A high-gain low-radar cross section integrated metasurface lens antenna design method and antenna

Abstract

The application provides a high-gain low-RCS integrated metasurface lens antenna design method and an antenna. The method selects a patch antenna as a feed source, forms a metasurface lens through a transmission phase correction unit, performs phase compensation on a wave front of the feed source, forms a plane wave front to realize beam focusing, and improves gain and bandwidth. The design sets a distance between the lens and the patch antenna as a half wavelength, expands a metal floor area to be consistent with the lens, and constructs an F-P resonant cavity. Electromagnetic waves are reflected and transmitted in the cavity multiple times to form in-phase superposition, further improve main lobe gain, and suppress a backward beam. Meanwhile, a gradient phase reflection surface is formed by gradually arranging units, the main lobe intensity of reflected waves is reduced based on a generalized reflection theorem, in-band RCS reduction is realized, and radar stealth performance is enhanced. The application utilizes a single-layer metasurface structure to cooperate with an F-P resonant cavity, overcomes defects of narrow bandwidth and low efficiency of a traditional antenna, and has the advantages of low cost, low profile and high integration.

Description

Technical Field

[0001] This invention belongs to the field of microwave and millimeter-wave band technology, specifically relating to a design method and antenna for a high-gain, low-RCS integrated metasurface lens antenna. Background Technology

[0002] Improving antenna gain has always been a key focus of antenna research. Fresnel zone plate (FZP) antennas and Fabry-Pérot (FP) resonant cavity antennas are both effective methods for increasing antenna gain. FZP antennas, based on the principle of transmission phase correction, possess wide bandwidth and high gain, but suffer from low radiation efficiency due to back-side energy loss. FP resonant cavity antennas utilize a half-wavelength reflector to form a resonant cavity, achieving multiple reflections and in-phase superposition of electromagnetic waves to improve gain. Their structure exhibits high gain and low profile characteristics, but typically has a narrow bandwidth. On the other hand, improving antenna gain often means increasing the antenna aperture, resulting in a larger radar cross section (RCS). Antennas without low RCS design, directly installed on stealth-capable equipment, often severely impact the overall stealth performance of the equipment. Summary of the Invention

[0003] Objective of the Invention: The technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a design method and antenna for a high-gain, low-RCS integrated metasurface lens antenna, which simultaneously possesses transmission phase correction, FP resonance, and reflection gradient phase performance, achieving broadband, high-gain, and low-RCS characteristics. This invention designs four types of integrated transmission / reflection phase correction units, which, in combination with an array arrangement, form an integrated structure of phase correction lens / FP resonant cavity / gradient phase reflecting surface.

[0004] The method includes the following steps: Step 1: Arrange the transmission phase correction units with different numbers in a concentric circle to obtain a 9×9 phase correction metasurface lens, so that the transmitted electromagnetic wave produces a relatively uniform phase distribution on the surface of the phase correction metasurface lens.

[0005] Step 2: The distance between the phase-corrected metasurface lens and the metal ground is controlled at half the wavelength, and the transmission phase correction unit with the largest reflection coefficient is arranged at the center of the phase-corrected metasurface lens to form an FP resonant cavity. Step 3: The transmission phase correction unit and the metal floor work together to form the reflection phase correction unit. The reflection phases of adjacent reflection phase correction units differ by 90°. The gradually changing arrangement forms a gradient phase reflection surface that scatters the reflected waves in all directions.

[0006] The present invention also provides an antenna implemented using the method described above, comprising a phase-corrected metasurface lens and a matching microstrip patch antenna; The matching microstrip patch antenna is positioned below the phase-corrected metasurface lens; The phase-correcting metasurface lens is obtained by arranging transmission phase correction units with different numbers; The transmission phase correction unit includes a metal patch and a dielectric substrate.

[0007] The metal patch is a Jerusalem cross structure with a square frame in the center.

[0008] There are four types of transmission phase correction units with different numbers: first transmission phase correction unit I, second transmission phase correction unit II, third transmission phase correction unit III, and fourth transmission phase correction unit IV. The transmission phase correction units with different numbers are arranged in concentric circles, from the inside out as I, II, III, IV, and I.

[0009] The four types of transmission phase correction units cover half a phase period for the phase correction of the transmitted wave, and the phase correction of adjacent numbered transmission phase correction units for the transmitted wave is... It shows a monotonically increasing trend. , i =1, 2, 3, 4, This represents the phase correction amount of the transmitted wave by the i-th transmission phase correction unit.

