A wideband circularly polarized antenna element and array thereof

Abstract

The application discloses a broadband circularly polarized antenna unit and an array thereof, and belongs to the technical field of antennas, and solves the problems of large unit spacing and single polarization form of the existing circularly polarized antenna unit when being arrayed; the first, second, third and fourth straight waveguides are all cavity structures with an upper opening; the first and second straight waveguides and the third and fourth straight waveguides are connected through waveguide elbow connectors; the first, second, third and fourth straight waveguides surround a symmetric mouth-shaped structure with upper and lower openings; when two electromagnetic signals with a phase difference of 180 DEG are respectively fed from the bottoms of the first and third straight waveguides, the antenna unit generates left-handed circularly polarized radiation; when two electromagnetic signals with a phase difference of 180 DEG are respectively fed from the bottoms of the second and fourth straight waveguides, the antenna unit generates left-handed circularly polarized radiation; the antenna unit can flexibly switch the polarization state, realizes left-handed or right-handed circularly polarized radiation, and can realize polarization multiplexing.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology and relates to a wideband circularly polarized antenna element and its array. Background Technology

[0002] Wireless communication utilizes electromagnetic waves to achieve long-distance transmission. Antennas, as devices for transmitting or receiving electromagnetic waves, play an irreplaceable role in modern wireless communication technology. In communication and interaction between electronic devices, an antenna acts as an energy sensor. When used as a transmitting device, it converts high-frequency current signals guided by a feed line into electromagnetic wave signals radiated into space; when used as a receiving device, it converts radio electromagnetic wave signals in space into high-frequency current signals conducted by a feed line, thus enabling information transmission. Since antennas began to demonstrate their practical value, they have become an indispensable part of people's daily lives.

[0003] Antennas can be classified in many ways. From a polarization perspective, antennas can be divided into linearly polarized antennas and circularly polarized antennas. For linearly polarized antennas, in many practical scenarios, firstly, due to the limitations of the working platform, the placement of transmitting and receiving antennas may not be completely consistent; secondly, even if they are placed consistently, linearly polarized waves may experience Faraday rotation when passing through special media such as magnetic fields, thus changing their polarization direction; furthermore, for many mobile devices, the antenna placement angle is even random and constantly changing. In an extreme case, if the polarization directions of two linearly polarized antennas are perpendicular to each other, they will be unable to transfer energy and therefore cannot achieve communication functionality.

[0004] Circular polarization overcomes the limitations of linear polarization by employing its operating mode. For two circularly polarized antennas with identical rotation, since the electric field polarization covers the entire plane, neither different placement angles nor electric field rotation effects result in energy loss. Furthermore, the reflected wave from a circularly polarized wave encountering an obstacle exhibits the opposite rotation pattern to the incident wave, which is highly beneficial for addressing multipath effects in communication. Due to these advantages, circularly polarized antennas are in high demand in numerous applications, such as navigation systems, aircraft control systems, indoor wireless network coverage systems, and radio frequency identification (RFID) systems.

[0005] Polarization multiplexing of circularly polarized antennas refers to the ability of a single antenna structure to produce both left-handed and right-handed circularly polarized radiation. Based on electromagnetic theory, left-handed and right-handed circular polarization possess a "symmetrical" characteristic.

[0006] In the existing technology, Chinese invention patent application document "A Circularly Polarized Waveguide Standing Wave Antenna" published on May 5, 2010, with application publication number CN101702467A, discloses a circularly polarized antenna based on a four-ridge waveguide, which is composed of a feed waveguide, a coupling slot, and a four-ridge metal waveguide, and has the ability to perform circularly polarized radiation within the operating frequency band. However, the relative bandwidth of this antenna is less than 10%, and it can only generate a single circular polarization, lacking the ability to polarization multiplex, thus limiting the system's communication capacity. Chinese invention patent applications CN104538742A (published April 22, 2015) and CN105633587A (published June 1, 2016), entitled "A Circularly Polarized Waveguide Slot Antenna and Its Design Method," disclose two types of circularly polarized antennas based on waveguide slot structures. Their basic structure involves creating two types of radiating slots within the waveguide to form a circularly polarized antenna. However, these two types of circularly polarized antennas are difficult to fabricate in the millimeter-wave band due to limitations in manufacturing processes. Furthermore, the antennas are structurally complex, thick, and have a narrow circular polarization bandwidth. The document "Design of a Ka-band Broadband High-Gain Circularly Polarized Communication Antenna" (Chen Ming et al., Electronic Technology and Software Engineering, 2015) proposes a broadband high-gain circularly polarized horn antenna for use in communications. This design combines a horn antenna with a broadband grooved circularly polarized antenna. Although this antenna features wide bandwidth and high gain, its large horn aperture results in a large element spacing during array formation, which easily leads to grating lobes in the radiation pattern and thus low aperture efficiency of the array antenna.

