Single-port feed dual-frequency omnidirectional circularly polarized antenna

Abstract

The invention discloses a double-frequency omnidirectional circularly polarized antenna with single-port feed. The double-frequency omnidirectional circularly polarized antenna comprises a + 45-degree first dielectric substrate and a-45-degree second dielectric substrate, wherein the + 45-degree first dielectric substrate and the-45-degree second dielectric substrate are vertically intersected. Two concentric zero-phase-shift magnetic rings are printed on the upper surface of the + 45-degree first dielectric substrate, the outer ring is a zero-phase-shift low-frequency magnetic ring, the inner ring is a zero-phase-shift high-frequency magnetic ring, and two arms of a double-frequency dipole are printed on the upper surface and the lower surface of the-45-degree second dielectric substrate respectively. The double-frequency dipole is composed of a first low-frequency dipole and a first high-frequency dipole which are connected through a metal column. A signal enters from a port, and simultaneously excites the first low-frequency dipole arm, the first high-frequency dipole arm, the zero-phase-shift low-frequency magnetic ring and the high-frequency magnetic ring in the same phase through two microstrip feeder lines printed on the upper surface and the lower surface of the-45-degree second dielectric substrate, so that dual-frequency circularly polarized radiation is realized. And the designed low-frequency magnetic ring and the designed 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 invention relates to the technical field of wireless communication and antenna design, and more specifically, to a single-port-fed dual-frequency omnidirectional circularly polarized antenna. Background Art

[0002] Antennas are one of the most important components in wireless communication systems. They undertake the core function of converting electrical signals into electromagnetic waves in space and are widely used in communication, navigation, radar and other fields. With the rapid development of wireless communication technology, the requirements for antenna performance, volume and versatility are constantly increasing. Especially in today's high-speed and complex communication environment, traditional linear polarization antennas cause signal loss due to polarization mismatch and are difficult to meet the needs of stable and efficient communication. For this reason, circularly polarized antennas with high anti-interference ability and excellent polarization matching performance have been widely studied and applied.

[0003] In recent years, the rapid popularization of wireless local area network (WLAN), Bluetooth, and industrial, scientific, and medical (ISM) frequency band communication technologies has put forward the requirement for antennas to work in dual bands. In the two main frequency bands of 2.45GHz and 5.8GHz, although the traditional multi-antenna solution can achieve multi-frequency coverage, it generally requires a feeding network to excite antennas in two different frequency bands, which has a complex structure, high cost, and large power loss. It has gradually become difficult to meet the miniaturization, low power consumption, and high efficiency requirements of modern communication equipment. Therefore, research and development of dual-band antennas with simple structure and excellent performance has become a key direction in 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. They can effectively reduce 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 communications, navigation and positioning, the Internet of Things, and aerospace.

[0005] In this context, there is an urgent need to design a single-port fed dual-band omnidirectional circularly polarized antenna to solve the above problems, and the single-port fed dual-band omnidirectional circularly polarized antenna came into being. Summary of the invention

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

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0009] As a preferred embodiment of the present invention, 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 in the outer ring of the first dielectric substrate, the high-frequency magnetic ring is located in 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 invention, the low-frequency magnetic outer ring is provided with a Y structure and a first strip structure which are connected to each other, the Y structure is in a Y shape, the first strip structure is in an arc shape, 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 invention, a T structure and a second strip structure are provided on the high-frequency magnetic ring, the T structure is T-shaped, the second strip structure is arc-shaped, 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 invention, a first groove is formed on the first dielectric substrate, and a second groove is formed on the second dielectric substrate. The first groove is engaged with the second groove, and the first groove and the second groove are used to vertically connect the first dielectric substrate and the second dielectric substrate.

[0013] As a preferred embodiment of the present invention, a second low-frequency dipole arm connected to a pair of E-type patches and a rectangular patch is also printed on one side of the second dielectric substrate, and the first low-frequency dipole arm and the second low-frequency dipole arm have the same shape;

[0014] The rectangular patch includes 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 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 invention, a second high-frequency dipole arm of a gradient rectangular patch is also 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 the width of the sixth rectangular patch.

[0016] As a preferred embodiment of the present invention, there are two microstrip transmission lines, whose starting positions are connected to the port, whose middle positions are connected to the low-frequency magnetic ring and the high-frequency magnetic ring, and whose end positions are connected to the first low-frequency dipole arm and the second low-frequency dipole arm.

[0017] As a preferred embodiment of the present invention, the number of the metal pillars is two, and the two metal pillars are embedded in the second dielectric substrate.

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

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

[0020] 2. The present invention realizes a single current flow direction by designing two low-frequency magnetic rings and high-frequency magnetic rings with zero phase shift. The designed low-frequency dipole can adjust the coupling relationship. The combination of the two well solves the problem of directional pattern distortion.

