A broadband circularly polarized high-gain low-sidelobe directional antenna and an antenna unit thereof

Abstract

This invention discloses a broadband circularly polarized high-gain low-sidelobe directional antenna and its antenna elements, belonging to the field of radar and communication technology. The circularly polarized high-gain low-sidelobe directional antenna consists of antenna elements, a feed network, a metal shielding cavity, and metal screws. The antenna elements employ a broadband circularly polarized microstrip antenna with dual feed points and double-layer patches. m×n antenna elements are arranged according to a specified element spacing rule, and the low-sidelobe excitation and beam direction of the low-sidelobe directional antenna are achieved by a single m×n-channel T-type power divider feed network. This invention has advantages such as high integration, simple structure, excellent electrical performance, and ease of mass production.

Description

Technical Field

[0001] This invention relates to the fields of radar and communication technology, and in particular to a broadband circularly polarized high-gain low-sidelobe directional antenna and its antenna element. Background Technology

[0002] To win modern information warfare, various weapon platforms need to be equipped with numerous electronic information systems to achieve multiple functions such as electronic reconnaissance and countermeasures, communication and navigation, identification of friend or foe, situational awareness, and remote control and telemetry. The abundance of wireless electronic devices makes the electromagnetic environment inside the platform and in space increasingly complex. Poor electromagnetic compatibility handling within the platform itself can easily lead to malfunctions or performance degradation of electronic equipment, such as reduced radar sensitivity, weakened communication anti-jamming capabilities, and reduced electronic guidance and control. Poor handling of electromagnetic signals radiated into external space makes the platform vulnerable to tracking and detection by the enemy. Low-sidelobe directional antennas have advantages such as narrow beamwidth, low sidelobes, and high gain. They not only improve the electronic system's anti-electromagnetic interference capabilities, counter-reconnaissance capabilities, and receiving sensitivity, but also reduce the platform's electromagnetic radiation in dangerous directions, thereby improving survivability. Circularly polarized electromagnetic waves can be received by antennas with arbitrary linear polarization, and can also receive incoming waves with arbitrary linear polarization, further improving the system's resistance to multipath propagation and rain / fog.

[0003] Microstrip antennas, characterized by their low profile, light weight, and ease of integration, have found widespread application in electronic reconnaissance and countermeasures, communication and navigation, IFF (Identification Friend or Foe), situational awareness, and remote control and telemetry. Furthermore, due to their ease of arraying and flexible feeding methods, microstrip antennas are often used as components of low-sidelobe array antennas. The operating bandwidth, gain, beamwidth, and sidelobe level of an array antenna largely determine the overall system's technical and tactical performance, and these parameters are interrelated, requiring trade-offs in engineering design. Based on this, this invention proposes a design method for a broadband low-sidelobe microstrip array antenna. However, conventional microstrip antennas have relatively narrow operating bandwidths.

[0004] In addition, low sidelobe antenna design is currently a hot topic and a challenge in array antenna design, and it is one of the key technologies that urgently need to be solved to achieve high-performance communication.

[0005] The design challenges of broadband circularly polarized low sidelobe directional antennas lie in:

[0006] 1) Antenna Element Design. Certain performance characteristics of a directional antenna depend on the performance of its arrayed antenna elements. These elements must meet requirements for directional antenna array size, impedance bandwidth, axial ratio bandwidth, and mutual coupling. Furthermore, the selected antenna element's feeding method should facilitate connection or integration with the feeding network.

[0007] 2) Feed Network Design. The form of the feed network depends on the arrangement of the array antennas and can achieve a large power distribution ratio. Currently, most directional antennas use feed networks composed of Wilkinson power dividers, which have the advantages of good port matching and high isolation between ports. However, its achievable power distribution ratio is relatively low, making it difficult to meet the high power distribution ratio requirements of directional antennas with low sidelobes.

[0008] 3) Integrated fabrication and design. Directional antennas typically employ separate design, fabrication, and assembly of the antenna elements and the feed network. This results in a large workload for manual debugging of the feed network later on, making it difficult to guarantee consistency across all ports. Furthermore, the inconsistencies in manual soldering during the assembly of the feed network and antenna elements also lead to uncertainties in the output amplitude of each port, making it difficult to achieve the required low sidelobe levels. Summary of the Invention

[0009] The purpose of this invention is to provide a broadband circularly polarized high-gain low-sidelobe directional antenna and its antenna element. It employs an integrated design of the antenna radiating dielectric layer and the stripline feed network dielectric layer, along with multilayer printed circuit board (PCB) processing technology. This avoids the manual adjustment required for ordinary microstrip feed networks, reduces manual assembly steps, and significantly improves the production efficiency, low sidelobe performance, and yield of the directional antenna. This is beneficial for the mass production and engineering applications of low-sidelobe directional antennas.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A broadband circularly polarized antenna element includes, from top to bottom, a parasitic patch layer, a metal cavity, a radiating patch layer, an upper feed network layer, a lower feed network layer, and a metal shielding cavity.

