Low-scattering ultra-wideband wide-angle scanning antenna array

Abstract

The invention discloses a low-scattering ultra-wideband wide-angle scanning antenna array, and belongs to the technical field of antennas. The antenna comprises an ultrathin wide-angle impedance matching layer and an antenna array. The antenna array comprises four antenna sub-arrays, and the antenna sub-arrays are arranged in a 2 * 2 chessboard mode; the antenna sub-array is composed of unit antennas arranged in a 8 * 8 rectangle. Wherein the unit antennas of two antenna sub-arrays are first ultra-wideband antenna units, and the unit antennas of the other two antenna sub-arrays are second ultra-wideband antenna units. The antenna array is low in profile, the VSWR can be kept to be smaller than 3.5 in the working frequency band of 2.5-18 GHz to meet the good radiation state, + / -72-degree large-angle beam scanning is supported, meanwhile, RCS reduction with the average being 8.7 dB and the peak value being 13.9 dB is achieved, and the array antenna design integrating the low profile, the wide frequency band, the wide angle and RCS reduction is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and specifically relates to a low-scattering ultra-wide bandwidth angular scanning antenna array, which is suitable for scenarios such as stealth aircraft, multi-band radar systems and wide-angle electronic countermeasures, and can achieve low radar scattering cross section (RCS) and large-angle beam scanning within an ultra-wide frequency band. Background Art

[0002] With the rapid development of modern radar and communication systems, array antenna technology has been widely used in airborne phased arrays, shipborne early warning radars, and ground-based multiple-input multiple-output (MIMO) systems from the X-band to the Ka-band due to its beamforming capabilities and spatial scanning characteristics. However, in military applications, the high gain characteristics of traditional array antennas and the strong electromagnetic scattering characteristics caused by metal structures form a sharp contradiction. According to physical optics theory, the radar cross section (RCS) of a typical airborne array antenna can reach 10m in the S-band. 2 The magnitude of the attack seriously restricts the stealth survivability of weapons and equipment.

[0003] Currently, there are two major technical routes in the field of low RCS antenna design in the international academic community: the first is based on new electromagnetic materials such as fractal structures and artificial magnetic conductors (AMCs). Although it can achieve an RCS reduction of about 10dB in the 2-18GHz frequency band, it generally leads to a 30%-50% increase in the antenna profile and the beam scanning range is limited to ±45 degrees; the second is the use of frequency selective surface (FSS) or polarization conversion metasurface technology. Although it can maintain the antenna radiation efficiency, it is limited by narrowband characteristics (relative bandwidth <20%) and angle sensitivity (performance deteriorates sharply when the incident angle is >30°).

[0004] The design of a low-scattering, ultra-wideband, wide-angle scanning antenna can reduce the risk of target detection and strike in an increasingly complex and diverse electromagnetic environment, increase functional diversity, and thus improve the stealth performance and communication quality of combat weapons and equipment. While maintaining wide-angle scanning and ultra-wideband radiation performance, it achieves full-band, wide-angle RCS suppression, possessing significant military and civilian applications.

[0005] The Chinese patent application with application number 202411292833.X and invention name “Low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure” discloses an antenna that achieves broadband RCS reduction of FP antenna through AMC structure, but the entire cross-section structure is high, and its reflection coefficient is less than -10dB and has a narrow range (10.1~10.9GHz), which is only 1.08:1; the Chinese patent application with application number CN202310849882.8 and invention name “A kind of ultra-wide-angle beam scanning ultra-wideband low RCS metal waveguide phased array antenna” discloses a phased array antenna, which achieves RCS reduction by integrating several unequal height all-metal rectangular waveguide units in an array arrangement based on phase cancellation technology, but its scanning angle in the H plane is only ±35 degrees; the prior art “Radar Cross Section Reduction of Wideband Vivaldi Antenna Arrays With Array-Level Scattering Cancellation” discloses a broadband phased array antenna with array-level scattering cancellation, which achieves in-band RCS reduction, but its relative bandwidth is only 40% and the profile height is about 1.1λ low , and the scanning angle reaches ±60 degrees only at 10GHz. As the demand for multifunctional antennas on stealth platforms becomes increasingly urgent, an array antenna design that combines low profile, wide frequency band, wide angle, and RCS reduction while taking into account radiation performance is urgently needed. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a low-scattering ultra-wide bandwidth angular scanning antenna array. The cross-sectional height of the antenna array is only 0.1833λ low It can maintain VSWR < 3.5 in the operating frequency band of 2.5-18GHz (relative bandwidth 151.22%) to meet good radiation conditions, support ±72 degrees (18GHz) large-angle beam scanning, and achieve an average RCS reduction of 8.7dB and a peak of 13.9dB (average RCS reduction value of 3.5GHz-17GHz: 9.35dB), realizing an array antenna design that integrates low profile, wide frequency band, wide angle and RCS reduction.

