Multi-band co-boresight circularly polarized antenna

Abstract

This invention provides a multi-band common-aperture circularly polarized antenna, relating to the field of common-aperture antenna technology. It includes a high-ratio antenna subarray, a low-ratio antenna subarray, an upper dielectric substrate, a lower dielectric substrate, via cavities, and a coaxial feed. The high-ratio and low-ratio antenna subarrays are symmetrically distributed about the center of the dielectric substrate on a double-layer dielectric substrate composed of the upper and lower dielectric substrates. The dielectric layer of the lower dielectric substrate has four rectangular metal-shielded via cavities, which are connected to the metal ground of the lower dielectric substrate. A low-frequency microstrip patch unit and a high-frequency microstrip patch unit constituting the high-ratio antenna subarray, and a microstrip patch unit constituting the low-ratio antenna subarray, are all directly coaxially fed. The multi-band common-aperture circularly polarized antenna proposed in this invention has the advantages of compact structure, low profile, simple feeding, easy fabrication, and flexible selection of operating frequency bands.

Description

Technical Field

[0001] This invention relates to the field of common aperture antenna technology, and more specifically to a multi-band common aperture circularly polarized antenna. Background Technology

[0002] Modern communication and navigation systems typically require high-density integration of a large number of electronic devices with different functions. In order to reduce the size of the system's radio frequency front-end, increase aperture utilization efficiency, improve integration, and reduce weight and cost, it is imperative to design multi-band, multi-polarization, and multi-operating mode antennas on the same aperture plane while ensuring the stable performance of each subsystem. Therefore, common aperture antenna technology has emerged.

[0003] Currently, most common common-aperture phased array antennas employ single-layer or stacked arrangements. Single-layer arrangements are limited by the physical area of ​​the radiating elements in each frequency band, increasing system size and reducing space utilization, failing to meet the miniaturization and multi-functionality requirements of modern communication and navigation systems. Stacked arrangements easily meet the miniaturization needs, but increase the profile height and the design difficulty of electromagnetic compatibility. Furthermore, stacked designs have poorer transmit / receive antenna isolation, causing mutual interference and degrading communication quality. The operating frequency ratio of the antenna is also limited due to the chosen common-aperture stacked design. Additionally, complex feed networks introduce additional insertion losses, significantly reducing antenna radiation efficiency.

[0004] It is evident that existing common-aperture antennas suffer from one or more drawbacks, such as low integration, high profile, complex structure, and inflexible selection of operating frequency bands, making them unsuitable for meeting the technical requirements of next-generation communication and navigation systems for low profile, lightweight, low cost, and multi-functional integrated passive antenna arrays. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a multi-band common-aperture circularly polarized antenna, which solves the problem that existing common-aperture antennas cannot scientifically and rationally integrate multiple functions.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A multi-band common-aperture circularly polarized antenna, the multi-band common-aperture circularly polarized antenna comprising:

[0010] High-frequency ratio antenna subarray, low-frequency ratio antenna subarray, upper dielectric substrate, lower dielectric substrate, through-hole cavity, and feed coaxial;

[0011] The high-frequency ratio antenna subarray and the low-frequency ratio antenna subarray are distributed on a double-layer dielectric substrate composed of an upper dielectric substrate and a lower dielectric substrate, and are symmetrical about the center of the double-layer dielectric substrate.

[0012] The high frequency ratio antenna subarray includes a low-frequency microstrip patch unit and a high-frequency microstrip patch unit, wherein the low-frequency microstrip patch unit is located on the upper surface of the lower dielectric substrate and the high-frequency microstrip patch unit is located on the upper surface of the upper dielectric substrate.

[0013] The low-frequency antenna subarray includes four first intermediate frequency microstrip patch units located on the upper surface of the lower dielectric substrate and four second intermediate frequency microstrip patch units located on the upper surface of the upper dielectric substrate.

[0014] The dielectric layer of the lower dielectric substrate is provided with four rectangular metal shielding via cavities, and the metal shielding via cavities are connected to the metal ground of the lower dielectric substrate.

[0015] The low-frequency microstrip patch unit, the high-frequency microstrip patch unit, the first intermediate-frequency microstrip patch unit, and the second intermediate-frequency microstrip patch unit are directly coaxially fed through a coaxial power supply.

[0016] Preferably, both the upper dielectric substrate and the lower dielectric substrate have a dielectric constant ε. r Rogers Ro4350b, a low-loss RF board with a voltage rating of 3.48.

