antenna to solve at least one technical problem existing in the prior art.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A single-port-fed dual-band omnidirectional circularly polarized antenna comprises a first dielectric substrate and a second dielectric substrate, a low-frequency magnetic ring and a high-frequency magnetic ring are printed on the upper surface of the first dielectric substrate, the high-frequency magnetic ring is located inside the low-frequency magnetic ring, a first low-frequency dipole arm and a first high-frequency dipole arm are printed on the upper and lower surfaces of the second dielectric substrate respectively, the first low-frequency dipole arm and the first high-frequency dipole arm are connected by a metal column, a microstrip transmission line is printed on the upper and lower surfaces of the second dielectric substrate, and the microstrip transmission line is used to connect a port, the first low-frequency dipole arm, the low-frequency magnetic ring and the high-frequency magnetic ring, the port is located at the starting end of the microstrip transmission line.

[0009] As a preferred embodiment of the present application, the first dielectric substrate is a +45° dielectric substrate, the second dielectric substrate is a -45° dielectric substrate, the low-frequency magnetic ring is located on the outer ring of the first dielectric substrate, the high-frequency magnetic ring is located on the inner ring of the first dielectric substrate, and the low-frequency magnetic ring and the high-frequency magnetic ring are concentric zero-phase-shift magnetic rings.

[0010] As a preferred embodiment of the present application, a Y structure and a first strip structure are arranged on the low-frequency magnetic outer ring, the Y structure is in the shape of Y, the first strip structure is in the shape of an arc, the Y structure is equivalent to a capacitor element, and the first strip structure is equivalent to an inductor element.

[0011] As a preferred embodiment of the present application, a T structure and a second strip structure are arranged on the high-frequency magnetic ring, the T structure is in the shape of T, the second strip structure is in the shape of an arc, the T structure is equivalent to a capacitor element, and the second strip structure is equivalent to an inductor element.

[0012] As a preferred embodiment of the present application, a first recess is formed on the first dielectric substrate, a second recess is formed on the second dielectric substrate, the first recess and the second recess are connected by clamping, and the first recess and the second recess are used to vertically connect the first dielectric substrate and the second dielectric substrate.

[0013] As a preferred embodiment of the present application, a second low-frequency dipole arm connected with a pair of E-shaped patches and a rectangular patch is also printed on one side of the second dielectric substrate, the first low-frequency dipole arm and the second low-frequency dipole arm are the same in shape.

[0014] The rectangular patch comprises a first rectangular patch, a second rectangular patch, a third rectangular patch and a fourth rectangular patch, the first rectangular patch is a low-impedance microstrip line, the second rectangular patch is a high-impedance microstrip line, a first circular hole is etched on the first rectangular patch, the third rectangular patch and the fourth rectangular patch are equal in size and the same in shape, the third rectangular patch and the fourth rectangular patch are symmetrical about the second rectangular patch, and the width of the first rectangular patch is greater than the width of the second rectangular patch.

[0015] As a preferred embodiment of the present application, a second high-frequency dipole arm of a gradually changing rectangular patch is printed on the other side of the second dielectric substrate, a fifth rectangular patch and a sixth rectangular patch are arranged on the second high-frequency dipole arm, a second circular hole is etched on the fifth rectangular patch, the fifth rectangular patch is a low-impedance microstrip line, the sixth rectangular patch is a high-impedance microstrip line, the shape of the second high-frequency dipole arm is the same as that of the first high-frequency dipole arm, and the width of the fifth rectangular patch is greater than that of the sixth rectangular patch.

[0016] As a preferred embodiment of the present application, the number of microstrip transmission lines is two, the starting positions of the microstrip transmission lines are connected with the ports, the middle positions of the microstrip transmission lines are connected with the low-frequency magnetic loop and the high-frequency magnetic loop, and the end positions of the microstrip transmission lines are connected with the first low-frequency dipole arm and the second low-frequency dipole arm.

[0017] As a preferred embodiment of the present application, the number of metal columns is two, and the two metal columns are embedded on the second dielectric substrate.

[0018] Compared with the prior art, the present application provides a single-port-fed dual-frequency omnidirectional circularly polarized antenna, which has the following beneficial effects:

[0019] 1. The two microstrip transmission lines designed in the present application can simultaneously and in phase excite the first low-frequency dipole arm, the first high-frequency dipole arm, the low-frequency magnetic loop with zero phase shift, and the high-frequency magnetic loop with zero phase shift, thereby realizing single-port feeding, reducing signal loss, and improving antenna gain.