[0007] In summary, existing waveguide circularly polarized antennas have the following drawbacks: 1) they do not consider polarization multiplexing; 2) they have a narrow operating bandwidth; 3) in order to achieve a wider impedance matching, they adopt a complex matching structure, which is complicated to manufacture and costly; 4) when arraying, the element spacing is large, and the radiation pattern is prone to grating lobes, resulting in low aperture efficiency of the array antenna. Summary of the Invention

[0008] The technical problem to be solved by this invention is how to design a wideband circularly polarized antenna element to solve the problems of excessively large element spacing and single polarization form when existing circularly polarized antenna elements are arrayed.

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0010] A broadband circularly polarized antenna element includes: a first straight waveguide (11), a second straight waveguide (12), a third straight waveguide (13), a fourth straight waveguide (14), and a waveguide bend connector (15); the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) are all cavity structures with openings at the top; the first straight waveguide (11) and the second straight waveguide (12) are connected by a waveguide bend connector (15), and the third straight waveguide (13) and the fourth straight waveguide (14) are connected by a waveguide bend connector (15). The head connector (15) is connected, and the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) form a symmetrical U-shaped structure with openings at the top and bottom. When two electromagnetic signals with a 180° phase difference are fed into the bottom of the first straight waveguide (11) and the third straight waveguide (13) respectively, the antenna element generates left-hand circular polarization radiation. When two electromagnetic signals with a 180° phase difference are fed into the bottom of the second straight waveguide (12) and the fourth straight waveguide (14) respectively, the antenna element generates right-hand circular polarization radiation.

[0011] The antenna element of the present invention is designed with a symmetrical structure. When the electromagnetic signal enters the antenna from a pair of straight waveguides, it generates left-hand circular polarization radiation. When it enters the antenna from another pair of straight waveguides, it generates right-hand circular polarization radiation. The antenna element can flexibly switch polarization states to achieve left-hand or right-hand circular polarization radiation. Therefore, the antenna element can achieve polarization multiplexing.

[0012] Furthermore, the process by which the antenna element generates left-hand circularly polarized radiation is as follows: a portion of the electromagnetic signal fed from the first straight waveguide (11) radiates from the top opening of the first straight waveguide (11), and another portion of the electromagnetic signal enters the second straight waveguide (12) through the waveguide elbow connector (15) between the first straight waveguide (11) and the second straight waveguide (12), and radiates from the top opening of the second straight waveguide (12). The electromagnetic waves radiated from the first straight waveguide (11) and the second straight waveguide (12) are positively polarized. The electromagnetic signals fed from the third straight waveguide (13) are radiated from the top opening of the third straight waveguide (13), and the other part of the electromagnetic signals enter the fourth straight waveguide (14) through the waveguide elbow connector (15) between the third straight waveguide (13) and the fourth straight waveguide (14), and radiate from the top opening of the fourth straight waveguide (14). The electromagnetic waves radiated from the third straight waveguide (13) and the fourth straight waveguide (14) are orthogonally polarized, have equal amplitudes, and have a phase difference of 90°.

[0013] Furthermore, the process by which the antenna unit generates right-hand circularly polarized radiation is as follows: a portion of the electromagnetic signal fed from the second straight waveguide (12) radiates from the top opening of the second straight waveguide (12), and another portion of the electromagnetic signal enters the first straight waveguide (11) through the waveguide elbow connector (15) between the first straight waveguide (11) and the second straight waveguide (12), and radiates from the top opening of the first straight waveguide (11). The electromagnetic waves radiated from the second straight waveguide (12) and the first straight waveguide (11) are positively polarized. The electromagnetic signals fed from the fourth straight waveguide (14) are radiated from the top opening of the fourth straight waveguide (14), and the other part of the electromagnetic signals enter the third straight waveguide (13) through the waveguide elbow connector (15) between the third straight waveguide (13) and the fourth straight waveguide (14), and radiate from the top opening of the third straight waveguide (13). The electromagnetic waves radiated from the fourth straight waveguide (14) and the third straight waveguide (13) are orthogonally polarized, have equal amplitudes, and have a phase difference of 90°.

