Dual-frequency phased-array antenna

Abstract

The invention relates to a dual-frequency phased-array antenna, and belongs to the technical field of phased-array antennas. The dual-frequency phased-array antenna comprises a high-frequency antenna array, a low-frequency antenna unit, dielectric cylinders, a first dielectric layer, a second dielectric layer, a third dielectric layer and a fourth dielectric layer, the first dielectric layer, the second dielectric layer, the third dielectric layer and the fourth dielectric layer are sequentially arranged, the high-frequency antenna array is located above the first dielectric layer, and the first dielectric layer is attached to the lower surface of the high-frequency antenna array; a frequency selective surface is arranged on the second dielectric layer; a wide-angle matching layer is arranged on the third dielectric layer; the low-frequency antenna unit is located below the fourth dielectric layer, and the fourth dielectric layer is attached to the upper surface of the low-frequency antenna unit; the dielectric cylinders are used for supporting the high-frequency antenna array, and the two ends of each dielectric cylinder are connected to the first dielectric layer and the fourth dielectric layer respectively. The invention provides a novel implementation form of the double-frequency phased-array antenna, the requirement of double-frequency broadband wide-angle scanning can be met, and meanwhile, the scanning angle and bandwidth of the antenna are expanded by loading the frequency selective surface and the wide-angle matching layer.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array antennas, and particularly to a dual-band phased array antenna capable of achieving wide-bandwidth and wide-angle scanning in the S-band and X-band, which is applicable to systems that require multi-band collaborative work, such as radar, communication, and electronic warfare. Background Art

[0002] Due to advantages such as fast beam scanning and flexible beam forming, phased array antennas are widely used in modern wireless systems. However, traditional single-band phased array antennas are difficult to meet the requirements of multi-band collaborative work, and the design of multi-band common-aperture phased array antennas faces the following technical challenges: First, the coupling and interference problems caused by a large frequency band interval: The frequency spans of the S-band (2 - 4 GHz) and X-band (8 - 12 GHz) are relatively large, and the near-field coupling and mutual coupling effects between antenna elements are significant, affecting the radiation performance and scanning angle. When traditional dual-band antennas (such as nested or shared-aperture designs) scan at high frequencies, the low-frequency band elements may become parasitic structures, resulting in pattern distortion and gain reduction; Second, impedance mismatch and beam distortion during wide-angle scanning: Existing common-aperture antennas are prone to impedance mismatch and grating lobe problems during wide-bandwidth and wide-angle scanning (such as ±60°) due to the change in the relationship between element spacing and wavelength. Especially in the low-frequency band (S-band), large spacing will cause serious grating lobes in the high-frequency band (X-band), restricting the scanning range; Third, spatial conflicts under a compact layout: Dual-band common-aperture antennas need to integrate two sets of radiation elements or share a radiation structure within a limited space. However, the S-band element size is relatively large, and the X-band elements need to be arranged in the gaps between them, resulting in difficult layout. Existing technologies use multi-layer stacking or special-shaped structures, but this increases the processing complexity and it is difficult to balance the wide-angle scanning performance of both frequency bands.

[0003] The main implementation methods of current dual-band common-aperture antennas include: nested design: The low-frequency elements serve as the support structure for the high-frequency elements, but are blocked by the low-frequency elements during high-frequency scanning; shared radiation patch: Covering dual bands through multi-mode resonance, but the bandwidth is limited and it is difficult to simultaneously meet the wide-band requirements of the S / X bands; frequency selective surface (FSS) assistance: Using FSS to isolate frequency bands, but increasing the profile height, which is not conducive to low-profile design.

[0004] In order to solve the technical problem that it is difficult to achieve wide-bandwidth and wide-angle scanning of multiple frequency bands for the above-mentioned common-aperture phased array antennas due to their compact layout, the present invention proposes a technical solution for a dual-band phased array antenna that operates in the S and X bands and can achieve wide-bandwidth and wide-angle scanning in both frequency bands. Summary of the Invention

[0005] The object of the present invention is to provide a dual - frequency phased - array antenna to solve the problem in the existing phased - array design that it is difficult to achieve wide - bandwidth and wide - angle scanning simultaneously in multiple frequency bands. By using a frequency - selective surface structure and a wide - angle matching layer, the scanning angle and bandwidth are expanded.

