A planar integrated circularly polarized magneto-electric dipole antenna with tooth-like openings

Abstract

The application discloses a tooth-shaped opening planar integrated circularly polarized magneto-electric dipole antenna based on a printed circuit board process and belongs to the microwave antenna field.The circularly polarized magneto-electric dipole antenna comprises a first dielectric substrate 1, a metal ground plate 2 and a lower second dielectric substrate 3 which are of the same size and closely adhere to each other, and metalized through holes, a tooth-shaped opening metal patch 5 is arranged at the center of the upper surface of the first dielectric substrate, the metal patch is subjected to corner cutting and tooth-shaped opening 7 treatment, two rows of metalized through holes are arranged in the first dielectric substrate and connect the metal patch with the metal ground plate, the upper surface of the second dielectric substrate is a metal bottom plate with a gap 8, and the lower surface of the dielectric substrate is a rectangular microstrip line 9 as a feeding structure, so that the structure is simple, the electric size is small, and the planar integrated structure is easier to process and array.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and in particular relates to a planar integrated circularly polarized magnetoelectric dipole antenna with a tooth-shaped opening. Background Art

[0002] The continuous development of modern wireless communication systems requires more stable communications in complex environments and conditions. Circularly polarized antennas offer significant advantages, including strong resistance to polarization interference, multipath fading, and strong penetration, making them widely used in radar, satellite communications, and global positioning systems. The magnetoelectric dipole antenna, proposed by Professor Kwai-Man Luk in 2006 based on the principle of complementarity, offers inherent advantages such as broadband, a stable and symmetrical radiation pattern, low backlobe radiation, and low cross-polarization, making it an optimal antenna choice for many wireless communication systems.

[0003] Compared to other antennas, magnetoelectric dipole antennas offer significant advantages in high gain, broadband, and a stable radiation pattern. This is why circularly polarized magnetoelectric dipole antennas have emerged. They achieve circular polarization by creating two orthogonal, equal-amplitude radiated electric fields with a 90° phase difference between the magnetic and electric dipole elements of the magnetoelectric dipole.

[0004] In recent years, scholars both domestically and internationally have studied the applications of circularly polarized magneto-electric dipole antennas. In 2019, J. Sun et al. published an article titled "Wideband Linearly-Polarized and Circularly-Polarized Aperture-Coupled Magneto-Electric Dipole Antennas Fed by Microstrip Line With Electromagnetic Bandgap Surface" in IEEE Access (vol. 7, pp. 43084-91, March 2019). By combining two pairs of all-metal linearly polarized magneto-electric dipoles and adding branches, they achieved circularly polarized radiation. The antenna's bandwidth is 58% (3.44-6.27 GHz), and the bandwidth with an axial ratio less than 3dB is 22.5% (3.75-4.7 GHz). Furthermore, by adding an EBG structure to the antenna's base layer, the authors were able to effectively suppress backward radiation.

[0005] In 2020, YF Wang et al. published an article titled "Wideband Circularly Polarized Magneto-Electric Dipole 1×2 Antenna Array for Millimeter-Wave Applications" in IEEE Access (vol. 8, pp. 27516-27523, February 2020). The authors achieved circular polarization by partially cutting the electric dipole of the magneto-electric dipole and adding branches. The circular polarization bandwidth was only 9.7% (27.4-30.20). To expand the axial ratio bandwidth, the authors formed a 1×2 antenna array and designed a 1-to-2 power splitter with a 90° phase difference based on a substrate integrated waveguide (SIW) as the feeding network. The measurement results showed that the axial ratio bandwidth was 24.7% and the maximum in-band gain was 10dBic, which is 2.4 times higher than the 3dB AR bandwidth of a single antenna unit. However, the antenna size at this time is 3.5λ0×3.5λ0×0.14λ0 (λ0 is the wavelength corresponding to the center frequency of the antenna array), so the number of antennas that can be placed in a certain space is limited.

[0006] In 2021, LQ Wang et al. published a paper entitled “Design of a Ka-Band Low-Profile Wideband Circularly Polarized Magneto-Electric Dipole Antenna With Parasitic Patches and Its Array” at the IEEE Asia-Pacific Microwave Conference (APMC) (November 28-December 01, 2021, Brisbane, Australia). The antenna element replaces the rectangular electric dipole of the linearly polarized magneto-electric dipole antenna with two inverted L metal strips to produce circularly polarized radiation. At the same time, four parasitic patches are added around the electric dipole to optimize the distribution of the far-field orthogonal field to achieve a low profile and extend the circular polarization bandwidth. Ultimately, the antenna profile is greatly reduced from the traditional 0.25λ0 to 0.1λ0, and the overlapping bandwidth of the impedance bandwidth and the circular polarization bandwidth can reach 19.8%. However, the addition of the parasitic structure not only complicates the structure of the antenna, but also increases its size to 1λ0×1λ0×0.1λ0. For application scenarios with limited space, the antenna is greatly restricted.