[0012] The parasitic patch dielectric layer includes a first dielectric substrate, and a parasitic patch is provided on the lower surface of the first dielectric substrate;

[0013] The metal cavity is used to provide support and positioning for the parasitic patch layer and the radiation patch layer;

[0014] The radiation patch layer includes a second dielectric substrate, and a radiation patch is provided on the upper surface of the second dielectric substrate;

[0015] The upper layer of the power supply network includes a third dielectric substrate, the upper surface of which is provided with a metal ground plane, and a circular hole is opened on the upper metal ground plane; the lower surface of the third dielectric substrate is provided with a Wilkinson power divider power supply network; the Wilkinson power divider power supply network is connected to the radiating patch on the upper surface of the second dielectric substrate through a short-circuit post that passes through the second dielectric substrate and the third dielectric substrate, and the short-circuit post passes through the circular hole of the upper metal ground plane.

[0016] The lower layer of the power supply network includes a fourth dielectric substrate, and a lower metal ground plane is provided on the lower surface of the fourth dielectric substrate.

[0017] Furthermore, the parasitic patch has a hexagonal structure, which is a square patch with a set of diagonals cut off.

[0018] Furthermore, the short-circuit post is a short-circuit metal post or a metallized through-hole.

[0019] Furthermore, the radiating patch has a square structure, with the center of the radiating patch directly opposite the center of the parasitic patch.

[0020] Furthermore, both the parasitic patch and the radiation patch are metal patches.

[0021] Furthermore, the edge of the first dielectric substrate is provided with a linear array of semi-metallic vias along the edge line; the semi-metallic vias penetrate the first dielectric substrate and one diameter of the semi-metallic vias coincides with the edge line.

[0022] A broadband circularly polarized high-gain low-sidelobe directional antenna includes a T-type feed network and a broadband circularly polarized antenna element as described above; a metal shielding cavity is also provided at the bottom of the lower metal ground plane, and the metal shielding cavity is fastened to the lower metal ground plane; the end of the surface-mount RF connector is exposed to the outside of the metal shielding cavity through a small hole at a corresponding position on the metal shielding cavity;

[0023] The semi-metallic vias of adjacent broadband circularly polarized antenna elements face each other, forming a complete metallic via; the Wilkinson power divider feed network of each broadband circularly polarized antenna element is connected by a T-type feed network, forming a complete directional antenna feed network; the input and output ports of the directional antenna feed network are connected to surface-mount RF connectors, and the port impedance matching is adjusted by an impedance matching joint.

[0024] Furthermore, it includes m×n broadband circularly polarized antenna elements, where m≥4 and n≥4.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The broadband circularly polarized antenna element of the present invention has a low profile, excellent electrical performance, is easy to expand and array in two dimensions, is easy to integrate with the feed network, and has a high degree of integration.

[0027] 2. The integrated design of the antenna radiating layer and the stripline feed network dielectric layer of the present invention, along with the multilayer printed circuit board process, avoids the manual debugging of ordinary microstrip feed networks, greatly improving the production efficiency of the product.

[0028] 3. Furthermore, the integrated design and multi-layer printed circuit board processing of this invention avoids manual debugging of the feed network and reduces manual assembly steps in the production process of low sidelobe directional antennas, thus ensuring the low sidelobe performance of the directional antenna and improving production efficiency and yield.

[0029] 4. Furthermore, the present invention also has the advantages of simple structure, low profile, and easy mass production. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural diagram of the antenna unit in an embodiment of the present invention.

[0031] Figure 2 This is a cross-sectional structural diagram of the antenna element in an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram showing the corresponding positions of the radiating patch, parasitic patch, and Wilkinson power divider feed network in the antenna unit of this invention.

[0033] Figure 4 This is a schematic cross-sectional view of the low sidelobe directional antenna in an embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the feed network layout for the low sidelobe directional antenna in an embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of the 1 / 4 feed network and the feed power distribution topology of the low sidelobe directional antenna in this embodiment of the invention.

[0036] Figure 7 This refers to the voltage standing wave ratio (VSWR) within the operating bandwidth range of this embodiment of the invention.

[0037] Figure 8 It is the normal axis ratio within the operating bandwidth range of this embodiment of the invention.

