A miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength

Abstract

This invention relates to the field of antenna technology, and particularly to a miniaturized circularly polarized antenna with a wide axial ratio and wide beamwidth. The antenna includes a dielectric substrate, a circular radiating patch unit, metal shorting posts, a coaxial differential feed structure, and a metal ground plane. The circular radiating patch unit consists of a pair of orthogonal fan-shaped cross-printed dipoles. A slot structure is added in the middle along the X-axis to divide the radiator into left and right parts, and three metal shorting posts are added to the end of each fan-shaped cross-printed dipole structure. The feed structure is a differential-feed coaxial cable, with its inner and outer conductors contacting the left and right halves of the circular radiating patch unit, respectively. Simultaneously, due to the slight difference in curvature between the two orthogonal fan-shaped printed dipoles, a phase difference is formed between the pair of orthogonal modes of the circular radiating patch unit, ultimately achieving circularly polarized radiation of the antenna. A metal short-circuit post is applied to the electric field zero of a conventional printed dipole, forming a new half-mode operating mode at low frequencies. Simultaneously, the slot structure improves the impedance characteristics of the half-mode, enabling antenna miniaturization. Due to the radiation contribution of the metal short-circuit post in the horizontal direction, the axial ratio beamwidth of this circularly polarized antenna is significantly extended. This application exhibits excellent forward radiation characteristics, along with miniaturization, a wide axial ratio beamwidth, simple structure, low cost, and ease of fabrication.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength. Background Technology

[0002] Low-Earth orbit (LEO) satellite networking technology plays an increasingly important role in the Internet of Things (IoT) due to its ability to fill signal gaps in terrestrial IoT networks, significantly enhancing daily communication experiences for both military and civilian use. LEO satellites move rapidly in their orbits, requiring satellite antennas to employ circularly polarized radiation to combat interference and possess wide axial ratio beamwidths to achieve extensive signal coverage in order to ensure stable transmission of high-quality communication signals. Furthermore, LEO satellites are typically composed of small satellites, meaning that the design space for LEO satellite antennas is limited, necessitating miniaturization. Therefore, research on miniaturized circularly polarized antennas with wide axial ratio beamwidths is essential for both academia and industry. Summary of the Invention

[0003] This invention discloses a miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength, the antenna comprising: Dielectric substrate; A circular radiating patch unit is disposed on the upper surface of the dielectric substrate; A metal floor is disposed on or below the lower surface of the dielectric substrate; A coaxial feeding structure is used for differential feeding of the circular radiating patch unit; Multiple metal short-circuit posts are electrically connected between the circular radiating patch unit and the metal ground plate; The circular radiating patch unit is composed of a pair of orthogonally placed fan-shaped cross-printed dipoles, including a first printed dipole along a first direction Phi=+45° and a second printed dipole along a second direction Phi=-45°; the circular radiating patch unit has a slot structure that penetrates the radiator along one of its diameter directions, dividing the circular radiating patch unit into a left half and a right half. The first printed dipole consists of a first driving unit and a pair of fan-shaped first NFRP radiating units. The first driving unit is shaped like an Egyptian axe and includes a central pad and a fan-shaped end. The first NFRP radiating units are located at both ends of the axe blade of the Egyptian axe-shaped first driving unit. The gap width between the first driving unit and the first NFRP radiating units is g2, and the angle formed by the end of the first driving unit and the fan-shaped first NFRP radiating units is θ2. The second printed dipole consists of a second driving unit and a pair of fan-shaped second NFRP radiating units. The second driving unit is shaped like an Egyptian axe. The first driving unit includes a central pad and a fan-shaped end. The second NFRP radiating units are located at both ends of the axe blade of the Egyptian axe-shaped second driving unit. The gap width between the second driving unit and the second NFRP radiating units is g2, and the angle formed by the end of the second driving unit and the fan-shaped first NFRP radiating units is θ3. The parameter difference between θ3 and θ2 provides a 90° phase difference for the circularly polarized radiation of the antenna.

