An H-type decoupling structure between circularly polarized patch antennas

Abstract

The invention discloses an H-type decoupling structure between circularly polarized patch antennas, comprising a metal grounding plate, a rectangular dielectric substrate, a first circularly polarized patch antenna, a second circularly polarized patch antenna and an "H"-shaped microstrip resonator which are arranged in sequence from bottom to top; the "H"-shaped microstrip resonator is symmetrically placed in the middle of the coupling area of ​​the first circularly polarized patch antenna and the second circularly polarized patch antenna; the invention introduces a new electromagnetic signal coupling channel between the first circularly polarized patch antenna and the second circularly polarized patch antenna, so that the coupling signal of the first circularly polarized patch antenna passing through the channel and the coupling signal of the second circularly polarized patch antenna passing through the channel are equal in amplitude and opposite in direction, and the coupling signals are mutually offset, thereby realizing coupling suppression between adjacent circularly polarized patch antenna units. The invention has the advantages of simple structure, low profile, easy integration and low back radiation, and is suitable for various wireless systems such as mobile communication and satellite communication.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to an H-type decoupling structure between circularly polarized patch antennas. Background Art

[0002] Circularly polarized antennas have significant advantages in long-distance transmission and anti-interference. Circularly polarized waves have little attenuation when propagating in wind and rain, can penetrate the ionosphere, and are not affected by the Dalady effect generated by the earth's magnetic field. Therefore, circularly polarized antennas are widely used in the fields of wireless communications and radar monitoring, especially in base station communications, showing their unique advantages and importance. For example, the application of circularly polarized antennas in LTE MIMO systems can ensure the balance of received signal power and ensure that the signal-to-noise ratio is not reduced under the premise of the same system bandwidth and number of channels, thereby improving system capacity.

[0003] On the other hand, Multiple-Input Multiple-Output (MIMO) technology, as a key technology supporting the rapid development of 5G technology, has received widespread attention from the public in recent years. However, with the development of communication equipment towards miniaturization and integration, the center spacing of units in the antenna array continues to decrease, and the mutual coupling effect between antenna units becomes more and more obvious, which challenges the independent radiation characteristics of the antenna units and ultimately seriously affects the overall performance of the antenna array. Although, in recent years, researchers have studied various decoupling methods between antenna units in linearly polarized MIMO arrays and achieved remarkable results. However, limited by the special radiation characteristics of circularly polarized antennas, at present, domestic and foreign academic and industrial circles lack effective measures on how to reduce the mutual coupling between circularly polarized antenna array units. Therefore, a miniaturized, low-profile, high-performance decoupling structure suitable for circularly polarized patch antennas has very important application value.

[0004] The existing decoupling methods between circularly polarized patch antenna units mainly include diversity technology, loading defective ground structure, frequency selective surface, loading parasitic elements and other technical methods. In reference 1 (MY Jamal, M. Li and KL Yeung, "Isolation Enhancement of Closely Packed Dual Circularly Polarized MIMOAntenna Using Hybrid Technique," in IEEE Access, vol. 8, pp. 11241-11247, 2020), a pair of microstrip patch antennas symmetrically placed relative to the y-axis are proposed. The matching and isolation between the two patch antennas are achieved by loading three parallel stubs and a mirror F-type defective ground structure (DGS) between the antenna units. The bias feeding method is used to make the two antenna units present different polarization states. By utilizing the characteristics of polarization orthogonality, the mutual coupling level can be suppressed to below -20dB within the working frequency band. However, the technical feature of the defective ground structure is to dig grooves on the antenna floor, which destroys the integrity of the floor and easily causes the backward leakage of the antenna radiation, affecting the antenna radiation performance. In reference 2 (N.-W. Liu, L. Zhu, Z. -X. Liu, M. Li, G. Fu and Y. Liu, "A Novel Low-Profile Circularly Polarized Diversity Patch Antenna With Extremely Small Spacing, Reduced Size, and Low Mutual Coupling," in IEEE Transactions on Antennas and Propagation, vol. 70, no. 1, pp. 135-144, Jan. 2022), based on the method of characteristic mode analysis, a pair of microstrip patch antennas with a size of one-quarter of the patch and symmetrically placed relative to the y-axis were proposed. The antenna is equipped with a short-circuit post to excite a specific radiation mode. By etching linear slots along the diagonal direction of the patch, the antenna unit presents a circularly polarized working state. The orthogonal characteristics of polarization are utilized to achieve high isolation between antenna units.In reference 3 (M. Akbari, H. AboGhalyon, M. Farahani, A. -R. Sebak and TA Denidni, "Spatially Decoupling of CP Antennas Based on FSS for 30-GHz MIMO Systems," in IEEE Access, vol. 5, pp. 6527-6537, 2017), a MIMO antenna decoupling structure based on frequency selective surface is proposed. The antenna consists of a 2x2 aperture coupled microstrip patch antenna and two layers of FSS. The decoupling between MIMO antennas is achieved by regularly loading planar cross-dipole metal strips on the upper layer of FSS. This reference introduces an effective way to alleviate near-field coupling, but the structure is complex to manufacture and requires a large design space. At the same time, the design requires the design optimization of the FSS unit cell with a multi-layer substrate, which is difficult to mass produce.

