Dual-band dual-circularly polarized end-fire antenna unit

Abstract

The utility model provides a double -frequent double circular polarization end -firing antenna unit, double -frequent double circular polarization end -firing antenna unit, including broadband double circular polarization antenna radiator, the connecting structure based on substrate integrated waveguide and double -frequent asymmetric feed structure, double -frequent asymmetric feed structure includes Ku frequency band feed structure and Ka frequency band feed structure, broadband double circular polarization antenna radiator with Ku frequency band feed structure and Ka frequency band feed structure realizes integrated fusion through multiplexing part the connecting structure based on substrate integrated waveguide, the utility model realizes the scheme that different medium layer substrate integrated waveguide input TE10 mode respectively changes into left -handed circular polarization wave and right -handed circular polarization wave, and the polarization structure of same dielectric constant that the upper and lower symmetry of stretching out will ensure that the main beam direction of antenna first frequency band and second frequency band can all be by end -firing direction radiation, has improved the directivity of antenna unit, has ensured that antenna unit can realize wideband impedance matching and excellent axial ratio performance in K / Ka wave band, and the efficiency of optimization signal reception and emission.

Description

Technical Field

[0001] This utility model belongs to the field of end-fire antennas, specifically a dual-frequency dual-circular polarization end-fire antenna unit. Background Technology

[0002] Circularly polarized antennas, with their excellent polarization matching characteristics and high directional gain, can effectively suppress multipath fading in satellite-to-ground links, attracting significant attention in millimeter-wave satellite-to-ground communications. However, in compact scenarios such as handheld terminals, traditional side-fired circularly polarized antennas are susceptible to polarization mismatch due to interference from the equipment's metal backplate, and performance degradation is also easily caused by user hand obstruction. In contrast, end-fired circularly polarized antennas not only have a concentrated radiation pattern but also effectively avoid the influence of metal structures in confined spaces, making them more suitable for terminal integration. Building on this, dual-band dual-circularly polarized end-fired antennas further achieve the ability to radiate left-handed / right-handed circularly polarized waves in two frequency bands respectively. This supports the application requirements of different transmit and receive frequency bands while effectively suppressing inter-band interference, improving system communication efficiency and reliability. Compared to traditional patch-based side-fired dual-band circularly polarized antennas, the end-fired structure breaks through the limitation of radiation direction, making it more suitable for systems that need to radiate circularly polarized beams along a planar direction, showing broad application prospects in modern RF front-ends such as satellite communications and radar systems.

[0003] However, the design of dual-band dual-circularly polarized end-fire antennas still faces multiple challenges: on the one hand, it is necessary to simultaneously achieve dual-wideband circularly polarized radiation with a frequency ratio of 1.4 and good impedance matching under low profile constraints; on the other hand, it is essential to suppress the mutual coupling between Ku and Ka band elements to avoid beam shift and axial ratio degradation. Therefore, how to maintain the stability of impedance matching and circular polarization performance in each band while controlling dual-band coupling has become a key challenge for its practical application. Currently, most mainstream solutions use two independently designed band elements combined with a decoupling structure. Although this can basically achieve functional integration, it often leads to an increase in antenna size and makes it difficult to balance high isolation and circular polarization stability over a wide bandwidth, thus limiting its widespread application in compact terminals.

[0004] In recent years, various end-fire dual-circularly polarized antenna structures have been proposed, mainly focusing on metal ridge waveguide schemes. These structures achieve circular polarization by generating electric field components with equal amplitude and orthogonal phase through their own mode design. However, their manufacturing relies on high-precision CNC processes, resulting in high costs. Furthermore, these antennas typically use air as the dielectric, making it difficult to reduce their profile and limiting their embedding applications in thin and light terminals. Although side-fire dual-band dual-circularly polarized antennas are easier to achieve in terms of electrical performance, their radiation mechanism limits their ability to fully meet the communication requirements of terminal devices.