[0006] To achieve the above object, the present invention provides the following solutions: The present invention provides a dual - frequency phased - array antenna, including: a high - frequency antenna array, a low - frequency antenna unit, a dielectric column, and a first dielectric layer, a second dielectric layer, a third dielectric layer, and a fourth dielectric layer arranged in sequence; the high - frequency antenna array is located above the first dielectric layer, and the first dielectric layer is attached to the lower surface of the high - frequency antenna array; a frequency - selective surface is provided on the second dielectric layer; a wide - angle matching layer is provided on the third dielectric layer; the low - frequency antenna unit is located below the fourth dielectric layer, and the fourth dielectric layer is attached to the upper surface of the low - frequency antenna unit; the dielectric column is used to support the high - frequency antenna array, and both ends of the dielectric column are respectively connected to the first dielectric layer and the fourth dielectric layer.

[0007] Preferably, the dielectric column passes through the second dielectric layer and the third dielectric layer, there are intervals between the first dielectric layer and the second dielectric layer, and between the second dielectric layer and the third dielectric layer, and the third dielectric layer is connected to the fourth dielectric layer.

[0008] Preferably, the high - frequency antenna array includes high - frequency antenna units arranged in a two - dimensional equidistant manner on the first dielectric layer. The high - frequency antenna unit includes a vertical dielectric layer, a first rectangular metal patch, a patch dipole, a ground metal surface, and a microstrip feeding balun. The first rectangular metal patches are arranged periodically on both side surfaces of the top of the vertical dielectric layer. The patch dipole is printed on one side of the vertical dielectric layer, the microstrip feeding balun is arranged on the other side of the vertical dielectric layer, and the patch dipole is connected to the ground metal surface.

[0009] Preferably, the dual - frequency phased - array antenna further includes a coaxial cable; the low - frequency antenna unit includes a metal body, an air cavity, and a low - frequency feeding microstrip line. The air cavity is arranged inside the metal body. The metal body is provided with a wire - passing hole. The coaxial cable passes through the wire - passing hole. The outer conductor of the coaxial cable is located on the lower surface of the fourth dielectric layer. The inner conductor of the coaxial cable penetrates the fourth dielectric layer and is then connected to the low - frequency feeding microstrip line and is used to feed the low - frequency feeding microstrip line.

[0010] Preferably, the low - frequency feeding microstrip line includes a wide section and a narrow section connected to each other. One end of the narrow section is connected to the inner conductor of the coaxial cable, and a first microstrip stub is provided on the narrow section.

[0011] Preferably, three first microstrip branches are provided, the three first microstrip branches are arranged in parallel, and the middle first microstrip branch is longer than the first microstrip branches on both sides.

[0012] Preferably, the low-frequency antenna unit and the high-frequency antenna array share a common aperture, and the array spacing is less than 0.54λ0, where λ0 is the spatial wavelength corresponding to the highest frequency value of the working frequency band.

[0013] Preferably, the frequency selective surface comprises annular metal sheets arranged in two dimensions with equal spacing, and the annular metal sheets are provided with second microstrip branches.

[0014] Preferably, the second microstrip branch is arranged outside the annular metal sheet, and two second microstrip branches are arranged opposite to each other on one annular metal sheet.

[0015] Preferably, the wide-angle matching layer comprises second rectangular metal patches arranged at equal intervals in one dimension.

[0016] Compared with the prior art, the present invention has achieved the following technical effects: The dual-frequency phased array antenna in the present invention comprises a high-frequency antenna array, a low-frequency antenna unit, a dielectric column, and a first dielectric layer, a second dielectric layer, a third dielectric layer, and a fourth dielectric layer arranged in sequence; the high-frequency antenna array is located above the first dielectric layer, and the first dielectric layer is attached to the lower surface of the high-frequency antenna array; a frequency selective surface is arranged on the second dielectric layer; a wide-angle matching layer is arranged on the third dielectric layer; the low-frequency antenna unit is located below the fourth dielectric layer, and the fourth dielectric layer is attached to the upper surface of the low-frequency antenna unit; the dielectric column is used to support the high-frequency antenna array, and the two ends of the dielectric column are respectively connected to the first dielectric layer and the fourth dielectric layer. The present invention provides a novel dual-frequency phased array antenna structure, which can meet the needs of dual-frequency bandwidth and wide-angle scanning, and at the same time expands the scanning angle and bandwidth of the antenna by loading the frequency selective surface structure and the wide-angle matching layer structure.

