Planar end-fire dual-frequency circularly polarized antenna with small frequency ratio

Abstract

The invention relates to a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, which comprises a first magnetic dipole unit used for providing a vertical polarization component, and the first magnetic dipole unit comprises a medium, a first patch assembly, a first short circuit assembly and a feed end, the first patch assembly and the first short circuit assembly form a first cavity; the feed end is arranged on the first patch assembly; the second electric dipole unit comprises a first folding structure and a second folding structure, the second folding structure is a reverse folding structure of the first folding structure, and the second folding structure and the first folding structure form a complementary structure at the tail end. According to the invention, the structure is simple, the requirements of circular polarization phases of two frequency bands can be met at the same time, and the design complexity and the processing and manufacturing cost are greatly reduced; the complementary structure of the folded electric dipole tail end structure and the reverse extension branch knot can realize a small frequency ratio of about 1.3, and has the advantages of high gain and wide impedance bandwidth at high frequency.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and in particular to a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio. Background Art

[0002] Dual-band circularly polarized antennas are capable of circularly polarized radiation in two different frequency bands. These antennas can cover a wider range of frequency bands, effectively improving the efficiency and quality of communication systems. Therefore, they are widely used in satellite navigation, wireless communications, radar systems, and other fields. Traditional dual-band circularly polarized antennas use patch-type implementations, and their primary radiation direction is broadside, making them unsuitable for systems requiring end-fire circularly polarized beams.

[0003] Existing dual-band end-fire circular polarization technologies include the following. The first document "A Planar End-Fire Dual-Band Circularly Polarized Antenna" (DOI: 10.26914 / c.cnkihy.2023.094490) discloses a method based on the combination of electric dipoles and loop antennas. The horizontal polarization components are provided by the loop unit and the electric dipole unit, respectively, and can cover 2.4 GHz and 5.0 GHz; the second document "Novel Dual-Band Circularly Polarized Planar Endfire AntennaWith Enhanced Front-to-Back Ratios" (DOI: 10.1109 / TAP.2021.3111160) proposes a dual-band end-fire circularly polarized antenna based on high-order modes, introducing two pairs of printed dipoles operating at 2.4 GHz and 5.0 GHz, respectively, to provide the horizontal component required for circular polarization. The third paper, "Conceptual design of a dual-band circularly polarized antenna" (DOI: 10.1109 / ICUWB.2016.7790493), proposes a method that incorporates square rings to achieve coverage of both the 6.0 GHz and 9.5 GHz bands. However, to excite the square ring radiating elements, the delay line length reaches three-quarters of a wavelength, increasing the complexity of the structural design and energy loss, resulting in a gain of less than 6 dB at high frequencies.

[0004] However, the existing technologies are deficient in that the frequency ratio of the method based on combining an electric dipole and a loop antenna in Document 1 exceeds 2.0. Furthermore, due to the inherent omnidirectional radiation characteristics of the loop antenna, its back radiation is large, resulting in energy waste and low gain in the end-fire direction. In Document 2, to achieve a 90-degree phase difference, the curved delay line structure significantly increases the design complexity and manufacturing cost. Furthermore, an additional narrow slot structure is required to adjust its high-frequency operating mode, making it difficult to achieve a small frequency ratio. The square loop-based implementation method in Document 3 uses a delay line length of three-quarters of a wavelength, which not only increases the complexity of the structural design but also easily causes energy loss, resulting in a gain of less than 6dB at high frequencies. Furthermore, its impedance matching is poor and the operating bandwidth is narrow. Furthermore, the frequency ratio of this solution exceeds 1.5.

[0005] Therefore, there is an urgent need to design a planar end-fire dual-frequency circularly polarized antenna with a simple structure and the ability to achieve a small frequency ratio. Summary of the Invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, which utilizes a single folded electric dipole structure to simultaneously provide low-frequency and high-frequency horizontal polarization components, thereby reducing the waste of back-radiated energy and improving the gain in the end-fire direction; a small frequency ratio of about 1.3 can be achieved, and it has the advantages of high gain and wide impedance bandwidth at high frequencies.