[0005] In summary, this utility model provides a dual-frequency dual-circularly polarized end-fire antenna unit to solve the above problems. Utility Model Content

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0007] The dual-frequency dual-circularly polarized end-fire antenna unit includes a broadband dual-circularly polarized antenna radiator, a connection structure based on a substrate integrated waveguide, and a dual-frequency asymmetric feeding structure. The dual-band asymmetric feeding structure includes a Ku-band feeding structure and a Ka-band feeding structure. The broadband dual-circularly polarized antenna radiator is integrated with the Ku-band feeding structure and the Ka-band feeding structure through a shared portion of the substrate-integrated waveguide-based connection structure. It also includes a fourth metal layer, a third dielectric layer, a third metal layer, a second dielectric layer, a second metal layer, a first dielectric layer, and a first metal layer stacked from top to bottom. Each of the first to fourth metal layers has a defect ground structure etched on it to realize magnetic dipole radiation. The first to third dielectric layers are provided with metallized vias for guiding or limiting electromagnetic wave transmission, namely, a first metallized via, a second metallized via, and a third metallized via.

[0008] Furthermore, in this invention, the broadband dual-circular polarized antenna radiator is composed of three dielectric substrates with the same dielectric constant and four metal layers symmetrically distributed about the second dielectric layer. The left end of the broadband dual-circular polarized antenna radiator is a beamforming region composed of a pure dielectric radiator, whose horizontal cross-section is composed of isosceles trapezoids and rectangles connected together. The wide side of the rectangle is smaller than the mode conversion region formed by the connection structure based on the substrate integrated waveguide. The first and third dielectric layers each have two rows of parallel first metallized vias, and their positions are symmetrical with the second dielectric layer. The second metallized vias in the second dielectric layer are distributed in an N-shape. The first and fourth metal layers, the second and third metal layers all have defect ground structures. The defect ground structures on the first and fourth metal layers are composed of trapezoids and semi-ellipses superimposed. The defect ground structures on the second and third metal layers are trapezoidal. The first and fourth metal layers have a reserved annular non-copper area with the same size as the outer conductor of the feed probe.

[0009] Furthermore, in this invention, the dielectric substrate located in the second dielectric layer includes two first non-metallized vias and multiple third metallized vias distributed around them, for enhancing the isolation between the two ports.

[0010] Furthermore, in this invention, the connection structure based on substrate integrated waveguide is composed of two layers of substrate integrated waveguide with a dielectric layer sandwiched in between.

[0011] Furthermore, in this invention, the first dielectric layer and the third dielectric layer are substrate integrated waveguide structures with defective ground.

[0012] Furthermore, in this invention, the first dielectric layer of the connection structure based on the substrate integrated waveguide is composed of two different dielectric substrates spliced ​​together, while the second and third dielectric layers are both composed of a single dielectric substrate. The first and third dielectric layers are provided with two rows of metallized vias, while the second dielectric layer has no metallized vias.

[0013] Furthermore, in this invention, the dual-frequency asymmetric power supply structure also includes a coaxial probe with an SMPM interface. On the second and third metal layers, two annular non-copper-clad areas of different sizes are etched in the coupling area corresponding to the inner conductor of the coaxial probe, which are used to compensate for the parasitic inductance introduced by the inner conductor.

[0014] Furthermore, in this invention, multiple metallized vias located in the second dielectric layer form two annular arrays, respectively surrounding the two first non-metallized vias, to form a port isolation structure.

[0015] Furthermore, in this invention, a metal block or a double-layer copper-clad dielectric substrate is provided below the bottom edge of the trapezoidal structure of the defect ground structure of the first metal layer and above the bottom edge of the defect ground structure of the fourth metal layer, to enhance the electric field in the vertical direction and optimize the axial ratio performance.

