An X-band broadband circularly polarized magnetoelectric dipole antenna

Abstract

The application discloses an X-band broadband circularly polarized magnetoelectric dipole antenna and belongs to the technical field of microwave antennas. The X-band broadband circularly polarized magnetoelectric dipole antenna comprises, from top to bottom, an upper dielectric substrate, a semi-cured layer, a lower dielectric substrate and a metal ground back plate. The upper surface of the upper dielectric substrate is provided with four radiation patches arranged in a rectangular array, each radiation patch has a cross-shaped slot and a rectangular cut corner at the inner and outer top corners. The upper surface centers of the upper dielectric substrate and the lower dielectric substrate are respectively provided with spatially orthogonal upper and lower feed patches, the two are respectively connected with metal through holes and metal blind holes, and a double-L-shaped feed probe is formed, which is used for providing equal-amplitude and 90-degree phase-difference orthogonal excitation. The application has the advantages of wide frequency band, high isolation, flat gain and high circular polarization purity and is suitable for X-band broadband communication systems.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically relating to a broadband circularly polarized magnetoelectric dipole antenna in the X-band. Background Technology

[0002] Magnetoelectric dipole antennas, due to their ability to simultaneously excite equivalent magnetic and electric dipoles, naturally possess excellent characteristics such as wide bandwidth, equiplanar beamwidth, and low backlobe radiation. In modern complex communication environments, circularly polarized antennas are widely used because of their advantages such as effectively resisting multipath effects, overcoming Faraday rotation effects, and not requiring polarization alignment.

[0003] Traditional single-fed circularly polarized magnetoelectric dipole antennas typically achieve their performance by introducing perturbations (such as chamfering or slotting) into the structure. However, this method is limited by the singularity of the resonant characteristics, often resulting in a narrow axial ratio bandwidth. Using a dual-fed network to provide orthogonal excitations with equal amplitude and a 90-degree phase difference can significantly broaden the antenna's axial ratio bandwidth. However, introducing a dual-fed structure in a compact space can easily lead to strong electromagnetic coupling between the two feed ports, degrading port isolation and consequently affecting the performance of the feed network and the entire antenna system. Furthermore, the coordinated design of broadband impedance matching and polarization purity remains a current engineering challenge. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a broadband circularly polarized magnetoelectric dipole antenna in the X-band. This invention utilizes dual ports to introduce orthogonal excitation signals of equal amplitude and 90° phase to achieve circularly polarized radiation. Through the optimized multilayer substrate structure, radiating patch array, and the synergistic design of orthogonal dual L-shaped feed probes, it significantly improves the high isolation between the two feed ports while achieving wideband impedance matching and excellent circular polarization characteristics.

[0005] The objective of this invention is achieved as follows: A broadband circularly polarized magnetoelectric dipole antenna in the X-band includes an upper dielectric substrate, a prepreg layer, a lower dielectric substrate, and a metal ground backplate arranged sequentially from top to bottom; four radiating patches are disposed on the upper surface of the upper dielectric substrate. Four radiating patches are arranged in a rectangular array on the upper surface of the upper dielectric substrate; Each radiation patch is a rectangular patch with an inclined cross-shaped slit inside; the outer and inner corners of the rectangular patch are both rectangular chamfered, and the cross-shaped slits are connected to the rectangular chamfered. The upper surface center of the upper dielectric substrate and the upper surface center of the lower dielectric substrate are respectively provided with an upper feed patch and a lower feed patch; the upper feed patch and the lower feed patch are orthogonally distributed in space; One end of the upper feed patch is connected to a metal through-hole, and one end of the lower feed patch is connected to a metal blind hole; the ends of the metal through-hole and the metal blind hole are respectively fed through a coaxial line.

[0006] Furthermore, the four radiating patches are rotationally symmetrical.

[0007] Furthermore, the cross-shaped gap includes mutually perpendicular through-hole gaps and beveled gaps; Among them, the two ends of the through-hole gap connect the two rectangular chamfers opposite the rectangular patch, and the slanted gap is off the center of the rectangular patch and close to the outer top corner of the rectangular patch; The beveled gap extends to the edge of the rectangular patch.

