Radiation and scattering integrated design radial line slot array antenna for realizing dual-band RCS (Radar Cross Section) reduction

Abstract

The invention discloses a radial line slot array antenna for realizing dual-band RCS (radar cross section) reduction through radiation and scattering integrated design. The radial line slot array antenna comprises an upper-layer dual-band spiral geometric phase metasurface and a lower-layer radial line slot array antenna, the upper spiral geometric phase metasurface comprises a dielectric substrate and a double-end arrow metal pattern array which is etched on the dielectric substrate and is spirally arranged; the lower-layer radial line slot array antenna comprises a single-layer radial line waveguide, a herringbone slot pair array which is loaded on the upper surface of the waveguide and is spirally arranged, a short-circuit coaxial feed probe and an annular slot; and an air gap exists between the upper-layer double-frequency spiral geometric phase metasurface and the lower-layer radial line slot array antenna. The geometric phase metasurface is simple in structure and low in profile, has dual-band and broadband working performance, is combined with the RLSA to perform radiation-scattering integrated design, and realizes dual-band RCS reduction at two ends of a radiation band while obtaining high-gain circularly polarized radiation of the RLSA.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna stealth, and in particular relates to a radial line slot array antenna with an integrated radiation and scattering design to achieve dual-band RCS reduction. Background Art

[0002] In modern military systems, multi-band, broadband radar stealth is an important requirement for many weapon platforms. At the same time, in order to achieve high-sensitivity detection, high-gain and high-efficiency antennas are widely used. These large-aperture high-gain antennas are usually the main scattering sources in low-scattering weapon platforms, and the application of radar stealth technology to them often has a serious impact on the antenna radiation performance. Therefore, the design of multi-band, broadband RCS-reduced high-gain antennas has many difficulties and is also of great significance.

[0003] The radial line slot array antenna (RLSA) is a special waveguide slot array antenna with high gain and high efficiency. It realizes circularly polarized or linearly polarized radiation by opening a rotating slot pair on the radial waveguide, and has the advantages of low profile and planar structure. Its transmission mode based on the radial line waveguide makes the conductor loss very small and has high radiation efficiency; and based on the characteristics of traveling wave mode excitation radiation, it is easy to achieve large aperture, high gain, and high aperture efficiency. Although RLSA has many attractive radiation characteristics, there are few studies on its RCS reduction. The dense and spiral arrangement of RLSA radiation slots makes it easier for common low-scattering technology to affect its radiation performance, making it more complicated to design.

[0004] In recent years, phase-modulated electromagnetic metasurfaces have been widely studied and applied in the field of antenna stealth. Loading a phase-modulated metasurface can change the scattering field of the antenna to achieve RCS reduction, but due to the impact on the amplitude and phase distribution of the antenna radiation aperture field, it often deteriorates its radiation performance. The geometric phase metasurface is a unique phase-modulated metasurface that can obtain the desired phase difference by rotating its anisotropic resonant structure. The characteristics of this geometric rotation phase modulation provide the possibility of maintaining the radiation performance of RLSA while achieving RCS reduction. In addition, the design of dual-band and broadband operation of the geometric phase metasurface also has important application value. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction.

[0006] The technical solution to realize the present invention is: a radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction, comprising an upper dual-band spiral geometric phase metasurface and a lower radial line slot array antenna;

[0007] The upper spiral geometric phase metasurface includes a dielectric substrate and a spirally arranged double-headed arrow metal pattern array etched thereon; the double-headed arrow metal pattern includes arrow patterns with two ends symmetrical about the origin and a bent metal wire connected in the middle;

[0008] The lower layer radial line slot array antenna comprises a single layer radial line waveguide filled with dielectric, a herringbone slot pair array loaded on the upper surface of the waveguide and arranged in a spiral manner, a short-circuit coaxial feeding probe penetrating the waveguide, and an annular slot introduced at the center of the top of the waveguide;

[0009] There is an air gap between the upper dual-frequency spiral geometric phase metasurface and the lower radial line slot array antenna.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] (1) The present invention provides a geometric phase metasurface with a simple structure and a low profile, which has the performance of dual-band and broadband operation, and can achieve dual-band RCS reduction at both ends of the RLSA radiation band, and has important practical value;

[0012] (2) The geometric phase metasurface provided by the present invention adopts the same spiral arrangement as the radial line slot array antenna, forming a phase distribution similar to a vortex beam with a mode number of ±2, and has good single-station RCS reduction capability;

[0013] (3) The present invention realizes an integrated design of radiation scattering, miniaturizing the geometric phase unit and combining it with the "human" shaped gap for an integrated design. Based on the original spiral arrangement of RLSA and the aperture field distribution control, high-gain and high-efficiency left-hand circularly polarized (LHCP) radiation is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 It is a three-dimensional structure diagram of the antenna proposed in the embodiment of the present invention.

