Multi-frequency multi-polarized wide-beam scanning base station system, and optimization design method

Abstract

The present invention relates to the field of high-rate mobile wireless communications. Disclosed are a multi-frequency multi-polarized wide-beam scanning base station system, and an optimization design method. The method comprises: on the basis of an aperture field expansion theory and a mode coupling theory, designing a conical horn feed source antenna capable of radiating a Gaussian fundamental mode beam, and providing a stable beam width and a stable phase center; designing a beam separation device based on a periodic structure, wherein the beam separation device includes band-pass frequency selective surfaces and a linear polarization grid; and combining front-end quasi-optical links of multiple frequency channels and multiple polarized channels, so as to increase the bandwidth and communication rate of a base station antenna. In the present invention, a genetic optimization algorithm is combined with reflector shaping, thereby effectively reducing the conflict between a shielding effect of a dual-reflector antenna and a scanning angle, and realizing the multiplication of a beam scanning angle.

Description

A multi-frequency multi-polarization wide-beam scanning base station system and optimization design method Technical Field

[0001] The present invention relates to the field of mobile high-speed wireless communications, and in particular to a multi-frequency multi-polarization wide-beam scanning base station system and an optimization design method. Background Art

[0002] With the development of digital communications in the late 1980s, mobile communications gradually became popular. Currently, the fifth-generation mobile communications system (5G) has entered commercial use. The advantages of 5G technology include higher speeds, lower latency, greater bandwidth, improved network reliability and security, and greater energy efficiency. High-speed mobile communication base station antenna technology will play a crucial role in the promotion of 5G and even 6G. Quasi-optical technology utilizes millimeter-wave wireless communications. It combines the characteristics of optical and microwave communications and is used in engineering for beamforming, beamforming, and spatial filtering. Based on optical principles, quasi-optical technology uses electromagnetic waves in the microwave and millimeter-wave frequency ranges to form beams and form beam-steering systems. Quasi-optical systems are currently being used in radar systems, satellite communications, and wireless communication networks.

[0003] Current mobile communication base station antenna technology has the following difficulties: low transmission rate, failure to achieve large bandwidth in the millimeter wave band; large loss in the millimeter wave band; small beam scanning limit angle, and poor ability to track moving targets.

[0004] In view of this, it is necessary to propose a multi-frequency, multi-polarization, wide-beam scanning base station system and an optimization design method. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a multi-frequency, multi-polarization, wide-beam scanning base station system and optimization design method to expand existing base station bandwidth while reducing transmission loss and enhancing beam scanning capabilities. The present invention utilizes 45GHz, 100GHz, and 220GHz conical corrugated horns as beam-generating devices, radiating a fundamental-mode Gaussian beam as the feed source for the initial signal. As an improvement over smooth-walled conical horns, the conical corrugated horn significantly reduces diffraction effects from the horn's metal edges, optimizes the axial symmetry of the radiation pattern, and reduces cross-polarization within the horn.

[0006] In general, the electromagnetic wave fed by a circular waveguide is The main mode is converted into Mode, which is an electromagnetic balance mode, and the good radiation performance of the conical corrugated speaker comes from this.

[0007] A linear polarization grating and 45 GHz and 220 GHz bandpass frequency selective surfaces serve as beam splitting devices, providing multi-channel beam separation and synthesis. The linear polarization grating can separate or synthesize vertically polarized beams and horizontally polarized beams, thereby meeting multi-polarization design requirements. The linear polarization grating has a relatively simple structure, consisting of metal wires tightly arranged on a vertical plane. A frequency selective surface is a surface structure that exerts a control effect on electromagnetic waves. It typically has a two-dimensional periodic structure and is composed of multiple periodic arrays of metal conductors or dielectrics. Using Floquet's periodic boundary theory, the frequency response characteristics of the frequency selective surface can be quickly and accurately calculated using the finite time-domain difference method (FDTD).

[0008] Ellipsoid mirrors with varying major and minor axes serve as beam focusing devices, leveraging the ellipsoid's beam focusing capabilities to fold and converge individual beam channels, thereby controlling the overall link volume. Based on the input beam parameters and the ellipsoid's ABCD beam transfer matrix, various outgoing beam parameters can be rapidly calculated. Furthermore, the ellipsoid's inherent metallic surface supports the system's wide bandwidth characteristics. Physical optics (PO) algorithms enable rapid simulation of the radiation field before and after beam transformation.