[0008] Furthermore, both the upper and lower power feed patches are rectangular structures with semicircles connected at both ends.

[0009] Furthermore, each radiating patch has two metal pillars at its inner top corner, with the two metal pillars located on both sides of the through-hole. Each metal pillar penetrates vertically through the upper dielectric substrate, the prepreg layer, and the lower dielectric substrate, and is electrically connected to the metal ground plane.

[0010] Furthermore, both the upper and lower dielectric substrates are made of F4B material with a dielectric constant of 2.65. The semi-cured layer is made of FR-28 material with a dielectric constant of 2.74.

[0011] Furthermore, the metal via of the upper feed patch vertically penetrates the upper dielectric substrate, the prepreg layer, and the lower dielectric substrate; the upper feed patch and the metal via together form the first L-shaped feed probe. The metal blind via of the lower feed patch vertically penetrates the lower dielectric substrate, and the lower feed patch and the metal blind via together form a second L-shaped feed probe. The first L-shaped feed probe and the second L-shaped feed probe are fed through a coaxial line.

[0012] Furthermore, the metal backing plate is provided with two clearance holes, corresponding to a metal blind hole and a metal through hole respectively; the metal blind hole and the metal through hole pass through the corresponding clearance hole and do not contact the metal backing plate.

[0013] Compared with the prior art, the present invention has the following advantages: 1. Extremely wide effective overlap bandwidth: This invention achieves excellent impedance matching and polarization purity through the coordinated design of the cross-shaped slots, rectangular chamfers, and L-shaped feed probes in the radiating patch. The antenna's overlap impedance bandwidth ( The GHz band is 7.37-12.52 GHz, and the 3dB axial ratio bandwidth is 7.43-13.25 GHz. Its overall effective operating bandwidth is 7.43-12.52 GHz, with a relative bandwidth of approximately 51.0%.

[0014] 2. Excellent Port Isolation: Addressing the issue of strong coupling in dual-fed antennas, this invention effectively suppresses electromagnetic crosstalk through a feed patch design distributed across different dielectric substrate layers and spatially orthogonal. Within the effective operating frequency band, isolation remains at a low level, ensuring efficient independent operation during dual-port excitation.

[0015] 3. Easy to process and stable performance: The F4B and FR-28 multilayer lamination process is adopted, which has excellent radiation performance and greatly improves its applicability in broadband communication systems.

[0016] 4. High in-band gain and excellent flatness: The antenna designed in this invention maintains a stable gain between 6.6 dBi and 7.0 dBi across a wide frequency band from 7 GHz to 11 GHz, with minimal in-band gain fluctuation. The antenna exhibits extremely high radiation efficiency and excellent in-band performance consistency throughout the core X-band region, effectively avoiding signal fading problems caused by frequency jumps in broadband communication. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the three-dimensional structure of a broadband circularly polarized magnetoelectric dipole antenna in the X-band. Figure 2 This is an exploded perspective view of the structure of an X-band broadband circularly polarized magnetoelectric dipole antenna. Figure 3 This is a three-dimensional structural diagram of the two "L"-shaped feed probes and the metal through-holes of all the radiating patches of an X-band broadband circularly polarized magnetoelectric dipole antenna. Figure 4 This is a top view of the overall structure of an X-band broadband circularly polarized magnetoelectric dipole antenna; Figure 5 This is a top view of the two radiating patches of an X-band broadband circularly polarized magnetoelectric dipole antenna. Figure 6 This is a side view of the overall structure of an X-band broadband circularly polarized magnetoelectric dipole antenna; Figure 7 This is a top view of the feed patch of an X-band broadband circularly polarized magnetoelectric dipole antenna. Figure 8 This is a graph showing the reflection coefficient of two ports of an X-band broadband circularly polarized magnetoelectric dipole antenna as a function of frequency. Figure 9It is the isolation between the two ports of the X-band broadband circularly polarized magnetoelectric dipole antenna; Figure 10 This is a gain curve of a broadband circularly polarized magnetoelectric dipole antenna in the X-band. Figure 11 This is a schematic diagram of the axial ratio of a broadband circularly polarized magnetoelectric dipole antenna in the X-band. Figure 12 This is the radiation pattern of the xoz plane of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 8 GHz. Figure 13 This is the yoz plane radiation pattern of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 8 GHz. Figure 14 This is the radiation pattern of the xoz plane of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 9 GHz. Figure 15 This is the yoz plane radiation pattern of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 9 GHz. Figure 16 This is the radiation pattern of the xoz plane of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 10 GHz. Figure 17 This is the yoz plane radiation pattern of a broadband circularly polarized magnetoelectric dipole antenna in the X-band at 10 GHz. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. It should be understood that the following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Equivalent modifications, structural substitutions, or parameter adjustments made by those skilled in the art based on the content disclosed in this invention should all fall within the scope of protection of this invention.