[0007] The solution adopted by the present invention for the proposed technical problem is:

[0008] A low-scattering, ultra-wide-bandwidth angular scanning antenna array comprises an ultra-thin, wide-angle impedance matching layer 1 and an antenna array; the antenna array comprises four antenna subarrays arranged in a 2×2 checkerboard pattern; the antenna subarrays are composed of unit antennas arranged in an 8×8 rectangular pattern; the unit antennas of two antenna subarrays are first ultra-wideband antenna units, and the unit antennas of the other two antenna subarrays are second ultra-wideband antenna units;

[0009] The first ultra-wideband antenna unit includes a radiating patch 5, a dielectric substrate 4, a tapered microstrip branch-fed balun 3, a metal floor 2, and an RF coaxial connector. The radiating patch 5 and the tapered microstrip branch-fed balun 3 are respectively located on the front and rear surfaces of the dielectric substrate 4. The radiating patch 5 is symmetrical about the longitudinal axis and has a trumpet-shaped opening slot etched on the basis of the dielectric substrate 4. The metal floor 4 is placed perpendicular to the bottom of the dielectric substrate 4. The outer conductor of the RF coaxial connector is connected to the radiating patch 5, and the inner core is connected to the tapered microstrip direct-fed balun 3.

[0010] The second ultra-wideband antenna unit has the same structure as the first ultra-wideband antenna unit, but has a different size from the first ultra-wideband antenna unit in terms of the size of the horn-shaped opening slot;

[0011] The ultra-thin wide-angle impedance matching layer 1 is located at the upper end of the antenna array, and includes a matching layer dielectric substrate and a metal patch; the metal patch is rectangular and located on the upper surface of the matching layer dielectric substrate.

[0012] Furthermore, the horn-shaped opening slot includes a circular slot, a rectangular slot and an exponential gradient opening slot connected in sequence from bottom to top. The circular slot line plays a matching impedance role for the gradient microstrip branch feeding balun. The width of the opening slot gradually expands from the feeding point to the opening point, realizing a slow impedance transformation.

[0013] Furthermore, in the trumpet-shaped opening groove etched on the radiation patch 5, the exponentially tapered opening groove is composed of a first tapered groove line and a second tapered groove line. A rectangular coordinate system is established with the left bottom corner of the yoz plane where the dielectric substrate 4 is located as the origin. The function equation satisfied by the first tapered groove line is:

[0014] y=c1e αz +c2

[0015] Where y and z represent the y-axis coordinate variable and the z-axis coordinate variable, respectively; α is the curvature of the curve, α = 0.155; the starting point coordinates of the first gradient groove line are the end points of the rectangular groove; c1 and c2 are two constants; the second gradient groove line is symmetrical to the first gradient groove line, and together they form an exponential gradient opening groove shape.

[0016] Furthermore, the antenna subarray is arranged in two dimensions, and two adjacent unit antennas are closely arranged in the plane direction where the radiation patch is located, and the unit antenna period in the other direction is about 0.45λhigh ,λ high The wavelength corresponding to the highest frequency in the working bandwidth.

[0017] Furthermore, the length of the rectangular slot in the radiation patch 5 is greater than that of the first ultra-wideband antenna unit.

[0018] Furthermore, for each unit antenna, the metal patches in the ultra-thin wide-angle impedance matching layer 1 are arranged in a 9×9 rectangular shape, and the size of the metal patches is 0.026λ. high *0.024λ high ,λ high The wavelength corresponding to the highest frequency in the working bandwidth.

[0019] The beneficial effects of the present invention are:

[0020] The array antenna of the present invention achieves coordinated optimization of ultra-wideband performance and wide-angle scanning while retaining low scattering characteristics;

[0021] The present invention achieves VSWR < 3.5 in an ultra-wide frequency band of 2.5-18 GHz (relative bandwidth 151.22%), breaking through the bandwidth limitation of traditional tightly coupled arrays (typical values of 6-18 GHz in the literature) and significantly expanding the applicability of low-frequency bands (S / C bands).

[0022] The present invention supports wide-angle beam scanning of ±72° (18GHz), has excellent impedance stability during scanning, and maintains VSWR < 3.5 during full-band scanning, solving the impedance mismatch problem in traditional array scanning.