[0014] Furthermore, the upper part of the front panel of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) is provided with multiple grass-leaf-shaped impedance matching gradient structures; the back plate of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) is provided with a first metal ridge, a second metal ridge, and a third metal ridge. The second metal ridge is arranged along the central axis of the inner back plate of the waveguide housing, and the first metal ridge and the third metal ridge are symmetrically arranged on both sides of the second metal ridge.

[0015] Furthermore, rectangular openings are provided on the side plates of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14), and the rectangular openings are used to connect the waveguide elbow connector (15); the waveguide elbow connector (15) includes: an arc-shaped metal shell (151), a top fan-shaped cover plate (152), and a bottom fan-shaped cover plate (153), and the arc-shaped metal shell (151), the top fan-shaped cover plate (152), and the bottom fan-shaped cover plate (153) are integrally formed to form a quarter-cylinder structure.

[0016] Furthermore, it also includes: multiple circular metal cylinders and multiple coaxial feeding structures (16); the lower parts of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) are all sealed, and circular metal cylinders are provided on the outer sides of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14). The coaxial feeding structure (16) is installed inside the circular metal cylinder and inserted into the cavity of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14).

[0017] Furthermore, the coaxial power supply structure (16) includes: an annular dielectric material structure (161), a coaxial inner conductor (162), and a dielectric sleeve (163); one end of the coaxial inner conductor (162) is inserted inside the annular dielectric material structure (161), and the other end of the coaxial inner conductor (162) is inserted inside the dielectric sleeve (163), and the annular dielectric material structure (161) and the dielectric sleeve (163) completely enclose the coaxial inner conductor (162).

[0018] Furthermore, it also includes: a left-handed spiral waveguide (20) and a right-handed spiral waveguide (30); the lower parts of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14) are all open; the left-handed spiral waveguide (20) is embedded in the middle of the right-handed spiral waveguide (30), and the output ends of the left-handed spiral waveguide (20) and the right-handed spiral waveguide (30) are respectively connected to the lower openings of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13), and the fourth straight waveguide (14).

[0019] Further, the left-handed spiral-fed waveguide (20) includes: a first left-handed vertical waveguide (201), a second left-handed vertical waveguide (202), a third left-handed vertical waveguide (203), and a left-handed horizontal waveguide (204); the first left-handed vertical waveguide (201) is vertically connected to the middle position of the lower surface of the left-handed horizontal waveguide (204), and the second left-handed vertical waveguide (202) and the third left-handed vertical waveguide (203) are respectively vertically connected to the left-handed horizontal waveguide (204). 4) The two ends of the upper surface; the first left-hand vertical waveguide (201), the second left-hand vertical waveguide (202), the third left-hand vertical waveguide (203), and the left-hand horizontal waveguide (204) form a connected waveguide cavity that is symmetrical about the first left-hand vertical waveguide (201); the upper openings of the second left-hand vertical waveguide (202) and the third left-hand vertical waveguide (203) are connected to the bottom openings of the first straight waveguide (11) and the third straight waveguide (13).

[0020] Further, the right-hand spiral-fed waveguide (30) includes: a first right-hand spiral vertical waveguide (301), a second right-hand spiral vertical waveguide (302), a third right-hand spiral vertical waveguide (303), and a right-hand spiral horizontal waveguide (304); the first right-hand spiral vertical waveguide (301) is vertically connected to the middle position of the lower surface of the right-hand spiral horizontal waveguide (304), and the second right-hand spiral vertical waveguide (302) and the third right-hand spiral vertical waveguide (303) are respectively vertically connected to the right-hand spiral horizontal waveguide (304). 4) The two ends of the upper surface; the first right-hand vertical waveguide (301), the second right-hand vertical waveguide (302), the third right-hand vertical waveguide (303), and the right-hand horizontal waveguide (304) form a connected waveguide cavity that is symmetrical about the first right-hand vertical waveguide (301); the upper openings of the second right-hand vertical waveguide (302) and the third right-hand vertical waveguide (303) are connected to the bottom openings of the second straight waveguide (12) and the fourth straight waveguide (14).