[0007] In order to solve the above technical problems, the present invention provides a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, comprising: A first magnetic dipole unit, configured to provide a dual-frequency vertically polarized component, comprising a dielectric, a first patch component, a first short-circuit component, and a feeding end, wherein the first patch component and the first short-circuit component form a first cavity, the dielectric being disposed within the first cavity, and an opening being formed at one end of the first cavity to radiate energy in a first direction; the feeding end being disposed in the first patch component; a second electric dipole unit, configured to provide a dual-frequency horizontal polarization component, the second electric dipole unit comprising a first folded structure and a second folded structure, the second folded structure being a reverse folded structure of the first folded structure and forming a complementary structure with the first folded structure at an end; A delay line unit, wherein the first magnetic dipole unit and the second electric dipole unit are connected through the delay line unit to provide the orthogonal phase difference required for circular polarization; the delay line unit includes a first strip line and a second strip line parallel to each other along the first direction, one end of the first strip line is connected to the first patch component, and the other end is connected to the second folding structure; one end of the second strip line is connected to the first patch component, and the other end is connected to the first folding structure.

[0008] In one embodiment of the present invention, the first patch assembly includes a first patch and a second patch, the medium has a first surface and a second surface opposite to each other along the thickness direction, the first patch is arranged on the first surface, the second patch is arranged on the second surface, and the feeding end is arranged on the second surface.

[0009] In one embodiment of the present invention, the first short-circuit component includes a first section, a second section, and a third section sequentially arranged around the medium, wherein two ends of the second section are connected to the first section and the third section respectively.

[0010] In one embodiment of the present invention, the first folding structure includes a first radiation component and a second short-circuit component, the first radiation component includes a first upper arm and a first lower arm arranged in parallel, the second short-circuit component includes a first strip, and the ends of the first strip are respectively connected to the first upper arm and the first lower arm to form a first "U-shaped" structure.

[0011] In one embodiment of the present invention, the second folding structure includes a second radiating component and a third short-circuit component, the second radiating component includes a second upper arm and a second lower arm arranged in parallel, the third short-circuit component includes a second strip, and the ends of the second strip are respectively connected to the second upper arm and the second lower arm to form a second "U-shaped" structure.

[0012] In one embodiment of the present invention, the end of the first upper arm close to the second upper arm is the first end, the end of the second upper arm close to the first upper arm is the second end, and the edge shape of the first end and the edge shape of the second end are complementary; the first end has a first protrusion, and the second end has a first reverse-extending branch node matching the first protrusion, and the first reverse-extending branch node is a first concave portion formed inwardly along the second end.

[0013] In one embodiment of the present invention, the end of the first lower arm close to the second lower arm is the third end, the end of the second lower arm close to the first lower arm is the fourth end, and the edge shape of the third end is complementary to the edge shape of the fourth end; the fourth end has a second inner recess, and the third end has a second reverse extension branch node matching the second inner recess, and the second reverse extension branch node is a second protrusion formed along the outward bulge of the third end.

[0014] In one embodiment of the present invention, a feeding coaxial cable is further included. The feeding coaxial cable is arranged at the feeding end and extends along the Z direction.

[0015] In one embodiment of the present invention, the dielectric constant of the medium is 1-20.

[0016] In one embodiment of the present invention, the length of the first magnetic dipole is 85-95 mm, the width is 42-47 mm, and the height is 6.5-8 mm; the length of the first strip line and the second strip line is 20-26 mm.