[0017] Other technical solutions included in the present invention can also achieve the following technical effects: The present invention feeds by connecting a coaxial line with a low-frequency feeding microstrip line. A first microstrip branch is arranged on the low-frequency feeding microstrip line to filter the feeding signal, thereby effectively increasing the frequency isolation of the dual-frequency phased array antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 Front view of an embodiment of the present invention.

[0020] Figure 2 Side view of an embodiment of the present invention.

[0021] Figure 3 Top view of an embodiment of the present invention.

[0022] Figure 4 Top view of the frequency selective surface of an embodiment of the present invention.

[0023] Figure 5 Top view of the wide-angle matching layer structure of an embodiment of the present invention.

[0024] Figure 6 Top view of the low-frequency microstrip feeder with filtering stubs of an embodiment of the present invention.

[0025] Figure 7 Schematic diagram of the active standing wave ratio of the X-band H-plane scan in an infinite array environment of an embodiment of the present invention.

[0026] Figure 8 Schematic diagram of the active standing wave ratio of the S-band E-plane scan in an infinite array environment of an embodiment of the present invention.

[0027] Figure 9 Schematic diagram of the cross-frequency isolation of the X-band in an infinite array environment of an embodiment of the present invention.

[0028] Figure 10 Schematic diagram of the cross-frequency isolation of the S-band in an infinite array environment of an embodiment of the present invention.

[0029] Wherein, 1. First rectangular metal patch; 2. Vertical dielectric layer; 3. Patch dipole; 4. Microstrip feeding balun; 5. Ground metal plane; 6. High-frequency antenna unit; 7. First dielectric layer; 8. Dielectric column; 9. Frequency selective surface; 10. Second dielectric layer; 11. Wide-angle matching layer; 12. Third dielectric layer; 13. Low-frequency feeding microstrip line; 14. Fourth dielectric layer; 15. Metal body; 16. Coaxial line; 17. Air cavity; 18. High-frequency antenna array; 19. Low-frequency antenna unit; 20. First microstrip stub; 21. Second microstrip stub; 22. Wide section; 23. Narrow section; 24. Ring-shaped metal sheet; 25. Second rectangular metal patch. Detailed implementation manners

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0031] The object of the present invention is to provide a dual-frequency phased array antenna to solve the problems existing in the prior art, which can meet the needs of dual-frequency wide-bandwidth and wide-angle scanning, and utilize the frequency selective surface structure and wide-angle matching layer to expand the scanning angle and bandwidth.

[0032] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Referring to Figures 1 to 6 As shown, the dual-frequency phased array antenna disclosed in the embodiments of the present invention includes: a high-frequency antenna array 18, a low-frequency antenna unit 19, a dielectric column 8, and a first dielectric layer 7, a second dielectric layer 10, a third dielectric layer 12, and a fourth dielectric layer 14 arranged in sequence; the high-frequency antenna array 18 is located above the first dielectric layer 7, and the first dielectric layer 7 is attached to the lower surface of the high-frequency antenna array 18; a frequency selective surface 9 is provided on the second dielectric layer 10; a wide-angle matching layer 11 is provided on the third dielectric layer 12; the low-frequency antenna unit 19 is located below the fourth dielectric layer 14, and the fourth dielectric layer 14 is attached to the upper surface of the low-frequency antenna unit 19; the dielectric column 8 is used to support the high-frequency antenna array 18, and both ends of the dielectric column 8 are respectively connected to the first dielectric layer 7 and the fourth dielectric layer 14. This embodiment provides a new implementation form of the dual-frequency phased array antenna, which can meet the needs of dual-frequency wide-bandwidth and wide-angle scanning, and at the same time expands the scanning angle and bandwidth of the antenna by loading the frequency selective surface 9 and the wide-angle matching layer 11.

