A high-gain co-boresight beam scanning antenna with large frequency ratio

Abstract

The application is a high-gain common-aperture beam scanning antenna with a large frequency ratio, the uppermost two dielectric plates are printed with a metasurface unit structure, and have a phase gradient change along a certain direction in a two-dimensional plane, the two dielectric plates are separated by a certain distance and can rotate around a normal axis. The lower two dielectric plates are fixed, a periodic structure is printed on the upper dielectric plate; a microstrip patch antenna for feeding a low-frequency high-gain resonant cavity antenna is printed in the center of the upper surface of the lower dielectric plate, and polarization conversion reflection units for a high-frequency band are printed around the microstrip patch antenna; the lower surface of the lower dielectric plate serves as a ground plate. A rectangular notch is respectively left in the center of the microstrip patch antenna and the ground plate, the lower side of the dielectric plate is connected with a standard WR34 waveguide, and the waveguide feeds the folded reflection array antenna for a high-frequency band. Electromagnetic waves can be transmitted and received in the Sub-6GHz frequency band and the millimeter wave frequency band in the field of 5G communication, and the high-frequency band can realize beam scanning.

Description

TECHNICAL FIELD

[0001] The present application relates to a co-boresight antenna, in particular to a high-gain co-boresight beam scanning antenna with a large frequency ratio, and belongs to the technical field of co-boresight beam scanning antenna manufacturing in the Sub-6GHz frequency band and the millimeter wave frequency band in 5G communication. BACKGROUND

[0002] With the advent of the 5G communication era, the spectrum resource is constantly expanding to a higher frequency band. The existing 5G communication system involves two frequency bands: the Sub-6GHz frequency band and the millimeter wave frequency band. Because the two frequency bands are far apart, it is usually difficult to use an antenna to work in both frequency bands. Therefore, the research on multi-frequency antennas (especially for frequency bands far apart) has attracted widespread attention. On the other hand, the millimeter wave band requires a high-gain narrow-beam fast scanning function due to its high path loss. With the development of antenna technology, some new types of metamaterial structures have emerged. These metamaterials often exhibit different properties at different frequencies, which makes it possible for an antenna to achieve different functions in the same aperture plane. Co-boresight antenna is a type of antenna that can meet the simultaneous work of multiple antennas in multiple frequency bands in the same aperture plane, which can greatly reduce the size of the antenna aperture plane and thus reduce the processing cost of the antenna. SUMMARY

[0003] Technical problem: In order to overcome the deficiencies in the prior art, the present application provides a high-gain co-boresight beam scanning antenna with a large frequency ratio, which solves the problem of realizing antenna co-boresight in the Sub-6GHz frequency band and the millimeter wave frequency band (two frequency bands far apart) in 5G communication, high gain in dual-band and beam scanning function in high frequency band. That is, the same aperture does not require a unit group array to simultaneously realize high-gain radiation of the antenna in dual-band and beam scanning in high frequency band.

[0004] Technical solution: To solve the above technical problems, the application adopts a high-gain common-aperture beam scanning antenna with a large frequency ratio, which is composed of four layers of dielectric plates and a feeding structure. The upper surfaces of the upper two layers of dielectric plates, i.e. the first layer of dielectric plate and the second layer of dielectric plate, are respectively printed with phase gradient metasurface structures to form periodic metasurfaces, and the phase gradient changes along a certain direction in the two-dimensional plane. The two layers of dielectric plates are separated by a certain distance, and the upper two layers of dielectric plates can rotate around the normal axis. The lower two layers of dielectric plates, i.e. the third layer of dielectric plate and the fourth layer of dielectric plate, are fixed and immovable. The third layer of dielectric plate is printed with a metasurface periodic structure, and a microstrip patch antenna for feeding a low-frequency high-gain resonant cavity antenna is printed on the center of the upper surface of the fourth layer of dielectric plate. A polarization conversion reflection structure for high-frequency is printed around the microstrip patch antenna. The lower surface of the fourth layer of dielectric plate serves as a ground plate. The fourth layer of dielectric plate has a rectangular notch in the center of the microstrip patch antenna and the ground plate. The lower side of the fourth layer of dielectric plate is connected to a standard WR34 waveguide horn, which feeds the high-frequency folded reflectarray antenna through the waveguide horn.

