A planar dual-fed circularly polarized antenna based on equal-amplitude and in-phase feeding

Abstract

The application discloses a planar dual-fed circularly polarized antenna based on equal-amplitude and in-phase feeding, which comprises a dielectric substrate and a metal floor, a monopole antenna and a dipole antenna which are printed on the upper surface of the dielectric substrate; the port 1 of the monopole antenna is connected with a T-shaped branch and the metal floor through the inner core and the outer conductor of a coaxial line to realize monopole antenna feeding and realize common-mode operation; the port 2 of the dipole antenna is connected with the metal at the two ends of a gap in a long branch through the inner core and the outer conductor of a coaxial line to realize dipole antenna feeding and realize differential-mode operation; based on the orthogonality and 90-degree phase difference of the common mode and the differential mode, when the monopole antenna and the dipole antenna are fed with equal amplitude and in-phase through the port 1 and the port 2, the dual-fed antenna realizes circularly polarized radiation. The antenna has the advantages of simple structure, wide frequency band and bidirectional circularly polarized radiation and is suitable for use in the fields of future mobile communication, wireless local area network and global positioning system.

Description

Technical Field

[0001] This invention relates to antenna design technology in the field of wireless communication, and particularly to a planar doubly-fed circularly polarized antenna with equal amplitude and in-phase feeding. Background Technology

[0002] Modern communication systems require stable communication in complex electromagnetic environments, which places high demands on the stability and anti-interference capabilities of antennas. Circular polarization, due to its advantages such as avoiding polarization loss, suppressing multipath interference, and mitigating the Faraday rotation effect of the ionosphere, is widely used in mobile communications, wireless local area networks, and global positioning systems.

[0003] Traditional dual-fed antennas require dual-port equal amplitude and a 90° phase difference for feeding to achieve circularly polarized radiation. Therefore, additional phase shift structures or devices are needed to achieve the 90° phase shift, which increases the space occupied by the antenna feeding structure and the design complexity.

[0004] Therefore, this invention proposes a planar dual-fed circularly polarized antenna based on equal amplitude and in-phase feeding, which solves the problem that existing dual-fed circularly polarized antennas require additional phase shift structures or devices, and simplifies the feeding structure of dual-fed circularly polarized antennas. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a planar dual-fed circularly polarized antenna based on equal-amplitude and in-phase feeding. By feeding the antenna with equal amplitude and in-phase feed at two ports, the common-mode operation of the monopole antenna and the differential-mode operation of the dipole antenna are respectively excited. The common-mode and differential-mode operation modes have an inherent 90° phase difference, and circular polarized radiation can be achieved simply by feeding the dual-fed antenna with equal amplitude and in-phase feed. This method solves the problem of requiring additional phase-shifting structures or devices in existing dual-fed circularly polarized antennas, simplifying the feeding structure of dual-fed circularly polarized antennas, and has excellent application prospects in mobile communications, wireless local area networks, and global positioning systems.

[0006] The present invention is achieved through the following technical solution.

[0007] According to an embodiment of the present invention, a planar double-fed circularly polarized antenna based on equal amplitude and in-phase feeding is provided. The antenna includes a dielectric substrate and a metal ground plane, a monopole antenna, and a dipole antenna printed on the upper surface of the dielectric substrate.

[0008] The monopole antenna includes a T-shaped stub, a grounded parasitic stub, and port 1 located at the end of the T-shaped stub; port 1 is connected to the T-shaped stub and the metal ground plane through the inner core and outer conductor of the coaxial line to realize the feeding of the monopole antenna and achieve common-mode operation;

[0009] The dipole antenna includes a long stub and a short stub, as well as port 2 located on the long stub; port 2 is connected to the metal at both ends of the slot in the long stub through the inner core and outer conductor of the coaxial line to feed the dipole antenna and realize differential mode operation.

[0010] By feeding the antennas at equal amplitude and in phase through ports 1 and 2, two monopole antennas and dipole antennas with orthogonal polarization and a 90° phase difference are excited respectively, thus achieving circular polarization radiation of the dual-fed antenna.

[0011] As a preferred embodiment, the dielectric substrate of the antenna, the metal ground plane printed on the surface of the dielectric substrate, the monopole antenna, and the dipole antenna are symmetrical in the y-direction.

[0012] As a preferred embodiment, the metal ground plane, monopole antenna, and dipole antenna are printed sequentially from bottom to top, and the length of the metal ground plane printed on the upper surface of the dielectric substrate is greater than the sum of the lengths of the monopole antenna and the dipole antenna.