[0019] See Figures 1 to 7 This invention provides a broadband circularly polarized magnetoelectric dipole antenna in the X-band, comprising, from top to bottom, an upper dielectric substrate 3, a prepreg layer 4, a lower dielectric substrate 5, and a metal ground plane 6. Four radiating patches 2 are disposed on the upper surface of the upper dielectric substrate 3, arranged in a rectangular array and exhibiting rotational symmetry.

[0020] Each radiating patch 2 has a rectangular body with an inclined cross-shaped slit inside. Rectangular chamfers are provided at both the outer and inner corners of the rectangular patch, and the cross-shaped slits are connected to these chamfers. Furthermore, the cross-shaped slits include mutually perpendicular through-hole slits and beveled slits; wherein the two ends of the through-hole slit connect to the two opposite rectangular chamfers of the rectangular patch, and the beveled slits are offset from the center of the rectangular patch and close to its outer corner, extending to the edge of the rectangular patch.

[0021] See Figure 5 Each radiating patch 2 has two metal pillars 7 at its inner apex, located on either side of the through-hole. Each metal pillar 7 vertically penetrates the upper dielectric substrate 3, the prepreg layer 4, and the lower dielectric substrate 5, and is electrically connected to the metal ground backplate 6 to achieve electrical coupling between the radiating patch 2 and the ground, while also participating in the excitation of the magnetic dipole.

[0022] See Figure 3 , Figure 4 and Figure 7 An upper-layer feed patch 1 and a lower-layer feed patch 10 are respectively disposed at the center of the upper surface of the upper dielectric substrate 3 and the center of the upper surface of the lower dielectric substrate 5. Both the upper-layer feed patch 1 and the lower-layer feed patch 10 are rectangular structures with semi-circular ends connected together, and they are orthogonally distributed in space. A metal through-hole 8 is connected to the bottom of one end of the upper-layer feed patch 1, and a metal blind via 9 is connected to the bottom of one end of the lower-layer feed patch 10. The ends of the metal through-hole 8 and the metal blind via 9 are fed through coaxial lines, respectively forming a first L-shaped feed probe and a second L-shaped feed probe.

[0023] Specifically, the metal via 8 vertically penetrates the upper dielectric substrate 3, the prepreg layer 4, and the lower dielectric substrate 5, forming a first L-shaped feed probe together with the upper feed patch 1; the metal blind via 9 vertically penetrates the lower dielectric substrate 5, forming a second L-shaped feed probe together with the lower feed patch 10. The two L-shaped feed probes are used to provide orthogonal excitation signals of equal amplitude and 90° phase difference, thereby achieving circularly polarized radiation.

[0024] See Figure 6 The metal grounding backplate 6 is provided with two clearance holes, which correspond to the metal blind hole 9 and the metal through hole 8 respectively, so that when the metal blind hole 9 and the metal through hole 8 pass through the corresponding clearance holes, they do not come into contact with the metal grounding backplate 6, thereby avoiding short circuits.