[0004] Furthermore, the sector angle θ2 of the first printed dipole is 80°, and the sector angle θ3 of the second printed dipole is 89.8°. Furthermore, the gap width g2 is 0.1 mm.

[0005] Furthermore, the coaxial feed structure is a 50Ω coaxial feed line, whose inner conductor and outer conductor are directly connected to the left and right halves of the circular radiating patch unit, respectively; the outer conductor of the coaxial feed structure is not connected to the metal ground plane.

[0006] Furthermore, the radius R4 of the circular radiating patch unit is 11 mm; the width g1 of the groove structure is 0.25 mm.

[0007] Furthermore, both the first NFRP radiating unit and the second NFRP radiating unit are connected to three metal short-circuit posts; the distance R5 between the metal short-circuit post and the center of the circular radiating patch unit is 10.5mm, the included angle θ5 between adjacent metal short-circuit posts is 10°, and the diameter d1 of the metal short-circuit post is 0.5mm.

[0008] Furthermore, the dielectric substrate is a cylinder made of Rogers RO5880 material with a relative permittivity of 2.2, a loss tangent of 0.0009, a thickness h1 of 4 mm, and a radius of 26 mm.

[0009] Furthermore, the distance between the inner and outer conductors of the coaxial feed structure and the center of the circular radiating patch unit is 0.8 mm, and the diameter of its connecting probe is 0.5 mm.

[0010] Furthermore, the metal floor is printed on the lower surface of the dielectric substrate, and its diameter is the same as that of the dielectric substrate, both being 52 mm.

[0011] Furthermore, the first printed dipole and the second printed dipole are rotationally symmetrical about the center of the circle by 180°, and are axially symmetrical about the direction Phi=±45°.

[0012] Because of the adoption of the above technical solution, the present invention has the following advantages: 1. Based on the traditional printed dipole, this application innovatively introduces a metal short-circuit post structure, which enables a new half-mode working mode at low frequency points, providing a premise for the miniaturization and low profile of the traditional printed dipole.

[0013] 2. This application effectively improves the impedance characteristics of the half-mode operation mode by dividing the printed dipole into a driving unit and a pair of NFRP radiating units in the form of an introduced slot structure, so as to achieve good matching.

[0014] 3. This application achieves good circular polarization radiation by placing a pair of printed dipoles orthogonally while ensuring a slight difference in their curvature; due to the contribution of the metal short-circuit post to the radiation energy of the pattern horizontal plane, the circular polarization antenna obtains an extremely wide axial ratio beam.

[0015] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0016] The accompanying drawings of this invention are described below.

[0017] Figure 1 This is a schematic diagram of the antenna structure.

[0018] Figure 2 This is a top view of a circular radial patch unit.

[0019] Figure 3 This is a diagram showing the dimensions of the antenna.

[0020] Figure 4 Front view of the antenna Figure 5 In this embodiment of the invention, the antenna's reflection coefficient curve (|S11| curve) and overall efficiency curve (OE curve) are shown. Figure 6 This is a schematic diagram of the achievable gain curve and axial ratio curve of the antenna in an embodiment of the present invention.

[0021] Figure 7 This is the axial ratio radiation pattern of the antenna in the xz and yz planes at a frequency of 3.165 GHz in an embodiment of the present invention.

[0022] Figure 8 This is a right-hand circularly polarized radiation pattern of the antenna in the xz and yz planes at a frequency of 3.165 GHz in an embodiment of the present invention.