[0021] An antenna array employing the aforementioned wideband circularly polarized antenna elements, wherein the antenna array is arranged in a rectangular or triangular configuration.

[0022] The advantages of this invention are:

[0023] (1) The antenna unit of the present invention is designed as a symmetrical structure. After the electromagnetic signal enters the antenna from a pair of straight waveguides, it generates left-hand circular polarization radiation. After entering the antenna from another pair of straight waveguides, it generates right-hand circular polarization radiation. The antenna unit can flexibly switch polarization states to achieve left-hand or right-hand circular polarization radiation. Therefore, the antenna unit can realize polarization multiplexing.

[0024] (2) The antenna unit of the present invention employs a variety of methods to achieve broadband matching. First, a coaxial feeding structure (16) is used, and a dielectric sleeve is provided on the inner conductor of the coaxial structure. This can effectively reduce the frequency sensitivity of the coaxial structure and is beneficial to the improvement of the antenna bandwidth. Second, a unique impedance matching gradient structure is used, which makes the antenna have non-frequency-varying characteristics to a certain extent. This is also beneficial to the improvement of the antenna bandwidth. The antenna unit has a wide bandwidth, which is far superior to other forms of antenna structure. At the same time, the matching structure is simple and easy to process.

[0025] (3) The antenna unit of the present invention incorporates a metal ridge in the waveguide structure, which can improve the structural strength of the antenna on the one hand, and reduce the size of the waveguide on the other hand; the size of the ridge waveguide structure can be significantly reduced compared with the traditional waveguide structure.

[0026] (4) When the antenna elements are arrayed, the spacing between the elements is small, the radiation pattern is less likely to produce grating lobes, and the aperture efficiency of the antenna array can be effectively improved; moreover, in some special application fields, such as satellite positioning, smaller grating lobes can also effectively improve the accuracy of the system.

[0027] (5) The antenna unit is made of all-metal material and has the advantages of high radiation efficiency and large power capacity. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural schematic diagram of a broadband circularly polarized antenna element according to Embodiment 1 of the present invention;

[0029] Figure 2 This is a top view of a broadband circularly polarized antenna element according to Embodiment 1 of the present invention;

[0030] Figure 3 This is a schematic diagram showing the connection between the first straight waveguide (11) and the second straight waveguide (12) of the broadband circularly polarized antenna unit in Embodiment 1 of the present invention;

[0031] Figure 4 This is a detailed structural view of the second straight waveguide (12) of the broadband circularly polarized antenna unit according to Embodiment 1 of the present invention, wherein (a) is the front perspective view of the second straight waveguide (12), (b) is the front perspective view of the second straight waveguide (12), (c) is the left perspective view of the second straight waveguide (12), and (d) is the top perspective view of the second straight waveguide (12);

[0032] Figure 5 This is a schematic diagram of the waveguide elbow connector (15) of the broadband circularly polarized antenna unit according to Embodiment 1 of the present invention;

[0033] Figure 6 This is a schematic diagram of the coaxial feeding structure (16) of the broadband circularly polarized antenna unit according to Embodiment 1 of the present invention;

[0034] Figure 7 This is an impedance matching characteristic curve of the wideband circularly polarized antenna element in the left-hand rotating operating state according to Embodiment 1 of the present invention.

[0035] Figure 8 This is a graph showing the axial ratio matching characteristics of the wideband circularly polarized antenna element in the left-hand rotating operating state according to Embodiment 1 of the present invention.

[0036] Figure 9 This is a three-dimensional structural schematic diagram of the improved broadband circularly polarized antenna element according to Embodiment 2 of the present invention;

[0037] Figure 10 This is an exploded perspective view of the three-dimensional structure of the improved broadband circularly polarized antenna element according to Embodiment 2 of the present invention.