[0017] The above technical solution of the present invention has the following advantages over the prior art: The present invention discloses a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, comprising a first magnetic dipole unit, a second electric dipole unit, and a delay line unit. The first magnetic dipole unit and the second electric dipole unit are connected via the delay line unit to provide the orthogonal phase difference required for circular polarization. The first magnetic dipole unit is configured to provide a vertical polarization component, and the second electric dipole unit is configured to provide a horizontal polarization component. The first magnetic dipole unit comprises a dielectric, a first patch assembly, a first short-circuit assembly, and a feed end. The first short-circuit assembly is configured to connect to the first patch assembly, and the feed end is disposed on the first patch assembly. The second electric dipole unit comprises a first folded structure and a second folded structure, the first and second folded structures being disposed relative to each other and forming a complementary structure. The present invention utilizes a single folded electric dipole structure to simultaneously provide low-frequency and high-frequency horizontally polarized components, thereby reducing the waste of back-radiated energy while increasing the gain in the end-fire direction. The present invention has a simple structure, and the first magnetic dipole unit and the second electric dipole unit adopt a structural design of a shared delay line unit, which can simultaneously meet the circular polarization phase requirements of two frequency bands, significantly reducing the complexity of the design and the processing and manufacturing costs. In addition, the existing technology can generally only achieve a frequency ratio of about 2.0. The complementary structure of the folded electric dipole end structure and the reverse extension branch of the present invention can achieve a small frequency ratio of about 1.3, and has the advantages of high gain and wide impedance bandwidth at high frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 It is a schematic diagram of the overall structure of a planar end-fire dual-frequency circularly polarized antenna according to a preferred embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the parameters of the planar end-fire dual-frequency circularly polarized antenna according to the preferred embodiment of the present invention.

[0021] Figure 3 yes Figure 1 Schematic diagram of the structure in which the positions of the first folding structure 6 and the second folding structure 7 are interchanged to form right-handed circular polarization.

[0022] Figure 4 yes Figure 1 Top view of .

[0023] Figure 5 yes Figure 1 Bottom view of .

[0024] Figure 6 yes Figure 1 main view.

[0025] Figure 7 yes Figure 1 side view.

[0026] Figure 8 yes Figure 1 Magnified view of the top incision A.

[0027] Figure 9 yes Figure 1 Magnified view of the bottom cutout B.

[0028] Figure 10 It is a simulation diagram of antenna S11 according to a preferred embodiment of the present invention.

[0029] Figure 11 It is a simulation diagram of the antenna axial ratio of a preferred embodiment of the present invention.

[0030] Figure 12 It is a simulation diagram of the antenna gain characteristic curve of the preferred embodiment of the present invention.

[0031] Figure 13 It is the YOZ plane radiation pattern of the low frequency 2.18 GHz of the preferred embodiment of the present invention.

[0032] Figure 14 This is the YOZ plane radiation pattern of the high frequency 2.80 GHz of the preferred embodiment of the present invention.

[0033] Figure 15 This is the XOY plane radiation pattern of the low frequency 2.18 GHz of the preferred embodiment of the present invention.

[0034] Figure 16 This is the XOY plane radiation pattern of the high frequency 2.80 GHz of the preferred embodiment of the present invention.

[0035] Figure 17 It is a structural schematic diagram of model 1 of the preferred embodiment of the present invention.

[0036] Figure 18 It is a structural schematic diagram of Model 2 of the preferred embodiment of the present invention.

[0037] Figure 19 It is a structural schematic diagram of model three of the preferred embodiment of the present invention.

[0038] Figure 20 This is the evolution process of the approximate complementary structure on the surface of the second electric dipole unit of model three.

[0039] Figure 21 This is the evolution process of the approximate complementary structure on the lower surface of the second electric dipole unit in model three.

[0040] Figure 22 This is a comparison chart of the reflection coefficients of model one, model two, and model three.

[0041] Figure 23 This is a comparison chart of the axial ratios of Model 1, Model 2, and Model 3.

[0042] Figure 24 This is a comparison chart of the total gains of Model 1, Model 2, and Model 3.

[0043] Explanation of the figure marks in the specification: 1. Medium; 2. First patch component; 21. First patch; 22. Second patch; 3. First short-circuit component; 31. First section; 32. Second section; 33. Third section; 4. Feeding end; 6. First folding structure; 61. First upper arm; 62. First lower arm; 63. First strip; 7. Second folding structure; 71. Second upper arm; 72. Second lower arm; 73. Second strip; 8. Delay line unit; 81. First strip line; 82. Second strip line. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0045] Reference Figures 1 to 24As shown, the present invention discloses a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, comprising a first magnetic dipole unit, wherein the first magnetic dipole unit is used to provide a vertical polarization component.