[0016] Figure 2 A top view of the dual-frequency spiral geometric phase metasurface on the antenna proposed in an embodiment of the present invention.

[0017] Figure 3 FIG. 4 is a top view of the lower radial line slot array according to an embodiment of the present invention.

[0018] Figure 4 Schematic diagram and top view of the three-dimensional structure of the dual-frequency geometric phase unit according to an embodiment of the present invention.

[0019] Figure 5 It is a three-dimensional structural diagram of the radiation scattering integrated unit according to an embodiment of the present invention.

[0020] Figure 6 It is a graph showing the co-polarization and cross-polarization reflection coefficients of the dual-frequency geometric phase unit according to an embodiment of the present invention when illuminated by a circularly polarized wave.

[0021] Figure 7 is the axial ratio and normalized radiation power P of the radiation scattering integrated unit of the embodiment of the present invention rad Graph as a function of the gap length l.

[0022] Figure 8 This is a graph showing how the left-hand circular polarization gain of the antenna proposed in the embodiment of the present invention varies with frequency.

[0023] Fig. 9 The return loss of the antenna proposed in the embodiment of the present invention |S 11 |Graph of the curve as a function of frequency.

[0024] Fig.10 The graph is a graph showing the variation of the left-hand circular polarization axial ratio of the antenna proposed in the embodiment of the present invention with frequency.

[0025] Fig.11 The radiation patterns of the antenna proposed in the embodiment of the present invention at 15 GHz, where (a) is the pattern in the plane of φ=0°, and (b) is the pattern in the plane of φ=90°.

[0026] Fig.12 The graph is a single-station radar cross section (RCS) of the antenna proposed in the embodiment of the present invention when the x-polarized wave is normally incident and compared with a metal plate of the same size.

[0027] Figure numerals: 1. Dual-frequency spiral geometric phase metasurface; 2. Radial line slot array antenna; 3. Double-headed arrow metal pattern; 4. Dielectric substrate of geometric phase metasurface; 5. Annular slot; 6. Coaxial feeding probe; 7. Herringbone slot pair array; 8. Dielectric substrate of radial line slot array antenna; 9. Arrow pattern; 10. Bent connecting line pattern; 11. Upper geometric phase unit; 12. Lower radial line slot array antenna unit. DETAILED DESCRIPTION

[0028] The following description clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention proposes a radial line slot array antenna that uses a dual-frequency spiral geometric phase metasurface to achieve dual-band RCS reduction, effectively protecting the excellent radiation performance of the RLSA. The spirally arranged geometric phase metasurface array forms a phase distribution similar to a vortex beam with a generated mode number of ±2. The scattered wave has a zero point in the side-ray direction and spreads in a cone shape to the surroundings, which can effectively reduce the RCS of a single station. The geometric phase unit is designed to work in dual frequencies, and is miniaturized and arranged in the same spiral as the RLSA, realizing the integration of the radiation scattering structure, ensuring the accuracy of the RLSA array design, and eliminating the interference of the metasurface on the radiation aperture field. Therefore, while achieving dual-frequency broadband RCS reduction at both ends of the radiation band, the radiation performance of the RLSA is well protected.

[0030] like Figure 1 As shown, a radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction includes an upper dual-frequency spiral geometric phase metasurface 1 and a lower radial line slot array antenna 2.

[0031] The spiral geometric phase metasurface 1 comprises: a spirally arranged double-headed arrow metal pattern 3 and a dielectric substrate 4; the double-headed arrow metal pattern comprises two right-angled arrow patterns 9 symmetrical about the origin and a centrally connected bent metal wire 10 bent at a right angle;

[0032] Furthermore, the resonant length of the arrow pattern mainly controls the high-frequency operating frequency band in the dual frequency band; the length of the bent metal wire mainly controls the low-frequency operating frequency band in the dual frequency band, and by adjusting the bending pattern, the unit period size can be controlled while keeping the resonant frequency band fixed; the width of the arrow and the bending line and the cavity height affect the intra-cavity phase superposition of the geometric phase unit 11, and therefore have an impact on its performance within the operating frequency band.