[0038] Figure 11 This is a schematic diagram of the structure of the left-hand circularly polarized antenna element (20) of the improved broadband circularly polarized antenna element according to Embodiment 2 of the present invention;

[0039] Figure 12This is a schematic diagram of the structure of the right-hand circularly polarized antenna element (30) of the improved broadband circularly polarized antenna element according to Embodiment 2 of the present invention;

[0040] Figure 13 This is a schematic diagram of the antenna array structure of a rectangular array based on the wideband circularly polarized antenna element of Embodiment 2, according to Embodiment 3 of the present invention.

[0041] Figure 14 This is a schematic diagram of the antenna array structure of the triangular array based on the wideband circularly polarized antenna element of Embodiment 2, according to Embodiment 3 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0044] Example 1

[0045] like Figure 1 and Figure 2 As shown, a band-polarized waveguide antenna element includes: a first straight waveguide 11, a second straight waveguide 12, a third straight waveguide 13, a fourth straight waveguide 14, two waveguide elbow connectors 15, and four coaxial feed structures 16. The first straight waveguide 11 and the second straight waveguide 12 are connected by one waveguide elbow connector 15, and the third straight waveguide 13 and the fourth straight waveguide 14 are connected by one waveguide elbow connector 15. The first straight waveguide 11, the second straight waveguide 12, the third straight waveguide 13, and the fourth straight waveguide 14 form a symmetrical U-shaped structure with openings at the top and bottom. The four coaxial feed structures 16 are respectively inserted into the cavities of the first straight waveguide 11, the second straight waveguide 12, the third straight waveguide 13, and the fourth straight waveguide 14.

[0046] The first straight waveguide 11 and the third straight waveguide 13 have the same structure, and the second straight waveguide 12 and the fourth straight waveguide 14 have the same structure. The only difference between the first straight waveguide 11 and the second straight waveguide 12 is the direction of the rectangular opening on the side plate of the waveguide housing. The structural design of the straight waveguide is described below using the second straight waveguide 12 as an example.

[0047] like Figure 3 and Figure 4As shown, the second straight waveguide 12 includes: a waveguide housing 120, which is a semi-closed cavity structure with an open upper part and a sealed lower part. A rectangular opening 121 is provided on one side plate of the waveguide housing 120 for connecting the waveguide elbow connector 15; multiple grass-leaf-shaped impedance matching gradient structures 123 are provided on the upper part of the arc-shaped front panel 122 of the waveguide housing 120. The grass-leaf-shaped impedance matching gradient structures 123 enable the antenna element to have non-frequency-changing characteristics, which is beneficial to improving the bandwidth of the antenna element; a first gold... The waveguide housing 120 includes a first metal ridge 124, a second metal ridge 125, and a third metal ridge 126. The second metal ridge 125 is arranged along the central axis of the inner back plate of the waveguide housing 120. The first metal ridge 124 and the third metal ridge 126 are symmetrically arranged on both sides of the second metal ridge 125. A circular metal cylinder 127 is provided at the bottom of the outer side of the back plate of the waveguide housing 120. The circular metal cylinder 127 is connected to the cavity of the waveguide housing 120. The coaxial feed structure 16 is inserted into the circular metal cylinder 127. The length of the coaxial inner conductor 162 extending into the cavity of the waveguide housing 120 is adjustable, thereby adjusting the impedance matching effect of the antenna element.

[0048] like Figure 5 As shown, the waveguide elbow connector 15 includes: an arc-shaped metal shell 151, a top fan-shaped cover plate 152, and a bottom fan-shaped cover plate 153. The arc-shaped metal shell 151, the top fan-shaped cover plate 152, and the bottom fan-shaped cover plate 153 are integrally formed to form a quarter-cylinder structure.

[0049] like Figure 6 As shown, the coaxial feed structure 16 includes: a ring-shaped dielectric material structure 161, a coaxial inner conductor 162, and a dielectric sleeve 163. One end of the coaxial inner conductor 162 is inserted inside the ring-shaped dielectric material structure 161, and the other end of the coaxial inner conductor 162 is inserted inside the dielectric sleeve 163. The ring-shaped dielectric material structure 161 and the dielectric sleeve 163 completely enclose the coaxial inner conductor 162. The dielectric sleeve 163 can effectively reduce the frequency sensitivity of the coaxial structure, which is beneficial to improving the bandwidth of the antenna element.

