Omnidirectional-radiation low-cross-polarization magnetic dipole antenna

Abstract

The invention relates to the technical field of antennas, and provides an omnidirectional-radiation low-cross-polarization magnetic dipole antenna, and conductive via holes formed in two sides form a substrate integrated waveguide boundary to suppress transverse electromagnetic leakage and contribute to limiting disturbance of current distribution in the vertical direction, so that transverse cross-polarization radiation is controlled; a longitudinal narrow gap is formed in the central axis of the patch, and a transverse narrow gap is formed in the vertical direction of the patch. Symmetrical positions of the longitudinal narrow slits and a slit arrangement mode orthogonal to the longitudinal narrow slits form a symmetrical coupling structure. The symmetry can effectively balance current excitation, so that a cross polarization component caused by asymmetric radiation is weakened. A feeding point is located on one side of the longitudinal narrow gap, so that current excitation is more concentrated, and a stable current path and symmetrical electric field distribution are conveniently formed.

Description

Technical Field

[0001] This disclosure relates to the field of antenna-related technology, and more specifically, to an omnidirectional, low-cross-polarization magnetic dipole antenna. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] With the rapid development of wireless communication technology, wearable devices and various handheld terminal devices are constantly emerging, placing higher demands on the performance and miniaturization of the antennas equipped in these devices. Especially in WLAN (Wireless Local Area Network) applications, omnidirectional antennas, due to their ability to achieve relatively uniform signal reception and transmission in all directions, have become a key component for achieving efficient wireless communication. In highly integrated communication terminals, antenna solutions that combine miniaturization and omnidirectional radiation characteristics have significant application value.

[0004] Existing USB network card antennas mostly employ a folded monopole structure. While this type of antenna is simple in structure, it suffers from a high cross-polarization level, which easily leads to signal interference and degrades communication quality. Furthermore, traditional antennas are relatively large, hindering compact integration in space-constrained terminal devices. Therefore, achieving antenna miniaturization and low cross-polarization while maintaining good omnidirectional radiation performance remains a major technical challenge in current wireless communication terminal antenna design. Summary of the Invention

[0005] To address the aforementioned problems, this disclosure proposes an omnidirectional, low-cross-polarization magnetic dipole antenna, which enables antenna miniaturization and low cross-polarization.

[0006] To achieve the above objectives, the present disclosure adopts the following technical solution: One or more embodiments provide an omnidirectional radiating low cross-polarization magnetic dipole antenna, including a dielectric substrate, a patch, and a metal ground plane; the patch is disposed on the upper surface of the dielectric substrate, and the metal ground plane is disposed on the lower surface of the dielectric substrate; A row of conductive vias is provided on each of the opposite two sides of the dielectric substrate. The conductive vias on both sides of the patch are electrically connected to the metal ground plane to form a substrate integrated waveguide structure. Parallel to the direction of the conductive via arrangement, a longitudinal narrow slit is opened on the central axis of the patch, and multiple transverse narrow slits are arranged vertically outward from the longitudinal narrow slit; a feed point is provided on one side of the longitudinal narrow slit on the patch, and an annular slit is arranged around the feed point.

[0007] Compared with the prior art, the beneficial effects of this disclosure are as follows: The magnetic dipole antenna disclosed herein uses conductive vias on both sides to form the substrate integrated waveguide boundary, suppressing lateral electromagnetic leakage and helping to limit current distribution disturbances in the vertical direction, thereby controlling lateral cross-polarization radiation. A longitudinal narrow slot is formed on the central axis of the patch, and a lateral narrow slot is arranged perpendicular to it. The symmetrical position of the longitudinal narrow slot and the orthogonal arrangement of the slots form a symmetrical coupling structure. This symmetry effectively balances the current excitation, thereby reducing the cross-polarization component caused by asymmetric radiation. The feed point is located on one side of the longitudinal narrow slot, making the current excitation more concentrated and facilitating the formation of a stable current path and a symmetrical electric field distribution.