[0025] In this preferred embodiment, both the upper dielectric substrate 3 and the lower dielectric substrate 5 are made of F4B material with a dielectric constant of 2.65, and the semi-cured layer 4 is made of FR-28 material with a dielectric constant of 2.74, with a thickness of 0.1 mm. The selection of these materials and the lamination process ensure structural consistency and electrical performance stability.

[0026] In this embodiment, the cross-shaped slot of the radiating patch 2 physically divides a single radiating patch into two structurally similar sub-patterns. The introduction of the cross-shaped slot, on the one hand, excites a new resonant frequency, effectively expanding the impedance bandwidth of the antenna; on the other hand, it changes the current path on the surface of the radiating patch 2, guiding the surface current to rotate in each operating cycle, thereby achieving stable and pure broadband circularly polarized radiation characteristics.

[0027] The independently configured upper feed patch 1 and lower feed patch 10, despite the slight difference in their spatial hierarchy resulting in slightly different impedance matching characteristics (i.e., reflection coefficient curves) at the two feed ports, still achieve excellent bandwidth overlap. Specifically, the overlap impedance bandwidth of this antenna ( The antenna's overall effective relative operating bandwidth is highly synergistic with the 3dB axial ratio bandwidth (7.43 GHz to 13.25 GHz), resulting in a final overall effective relative operating bandwidth of approximately 51.0%.

[0028] The antenna exhibits excellent and stable spatial radiation characteristics within its core operating frequency bands (8 GHz, 9 GHz, and 10 GHz). On the two orthogonal principal planes, the antenna's main polarization beamform remains highly symmetrical, and it demonstrates significant polarization isolation in the direction of maximum radiation (0°). Cross-polarization levels are effectively suppressed, ensuring high circular polarization purity in spatial radiation. Simultaneously, thanks to the synergistic excitation mechanism of magnetic and electric dipoles, the antenna's backlobe radiation is greatly weakened, achieving an excellent front-to-back ratio and efficiently and directionally concentrating electromagnetic energy in the upper half of space.

[0029] As a specific implementation example, the geometric dimensions (in millimeters) of each component in this embodiment are as follows (see...). Figures 1 to 7 (Dimensions in the text) The lengths of a, b, c, d, e, g, h, and q are 18.75, 5.25, 1.875, 4.375, 6.25, 6.5625, 0.625, 0.3125, 0.625, 4.779, 3.556, 4.672, 1.016, 1, 3.6875, and 1.5625 respectively. It should be noted that the above dimensions are a design example for a specific center frequency in the X-band (e.g., 10 GHz). If it is necessary to cover different sub-bands or adapt to different center frequencies, those skilled in the art can use conventional electromagnetic simulation methods to scale or fine-tune the above parameters proportionally, and these adjustments still fall within the protection scope of this invention.

[0030] See Figures 8 to 17 The simulation and test results are shown below: Figure 8 The reflection coefficients of the two ports are shown. , The impedance matching curves for the frequency variation are all below -10 dB in the range of 7.37 GHz to 12.52 GHz, indicating good impedance matching. Figure 9The isolation between the two ports is shown to remain at a low level throughout the entire operating frequency band, demonstrating that the dual-fed structure has excellent high isolation characteristics. Figure 10 The antenna gain curves are shown, with the gain remaining stable between 6.6 dBi and 7.0 dBi in the 7 GHz to 11 GHz band, exhibiting excellent in-band gain flatness. Figure 11 The curves showing the axial ratio (AR) as a function of frequency are presented, with a 3 dB axial ratio bandwidth ranging from 7.43 GHz to 13.25 GHz; Figures 12 to 17 The radiation patterns of the antenna in the xoz and yoz planes at frequencies of 8 GHz, 9 GHz, and 10 GHz are shown respectively. The main polarization beam is symmetrical, cross-polarization is well suppressed, and the back lobe radiation is low, which fully demonstrates the excellent radiation characteristics of the magnetoelectric dipole antenna.