[0005] The metasurface periodic structure is a partially reflective surface for the low-frequency high-gain resonant cavity antenna and a polarization grid for the high-frequency folded reflectarray antenna.

[0006] The low-frequency high-gain resonant cavity antenna has a partially reflective surface on the surface of the third layer of dielectric plate, which together with the fourth layer of dielectric plate and the ground plate forms a high-gain resonant cavity. The microstrip patch antenna on the fourth layer of dielectric plate feeds the low-frequency high-gain resonant cavity antenna.

[0007] The high-frequency folded reflectarray antenna has a polarization grid on the surface of the third layer of dielectric plate, which can transmit electromagnetic waves of one polarization and reflect electromagnetic waves of the orthogonal polarization. The polarization conversion reflection structure on the fourth layer of dielectric plate can reflect high-frequency electromagnetic waves while performing polarization conversion and phase compensation. The standard WR34 waveguide horn in the fourth layer of dielectric plate feeds the high-frequency folded reflectarray antenna.

[0008] The low-frequency high-gain resonant cavity antenna and the high-frequency folded reflectarray antenna share the third layer of dielectric plate printed with metasurface periodic structures as the aperture for antenna radiation.

[0009] The metasurface periodic structure printed on the third layer of dielectric plate is composed of multiple metasurface units, which are arranged in a square.

[0010] The phase gradient metasurface structure on the upper two layers of dielectric plates is arranged in multiple groups, each group has multiple columns, and the metasurface units from the first column to the last column are arranged from small to large.

[0011] The phase gradient metasurface structure on the upper two dielectric plates has a phase gradient in the high frequency band and is transparent to the low frequency band, that is, the low frequency band electromagnetic waves radiated from the third dielectric plate aperture pass without reflection.

[0012] The height of the low frequency band high gain resonant cavity satisfies the condition of H=(1 / 2+n / 2)λ1, wherein λ1 is the free space wavelength of the low frequency center frequency electromagnetic wave, and n=0, 1, 2, …; and the focal diameter ratio of the high frequency band folded reflectarray antenna satisfies 2H / D=1 / 2, wherein D is the diameter length of the antenna aperture surface.

[0013] The polarization conversion reflection structure is composed of a plurality of rows of polarization conversion reflection units arranged in sequence, the reflection unit is composed of a rectangular patch, and the length and width of the rectangular patch determine the reflection phase required by polarization conversion.

[0014] Advantages: compared with the existing multi-band common aperture antenna, the present application eliminates the complex feed network of the traditional common aperture antenna, has a smaller profile height, and has a simpler structure; the present application forms two types of high gain antennas through the lower two dielectric plates, and the high gain resonant cavity antenna and the folded reflectarray antenna can be studied separately, so that the dual-band common aperture antenna has high independence and flexibility when designed, and theoretically, a common aperture antenna with any frequency ratio can be designed. The upper two dielectric plates form a high frequency band beam scanning function, and at the same time, the high gain beam of the low frequency band is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present application.

[0016] Figure 2 It is a side view of the overall structure of the present application.

[0017] Figure 3 It is a schematic diagram of the phase gradient metasurface structure of the present application.

[0018] Figure 4 It is a schematic diagram of the periodic structure of the metasurface of the present application which simultaneously has a polarization grid and a partial reflection function.

[0019] Figure 5 It is a schematic diagram of the polarization conversion reflection surface structure of the present application.

[0020] Figure 6 It is a schematic diagram of the periodic unit structure of the metasurface of the present application.

[0021] Figure 7 It is a reflection coefficient and port isolation curve diagram of the low frequency band of the present application.

[0022] Figure 8 This is the E-plane gain pattern for the low-frequency band of this invention.

[0023] Figure 9 This is the H-plane gain pattern for the low-frequency band of the present invention.

[0024] Figure 10 This is a graph showing the reflection coefficient and port isolation of the high-frequency band of this invention.

[0025] Figure 11 This is the E-plane gain pattern when the high-frequency band is not scanned according to the present invention.

[0026] Figure 12 This is the H-plane gain pattern when the high-frequency band is not scanned according to the present invention.