[0010] The transmission phase correction units on the phase correction metasurface lens are arranged according to the following pattern: When an electromagnetic wave with focal length F and wavelength λ arrives at a unit at a linear distance R from the center of the phase-correcting metasurface lens, generated by the matching microstrip patch antenna radiator and the phase-correcting metasurface lens, the phase delay will occur. for: , The phase delay at the center of the phase-corrected metasurface lens is selected as the reference phase. The first transmission phase correction unit I is arranged at the center of the phase correction metasurface lens, and the correction amount is... ;when The phase correction amount selected for the transmission phase correction unit at a straight-line distance R from the center of the phase correction metasurface lens is: i = 1, 2, 3, 4 (Note: If in the calculation formula...) If the subscript number is greater than 4, then the number is reduced by an integer multiple of 4 to make it fall within the range of 1 to 4.

[0011] The electromagnetic waves emitted by the matching microstrip patch antenna are formed into an approximately planar equiphase surface (i.e., wavefront) by a phase-corrected metasurface lens.

[0012] In one embodiment of the present invention, the matching microstrip patch antenna is a three-layer stacked structure, which, from top to bottom, consists of: a microstrip radiating patch disposed on the upper surface of a dielectric substrate, a dielectric substrate, and a metal ground plane disposed on the lower surface of the dielectric substrate.

[0013] The metal ground plane of the matching microstrip patch antenna also serves as the reflector ground plane of the FP resonant cavity. The metal ground plane has the same area as the phase-correcting metasurface lens. The metal ground plane is located below the phase-correcting metasurface lens and is half a wavelength away from the phase-correcting metasurface lens. Furthermore, the reflection coefficient of the first transmission phase correction unit I for the incident signal is greater than that of the second transmission phase correction unit II, the third transmission phase correction unit III, and the fourth transmission phase correction unit IV for the incident signal.

[0014] In one embodiment of the present invention, the radiator of the matching microstrip patch antenna is a square metal patch with a U-shaped slot. The matching microstrip patch antenna is back-fed, with a coaxial feed line passing through the dielectric substrate from the back of the metal ground plane. The inner conductor probe (a physical structure inherent in back-fed antenna) is connected upward to the microstrip radiating patch, and the outer conductor (a physical structure inherent in back-fed antenna) is shorted to the metal ground plane. The radio frequency signal is injected into the radiator from the rear of the antenna.

[0015] The electromagnetic waves emitted by the matching microstrip patch antenna are partially reflected by the phase-corrected metasurface lens and reflected more than twice in the FP cavity formed by the metal ground and the phase-corrected metasurface lens, and then radiated forward successively. The phase difference of one round trip is 2π, which satisfies the resonance condition of the FP resonant cavity. The electromagnetic waves radiated forward successively have the same phase, and the in-phase superposition signal enhances the forward beam.

[0016] The transmission phase correction unit and the metal floor directly below it constitute a reflection phase correction unit; the four transmission phase correction units correspond to the four reflection phase correction units; the reflection phase correction units perform total reflection of the electromagnetic waves incident in front; the reflection phase difference of each adjacent numbered reflection phase correction unit for the incident uniform plane wave increases by approximately 90°; the reflection phase difference of the four reflection phase correction units covers one phase period.

[0017] The transmission phase correction units are arranged in a concentric structure from the inside out. Each pair of adjacent concentric layers consists of transmission phase correction units with a 90° phase difference between reflections. When a plane wave is incident, it generates a reflected wave with a gradient phase on the surface of the phase correction metasurface lens, and thus the reflected wave is scattered in all directions.

[0018] When the incident beam irradiates on the phase-corrected metasurface lens with a unit period of P, the incident beam angle and the reflected beam angle are expressed by the generalized reflection law as: , where is the phase difference between each adjacent unit, with a value of about 90°. According to the analysis of the above formula, when the detection signal is incident vertically, the enhanced reflected beam presents a concave shape, and the main lobe radiation direction forms an angle of about 20° with the normal line.

[0019] The present invention has the following beneficial effects: 1. The present invention achieves the effect of broadband gain amplification.

[0020] 2. The present invention achieves the gain amplification effect through the synergistic action of the F-P resonant cavity and the phase-corrected metasurface lens, and overcomes the shortcomings of narrow bandwidth of the F-P antenna and low radiation efficiency of the metasurface lens.

[0021] 3. The present invention achieves the in-band RCS reduction effect, which is beneficial to radar stealth.

[0022] 4. The present invention can realize all the above effects only through a single-layer metasurface structure matched with a supporting microstrip patch antenna, which saves costs and reduces the profile of the antenna. Brief Description of the Drawings

[0023] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0024] Figure 2 is a schematic structural diagram of the transmission phase correction unit of the present invention.

[0025] Figure 3 is a schematic diagram of the reflection phase of the transmission phase correction unit of the present invention.

[0026] Figure 4 is a schematic diagram of the transmission phase of the transmission phase correction unit of the present invention.

[0027] Figure 5 is a schematic diagram of the transmission and reflection amplitudes of the transmission phase correction unit of the present invention.