[0020] 2. The present application realizes a single current flow direction by designing two low-frequency magnetic loops and high-frequency magnetic loops with zero phase shift, and the designed low-frequency dipoles can adjust the coupling relationship, thereby well solving the problem of directional diagram distortion.

[0021] 3. The present application simultaneously and in phase excites two low-frequency and high-frequency dipoles and two low-frequency and high-frequency magnetic loops, and the two orthogonal component polarizations generated due to the spatial difference realize a 90° phase difference, and the antenna is omnidirectionally radiated, thereby having the performance of omnidirectional circular polarization. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic view of an antenna structure of the present application;

[0023] Figure 2 is a side view of the antenna structure of the present application;

[0024] Figure 3 is a front view of a second dielectric substrate;

[0025] Figure 4 is a top view of a first dielectric substrate;

[0026] Figure 5is a simulation S11 parameter curve diagram of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application;

[0027] Figure 6 is a simulation left-handed and right-handed gain curve diagram of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application;

[0028] Figure 7 is a simulation axial ratio parameter curve diagram of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application;

[0029] Figure 8 is a simulation result diagram of an H-plane pattern of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application at a 2.45GHz frequency;

[0030] Figure 9 is a simulation result diagram of an E-plane pattern of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application at a 2.45GHz frequency;

[0031] Figure 10 is a simulation result diagram of an H-plane pattern of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application at a 5.8GHz frequency;

[0032] Figure 11 is a simulation result diagram of an E-plane pattern of a single-port fed dual-frequency omnidirectional circularly polarized antenna of the application at a 5.8GHz frequency;

[0033] In the figure: 1, first low-frequency dipole arm; 1a, first rectangular patch; 1b, second rectangular patch; 1c, third rectangular patch; 1d, fourth rectangular patch; 1e, first circular hole; 1f, second low-frequency dipole arm; 2, first high-frequency dipole arm; 2a, fifth rectangular patch; 2b, sixth rectangular patch; 2c, second circular hole; 2d, second high-frequency dipole arm; 3, low-frequency magnetic ring; 3a, Y structure; 3b, first bar structure; 4, high-frequency magnetic ring; 4a, T structure; 4b, second bar structure; 5, port; 6, microstrip transmission line; 7, metal column; 8, second dielectric substrate; 9, first dielectric substrate; 11, first groove; 12, second groove. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be apparently and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application.

[0035] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0036] Please refer to Figures 1-4 As shown in the drawings, the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present application comprises a first dielectric substrate 9 and a second dielectric substrate 8, the upper surface of the first dielectric substrate 9 is printed with a low-frequency magnetic ring 3 and a high-frequency magnetic ring 4, the high-frequency magnetic ring 4 is located inside the low-frequency magnetic ring 3, the upper and lower surfaces of the second dielectric substrate 8 are respectively printed with a first low-frequency dipole arm 1 and a first high-frequency dipole arm 2, the first low-frequency dipole arm 1 and the first high-frequency dipole arm 2 are connected by a metal column 7, the upper and lower surfaces of the second dielectric substrate 8 are both printed with a microstrip transmission line 6, the microstrip transmission line 6 is used to connect a port 5, the first low-frequency dipole arm 1, the low-frequency magnetic ring 3 and the high-frequency magnetic ring 4, the port 5 is located at the starting end of the microstrip transmission line 6; the first dielectric substrate 9 is a +45° dielectric substrate, the second dielectric substrate 8 is a -45° dielectric substrate, the low-frequency magnetic ring 3 is located at the outer ring of the first dielectric substrate 9, the high-frequency magnetic ring 4 is located at the inner ring of the first dielectric substrate 9, and the low-frequency magnetic ring 3 and the high-frequency magnetic ring 4 are concentric zero-phase-shift magnetic rings;

[0037] In this embodiment, the two microstrip transmission lines 6 can simultaneously and in phase excite the first low-frequency dipole arm 1, the first high-frequency dipole arm 2 and the zero-phase-shift low-frequency magnetic ring 3 and the zero-phase-shift high-frequency magnetic ring 4, thereby realizing single-port-fed, reducing signal loss and improving antenna gain. By designing two zero-phase-shift low-frequency magnetic rings 3 and high-frequency magnetic rings 4, a single current flow direction is realized, the designed low-frequency dipole can adjust the coupling relationship, and the combination of the two well solves the problem of directional diagram distortion. By simultaneously and in phase exciting the two low-frequency and high-frequency dipoles and the two low-frequency and high-frequency magnetic rings, a 90° phase difference is realized between the two orthogonal component polarizations due to the spatial difference, plus the omnidirectional radiation itself, thereby having the performance of omnidirectional circular polarization.