[0008] The advantages of this disclosure, as well as its additional advantages, will be described in detail in the following specific embodiments. Attached Figure Description

[0009] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute a limitation thereof.

[0010] Figure 1 This is a schematic diagram of the patch surface of the magnetic dipole antenna according to Embodiment 1 of this disclosure; Figure 2 This is a three-dimensional structural schematic diagram of the magnetic dipole antenna of Embodiment 1 of this disclosure; Figure 3 This is a schematic diagram of the metal ground side of the magnetic dipole antenna according to Embodiment 1 of this disclosure; Figure 4 This is a top view of the surface current distribution of the magnetic dipole antenna according to Embodiment 1 of this disclosure; Figure 5 This is a three-dimensional schematic diagram of the surface current distribution of the magnetic dipole antenna according to Embodiment 1 of this disclosure; Figure 6 This is a graph showing the relationship between the antenna port reflection coefficient and frequency in Embodiment 1 of this disclosure; Figure 7 This is the far-field radiation pattern of the antenna in Embodiment 1 of this disclosure; Figure 8 This is the H-plane far-field radiation pattern of the antenna of Embodiment 1 of this disclosure; Figure 9 This is a graph showing the relationship between antenna gain and antenna resonant frequency in Embodiment 1 of this disclosure; Among them: 1. dielectric substrate; 2. patch; 3. conductive via; 4. lateral narrow gap; 5. longitudinal narrow gap; 6. metal ground; 7. coaxial power supply port; 8. power supply point; 9. annular gap. Detailed Implementation

[0011] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0012] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0013] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features within those embodiments can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0014] Omnidirectional radiation: refers to an antenna having approximately uniform radiation gain (0-360°) in the horizontal direction, which is suitable for scenarios such as mobile communication and WLAN that require multi-directional signal reception / transmission; Low cross-polarization: The low cross-polarization level of the antenna helps to improve polarization purity and signal stability. The electric field symmetry is controlled by symmetrical structural design (slots, feed, SIW layout), which reduces polarization mismatch, improves communication quality, and reduces interference.

[0015] Example 1 In one or more of the technical solutions disclosed in the embodiments, such as Figures 1 to 9 As shown, an omnidirectional, low-cross-polarization magnetic dipole antenna includes a dielectric substrate 1, a patch 2, and a metal ground plane 6; the patch 2 is disposed on the upper surface of the dielectric substrate 1, and the metal ground plane 6 is disposed on the lower surface of the dielectric substrate 1. A row of conductive vias 3 is provided on each of the opposite sides of the dielectric substrate 1. The conductive vias 3 on both sides of the patch 2 are electrically connected to the metal ground plane 6 to form a substrate integrated waveguide (SIW) structure. In the direction parallel to the arrangement of conductive vias 3, a longitudinal narrow slit 5 is opened on the central axis of the patch 2, and multiple transverse narrow slits 4 are arranged vertically outward from the longitudinal narrow slit 5; a power supply point 8 is provided on one side of the longitudinal narrow slit 5 on the patch 2, and an annular slit 9 is arranged around the power supply point 8.

[0016] In this embodiment, the magnetic dipole antenna has conductive vias 3 on both sides forming the substrate integrated waveguide boundary, suppressing lateral electromagnetic leakage and helping to limit current distribution disturbances in the vertical direction, thereby controlling lateral cross-polarization radiation. A longitudinal narrow slot 5 is formed on the central axis of the patch 2, and a lateral narrow slot 4 is arranged in its vertical direction. The symmetrical position of the longitudinal narrow slot 5 and the arrangement of the orthogonal lateral narrow slots 4 form a symmetrical coupling structure. This symmetry can effectively balance the current excitation, thereby reducing the cross-polarization component caused by asymmetric radiation. The feed point 8 is located on one side of the longitudinal narrow slot 5, making the current excitation more concentrated and facilitating the formation of a stable current path and a symmetrical electric field distribution.