[0027] The diagram includes: first dielectric substrate 1, second dielectric substrate 2, third dielectric substrate 3, fourth dielectric substrate 4, phase gradient metasurface structure 5, metasurface periodic structure 6, microstrip patch antenna 7, polarization conversion reflection structure 8, standard WR34 waveguide horn 9, and ground plane 10. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] like Figures 1-6 As shown, the present invention discloses a high-gain common-aperture beam scanning antenna with a high frequency ratio, comprising four layers of dielectric substrates and a feeding structure. The upper surfaces of the top two dielectric substrates, namely the first dielectric substrate 1 and the second dielectric substrate 2, are respectively printed with phase gradient metasurface structures 5 to form periodic metasurfaces, and have phase gradient changes along a certain direction in a two-dimensional plane. The two dielectric substrates are separated by a certain distance, and the top two dielectric substrates can rotate around the normal axis. The bottom two dielectric substrates, namely the third dielectric substrate 3 and the fourth dielectric substrate 4, are fixed. The third dielectric substrate is located in the middle of the middle dielectric substrate. The plate 3 has a metasurface periodic structure 6 printed on it. At the center of the upper surface of the fourth dielectric plate 4, a microstrip patch antenna 7 is printed to feed a low-frequency high-gain resonant cavity antenna. The microstrip patch antenna 7 is surrounded by a high-frequency polarization conversion reflection structure 8. The lower surface of the fourth dielectric plate 4 serves as a ground plane 10. The fourth dielectric plate 4 has a rectangular notch in the center of the microstrip patch antenna 7 and the ground plane 10. The lower side of the fourth dielectric plate 4 is connected to a standard WR34 waveguide horn 9, which feeds the high-frequency folded reflective array antenna.

[0030] The two layers of medium substrates and the phase gradient metasurface printed thereon constitute a device with high frequency band beam scanning function. The metasurface periodic structure printed on the penultimate layer of medium substrate is a square ring with a grid structure in the middle. It has the characteristics of a partially reflective surface at low frequency band, can transmit a small part of electromagnetic waves and reflect most of the electromagnetic waves, and can form a high gain resonant cavity antenna together with the ground plane of the bottom layer of medium plate. The microstrip patch antenna printed on the bottom layer of medium plate feeds the resonant cavity antenna. Low frequency electromagnetic waves are reflected back and forth in the high gain resonant cavity multiple times, and finally form a beam with the same phase at the aperture plane, greatly improving the gain of the antenna. The beam encounters the two layers of phase gradient surfaces above it. Since the phase gradient surface is transparent to low frequency band, the beam will not be affected and will pass through without reflection. The metasurface periodic structure on the penultimate layer of medium substrate has the characteristics of a polarization grid at high frequency band, and can fully transmit electromagnetic waves of one polarization and fully reflect electromagnetic waves of orthogonal polarization. The polarization conversion and reflection unit printed on the bottom layer of medium plate can realize polarization conversion and phase compensation while fully reflecting high frequency electromagnetic waves, and can form a folded reflectarray antenna together with the polarization grid on the upper layer of medium plate. The standard WR34 waveguide horn connected to the bottom layer of medium plate feeds the high frequency band folded reflectarray antenna. The electromagnetic waves emitted from the waveguide are fully reflected back when reaching the polarization grid for the first time, and form a plane wave with the same phase at the aperture plane after polarization conversion and phase compensation by the reflection unit. The plane wave is radiated out when reaching the polarization grid for the second time, greatly improving the gain of the antenna. The two layers of phase gradient metasurfaces can change the beam direction by rotating around their respective normal central axes (z axes), thereby realizing high frequency band beam scanning function.