[0046] Specifically, the first magnetic dipole unit includes a medium 1, a first patch component 2, a first short-circuit component 3 and a feeding end 4. The first patch component 2 and the first short-circuit component 3 form a first cavity. The medium 1 is arranged in the first cavity, and the medium 1 matches the first cavity. An opening is formed at one end of the first cavity, and the first magnetic dipole unit radiates energy in a first direction through the opening. The feeding end 4 is arranged on the first patch component, and the feeding end 4 is used to input an electrical signal to generate an excitation signal.

[0047] In this embodiment, the center position of the energy radiation of the first magnetic dipole unit is defined as the origin of the rectangular coordinate system, the first direction is defined as the +Y direction, so the end-fire direction is the +Y direction, and the feeding end 4 is located on the straight line where the Y axis is located.

[0048] The planar end-fire dual-frequency circularly polarized antenna also includes a second electric dipole unit, which is used to provide a horizontal polarization component. The second electric dipole unit includes a first folding structure 6 and a second folding structure 7. The first folding structure 6 and the second folding structure 7 are arranged relative to each other along the direction of the Y axis. The first folding structure 6 extends along the +X direction, and the second folding structure 7 extends along the -X direction. In addition, the first folding structure 6 and the second folding structure 7 form complementary reverse folding structures.

[0049] The planar end-fire dual-frequency circularly polarized antenna further includes a delay line unit 8 , through which the first magnetic dipole unit and the second electric dipole unit are connected to provide the orthogonal phase difference required for circular polarization.

[0050] Specifically, the delay line unit 8 includes a first strip line 81 and a second strip line 82 parallel to each other along the first direction. The first strip line 81 and the second strip line 82 are of equal length. One end of the first strip line 81 is connected to the first patch component 2, and the other end is connected to the second folded structure 7. One end of the second strip line 82 is connected to the first patch component 2, and the other end is connected to the first folded structure 6. The length L1 of the first strip line 81 is set to be approximately one-quarter of the wavelength of the high-frequency resonance point.

[0051] To achieve dual-frequency circular polarization with a small frequency ratio, the present invention's planar end-fire dual-frequency circularly polarized antenna utilizes a shared delay line unit design. First, the length L1 of the first strip line 81 in the delay line unit is set to a quarter wavelength relative to the high-frequency resonance point of 2.80 GHz. Next, to compensate for the phase difference at the low frequency of 2.18 GHz, the present invention also provides a folded second electric dipole unit. This second electric dipole unit includes a first folded structure 6 and a second folded structure 7 arranged opposite each other along the first direction. The second folded structure 7 is a reverse folded structure of the first folded structure 6 and forms a complementary structure with the first folded structure 6 at its end.

[0052] The method for determining left-handed circular polarization of the present invention is as follows: an electrical signal is input from the feed end 4, enters the first strip line 81 through the first patch component 2, reaches the second folded structure 7, flows through the first folded structure 6 through the second folded structure 7, and returns to the first patch component 2 through the second strip line 82, forming left-handed circular polarization in the first direction (i.e., +Y direction). In addition, the positions of the first folded structure 6 and the second folded structure 7 can be interchanged. After the interchange, the direction of circular polarization changes, thereby forming right-handed circular polarization. Figure 3 As shown, Figure 3 Schematic diagram of the structure for right-handed circular polarization.

[0053] From this, it can be seen that the present invention is to protect a planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, which is provided with a first magnetic dipole unit, a second electric dipole unit and a delay line unit. The first magnetic dipole unit and the second electric dipole unit are connected through the delay line unit to provide the orthogonal phase difference required for circular polarization. Among them, the first magnetic dipole unit is used to provide a vertical polarization component, and the second electric dipole unit is used to provide a horizontal polarization component. The first magnetic dipole unit includes a dielectric, a first patch assembly, a first short-circuit assembly and a feeding end. The first short-circuit assembly is used to connect the first patch assembly, and the feeding end is arranged on the first patch assembly. The second electric dipole unit includes a first folding structure and a second folding structure. The first folding structure and the second folding structure are arranged relative to each other and form a complementary structure. The present invention utilizes a single folded electric dipole structure to simultaneously provide low-frequency and high-frequency horizontally polarized components, thereby reducing the waste of back-radiated energy while increasing the gain in the end-fire direction. The first magnetic dipole unit and the second electric dipole unit of the present invention adopt a structural design of a shared delay line unit, which can simultaneously meet the circular polarization phase requirements of two frequency bands, significantly reducing the complexity of the design and the processing and manufacturing costs. In addition, the existing technology can generally only achieve a frequency ratio of about 2.0. The complementary structure of the folded electric dipole end structure and the reverse extension branch of the present invention can achieve a small frequency ratio of about 1.3, and has the advantages of high gain and wide impedance bandwidth at high frequencies.