[0017] Preferably, in order to achieve good matching, the low-frequency microstrip patch unit is provided with a low-frequency power supply coaxial cable; the first intermediate-frequency microstrip patch unit is provided with a first intermediate-frequency power supply coaxial cable; the second intermediate-frequency microstrip patch unit is provided with a second intermediate-frequency power supply coaxial cable; and the high-frequency microstrip patch unit is provided with a high-frequency power supply coaxial cable.

[0018] Preferably, the low-frequency microstrip patch unit has a circular clearance hole at the center of the patch.

[0019] Preferably, a metal through hole is provided in the center of the circular clearance hole.

[0020] Preferably, the low-frequency microstrip patch unit, the high-frequency microstrip patch unit, the first intermediate-frequency microstrip patch unit, and the second intermediate-frequency microstrip patch unit are all miniaturized chamfered circular polarization units.

[0021] Preferably, the first intermediate frequency microstrip patch unit is provided with a ring of metal shielding through holes around its perimeter, the metal shielding through holes being located on the lower dielectric substrate and connected to the metal ground.

[0022] Preferably, the four sides of the low-frequency microstrip patch unit, the high-frequency microstrip patch unit, the first intermediate-frequency microstrip patch unit, and the second intermediate-frequency microstrip patch unit are all cut with the same size, which correspond to low-frequency rectangular cuts, high-frequency rectangular cuts, first intermediate-frequency rectangular cuts, and second intermediate-frequency rectangular cuts, respectively.

[0023] (III) Beneficial Effects

[0024] This invention provides a multi-band common-aperture circularly polarized antenna. Compared with the prior art, it has the following advantages:

[0025] 1. This invention proposes a multi-band common-aperture circularly polarized antenna, comprising a high-ratio antenna subarray, a low-ratio antenna subarray, an upper dielectric substrate, a lower dielectric substrate, via cavities, and a coaxial feed. The high-ratio and low-ratio antenna subarrays are symmetrically distributed about the center of the dielectric substrate on a double-layer dielectric substrate composed of the upper and lower dielectric substrates. The dielectric layer of the lower dielectric substrate has four rectangular metal-shielded via cavities, which are connected to the metal ground of the lower dielectric substrate. A low-frequency microstrip patch unit and a high-frequency microstrip patch unit constituting the high-ratio antenna subarray, and a microstrip patch unit constituting the low-ratio antenna subarray, are all directly coaxially fed. The multi-band common-aperture circularly polarized antenna proposed in this invention has a compact structure, low profile, simple feeding, easy fabrication, and flexible selectable operating frequency bands. It can well meet the technical requirements of next-generation communication and navigation systems for low profile, lightweight, low-cost, and multi-functional integrated passive antenna arrays.

[0026] 2. This invention adopts a novel snowflake-shaped array method to integrate four antennas operating in different frequency bands onto the same aperture surface, realizing high-density aperture reuse. The overall antenna structure is simple and compact, small in size and light in weight, with strong engineering applicability and versatility, and is suitable for mass production.

[0027] 3. This invention introduces a miniaturized circularly polarized microstrip patch antenna, which adopts a simple coaxial direct feeding method, eliminating the complicated feeding network, reducing feeding loss, improving antenna radiation efficiency, and increasing the yield of finished products.

[0028] 4. This invention selects a thin and light double-layer dielectric substrate structure, with the overall antenna thickness not exceeding λ / 30. It has low profile characteristics, small radar cross section, and is easy to integrate between boards, making it suitable for airborne, spaceborne and other platforms with strict requirements for space and integration.

[0029] 5. The present invention introduces a metal via design at the center of the low-frequency microstrip patch unit, which reduces the mutual coupling between the stacked patches without affecting the low-frequency radiation performance; a metal shielding cavity structure is introduced around the first intermediate frequency microstrip patch unit, which improves near-frequency isolation and reduces the design difficulty of the back-end filter.