[0031] The super surface periodic structure 6 is a partially reflective surface for the low frequency high gain resonant cavity antenna, and is a polarization grid for the high frequency folded reflectarray antenna. The low frequency high gain resonant cavity antenna, the super surface periodic structure 6 on the surface of the third layer dielectric plate 3 has the performance of a partially reflective surface, and together with the fourth layer dielectric plate 4 and the ground plate 10 forms a high gain resonant cavity, the microstrip patch antenna 7 on the fourth layer dielectric plate 4 feeds the low frequency high gain resonant cavity antenna, the super surface periodic structure 6 on the surface of the third layer dielectric plate 3 of the high frequency folded reflectarray antenna has the performance of a polarization grid, and can make electromagnetic waves of one polarization mode pass through and reflect electromagnetic waves of a polarization mode orthogonal thereto, the polarization conversion reflection structure 8 on the fourth layer dielectric plate 4 can reflect high frequency electromagnetic waves while also performing polarization conversion and phase compensation, and the standard WR34 waveguide horn 9 in the middle of the fourth layer dielectric plate 4 feeds the high frequency folded reflectarray antenna. The low frequency high gain resonant cavity antenna and the high frequency folded reflectarray antenna share the third layer dielectric plate 3 printed with the super surface periodic structure 6 as the aperture for antenna radiation. The super surface periodic structure 6 printed on the upper layer dielectric plate is composed of a plurality of super surface units, and the plurality of super surface units are arranged in a square. The phase gradient super surface structure on the upper two layer dielectric plates is composed of a plurality of super surface structure units arranged in groups, each group has a plurality of columns, and the super surface units from the first column to the last column are arranged from small to large.

[0032] The phase gradient super surface structure 5 on the upper two layer dielectric plates has a phase gradient at the high frequency band, and is transparent to the low frequency band, i.e. the low frequency electromagnetic waves radiated by the aperture of the third layer dielectric plate 3 pass through without reflection; by rotating the upper two layer dielectric plates, the scanning of the high frequency electromagnetic wave beam can be realized. The polarization conversion reflection structure 8 is composed of a plurality of rows of polarization conversion reflection units arranged in sequence, the reflection unit is composed of a rectangular patch, and the length and width of the rectangular patch determine the reflection phase required for polarization conversion.

[0033] The height of the low frequency resonant cavity satisfies the condition H = (1 / 2 + n / 2)λ1, where λ1 is the free space wavelength of the low frequency center frequency electromagnetic wave, and n = 0, 1, 2…; the focal diameter ratio of the high frequency folded reflectarray antenna satisfies 2H / D = 1 / 2, where D is the diameter length of the antenna aperture surface.

[0034] As shown in Figure 6 The super surface periodic structure printed on the penultimate layer dielectric plate is composed of periodic unit structures, and the period is P. The unit structure is a square ring with a grid-shaped strip, the side length of the square ring is L, and the width is s. There are 8 grid-shaped strips in each square ring, and the width of each grid-shaped strip is s, and the distance between adjacent two grid-shaped strips is g. This structure has the characteristics of a partially reflective surface for low frequency signals and a polarization grid for high frequency signals.