[0050] The working principle of the antenna element in this embodiment is as follows:

[0051] like Figure 2 As shown, when two electromagnetic signals with a 180° phase difference are fed into the coaxial feed structure 16 at ports 1 and 3 respectively, the antenna element generates left-hand circularly polarized radiation. The specific process is as follows:

[0052] A portion of the electromagnetic signal input at port 1 radiates from the top opening of the first straight waveguide 11, while another portion enters the second straight waveguide 12 through the waveguide elbow connector 15 between the first straight waveguide 11 and the second straight waveguide 12, and radiates from the top opening of the second straight waveguide 12. The electromagnetic waves radiated from the first straight waveguide 11 and the second straight waveguide 12 are orthogonally polarized, have equal amplitude, and a 90° phase difference. A portion of the electromagnetic signal input at port 3 radiates from the top opening of the third straight waveguide 13, while another portion enters the fourth straight waveguide 14 through the waveguide elbow connector 15 between the third straight waveguide 13 and the fourth straight waveguide 14. Waveguide 14 radiates from the top opening of the fourth straight waveguide 14. The electromagnetic waves radiated from the third straight waveguide 13 and the fourth straight waveguide 14 are orthogonally polarized, have equal amplitude, and have a phase difference of 90°. Assuming that the phase of the electromagnetic signal fed into the coaxial feed structure 16 of port 1 is 0°, it can be seen from the above analysis that the phase of the electromagnetic signal radiated from the top opening of the first straight waveguide 11 is 0°, the phase of the electromagnetic signal radiated from the top opening of the second straight waveguide 12 is 90°, the phase of the electromagnetic signal radiated from the top opening of the third straight waveguide 13 is 180°, and the phase of the electromagnetic signal radiated from the top opening of the fourth straight waveguide 14 is 270°.

[0053] When two electromagnetic signals with a 180° phase difference are fed into the coaxial feed structure 16 at ports 2 and 4 respectively, the antenna element generates right-hand circular polarization radiation. The process is similar to that of left-hand circular polarization radiation, and will not be described in detail here.

[0054] Figure 7 The impedance matching characteristic curve is shown in the left-hand rotating operating state. According to the curve, the antenna element of this embodiment has good impedance matching characteristics in a wide frequency band.

[0055] Figure 8 The curve shows the axial ratio matching characteristics in the left-hand rotating operating state. According to the curve, the antenna element in this embodiment has good circular polarization axial ratio characteristics in a wide frequency band.

[0056] Example 2

[0057] In the broadband circularly polarized antenna element of Embodiment 1 of the present invention, the protruding circular metal cylinders 127 in adjacent antenna elements and the coaxial feed structure 16 installed inside them affect the array effect and cause the element spacing of the array to be too large. Therefore, this embodiment provides an improved broadband circularly polarized antenna element structure.

[0058] like Figure 9 and 10As shown, the improved antenna unit structure removes the circular metal cylinder 127 and does not use the coaxial feed structure 16. Instead, it adopts a left-handed spiral feed waveguide 20 and a right-handed spiral feed waveguide 30. Furthermore, the improved antenna structure opens the closed bottom of the first embodiment to connect with the left-handed spiral feed waveguide 20 and the right-handed spiral feed waveguide 30. The left-handed spiral feed waveguide 20 is embedded in the middle of the right-handed spiral feed waveguide 30.

[0059] like Figure 11 The diagram shows a schematic of the left-hand circular feed waveguide 20. The left-hand circular feed waveguide 20 includes: a first left-hand vertical waveguide 201, a second left-hand vertical waveguide 202, a third left-hand vertical waveguide 203, and a left-hand horizontal waveguide 204. The first left-hand vertical waveguide 201 is vertically connected to the middle of the lower surface of the left-hand horizontal waveguide 204. The second left-hand vertical waveguide 202 and the third left-hand vertical waveguide 203 are vertically connected to the two ends of the upper surface of the left-hand horizontal waveguide 204, respectively. The first left-hand vertical waveguide 201, the second left-hand vertical waveguide 202, the third left-hand vertical waveguide 203, and the left-hand horizontal waveguide 204 form a connected waveguide cavity that is symmetrical about the first left-hand vertical waveguide 201. The upper openings of the second left-hand vertical waveguide 202 and the third left-hand vertical waveguide 203 are connected to the bottom of the antenna element structure.