[0030] 6. The working frequency band of this invention covers high and low frequency bands with large frequency ratios, as well as mid-frequency bands with small frequency ratios. Compared with common aperture arrays with single frequency ratio coverage that are limited by antenna structure, the working frequency band of this antenna is more flexible and selectable, which can adapt to various communication and navigation application scenarios and increase the freedom of front-end radio frequency circuit design. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the overall structure of the multi-band common-aperture circularly polarized antenna in an embodiment of the present invention;

[0033] Figure 2 This is a top view of the multi-band common-aperture circularly polarized antenna in an embodiment of the present invention;

[0034] Figure 3 This is a top view of the upper microstrip patch array of the multi-band common-aperture circularly polarized antenna in an embodiment of the present invention;

[0035] Figure 4 This is a top view of the lower microstrip patch array of the multi-band common-aperture circularly polarized antenna in an embodiment of the present invention;

[0036] Figure 5 The simulation results of the standing wave ratio at the feed port of the low-frequency microstrip patch unit in the embodiment of the present invention;

[0037] Figure 6 This is the simulation result of the coupling coefficient between the low-frequency microstrip patch unit and all other units in the embodiment of the present invention;

[0038] Figure 7 The above are simulation results of the radiation pattern of the low-frequency microstrip patch unit in the embodiment of the present invention;

[0039] Figure 8 The simulation results of the axial ratio of the low-frequency microstrip patch unit in the embodiment of the present invention;

[0040] Figure 9 The above are simulation results of the standing wave ratio at the feed port of the high-frequency microstrip patch unit in this embodiment of the invention.

[0041] Figure 10 The simulation results show the coupling coefficients between the high-frequency microstrip patch unit and all other units in this embodiment of the invention.

[0042] Figure 11 The above are simulation results of the radiation pattern of the high-frequency microstrip patch unit in the embodiment of the present invention;

[0043] Figure 12 The simulation results of the axial ratio of the high-frequency microstrip patch unit in the embodiment of the present invention;

[0044] Figure 13 The above are the simulation results of the active standing wave at the feed ports of the four first intermediate frequency microstrip patch units in this embodiment of the invention.

[0045] Figure 14 The simulation results show the coupling coefficients between the first intermediate frequency microstrip patch unit and all other units in this embodiment of the invention.

[0046] Figure 15 This is a simulation result of the radiation pattern of the four first intermediate frequency microstrip patch units fed in an embodiment of the present invention;

[0047] Figure 16 The following are the axial ratio simulation results of the square feeding of the four first intermediate frequency microstrip patch units in this embodiment of the invention;

[0048] Figure 17 The simulation results of active standing waves at the feed ports of the four second intermediate frequency microstrip patch units in this embodiment of the invention;

[0049] Figure 18 The simulation results show the coupling coefficients between the second intermediate frequency microstrip patch unit and all other units in this embodiment of the invention.

[0050] Figure 19 This is a simulation result of the radiation pattern of the four second intermediate frequency microstrip patch units fed in an embodiment of the present invention;

[0051] Figure 20 The following are the axial ratio simulation results for the square feeding of four second intermediate frequency microstrip patch units in this embodiment of the invention;

[0052] In the diagram: 1-High frequency ratio antenna subarray; 11-Low frequency microstrip patch unit; 12-High frequency microstrip patch unit; 2-Low frequency ratio antenna subarray; 21-First intermediate frequency microstrip patch unit; 22-Second intermediate frequency microstrip patch unit; 3-Upper dielectric substrate; 4-Lower dielectric substrate; 5-Through-hole cavity; 6-Feed coaxial; 111-Low frequency feed coaxial; 112-Low frequency rectangular cutout; 113-Circular clearance hole; 114-Lower metal through-hole; 115-Metal shielding through-hole; 121-High frequency feed coaxial; 221-Second intermediate frequency feed coaxial; 122-High frequency rectangular cutout; 222-Second intermediate frequency rectangular cutout; 211-First intermediate frequency feed coaxial; 212-First intermediate frequency rectangular cutout. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. 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.

[0054] This application provides a multi-band common-aperture circularly polarized antenna, which solves the problem that existing common-aperture antennas cannot scientifically and rationally integrate multiple functions, and achieves the goal of low profile, lightweight, low cost, and multi-functional integrated passive antenna array.