[0023] In the figure: 1-Dielectric substrate; 2-Circular radiating patch unit; 3-Coaxial feed structure; 4-Metal short-circuit post; 5-Metal ground plane; 201-First printed dipole, 202-Second printed dipole, 201_1-Drive unit, 201_2-A pair of NFRP radiating units. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the embodiments of the present invention, it should be noted that unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0026] A miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength, see [link / reference]. Figures 1 to 4 The antenna includes: Dielectric substrate 1; A circular radiating patch unit 2 is disposed on the upper surface of the dielectric substrate 1; Metal floor 5 is disposed on or below the lower surface of the dielectric substrate 1; The coaxial feeding structure 3 is used to differentially feed the circular radiating patch unit 2; Multiple metal short-circuit posts 4 are electrically connected between the circular radiating patch unit 2 and the metal floor 5; The circular radiating patch unit 2 is composed of a pair of orthogonally placed fan-shaped cross-printed dipoles, including a first printed dipole 201 along a first direction Phi=+45° and a second printed dipole 202 along a second direction Phi=-45°; the circular radiating patch unit 2 has a slot structure that penetrates the radiator along one of its diameter directions, dividing the circular radiating patch unit 2 into a left half and a right half; The first printed dipole 201 consists of a first driving unit 201_1 and a pair of fan-shaped first NFRP radiating units 201_2. The first driving unit 201_1 is shaped like an Egyptian axe and includes a central pad and a fan-shaped end. The first NFRP radiating units 201_2 are located at both ends of the axe blade of the Egyptian axe-shaped first driving unit 201_1. The gap width between the first driving unit 201_1 and the first NFRP radiating units 201_2 is g2, and the angle formed by the end of the first driving unit 201_1 and the fan-shaped first NFRP radiating units 201_2 is θ2. The second printed dipole 202 consists of a second driving unit and a pair of fan-shaped second NFRP radiating units. The second driving unit is shaped like an Egyptian axe and includes a central pad and a fan-shaped end. The second NFRP radiating units are located at both ends of the axe blade of the Egyptian axe-shaped second driving unit. The gap width between the second driving unit and the second NFRP radiating units is g2, and the angle formed by the end of the second driving unit and the fan-shaped first NFRP radiating units is θ3. Both the first driving unit and the second driving unit include a central pad and a fan-shaped end. The parameter difference between θ3 and θ2 provides a 90° phase difference for the circularly polarized radiation of the antenna.

[0027] It should be noted that the circular radiating patch unit consists of a pair of orthogonal sector-shaped cross-printed dipoles. A slot structure is loaded in the middle along the X-axis, dividing the radiator into left and right parts. Each sector-shaped cross-printed dipole structure has three metal short-circuit posts at its end. The feeding structure is a differential-feed coaxial cable, with its inner and outer conductors contacting the left and right halves of the circular radiating patch unit, respectively. Due to the slight difference in curvature between the two orthogonal sector-shaped printed dipoles, a phase difference is formed between the pair of orthogonal modes in the circular radiating patch unit, ultimately achieving circular polarization radiation of the antenna. The metal short-circuit posts are loaded at the electric field zero point of the traditional printed dipole, forming a new half-mode operating mode at low frequencies. Simultaneously, the slot structure improves the impedance characteristics of the half-mode, enabling antenna miniaturization. Due to the contribution of the metal short-circuit posts to radiation in the horizontal direction, the axial ratio and bandwidth of this circularly polarized antenna are also significantly extended.

[0028] In this embodiment, the loading of the metal short-circuit post at the low frequency of a conventional cross-printed dipole generates a new half-mode operating mode, enabling miniaturization of the conventional cross-printed dipole antenna. Due to the contribution of the metal short-circuit post to the radiated energy of the pattern in the horizontal plane, the axial ratio beam of the antenna is broadened.

[0029] In one embodiment of the present invention, the dielectric substrate material is Rogers RO5880, with a relative permittivity of 2.2 and a loss tangent of 0.0009. It is a cylinder with a thickness h1 of 4 mm and a diameter of 52 mm.

[0030] In one embodiment of the present invention, in the circular radiating patch unit, the outer diameter R4 of the end of the cross-printed dipole fan-shaped NFRP radiating unit is 11 mm, and the angles θ2 and θ3 in the +45° and -45° directions are 80° and 89.8°, respectively.