[0060] like Figure 12 The diagram shows a schematic of the right-hand spiral feed waveguide 30, which includes: a first right-hand spiral vertical waveguide 301, a second right-hand spiral vertical waveguide 302, a third right-hand spiral vertical waveguide 303, and a right-hand spiral horizontal waveguide 304. The first right-hand spiral vertical waveguide 301 is vertically connected to the middle of the lower surface of the right-hand spiral horizontal waveguide 304, and the second right-hand spiral vertical waveguide 302 and the third right-hand spiral vertical waveguide 303 are vertically connected to the two ends of the upper surface of the right-hand spiral horizontal waveguide 304, respectively. The first right-hand spiral vertical waveguide 301, the second right-hand spiral vertical waveguide 302, the third right-hand spiral vertical waveguide 303, and the right-hand spiral horizontal waveguide 304 form a connected waveguide cavity that is symmetrical about the first right-hand spiral vertical waveguide 301. The upper openings of the second right-hand spiral vertical waveguide 302 and the third right-hand spiral vertical waveguide 303 are connected to the bottom of the antenna element structure.

[0061] The working principle of the antenna element in this embodiment is as follows:

[0062] When the electromagnetic signal is fed into the bottom port of the first left-hand vertical waveguide 201, it will be divided into two parts and transmitted to the left and right sides of the left-hand horizontal waveguide 204 respectively. Based on waveguide theory, the two electromagnetic signals have the characteristics of equal amplitude and a phase difference of 180°. Then, the two electromagnetic waves are fed into the antenna element from the upper openings (port 1 and port 3) of the second left-hand vertical waveguide 202 and the third left-hand vertical waveguide 203 respectively, and finally radiate left-hand electromagnetic waves outward through the antenna element. For details, please refer to the working principle analysis of Embodiment 1.

[0063] When the electromagnetic signal is fed into the bottom port of the first right-hand vertical waveguide 301, it will be divided into two parts and transmitted to the left and right sides of the right-hand horizontal waveguide 304 respectively. Based on waveguide theory, the two electromagnetic signals have the characteristics of equal amplitude and a phase difference of 180°. Then, the two electromagnetic waves are fed into the antenna element from the upper openings (port 2 and port 4) of the second right-hand vertical waveguide 302 and the third right-hand vertical waveguide 303 respectively, and finally radiate right-hand electromagnetic waves outward through the antenna element. See the working principle analysis process of the antenna element in Embodiment 1.