[0021] 3. The present invention achieves a 90° phase difference between the two orthogonal component polarizations due to the spatial difference by simultaneously exciting two low-frequency and high-frequency dipoles and two low-frequency and high-frequency magnetic rings in phase, and because of the omnidirectional radiation itself, it has the performance of omnidirectional circular polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a structural schematic diagram of the antenna structure of the present invention;

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

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

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

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

[0027] Figure 6 It is a simulated left-hand and right-hand gain curve diagram of a single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present invention;

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

[0029] Figure 8 It is a simulation result diagram of the H-plane radiation pattern of a single-port-fed dual-frequency omnidirectional circularly polarized antenna at a frequency of 2.45 GHz according to the present invention;

[0030] Fig. 9 It is a simulation result diagram of the E-plane radiation pattern of a single-port-fed dual-frequency omnidirectional circularly polarized antenna at a frequency of 2.45 GHz according to the present invention;

[0031] Fig.10 It is a simulation result diagram of the H-plane radiation pattern of a single-port-fed dual-frequency omnidirectional circularly polarized antenna at a frequency of 5.8 GHz according to the present invention;

[0032] Fig.11 It is a simulation result diagram of the E-plane radiation pattern of a single-port-fed dual-frequency omnidirectional circularly polarized antenna at a frequency of 5.8 GHz according to the present invention;

[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 strip structure; 4, high-frequency magnetic ring; 4a, T structure; 4b, second strip 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 present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] See also Figure 1-4 As shown, a single-port-fed dual-frequency omnidirectional circularly polarized antenna of the present invention includes a first dielectric substrate 9 and a second dielectric substrate 8, wherein 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, wherein the high-frequency magnetic ring 4 is located on the inner side of the low-frequency magnetic ring 3, and a first low-frequency dipole arm 1 and a first high-frequency dipole arm 2 are printed on the upper and lower surfaces of the second dielectric substrate 8, respectively, wherein the first low-frequency dipole arm 1 and the first high-frequency dipole arm 2 are connected by a metal column 7, and the upper and lower surfaces of the second dielectric substrate 8 are printed with a first low-frequency dipole arm 1 and a first high-frequency dipole arm 2. The surfaces are all printed with a microstrip transmission line 6, the microstrip transmission line 6 is used to connect the 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, two microstrip transmission lines 6 can simultaneously excite the first low-frequency dipole arm 1, the first high-frequency dipole arm 2, the low-frequency magnetic ring 3 with zero phase shift, and the high-frequency magnetic ring 4 with zero phase shift in phase, thereby realizing single-port feeding, reducing signal loss, and improving antenna gain. By designing two low-frequency magnetic rings 3 and high-frequency magnetic rings 4 with zero phase shift, a single current flow direction is achieved, and the designed low-frequency dipole can adjust the coupling relationship. The combination of the two well solves the problem of directional pattern distortion. By simultaneously exciting two low-frequency and high-frequency dipoles and two low-frequency and high-frequency magnetic rings in phase, a 90° phase difference is achieved between the two orthogonal component polarizations due to the spatial difference, and the radiation itself is omnidirectional, so it has the performance of omnidirectional circular polarization.

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

[0039] In this embodiment, the first dielectric substrate 9 is a dielectric substrate with an angle of +45°, and the second dielectric substrate 8 is a dielectric substrate with an angle of -45°. Figure 4 As shown, 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 structure 3a designed for the low-frequency magnetic outer ring 3 is equivalent to a capacitor element, and the first strip structure 3b designed is equivalent to an inductor element. The combination of the two can make the current flow in one direction, thereby improving the omnidirectional radiation performance of the antenna.

[0040] In a specific embodiment, Figure 4 As shown, the high-frequency magnetic ring 4 of the present invention is provided with a T structure 4a and a second strip structure 4b, the T structure 4a is in a T shape, the second strip structure 4b is in an arc shape, the T structure 4a is equivalent to a capacitor element, and the second strip structure 4b is equivalent to an inductor element.

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

[0042] In a specific embodiment, Figure 1 As shown, the first dielectric substrate 9 of the present invention is provided with a first groove 11, and the second dielectric substrate 8 is provided with a second groove 12, the first groove 11 is engaged with the second groove 12, and 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; a pair of second low-frequency dipole arms 1f connected to a rectangular patch are also printed on one side of the second dielectric substrate 8, and the first low-frequency dipole arm 1 and the second low-frequency dipole arm 1f have 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, 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, and 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 to a rectangular patch are printed on the -45° second dielectric substrate 8, and a first circular hole 1 is etched on the rectangular patch to facilitate welding of the metal column 7. The dipole structure can reduce coupling and reduce the impact between different working frequency bands. At the same time, it provides low-frequency -45° polarization and omnidirectional radiation, and generates a fixed 90° phase difference with the magnetic ring of the corresponding working frequency band, thereby having good omnidirectional radiation and circular polarization performance.

[0045] In a specific embodiment, Figure 1 As shown, a second high-frequency dipole arm 2d of a gradient rectangular patch is also printed on the other side of the second dielectric substrate 8 of the present invention, a fifth rectangular patch 2a and a sixth rectangular patch 2b are arranged 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, 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 the width of the sixth rectangular patch 2b.