[0038] The low-frequency magnetic outer ring 3 is provided with a Y-shaped structure 3a and a first strip-shaped structure 3b connected to each other, the Y-shaped structure 3a is in the shape of Y, the first strip-shaped structure 3b is in the shape of an arc line, the Y-shaped structure 3a is equivalent to a capacitor element, and the first strip-shaped structure 3b is equivalent to an inductor element.

[0039] In this embodiment, the first dielectric substrate 9 is a +45° dielectric substrate, and the second dielectric substrate 8 is a -45° dielectric substrate, as shown inFigure 4 As shown in the figure, the low-frequency zero-phase-shift magnetic ring printed on the upper surface of the +45° dielectric substrate provides low-frequency +45° polarization and omnidirectional radiation. The Y-shaped structure 3a designed on the outer ring of the low-frequency magnetic ring 3 is equivalent to a capacitive element, and the first bar-shaped structure 3b is equivalent to an inductive element. The combination of the two can make the current flow in one direction, thereby improving the performance of omnidirectional radiation of the antenna.

[0040] In a specific embodiment, as shown in the figure, the high-frequency zero-phase-shift magnetic ring 4 is printed on the upper surface of the +45° dielectric substrate. Figure 4 As shown in the figure, the high-frequency zero-phase-shift magnetic ring 4 is printed on the upper surface of the +45° dielectric substrate.

[0041] In this embodiment, the high-frequency zero-phase-shift magnetic ring 4 printed on the upper surface of the +45° dielectric substrate provides high-frequency +45° polarization and omnidirectional radiation. The T-shaped structure 4a designed on the outer ring of the high-frequency magnetic ring 4 is equivalent to a capacitive element, and the second bar-shaped structure 4b is equivalent to an inductive element. The combination of the two can make the current flow in one direction, thereby improving the performance of omnidirectional radiation of the antenna.

[0042] In a specific embodiment, as shown in the figure, the high-frequency zero-phase-shift magnetic ring 4 is printed on the upper surface of the +45° dielectric substrate. Figure 1 As shown in the figure, the first recess 11 is formed on the first dielectric substrate 9, and the second recess 12 is formed on the second dielectric substrate 8. The first recess 11 and the second recess 12 are connected to vertically connect the first dielectric substrate 9 and the second dielectric substrate 8. A pair of second low-frequency dipole arms 1f connected by an E-shaped patch and a rectangular patch are printed on one side of the second dielectric substrate 8. The first low-frequency dipole arm 1 and the second low-frequency dipole arm 1f are the same shape.

[0043] The rectangular patch includes a first rectangular patch 1a, a second rectangular patch 1b, a third rectangular patch 1c, and a fourth rectangular patch 1d. The first rectangular patch 1a is a low-impedance microstrip line, and the second rectangular patch 1b is a high-impedance microstrip line. A first circular hole 1e is etched on the first rectangular patch 1a. The third rectangular patch 1c and the fourth rectangular patch 1d are equal in size and shape. The third rectangular patch 1c and the fourth rectangular patch 1d are symmetrical about the second rectangular patch 1b. The width of the first rectangular patch 1a is greater than the width of the second rectangular patch 1b.

[0044] In this embodiment, a pair of "E" shaped patches and a second low frequency dipole arm 1 connected with a rectangular patch are printed on the second dielectric substrate 8 with -45°. A first circular hole 1 is etched on the rectangular patch for facilitating the welding of a metal column 7. The dipole structure can reduce coupling and the influence between different working frequency bands, while it provides low frequency -45° polarization and omni-directional radiation, and generates a fixed 90° phase difference with the magnetic ring corresponding to the working frequency band, thereby having good omni-directional radiation and circular polarization performance.