[0017] In some embodiments, the patch 2 and the metal ground 6 are made of conductive materials and may be made of conductive metal sheet structures; Optionally, the dielectric substrate 1 can be F4B-2, with a relative permittivity of 2.65 and a loss tangent of 0.003; A further technical solution is that multiple transverse narrow slits 4 of equal size are provided on the patch 2 extending vertically outward from the longitudinal narrow slit 5. The equal size includes equal length and equal width; the transverse narrow slits 4 are perpendicular to the longitudinal narrow slit 5. This implementation design incorporates multiple horizontal narrow slots 4 of uniform size on a rectangular patch 2, arranged perpendicular to the vertical narrow slots 5 located on the central axis. These slots, through their coplanar distribution, form a balanced electromagnetic coupling structure, each responding to the current generated at the feed point 8, creating multiple local radiating elements perpendicular to the direction of the vertical narrow slots 5. The uniform size ensures consistent resonant response of each slot at the same frequency, contributing to a consistent current distribution and symmetrical radiation waveform. The vertical arrangement minimizes electromagnetic mutual coupling between slots, while simultaneously superimposing an approximately circular omnidirectional radiation pattern in different directions. This slot combination works synergistically, enhancing the antenna's radiation intensity and consistency in the horizontal plane.

[0018] The design of a transverse narrow slot 4 with a uniform size and a vertical narrow slot 5 results in more stable omnidirectional radiation performance for the antenna, significantly suppressing polarization interference in the direction of the main slot and improving radiation symmetry. This structure is beneficial for improving radiation efficiency and reducing cross-polarization levels, thereby improving communication quality. The uniform size design also facilitates standardized etching templates and layouts during mass production, improving process controllability and consistency, and reducing manufacturing costs. In addition, the vertical arrangement allows for the spatial superposition of multiple approximately equivalent radiating elements within the frequency band, improving the uniformity of the radiation pattern.

[0019] In some embodiments, five transverse narrow slits 4 are provided, wherein four transverse narrow slits 4 are symmetrically arranged at both ends of the longitudinal narrow slits 5; and the fifth transverse narrow slit 4 is arranged at the middle of the longitudinal narrow slits 5. A further technical solution involves setting a power supply point 8 on the patch 2, with the longitudinal narrow gap 5 as the axis of symmetry and the fifth transverse narrow gap 4 as the symmetry line; In one specific implementation, patch 2 adopts an arbitrary symmetrical shape, such as a polygon or a symmetrical arc shape; preferably, in this embodiment, patch 2 is a rectangular patch, and the annular gap 9 surrounding the feed point 8 is a square. The rectangular ring slot 9 on the metal patch 2 serves to introduce capacitive reactance and adjust the antenna impedance matching performance.

[0020] In the above embodiment, the annular slot 9 is arranged around the feed point 8 to form a closed square annular structure, which can excite a closed annular current. The annular current generates a radiation field dominated by a magnetic dipole, which inherently has low cross-polarization, achieving effective coupling of electromagnetic energy. By arranging the feed point 8 on one side of the longitudinal narrow slot 5, which serves as the main slot, and combining it with the square annular slot 9 centered on it, a more concentrated energy injection point and a more efficient radiation coupling structure can be achieved, effectively improving radiation efficiency and input impedance matching performance. The closed square ring with equal sides helps to form a stable and symmetrical annular current path, thereby further optimizing the magnetic dipole characteristics of the antenna and enhancing its omnidirectional radiation capability. The structural symmetry also helps to control the cross-polarization component and improve the balance of the radiation pattern. In addition, this structure is suitable for area-constrained applications, achieving a balance between size compression and performance assurance through the extension of the annular current path.

[0021] Five narrow transverse slots 4 are the preferred embodiment, which can be adjusted appropriately according to frequency response and radiation pattern design requirements. For example, the number can be increased to seven to enhance omnidirectionality, or reduced to three to compress structural dimensions. At the same time, the length and width of the slots can also be adjusted to optimize the resonant frequency and bandwidth.