[0023] While ensuring wide-angle scanning and impedance matching, the present invention achieves an average RCS reduction of 8.7dB and a peak of 13.9dB (average RCS reduction value from 3.5GHz to 17GHz: 9.35dB), which is suitable for the multi-functional requirements of stealth platforms.

[0024] The present invention realizes a miniaturized and highly integrated design; the antenna unit size is compressed to 0.063λ×0.183λ (λ is the wavelength of the lowest operating frequency), is easy to process, has a simple structure, and is suitable for space-constrained platforms (such as drones and microsatellites). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the three-dimensional structure of the antenna array of the present invention;

[0026] Figure 2 Schematic diagram of the structure of the first ultra-wideband antenna unit in the antenna array of the present invention;

[0027] Figure 3 Schematic diagram of the structure of the second ultra-wideband antenna unit in the antenna array of the present invention;

[0028] Figure 4 Schematic diagram of the upper surface structure of the ultra-thin wide-angle impedance matching layer corresponding to the ultra-wideband antenna unit in the antenna array of the present invention;

[0029] Figure 5 is a graph showing the active standing wave ratio of the central unit of the antenna array subarray described in the embodiment;

[0030] Figure 6 The E-plane scanning pattern of the array antenna at different frequencies and different scanning angles described in the embodiment, wherein (a) is the E-plane scanning pattern of the antenna array at 2.5 GHz when the scanning angles are 0 degrees, ±30 degrees, and the maximum scanning angle; (b) is the E-plane scanning pattern of the antenna array at 10 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle; (c) is the E-plane scanning pattern of the antenna array at 18 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle;

[0031] Figure 7 The H-plane scanning pattern of the array antenna at different frequencies and different scanning angles described in the embodiment, wherein (a) is the H-plane scanning pattern of the antenna array at 2.5 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle, (b) is the H-plane scanning pattern of the antenna array at 10 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle, and (c) is the H-plane scanning pattern of the antenna array at 18 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle;

[0032] Figure 8 Graph showing RCS comparisons of the antenna array described in the embodiment, the PEC of equal size, and the reference antenna array. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and examples.

[0034] This embodiment provides a low-scattering ultra-wide bandwidth angular scanning antenna array, such as Figure 1 As shown, it includes an ultra-thin wide-angle impedance matching layer 1 and an antenna array; the antenna array includes four antenna sub-arrays, and the antenna sub-arrays are arranged in a 2×2 checkerboard pattern; the antenna sub-arrays are composed of unit antennas arranged in an 8×8 rectangular pattern; the unit antennas of two antenna sub-arrays are first ultra-wideband antenna units, and the unit antennas of the other two antenna sub-arrays are second ultra-wideband antenna units.

[0035] like Figure 2As shown, the first ultra-wideband antenna unit includes a radiating patch 5, a dielectric substrate 4, a gradient microstrip branch feeding balun 3, a metal floor 2 and an RF coaxial connector; the radiating patch 5 and the gradient microstrip branch feeding balun 3 are respectively located on the front and back surfaces of the dielectric substrate 4; the radiating patch 5 is symmetrical about the longitudinal axis, and on the basis of fully covering the dielectric substrate 4, a horn-shaped opening slot is etched, and the horn-shaped opening slot includes a circular slot, a rectangular slot and an exponential gradient opening slot connected in sequence from bottom to top, and the circular slot line plays a matching impedance role for the feeding balun. The width of the opening slot gradually expands from the feeding point to the opening point, realizing a slow impedance transformation, so that the bandwidth of the ultra-wideband antenna unit reaches 7.2:1, and the reflection coefficient of the antenna unit in the ultra-wideband is less than -10dB; the metal floor 4 is placed perpendicular to the bottom of the dielectric substrate 4, the outer conductor of the RF coaxial connector is connected to the radiating patch 5, and the inner core is connected to the gradient microstrip direct feeding balun 3.

[0036] like Figure 3 As shown, the second ultra-wideband antenna unit has the same structure as the first ultra-wideband antenna unit, and the length of the rectangular slot in the radiation patch 5 is greater than that of the first ultra-wideband antenna unit. In this embodiment, the size of the rectangular slot in the first ultra-wideband antenna unit is 0.02λ high *0.2λ high , the size of the rectangular slot in the second ultra-wideband antenna unit is 0.02λ high *0.3λ high ,λ high The wavelength corresponding to the highest frequency in the working bandwidth.

[0037] The second type of ultra-wideband antenna unit has a similar overall structure to the first type, differing only in the size and shape of the radiating patch. Its reflected phase remains opposite to that of the first type of ultra-wideband antenna unit within the band, achieving the prerequisite for achieving chessboard phase cancellation in a low-scattering ultra-wideband angular scanning antenna array.