[0064] Example 3

[0065] This embodiment provides an antenna array, which uses the antenna elements described in Embodiment 2, arranged in a rectangular or triangular array; as shown below. Figure 13 The diagram shown is a schematic of a rectangular array; as shown Figure 14 The diagram shows a triangular array. The antenna array in this embodiment can be manufactured using milling technology, a mature, reliable, widely applicable, and low-cost process. Based on milling, the antenna array can be machined as a single unit, rather than machining individual elements and then assembling them. This method ensures machining accuracy and reduces manufacturing costs.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wideband circularly polarized antenna element, characterized by, The application relates to a circularly-polarized antenna, which comprises a first straight waveguide (11), a second straight waveguide (12), a third straight waveguide (13), a fourth straight waveguide (14), a waveguide elbow connector (15), a left-rotating feed waveguide (20) and a right-rotating feed waveguide (30); the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) are all cavity structures with upper openings; the first straight waveguide (11) and the second straight waveguide (12) are connected through the waveguide elbow connector (15), the third straight waveguide (13) and the fourth straight waveguide (14) are connected through the waveguide elbow connector (15), the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) form a symmetric mouth-shaped structure with upper and lower openings; the lower parts of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) are all opened; when two electromagnetic signals with a 180-degree phase difference are fed into the bottom of the first straight waveguide (11) and the third straight waveguide (13) respectively, the antenna unit generates left-rotating circularly-polarized radiation; when two electromagnetic signals with a 180-degree phase difference are fed into the bottom of the second straight waveguide (12) and the fourth straight waveguide (14) respectively, the antenna unit generates right-rotating circularly-polarized radiation. The upper parts of the front panels of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) are all provided with a plurality of grass-leaf-shaped impedance matching gradient structures; the interiors of the back panels of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) are all provided with a first metal ridge, a second metal ridge and a third metal ridge; the second metal ridge is arranged along the central axis of the interior back panel of the waveguide shell, and the first metal ridge and the third metal ridge are symmetrically arranged on the two sides of the second metal ridge. The left-rotating feed waveguide (20) is embedded in the middle of the right-rotating feed waveguide (30), and the output ends of the left-rotating feed waveguide (20) and the right-rotating feed waveguide (30) are connected with the lower openings of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) respectively. ​ The left-handed feed waveguide (20) comprises a first left-handed vertical waveguide (201), a second left-handed vertical waveguide (202), a third left-handed vertical waveguide (203) and a left-handed horizontal vertical waveguide (204); the first left-handed vertical waveguide (201) is vertically connected to the middle position of the lower surface of the left-handed horizontal vertical waveguide (204), the second left-handed vertical waveguide (202) and the third left-handed vertical waveguide (203) are vertically connected to the two end positions of the upper surface of the left-handed horizontal vertical waveguide (204) respectively; the first left-handed vertical waveguide (201), the second left-handed vertical waveguide (202), the third left-handed vertical waveguide (203) and the left-handed horizontal vertical waveguide (204) form a waveguide cavity which is symmetrical about the first left-handed vertical waveguide (201); the upper end openings of the second left-handed vertical waveguide (202) and the third left-handed vertical waveguide (203) are connected to the bottom openings of the first straight waveguide (11) and the third straight waveguide (13); The right-handed feed waveguide (30) comprises a first right-handed vertical waveguide (301), a second right-handed vertical waveguide (302), a third right-handed vertical waveguide (303) and a right-handed horizontal vertical waveguide (304); the first right-handed vertical waveguide (301) is vertically connected to the middle position of the lower surface of the right-handed horizontal vertical waveguide (304), the second right-handed vertical waveguide (302) and the third right-handed vertical waveguide (303) are vertically connected to the two end positions of the upper surface of the right-handed horizontal vertical waveguide (304) respectively; the first right-handed vertical waveguide (301), the second right-handed vertical waveguide (302), the third right-handed vertical waveguide (303) and the right-handed horizontal vertical waveguide (304) form a waveguide cavity which is symmetrical about the first right-handed vertical waveguide (301); the upper end openings of the second right-handed vertical waveguide (302) and the third right-handed vertical waveguide (303) are connected to the bottom openings of the second straight waveguide (12) and the fourth straight waveguide (14); When electromagnetic signals are fed into the bottom port of the first left-handed vertical waveguide (201), the electromagnetic signals are divided into two parts which are transmitted to the left and right sides of the left-handed horizontal vertical waveguide (204) respectively, based on waveguide theory, the two parts of electromagnetic signals have the characteristics of equal amplitude and 180° phase difference, then the two parts of electromagnetic waves are fed into the antenna unit through the upper end openings of the second left-handed vertical waveguide (202) and the third left-handed vertical waveguide (203) respectively, and finally the left-handed electromagnetic waves are radiated outward through the antenna unit; When electromagnetic signals are fed into the bottom port of the first right-handed vertical waveguide (301), the electromagnetic signals are divided into two parts which are transmitted to the left and right sides of the right-handed horizontal vertical waveguide (304) respectively, based on waveguide theory, the two parts of electromagnetic signals have the characteristics of equal amplitude and 180° phase difference, then the two parts of electromagnetic waves are fed into the antenna unit through the upper end openings of the second right-handed vertical waveguide (302) and the third right-handed vertical waveguide (303) respectively, and finally the right-handed electromagnetic waves are radiated outward through the antenna unit.

2. A wideband circularly polarized antenna element according to claim 1, characterized in that The side plates of the first straight waveguide (11), the second straight waveguide (12), the third straight waveguide (13) and the fourth straight waveguide (14) are provided with rectangular openings for connecting waveguide elbow connectors (15); the waveguide elbow connector (15) comprises an arc-shaped metal shell (151), a top sector-shaped cover plate (152) and a bottom sector-shaped cover plate (153), which are integrally formed to form a quarter-cylinder structure.

3. An antenna array employing the wideband circularly polarized antenna element of any one of claims 1 to 2, wherein, The group array mode of the antenna array adopts a rectangular group array or a triangular group array.

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