[0009] A large-aperture reflector antenna serves as the beam scanning device, providing high gain. The reflector antenna is the final quasi-optical component in the entire link, converging all beam channels and providing highly directional radiation into free space. By optimizing the reflector's shaping and slightly shifting the equivalent feed, wide-angle beam scanning is achieved, mitigating the conflict between the sub-reflector's obstruction effect and the beam scanning angle.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A multi-frequency, multi-polarization, wide-beam scanning base station system, comprising a beam generating device, a beam converging device, a beam separating device, and a beam scanning device;

[0012] The beam generating device is used to radiate an approximate Gaussian beam using a broadband conical horn feed source;

[0013] The beam focusing device utilizes the beam focusing characteristics of the ellipsoidal mirror to fold and converge the multi-beam channels;

[0014] The beam splitting device separates the multi-channel beams by using the beam splitting characteristics of the frequency selective surface and the linear polarization grid;

[0015] The beam scanning device realizes wide-angle beam scanning through a large-aperture reflector antenna after shape optimization.

[0016] Furthermore, the beam generating device includes: 45GHz, 100GHz and 220GHz conical corrugated horns, the depth of the mode conversion section groove is Gradually change to ,in is the center wavelength of the feed source; and the waist of the radiated Gaussian beam is The radius of the bell mouth is , The near-field energy distribution and the Gaussian base mode coupling degree reaches 98%, which can provide a stable phase center and beam width for subsequent quasi-optical link design and provide high-speed communication.

[0017] Furthermore, the beam focusing device includes: an ellipsoidal reflector with a high-precision surface, using the ABCD beam transfer matrix and beam matching conditions of the ellipsoidal reflector ,in is the distance from the incident focus to the reflection point, The curvature radius of the incident beam is used to converge and fold the beams of each channel while maintaining a small distortion to achieve controllable system volume.

[0018] Furthermore, the beam separation device includes: 45GHz and 220GHz bandpass frequency selective surfaces and a linear polarization grating; the bandpass frequency selective periodic surface based on Floquet's theorem is used to achieve separation and synthesis of multi-frequency beams, and the linear polarization grating is used to achieve separation and synthesis of dual-polarization beams, thereby doubling the beam channels.

[0019] Furthermore, the beam scanning device includes: a large-aperture reflector antenna based on a Cassegrain antenna structure, which utilizes an equivalent feed source with a focus shift of less than 4 cm combined with a physical optics simulation method to achieve a beam scanning angle greater than or equal to 20 degrees.

[0020] The present invention also provides an optimization design method for a multi-frequency, multi-polarization, wide-beam scanning base station system, comprising the following steps:

[0021] S1. Measure the beam waist width and equivalent beam waist position of the front-end quasi-optical link output beam as the equivalent Gaussian feed source of the reflector antenna;

[0022] S2. Expand the main reflector busbar with a finite term using Fourier series. In the present invention, the first 11 expansion coefficients are sufficient to meet the simulation accuracy.

[0023] S3. Use programming languages ​​to implement modeling and simulation in electromagnetic simulation software, greatly improving the simulation optimization efficiency of the system;

[0024] S4. Setting a fitness function based on the target scanning angle, equivalent feed position, and equivalent beam waist width. The fitness function mainly depends on the energy proportion of the target scanning angle interval of the E-plane pattern obtained by simulation analysis.

[0025] S5. Utilize genetic algorithms and electromagnetic simulation analysis to continuously adjust Fourier expansion coefficients. Genetic algorithms are heuristic algorithms that solve optimization problems by simulating biological evolution. Based on the fundamental principles of natural selection and genetics, they simulate the natural evolutionary process to gradually select superior genes from the population, achieving optimization goals.

[0026] S6. When the fitness function reaches the minimum value, the optimization stops and the optimized expansion coefficient is retained. At this time, the shape optimization ends and all steps of the optimization design are completed.