[0038] The ultra-thin wide-angle impedance matching layer 1 is located at the upper end of the antenna array, and includes a matching layer dielectric substrate and a metal patch. The metal patch is rectangular and located on the upper surface of the matching layer dielectric substrate. For each unit antenna, the metal patch is arranged in a 9×9 rectangular pattern, as shown in FIG. Figure 4 In this embodiment, the size of the rectangular metal patch is 0.026λ high *0.024λ high The ultra-thin wide-angle impedance matching layer 1 is used to improve the radiation performance of the array antenna.

[0039] The antenna subarray is arranged in two dimensions. The adjacent two unit antennas are closely arranged in the plane direction where the radiation patch is located. The unit antenna period in the other direction is about 0.45λ. high .

[0040] In the trumpet-shaped opening groove etched on the radiation patch 5, the exponentially tapered opening groove is composed of a first tapered groove line and a second tapered groove line. A rectangular coordinate system is established with the left bottom corner of the dielectric substrate 4 on the yoz plane as the origin. The function equation satisfied by the first tapered groove line is:

[0041] y=c1e αz +c2

[0042] Where y and z represent the y-axis and z-axis coordinate variables, respectively; α is the curvature of the curve, which in this embodiment is 0.155; and c1 and c2 are two constants. In this embodiment, the starting point coordinates of the first gradient groove are the end positions of the rectangular groove, and c1 and c2 are 0.42 and -0.48, respectively.

[0043] The second gradient groove line is symmetrical to the first gradient groove line, and together form the shape of an exponential gradient opening groove.

[0044] In the antenna described in this embodiment, the two tapered slots provide a smooth impedance gradient. When a high-frequency signal is input through the feed structure, electromagnetic waves propagate along the tapered slots. As the slot width gradually increases, the propagation speed and wave impedance of the electromagnetic waves also change, forming traveling wave propagation. During propagation, the traveling wave gradually radiates energy outward rather than reflecting at the terminal (low reflection coefficient), thus achieving broadband characteristics.

[0045] The antenna described in this embodiment uses a segmented composite tapered slot line to restrict the flow direction of the current, so that the two ultra-wideband antennas present opposite phase differences, thereby achieving low scattering characteristics.

[0046] In this embodiment, the operating frequency band of the antenna array is 2.5-18 GHz. The dielectric substrate 4 of the two ultra-wideband antenna units is made of Wangling TP440, with a relative dielectric constant of 4.4, a width w of 7.54 mm, a thickness of 0.6 mm, and a height h of 21.73 mm; the dimensions of the ultra-thin wide-angle impedance matching layer are 120.64 mm long and 116.8 mm wide, and the dielectric substrate is made of Rogers3003G2 dielectric sheet material, and the metal patches on its upper surface are placed at a spacing of 0.45 mm.

[0047] Figure 5 The active standing wave ratio curve of the central unit of the antenna array sub-array of this embodiment is shown in FIG. It can be seen that the antenna array of this embodiment maintains good impedance matching performance within 2.5-18 GHz.

[0048] Figure 6 is the E-plane scanning pattern of the array antenna of this embodiment at different frequencies and different scanning angles, where: Figure 6 (a) is the E-plane scanning pattern of the antenna array at 2.5GHz when the scanning angle is 0 degree, ±30 degrees and the maximum scanning angle. Figure 6 (b) is the E-plane scanning pattern of the antenna array at 10 GHz when the scanning angle is 0 degrees, ±45 degrees and the maximum scanning angle. Figure 6 (c) is the E-plane scanning pattern of the antenna array at 18 GHz when the scanning angles are 0 degrees, ±45 degrees, and the maximum scanning angle.

[0049] Figure 7 is the H-plane scanning pattern of the array antenna of this embodiment at different frequencies and different scanning angles, where: Figure 7 (a) is the H-plane scanning pattern of the antenna array at 2.5GHz when the scanning angle is 0 degree, ±45 degrees and the maximum scanning angle. Figure 7 (b) is the H-plane scanning pattern of the antenna array at 10 GHz when the scanning angle is 0 degrees, ±45 degrees, and the maximum scanning angle. Figure 7 (c) shows the H-plane scanning pattern of the antenna array at 18 GHz with scan angles of 0 degrees, ±45 degrees, and the maximum scan angle. It can be seen that the beam of the antenna array of this embodiment has a maximum H-plane scanning angle of 67 degrees at 10 GHz and a maximum H-plane scanning angle of 74 degrees at 18 GHz.