[0034] Preferably, the first dielectric layer 7, the second dielectric layer 10, and the third dielectric layer 12 are all made of Rogers RT / duroid5880(tm) dielectric. Rogers RT / duroid5880(tm) is a high-frequency laminate material designed specifically for high-performance radio frequency, microwave, and millimeter-wave applications. The relative dielectric constant of this dielectric is 2.2; the thicknesses of the first dielectric layer 7, the second dielectric layer 10, and the third dielectric layer 12 are all 0.1 mm to 0.3 mm, and preferably 0.2 mm in this embodiment.

[0035] As a preferred embodiment, the dielectric column 8 passes through the second dielectric layer 10 and the third dielectric layer 12, and there are intervals between the first dielectric layer 7 and the second dielectric layer 10, and between the second dielectric layer 10 and the third dielectric layer 12. The third dielectric layer 12 is connected to the fourth dielectric layer 14, and the dielectric column 8 is used to connect the four dielectric layers.

[0036] As a preferred embodiment, the high-frequency antenna array 18 includes high-frequency antenna units 6 arranged in a two-dimensional equidistant manner on the first dielectric layer 7. The high-frequency antenna unit 6 includes a vertical dielectric layer 2, a first rectangular metal patch 1, a patch dipole 3, a ground metal surface 5, and a microstrip feed balun 4. The first rectangular metal patch 1 is periodically arranged on both side surfaces of the top of the vertical dielectric layer 2. The patch dipole 3 is printed on one side of the vertical dielectric layer 2, and the microstrip feed balun 4 is arranged on the other side of the vertical dielectric layer 2. The patch dipole 3 is connected to the ground metal surface 5.

[0037] Preferably, the high-frequency antenna units 6 are distributed in a 2×2 pattern of two rows and two columns on the first dielectric layer 7. The array pitch in the E-plane direction of the high-frequency antenna is 12 mm to 16 mm, preferably 14.87 mm in this embodiment. The array pitch in the H-plane direction is 8 mm to 12 mm, preferably 9.91 mm in this embodiment. The H-plane is a plane parallel to the magnetic field vector (H) radiated by the antenna.

[0038] Preferably, the high-frequency antenna units 6 are distributed in a 3×3 pattern of three rows and three columns on the first dielectric layer 7. The array pitch in the E-plane direction of the high-frequency antenna is 12 mm to 16 mm, preferably 14.87 mm in this embodiment. The array pitch in the H-plane direction is 8 mm to 12 mm, preferably 9.91 mm in this embodiment. The E-plane is a plane parallel to the electric field vector (E) radiated by the antenna.

[0039] Preferably, the high-frequency antenna units 6 are distributed in a 4×4 pattern of four rows and four columns on the first dielectric layer 7. The array pitch in the E-plane direction of the high-frequency antenna is 12 mm to 16 mm, preferably 14.87 mm in this embodiment. The array pitch in the H-plane direction is 8 mm to 12 mm, preferably 9.91 mm in this embodiment.

[0040] As a preferred embodiment, the dual-frequency phased array antenna also includes a coaxial line 16; the low-frequency antenna unit 19 includes a metal body 15, an air cavity 17 and a low-frequency feeding microstrip line 13, the air cavity 17 is arranged inside the metal body 15, the metal body 15 is provided with a threading hole, the threading hole penetrates the metal body 15 in the height direction, the coaxial line 16 passes through the threading hole, the coaxial line 16 includes an inner conductor and an outer conductor, wherein the inner conductor is mainly used to transmit signals, and the outer conductor is mainly used as a shielding layer, the inner conductor and the outer conductor jointly penetrate the threading hole of the metal body 15, the outer conductor is located on the lower surface of the fourth dielectric layer 14, the inner conductor penetrates the fourth dielectric layer 14 and then is connected to the low-frequency feeding microstrip line 13, and is used to feed the low-frequency feeding microstrip line 13, thereby, the coaxial line 16 is connected from the bottom of the metal body 15 to the low-frequency feeding microstrip line 13 on the fourth dielectric layer 14 for feeding.

[0041] As a preferred embodiment, the low-frequency feeding microstrip line 13 includes a wide section 22 and a narrow section 23 connected to each other, one end of the narrow section 23 is connected to the inner conductor of the coaxial line 16, and a first microstrip branch 20 is arranged on the narrow section 23. The first microstrip branch 20 can realize low-pass filtering of the feeding signal, thereby improving the frequency isolation of the phased array antenna by filtering out the high-frequency part of the low-frequency feeding signal.