[0005] To sum up, the problems existing in the prior art are: the decoupling structure of the circularly polarized patch MIMO antenna is difficult to simultaneously meet the requirements of miniaturization and low profile while achieving good performance. At present, there is little research on the decoupling structure of the circularly polarized patch MIMO antenna, which is not conducive to the promotion and use of the circularly polarized patch MIMO antenna in practical applications. Summary of the invention

[0006] The present invention aims to provide a miniaturized, low-profile decoupling structure for reducing mutual coupling between circularly polarized patch antennas, so as to solve the problems in the above background.

[0007] The technical solution to achieve the purpose of the present invention is: an H-type decoupling structure between circularly polarized patch antennas, the decoupling structure includes a metal grounding plate and a rectangular dielectric substrate arranged in sequence from bottom to top, the upper surface of the rectangular dielectric substrate is provided with a first circularly polarized patch antenna, a second circularly polarized patch antenna and an "H"-shaped microstrip resonator; the first circularly polarized patch antenna and the second circularly polarized patch antenna are respectively provided with a first input port and a second input port; the "H"-shaped microstrip resonator is composed of a branch one and a branch two and a branch three perpendicular to the branch one, and the branch one and the branch two are parallel, and the four terminals of the two branches one and two are respectively provided with a metallized grounding through hole one, a metallized grounding through hole two, a metallized grounding through hole three, and a metallized grounding through hole four, and an isosceles triangle cut angle is set at the connecting part between the middle section of the branch one and the branch two and the branch three, and the "H"-shaped microstrip resonator is symmetrically placed in the middle of the coupling area of ​​the first circularly polarized patch antenna and the second circularly polarized patch antenna.

[0008] Preferably, the first circular polarization patch antenna and the second circular polarization patch antenna have the same structure and are symmetrically arranged about the center of the rectangular dielectric substrate.

[0009] Preferably, the main parts of the first circular polarization patch antenna and the second circular polarization patch antenna are both square structures, and two of the four corners of the square structure located on the diagonal are cut corners, and after cutting the corners, the square structure produces four long sides and two oblique sides; the four long sides of the square structure are parallel to the four sides of the rectangular dielectric substrate.

[0010] Preferably, the first input port and the second input port are respectively located on the central axis of the first circular polarization patch antenna and the second circular polarization patch antenna along the X-axis.

[0011] Preferably, the distance from the first input port to the center of the first circular polarization patch antenna is equal to the distance from the second input port to the center of the second circular polarization patch antenna.

[0012] Preferably, the first input port and the second input port are both fed by an SMA signal probe to input signals to the first circular polarization patch antenna and the second circular polarization patch antenna respectively.

[0013] Preferably, the “H”-shaped microstrip resonator is a centrosymmetric structure.

[0014] Preferably, the two ends of branch three are respectively connected to the middle sections of branch one and branch two, and the two isosceles triangles at the connection are symmetrically etched with cut corners, and are located close to one side of the first circular polarization patch antenna and the second circular polarization patch antenna, respectively.

[0015] Preferably, the relative dielectric constant of the rectangular dielectric substrate is 2.2 and the thickness is 0.635 mm.