[0007] Therefore, this antenna has received widespread attention from scholars at home and abroad since it was proposed. Based on this antenna, researchers have proposed antenna design schemes with different frequency bands and various styles, which gives it great application potential in many fields and has certain research value. Summary of the Invention

[0008] The purpose of this invention is to provide a planar integrated circularly polarized magnetoelectric dipole antenna with a tooth-shaped opening, utilizing the fundamental principles of magnetoelectric dipoles. The antenna achieves circular polarization primarily through a novel tooth-shaped opening structure. Furthermore, the antenna is compact overall, and its planar integrated structure facilitates array applications.

[0009] The technical problem proposed by the present invention is solved as follows:

[0010] A planar integrated circularly polarized magnetoelectric dipole antenna with a tooth-shaped opening comprises a first dielectric plate, a metal floor, and a second dielectric substrate of the same size and tightly fitted from top to bottom;

[0011] A pair of rotationally symmetrical, tooth-shaped metal patches are positioned at the center of the top surface of the first dielectric substrate, with a certain spacing between them. These patches are also treated with added nodes and chamfered corners. Ten metalized through-holes (PTHs) are arranged in two rows of rotationally symmetrical rows, with the center of symmetry being the exact center of the dielectric substrate. These PTHs extend through the PTHs and connect the metal floor. To ensure a good connection between the PTHs and the metal floor, the spacing between the two rows of PTHs is slightly greater than the spacing between the two metal patches. A rectangular slot is etched in the exact center of the metal floor, with the two metal patches positioned directly above it. The edges of the two metal patches overlap the slot, making the slot wider than the spacing between the two metal patches. This enhances coupling between electromagnetic wave energy passing through the slot and the two metal patches.

[0012] By performing serration opening and angle cutting on a pair of serrated metal patches on the upper surface of the first dielectric plate, the phase and direction of current flow thereon can be effectively changed, thereby optimizing the circular polarization radiation performance of the antenna.

[0013] A gap is etched in the center of the metal floor, parallel to the long side of the tooth-shaped open metal patch, and its center point coincides with the rotation center of the two tooth-shaped open metal patches. In order to enhance the coupling between the electromagnetic wave energy passing through the gap and the two metal patches, the width of the gap is greater than the spacing between the two tooth-shaped open metal patches.

[0014] A microstrip feeding structure is provided on the lower surface of the second dielectric substrate. The microstrip feeding structure is a microstrip line with an impedance of 50 ohms. It is located in the center of the dielectric substrate and extends from the edge of the dielectric substrate to just below the gap in the metal floor, and extends slightly beyond the position of the gap.

[0015] A rectangular slot is etched in the metal floor, through which the energy of the microstrip line can be coupled to the metallized through-hole in the first dielectric plate and the tooth-shaped opening metal patch on the upper layer, thereby exciting a circularly polarized radiation wave.

[0016] The antenna ports all adopt microstrip feeding mode, and the input impedance of the ports is 50 ohms.

[0017] The beneficial effects of the present invention are:

[0018] (1) Based on the fundamental principle of magnetoelectric dipoles, the present invention utilizes two rows of metal through-holes in the first dielectric plate 1 to simulate the vertical metal walls of a full-metal magnetoelectric dipole, enabling an equivalent magnetic flux to be excited within the two rows of metal through-holes. By modifying the shape of the two tooth-shaped open metal patches 5 and optimizing the current distribution thereon, the current and the equivalent magnetic flux can interact to generate two equal-amplitude orthogonal electric fields with a 90° phase difference, thereby achieving circularly polarized radiation.

[0019] (2) The pair of serrated metal patches on the upper surface of the first dielectric plate 1 of the present invention are treated with serrated openings to effectively change the phase of the current flowing thereon, thereby optimizing the circularly polarized radiation performance of the antenna. By adding branches to the pair of serrated metal patches on the upper surface of the first dielectric plate 1, the first resonant frequency of the antenna can be adjusted, thereby optimizing the antenna matching. Furthermore, by adjusting the length of the branches of the serrated metal patches 5, the direction of current flow thereon can be adjusted, so that the overall direction of current flow is parallel to the long side of the serrated metal patches.

[0020] (3) The present invention changes the magnetoelectric dipole 'I-type feeding structure into microstrip line coupling feeding, which facilitates the processing, integration and array formation of the antenna.