[0033] The radial line slot array antenna 2 comprises a short-circuit coaxial feeding probe 6 penetrating the waveguide, an annular slot 5 introduced at the center of the top of the waveguide, a herringbone slot pair array 7 loaded on the upper surface of the waveguide and arranged in a spiral manner, and a single-layer radial line waveguide 8 filled with a dielectric;

[0034] Furthermore, the herringbone slot pair includes two rectangular slots of the same size and perpendicular to each other, and the radial spacing in the radial transmission direction of the waveguide is one-quarter of the waveguide wavelength; the herringbone slot pair corresponds to the double-headed arrow pattern on the upper layer, and is arranged in a spiral with equal circumferential spacing to achieve left-handed circularly polarized radiation, and its radial spacing S ρ Set to one waveguide wavelength, circumferential spacing Set to half the waveguide wavelength; by adjusting the length of the "human" shaped gap pair, its normalized radiation power P is controlled rad , the length of the slots in the entire array increases gradually from the inside to the outside, so as to control the antenna aperture field to be evenly distributed; the slot pairs in the outermost circle all adopt the maximum length to reduce the power dissipation of the waveguide terminal and improve the antenna radiation efficiency;

[0035] Furthermore, the annular gap 5 takes the center point of the upper surface of the radial waveguide as the center, and the impedance matching of the antenna is achieved by adjusting the inner and outer diameters thereof.

[0036] There is an air gap between the upper dual-frequency spiral geometric phase metasurface and the lower radial line slot array antenna, and its height satisfies the phase superposition condition in the cavity formed by the metasurface and the ground.

[0037] The present invention is further described in detail below with reference to the embodiments.

[0038] Example

[0039] Reference Figures 1 to 5 The embodiment of the present invention discloses a radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction, which is as follows:

[0040] It includes an upper dual-frequency spiral geometric phase metasurface 1 and a lower radial line slot array antenna 2, forming an antenna with a diameter of 218 mm and a height of 12.3 mm.

[0041] The spiral geometric phase metasurface includes: a spirally arranged double-headed arrow metal pattern and a dielectric substrate; the double-headed arrow metal pattern includes arrow patterns with two ends symmetrical about the origin and a bent metal wire connected in the middle.

[0042] In order to realize the integrated design of the radiation scattering unit, the period size of the geometric phase unit is set to be the same as the radiation unit period of the radial line slot array, with a width of p1 = 6.9 mm and a length of p2 = 11.5 mm. In order to meet the resonance condition and working frequency band of the dual-frequency geometric phase unit, the upper medium is selected as F4BM450 (dielectric constant ε r =4.5, loss tangent tanδ = 0.002), cavity height h c=8.8mm; In order to realize the dual-band broadband working characteristics of the geometric phase unit, its parameter dimensions are set as arrow arm length a1=2.4mm, arrow arm width w1=0.3mm, metal bending line branch lengths a2=2.4mm, a3=1.6mm, a4=1.4mm, a5=1.2mm, and metal bending line width w2=0.2mm.

[0043] Figure 6 The co-polarization and cross-polarization reflection coefficient curves of the dual-frequency geometric phase unit under circularly polarized wave irradiation were simulated and calculated. It can be seen that the geometric phase unit has high-amplitude co-polarization reflection and cross-polarization reflection below -10dB in the low-frequency band of 4.6GHz to 10.4GHz and the high-frequency band of 18.8GHz to 23.6GHz, showing good dual-band geometric phase working characteristics. In these two high and low frequency bands, a conversion efficiency close to 1 can be obtained from the incident circularly polarized wave to the co-polarized reflected wave, and the co-polarization reflection phase introduced by the unit geometric rotation angle is twice the rotation angle. In the RLSA radiation band near 15GHz, the geometric phase unit is in a non-resonant state to reduce the impact on radiation.

[0044] The radial line slot array antenna comprises: a single-layer radial line waveguide filled with dielectric, a herringbone slot pair array loaded on the upper surface of the waveguide and arranged in a spiral manner, a short-circuit coaxial feeding probe penetrating the waveguide, and an annular slot introduced at the center of the top of the waveguide.

[0045] The dielectric-filled single-layer radial line waveguide adopts a dielectric substrate F4BM300 (ε r =3.0, tanδ=0.0015), waveguide wavelength λ g =11.5mm; the herringbone slit pair includes two rectangular slits of the same size and perpendicular to each other, with a center radial spacing of 1 / 4λ g ; The slit length l varies with the radial distance, and the slit width w is set to 0.9 mm; the "human" shaped slit pairs are arranged in a spiral with equal circumferential spacing, and their radial spacing S ρ Set to λ g , Circumferential spacing Set to 1 / 2λ g ; In order to achieve impedance matching of the radial line slot array antenna, the inner diameter R1 of the annular slot etched at the center of the top of the waveguide is 0.6 mm, and the outer diameter R2 is 1.1 mm; the diameter of the coaxial feed probe is φ p =0.6mm; the unit follows the clockwise spiral line from the minimum radial distance ρ min =17.3mm to the maximum radial distance ρ max =104mm are arranged in sequence to achieve left-hand circular polarization.