[0042] Preferably, three first microstrip branches 20 are provided, and the three first microstrip branches 20 are arranged in parallel. The middle first microstrip branch 20 is longer than the first microstrip branches 20 on both sides thereof. The size of the middle first microstrip branch 20 is preferably 9.9 mm×0.5 mm, and the first microstrip branches 20 on both sides have the same length, and the size is preferably 8.3 mm×0.5 mm.

[0043] Preferably, five first microstrip branch nodes 20 are provided, and the five first microstrip branch nodes 20 are arranged in parallel.

[0044] As a preferred implementation, the low-frequency antenna unit 19 and the high-frequency antenna array 18 have the same aperture, and the array spacing is less than 0.54λ0, where λ0 is the spatial wavelength corresponding to the highest frequency value of the working frequency band.

[0045] As a preferred embodiment, the frequency selective surface 9 includes annular metal sheets 24 arranged at equal intervals in two dimensions, and a second microstrip branch 21 is provided on the annular metal sheets 24. The frequency selective surface 9 corresponds one-to-one to the high-frequency antenna unit 6, and the unit spacing is also the same as the high-frequency array spacing. The frequency selective surface 9 reflects the high-frequency electromagnetic waves radiated by the high-frequency antenna through its own frequency selection performance, thereby becoming the theoretical reflection ground of the high-frequency antenna array 18, solving the problem of inconsistent ground height of the high-frequency antenna unit 6 caused by the air cavity 17 of the low-frequency antenna unit 19, effectively promoting the co-aperture fusion of the dual-frequency antenna, and also serving as a matching layer of the low-frequency antenna to expand the scanning bandwidth of the low-frequency antenna.

[0046] Preferably, the annular metal sheets 24 are distributed in a 2×2 pattern of two rows and two columns on the second dielectric layer 10.

[0047] Preferably, the annular metal sheets 24 are distributed in a 3×3 pattern of three rows and three columns on the second dielectric layer 10.

[0048] Preferably, the annular metal sheets 24 are distributed in a 4×4 pattern of four rows and four columns on the second dielectric layer 10.

[0049] As a preferred embodiment, the second microstrip stub 21 is disposed outside the annular metal sheet 24, and two second microstrip stubs 21 are oppositely arranged on one annular metal sheet 24.

[0050] As a preferred embodiment, the wide-angle matching layer 11 includes second rectangular metal patches 25 arranged in a one-dimensional equally spaced manner. This structure can improve the impedance matching during wide-angle scanning of the low-frequency antenna element 19 and broaden the bandwidth of the low-frequency antenna element 19 during large-angle scanning.

[0051] Preferably, the size of the wide-angle matching layer 11 is 5 mm×3 mm, and it is arranged in a one-dimensional equally spaced manner along the E-plane direction of the high-frequency antenna on the third dielectric layer 12, with a spacing of 4 mm to 7 mm, preferably 5.58 mm in this embodiment.

[0052] Active VSWR (Active Voltage Standing Wave Ratio) is a key parameter used to measure the impedance matching performance of active antenna systems (such as phased arrays, multi-antenna MIMO systems) in radio frequency (RF) and microwave systems. In all the above embodiments of the present invention, the operating frequencies of the dual-band phased array antenna are in the S band (2.5 GHz - 4.17 GHz) (50.7%) and the X band (8.02 GHz - 11.1 GHz) (32.2%). It can achieve large-angle scanning within ±60 degrees in the H-plane within the high-frequency operating frequency band range, and all satisfy Active VSWR≤2, as Figure 7 shown. It can achieve large-angle scanning within ±60 degrees in the E-plane within the low-frequency operating frequency band range, and all satisfy Active VSWR≤3. When scanning within ±45 degrees in the E-plane, it can achieve Active VSWR≤2, as Figure 8 shown. As Figure 9 shown, by loading microstrip stubs on the low-frequency feeding microstrip line 13, the function of low-pass filtering can be achieved, improving the isolation between different frequencies of the high- and low-frequency units in the high-frequency band, such that the isolation between different frequencies within the high-frequency operating frequency band is above 25 dB. At the same time, the isolation between different frequencies of the high- and low-frequency units in the low-frequency band is also above 20 dB, as Figure 10 shown.