[0031] In summary, the X-band broadband circularly polarized magnetoelectric dipole antenna proposed in this invention achieves effective overlap of wide impedance bandwidth (7.37–12.52 GHz) and wide axial ratio bandwidth (7.43–13.25 GHz) through the synergistic design of the cross-shaped slot and rectangular chamfer structure of the radiating patch, the spatially orthogonally distributed double-layer L-shaped feed probes, and the multilayer dielectric substrate and the metal ground plane 6. The overall relative bandwidth is approximately 51.0%. Simultaneously, it exhibits excellent isolation between the two ports, flat gain, symmetrical radiation pattern, and good circular polarization purity, making it suitable for various X-band broadband communication systems.

[0032] The above description is merely a preferred embodiment of the present invention and does not limit the scope of the patent. Any equivalent structural substitutions or parameter adjustments made based on the description and drawings of this invention should be considered within the protection scope of this invention.

Claims

1. A broadband circularly polarized magnetoelectric dipole antenna in the X-band, comprising, from top to bottom, an upper dielectric substrate (3), a prepreg layer (4), a lower dielectric substrate (5), and a metal ground plane (6); characterized in that, The upper surface of the upper dielectric substrate (3) is provided with four radiating patches (2); Four radiating patches (2) are arranged in a rectangular array on the upper surface of the upper dielectric substrate (3); Each radiation patch (2) has a rectangular patch as its main body, and the rectangular patch has an inclined cross-shaped slit inside; the outer and inner corners of the rectangular patch have rectangular chamfers, and the cross-shaped slits are connected to the rectangular chamfers. The upper surface center of the upper dielectric substrate (3) and the upper surface center of the lower dielectric substrate (5) are respectively provided with an upper feed patch (1) and a lower feed patch (10); the upper feed patch (1) and the lower feed patch (10) are orthogonally distributed in space; One end of the upper feed patch (1) is connected to a metal through hole (8), and one end of the lower feed patch (10) is connected to a metal blind hole (9); the ends of the metal through hole (8) and the metal blind hole (9) are respectively fed through a coaxial line.

2. The broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, The four radiating patches (2) are rotationally symmetrical.

3. The broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, The cross-shaped gap includes mutually perpendicular through-hole gaps and beveled gaps; Among them, the two ends of the through-hole gap connect the two rectangular chamfers opposite the rectangular patch, and the slanted gap is off the center of the rectangular patch and close to the outer top corner of the rectangular patch; The beveled gap extends to the edge of the rectangular patch.

4. The broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, Both the upper feed patch (1) and the lower feed patch (10) are rectangular structures with semicircles connected at both ends.

5. A broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, Two metal pillars (7) are provided at the inner top corner of each radiation patch (2), and the two metal pillars (7) are located on both sides of the through-hole; Each metal pillar (7) penetrates vertically through the upper dielectric substrate (3), the semi-cured layer (4) and the lower dielectric substrate (5), and is electrically connected to the metal ground backplate (6).

6. The broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, The upper dielectric substrate (3) and the lower dielectric substrate (5) are both made of F4B material with a dielectric constant of 2.65; The semi-cured layer (4) is made of FR-28 material with a dielectric constant of 2.

74.

7. The X-band broadband circularly polarized magnetoelectric dipole antenna according to claim 1, characterized in that, The metal via (8) of the upper feed patch vertically penetrates the upper dielectric substrate (3), the semi-cured layer (4) and the lower dielectric substrate (5); the upper feed patch (1) and the metal via (8) together form the first L-shaped feed probe; The metal blind hole (9) of the lower feed patch vertically penetrates the lower dielectric substrate (5), and the lower feed patch (10) and the metal blind hole (9) together form the second L-shaped feed probe. The first L-shaped feed probe and the second L-shaped feed probe are fed through a coaxial line.

8. A broadband circularly polarized magnetoelectric dipole antenna in the X-band according to claim 1, characterized in that, The metal backplate (6) is provided with two clearance holes, which correspond to the metal blind hole (9) and the metal through hole (8) respectively; the metal blind hole (9) and the metal through hole (8) pass through the corresponding clearance holes and do not contact the metal backplate (6).

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