[0054] Specifically, the thickness of the first magnetic dipole unit is 6.5-8 mm.

[0055] As a preferred embodiment, the thickness of the first magnetic dipole unit is only 7 mm, which is approximately 0.051 wavelengths (calculated based on the center frequency of the low frequency).

[0056] As a preferred embodiment, the first patch assembly 2 includes a first patch 21 and a second patch 22, the medium 1 has a first surface and a second surface relative to each other along the thickness direction, the first patch 21 is arranged on the first surface, the second patch 22 is arranged on the second surface, and the feeding end 4 is arranged on the second surface.

[0057] The first short-circuit component 3 includes a first section 31, a second section 32, and a third section 33, which are sequentially arranged around the dielectric 1. The two ends of the second section 32 are respectively connected to the first section 31 and the third section 33. The first section 31 is connected to the first patch 21 and the second patch 22 on both sides along the Z-axis, the second section 32 is connected to the first patch 21 and the second patch 22 on both sides along the Z-axis, and the third section 33 is connected to the first patch 21 and the second patch 22 on both sides along the Z-axis. With this arrangement, the first section 31, the second section 32, and the third section 33 can enclose the first patch 21 and the second patch 22 to focus energy, while the other sides are open to radiate energy.

[0058] Furthermore, the first folding structure 6 includes a first radiation component and a second short-circuit component, the first radiation component includes a first upper arm 61 and a first lower arm 62 arranged in parallel, the first upper arm 61 and the first lower arm 62 extend along the +X axis direction, the second short-circuit component includes a first strip 63, the first strip 63 extends along the Z axis direction, and the ends of the first strip 63 are respectively connected to the first upper arm 61 and the first lower arm 62 to form a first "U-shaped" structure.

[0059] In detail, the first patch 21 is connected to the first lower arm 62 through the second strip line 82.

[0060] Furthermore, the second folding structure 7 includes a second radiation component and a third short-circuit component, the second radiation component includes a second upper arm 71 and a second lower arm 72 arranged in parallel, the second upper arm 71 and the second lower arm 72 extend along the -X axis direction, the third short-circuit component includes a second strip 73, the second strip extends along the Z axis direction, and the ends of the second strip 73 are respectively connected to the second upper arm 71 and the second lower arm 72 to form a second "U-shaped" structure.

[0061] Specifically, the second patch 22 is connected to the second upper arm 71 through the first strip line 81 .

[0062] In a preferred embodiment, the end of the first upper arm 61 closest to the second upper arm 71 is the first end, and the end of the second upper arm 71 closest to the first upper arm 61 is the second end. The edge shape of the first end matches the edge shape of the second end. In detail, the first end has a first protrusion, and the second end has a first reverse-extending branch that matches the first protrusion. The first reverse-extending branch is a first concave portion formed inwardly along the second end, so that the first protrusion and the first concave portion form a complementary structure.

[0063] In a preferred embodiment, the end of the first lower arm 62 closest to the second lower arm 72 is the third end, and the end of the second lower arm 72 closest to the first lower arm 62 is the fourth end. The edge shape of the third end matches the edge shape of the fourth end. Specifically, the fourth end has a second inner recess, and the third end has a second reverse-extending branch that matches the second inner recess. The second reverse-extending branch is a second protrusion formed along the outer edge of the third end. Thus, the second inner recess and the second protrusion form a complementary structure.

[0064] It should be noted that if the connection mode of the first folding structure 6 and the second folding structure 7 is adjusted, right-hand circular polarization can be generated in the first direction (ie, +Y direction). Figure 3 As shown, specifically, the first folding structure 6 and the second folding structure 7 are interchanged in the X-axis direction, so that the positions of the first upper arm 61 and the second upper arm 71 are interchanged. At the same time, the positions of the first lower arm 62 and the second lower arm 72 are interchanged, and the second upper arm 71 is still connected to the first belt line 81, and the first lower arm 62 is still connected to the second belt line 82.