[0038] Figure 9 This refers to the normal gain within the operating bandwidth range of this embodiment of the invention.

[0039] Figure 10 This is a normalized gain pattern of the E-plane and H-plane at low frequency points in the low operating frequency band of this invention.

[0040] Figure 11 This is a normalized gain pattern of the E-plane and H-plane at the mid-frequency point in the low operating frequency band of this invention.

[0041] Figure 12 This is a normalized gain pattern of the E-plane and H-plane at high frequency points in the low operating frequency band according to an embodiment of the present invention.

[0042] Figure 13This is a normalized gain pattern of the E-plane and H-plane at low frequency points in the high operating frequency band according to an embodiment of the present invention.

[0043] Figure 14 This is a normalized gain pattern of the E-plane and H-plane at a mid-frequency point in the high operating frequency band according to an embodiment of the present invention.

[0044] Figure 15 This is a normalized gain pattern of the E-plane and H-plane at high-frequency points in the high-operating frequency band of an embodiment of the present invention.

[0045] In the diagram: 1. Parasitic patch layer; 2. Parasitic patch; 3. Radiating patch; 4. Radiating patch layer; 5. Metal cavity; 6. Upper metal ground plane; 7. Upper layer of feed network; 8. Lower layer of feed network; 9, 14. Wilkinson power divider feed network; 10. Lower metal ground plane; 11. Metal shielded cavity; 12. RF connector; 13. Impedance matching joint; 15. Semi-metallic via; 16. Metal screw; 17. Dual feed point. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. However, the embodiments described herein are only some embodiments of the present invention, and 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.

[0047] Reference Figure 1 and Figure 2 A broadband circularly polarized antenna element, from top to bottom, includes a parasitic patch layer, a metal cavity, a radiating patch layer, an upper feed network layer, and a lower feed network layer;

[0048] The parasitic patch layer includes a first dielectric substrate, with no metal layer on the upper surface and a parasitic patch on the lower surface.

[0049] The metal cavity provides support and positioning for the radiating layer and parasitic layer of the antenna unit;

[0050] The radiating patch layer includes a second dielectric substrate, with a radiating patch on the upper surface of the second dielectric substrate and an exposed substrate on the lower surface without copper plating.

[0051] The upper layer of the feed network includes a third dielectric substrate; the upper surface of the third dielectric substrate is provided with an upper metal ground plane, and a circular hole is opened on the upper metal ground plane; the upper metal ground plane is located between the second dielectric substrate and the third dielectric substrate; a Wilkinson power divider feed network is provided on the lower surface of the third dielectric substrate, and the Wilkinson power divider feed network is connected to the radiating patch on the upper surface of the second dielectric substrate through a short-circuit post that passes through the second dielectric substrate and the third dielectric substrate, and the short-circuit post passes through the circular hole of the upper metal ground plane; the broadband circularly polarized antenna element adopts dual-feed point feeding of the radiating patch.

[0052] The lower layer of the power supply network includes a fourth dielectric substrate, which is located below the Wilkinson power divider power supply network. The upper surface of the fourth dielectric substrate is bare and has no copper plating, while the lower surface has a metal ground plane.

[0053] Furthermore, the first dielectric substrate has a through-hole semi-metallic via at its edge.

[0054] Furthermore, both the parasitic patch and the radiation patch are metal patches.

[0055] Furthermore, the parasitic patch is square with one of its opposite corners cut off.

[0056] Furthermore, the radiation patch is square.

[0057] Furthermore, the short-circuit post is a short-circuit metal post or a metallized through-hole.

[0058] A broadband circularly polarized high-gain low-sidelobe directional antenna includes the aforementioned broadband circularly polarized antenna elements, each arranged in an array. The Wilkinson power divider feed network of each antenna element is connected to the low-sidelobe T-type feed network of the directional antenna, forming a complete low-sidelobe directional antenna feed network. The input and output ports of the feed network are connected to surface-mount RF connectors, and the port impedance matching is adjusted using impedance matching sections. A metal shielding cavity is also provided at the bottom of the lower metal ground plane of the feed network, and the metal shielding cavity is attached to the lower metal ground plane of the feed network. The end of the surface-mount RF connector is exposed to the outside of the metal shielding cavity through a small hole at a corresponding position on the metal shielding cavity.

[0059] Furthermore, the size of the directional antenna is the array size m×n, where m≥4 and n≥4.

[0060] Reference Figure 3 In this embodiment, the parasitic patch layer consists of only one dielectric substrate. The upper surface of the dielectric substrate is bare and has no copper coating. The lower surface is provided with m×n parasitic patches 2. The parasitic patches are square with a corner cut off at one of the diagonals to extend the impedance bandwidth and axial ratio bandwidth of the antenna.