[0055] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0056] This application discloses a multi-band common-aperture circularly polarized antenna, comprising: a high-ratio antenna subarray, a low-ratio antenna subarray, an upper dielectric substrate, a lower dielectric substrate, a via cavity, and a coaxial feed. The high-ratio and low-ratio antenna subarrays are distributed on a double-layer dielectric substrate composed of the upper and lower dielectric substrates, and are symmetrical about the center of the double-layer dielectric substrate. The high-ratio antenna subarray includes a low-frequency microstrip patch element and a high-frequency microstrip patch element, with the low-frequency microstrip patch element located on the upper surface of the lower dielectric substrate. The low-frequency microstrip patch unit is located on the upper surface of the upper dielectric substrate; the low-frequency ratio antenna subarray includes four first intermediate-frequency microstrip patch units located on the upper surface of the lower dielectric substrate and four second intermediate-frequency microstrip patch units located on the upper surface of the upper dielectric substrate; the dielectric layer of the lower dielectric substrate is provided with four rectangular metal shielded via cavities, and the metal shielded via cavities are connected to the metal ground of the lower dielectric substrate; the low-frequency microstrip patch unit, the high-frequency microstrip patch unit, the first intermediate-frequency microstrip patch unit, and the second intermediate-frequency microstrip patch unit are directly coaxially fed through a coaxial feeding mechanism. The multi-band common-aperture circularly polarized antenna of this application has a compact overall structure, low profile, simple feeding, easy processing, and flexible selection of operating frequency bands, in order to meet the technical requirements of the new generation of communication and navigation systems for low profile, lightweight, low cost, and multi-functional integrated passive antenna arrays.

[0057] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0058] Example 1:

[0059] Firstly, this invention proposes a multi-band common-aperture circularly polarized antenna, see [link to previous article]. Figure 1-4 It includes:

[0060] High frequency ratio antenna subarray 1, low frequency ratio antenna subarray 2, upper dielectric substrate 3, lower dielectric substrate 4, through-hole cavity 5, and feeding coaxial cable 6;

[0061] The high-frequency ratio antenna subarray 1 and the low-frequency ratio antenna subarray 2 are distributed on a double-layer dielectric substrate composed of an upper dielectric substrate 3 and a lower dielectric substrate 4, and are symmetrical about the center of the double-layer dielectric substrate.

[0062] The high frequency ratio antenna subarray 1 includes a low frequency microstrip patch unit 11 and a high frequency microstrip patch unit 12, wherein the low frequency microstrip patch unit 11 is located on the upper surface of the lower dielectric substrate 4, and the high frequency microstrip patch unit 12 is located on the upper surface of the upper dielectric substrate 3.

[0063] The low-frequency antenna subarray 2 includes four first intermediate frequency microstrip patch units 21 located on the upper surface of the lower dielectric substrate 4 and four second intermediate frequency microstrip patch units 22 located on the upper surface of the upper dielectric substrate 3.

[0064] The dielectric layer of the lower dielectric substrate 4 is provided with four rectangular metal shielding via cavities 5, and the metal shielding via cavities 5 are connected to the metal ground of the lower dielectric substrate 4.

[0065] The low-frequency microstrip patch unit 11, the high-frequency microstrip patch unit 12, the first intermediate-frequency microstrip patch unit 21, and the second intermediate-frequency microstrip patch unit 22 are directly coaxially fed through the power feeding coaxial 6.

[0066] As can be seen, the multi-band common-aperture circularly polarized antenna proposed in this embodiment includes a high-ratio antenna subarray, a low-ratio antenna subarray, an upper dielectric substrate, a lower dielectric substrate, via cavities, and a coaxial feed. The high-ratio and low-ratio antenna subarrays are symmetrically distributed about the center of the dielectric substrate on a double-layer dielectric substrate composed of the upper and lower dielectric substrates. The dielectric layer of the lower dielectric substrate has four rectangular metal-shielded via cavities, which are connected to the metal ground of the lower dielectric substrate. A low-frequency microstrip patch unit and a high-frequency microstrip patch unit constituting the high-ratio antenna subarray, as well as a microstrip patch unit constituting the low-ratio antenna subarray, are all directly coaxially fed. The multi-band common-aperture circularly polarized antenna proposed in this embodiment has a compact structure, low profile, simple feeding, is easy to manufacture, and allows for flexible selection of operating frequency bands.

[0067] The following is in conjunction with the appendix Figure 1-4 The implementation process of an embodiment of the present invention will be described in detail, including explanations of the specific structure and its functions.

[0068] See Figure 1 The multi-band common-aperture circularly polarized antenna proposed in this embodiment includes: a high frequency ratio antenna subarray 1, a low frequency ratio antenna subarray 2, an upper dielectric substrate 3, a lower dielectric substrate 4, a through-hole cavity 5, and a feeding coaxial cable 6.

[0069] Among them, the two types of antenna subarrays, namely the high frequency ratio antenna subarray 1 and the low frequency ratio antenna subarray 2, are arranged in a compact, snowflake-like array and are symmetrically distributed about the array center on the double-layer dielectric substrate composed of the upper dielectric substrate 3 and the lower dielectric substrate 4.