[0065] Preferably, the planar end-fire dual-frequency circularly polarized antenna further includes a feed coaxial cable, which is arranged at the feed end 4 and extends along the Z direction.

[0066] As a preferred embodiment, the dielectric constant of the medium is 1-20.

[0067] Preferably, the medium is air with a dielectric constant of 1.0006.

[0068] In a specific embodiment of the present invention, the reference values ​​are as follows: definition: L is the length of the first magnetic dipole unit, L is 85-95 mm, preferably, L=90 mm; W is the width of the first magnetic dipole unit, W is 42-47 mm, preferably, W=45 mm; H is the height (thickness) of the first magnetic dipole unit, H is 6.5-8 mm, preferably, H=7 mm; WO is the width of the first strip line 81, WO is 1.5-2.5 mm, preferably, W0=2.5 ​​mm; L1 is the length of the first belt line 81, L1 is 20-26 mm, preferably, L1=25 mm; L2 is the length of the second lower arm 72, L2 is 32-34 mm, preferably, L2=32.25 mm; W1 is the depth of the first inner concave portion of the first end of the first upper arm 61, W1 is 1.7-1.8 mm, W1=1.75 mm; W2 is the distance between the first upper arm 61 and the second upper arm 71 along the X-axis direction, W2 is 0.95-1.05 mm, W2=1 mm; W_X is the width of the second electric dipole unit along the Y-axis direction. Preferably, W_X=32.5 mm. Since the medium here is air, there is no limited range for the width.

[0069] Specifically, the simulation curve diagram of the present invention is as follows: Figure 10 This is a simulation of the antenna's S11. The simulated S11 curve resonates at 2.18 GHz and 2.80 GHz. The figure also shows that the antenna's S11 falls below -10 dB at low frequencies (2.14-2.19 GHz, bandwidth 0.05 GHz, 2.31%) and at high frequencies (2.73-2.83 GHz, bandwidth 0.10 GHz, 3.60%).

[0070] Figure 11 This is the antenna axial ratio simulation diagram. The antenna axial ratio is lower than 3dB for low frequency: 2.15-2.27GHz (bandwidth 0.12GHz, 5.43%), and high frequency 2.68-2.97GHz (bandwidth 0.29GHz, 10.27%).

[0071] Figure 12 This is the antenna gain simulation diagram. The low-frequency gain of the antenna is around 2dB, and the high-frequency gain is greater than 6dB.

[0072] Figure 13 、 14, 15, and 16 are the directional patterns of the antenna at the two resonance points of 2.18 GHz and 2.80 GHz in the XOY and YOZ planes. It is not difficult to find that the left-hand gain is greater than the right-hand gain at 90 degrees, which belongs to left-hand circular polarization. The maximum radiation direction is in the +Y direction, and the directional pattern has good stability.

[0073] The following is a detailed introduction to the deduction process of the model of the present invention: Figure 17 、 Figure 18 、 Figure 19 The three models are a deduction process of the model: Figure 20 、 Figure 21 Revealed Figure 19 The evolution of the folded electric dipole at the upper and lower surfaces of the model at approximately complementary structures.

[0074] Combine Figure 22 、 Figure 23 、 Figure 24 As can be seen, Model 1 can only achieve single-frequency coverage at 2.4 GHz with an axial ratio greater than 12 dB. To achieve dual-band coverage and improve the axial ratio, Model 2 fully utilizes the upper and lower surfaces of the dielectric layer and introduces a second electric dipole element (i.e., a folded electric dipole antenna). As shown in the figure, this structure can achieve dual-band coverage at both the low-frequency 2.15 GHz and high-frequency 2.82 GHz, with an axial ratio of less than 3 dB. The frequency ratio is approximately 1.31. The second electric dipole element provides a horizontally polarized component, while the first magnetic dipole element (i.e., a rectangular microstrip magnetic dipole antenna) provides a vertically polarized component. At low frequencies, the rectangular microstrip magnetic dipole antenna operates in its fundamental mode, while the folded electric dipole element is fully active and maintains an effective length of one-quarter wavelength at low frequencies. At high frequencies, the rectangular microstrip magnetic dipole antenna operates in a higher-order mode, while a portion of the folded electric dipole generates current and maintains an effective length of one-quarter wavelength at high frequencies. However, the reflection coefficient center frequency has a low overlap with the axial ratio center frequency, resulting in a narrow overlapping operating bandwidth. In order to improve the working bandwidth of the antenna, Model 3 introduced a complementary structure and optimized the shape to achieve a dual-frequency effect of low frequency 2.18GHz and high frequency 2.76GHz, and the overlapping area with the axis ratio center frequency is wider, achieving a small frequency ratio characteristic of 1.27, while the gain loss to the center frequency is very small.