[0046] analyze Figure 5 The radiation characteristics of the radiation scattering integrated unit composed of the lower radial line slot array antenna unit 12 and the geometric phase unit 11 are shown. Figure 7 The axial ratio and normalized radiated power P are calculated by simulation. rad From the curve of the change with the gap length, it can be seen that the axial ratio of the integrated radiation scattering unit of the embodiment of the present invention is always lower than 2dB within the available gap length variation range, and the normalized radiation power gradually increases to about 0.9 with the increase of the gap length, and the circularly polarized radiation performance is good.

[0047] The radiation scattering integrated unit composed of the RLSA slot pair unit and the geometric phase unit in the embodiment of the present invention is arranged in a spiral manner according to the aperture field uniform distribution theory, and the simulation results of the antenna overall array are as follows:

[0048] Figure 8 This is a simulation calculation result of the gain versus frequency curve of the antenna proposed in the embodiment of the present invention. It can be seen that the antenna proposed in the embodiment of the present invention reaches a peak gain of 28.8dBic at 14.8GHz, the corresponding aperture efficiency is 66.8%, and its 3dB gain bandwidth is 14.5GHz to 15.6GHz.

[0049] Fig. 9 and Fig.10 are respectively the axial ratio and return loss of the antenna proposed in the embodiment of the present invention. 11 |From the simulation calculation results of the frequency variation curve, it can be seen that the axial ratio of the antenna proposed in the embodiment of the present invention is lower than 1.5dB within the observation frequency band. 11 |All below -10dB, good performance.

[0050] Fig.11 (a) and (b) are respectively the simulation calculation results of the radiation patterns of the antenna proposed in the embodiment of the present invention at φ=0° plane and φ=90° plane at 15GHz. It can be seen that the side lobe levels of the antenna proposed in the embodiment of the present invention at φ=0° plane and φ=90° plane are -11.5dB and -20.2dB respectively.

[0051] Fig.12 This is a graph of single-station RCS simulation calculation results of the antenna proposed in an embodiment of the present invention and a metal plate of the same size when the x-polarized wave is normally incident. It can be seen that compared with the metal plate of the same size, the antenna proposed in an embodiment of the present invention achieves a dual-band RCS reduction of more than 10 dB in the frequency band range of 4.5 GHz to 17.2 GHz in the low frequency band and 19.8 GHz to 23.7 GHz in the high frequency band.

[0052] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction, characterized in that: It comprises an upper dual-frequency spiral geometric phase metasurface (1) and a lower radial line slot array antenna (2); The upper spiral geometric phase metasurface (1) comprises a dielectric substrate (4) and a spirally arranged double-headed arrow metal pattern array etched thereon; the double-headed arrow metal pattern (3) comprises arrow patterns (9) symmetrical about the origin at both ends and a bent metal wire (10) connected in the middle; The lower radial line slot array antenna (2) comprises a dielectric-filled single-layer radial line waveguide (8), a herringbone slot pair array (7) loaded on the upper surface of the waveguide and arranged in a spiral manner, a short-circuit coaxial feeding probe (5) penetrating the waveguide, and an annular slot (6) introduced at the center of the top of the waveguide; An air gap exists between the upper dual-frequency spiral geometric phase metasurface (1) and the lower radial line slot array antenna (2).

2. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 1, characterized in that: The herringbone slot pair includes two rectangular slots of the same size and perpendicular to each other, and the radial spacing in the radial transmission direction of the waveguide is one quarter of the waveguide wavelength.

3. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 2, characterized in that: The "human" shaped slots are arranged in a spiral with equal circumferential spacing to achieve left-hand circularly polarized radiation. The radial spacing S ρ Set to one waveguide wavelength and circumferential spacing S φ Set to half the waveguide wavelength.

4. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 3, characterized in that: By adjusting the length of the "human" shaped gap pair, the normalized radiation power P can be controlled. rad The length of the slots in the entire array increases gradually from the inside to the outside, thereby controlling the antenna aperture field to be evenly distributed; the length of the outermost circle of slot pairs is set to achieve the maximum P in the design rad Length.

5. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 2, characterized in that: The pairs of "human" shaped gaps correspond one to one with the double-headed arrow patterns on the upper layer.

6. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 1, characterized in that: The arrow pattern (9) is a right-angle arrow pattern.

7. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 1, characterized in that: The annular gap (6) takes the central point of the upper surface of the radial line waveguide as the center of the circle, and the impedance matching of the antenna is achieved by adjusting the inner and outer diameters thereof.

8. The radial line slot array antenna with integrated radiation and scattering design to achieve dual-band RCS reduction according to claim 1, characterized in that: The bent metal wire (10) is a metal wire that is bent at a right angle and is centrally symmetrical.

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