[0021] (4) The circularly polarized magnetoelectric dipole with tooth-shaped openings described in the present invention has a wide bandwidth, a small size, and a planar integrated structure, which is convenient for forming a circularly polarized antenna array. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of the toothed open circularly polarized magnetoelectric dipole antenna according to an embodiment of the present invention;

[0023] Figure 2 for Figure 1 Side view of the middle antenna;

[0024] Figure 3 for Figure 2 A top view of the upper surface metal layer and metallized through-holes of the first dielectric substrate in the upper middle layer;

[0025] Figure 4 for Figure 2 Top view of the middle metal layer;

[0026] Figure 5 for Figure 2 A top view of the metal layer on the lower surface of the second dielectric substrate in the middle and lower layers;

[0027] Figure 6 Schematic diagram of the S parameters and gain of the antenna described in the embodiment;

[0028] Figure 7 Schematic diagram of the axial ratio of the antenna according to the embodiment;

[0029] Figure 8 This is a diagram showing the metal surface current and gap electric field distribution when the antenna described in the embodiment operates at 6.74 GHz;

[0030] Figure 9 This is the far-field radiation pattern of the antenna described in the embodiment when operating at 6.74 GHz. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples.

[0032] This embodiment provides a planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings. The overall structural diagram is shown in FIG. Figure 1 As shown, the side view is Figure 2 As shown, it includes a first dielectric substrate 1, a metal floor 2, and a second dielectric substrate 3 of identical size and tightly fitted from top to bottom. The first dielectric substrate 1 is provided with two rows of metallized through-holes 4, totaling 10. The two rows of metallized through-holes are rotationally symmetrical, with the center of symmetry being the exact center of the dielectric substrate. The metallized through-holes penetrate the tooth-shaped opening metal patch 5 and the metal floor 2, connecting the two. To ensure that the metal through-holes can effectively connect the tooth-shaped opening metal patch 5 and the metal floor 2, the spacing between the two rows of metal through-holes is slightly larger than the spacing 6 between the metal patches. A top view of the metal layer and metal through-holes on the upper surface of the first dielectric substrate 1 is shown in FIG. Figure 3 As shown, a pair of rotationally symmetrical metal patches 5 with tooth-shaped openings are provided at the center of the upper surface as the radiation structure of the antenna; there is a certain distance 6 between the two metal patches, and the metal patches are subjected to tooth-shaped openings, branch additions and angle cutting 7. The top view of the metal floor 2 is shown as follows: Figure 4 As shown, a rectangular slit 8 is etched in the center, parallel to the long side 10 of the tooth-shaped open metal patch, and its center coincides with the rotation center of the two tooth-shaped open metal patches. The long sides 10 of the two metal patches cover the slit 8, making the width of the slit 8 larger than the spacing 6 between the two metal patches, so as to enhance the coupling between the electromagnetic wave energy passing through the slit and the two metal patches. The top view of the metal layer on the lower surface of the second dielectric substrate 3 is shown in FIG. Figure 5As shown, a microstrip feeding structure is provided on the lower surface. The microstrip feeding structure is a microstrip line 9 with an impedance of 50 ohms, which is located in the center of the dielectric substrate and extends from the edge of the dielectric substrate to just below the gap 8 of the metal floor 2, and further extends beyond the position of the gap.

[0033] The first dielectric substrate 1 is made of Rogers RO3203, with a relative dielectric constant of 3.03, a loss tangent of 0.0016, and a thickness of 5.5 mm. The second dielectric substrate 2 is made of Rogers RT5880, with a relative dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.5 mm. The dielectric substrates have the same dimensions of 36 mm × 36 mm. The rectangular metal patch 5 measures 12.5 mm × 5.55 mm, with four tooth-shaped openings, a depth of 1.2 mm, and a width of 1 mm. The spacing between the two metal patches is 2 mm. There are 10 metal through-holes in the first dielectric substrate 1, with a radius of 0.5 mm and a spacing of 0.425 mm between adjacent through-holes. The rectangular slots in the metal ground plane 2 are 10 mm long and 2.9 mm wide. The open-circuit termination in the microstrip feed structure is a microstrip line with a width of 2.4 mm and a length of 22 mm.

[0034] The dimensions of the antenna in this embodiment are 0.78λ0×0.78λ0×0.13λ0 (λ0 is the wavelength corresponding to the center frequency of the antenna operating frequency band). The S parameter simulation results and gain diagram are shown in FIG. Figure 6 As shown, there are two resonant frequencies f l and f h The operating frequency band is 5.65-7.38GHz (relative bandwidth 26.6%), and the average gain of the antenna in the band is 7.12dBi. The frequency range where the axial ratio is less than 3dB is 6.53-7.22GHz (10%). The axial ratio diagram of the antenna is as follows: Figure 7 shown.