[0022] In some embodiments, conductive material can be laid around the periphery of the conductive via 3, and conductive metal material can be used to form a metallized via. In one possible implementation, the longitudinal narrow slit 5 and the transverse narrow slit 4 are formed on the patch 2 by etching. In the above embodiments, the specific slot structure design of the rectangular patch 2 effectively excites a radiation mode similar to a magnetic dipole. The narrow slot 5, located on the central axis, forms a symmetrical excitation structure, effectively suppressing cross-polarization components. The five narrow slots 4, evenly arranged vertically, couple with it, further optimizing radiation performance and enhancing the antenna's current symmetry and amplitude consistency in the vertical direction. The rectangular ring slots 9 are distributed around the feed point 8, generating local ring current paths under the excitation of the feed point 8, enhancing magnetic field coupling capability. The metal ground planes 6 on the upper and lower surfaces and the rectangular patch 2 together constitute the planar electromagnetic field boundary, ensuring stable electromagnetic mode transmission.

[0023] This implementation achieves omnidirectional radiation characteristics of the antenna and effectively reduces cross-polarization levels through meticulous design of the slot location, shape, and number, thereby improving signal purity and anti-interference capabilities. The introduction of the SIW structure improves the concentrated transmission efficiency of electromagnetic energy, reduces the space occupied by the structure, and facilitates antenna miniaturization design. In addition, the rectangular ring slot 9 structure provides good matching for the feed point, improving overall radiation efficiency.

[0024] In a further technical solution, a row of conductive vias 3 is provided on each of the opposite two sides of the dielectric substrate 1, and the conductive vias 3 are distributed at equal intervals. This embodiment introduces equally spaced conductive vias 3 into the SIW structure design of the antenna. The conductive vias 3 are uniformly arranged along the two symmetrical edges of the rectangular patch 2 and perpendicularly connected to the metal ground plane 6, forming a regular and continuous electromagnetic shielding structure. This equally spaced arrangement ensures the continuity and symmetry of the waveguide boundary current, effectively suppressing undesirable leakage modes and edge radiation. Simultaneously, the equally spaced arrangement enhances the periodicity of the SIW channel, which is beneficial for forming stable fundamental mode propagation characteristics, further improving the overall radiation symmetry and structural electromagnetic consistency of the antenna.

[0025] The use of equally spaced metallized vias significantly improves the uniformity of antenna radiation performance and reduces cross-polarization components caused by lateral current non-uniformity. This structural optimization enhances the antenna's omnidirectional performance and further strengthens its spatial radiation consistency. Furthermore, the equally spaced arrangement simplifies the PCB manufacturing process, helping to improve processing consistency and yield in actual production, thereby enhancing the antenna's applicability and reliability in low-cost mass production.

[0026] In one possible implementation, the antenna area is 9.1mm × 9.1mm, equivalent to 0.176λ0 × 0.176λ0 (where λ0 is the wavelength of electromagnetic waves in vacuum); the overall thickness is 2mm; the dielectric substrate 1 used is a square structure with a side length of 9.1mm. The conductive vias 3 are all evenly spaced, with a via spacing of 0.91mm; the distance from the feed point 8 to the edge of the longitudinal narrow slit 5 on the central axis is d = 1.35mm, and the radius of the inner conductor of the connected coaxial line is 0.3mm; The longitudinal narrow slit 5 on the central axis of patch 2 has a length of 9.1 mm and a width of 0.2 mm; The five transverse narrow slits perpendicular to the central axis are 3.8 mm long and 0.3 mm wide; The annular gap 9 of the square ring structure surrounding the feed point 8 has a side length of 2mm and a gap width of 0.1mm.