[0016] Beneficial effects: This utility model has the following beneficial effects: This invention achieves a scheme to convert the TE10 mode input from substrate integrated waveguides with different dielectric layers into left-hand circularly polarized waves and right-hand circularly polarized waves, respectively. By using a symmetrical polarization structure with the same dielectric constant along the extended vertical direction, it ensures that the main beam directions of the antenna in both the first and second frequency bands can radiate from the end-fire direction, improving the directivity of the antenna element. This ensures that the antenna element can achieve broadband impedance matching and excellent axial ratio performance in the K / Ka bands, optimizing signal reception and transmission efficiency. The use of conductive adhesive to bond substrates with different dielectric constants to form the connection structure between the radiator and the feed structure allows the low-frequency impedance bandwidth to be optimized to below -10dB, thus achieving excellent performance for the dual-frequency dual-circularly polarized end-fire antenna. The dual-frequency dual-circularly polarized end-fire antenna radiator, the substrate integrated waveguide-based connection structure, and the asymmetric dual-frequency feed structure are closely integrated in physical layout, providing balanced performance while effectively saving layout space. Simultaneously… Because the dual-band dual-circularly polarized radiator was designed with full consideration of circular polarization performance in two different frequency bands, the complex decoupling design requirements in dual-band antenna design were cleverly reduced. At the same time, the scheme of bonding different dielectric substrates with conductive adhesive made it feasible to design a dual-port isolation structure with metallized vias and non-metallized through-holes in the middle layer. This ensured excellent axial ratio performance, wide impedance bandwidth, and high port isolation in the design of the dual-band dual-circularly polarized end-fire antenna. Attached Figure Description

[0017] Figure 1 This is a perspective view of the dual-frequency dual-circularly polarized end-fire antenna unit provided by the present invention; Figure 2 This is a side view of the dual-frequency dual-circularly polarized end-fire antenna unit provided by the present invention; Figure 3 This is a top view of the first metal layer of the dual-frequency dual-circular polarization unit provided by the present invention; Figure 4 This is a top view of the second metal layer of the dual-frequency dual-circular polarization unit provided by the present invention; Figure 5 This is a top view of the third metal layer of the dual-frequency dual-circular polarization unit provided by the present invention; Figure 6 This is a top view of the fourth metal layer of the dual-frequency dual-circular polarization unit provided by the present invention; Figure 7 This is a top view of the second dielectric layer of the dual-frequency dual-circular polarization unit provided by the present invention; Figure 8 The simulation results of the low-frequency reflection coefficient of the antenna element provided by this invention are shown in the figure. Figure 9 The simulation results of the low-frequency gain of the antenna element provided by this invention are shown in the figure. Figure 10 The simulation results of the low-frequency axial ratio bandwidth of the antenna element provided by this invention are shown in the figure. Figure 11 The simulation results of the high-frequency reflection coefficient of the antenna element provided by this invention are shown in the figure. Figure 12 The simulation results of the high-frequency gain of the antenna unit provided by this invention are shown in the figure. Figure 13 The simulation results of the high-frequency axial ratio bandwidth of the antenna unit provided by this invention are shown in the figure.

[0018] In the picture: 1. Dual-band dual-circularly polarized antenna radiator; 2. Connection structure based on substrate integrated waveguide; 3. Ku-band feed structure; 4. Ka-band feed structure; 5. Coaxial probe; 6. Defect ground structure; 7. Circular non-copper clad area; 8. Double-layer copper clad dielectric substrate; 9. Beamforming area; 10. Mode conversion area; 11. First metal layer; 12. Second metal layer; 13. Third metal layer; 14. Fourth metal layer; 21. First dielectric layer; 22. Second dielectric layer; 23. Third dielectric layer; 31. First metallized via; 32. Second metallized via; 33. Third metallized via; 34. First non-metallized via. Detailed Implementation

[0019] To better understand the technical content of this utility model, specific embodiments are described below in conjunction with the accompanying drawings. Various aspects of this utility model are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily defined to include all aspects of this utility model. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in this utility model are not limited to any particular implementation. Furthermore, some aspects of this utility model can be used alone or in any suitable combination with other aspects disclosed in this utility model.