[0070] The upper dielectric substrate 3 is cut into a cross shape, with microstrip patches etched on its upper surface, a dielectric layer in the middle, and all copper plating on its lower surface etched away. The lower dielectric substrate 4 is square, with microstrip patches etched on its upper surface, a dielectric layer in the middle, and a metal ground plane on its lower surface. Four rectangular metal shielded vias 5 are formed in the dielectric layer of the lower dielectric substrate 4, and these vias are connected to the metal ground plane of the lower dielectric substrate 4. Furthermore, all microstrip patches on both the upper and lower dielectric substrates 3 and 4 are coaxially fed directly via a coaxial feed axis 6.

[0071] In this embodiment, both the upper dielectric substrate 3 and the lower dielectric substrate 4 have a dielectric constant ε. r The Rogers Ro4350b is a low-loss RF substrate with a thickness of 3.48 and a single-layer substrate thickness of 1.6 mm.

[0072] See Figure 2-4 The high-frequency ratio antenna subarray 1 includes a low-frequency microstrip patch unit 11 and a high-frequency microstrip patch unit 12. The low-frequency microstrip patch unit 11 is located on the upper surface of the lower dielectric substrate 4, and the high-frequency microstrip patch unit 12 is located on the upper surface of the upper dielectric substrate 3. Specifically, the high-frequency microstrip patch unit 12 is etched from the metal on the upper surface of the upper dielectric substrate 3. Since the high-frequency microstrip patch unit 12 and the low-frequency microstrip patch unit 11 are not on the same layer, there is no obstruction between them. The low-frequency microstrip patch unit 11 and the high-frequency microstrip patch unit 12 are respectively rotated 45° around their own center and positioned in the central region of the array. The low-frequency microstrip patch unit 11 is located at the very center of the array, and a circular clearance hole 113 is opened at the center of the patch to prevent short circuit of the feed coaxial circuit.

[0073] A metal via 114 is provided between the metal ground plane of the lower dielectric substrate 4 and the circular clearance hole 113 of the low-frequency microstrip patch unit 11 to increase the isolation between the stacked patches. The center of the metal via 114 coincides with the center of the inner conductor of the feed coaxial line of the low-frequency microstrip patch unit 11, and is connected vertically to the metal ground plane and the low-frequency microstrip patch unit 11. Due to the position of the metal via 114, the feed point of the high-frequency microstrip patch unit 12 can only be located at the center of the array, so the patch of the high-frequency microstrip patch unit 12 is offset from the center of the array.

[0074] The small frequency ratio antenna subarray 2 includes four first intermediate frequency microstrip patch units 21 located on the upper surface of the lower dielectric substrate 4 and four second intermediate frequency microstrip patch units 22 located on the upper surface of the upper dielectric substrate 3. Moreover, the above-mentioned first intermediate frequency microstrip patch units 21 and second intermediate frequency microstrip patch units 22 are arranged at intervals and interpenetrate with each other. Overall, the four first intermediate frequency microstrip patch units 21, the four second intermediate frequency microstrip patch units 22, and the upper dielectric substrate 3 together present a "rice" shape. Specifically: the four first intermediate frequency microstrip patch units 21 are identical in shape and size, and are symmetrically arranged at the four corners of the array in a counterclockwise rotation of 0°, 90°, 180°, and 270° around the array center, that is, located at the "乂" shape positions of the "rice" character, and the center of each first intermediate frequency microstrip patch unit 21 is located on the diagonal line of the lower dielectric substrate 4. The above four second intermediate frequency microstrip patch units 22 are identical in shape and size, and are symmetrically arranged on the two central axes of the array in a counterclockwise rotation of 0°, 90°, 180°, and 270° around the array center, that is, located at the "十" shape positions of the "rice" character.

[0075] In order to achieve a higher low elevation gain when the beam deflects, the spacing between the co-frequency microstrip antennas should be as small as possible. Considering the limitation of the patch size, finally, the distance between two adjacent first intermediate frequency microstrip patch units 21 is set to d l = 70 mm; the distance between two adjacent second intermediate frequency microstrip patch units 22 is set to d h = 68 mm.