[0028] Figure 6 is a schematic structural diagram of the supporting patch antenna of the present invention.

[0029] Figure 7 is a comparison diagram of the correction phase of the present invention.

[0030] Figure 8 is a diagram of the port reflection parameter of the present invention.

[0031] Figure 9 This is a diagram illustrating the single-station RCS reduction effect of the present invention.

[0032] Figure 10 This is a comparison chart of the gain amplification effect of the present invention at 14GHz.

[0033] Figure 11 This is a comparison chart of the gain curves of the present invention.

[0034] Explanation of reference numerals in the attached figures: 1, phase-corrected metasurface lens; 2, matching microstrip patch antenna. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0036] This invention provides a high-gain, low-RCS integrated metasurface lens antenna, such as... Figure 1 As shown, it includes a phase-corrected metasurface lens 1 and a matching microstrip patch antenna 2.

[0037] like Figure 1 As shown, the phase-corrected metasurface lens 1 is obtained by arranging transmission phase correction units. The transmission phase correction units with different numbers are arranged in concentric circles. According to... Figure 2 The numbering of each unit shown is as follows: the transmission phase correction units are numbered I, II, III, IV, and I from the inside out. The dielectric substrate of the phase correction metasurface lens is F4b with a dielectric constant of 2.2, a thickness of H1=1mm, and a width of W=72mm.

[0038] like Figure 1 As shown, a microstrip patch antenna 2 is positioned below the phase-corrected metasurface lens 1, with an air layer of height H2 = 12 mm between them. The dielectric substrate of the antenna has a thickness of H3 = 1 mm and a width of W = 72 mm. The metal patch, serving as the radiator, is located at the center of the dielectric substrate and is back-fed.

[0039] like Figure 2 As shown, the transmission phase correction unit consists of a metal patch unit and a dielectric substrate. The unit period of a single transmission phase correction unit is p = 8 mm. The metal patch unit is shaped like a Jerusalem cross with a square frame in the center. The width of the metal strips constituting the patch unit is W0 = 0.2 mm, and the length of each metal strip is... The relationship (where n represents the unit number) is as follows: Figure 2 As shown, where , , , .

[0040] like Figure 3 As shown, when the simulation sets the unit boundary conditions to a periodic structure and the electromagnetic wave is incident perpendicularly along the normal, the reflected wave phases of the four reflection phase correction units differ by approximately 90° in the frequency band from 13.7 GHz to 16.3 GHz.

[0041] like Figure 4 As shown, the phase values ​​of the four transmission phase correction units are shifted forward sequentially in the order of Unit I - Unit II - Unit III - Unit IV.

[0042] like Figure 5 As shown, among the four types of transmission phase correction units, unit I has the strongest reflection, so arranging unit I at the center of the metasurface lens can achieve the most ideal resonance effect.

[0043] like Figure 6 As shown, the radiator antenna in the matching microstrip patch antenna is a square metal patch with a U-shaped slot, and the feed point is located at the center of the radiator. The patch side length is a = 7 mm; the vertical slot length is b = 3.6 mm; the horizontal slot length is c = 3.6 mm; and the slot width is d = 0.2 mm.

[0044] like Figure 7 As shown, the phase of electromagnetic waves is significantly corrected after passing through the metasurface lens, with the variation range limited to within 0°~90°, and the overall phase distribution is smoother.

[0045] like Figure 8 As shown, the port reflection coefficient of the matching microstrip patch antenna is less than 10dB in the 13.8GHz~14.5GHz range. This frequency band is within the frequency band where the RCS reduction-gain amplification integrated metasurface lens realizes the pattern focusing function.

[0046] like Figure 9 As shown, directly adding an FP resonator to a lens antenna system without RCS reduction design will significantly increase the RCS. However, after RCS reduction design, compared to the antenna without RCS reduction design, a 6dB RCS reduction can be achieved in the 13.6GHz~18GHz range, and the antenna operating frequency is within the RCS reduction band. Even compared to a lens antenna system without an FP resonator, an average RCS reduction of more than 3dB can be achieved in the 13.8GHz~17.7GHz range.

[0047] like Figure 10 As shown, the radiation gain of the microstrip patch antenna without a metasurface lens at 14 GHz is 7.9 dBi. After adding a metasurface lens, the gain increases to 11.85 dBi. After introducing a resonant cavity, the gain is 15.32 dBi, resulting in a total gain increase of 7.42 dB.

[0048] like Figure 11 As shown, the gain of the single antenna is significantly improved after introducing a metasurface lens. Compared with the scheme without a resonant cavity, the gain is further improved after introducing the resonant cavity. As the frequency increases, the reflection of electromagnetic waves by the lens increases, resulting in increased back radiation and deteriorated radiation efficiency in the case of a single lens. Introducing a resonant cavity reduces back radiation, thereby further improving the gain. Overall, the present invention achieves a gain improvement of more than 6dB compared to a single antenna in the 12.7GHz~14.8GHz range.