[0016] Furthermore, the relative dielectric constant of the rectangular dielectric substrate is 2.2 and the thickness is 0.635 mm.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] 1. The decoupling structure between the circularly polarized patch antennas provided by the present invention is a single-layer design, which well retains the advantage of the low profile of the microstrip patch antenna and has the advantages of easy processing and integration;

[0019] 2. The decoupling structure between the circularly polarized patch antennas provided by the present invention is placed between the antenna units, making the entire design structure compact and conducive to miniaturization;

[0020] 3. By controlling the size of the circularly polarized patch antenna and the "H"-shaped microstrip resonator, the circularly polarized patch antenna can be operated and decoupled in any frequency band, and the structure is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the three-dimensional structure of a circularly polarized patch antenna with a decoupling structure between antenna units;

[0022] Figure 2 A schematic diagram of the cross-sectional structure of a circularly polarized patch antenna with a decoupling structure between antenna units;

[0023] Figure 3 This is a comparison diagram of S parameters between circularly polarized patch antennas with and without decoupling structures, where (a) corresponds to the S parameters of circularly polarized patch antennas without decoupling structures, and (b) corresponds to the S parameters of circularly polarized patch antennas with decoupling structures;

[0024] Figure 4 This is a simulation diagram of the antenna axial ratio when a decoupling structure is loaded between circularly polarized patch antennas;

[0025] Figure 5 The radiation pattern of the XOZ plane when a decoupling structure is loaded between circularly polarized patch antennas. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0027] Reference Figure 1 and attached Figure 2 As shown, an H-type decoupling structure between circularly polarized patch antennas is provided in the embodiment, and the decoupling structure includes a metal ground plate 1 and a rectangular dielectric substrate 2 arranged in sequence from bottom to top; a first circularly polarized patch antenna 3, a second circularly polarized patch antenna 4 and an "H"-shaped microstrip resonator 7 are arranged on the upper surface of the rectangular dielectric substrate 2, and the first circularly polarized patch antenna 3 and the second circularly polarized patch antenna 4 are symmetrically arranged about the center of the rectangular dielectric substrate 2; the first circularly polarized patch antenna 3 and the second circularly polarized patch antenna 4 are both square patches, and two corners located on the diagonal of the four corners of the square structure are cut corners; the first circularly polarized patch antenna 3 and the second circularly polarized patch antenna 4 are respectively provided with a first input port 5 and a second input port 6, and the first input port 5 and the second input port 6 are respectively located on the central axis of the first circularly polarized patch antenna 3 and the second circularly polarized patch antenna 4 along the X-axis; when in use, the first input port 5 is fed by a power supply, and is fed through an SMA signal probe, thereby realizing feeding of the entire antenna structure.

[0028] Reference Figure 1 and attached Figure 2 As shown, in the embodiment, the "H"-shaped microstrip resonator 7 is composed of two branches 1 7e and 7f parallel to the longitudinal direction (X axis) and one branch 3 7g parallel to the transverse direction (Y axis). The four terminals of the two longitudinal branches 1 7e and 7f are respectively provided with a metallized grounding through hole 1 7a, a metallized grounding through hole 2 7b, a metallized grounding through hole 3 7c, and a metallized grounding through hole 4 7d. The connecting part between the middle section of the two longitudinal branches 1 7e and 7f and the transverse branch 3 7g introduces an isosceles triangle cut-angle form, and the "H"-shaped microstrip resonator 7 is symmetrically placed in the middle of the coupling area of ​​the first circular polarization patch antenna 3 and the second circular polarization patch antenna 4.

[0029] The "H"-shaped microstrip resonator 7 introduces a new electromagnetic signal coupling channel between the first circularly polarized patch antenna 3 and the second circularly polarized patch antenna 4. The two coupling signals of the first circularly polarized patch antenna 3 enter the "H"-shaped microstrip resonator 7 through the two ends of the branch one 7e parallel to the longitudinal direction (X-axis), and the two coupling signals of the second circularly polarized patch antenna 4 enter the "H"-shaped microstrip resonator 7 through the two ends of the branch two 7f parallel to the longitudinal direction (X-axis). The four coupling signals are equal in amplitude and opposite in direction in pairs, and cancel each other out at the branch three 7g parallel to the transverse direction (Y-axis), thereby realizing coupling suppression between adjacent circularly polarized patch antenna units.

[0030] Figure 3 (a) is the S parameter when there is no decoupling structure between circularly polarized patch antennas. Figure 3 (b) shows the S parameters when a decoupling structure is loaded between circularly polarized patch antennas; for comparison Figure 3 It can be found in (a) and (b) that when the decoupling structure is loaded, the mutual coupling level between the antennas is significantly reduced, and the isolation impedance bandwidth is widened to a certain extent; the -10dB impedance matching bandwidth of this embodiment is from 3.48GHz to 3.56GHz, and the port coupling between the two antenna units is maintained below -20dB within 3.49GHz to 3.52GHz.

[0031] Figure 4 This is a simulation diagram of the antenna axial ratio when a decoupling structure is loaded between circularly polarized patch antennas. It can be seen that the present invention can reduce the mutual coupling level between patch antennas while maintaining the original circular polarization characteristics of the radiating antenna. The 3dB axial ratio frequency band ranges from 3.49GHz to 3.51GHz, which is consistent with the -20dB isolation impedance bandwidth range.