[0076] As Figure 3 and Figure 4 shown, in this embodiment, all the microstrip patch units (including the low-frequency microstrip patch unit 11, the high-frequency microstrip patch unit 12, the first intermediate frequency microstrip patch unit 21, and the second intermediate frequency microstrip patch unit 22) are miniaturized chamfered circular polarization units, and are directly fed by coaxial cables. The feeding points are all located on the central axes of the microstrip patches. The square side length ah of the high-frequency microstrip patch unit 12 is 28.32 mm, and the same-sized incisions are made at the middle positions of the four sides. The length and width of the high-frequency rectangular incision 122 are lh = 5.32 mm and wh = 2.17 mm respectively. The unit realizes circular polarization through chamfering, and the side length qh of the chamfer is 2.24 mm. In order to achieve good matching, the distance th between the high-frequency feeding coaxial cable 121 of the high-frequency microstrip patch unit 12 and the side is 9.42 mm.

[0077] The second intermediate frequency microstrip patch unit 22 has a square side length amh = 32.18 mm. A cutout of the same size is made at the center of each of the four sides. The length and width of the second intermediate frequency rectangular cutout 222 are lmh = 6.48 mm and wmh = 3.41 mm, respectively. The unit achieves circular polarization through chamfering, with a chamfer side length qmh = 3.36 mm. To achieve good matching, the second intermediate frequency feed coaxial cable 221 of the second intermediate frequency microstrip patch unit 22 is positioned at a distance tmh = 11.32 mm from the side.

[0078] The low-frequency microstrip patch unit 11 has a square side length al = 28.32 mm. The four sides have identically sized cutouts at their center. The length and width of the low-frequency rectangular cutout 112 are ll = 3.00 mm and wl = 1.32 mm, respectively. The unit achieves circular polarization through chamfering, with a chamfer side length ql = 3.35 mm. The circular clearance hole 113 at the center of the patch and the metal through-hole 114 below it have the same diameter, both being 3 mm. To achieve good matching, the low-frequency feed coaxial cable 111 of the low-frequency microstrip patch unit 11 is positioned tl = 12.48 mm from the side. The first intermediate-frequency microstrip patch unit 21 has a square side length aml = 33.98 mm. The four sides have identically sized cutouts at their center. The length and width of the first intermediate-frequency rectangular cutout 212 are lml = 7.69 mm and wml = 2.05 mm, respectively. The unit achieves circular polarization through chamfering, with a chamfer side length qml = 2.86 mm. To achieve good matching, the first intermediate frequency (IF) feed coaxial cable 211 of the first IF microstrip patch unit 21 is positioned at a distance tml = 11.27 mm from the side. To improve isolation with the second IF microstrip patch unit 22, a ring of metal shielding vias 115 is provided around the first IF microstrip patch unit 21. These metal shielding vias 115 are located on the lower dielectric substrate 4 and are connected to the metal ground plane. The area of ​​the metal ground plane on the lower dielectric substrate 4 is a × a, where a = 136 mm².

[0079] To verify the performance of the multi-band common-aperture circularly polarized antenna proposed in this invention, we conducted simulation experiments. The simulation results are as follows. Figures 5 to 20 As shown. Wherein:

[0080] Figure 5 The simulation results of the standing wave ratio at the feed port of the low-frequency microstrip patch unit in this embodiment; Figure 6 The simulation results show the coupling coefficients between the low-frequency microstrip patch unit and all other units in the embodiment. Figure 7 The simulation results of the radiation pattern of the low-frequency microstrip patch unit described in this embodiment; Figure 8 The simulation results of the axial ratio of the low-frequency microstrip patch unit in this embodiment; Figure 9 The simulation results of the standing wave ratio at the feed port of the high-frequency microstrip patch unit in this embodiment are shown. Figure 10The simulation results show the coupling coefficients between the high-frequency microstrip patch unit and all other units in this embodiment. Figure 11 The above are simulation results of the radiation pattern of the high-frequency microstrip patch unit described in this embodiment; Figure 12 The simulation results of the axial ratio of the high-frequency microstrip patch unit described in this embodiment; Figure 13 The simulation results of active standing waves at the feed ports of the four first intermediate frequency microstrip patch units described in this embodiment; Figure 14 The simulation results show the coupling coefficients between the first intermediate frequency microstrip patch unit and all other units in this embodiment. Figure 15 This is the simulation result of the radiation pattern of the four first intermediate frequency microstrip patch units fed in this embodiment; Figure 16 The axial ratio simulation results for the square feeding of the four first intermediate frequency microstrip patch units in this embodiment are shown. Figure 17 The simulation results of active standing waves at the feed ports of the four second intermediate frequency microstrip patch units described in this embodiment; Figure 18 This is the simulation result of the coupling coefficient between the second intermediate frequency microstrip patch unit and all other units in this embodiment; Figure 19 The above are the simulation results of the radiation pattern of the four second intermediate frequency microstrip patch units fed in this embodiment; Figure 20 This is the axial ratio simulation result of the four second intermediate frequency microstrip patch units being fed in this embodiment.