[0031] As an embodiment of the present invention, the center pad radius R1 of the driving unit is 1.6 mm, the gap width g1 in the middle is 0.25 mm, the inner radius R2 of the end of the driving unit is 3.1 mm, the outer radius R3 is 3.9 mm, and the angle θ1 between the connecting pad and the end fan-shaped strip is 15°.

[0032] In one embodiment of the present invention, the gap width g2 between the driving unit and the NFRP radiating unit is 0.1 mm.

[0033] In one embodiment of the present invention, the distance R5 between the metal short-circuit post and the center of the circle is 10.5 mm, the angle θ5 between the metal short-circuit posts is 10°, and the diameter d1 of the metal short-circuit post is 0.5 mm.

[0034] In one embodiment of the present invention, the distance between the inner and outer conductors of the coaxial feeding structure and the center is 0.8 mm, and the diameter of its connecting probe is 0.5 mm.

[0035] In one embodiment of the present invention, the metal floor is attached to the lower surface of the substrate, and its diameter is the same as that of the substrate, both being 52 mm.

[0036] After completing the initial design described above, simulation analysis was performed using the high-frequency electromagnetic simulation software HFSS. The optimal dimensions of each parameter after simulation optimization are shown in the table below: Parameters Dimensions (mm) [R1] 1.6 [R2] 3.1 [R3] 3.9 [R4] 11 [R5] 10.5 [theta1] 15° [theta2] 80° [theta]3 89.8° [theta]4 5.1° [theta]5 10° [cl] 0.25 [g2] 0.1 d1 0.5 [CDATA[h2]]> 4 4 Based on the above parameters, the reflection coefficient characteristics of the designed dual-frequency antenna array were simulated and tested using HFSS. The analysis results are as follows: Figure 5 The port reflection coefficient |S of the miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength according to the present invention. 11 Simulation curves and overall efficiency (OE) curves. Simulation results show that the antenna's impedance bandwidth is 3.10-3.27 GHz, corresponding to a fractional bandwidth of 5.34%. The overall efficiency reaches 93.4%. Figure 6The simulation results show that the axial ratio bandwidth of the miniaturized circularly polarized antenna with a wide axial ratio bandwidth of the present invention covers 3.140-3.191 GHz, corresponding to a fractional bandwidth of 1.64%. The maximum achievable gain within the axial ratio bandwidth is 5.24 dBi.

[0037] Figure 7 The simulation results show that the axial ratio radiation pattern characteristics of the miniaturized circularly polarized antenna with wide axial ratio wavelength of the present invention are as follows: in the xz and yz planes at 3.165 GHz, the axial ratio wavelengths of the antenna in the xz and yz planes are 202° and 208°, respectively, which can cover the entire upper hemisphere and exhibit extremely wide axial ratio wavelengths.