[0020] Example 1 This is the first embodiment of the present invention, which provides a dual-frequency dual-circularly polarized end-fire antenna unit, including a broadband dual-circularly polarized antenna radiator 1, a connection structure 2 based on a substrate integrated waveguide, and a dual-frequency asymmetric feeding structure. The dual-band asymmetric feeding structure includes a Ku-band feeding structure 3 and a Ka-band feeding structure 4. The broadband dual-circularly polarized antenna radiator 1 is integrated with the Ku-band feeding structure 3 and the Ka-band feeding structure 4 through a connection structure 2 based on a substrate integrated waveguide. It also includes a fourth metal layer 14, a third dielectric layer 23, a third metal layer 13, a second dielectric layer 22, a second metal layer 12, a first dielectric layer 21, and a first metal layer 11 stacked from top to bottom. Each of the first metal layer 11 to the fourth metal layer 14 has a defect ground structure 6 for realizing magnetic dipole radiation. The first dielectric layer 21 to the third dielectric layer 23 are provided with metallized vias for guiding or limiting electromagnetic wave transmission, namely, a first metallized via 31, a second metallized via 32, and a third metallized via 33.

[0021] The broadband dual-circular polarized antenna radiator is located at the left end of the antenna element and is the key part for realizing electromagnetic wave radiation. Specifically, it can be divided into two functional areas, left and right. The left beamforming area 9 is composed of three dielectric substrates with the same horizontal cross-section. Its cross-sectional shape is a rectangular circumscribed isosceles trapezoid. The thickness of each of the three dielectric layers is 1.524 mm, and the thickness of the second dielectric layer 22 is 1.016 mm. This three-layer waveguide structure effectively optimizes the radiation pattern by shaping the wavefront, thereby achieving a higher vertex gain.

[0022] Right-hand mode conversion area 10: Please refer to this section as well. Figures 3 to 6 They each show a top view of a four-layer metal structure, which is composed of three dielectric substrates and four metal layers stacked alternately.

[0023] like Figure 3 and Figure 6 As shown, a trapezoidal circumscribed semi-ellipse defect structure 6 is etched at the left end of the four metal layers.

[0024] like Figure 4 and Figure 5 As shown, the left ends of the second metal layer 12 and the third metal layer 13 are etched with trapezoidal defect structures 6. Two rows of regularly distributed metallized vias are provided in both the first metal layer 11 and the third dielectric layer 23. The metal layers with defect structures 6 and the dielectric substrate with metallized vias work together to convert the TE10 mode electromagnetic waves fed by the connection structure into electromagnetic waves of equal amplitude and orthogonal phase with a 90° phase difference, ultimately synthesizing a circularly polarized wave that radiates towards the front end. Furthermore, the structure of the second dielectric layer 22 is shown below. Figure 7 The second metallized via 32 is distributed along the edge of the trapezoidal defect ground structure 6 to limit the lateral spread of electromagnetic waves and constrain the field distribution. A vertical double-layer copper-clad dielectric substrate is disposed below the bottom edge of the first metal layer 11 defect ground structure 6 and above the bottom edge of the fourth metal layer 14 defect ground structure 6, respectively, symmetrical about the second dielectric layer 22. This structure, in conjunction with the second metallized via 32, effectively enhances the electric field strength in the vertical direction, thereby optimizing the antenna's in-band axial ratio performance.

[0025] Example 2 This is the second embodiment of the present invention, which is based on the previous embodiment.

[0026] In this embodiment, the broadband dual-circular polarized antenna radiator 1 is composed of three dielectric substrates with the same dielectric constant and four metal layers symmetrically distributed about the second dielectric layer 22. The left end of the broadband dual-circular polarized antenna radiator 1 is a beamforming region 9 composed of a pure dielectric radiator, whose horizontal cross-section is composed of isosceles trapezoids and rectangles connected together. The wider side of the rectangle is smaller than the mode conversion region 10 formed by the connection structure 2 based on the substrate integrated waveguide. Two rows of parallel first metallized vias 31 are provided in the first dielectric layer 21 and the third dielectric layer 23, and their positions are... The second dielectric layer 22 is symmetrical, and the second metallized vias 32 in the second dielectric layer 22 are distributed in an N-shape. Defect ground structures 6 are provided on the first metal layer 11 and the fourth metal layer 14, the second metal layer 12 and the third metal layer 13. The defect ground structures 6 on the first metal layer 11 and the fourth metal layer 14 are composed of trapezoidal and semi-elliptical superpositions, and the defect ground structures 6 on the second metal layer 12 and the third metal layer 13 are trapezoidal. The first metal layer 11 and the fourth metal layer 14 have reserved annular non-copper areas 7 with the same size as the outer conductor of the feed probe.