[0061] Reference Figure 4In this embodiment, the radiating patch layer, the upper layer of the stripline feed network, and the lower layer of the stripline feed network are all fabricated using a multilayer printed circuit board process. The upper surface of the radiating patch layer substrate has m×n radiating patches 3, and the lower surface is bare substrate without copper plating. The upper surface of the stripline feed network upper substrate has an upper metal ground plane 6, which serves as both the upper metal ground plane of the stripline feed network and the metal ground plane of the antenna element. The metal ground plane has 2×m×n circular vias. The lower surface has a stripline Wilkinson power divider feed network 9. The upper surface of the lower substrate of the stripline feed network has a bare substrate without copper plating. The lower surface has a lower metal ground plane 10, which has openings for RF input / output ports. The metal ground planes on the upper surface of the dielectric substrate of the stripline feed network and the metal ground planes on the lower surface of the dielectric substrate have vertical semi-metallic vias for suppressing mode resonance along the edge of the feed network traces. The semi-metallic vias of adjacent broadband circularly polarized antenna elements are aligned, forming complete metal vias.

[0062] The parasitic patch layer of the low sidelobe directional antenna consists of a dielectric substrate. The substrate material and thickness can be designed according to the antenna's operating frequency band. In this embodiment, the substrate of the parasitic patch dielectric layer is Ruilong RA300A with a thickness of 1.016mm.

[0063] The radiating patch layer of the low sidelobe directional antenna consists of a dielectric substrate. The substrate material and thickness can be designed according to the antenna's operating frequency band. In this embodiment, the substrate of the radiating patch dielectric layer is Ruilong RA300A with a thickness of 2.286mm.

[0064] The upper layer of the stripline feed network of the low sidelobe directional antenna consists of a dielectric substrate. The substrate material and thickness can be designed according to the antenna's operating frequency band. In this embodiment, the upper dielectric substrate of the stripline feed network is TLY-5Z with a thickness of 0.762mm.

[0065] The lower layer of the stripline feed network of the low sidelobe directional antenna consists of a dielectric substrate. The substrate material and thickness can be designed according to the antenna's operating frequency band. In this embodiment, the upper dielectric substrate of the stripline feed network is TLY-5Z with a thickness of 0.762mm.

[0066] The directional antenna consists of broadband circularly polarized antenna elements arranged according to a specified element spacing rule, with an array size of m×n (m≥4, n≥4; here we take 4×8 as an example).

[0067] In addition, the low sidelobe directional antenna also includes an RF connector 12, a metal cavity 5, a metal shielding cavity 11, and a metal screw 16.

[0068] Figure 1This is a three-dimensional structural diagram of the directional antenna in the above embodiment. The low-sidelobe directional antenna consists of broadband circularly polarized antenna elements arranged according to a certain spacing rule.

[0069] Figure 3 This is a schematic diagram of the main module structure of the antenna element of the directional antenna in the above embodiment. The radiating patch of the broadband circularly polarized antenna element adopts orthogonal dual-feed points, with the two feed points having equal amplitudes and a 90° phase difference to achieve the radiation of circularly polarized electromagnetic waves, implemented through a Wilkinson power divider feed network. Parasitic patches are added to extend the impedance bandwidth of the antenna element. The chamfered shape of the parasitic patches is used to extend the axial ratio bandwidth of the antenna element.

[0070] Figure 4 This is a cross-sectional structural diagram of the directional antenna in the above embodiment. The low-sidelobe directional antenna, from top to bottom, includes a parasitic patch dielectric layer of a broadband circularly polarized antenna element, a parasitic patch, a metal cavity, a radiating patch, a radiating patch dielectric layer, a metal ground plane of the antenna element, an upper dielectric layer of the stripline feed network of the low-sidelobe directional antenna, a stripline feed network, a lower dielectric layer of the stripline feed network, a metal ground plane, and a metal shielding cavity.

[0071] Figure 5 This is a schematic diagram of the feed network layout for the directional antenna in the above embodiment. It employs an integrated design of a dual-feed power divider network for broadband circularly polarized antenna elements and a low-sidelobe feed network.

[0072] Figure 6 This diagram illustrates the 1 / 4 feed network and power distribution topology of the directional antenna in the above embodiment. Because the excitation amplitude and phase of each broadband circularly polarized antenna element in the low sidelobe directional antenna are axisymmetric, only the power distribution topology of the 1 / 4 network is shown here. In this invention, a feed network composed of parallel T-type power dividers is used to achieve equal-phase unequal-affinity excitation at the feed ports of each broadband circularly polarized antenna element. The T-type power divider has a simple structure, low insertion loss, and can achieve a high power division ratio.