[0013] As a preferred embodiment, the T-shaped stub of the monopole antenna includes both horizontal and vertical stubs.

[0014] As a preferred embodiment, the grounding parasitic branch has a Y-shaped opening structure, with the T-shaped branch located inside the Y-shaped opening grounding parasitic branch, and port 1 located at the end of the vertical branch of the T-shaped branch.

[0015] As a preferred embodiment, the dipole antenna includes a long stub, a short stub, and port 2. The long stub and the short stub are arranged in parallel, and port 2 is located in the middle of the long stub and is adjacent to the horizontal stub of the T-shaped stub.

[0016] As a preferred option, the sum of the length of the horizontal stub and the width of the vertical stub of the T-shaped stub is 1 / 2 of the length of the long stub in the dipole antenna, with an error not exceeding 1 / 10.

[0017] As a preferred option, the antenna dielectric substrate is made of FR4 material with a dielectric constant of 4.4.

[0018] As a preferred option, the antenna is bidirectional circularly polarized, with left-hand circularly polarized radiation in the +z direction and right-hand circularly polarized radiation in the -z direction.

[0019] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0020] This invention relates to a dual-fed circularly polarized antenna. When port 1 is fed, it can excite the common-mode operation of the monopole antenna within the antenna. When port 2 is fed, it can excite the differential-mode operation of the dipole antenna within the antenna. The common-mode and differential-mode operation of this antenna exhibit orthogonal polarization characteristics and a 90° phase difference. Therefore, when ports 1 and 2 are fed with equal amplitude and in phase, the mode strengths of the common-mode and differential-mode operation are identical, enabling circularly polarized radiation from the dual-fed antenna.

[0021] This dual-fed circularly polarized antenna, centered at 2.05 GHz, has a common relative bandwidth of no less than 24%. This common bandwidth includes the bandwidth where the reflection coefficient of port 1 and port 2 is less than -10 dB and the axial ratio is less than 3 dB. It features wide bandwidth, small size, bidirectional radiation, and a simple feeding structure, making it suitable for applications in mobile communications, wireless LANs, and GPS. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a schematic diagram of the planar double-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to the present invention.

[0024] Figure 2 The reflection coefficient curves of port 1 and port 2 of the planar double-fed circularly polarized antenna based on equal amplitude and in-phase feeding according to the present invention are shown.

[0025] Figure 3 The transmission coefficient curves of port 1 and port 2 of the planar double-fed circularly polarized antenna based on equal amplitude and in-phase feeding according to the present invention are shown.

[0026] Figure 4 This is a graph showing the circular polarization axial ratio of the planar doubly fed circularly polarized antenna based on equal amplitude and in-phase feeding according to the present invention.

[0027] Figure 5 This is a gain curve diagram of the planar double-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to the present invention.

[0028] Figure 6 The radiation efficiency curve of the planar double-fed circularly polarized antenna based on equal amplitude and in-phase feeding according to the present invention is shown.

[0029] Figure 7 This is the radiation pattern of the planar doubly fed circularly polarized antenna based on equal amplitude and in-phase feeding according to the present invention.

[0030] In the diagram: 1. Dielectric substrate; 2. Metal ground plane; 3. Monopole antenna; 31. T-shaped stub; 32. Grounded parasitic stub; 4. Dipole antenna; 41. Long stub; 42. Short stub; A. Port 1; B. Port 2. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0032] like Figure 1 The diagram shown is a schematic representation of a planar dual-fed circularly polarized antenna based on equal-amplitude and in-phase feeding, according to an embodiment of the present invention. The planar dual-fed circularly polarized antenna includes a dielectric substrate 1 and a metal ground plane 2, a monopole antenna 3, and a dipole antenna 4 printed on the upper surface of the dielectric substrate 1. The metal ground plane 2, monopole antenna 3, and dipole antenna 4 are arranged closely together from bottom to top, achieving a smaller space occupation for the antenna. The dielectric substrate 1 and the metal ground plane 2, monopole antenna 3, and dipole antenna 4 printed on the upper surface of the dielectric substrate 1 are symmetrical in the y-direction. The length of the metal ground plane 2 printed on the upper surface of the dielectric substrate 1 is greater than the sum of the lengths of the monopole antenna 3 and the dipole antenna 4, ensuring that the ground plane does not directly participate in radiation.