[0027] The advantages and beneficial effects of the present invention are as follows:

[0028] The present invention has a wide bandwidth, covering all available frequency bands for mobile communications in the range of 24.25GHz to 226GHz, greatly expanding the bandwidth of existing base stations; the loss is low, and the front-end feeding system adopts a quasi-optical solution, and electromagnetic waves propagate between free space and metal reflective surfaces; the beam scanning angle is large, and the contradiction between the shielding effect of the sub-reflective surface and the beam scanning angle is alleviated by using a genetic algorithm to optimize the shape of the reflective surface, and a beam scanning angle greater than or equal to 20 degrees is achieved through a small defocus movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of a multi-frequency, multi-polarization, wide-beam scanning base station system according to the present invention;

[0030] Figure 2 is a cross-sectional view of a conical corrugated horn;

[0031] FIG3 is a schematic diagram of a periodic unit of a frequency selective surface;

[0032] Figure 4 is a schematic diagram of the linear polarization grid;

[0033] FIG5 is a flow chart of the steps for designing an ellipsoidal surface;

[0034] FIG6 is a flow chart of the reflection surface shaping optimization;

[0035] Figure 7 is a schematic diagram of the results before and after shape optimization.

[0036] The meanings of the reference numerals in the figure are: 1 is H-polarized 100 GHz feed, 2 is H-polarized 220 GHz feed, 3 is H-polarized 45 GHz feed, 4 is V-polarized 220 GHz feed, 5 is V-polarized 100 GHz feed, 6 is V-polarized 45 GHz feed, 7 is H-polarized 100 GHz feed converging reflector group, 8 is H-polarized 220 GHz feed converging reflector group, 9 is H-polarized 45 GHz feed converging reflector group, 10 is V-polarized 100 GHz feed converging reflector group Mirror group, 11 is the V-polarization 220GHz feed converging reflector group, 12 is the V-polarization 45GHz feed converging reflector group, 13 is the H-polarization 220GHz bandpass frequency selective surface, 14 is the H-polarization 45GHz bandpass frequency selective surface, 15 is the V-polarization 220GHz bandpass frequency selective surface, 16 is the V-polarization 45GHz bandpass frequency selective surface, 17 is the V-polarization multi-beam converging mirror, 18 is the H-polarization multi-beam converging mirror, 19 is the linear polarization grating, and 20 is the terminal reflector antenna. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0038] The following further illustrates how the system is designed with reference to the accompanying drawings and specific implementations.

[0039] The basic principle structure of the present invention is shown in Figure 1. The feed sources use 45GHz, 100GHz and 220GHz conical corrugated horns to provide the initial Gaussian beam. The feed sources include H-polarized 100GHz feed 1, H-polarized 220GHz feed 2, H-polarized 45GHz feed 3, V-polarized 220GHz feed 4, V-polarized 100GHz feed 5, and V-polarized 45GHz feed 6. The waist sizes and positions of the Gaussian beams of the three 45GHz, 100GHz and 220GHz conical corrugated horns are given below. Only by clarifying the waist size and position of the feed source Gaussian beam can the Gaussian beam parameters such as the beam radius and curvature radius at each position of the quasi-optical link system be accurately calculated. After emitting Gaussian beams, H-polarized 100 GHz feed 1, H-polarized 220 GHz feed 2, H-polarized 45 GHz feed 3, V-polarized 220 GHz feed 4, V-polarized 100 GHz feed 5, and V-polarized 45 GHz feed 6 enter a reflector system, comprising H-polarized 100 GHz feed converging reflector group 7, H-polarized 220 GHz feed converging reflector group 8, H-polarized 45 GHz feed converging reflector group 9, V-polarized 100 GHz feed converging reflector group 10, V-polarized 220 GHz feed converging reflector group 11, and V-polarized 45 GHz feed converging reflector group 12. This reflector system folds, converges, and transforms the incoming Gaussian beams, ensuring that the outgoing Gaussian beam parameters meet subsequent design specifications. The reflector design method and steps are described below. The 100 GHz and 220 GHz beams pass through H-polarized 100 GHz feed converging reflector group 7, H-polarized 220 GHz feed converging reflector group 8, V-polarized 100 GHz feed converging reflector group 10, and V-polarized 220 GHz feed converging reflector group 11 before entering a 220 GHz bandpass frequency selective surface. The two transmission paths are then combined using the 220 GHz bandpass frequency selective surface. This path beam then joins the 45 GHz beam, which has passed through H-polarized 45 GHz feed converging reflector group 9 and V-polarized 45 GHz feed converging reflector group 12, and enters a 45 GHz bandpass frequency selective surface. The three frequency beam transmission paths are then combined using the 45 GHz bandpass frequency selective surface. The beams then enter a linear polarization grid, combining the H-polarized and V-polarized beam paths, doubling the number of channels. Finally, the beams of all frequency channels and all polarization channels are combined at the same location and in the same direction and fed uniformly into the reflector antenna. Ultimately, the reflector antenna achieves high-gain beam scanning.