[0046] In this embodiment, a pair of second high-frequency dipole arms 2d of gradient rectangular patches are printed on the second dielectric substrate 8 at -45°, and a second circular hole 2c is etched on the fifth rectangular patch 2a to facilitate welding of metal columns. The dipole structure provides high-frequency -45° polarization and omnidirectional radiation, and generates a fixed 90° phase difference with the magnetic ring of the corresponding working frequency band, thereby having good omnidirectional radiation and circular polarization performance.

[0047] In a specific embodiment, Figure 3 As shown, the number of the microstrip transmission lines 6 of the present invention is two, the starting position of which 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 end position is connected to the first low-frequency dipole arm 1 and the second low-frequency dipole arm 1f.

[0048] In this embodiment, when a signal enters from the port 5, the two microstrip transmission lines 6 can be used to transmit the signal and excite the antenna at the same time.

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

[0050] In this embodiment, the second dielectric substrate 8 is embedded with two metal pillars 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 5This is a simulated S11 parameter curve of a single-port-fed dual-band omnidirectional circularly polarized antenna in this example. The frequency bands with S parameters lower than -10dB include two frequency bands: 2.31GHz to 2.55GHz and 5.55GHz to 5.86GHz.

[0052] Figure 6 This is a simulated left-hand and right-hand gain curve of a single-port-fed dual-band omnidirectional circularly polarized antenna in this example. It can be seen that the rotation direction of the low-frequency band is left-handed, and the rotation direction of the high-frequency band is left-handed.

[0053] Figure 7 This is a simulated axial ratio parameter curve of a single-port-fed dual-band omnidirectional circularly polarized antenna in this example. It can be seen that the axial ratios in both the 2.45 GHz and 5.8 GHz frequency bands are lower than 3 dB, and their rotation directions are both left-hand circular polarization.

[0054] Figure 8-9 These are the simulated low-frequency E-plane and H-plane radiation patterns of a single-port-fed dual-band omnidirectional circularly polarized antenna in this example.

[0055] Figure 9-11 The simulated high-frequency E-plane and H-plane radiation patterns of a single-port-fed dual-band omnidirectional circularly polarized antenna in this example.

[0056] In summary, the dual-band omnidirectional circularly polarized antenna with single-port feeding adopts a single feeding structure and achieves efficient coverage of the 2.45GHz and 5.8GHz frequency bands through optimized design. It not only eliminates the design of the feeding network, but also significantly reduces power loss and manufacturing costs, and improves the gain and overall efficiency of the antenna. While achieving dual-band omnidirectional circularly polarized performance, it effectively solves the problem of high-frequency radiation pattern distortion caused by coupling effects in multi-band antennas. The antenna has excellent impedance matching and circular polarization performance in a miniaturized structure, significantly reduces the size of the antenna, and overcomes the problems of large size, distorted radiation pattern, low gain, and complex design of traditional dual-band antennas. It provides an innovative solution to the multi-band, high-performance, and compact requirements of modern wireless communication equipment.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dual-frequency omnidirectional circularly polarized antenna with single-port feeding, characterized in that: The invention comprises 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); the high-frequency magnetic ring (4) is located inside the low-frequency magnetic ring (3); a first low-frequency dipole arm (1) and a first high-frequency dipole arm (2) are printed on the upper and lower surfaces of the second dielectric substrate (8), respectively; the first low-frequency dipole arm (1) and the first high-frequency dipole arm (2) are connected via a metal column (7); a microstrip transmission line (6) is printed on the upper and lower surfaces of the second dielectric substrate (8); 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).

2. A single-port-fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The first dielectric substrate (9) is a dielectric substrate with an angle of +45°, the second dielectric substrate (8) is a dielectric substrate with an angle of -45°, the low-frequency magnetic ring (3) is located on the outer ring of the first dielectric substrate (9), the high-frequency magnetic ring (4) is located on 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.

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

4. 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 in a T shape, and the second strip structure (4b) is in an arc shape; the T structure (4a) is equivalent to a capacitor element, and the second strip structure (4b) is equivalent to an inductor element.

5. The single-port-fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: The first dielectric substrate (9) is provided with a first groove (11), the second dielectric substrate (8) is provided with a second groove (12), the first groove (11) and the second groove (12) are snap-fitted, and 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).

6. The single-port-fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: A second low-frequency dipole arm (1f) connected to a pair of E-shaped patches and a rectangular patch is also 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) have the same shape; The rectangular patch comprises 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, 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 with respect to the second rectangular patch (1b), and the width of the first rectangular patch (1a) is greater than the width of the second rectangular patch (1b).

7. The single-port-fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: A second high-frequency dipole arm (2d) of a gradient rectangular patch is also printed on the other side of the second dielectric substrate (8); a fifth rectangular patch (2a) and a sixth rectangular patch (2b) are arranged 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; 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 the width of the sixth rectangular patch (2b).

8. The single-port-fed dual-frequency omnidirectional circularly polarized antenna according to claim 1, characterized in that: There are two microstrip transmission lines (6), the starting position of which 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 end position is connected to the first low-frequency dipole arm (1) and the second low-frequency dipole arm (1f).

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

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