[0027] In this specific structural design example, the antenna area is controlled at 9.1mm × 9.1mm. By selecting a high dielectric constant material and combining it with the SIW structure, the propagation path of electromagnetic waves in the medium is effectively compressed, achieving size reduction. The 2mm antenna thickness ensures stable support between the microstrip layer and the metal ground plane, while balancing mechanical strength and electromagnetic characteristics. The square dielectric substrate structure contributes to the symmetrical design of antenna performance, thereby obtaining an ideal radiation pattern and polarization characteristics. Compared to typical wireless LAN terminal antennas, this antenna exhibits omnidirectional radiation characteristics, low cross-polarization level, and a maximum cross-polarization level in the E-plane of [value missing]. 42.5dB, maximum cross-polarization of H-plane is The antenna exhibits a 55dB gain, a 3dB beamwidth of 360°, and a maximum gain of 2.7dBi. This embodiment boasts a highly compact antenna structure with an area of ​​only 0.176λ0 × 0.176λ0 (λ0 is the wavelength of electromagnetic waves in vacuum). Given the advantages of these antenna radiation characteristics and its miniaturized structure, it meets the application requirements of portable communication devices such as USB wireless network cards.

[0028] In some embodiments, an antenna SMA coaxial probe is provided for feeding at the feed point 8, and a coaxial feed port 7 is provided on the metal ground 6; An SMA coaxial probe is a component of a standard SMA coaxial connector used for coaxial probe feeding.

[0029] Optionally, the distance d from the feed point to the edge of the gap in the central axis is 1.35mm, and the radius of the inner conductor of the connected coaxial line is 0.3mm.

[0030] Traditional folded monopole antennas primarily rely on electric dipole radiation, with current concentrated on a vertical conductor, resulting in a single polarization direction and a tendency to induce cross-polarization. This embodiment, however, employs slot excitation to generate a ring current, forming a magnetic dipole radiation source. This source possesses natural horizontal radiation symmetry, significantly suppressing cross-polarization components. The design of the slot location, number, and size ensures balanced current paths in all directions, avoiding asymmetric electric fields caused by uneven excitation. The square ring slots, symmetrical slot array, and equally spaced vias together constitute a structurally highly symmetrical electromagnetic radiation unit, effectively improving the roundness and polarization purity of the antenna pattern.

[0031] like Figure 4 and 5 The figure shown is a surface current distribution diagram of the miniaturized low cross-polarization substrate integrated waveguide magnetic dipole antenna with omnidirectional radiation in this embodiment. Figure 4 The top view shows that the current distribution is characterized by excellent consistency in current direction. Studies have shown that five horizontally arranged narrow slits 4 perpendicular to the central axis can improve current consistency and reduce cross-polarization radiation. Figure 5As can be seen from the 3D view, the current flows from the upper metal patch 2 through the metallized via array to the lower conductor (metal ground 6), and then from the lower conductor to the upper conductor through the metallized via array, thus forming a current loop. Since the longitudinal narrow slot 5 is perpendicular to the current flow direction, according to the Love equivalent principle, this slot is equivalent to a magnetic current source, that is, the antenna is a magnetic dipole antenna. In addition, since the size of the metal ground is very small (only 0.176λ0 × 0.176λ0), the mirror effect of the equivalent magnetic dipole is not obvious, and the gain is not significantly improved compared with the classical dipole antenna.

[0032] Figure 6 The antenna port reflection coefficient S11 versus frequency provided for this embodiment shows that, within the range of 5.72~5.87GHz, |S11| ≤ 10 dB. This indicates that the antenna operates with a bandwidth of 150MHz and covers the 5.8GHz operating frequency band of wireless LANs.

[0033] Figure 7 The E-plane far-field radiation pattern of the antenna provided for this implementation case includes important parameters such as main polarization, cross polarization, 3dB beamwidth, and maximum gain. The omnidirectional maximum cross polarization level is... With a gain of 42.5dB and a 3dB beamwidth of 360°, and a maximum gain of 2.7dBi, it meets the short-range coverage requirements of wireless LANs, such as unobstructed areas within 10 meters.

[0034] The E-plane (Electric Field Plane) contains the plane of the antenna's main radiation direction and the electric field vector (E), and describes the distribution of antenna radiation along the electric field direction as the angle changes.