[0049] This invention provides a design method and antenna for a high-gain, low-RCS integrated metasurface lens antenna. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A design method for a high-gain, low-RCS integrated metasurface lens antenna, characterized in that, include: Step 1: Arrange the transmission phase correction units with different numbers in a concentric circle to obtain a 9×9 phase correction metasurface lens, so that the transmitted electromagnetic wave produces a relatively uniform phase distribution on the surface of the phase correction metasurface lens. Step 2: The distance between the phase-corrected metasurface lens and the metal ground is controlled at half the wavelength, and the transmission phase correction unit with the largest reflection coefficient is arranged at the center of the phase-corrected metasurface lens to form an FP resonant cavity. Step 3: The transmission phase correction unit and the metal floor work together to form the reflection phase correction unit. The reflection phases of adjacent reflection phase correction units differ by 90°. The gradually changing arrangement forms a gradient phase reflection surface that scatters the reflected waves in all directions.

2. An antenna implemented using the method described in claim 1, characterized in that, This includes a phase-corrected metasurface lens and a matching microstrip patch antenna; The matching microstrip patch antenna is positioned below the phase-corrected metasurface lens; The phase-correcting metasurface lens is obtained by arranging transmission phase correction units with different numbers; The transmission phase correction unit includes a metal patch and a dielectric substrate.

3. The antenna according to claim 2, characterized in that, The metal patch is a Jerusalem cross structure with a square frame in the center.

4. The antenna according to claim 3, characterized in that, There are four types of transmission phase correction units with different numbers: first transmission phase correction unit I, second transmission phase correction unit II, third transmission phase correction unit III, and fourth transmission phase correction unit IV. The transmission phase correction units with different numbers are arranged in concentric circles, from the inside out as I, II, III, IV, and I.

5. The antenna according to claim 4, characterized in that, The four types of transmission phase correction units cover half a phase period for the phase correction of the transmitted wave, and the phase correction of adjacent numbered transmission phase correction units for the transmitted wave is... It shows a monotonically increasing trend. , i =1, 2, 3, 4, This represents the phase correction amount of the transmitted wave by the i-th transmission phase correction unit.

6. The antenna according to claim 5, characterized in that, When an electromagnetic wave with focal length F and wavelength λ arrives at a unit at a linear distance R from the center of the phase-correcting metasurface lens, generated by the matching microstrip patch antenna radiator and the phase-correcting metasurface lens, the phase delay will occur. for: ， The phase delay at the center of the phase-corrected metasurface lens is selected as the reference phase. The first transmission phase correction unit I is arranged at the center of the phase correction metasurface lens, and the correction amount is... ;when The phase correction amount selected for the transmission phase correction unit at a straight-line distance R from the center of the phase correction metasurface lens is: i = 1, 2, 3, 4.

7. The antenna according to claim 6, characterized in that, The metal ground plane of the matching microstrip patch antenna also serves as the reflective ground plane of the FP resonant cavity. The metal ground plane has the same area as the phase-correcting metasurface lens. The metal ground plane is located below the phase-correcting metasurface lens and is half a wavelength away from the phase-correcting metasurface lens. Furthermore, the reflection coefficient of the incident signal by the first transmission phase correction unit I is greater than that of the second transmission phase correction unit II, the third transmission phase correction unit III, and the fourth transmission phase correction unit IV.

8. The antenna according to claim 7, characterized in that, The electromagnetic waves emitted by the matching microstrip patch antenna are reflected by the phase-corrected metasurface lens, and are reflected more than twice in the FP cavity formed by the metal ground and the phase-corrected metasurface lens, and then radiated forward successively; the phase difference of one round trip is 2π, which satisfies the resonance condition of the FP resonant cavity. Electromagnetic waves radiated forward in successive waves have the same phase, and the in-phase superposition of signals enhances the forward beam.

9. The antenna according to claim 8, characterized in that, The transmission phase correction unit and the metal floor directly below it constitute a reflection phase correction unit; the four types of transmission phase correction units correspond to the four types of reflection phase correction units; the reflection phase correction units perform total internal reflection of the incident electromagnetic wave; the reflection phase difference of each adjacent numbered reflection phase correction unit for the incident uniform plane wave is approximately equal to... Incremental; the reflection phase difference of the four reflection phase correction units covers one phase period.

10. The antenna according to claim 9, characterized in that, The transmission phase correction units are arranged in a concentric structure from the inside out. Each pair of adjacent concentric layers consists of transmission phase correction units with a 90° phase difference between reflections. When a plane wave is incident, it generates a reflected wave with a gradient phase on the surface of the phase correction metasurface lens, and thus the reflected wave is scattered in all directions.

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