[0075] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0076] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0077] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio, characterized by: include, A first magnetic dipole unit, configured to provide a dual-frequency vertically polarized component, the first magnetic dipole unit comprising a dielectric, a first patch component, a first short-circuit component, and a feeding end, the first patch component and the first short-circuit component forming a first cavity, the dielectric being disposed in the first cavity, and an opening being formed at one end of the first cavity for radiating energy in a first direction; The feeding end is provided on the first patch component; a second electric dipole unit, configured to provide a dual-frequency horizontal polarization component, the second electric dipole unit comprising a first folded structure and a second folded structure, the second folded structure being a reverse folded structure of the first folded structure and forming a complementary structure with the first folded structure at an end; A delay line unit, wherein the first magnetic dipole unit and the second electric dipole unit are connected through the delay line unit to provide the orthogonal phase difference required for circular polarization; the delay line unit includes a first strip line and a second strip line parallel to each other along the first direction, one end of the first strip line is connected to the first patch component, and the other end is connected to the second folding structure; one end of the second strip line is connected to the first patch component, and the other end is connected to the first folding structure.

2. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 1, characterized in that: The first patch assembly includes a first patch and a second patch. The medium has a first surface and a second surface opposite to each other along the thickness direction. The first patch is arranged on the first surface, the second patch is arranged on the second surface, and the feeding end is arranged on the second surface.

3. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 2, characterized in that: The first short-circuit component includes a first section, a second section, and a third section sequentially arranged around the medium, wherein two ends of the second section are respectively connected to the first section and the third section.

4. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 1, characterized in that: The first folding structure includes a first radiation component and a second short-circuit component, the first radiation component includes a first upper arm and a first lower arm arranged in parallel, the second short-circuit component includes a first strip, and the ends of the first strip are respectively connected to the first upper arm and the first lower arm to form a first "U-shaped" structure.

5. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 4, characterized in that: The second folding structure includes a second radiation component and a third short-circuit component, the second radiation component includes a second upper arm and a second lower arm arranged in parallel, the third short-circuit component includes a second strip, and the ends of the second strip are respectively connected to the second upper arm and the second lower arm to form a second "U-shaped" structure.

6. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 5, characterized in that: The end of the first upper arm close to the second upper arm is the first end, and the end of the second upper arm close to the first upper arm is the second end. The edge shape of the first end and the edge shape of the second end are complementary; the first end has a first protrusion, and the second end has a first reverse-extending branch node matching the first protrusion, and the first reverse-extending branch node is a first concave portion formed inwardly along the second end.

7. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 5, characterized in that: The end of the first lower arm close to the second lower arm is the third end, and the end of the second lower arm close to the first lower arm is the fourth end. The edge shape of the third end is complementary to the edge shape of the fourth end; the fourth end has a second inner recess, and the third end has a second reverse-extending branch node matching the second inner recess, and the second reverse-extending branch node is a second protrusion formed along the outward bulge of the third end.

8. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 1, characterized in that: It also includes a feeding coaxial cable, which is arranged at the feeding end and extends along the Z direction.

9. The planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to claim 1, characterized in that: The dielectric constant of the medium is 1-20.

10. A planar end-fire dual-frequency circularly polarized antenna with a small frequency ratio according to any one of claims 1 to 9, characterized in that: The length of the first magnetic dipole is 85-95 mm, the width is 42-47 mm, and the height is 6.5-8 mm; the length of the first strip line and the second strip line is 20-26 mm.

Images