[0053] In the present invention, specific examples are used to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A dual-frequency phased array antenna, characterized in that, Comprising: a high-frequency antenna array (18), a low-frequency antenna unit (19), a dielectric column (8), and a first dielectric layer (7), a second dielectric layer (10), a third dielectric layer (12), and a fourth dielectric layer (14) arranged in sequence; the high-frequency antenna array (18) is located above the first dielectric layer (7), and the first dielectric layer (7) is attached to the lower surface of the high-frequency antenna array (18); a frequency selective surface (9) is provided on the second dielectric layer (10); a wide-angle matching layer (11) is provided on the third dielectric layer (12); the low-frequency antenna unit (19) is located below the fourth dielectric layer (14), and the fourth dielectric layer (14) is attached to the upper surface of the low-frequency antenna unit (19); the dielectric column (8) is used to support the high-frequency antenna array (18), and both ends of the dielectric column (8) are respectively connected to the first dielectric layer (7) and the fourth dielectric layer (14).

2. The dual-band phased array antenna according to claim 1, wherein the dielectric column (8) passes through the second dielectric layer (10) and the third dielectric layer (12), there are intervals between the first dielectric layer (7) and the second dielectric layer (10), and between the second dielectric layer (10) and the third dielectric layer (12), and the third dielectric layer (12) is connected to the fourth dielectric layer (14).

3. The dual-band phased array antenna according to claim 1, wherein the high-frequency antenna array (18) includes high-frequency antenna units (6) arranged in a two-dimensional equidistant manner on the first dielectric layer (7), the high-frequency antenna unit (6) includes a vertical dielectric layer (2), a first rectangular metal patch (1), a patch dipole (3), a ground metal plane (5), and a microstrip feed balun (4), the first rectangular metal patch (1) is periodically arranged on both side surfaces of the top of the vertical dielectric layer (2), the patch dipole (3) is printed on one side of the vertical dielectric layer (2), the microstrip feed balun (4) is arranged on the other side of the vertical dielectric layer (2), and the patch dipole (3) is connected to the ground metal plane (5).

4. The dual-frequency phased array antenna according to claim 1, characterized in that, It further includes a coaxial cable (16); the low-frequency antenna unit (19) includes a metal body (15), an air cavity (17), and a low-frequency feed microstrip line (13), the air cavity (17) is arranged inside the metal body (15), the metal body (15) is provided with a wire passing hole, the coaxial cable (16) passes through the wire passing hole, the outer conductor of the coaxial cable (16) is located on the lower surface of the fourth dielectric layer (14), and the inner conductor of the coaxial cable (16) penetrates through the fourth dielectric layer (14) and is connected to the low-frequency feed microstrip line (13) and is used to feed the low-frequency feed microstrip line (13).

5. The dual-frequency phased array antenna according to claim 4, wherein the low-frequency feed microstrip line (13) includes a wide section (22) and a narrow section (23) connected to each other, one end of the narrow section (23) is connected to the inner conductor of the coaxial cable (16), and a first microstrip stub (20) is provided on the narrow section (23).

6. The dual-frequency phased array antenna according to claim 5, characterized in that Three first microstrip branches (20) are provided, the three first microstrip branches (20) are arranged in parallel, and the middle first microstrip branch (20) is longer than the first microstrip branches (20) on both sides thereof.

7. The dual-band phased array antenna according to claim 1, wherein, The low-frequency antenna unit (19) and the high-frequency antenna array (18) share a common aperture, and the array spacing is less than 0.54λ0, where λ0 is the spatial wavelength corresponding to the highest frequency value of the working frequency band.

8. The dual-band phased array antenna according to claim 1, characterized in that, The frequency selective surface (9) comprises annular metal sheets (24) arranged at equal intervals in two dimensions, and a second microstrip branch (21) is provided on the annular metal sheet (24).

9. The dual-band phased array antenna according to claim 8, wherein The second microstrip branch node (21) is arranged outside the annular metal sheet (24), and two second microstrip branch nodes (21) are arranged opposite to each other on one annular metal sheet (24).

10. The dual-band phased array antenna according to claim 1, wherein The wide-angle matching layer (11) comprises second rectangular metal patches (25) arranged at equal intervals in one dimension.

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