[0081] The data in the figure shows that the low-frequency microstrip patch unit 11 operates between 1.61 GHz and 1.64 GHz, with an isolation greater than 18 dB from all surrounding units, radiates left-hand circularly polarized waves in the far field, and has an axial ratio less than 2 dB within a ±60° range; the high-frequency microstrip patch unit 12 operates between 2.47 GHz and 2.52 GHz, with an isolation greater than 30 dB from all surrounding units, radiates right-hand circularly polarized waves in the far field, and has an axial ratio less than 6 dB within a ±60° range; the first intermediate-frequency microstrip patch unit 2... The first intermediate frequency microstrip patch unit 21 operates at 1.98 GHz to 2.02 GHz, with an isolation of greater than 15 dB from all surrounding units. The four first intermediate frequency microstrip patch units 21 radiate left-hand circularly polarized waves in the far field, with an axial ratio of less than 2 dB within a range of ±60°. The second intermediate frequency microstrip patch unit 22 operates at 2.17 GHz to 2.22 GHz, with an isolation of greater than 20 dB from all surrounding units. The four second intermediate frequency microstrip patch units 22 radiate left-hand circularly polarized waves in the far field, with an axial ratio of less than 2 dB within a range of ±60°.

[0082] In summary, compared with existing technologies, it has the following beneficial effects:

[0083] 1. This invention proposes a multi-band common-aperture circularly polarized antenna, comprising a high-ratio antenna subarray, a low-ratio antenna subarray, an upper dielectric substrate, a lower dielectric substrate, via cavities, and a coaxial feed. The high-ratio and low-ratio antenna subarrays are symmetrically distributed about the center of the dielectric substrate on a double-layer dielectric substrate composed of the upper and lower dielectric substrates. The dielectric layer of the lower dielectric substrate has four rectangular metal-shielded via cavities, which are connected to the metal ground of the lower dielectric substrate. A low-frequency microstrip patch unit and a high-frequency microstrip patch unit constituting the high-ratio antenna subarray, and a microstrip patch unit constituting the low-ratio antenna subarray, are all directly coaxially fed. The multi-band common-aperture circularly polarized antenna proposed in this invention has a compact structure, low profile, simple feeding, easy fabrication, and flexible selectable operating frequency bands. It can well meet the technical requirements of next-generation communication and navigation systems for low profile, lightweight, low-cost, and multi-functional integrated passive antenna arrays.

[0084] 2. This invention adopts a novel snowflake-shaped array method to integrate four antennas operating in different frequency bands onto the same aperture surface, realizing high-density aperture reuse. The overall antenna structure is simple and compact, small in size and light in weight, with strong engineering applicability and versatility, and is suitable for mass production.

[0085] 3. This invention introduces a miniaturized circularly polarized microstrip patch antenna, which adopts a simple coaxial direct feeding method, eliminating the complicated feeding network, reducing feeding loss, improving antenna radiation efficiency, and increasing the yield of finished products.

[0086] 4. This invention selects a thin and light double-layer dielectric substrate structure, with the overall antenna thickness not exceeding λ / 30. It has low profile characteristics, small radar cross section, and is easy to integrate between boards, making it suitable for airborne, spaceborne and other platforms with strict requirements for space and integration.

[0087] 5. The present invention introduces a metal via design at the center of the low-frequency microstrip patch unit, which reduces the mutual coupling between the stacked patches without affecting the low-frequency radiation performance; a metal shielding cavity structure is introduced around the first intermediate frequency microstrip patch unit, which improves near-frequency isolation and reduces the design difficulty of the back-end filter.

[0088] 6. The working frequency band of this invention covers high and low frequency bands with large frequency ratios, as well as mid-frequency bands with small frequency ratios. Compared with common aperture arrays with single frequency ratio coverage that are limited by antenna structure, the working frequency band of this antenna is more flexible and selectable, which can adapt to various communication and navigation application scenarios and increase the freedom of front-end radio frequency circuit design.