[0040] The following describes the transmission process of the 6-channel signal in detail: The H-polarized 100 GHz signal is transmitted by the H-polarized 100 GHz feed 1, then enters the H-polarized 100 GHz feed converging reflector group 7, then passes through the H-polarized 220 GHz bandpass frequency selective surface 13 and the H-polarized 45 GHz bandpass frequency selective surface 14, then passes through the H-polarized multi-beam converging mirror 18, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The H-polarized 220 GHz signal is transmitted by the H-polarized 220 GHz feed 2, then enters the H-polarized 220 GHz feed converging reflector group 8, then passes through the H-polarized 220 GHz bandpass frequency selective surface 13 and the H-polarized 45 GHz bandpass frequency selective surface 14, then passes through the H-polarized multi-beam converging mirror 18, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The H-polarized 45 GHz signal is transmitted through the H-polarized 45 GHz feed 3, then enters the H-polarized 45 GHz feed converging reflector group 9, then passes through the H-polarized 45 GHz bandpass frequency selective surface 14, then passes through the H-polarized multi-beam converging mirror 18, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The V-polarized 100 GHz signal is transmitted through the V-polarized 100 GHz feed 5, then enters the V-polarized 100 GHz feed converging reflector group 10, then passes through the V-polarized 220 GHz bandpass frequency selective surface 15 and the V-polarized 45 GHz bandpass frequency selective surface 16 in sequence, then passes through the V-polarized multi-beam converging mirror 17, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The V-polarized 220GHz signal is transmitted through the V-polarized 220GHz feed 4, then enters the V-polarized 220GHz feed converging reflector group 11, then passes through the V-polarized 220GHz bandpass frequency selective surface 15 and the V-polarized 45GHz bandpass frequency selective surface 16 in sequence, then passes through the V-polarized multi-beam converging mirror 17, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The V-polarized 45GHz signal is transmitted through the V-polarized 45GHz feed 6, then enters the V-polarized 45GHz feed converging reflector group 12, then passes through the V-polarized 45GHz bandpass frequency selective surface 16, then passes through the V-polarized multi-beam converging mirror 17, and finally passes through the linear polarization grating 19 to feed the terminal reflector antenna 20. The overall size of the front-end quasi-optical link panel is 30cm 40cm.

[0041] The basic structure of the conical corrugated horn is shown in Figure 2. The conical corrugated horn antenna can provide an axisymmetric aperture field distribution, which is the basis for coupling with the Gaussian transmission mode. In quasi-optical systems, conical corrugated horns are often used as feed sources, which can radiate an approximate Gaussian beam. The depth of the mode conversion slot is determined by Gradually change to , then maintain unchanged, among which is the center wavelength of the feed source. In Figure 2, L1 is the length of the mode conversion section, L2 is the length of the mode maintaining section, L3 is the length of the Gaussian profile section, L is the length of the conical corrugated horn, r is the radius of the feeding circular waveguide, d is the corrugated groove depth, w is the groove width, t is the wave tooth width, a is the horn mouth radius, and α is the mouth angle. The solution of the paraxial wave equation consists of a series of Gaussian modes, which are orthogonal to each other, so they can be used as an orthogonal basis for the expansion of the mouth field. Therefore, the electric field of the paraxial light beam perpendicular to the optical axis can always be expanded to the superposition of these modes. Usually, the original electric field can be well expanded with fewer Gaussian modes. In some cases, only the Gaussian basis modes can provide a very high coupling coefficient. In the conical corrugated horn, When the near-field energy distribution is coupled with the Gaussian base mode at a rate of up to 98%, it can provide a stable phase center and beam width. The waist of the radiated Gaussian beam is The radius of the bell mouth is The parameters of the horn at each frequency are detailed in Table 1. In Table 1, f is the center frequency of the conical corrugated horn.