[0035] To facilitate the explanation of the design process for each structural parameter, the following structural parameters are given: the square ring of the periodic metasurface unit structure has a side length of L = 7.4 mm, a width of s = 0.2 mm, and a period of P = 7.6 mm. The width of each grating bar is s = 0.2 mm, and the spacing between two adjacent grating bars is g = 0.6 mm. The center frequency f of the low-frequency unit is... L =5.4GHz, the distance between the bottom two dielectric substrates is approximately H=30mm; the center frequency of the high frequency is f H =25GHz, the diameter of both dielectric substrates is D=120mm. The height of the low-frequency high-gain resonant cavity satisfies the condition H≈1 / 2λ1, where λ1 is the free-space wavelength of the low-frequency center frequency electromagnetic wave; the focal diameter ratio of the high-frequency folded reflector antenna satisfies 2H / D=1 / 2, where D is the diameter of the antenna aperture. Using simulation software such as Ansoft's HFSS and CST's Microwave Studio CST, high-frequency simulations were performed on a computer to obtain the following results: Figure 7 , 10 The reflection coefficients S of the two frequency bands shown 11 Curve graph and port isolation S 21 Line graph; Figure 8 , Figure 9 The E-plane and H-plane gain patterns in the low-frequency band are shown. Figure 11 , Figure 12 The image shows the E-plane and H-plane gain patterns when the high-frequency band is not scanned. The curves obtained above were obtained under given conditions; similar curves can be obtained by changing the structural parameters. Further changes to the height of the resonant cavity or the diameter of the aperture surface can yield different operating frequency bands and corresponding antenna gains.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-gain co-boresight beam scanning antenna with large frequency ratio, characterized in that: The antenna is composed of four layers of dielectric plates and a feeding structure, the upper two layers of dielectric plates, i.e. the first layer of dielectric plate (1) and the second layer of dielectric plate (2), have phase gradient metasurface structures (5) printed on their upper surfaces to form periodic metasurfaces, and have phase gradient changes along a certain direction in a two-dimensional plane, the two layers of dielectric plates are separated by a certain distance, and the upper two layers of dielectric plates can be rotated around a normal axis; the lower two layers of dielectric plates, i.e. the third layer of dielectric plate (3) and the fourth layer of dielectric plate (4), are fixed, the third layer of dielectric plate (3) has a metasurface periodic structure (6) printed thereon, and the fourth layer of dielectric plate (4) has a microstrip patch antenna (7) for feeding a low-frequency high-gain resonant cavity antenna printed on the center of its upper surface, and the microstrip patch antenna (7) has a high-frequency polarization conversion reflection structure (8) printed around it; the lower surface of the fourth layer of dielectric plate (4) serves as a ground plate (10); the fourth layer of dielectric plate (4) has a rectangular gap in the center of the microstrip patch antenna (7) and the ground plate (10), respectively, and the lower side of the fourth layer of dielectric plate (4) is connected with a standard WR34 waveguide horn (9) to feed the high-frequency folded reflectarray antenna through the waveguide horn; The phase gradient metasurface structures (5) on the upper two layers of dielectric plates are arranged in multiple groups, each group has multiple columns, and the metasurface units from the first column to the last column are arranged from small to large; The phase gradient metasurface structures (5) on the upper two layers of dielectric plates have phase gradient at high frequency and are transparent to low frequency, i.e. the low-frequency electromagnetic waves radiated from the aperture of the third layer of dielectric plate (3) pass through without reflection; by rotating the upper two layers of dielectric plates, the scanning of high-frequency electromagnetic beams can be realized; The metasurface periodic structure (6) is a partially reflective surface for the low-frequency high-gain resonant cavity antenna and a polarization grid for the high-frequency folded reflectarray antenna; The metasurface periodic structure (6) printed on the third layer of dielectric plate is composed of multiple metasurface units arranged in a square.

2. The high-gain co-boresight beam scanning antenna with large frequency ratio according to claim 1, characterized in that: The low-frequency high-gain resonant cavity antenna, the metasurface periodic structure (6) on the surface of the third layer of dielectric plate (3) has the performance of a partially reflective surface, and together with the fourth layer of dielectric plate (4) and the ground plate (10) forms a high-gain resonant cavity, and the microstrip patch antenna (7) on the fourth layer of dielectric plate (4) feeds the low-frequency high-gain resonant cavity antenna.

3. The high-gain co-prime beam scanning antenna with large frequency ratio according to claim 2, characterized in that: The high-frequency folded reflectarray antenna, the metasurface periodic structure (6) on the surface of the third layer of dielectric plate (3) has the performance of a polarization grid, which can transmit electromagnetic waves of one polarization and reflect electromagnetic waves of the orthogonal polarization, and the polarization conversion reflection structure (8) on the fourth layer of dielectric plate (4) can reflect high-frequency electromagnetic waves while performing polarization conversion and phase compensation, and the standard WR34 waveguide horn (9) in the middle of the fourth layer of dielectric plate (4) feeds the high-frequency folded reflectarray antenna.

4. The high-gain co-prime beam scanning antenna with large frequency ratio according to claim 2 or 3, characterized in that: The low-frequency high-gain resonant cavity antenna and the high-frequency folded reflectarray antenna share the third layer of dielectric plate (3) printed with metasurface periodic structure (6) as the aperture for antenna radiation.

5. The high-gain co-prime beam scanning antenna with large frequency ratio according to claim 2, characterized in that: The height of the low-frequency high-gain resonant cavity satisfies the condition of H=(1 / 2+n / 2)λ1, wherein λ1 is the free space wavelength of the low-frequency center frequency electromagnetic wave, and n=0, 1, 2…; and the focal-diameter ratio of the high-frequency folded reflective array antenna satisfies 2H / D=1 / 2, wherein D is the diameter length of the antenna aperture surface.

6. The high-gain co-prime beam scanning antenna with large frequency ratio according to claim 3, characterized in that: The polarization conversion reflection structure (8) is composed of multiple rows of polarization conversion reflection units arranged in sequence, and the reflection units are composed of rectangular patches, and the length-width of the rectangular patches determines the reflection phase required by polarization conversion.

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