[0033] The monopole antenna 3 includes a T-shaped stub 31, a grounded parasitic stub 32, and a port 1A. The T-shaped stub includes horizontal and vertical stubs. The grounded parasitic stub 32 has a Y-shaped opening structure. The T-shaped stub 31 is located inside the Y-shaped opening grounded parasitic stub 32. The port 1A is located at the end of the vertical stub of the T-shaped stub 31, realizing the miniaturization design of the monopole antenna. The port 1A connects the T-shaped stub 31 and the metal ground plane 2 through the inner core and outer conductor of the coaxial cable, respectively, to feed the monopole antenna and achieve common-mode operation.

[0034] The dipole antenna 4 is a U-shaped antenna, comprising a long stub 41, a short stub 42, and port 2B. The long stub 41 and short stub 42 are arranged in parallel. Port 2B is located in the middle of the long stub 41 and is adjacent to the horizontal stub of the T-shaped stub 31, occupying only a minimal space to extend the operating bandwidth of the dipole antenna. Port 2B is connected to the metal ends of the slot in the long stub 41 within the U-shaped stub via a coaxial inner core and outer conductor, respectively, to feed the dipole antenna and achieve differential mode operation.

[0035] When ports 1A and 2B are fed with equal amplitude and in phase, the antenna can achieve circularly polarized radiation.

[0036] The dielectric substrate 1 of the antenna and the metal structures (metal ground plane 2, monopole antenna 3 and dipole antenna 4) printed on the surface of the dielectric substrate 1 are symmetrical in the y direction.

[0037] In this embodiment of the invention, the dielectric substrate has a size of 100mm × 65mm, and the antenna dielectric substrate is made of FR4 with a thickness of 1mm.

[0038] In this embodiment of the invention, when the antenna is centered at 2.05 GHz, the common relative bandwidth is not less than 24%. The common bandwidth includes the bandwidth where the reflection coefficient of port 1A and port 2B is less than -10 dB, and the bandwidth where the axial ratio is less than 3 dB.

[0039] In this embodiment of the invention, the antenna is bidirectional circularly polarized radiation, with left-hand circularly polarized radiation in the +z direction and right-hand circularly polarized radiation in the -z direction.

[0040] In this embodiment of the invention, the sum of the horizontal stub length L3 of the T-shaped stub 31 of the monopole antenna 3 and the vertical stub width W1 of the T-shaped stub is approximately 1 / 2 of the length L4 of the long stub 41 in the dipole antenna 4, with an error not exceeding 1 / 10, i.e.: (L3+W1) / L4∈[4 / 10,6 / 10].

[0041] Other structural dimensions are shown in Table 1.

[0042] Table 1

[0043] structure <![CDATA[L0]]> <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> <![CDATA[L5]]> Dimensions (mm) 100 11.5 4.6 16.5 62 37 structure <![CDATA[L6]]> <![CDATA[W0]]> <![CDATA[W1]]> <![CDATA[W2]]> <![CDATA[W3]]> Dimensions (mm) 34 65 15 2.5 3.3

[0044] Wherein: L0 is the length of the dielectric substrate 1, L1 is the vertical stub length of the grounded parasitic stub 32 of the monopole antenna 3, L2 is the tilted stub length of the grounded parasitic stub 32 of the monopole antenna 3, L3 is the vertical stub length of the T-shaped stub 31 of the monopole antenna 3, L4 is the length of the long stub 41 of the dipole antenna 4, L5 is the length of the short stub 42 of the dipole antenna 4, L6 is the vertical side length of the metal ground plate 2, W0 is the width of the dielectric substrate 1, W1 is the horizontal stub length of the T-shaped stub 31 of the monopole antenna 3, W2 is the width of the long stub 41 of the dipole antenna 4, and W3 is the width of the short stub 42 of the dipole antenna 4.

[0045] This invention achieves circular polarization of the antenna by exciting two orthogonal antenna operating modes with a 90° phase difference through two ports. When port 1 is fed, the common-mode operation of the monopole antenna in this antenna is excited; when port 2 is fed, the differential-mode operation of the dipole antenna in this antenna is excited. The common-mode and differential-mode operation modes of this antenna have orthogonal polarization characteristics and a 90° phase difference. Therefore, when antenna ports 1 and 2 are fed with equal amplitude and in phase, the mode strengths of the common-mode and differential-mode operation modes are the same, realizing circular polarization radiation of the dual-fed antenna. This dual-fed circularly polarized antenna has advantages such as wide bandwidth, small size, bidirectional radiation, and simple feeding structure, making it suitable for applications in mobile communications, wireless local area networks, and global positioning systems.