[0035] Figure 8 The H-plane far-field radiation pattern of the antenna provided for the implementation case includes important parameters such as main polarization, cross polarization, 3dB beamwidth, and maximum gain. The omnidirectional maximum cross polarization level is [value missing]. With a beamwidth of 360° and a gain of 55dB, the maximum gain is 2.7dBi, meeting the short-range coverage requirements of wireless LANs.

[0036] The H-plane (Magnetic Field Plane) contains the antenna's main radiation direction and the magnetic field vector (H), describing the distribution of antenna radiation along the magnetic field direction as the angle changes.

[0037] Figure 9 The antenna gain versus frequency diagram provided for the embodiments of the present invention shows that the gain is greater than 2.2 dBi within the range of 5.72 to 5.87 GHz, which meets the short-range coverage requirements of wireless local area networks.

[0038] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0039] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. An omni-directional radiating low cross-polarized magnetic dipole antenna, characterized by: The medium substrate, the patch and the metal ground are included; the patch is arranged on the upper surface of the medium substrate, and the metal ground is arranged on the lower surface of the medium substrate; The opposite two side edges of the medium substrate are respectively provided with a row of conductive vias, and the two side edges of the patch are respectively electrically connected with the metal ground through the conductive vias, thereby forming a substrate integrated waveguide structure. A longitudinal narrow gap is arranged on the central axis of the patch in a direction parallel to the arrangement of the row of conductive vias, and a plurality of transverse narrow gaps are arranged outwardly and perpendicularly from the longitudinal narrow gap; a feeding point is arranged on one side of the longitudinal narrow gap of the patch, and a ring gap is arranged around the feeding point.

2. A low cross-polar omnidirectional magnetic dipole antenna as claimed in claim 1, characterized in that: The patch and the metal ground adopt a conductive metal sheet structure.

3. The omni-directionally radiating low cross-polarized magnetic dipole antenna of claim 1, wherein: A plurality of transverse narrow gaps of equal size are arranged outwardly and perpendicularly from the longitudinal narrow gap on the patch, and the equal size includes equal length and equal width.

4. A magnetic dipole antenna with omni-directional radiation and low cross-polarization as claimed in claim 3, characterized in that: Five transverse narrow gaps are arranged, four of which are symmetrically arranged at both ends of the longitudinal narrow gap, and the fifth transverse narrow gap is arranged at the middle position of the longitudinal narrow gap.

5. A low cross-polar omnidirectional radiating magnetic dipole antenna as claimed in claim 4, characterized in that: A feeding point is arranged on the patch on the symmetry line of the fifth transverse narrow gap with the longitudinal narrow gap as the symmetry axis.

6. A low cross-polar omnidirectional radiating magnetic dipole antenna as claimed in claim 1, characterized in that: The patch adopts a rectangular patch, and the ring gap around the feeding point is a square.

7. A low cross-polar omnidirectional magnetic dipole antenna as claimed in claim 1, characterized in that: The opposite two side edges of the medium substrate are respectively provided with a row of conductive vias, and the conductive vias are arranged at equal intervals.

8. A magnetic dipole antenna with omni-directional radiation and low cross-polarization as claimed in claim 1, characterized in that: An antenna SMA coaxial probe feeding is arranged at the feeding point, and a coaxial feeding port is arranged on the metal ground.

9. A magnetic dipole antenna with omni-directional radiation and low cross-polarization as claimed in claim 1, characterized in that: The medium substrate has a square structure with a side length of 9.1 mm; the conductive vias are arranged at equal intervals, and the interval between the conductive vias is 0.91 mm; and the distance between the feeding point and the edge of the longitudinal narrow gap on the central axis is 1.35 mm.

10. A low cross-polar omnidirectional radiating magnetic dipole antenna as claimed in claim 1, characterized in that: The longitudinal narrow gap and the transverse narrow gap are arranged on the patch by etching.

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