[0045] In a specific embodiment, as shown in Figure 1 the other side of the second dielectric substrate 8 of the present application is also printed with a second high frequency dipole arm 2d of a gradually changing rectangular patch, the second high frequency dipole arm 2d is provided with a fifth rectangular patch 2a and a sixth rectangular patch 2b, a second circular hole 2c is etched on the fifth rectangular patch 2a, the fifth rectangular patch 2a is a low impedance microstrip line, the sixth rectangular patch 2b is a high impedance microstrip line, the shape of the second high frequency dipole arm 2d is the same as that of the first high frequency dipole arm 2, and the width of the fifth rectangular patch 2a is greater than that of the sixth rectangular patch 2b.

[0046] In this embodiment, a pair of "E" shaped patches and a second low frequency dipole arm 1 connected with a rectangular patch are printed on the second dielectric substrate 8 with -45°. A first circular hole 1 is etched on the rectangular patch for facilitating the welding of a metal column 7. The dipole structure can reduce coupling and the influence between different working frequency bands, while it provides low frequency -45° polarization and omni-directional radiation, and generates a fixed 90° phase difference with the magnetic ring corresponding to the working frequency band, thereby having good omni-directional radiation and circular polarization performance.

[0047] In a specific embodiment, as shown in Figure 3 the number of microstrip transmission lines 6 of the present application is two, the starting position of which is connected with the port 5, the middle position of which is connected with the low frequency magnetic ring 3 and the high frequency magnetic ring 4, and the end position of which is connected with the first low frequency dipole arm 1 and the second low frequency dipole arm 1f.

[0048] In this embodiment, when the signal enters from the port 5, the two microstrip transmission lines 6 can be used for signal transmission, while exciting the antenna.

[0049] In a specific embodiment, as shown in Figure 2 the number of metal columns 7 of the present application is two, and the two metal columns 7 are embedded on the second dielectric substrate 8.

[0050] In this embodiment, the second dielectric substrate 8 is embedded with two metal columns 7 for connecting the first low frequency dipole 1 antenna and the second high frequency dipole 2 antenna, thereby exciting the second high frequency dipole 2 antenna.

[0051] Figure 5The simulation S11 parameter curve diagram of the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present example shows that the frequency band with S parameter lower than -10dB includes two frequency bands of 2.31GHz to 2.55GHz and 5.55GHz to 5.86GHz.

[0052] Figure 6 The simulation left-handed and right-handed gain curve diagram of the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present example shows that the low frequency band is left-handed and the high frequency band is left-handed.

[0053] Figure 7 The simulation axial ratio parameter curve diagram of the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present example shows that the axial ratios of the two frequency bands of 2.45GHz and 5.8GHz are lower than 3db, and the circular polarizations are left-handed.

[0054] Figures 8-9 The simulation low-frequency E-plane and H-plane directional diagram of the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present example.

[0055] Figures 10-11 The simulation high-frequency E-plane and H-plane directional diagram of the single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present example.

[0056] In summary, the single-port-fed dual-frequency omnidirectional circularly polarized antenna adopts a single feeding structure, realizes efficient coverage of the frequency bands of 2.45GHz and 5.8GHz through optimized design, not only saves the design of the feeding network, but also significantly reduces power loss and manufacturing cost, improves the gain and overall efficiency of the antenna, realizes the dual-frequency omnidirectional circularly polarized performance, and effectively solves the problem of high-frequency directional diagram distortion caused by coupling effect of multi-frequency band antennas. The antenna obtains excellent impedance matching and circularly polarized performance under the condition of miniaturized structure, significantly reduces the size of the antenna, overcomes the problems of large size, distorted directional diagram, low gain and complex design of traditional dual-frequency antennas, and provides an innovative solution for the multi-frequency, high-performance and compactness requirements of modern wireless communication equipment.