[0027] The dielectric substrate located in the second dielectric layer 22 includes two first non-metallized vias 34 and multiple third metallized vias 33 distributed around them to enhance the isolation between the two ports.

[0028] The connection structure 2 based on substrate integrated waveguide consists of two layers of substrate integrated waveguide with a dielectric layer sandwiched in between.

[0029] The first dielectric layer 21 and the third dielectric layer 23 are substrate integrated waveguide structures with defective ground.

[0030] The first dielectric layer 21 of the interconnect structure 2 based on the substrate integrated waveguide is composed of two different dielectric substrates spliced ​​together. The second dielectric layer 22 and the third dielectric layer 23 are both composed of a single dielectric substrate. The first dielectric layer 21 and the third dielectric layer 23 are provided with two rows of metallized vias, while the second dielectric layer 22 has no metallized vias.

[0031] The dual-frequency asymmetric feeding structure also includes a coaxial probe 5 as an SMPM interface. On the second metal layer 12 and the third metal layer 13, two annular non-copper areas 7 of different sizes are etched in the coupling area corresponding to the inner conductor of the coaxial probe to compensate for the parasitic inductance introduced by the inner conductor.

[0032] Multiple metallized vias located in the second dielectric layer 22 form two annular arrays, which respectively surround the two first non-metallized vias 34 to form a port isolation structure.

[0033] A metal block or double-layer copper-clad dielectric substrate 8 is provided below the bottom edge of the trapezoidal structure of the defect ground structure 6 of the first metal layer 11 and above the bottom edge of the defect ground structure 6 of the fourth metal layer 14, to enhance the electric field in the vertical direction and optimize the axial ratio performance.

[0034] The substrate-integrated waveguide-based connection structure 2 is located between the radiator and the feed structure, with its horizontal cross-sectional dimensions consistent with both. It consists of two substrate-integrated waveguide structures sandwiching a dielectric layer. The first dielectric layer 21 is composed of two dielectric substrates, TLY-5 and Rogers 4003. The spacing between the two rows of metal vias on the Rogers 4003 substrate is 0.2 mm larger than that on the TLY-5 substrate; this design optimizes impedance matching in the Ku-band. The second dielectric layer 22 and the third dielectric layer 23 both use TLY-5 dielectric substrates. The connection structure portion of the second dielectric layer 22 has no metal vias, while the third dielectric layer 23 has two rows of equally spaced metal vias. All four metal layers of the connection structure are rectangular structures consistent with the cross-section of the dielectric substrate.

[0035] The dual-frequency asymmetric feed structure is located at the rightmost end of the antenna element. It is used to receive external signals and excite the pilot mode in SIW. Its stacked structure from top to bottom is: SMPM feed probe, fourth metal layer 14, third dielectric layer 23, third metal layer 13, second dielectric layer 22, second metal layer 12, first dielectric layer 21, first metal layer 11, and SMPM feed probe.

[0036] The first metal layer 11 and the fourth metal layer 14 have a ring-shaped non-copper area 7 with the same size as the outer conductor of the feed probe, ensuring good contact between the probe's outer conductor and the metal layer. The second metal layer 12 and the third metal layer 13 have ring-shaped non-copper areas etched on them, with their centers coinciding with the center of the inner conductor of the feed probe for the corresponding frequency band. By coordinating the inner and outer diameters of this ring, the parasitic inductance of the probe can be precisely compensated and the resonant point adjusted, thereby optimizing the impedance matching for the corresponding frequency band.