[0050] Figure 8 The following graph compares the RCS of the antenna array of this embodiment, an equivalent-sized PEC, and a reference antenna array. The reference antenna array is composed of Type 1 ultra-wideband antenna elements and has the same caliber and scale as the designed antenna array. As can be seen, the antenna array of this embodiment maintains an RCS reduction of >6dB across the 3.5GHz-17GHz range, achieving an average RCS reduction of 8.7dB and a peak RCS reduction of 13.9dB.

[0051] The present invention provides a basis for the integrated radiation and scattering work of an antenna array and can be applied to the fields of wireless communication and in-band stealth of array antennas.

[0052] In summary, the present invention discloses a low-scattering, ultra-wide-bandwidth angular scanning antenna array. Through a checkerboard array arrangement, wide-angle scanning can be achieved across the entire band while maintaining extremely low scattering.

Claims

1. A low-scattering ultra-wide bandwidth angular scanning antenna array, characterized in that: The invention comprises an ultra-thin wide-angle impedance matching layer (1) and an antenna array; the antenna array comprises four antenna sub-arrays, and the antenna sub-arrays are arranged in a 2×2 chessboard pattern; the antenna sub-arrays are composed of unit antennas arranged in an 8×8 rectangular pattern; the unit antennas of two antenna sub-arrays are first ultra-wideband antenna units, and the unit antennas of the other two antenna sub-arrays are second ultra-wideband antenna units; The first ultra-wideband antenna unit comprises a radiation patch (5), a dielectric substrate (4), a gradient microstrip branch feeding balun (3), a metal floor (2) and a radio frequency coaxial connector; the radiation patch (5) and the gradient microstrip branch feeding balun (3) are respectively located on the front and rear surfaces of the dielectric substrate (4); the radiation patch (5) is symmetrical about the longitudinal axis, and a horn-shaped opening groove is etched on the basis of the dielectric substrate (4) that is fully covered; The metal floor (2) is placed perpendicular to the bottom of the dielectric substrate (4), the outer conductor of the radio frequency coaxial connector is connected to the radiation patch (5), and the inner core is connected to the gradient microstrip direct-feed balun (3); The second ultra-wideband antenna unit has the same structure as the first ultra-wideband antenna unit, but has a different size from the first ultra-wideband antenna unit in terms of the size of the horn-shaped opening slot; The ultra-thin wide-angle impedance matching layer (1) is located at the upper end of the antenna array and comprises a matching layer dielectric substrate and a metal patch; the metal patch is rectangular and is located on the upper surface of the matching layer dielectric substrate.

2. The low-scattering ultra-wide bandwidth angular scanning antenna array according to claim 1, characterized in that: The horn-shaped opening slot includes a circular slot, a rectangular slot and an exponential gradient opening slot connected in sequence from bottom to top. The circular slot line plays a matching impedance role for the gradient microstrip branch feeding balun (3). The width of the opening slot gradually expands from the feeding position to the opening position, thereby realizing a slow impedance transformation.

3. The low-scattering ultra-wide bandwidth angular scanning antenna array according to claim 2, characterized in that: In the trumpet-shaped opening groove etched on the radiation patch (5), the exponentially gradient opening groove is composed of a first gradient groove line and a second gradient groove line. A rectangular coordinate system is established with the left bottom corner on the yoz plane where the dielectric substrate (4) is located as the origin. The function equation satisfied by the first gradient groove line is: Where y and z represent the y-axis coordinate variable and the z-axis coordinate variable, respectively; α is the curvature of the curve, α = 0.155; the starting point coordinates of the first gradient groove line are the end points of the rectangular groove; c1 and c2 are two constants; the second gradient groove line is symmetrical to the first gradient groove line, and together they form an exponential gradient opening groove shape.

4. The low-scattering ultra-wide bandwidth angular scanning antenna array according to claim 1, characterized in that: The antenna subarray is arranged in two dimensions. The adjacent two unit antennas are closely arranged in the plane direction where the radiation patch is located. The unit antenna period in the other direction is about 0.45λ. high ,λ high The wavelength corresponding to the highest frequency in the working bandwidth.

5. The low-scattering ultra-wide bandwidth angular scanning antenna array according to claim 2, characterized in that: The length of the rectangular slot in the radiation patch (5) is greater than that of the first ultra-wideband antenna unit.

6. The low-scattering ultra-wide bandwidth angular scanning antenna array according to claim 1, characterized in that: For each unit antenna, the metal patches in the ultra-thin wide-angle impedance matching layer (1) are arranged in a 9×9 rectangular pattern, and the size of the metal patches is 0.026λ. high *0.024λ high ,λ high The wavelength corresponding to the highest frequency in the working bandwidth.

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