[0032] Figure 5This is the radiation pattern when the decoupling structure is loaded between the circularly polarized patch antennas. Observing the radiation pattern of the XOZ plane, it can be seen that after the decoupling structure is loaded, the maximum directional gain of the antenna is 5.3dB. Comparing the radiation patterns of the circularly polarized patch antennas at different frequencies, it can be seen that within the 3dB axial ratio frequency band, the antenna pattern has almost no change, proving that the present invention has no effect on the radiation performance of the antenna, and the antenna radiation performance remains stable.

[0033] In summary, the present invention has a good decoupling effect between circularly polarized patch antennas, a stable radiation pattern, a small size, a simple structure, and can be widely used in various wireless systems such as mobile communications and satellite communications.

[0034] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technology can understand and think of any changes or substitutions within the technical scope disclosed by the present invention, which should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An H-type decoupling structure between circularly polarized patch antennas, characterized in that: The decoupling structure comprises a metal ground plate (1) and a rectangular dielectric substrate (2) which are arranged in sequence from bottom to top; a first circular polarization patch antenna (3), a second circular polarization patch antenna (4) and an "H"-shaped microstrip resonator (7) are arranged on the upper surface of the rectangular dielectric substrate (2); a first input port (5) and a second input port (6) are arranged on the first circular polarization patch antenna (3) and the second circular polarization patch antenna (4), respectively; the "H"-shaped microstrip resonator (7) is composed of a branch node 1 (7e) and a branch node 2 (7f) and a branch node 3 (7g) which is perpendicular to the branch node 1 (7e), and the branch node 1 (7e) and the branch node 2 (7f) are parallel to each other, and the four Each terminal is provided with a metallized grounding through hole 1 (7a), a metallized grounding through hole 2 (7b), a metallized grounding through hole 3 (7c), and a metallized grounding through hole 4 (7d), and an isosceles triangle cut corner is provided at the connection part between the middle section of the branch 1 (7e), the branch 2 (7f) and the branch 3 (7g), and the two ends of the branch 3 (7g) are respectively connected to the middle section of the branch 1 (7e) and the branch 2 (7f), and the two isosceles triangle cut corners at the connection are symmetrically etched and are located on one side close to the first circular polarization patch antenna (3) and the second circular polarization patch antenna (4), respectively. The "H"-shaped microstrip resonator (7) is symmetrically placed in the middle of the coupling area of ​​the first circular polarization patch antenna (3) and the second circular polarization patch antenna (4).

2. The H-type decoupling structure between circularly polarized patch antennas according to claim 1, characterized in that: The first circularly polarized patch antenna (3) and the second circularly polarized patch antenna (4) have the same structure and are symmetrically arranged about the center of the rectangular dielectric substrate (2).

3. The H-type decoupling structure between circularly polarized patch antennas according to claim 2, characterized in that: The main parts of the first circular polarization patch antenna (3) and the second circular polarization patch antenna (4) are both square structures. Two of the four corners of the square structure located on the diagonal line are cut off. After the corners are cut off, the square structure generates four long sides and two oblique sides. The four long sides of the square structure are parallel to the four sides of the rectangular dielectric substrate (2).

4. The H-type decoupling structure between circularly polarized patch antennas according to claim 3, characterized in that: The first input port (5) and the second input port (6) are respectively located on the longitudinal center axis of the first circular polarization patch antenna (3) and the second circular polarization patch antenna (4).

5. The H-type decoupling structure between circularly polarized patch antennas according to claim 4, characterized in that: The distance from the first input port (5) to the center of the first circularly polarized patch antenna (3) is equal to the distance from the second input port (6) to the center of the second circularly polarized patch antenna (4).

6. The H-type decoupling structure between circularly polarized patch antennas according to claim 5, characterized in that: The first input port (5) and the second input port (6) are both fed by an SMA signal probe to input signals to the first circularly polarized patch antenna (3) and the second circularly polarized patch antenna (4) respectively.

7. The H-type decoupling structure between circularly polarized patch antennas according to claim 1, characterized in that: The "H"-shaped microstrip resonator (7) is a centrally symmetrical structure.

8. The H-type decoupling structure between circularly polarized patch antennas according to claim 1, characterized in that: The rectangular dielectric substrate (2) has a relative dielectric constant of 2.2 and a thickness of 0.635 mm.

Images