[0037] For material and port isolation design, the first dielectric layer 21 uses Rogers 4003 with a relative permittivity of 3.55 and a dielectric loss of [value missing]. The second dielectric layer 22 and the third dielectric layer 23 use TLY-5 with a relative permittivity of 2.2 and a dielectric loss of [value missing]. The metal vias in both the first and third dielectric layers 21 and 23 are H-shaped. Specifically, the lateral metal vias in the first dielectric layer 21 are offset to the left [λ / 4, λ / 3] relative to the lateral metal vias in the third dielectric layer 23. This design optimizes in-band impedance matching while allowing the coupling regions of the two-port probes and the SIW to be staggered, significantly improving the dual-port isolation. The metal via layout of the second dielectric layer 22 is derived by rotating around the horizontal center of the two feed probes. The centers of the two non-metallized vias coincide with the probe centers and are each surrounded by eight metallized vias, forming an isolation enhancement structure to further suppress inter-port coupling.

[0038] Example 3 Reference Figure 8-13 This is the third embodiment of the present invention, which is based on the first two embodiments.

[0039] In this embodiment, the SIW with dual-frequency asymmetric feed structure includes multiple first metallized vias 31 arranged in an H-shape. By adjusting the position of the transverse vias in the propagation direction of this H-shaped structure, the distance between them and the probe can be equal to λ / 4, thereby efficiently converting the TEM mode to the TE10 mode and optimizing the impedance bandwidth. The preferred diameter range of the second metallized via 32 is [D / 3, D / 2], where D is the diameter of the first metallized via. This range is the best choice for optimizing the axial ratio bandwidth.

[0040] The diameter of the third metallized via 33 is also preferably within the range of [D / 3, D / 2] to achieve the best balance between processing technology and port isolation effect. The eccentricity k of the semi-elliptical defect ground structure 6 on the first metal layer 11 and the fourth metal layer 14 is preferably 0.2. This value was determined after extensive experimental verification and can achieve the best balance between optimizing the axial ratio in the low-frequency range and maintaining good impedance matching.

[0041] like Figure 8-13As shown, the antenna element provided in this embodiment has the following outstanding advantages: Through SIW and common aperture design, dual-band Ka / Ku, dual-circular polarization left / right-hand end-fire radiation is simultaneously achieved within a single profile element, possessing wide impedance bandwidth, wide axial ratio bandwidth, and high port isolation. Using coaxial probe feeding and SIW technology, combined with conductive adhesive bonding of different dielectric substrates, in-band impedance matching of the dual-band dual-circular polarization antenna is achieved simultaneously through independent optimization of the feeding structure, facilitating integration into terminal equipment. Through a series of innovative solutions such as dual-band asymmetric feeding structure, metallized via equivalent magnetic walls, and symmetrical copper-clad dielectric substrates, parasitic parameters are effectively compensated, mode conversion efficiency is optimized, and back radiation is suppressed, ultimately achieving high gain and excellent circular polarization purity. The decoupling problem between the two bands is considered at the system level; a sophisticated physical layout and via design replace complex additional decoupling circuits, simplifying the structure and reducing manufacturing costs while ensuring performance.

[0042] All standard parts used in this application can be purchased from the market, and can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. The control method is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art and is common knowledge in the field. Since this application is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail in this application.

[0043] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A dual-frequency, dual-circularly polarized end-fire antenna element, characterized in that: It includes a broadband dual-circularly polarized antenna radiator (1), a connection structure based on a substrate integrated waveguide (2), and a dual-frequency asymmetric feeding structure; The dual-band asymmetric feeding structure includes a Ku-band feeding structure (3) and a Ka-band feeding structure (4). The broadband dual-circular polarized antenna radiator (1) and the Ku-band feeding structure (3) and the Ka-band feeding structure (4) are integrated by reusing part of the substrate-integrated waveguide-based connection structure (2). It also includes a fourth metal layer (14), a third dielectric layer (23), a third metal layer (13), a second dielectric layer (22), a second metal layer (12), a first dielectric layer (21), and a first metal layer (11) stacked from top to bottom. The first metal layer (11) to the fourth metal layer (14) are all etched with a defect ground structure (6) for realizing magnetic dipole radiation. The first dielectric layer (21) to the third dielectric layer (23) are provided with metallized vias for guiding or limiting electromagnetic wave transmission, namely a first metallized via (31), a second metallized via (32), and a third metallized via (33).