[0057] The above describes only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical solution and inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A single-port fed dual-frequency omnidirectional circularly polarized antenna, characterized in that: The substrate includes a first dielectric substrate (9) and a second dielectric substrate (8). A low-frequency magnetic ring (3) and a high-frequency magnetic ring (4) are printed on the upper surface of the first dielectric substrate (9), with the high-frequency magnetic ring (4) located inside the low-frequency magnetic ring (3). A first low-frequency dipole arm (1) is printed on the upper surface of the second dielectric substrate (8), and a first high-frequency dipole arm (2) is printed on the lower surface of the second dielectric substrate (8). The first low-frequency dipole arm (1) and the first high-frequency dipole arm (2) are located on the second dielectric substrate. The plate (8) is above the first dielectric substrate (9). The first low-frequency dipole arm (1) and the first high-frequency dipole arm (2) are connected by a metal pillar (7). The upper and lower surfaces of the second dielectric substrate (8) are printed with microstrip transmission lines (6). The microstrip transmission lines (6) are used to connect the port (5), the first low-frequency dipole arm (1) or the second low-frequency dipole arm (1f), the low-frequency magnetic ring (3) and the high-frequency magnetic ring (4). The port (5) is located at the starting end of the microstrip transmission line (6). The first dielectric substrate (9) is a +45° dielectric substrate, the second dielectric substrate (8) is a -45° dielectric substrate, and the low-frequency magnetic ring (3) and the high-frequency magnetic ring (4) are concentric zero-phase-shift magnetic rings. The first dielectric substrate (9) has a first groove (11) and the second dielectric substrate (8) has a second groove (12). The first groove (11) and the second groove (12) are engaged. The first groove (11) and the second groove (12) are used to vertically connect the first dielectric substrate (9) and the second dielectric substrate (8). The lower surface of the second dielectric substrate (8) is printed with a second low-frequency dipole arm (1f) connected to an E-type patch and a rectangular patch. The upper surface of the second dielectric substrate (8) is printed with a second high-frequency dipole arm (2d) with a gradient rectangular patch. The second low-frequency dipole arm (1f) and the second high-frequency dipole arm (2d) are located below the second dielectric substrate (8) relative to the first dielectric substrate (9). The second low-frequency dipole arm (1f) and the second high-frequency dipole arm (2d) are connected by another metal pillar. The first low-frequency dipole arm (1) and the second low-frequency dipole arm (1f) have the same shape. The first high-frequency dipole arm (2) and the second high-frequency dipole arm (2d) have the same shape.

2. The single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The low-frequency magnetic ring (3) is provided with a Y structure (3a) and a first strip structure (3b) that are connected to each other. The Y structure (3a) is Y-shaped and the first strip structure (3b) is arc-shaped. The Y structure (3a) is equivalent to a capacitor element and the first strip structure (3b) is equivalent to an inductor element.

3. The single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The high-frequency magnetic ring (4) is provided with a T-structure (4a) and a second strip structure (4b). The T-structure (4a) is T-shaped, and the second strip structure (4b) is arc-shaped. The T-structure (4a) is equivalent to a capacitor element, and the second strip structure (4b) is equivalent to an inductor element.

4. A single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The rectangular patch includes a first rectangular patch (1a), a second rectangular patch (1b), a third rectangular patch (1c), and a fourth rectangular patch (1d). The first rectangular patch (1a) is a low-impedance microstrip line, and the second rectangular patch (1b) is a high-impedance microstrip line. A first circular hole (1e) is etched on the first rectangular patch (1a). The third rectangular patch (1c) and the fourth rectangular patch (1d) are equal in size and have the same shape. The third rectangular patch (1c) and the fourth rectangular patch (1d) are symmetrical about the second rectangular patch (1b). The width of the first rectangular patch (1a) is greater than the width of the second rectangular patch (1b).

5. A single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: A fifth rectangular patch (2a) and a sixth rectangular patch (2b) are disposed on the second high-frequency dipole arm (2d). A second circular hole (2c) is etched on the fifth rectangular patch (2a). The fifth rectangular patch (2a) is a low-impedance microstrip line, and the sixth rectangular patch (2b) is a high-impedance microstrip line. The shape of the second high-frequency dipole arm (2d) is the same as that of the first high-frequency dipole arm (2). The width of the fifth rectangular patch (2a) is greater than the width of the sixth rectangular patch (2b).

6. A single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The number of microstrip transmission lines (6) is two. The starting position is connected to the port (5), the middle position is connected to the low-frequency magnetic ring (3) and the high-frequency magnetic ring (4), and the ending position is connected to the first low-frequency dipole arm (1) and the second low-frequency dipole arm (1f).

7. A single-port fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The number of metal pillars (7) is two, and the two metal pillars (7) are embedded on the second dielectric substrate (8).

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