[0089] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0090] 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 multi-band common-aperture circularly polarized antenna, characterized in that, The multi-band co-aperture circularly polarized antenna includes: a large frequency ratio antenna sub-array (1), a small frequency ratio antenna sub-array (2), an upper dielectric substrate (3), a lower dielectric substrate (4), a through-hole cavity (5), and a feeding coaxial cable (6); wherein, the large frequency ratio antenna sub-array (1) and the small frequency ratio antenna sub-array (2) are distributed on the double-layer dielectric substrate jointly composed of the upper dielectric substrate (3) and the lower dielectric substrate (4), and are centrosymmetric about the center of the double-layer dielectric substrate; the large frequency ratio antenna sub-array (1) includes a low-frequency microstrip patch unit (11) and a high-frequency microstrip patch unit (12), and the low-frequency microstrip patch unit (11) is located on the upper surface of the lower dielectric substrate (4), and the high-frequency microstrip patch unit (12) is located on the upper surface of the upper dielectric substrate (3); the small frequency ratio antenna sub-array (2) includes four first intermediate-frequency microstrip patch units (21) located on the upper surface of the lower dielectric substrate (4) and four second intermediate-frequency microstrip patch units (22) located on the upper surface of the upper dielectric substrate (3); the four first intermediate-frequency microstrip patch units (21) and the four second intermediate-frequency microstrip patch units (22), together with the upper dielectric substrate (3), present a "rice" shape; among them, the four first intermediate-frequency microstrip patch units (21) have the same shape and size, and are symmetrically arranged at the four corners of the array in a counterclockwise rotation of 0°, 90°, 180°, and 270° around the array center, that is, at the "乂" shape positions of the "rice" character, and the center of each first intermediate-frequency microstrip patch unit (21) is located on the diagonal line of the lower dielectric substrate (4); the four second intermediate-frequency microstrip patch units (22) have the same shape and size, and are symmetrically arranged on the two central axes of the array in a counterclockwise rotation of 0°, 90°, 180°, and 270° around the array center, that is, at the "十" shape positions of the "rice" character; the dielectric layer of the lower dielectric substrate (4) is provided with four rectangular metal shielding through-hole cavities (5), and the metal shielding through-hole cavities (5) are connected to the metal ground of the lower dielectric substrate (4); the low-frequency microstrip patch unit (11), the high-frequency microstrip patch unit (12), the first intermediate-frequency microstrip patch unit (21), and the second intermediate-frequency microstrip patch unit (22) are directly coaxially fed through the feeding coaxial cable (6); a circular avoidance hole (113) is opened at the patch center of the low-frequency microstrip patch unit (11); a metal through-hole (114) is arranged in the middle of the circular avoidance hole (113); the low-frequency microstrip patch unit (11), the high-frequency microstrip patch unit (12), the first intermediate-frequency microstrip patch unit (21), and the second intermediate-frequency microstrip patch unit (22) are all miniaturized chamfered circularly polarized units.

2. The multi-band common-aperture circularly polarized antenna as described in claim 1, characterized in that, Both the upper dielectric substrate (3) and the lower dielectric substrate (4) have a dielectric constant. ε r Rogers Ro4350b, a low-loss RF board with a resolution of 3.

48.

3. The multi-band common-aperture circularly polarized antenna as described in claim 1, characterized in that, To achieve good matching, the low-frequency microstrip patch unit (11) is provided with a low-frequency power supply coaxial (111); the first intermediate-frequency microstrip patch unit (21) is provided with a first intermediate-frequency power supply coaxial (211); the second intermediate-frequency microstrip patch unit (22) is provided with a second intermediate-frequency power supply coaxial (221); and the high-frequency microstrip patch unit (12) is provided with a high-frequency power supply coaxial (121).

4. The multi-band common-aperture circularly polarized antenna as described in claim 1, characterized in that, The first intermediate frequency microstrip patch unit (21) is provided with a ring of metal shielding through holes (115) around its perimeter. The metal shielding through holes (115) are located on the lower dielectric substrate (4) and are connected to the metal ground.

5. The multi-band common-aperture circularly polarized antenna as described in claim 3, characterized in that, The low-frequency microstrip patch unit (11), the high-frequency microstrip patch unit (12), the first intermediate-frequency microstrip patch unit (21), and the second intermediate-frequency microstrip patch unit (22) all have the same size cut at the middle position of their four sides, which are respectively the low-frequency rectangular cut (112), the high-frequency rectangular cut (122), the first intermediate-frequency rectangular cut (212), and the second intermediate-frequency rectangular cut (222).

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