[0046] The effects of this invention can be further illustrated by simulation results:

[0047] like Figure 2 The figure shows the reflection coefficient curves of port 1 and port 2 of a planar dual-fed circularly polarized antenna based on equal amplitude and in-phase feeding according to this embodiment. The common operating frequency band of the dual ports with a reflection coefficient of less than -10dB is 1.80-2.30GHz.

[0048] like Figure 3 The figure shows the transmission coefficient curves of port 1 and port 2 of a planar dual-fed circularly polarized antenna based on equal amplitude and in-phase feeding in this embodiment. The transmission coefficient between the two ports is less than -46dB in the operating frequency band of 1.80-2.30GHz.

[0049] like Figure 4 The figure shows the circular polarization axial ratio curve of a planar dual-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to this embodiment. The 3dB axial ratio bandwidth of this circularly polarized antenna is 1.55-2.30GHz. Therefore, the common operating bandwidth of this circularly polarized antenna is 1.80-2.30GHz, the center frequency is 2.05GHz, and the relative bandwidth is 24%.

[0050] like Figure 5 The figure shown is a gain curve of a planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to this embodiment. The gain of this circularly polarized antenna is greater than 3dB in its operating frequency band.

[0051] like Figure 6 The figure shown is a radiation efficiency curve of a planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to this embodiment. The radiation efficiency of this circularly polarized antenna is greater than 95% within its operating frequency band.

[0052] like Figure 7 The image shows the radiation pattern of a planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding, according to this embodiment. This circularly polarized antenna possesses bidirectional radiation capability. Figure 7 In the images, (a) and (b) show that the 3dB beamwidth is greater than 60°.

[0053] The foregoing has provided a detailed description of a planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding, and has elucidated and implemented the principles and methods of the present invention using detailed structural design parameters. The descriptions of the embodiments above are merely for the purpose of aiding understanding the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0054] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding, characterized in that, The antenna includes a dielectric substrate and a metal ground plane, a monopole antenna, and a dipole antenna printed on the surface of the dielectric substrate. The metal ground plane, monopole antenna, and dipole antenna are printed sequentially from bottom to top, and the dielectric substrate of the antenna and the metal ground plane, monopole antenna, and dipole antenna printed on the upper surface of the dielectric substrate are symmetrical in the y direction. The monopole antenna includes a T-shaped stub, a grounded parasitic stub, and a port 1 located at the end of the T-shaped stub; the T-shaped stub of the monopole antenna includes a horizontal stub and a vertical stub; the grounded parasitic stub has a Y-shaped opening structure, the T-shaped stub is located inside the Y-shaped opening grounded parasitic stub, and the port 1 is located at the end of the vertical stub of the T-shaped stub. Port 1 is connected to the T-shaped stub and the metal ground plane via the inner core and outer conductor of the coaxial line, respectively, to feed the monopole antenna and achieve common-mode operation. The dipole antenna includes a long stub and a short stub, and a port 2 located on the long stub; the long stub and the short stub are arranged in parallel, and the port 2 is located in the middle of the long stub and is adjacent to the horizontal stub of the T-shaped stub. Port 2 connects to the metal at both ends of the slot in the long stub via the inner core and outer conductor of the coaxial line to feed the dipole antenna and achieve differential mode operation. By feeding ports 1 and 2 with equal amplitude and in phase, two monopole antennas and dipole antennas with orthogonal polarization and a 90° phase difference are excited respectively, thus realizing the circular polarization radiation of the dual-fed antenna.

2. The planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to claim 1, characterized in that, The length of the metal ground plane printed on the surface of the dielectric substrate is greater than the sum of the lengths of the monopole antenna and the dipole antenna.

3. The planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to claim 1, characterized in that, The sum of the length of the horizontal stub and the width of the vertical stub of the T-shaped stub is 1 / 2 of the length of the long stub in the dipole antenna, with an error not exceeding 1 / 10.

4. The planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to claim 1, characterized in that, The antenna dielectric substrate is made of FR4 material with a dielectric constant of 4.

4.

5. The planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to claim 1, characterized in that, The antenna is bidirectional circularly polarized, with left-hand circularly polarized radiation in the +z direction and right-hand circularly polarized radiation in the -z direction.

6. The planar doubly-fed circularly polarized antenna based on equal-amplitude and in-phase feeding according to any one of claims 1-5, characterized in that, When the antenna is centered at 2.05 GHz, the common relative bandwidth is not less than 24%; the common bandwidth includes the bandwidth of port 1 and port 2 with reflection coefficients less than -10 dB and axial ratios less than 3 dB.

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