[0042] Table 1

[0043]

[0044] The far-field E-plane and H-plane far-field patterns of the 45GHz, 100GHz, and 220GHz conical corrugated horns are roughly the same, with a high degree of energy concentration in the main lobe. The E-plane beam is wide with low sidelobes, while the H-plane beam is narrow with high sidelobes. The 45GHz conical corrugated horn has a maximum gain of 20.2dBi on the E-plane far-field pattern and a 3dB beamwidth of 19.7deg; the H-plane far-field pattern has a maximum gain of 20.2dBi with a 3dB beamwidth of 18.2deg. The 100GHz conical corrugated horn has a maximum gain of 20.2dBi on the E-plane far-field pattern and a 3dB beamwidth of 19.7deg; the H-plane far-field pattern has a maximum gain of 20.2dBi with a 3dB beamwidth of 18.2deg. The 220GHz conical corrugated horn has a maximum far-field gain of 20.2dBi on the E-plane and a 3dB beamwidth of 19.7deg. The H-plane has a maximum far-field gain of 20.2dBi and a 3dB beamwidth of 18.4deg. The horn phase center and beam waist width are shown in Table 2.

[0045] Table 2

[0046]

[0047] Table 2 lists the phase center and beam waist widths of the 45 GHz, 100 GHz, and 200 GHz feed horns. It can be seen that the phase center and the horn's aperture are nearly aligned. This design of the Gaussian feed horn greatly facilitates the system-level design of quasi-optical links. The reason for the non-complete overlap between the phase center and the horn's aperture is that the energy coupling coefficient between the Gaussian base mode and the conical corrugated horn is not 100%.

[0048] Figure 3 shows the periodicity of the frequency selective surface. Using Floquet's periodic boundary theory, the frequency response characteristics of the frequency selective surface can be quickly and accurately calculated using the finite-difference time-domain (FDTD) algorithm. In electromagnetics, Floquet's theorem can be generalized to state that, in a stable transmission mode, the field at one section differs from the field at another section separated by a certain spatial period by only a complex constant. Table 3 lists the detailed parameters of the frequency selective surface (FSS). Ts is the side length of the periodic unit, H1 is the length of the short side, H2 is the length of the long side, R is the radius of the central disk, and Hs is the distance between the FSS layers.

[0049] Table 3

[0050]

[0051] In quasi-optical link systems, considering the optical path layout and the placement of components, the beam is generally not normally incident on the frequency selective surface. The TE wave is set as the excitation signal to be incident on the 45GHz and 220GHz frequency selective surfaces, and the incident angles of 0deg, 15deg, 30deg and 45deg are set in the simulation program in sequence to calculate their reflection coefficient and transmission coefficient. The double-layer frequency selective surface structure provides two resonance points with a close distance, which effectively increases the bandwidth. The -10dB bandwidth of the 45GHz frequency selective surface is about 5GHz, and the -10dB bandwidth of the 220GHz frequency selective surface is about 30GHz. As the incident angle increases, the reflection coefficient at the center of the passband increases slightly, but is still below -10dB, showing good large incident angle performance.

[0052] The principle diagram of the linear polarization grid is shown in Figure 4. The linear polarization grid can separate or synthesize vertical polarization beams and horizontal polarization beams, thereby realizing the design requirements of multi-polarization. Generally, the incident beam is a vertically polarized beam and a horizontally polarized beam, the transmitted beam is a vertically polarized beam, and the reflected beam is a horizontally polarized beam. In general, 、 The substrate-free linear polarization grid metal wire can meet the quasi-optical link indicators. Where c is the metal line width and g is the metal line spacing.

[0053] The design steps of the ellipsoidal metal reflector are shown in Figure 5. First, the outgoing beam parameters are determined based on the incident beam parameters. When designing a reflector in a quasi-optical link system, the angle between the incident beam and the outgoing beam is usually determined. is a constant value. At the same time, the working wavelength of the incident beam (i.e. feed center wavelength), confocal distance , waist and the distance between the beam waist and the ellipsoidal mirror are all known. If the output beam waist is , then according to the formula:

[0054]

[0055] The equivalent focal length of the ellipsoidal mirror can be calculated , and then according to the following formula:

[0056]

[0057] Find the distance between the waist of the outgoing beam and the ellipsoidal mirror .

[0058] Secondly, the specific parameters of the ellipsoid are determined based on the incident beam and the outgoing beam. When the incident beam and the outgoing beam match the ellipsoid mirror, ,in is the distance from the incident focus to the reflection point, is the incident beam curvature radius. Finally, according to The design of the reflecting surface can be completed by intercepting the ellipsoidal mirror according to the principle. is the beam radius at the reflecting surface. When the intercepting mirror radius is greater than twice the beam radius, 99.99% of the beam energy can be included.

[0059] After passing through the quasi-optical link system, the three-channel beams did not diverge, and the beam waists were converged to the same position, with good phase maintenance, which greatly facilitated the subsequent reflector antenna design.