[0038] Figure 8 The radiation pattern characteristics of the miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength at 3.165 GHz in the xz and yz planes of this invention demonstrate that the invention has good forward radiation characteristics. The miniaturized circularly polarized antenna with a wide axial ratio and wavelength of this application can reduce the size of conventional cross-printed dipole antennas in a simple and effective way, while maintaining a low profile height and having a wide axial ratio and wavelength and forward radiation characteristics.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength, characterized in that, The antenna includes: Dielectric substrate (1); A circular radiating patch unit (2) is disposed on the upper surface of the dielectric substrate (1); A metal floor (5) is disposed on or below the lower surface of the dielectric substrate (1); A coaxial feeding structure (3) is used to differentially feed the circular radiating patch unit (2); Multiple metal short-circuit posts (4) are electrically connected between the circular radiating patch unit (2) and the metal floor (5); The circular radiating patch unit (2) is composed of a pair of orthogonally placed fan-shaped cross-printed dipoles, including a first printed dipole (201) along the first direction Phi=+45° and a second printed dipole (202) along the second direction Phi=-45°; the circular radiating patch unit (2) has a slot structure that penetrates the radiator along one of its diameter directions, dividing the circular radiating patch unit (2) into a left half and a right half; The first printed dipole (201) consists of a first driving unit (201_1) and a pair of fan-shaped first NFRP radiating units (201_2). The first driving unit (201_1) is shaped like an Egyptian axe and includes a central pad and a fan-shaped end. The first NFRP radiating units (201_2) are located at both ends of the axe blade of the Egyptian axe-shaped first driving unit (201_1). The gap width between the first driving unit (201_1) and the first NFRP radiating units (201_2) is g2, and the angle formed by the end of the first driving unit (201_1) and the fan-shaped first NFRP radiating units (201_2) is θ2. The second printed dipole (202) consists of a second driving unit and a pair of fan-shaped second NFRP radiating units. The second driving unit is in the shape of an Egyptian axe and includes a central pad and a fan-shaped end. The second NFRP radiating units are located at both ends of the axe blade of the Egyptian axe-shaped second driving unit. The gap width between the second driving unit and the second NFRP radiating units is g2, and the angle formed by the end of the second driving unit and the fan-shaped first NFRP radiating units is θ3. Both the first driving unit and the second driving unit include a central pad and a fan-shaped end. The parameter difference between θ3 and θ2 provides a 90° phase difference for the circularly polarized radiation of the antenna.

2. The miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength as described in claim 1, characterized in that, The sector angle θ2 of the first printed dipole (201) is 80°, and the sector angle θ3 of the second printed dipole (202) is 89.8°.

3. The miniaturized circularly polarized antenna with a wide axis ratio and wide wavelength as described in claim 1, characterized in that, The gap width g2 is 0.1mm.

4. The miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength as described in claim 1, characterized in that, The coaxial power supply structure (3) is a 50Ω coaxial power supply line, and its inner conductor and outer conductor are directly connected to the left half and right half of the circular radiating patch unit (2), respectively; the outer conductor of the coaxial power supply structure (3) is not connected to the metal floor (5).

5. The miniaturized circularly polarized antenna with a wide axis ratio and wide wavelength as described in claim 1, characterized in that, The radius R4 of the circular radiating patch unit (2) is 11 mm; the width g1 of the groove structure is 0.25 mm.

6. The miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength as described in claim 1, characterized in that, The first NFRP radiating unit and the second NFRP radiating unit are each connected to three metal short-circuit posts (4); the distance R5 between the metal short-circuit post (4) and the center of the circular radiating patch unit is 10.5 mm, the included angle θ5 between adjacent metal short-circuit posts is 10°, and the diameter d1 of the metal short-circuit post (4) is 0.5 mm.

7. The miniaturized circularly polarized antenna with a wide axis ratio and wide wavelength as described in claim 1, characterized in that, The dielectric substrate (1) is a cylinder made of Rogers RO5880 with a relative permittivity of 2.2, a loss tangent of 0.0009, a thickness h1 of 4 mm, and a radius of 26 mm.

8. The miniaturized circularly polarized antenna with a wide axis ratio and wide wavelength as described in claim 1, characterized in that, The distance between the inner and outer conductors of the coaxial feed structure (3) and the center of the circular radiating patch unit (2) is 0.8 mm, and the diameter of its connecting probe is 0.5 mm.

9. The miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength as described in claim 1, characterized in that, The metal floor (5) is printed on the lower surface of the dielectric substrate (1), and its diameter is the same as that of the dielectric substrate (1), both being 52 mm.

10. The miniaturized circularly polarized antenna with a wide axial ratio and wide wavelength as described in claim 1, characterized in that, The first printed dipole (201) and the second printed dipole (202) are rotationally symmetrical about the center of the circle by 180°, and are axially symmetrical about the direction of Phi=±45°.

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