[0073] Figure 7 It is the voltage standing wave ratio (VSWR) of the above embodiments within the operating bandwidth range. Figure 8 It is the normal axis ratio within the operating bandwidth range of the above embodiments. Figure 9 This refers to the normal gain within the operating bandwidth range of the above embodiments. Figure 10 This is the normalized gain pattern of the E-plane and H-plane at the low-frequency point in the low-operating frequency band of the above embodiment. Figure 11 This is the normalized gain pattern of the E-plane and H-plane at the mid-frequency point in the low operating frequency band of the above embodiment. Figure 12 This is the normalized gain pattern of the E-plane and H-plane at high frequencies in the low operating frequency band of the above embodiment. Figure 13This is the normalized gain pattern of the E-plane and H-plane at the low frequency point in the high operating frequency band of the above embodiment. Figure 14 This is the normalized gain pattern of the E-plane and H-plane at the mid-frequency point of the above embodiment in the high operating frequency band. Figure 15 This is the normalized gain pattern of the E-plane and H-plane at high-frequency points in the high-frequency band of the above embodiment.

[0074] from Figures 7-8 As can be seen, the voltage standing wave ratio (VSWR) of the above embodiments is less than 2 and the normal axis ratio is less than 3 throughout the entire operating frequency band. Figure 9 The normal gain of the above embodiment covers the entire operating frequency band. The normal gain is related to the size of the directional antenna; here, the normal gain is 16dBi to 18dBi. From... Figures 10-15 As can be seen, in the above embodiments, the sidelobe levels of the E-plane and H-plane at low, medium, and high frequency points are less than -27.3dB in both low and high operating frequency bands. The above embodiments exhibit excellent electrical performance and have promising prospects for engineering applications.

Claims

1. A broadband circularly polarized antenna element, characterized in that, It includes, from top to bottom, a parasitic patch layer, a metal cavity, a radiating patch layer, an upper feed network layer, a lower feed network layer, and a metal shielding cavity; The parasitic patch dielectric layer includes a first dielectric substrate, and a parasitic patch is provided on the lower surface of the first dielectric substrate; The metal cavity is used to provide support and positioning for the parasitic patch layer and the radiation patch layer; The radiation patch layer includes a second dielectric substrate, and a radiation patch is provided on the upper surface of the second dielectric substrate; The upper layer of the feed network includes a third dielectric substrate, and the upper surface of the third dielectric substrate is provided with a metal ground plate, and a circular hole is opened on the upper metal ground plate. The lower surface of the third dielectric substrate is provided with a Wilkinson power divider feed network; The Wilkinson power divider feed network is connected to the radiating patch on the upper surface of the second dielectric substrate through a short-circuit post that passes through the second and third dielectric substrates, and the short-circuit post passes through a circular hole in the upper metal ground plane. The lower layer of the power supply network includes a fourth dielectric substrate, and a lower metal ground plane is provided on the lower surface of the fourth dielectric substrate. The parasitic patch has a hexagonal structure, which is a square patch with one set of diagonals cut off; The radiating patch has a square structure, with the center of the radiating patch facing the center of the parasitic patch. Both the parasitic patch and the radiating patch are metal patches; the edge of the first dielectric substrate is provided with a linear array of semi-metallic vias along the edge line; the semi-metallic vias penetrate the first dielectric substrate and one diameter of the semi-metallic vias coincides with the edge line.

2. The broadband circularly polarized antenna element according to claim 1, characterized in that, The short-circuit post is a short-circuit metal post or a metallized through-hole.

3. A broadband circularly polarized high-gain low-sidelobe directional antenna, comprising a T-type feed network, characterized in that, It also includes a broadband circularly polarized antenna unit as described in any one of claims 1 to 2; the bottom of the lower metal ground plane is further provided with a metal shielding cavity, which is fastened to the lower metal ground plane; the end of the surface-mount RF connector is exposed to the outside of the metal shielding cavity through a small hole at a corresponding position on the metal shielding cavity; The semi-metallic vias of adjacent broadband circularly polarized antenna elements face each other, forming a complete metallic via; the Wilkinson power divider feed network of each broadband circularly polarized antenna element is connected by a T-type feed network, forming a complete directional antenna feed network; the input and output ports of the directional antenna feed network are connected to surface-mount RF connectors, and the port impedance matching is adjusted by an impedance matching joint.

4. A broadband circularly polarized high-gain low-sidelobe directional antenna according to claim 3, characterized in that, It includes m×n broadband circularly polarized antenna elements, where m≥4 and n≥4.

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