2. The dual-frequency dual-circularly polarized end-fire antenna unit as described in claim 1, characterized in that: The broadband dual-circular polarized antenna radiator (1) is composed of three dielectric substrates with the same dielectric constant and four metal layers symmetrically distributed about the second dielectric layer (22). The left end of the broadband dual-circular polarized antenna radiator (1) is a beamforming region (9) composed of a pure dielectric radiator. Its horizontal cross-section is composed of isosceles trapezoids and rectangles, and the wide side of the rectangle is smaller than the mode conversion region (10) formed by the connection structure (2) based on the substrate integrated waveguide. The first dielectric layer (21) and the third dielectric layer (23) each have two rows of parallel first metallized vias (31), and their positions are symmetrical with the second dielectric layer (22). The second metallized via (32) in the second dielectric layer (22) is distributed in an N-shape. The first metal layer (11) and the fourth metal layer (14), the second metal layer (12) and the third metal layer (13) are all provided with defect ground structures (6). The defect ground structures (6) on the first metal layer (11) and the fourth metal layer (14) are composed of trapezoidal and semi-elliptical superpositions. The defect ground structures (6) on the second metal layer (12) and the third metal layer (13) are trapezoidal. The first metal layer (11) and the fourth metal layer (14) have reserved annular non-copper areas (7) with the same size as the outer conductor of the feed probe.

3. The dual-frequency dual-circularly polarized end-fire antenna element as described in claim 1, characterized in that: The dielectric substrate located in the second dielectric layer (22) includes two first non-metallized vias (34) and multiple third metallized vias (33) distributed around it, for enhancing the isolation between the two ports.

4. The dual-frequency dual-circularly polarized end-fire antenna element as described in claim 1, characterized in that: The connection structure (2) based on substrate integrated waveguide consists of two layers of substrate integrated waveguide with a dielectric layer sandwiched in between.

5. The dual-frequency dual-circularly polarized end-fire antenna element as described in claim 1, characterized in that: The first dielectric layer (21) and the third dielectric layer (23) are substrate integrated waveguide structures with defective ground.

6. The dual-frequency dual-circularly polarized end-fire antenna unit as described in claim 1, characterized in that: The first dielectric layer (21) of the connection structure (2) based on substrate integrated waveguide is composed of two different dielectric substrates spliced ​​together. The second dielectric layer (22) and the third dielectric layer (23) are both composed of a single dielectric substrate. The first dielectric layer (21) and the third dielectric layer (23) are provided with two rows of metallized vias, while the second dielectric layer (22) has no metallized vias.

7. The dual-frequency dual-circularly polarized end-fire antenna element as described in claim 1, characterized in that: The dual-frequency asymmetric feeding structure also includes a coaxial probe (5) as an SMPM interface. On the second metal layer (12) and the third metal layer (13), two annular non-copper areas (7) of different sizes are etched in the coupling area corresponding to the inner conductor of the coaxial probe to compensate for the parasitic inductance introduced by the inner conductor.

8. The dual-frequency dual-circularly polarized end-fire antenna unit as described in claim 3, characterized in that: Multiple metallized vias located in the second dielectric layer (22) form two annular arrays, respectively surrounding the two first non-metallized vias (34) to form a port isolation structure.

9. The dual-frequency dual-circularly polarized end-fire antenna element as described in claim 1, characterized in that: A metal block or double-layer copper-clad dielectric substrate (8) is provided below the bottom edge of the trapezoidal structure of the defect ground structure (6) of the first metal layer (11) and above the bottom edge of the defect ground structure (6) of the fourth metal layer (14) to enhance the electric field in the vertical direction and optimize the axial ratio performance.

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