[0060] The following further illustrates how the system is optimized with reference to the accompanying drawings and specific implementations.

[0061] S1. Measure the beam waist width and equivalent beam waist position of the front-end quasi-optical link output beam, see Table 4 (Output Beam Parameters).

[0062] Table 4

[0063]

[0064] S2. Use Fourier series to expand the main reflector busbar into finite terms, where: to is the Fourier expansion coefficient, see Table 5 (Fourier expansion coefficient table).

[0065] Table 5

[0066]

[0067] S3. Implement electromagnetic modeling in electromagnetic simulation software using programming languages;

[0068] S4, setting the fitness function according to the target scanning angle, equivalent feed position and equivalent beam waist width;

[0069] S5. Utilize genetic algorithms and electromagnetic simulation analysis to continuously adjust the Fourier expansion coefficients, as shown in FIG6 , including: using a dedicated program to control electromagnetic simulation software to calculate the far-field pattern; calculating the fitness function value based on the far-field pattern; feeding the fitness function value back into the genetic algorithm; adjusting the expansion coefficients based on the genetic algorithm; and using a dedicated program to recalculate the far-field pattern based on the expansion coefficients, continuously looping the optimization.

[0070] S6. When the fitness function reaches its minimum value, the optimization stops and the optimized expansion coefficient is retained. The optimized expansion coefficient is simulated again to verify that the beam scanning angle is effectively doubled, as shown in Figure 7.

Claims

1. A multi-frequency and multi-polarization wide-beam scanning base station system, characterized in that It includes a beam generation device, a beam convergence device, a beam separation device, and a beam scanning device; The beam generation device is used to radiate an approximate Gaussian beam with a broadband conical horn feed; The beam convergence device utilizes the beam convergence characteristic of an ellipsoidal mirror to fold and converge multi-beam channels; The beam separation device separates multi-channel beams through the beam separation characteristics of a frequency selective surface and a linear polarization grid; The beam scanning device realizes wide-angle beam scanning through a large-aperture reflector antenna with optimized shaping.

2. The multi-frequency multi-polarization wide-beam scanning base station system according to claim 1, wherein The beam generation device includes: 45 GHz, 100 GHz, and 220 GHz conical corrugated horns, and the depth of the mode conversion section wave slot gradually changes from to , where is the center wavelength of the feed; and the waist of the radiated Gaussian beam is , the radius of the horn aperture is , when the near-field energy distribution and the coupling degree of the Gaussian fundamental mode reach 98%, which can provide a stable phase center and beam width for subsequent quasi-optical link design and provide high-rate communication.

3. The multi-frequency and multi-polarization wide-beam scanning base station system according to claim 1, characterized in that, The beam converging device includes an ellipsoidal mirror with a high-precision surface, and uses the ABCD beam transfer matrix of the ellipsoidal mirror and the beam matching condition , where is the distance from the incident focus to the reflection point, is the curvature radius of the incident beam, folding and converging the beams of each channel while maintaining a small distortion amount, and realizing the controllability of the system volume.

4. A multi-frequency multi-polarization wide-beam scanning base station system according to claim 1, characterized in that, The beam separation device includes a 45GHz and 220GHz band-pass frequency selective surface and a linear polarization grid; the separation and synthesis of multi-frequency beams are realized through the band-pass frequency selective periodic surface based on Floquet's theorem, and the separation and synthesis of dual-polarization beams are realized through the linear polarization grid, doubling the beam channels.

5. A multi-frequency multi-polarization wide-beam scanning base station system according to claim 1, characterized in that, The beam scanning device includes a large-aperture reflector antenna with a Cassegrain antenna structure as the prototype, and realizes a beam scanning angle greater than or equal to 20deg by combining the defocus movement of an equivalent feed less than 4cm with the physical optics simulation method.

6. An optimization design method for a multi-frequency and multi-polarization wide-beam scanning base station system according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Measure the waist width and equivalent waist position of the output beam of the front-end quasi-optical link; S2. Expand the main reflector generatrix with a finite number of terms using Fourier series; S3. Implement modeling and simulation in an electromagnetic simulation software using a programming language; S4. Set a fitness function according to the target scanning angle, equivalent feed position, and equivalent waist width; S5. Continuously adjust the Fourier expansion coefficients using a genetic algorithm and electromagnetic simulation analysis; S6. Stop the optimization when the fitness function obtains the minimum value, and retain the optimized Fourier expansion coefficients.

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