[0035] The circularly polarized magnetoelectric dipole designed in this embodiment generates circularly polarized radiation through the combined action of magnetic and electric currents. In this structure, electromagnetic wave energy couples through the gaps in the metal floor to the metal patch 5 above, generating an electric current that radiates electromagnetic waves. Because the two closely spaced rows of metal vias can be considered two metal walls, a portion of the electromagnetic energy interacts with them, forming an equivalent magnetic current. Figure 8The current distribution on the patch surface and the electric field distribution at the gap of the designed antenna when operating at 6.74 GHz are shown. It can be seen that at t = T / 4 and t = 3T / 4, the two rows of metallized vias connected to the metal patch are excited, and the electric field intensity at the gap is maximum, equivalent to generating magnetic currents in the +y and -y directions, respectively. At t = 0 and t = T / 2, the electric dipole is excited, and the current on the patch surface mainly flows in the +y and -y directions. It can be seen that within a cycle, the current and the equivalent magnetic current alternate in the same direction, with a phase difference of 90°, thus generating circularly polarized radiation waves.

[0036] The radiation pattern of the antenna at 6.74GHz is as follows Figure 9 The antenna unit maintains good broadside characteristics throughout the entire frequency band, with a cross-polarization discrimination (XPD) greater than 20dB in the z-axis direction, demonstrating excellent polarization characteristics.

[0037] The magnetoelectric dipole antenna described in this embodiment adopts a novel tooth-shaped opening structure to achieve circular polarization, and changes the existing magnetoelectric dipole antenna'I-type feeding structure to microstrip line coupling feeding. This feeding method facilitates antenna processing, integration and array formation.

[0038] Finally, the circularly polarized magnetoelectric dipole has a wide bandwidth, a small size, and a planar integrated structure, which is convenient for forming a circularly polarized antenna array.

Claims

1. A planar integrated circularly polarized magnetoelectric dipole antenna with a tooth-shaped opening, characterized in that: It comprises a first dielectric plate (1), a metal floor (2) and a second dielectric substrate (3) of the same size and tightly fitted from top to bottom; A pair of rotationally symmetrical tooth-shaped opening metal patches (5) are provided at the center of the upper surface of the first dielectric substrate (1), a certain spacing (6) is retained between the two tooth-shaped opening metal patches (5), and the tooth-shaped opening metal patches (5) have increased branches and cut corners (7). The tooth-shaped openings adjust the phase by changing the current flow path to optimize the circular polarization radiation performance. There are four tooth-shaped openings with a depth of 1.2 mm and a width of 1 mm. The first dielectric substrate (1) is provided with two rows of rotationally symmetrical metalized through holes (4) with the center of symmetry being the exact center of the first dielectric substrate (1). ), a total of 10, the metallized through holes (4) penetrate the tooth-shaped opening metal patch (5) and the metal floor (2), and connect the two; the spacing between the two rows of metallized through holes (4) is greater than the spacing (6) between the two tooth-shaped opening metal patches (5); a horizontally set gap (8) is etched in the center of the metal floor (2), the gap (8) is located directly below the two tooth-shaped opening metal patches (5) and is parallel to the long sides (10) of the two tooth-shaped opening metal patches (5), and the width of the gap (8) is greater than the spacing (6) between the two tooth-shaped opening metal patches (5); A microstrip feeding structure is provided on the lower surface of the second dielectric substrate (3). The microstrip feeding structure is a microstrip line (9) with an impedance of 50 ohms. The microstrip line (9) extends vertically from the edge of the second dielectric substrate (3) and extends beyond the bottom of the gap (8) of the metal floor (2).

2. The planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings according to claim 1, characterized in that: The tooth-shaped opening metal patch (5) has a tooth-shaped opening process.

3. The planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings according to claim 1, characterized in that: The flow direction of the current on the tooth-shaped opening metal patch (5) is adjusted by adjusting the length of the branches thereon, so that the overall flow direction of the current is parallel to the long side (10) of the tooth-shaped opening metal patch (5).

4. The planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings according to claim 1, characterized in that: Based on the basic principle of magnetoelectric dipole, two rows of metallized through holes (4) are used in a first dielectric plate (1) to simulate the vertical metal wall of a full-metal magnetoelectric dipole, so that an equivalent magnetic current is excited in the two rows of metallized through holes (4). By modifying the shapes of two tooth-shaped open metal patches (5), the current distribution thereon is optimized, so that the current and the equivalent magnetic current work together to generate two equal-amplitude orthogonal electric fields with a 90° phase difference, thereby realizing circularly polarized radiation.

5. The planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings according to claim 1, characterized in that: The energy of the microstrip line (9) is coupled to the metallized through hole (4) in the first dielectric plate (1) and the tooth-shaped opening metal patch (5) on the upper layer thereof through the gap (8), thereby exciting a circularly polarized radiation wave.

6. The planar integrated circularly polarized magnetoelectric dipole antenna with tooth-shaped openings according to claim 1, characterized in that: The antenna port adopts microstrip feeding mode, and the input impedance of the port is 50 ohms.

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