A high-polarization purity beamforming method based on auxiliary array polarization cancellation

Abstract

The application discloses a cross-polarization cancellation high-polarization-purity beam forming method based on a rotating auxiliary array, belongs to the technical field of array antennas, and aims to solve the problems of low array antenna beam polarization purity, complex cross-polarization suppression algorithm and cross-polarization deterioration in large-angle scanning. The method is applied to an array antenna containing a main array plane and an auxiliary array plane, first, the cross-polarization of the central unit of the main array, the main polarization pattern value is taken as a reference, the total number of main array units is combined to calculate the main array cross-polarization field amplitude and determine the number of auxiliary units; then, the auxiliary array plane is arranged on the side of the main array, and the auxiliary array unit is 90 DEG polarized rotation relative to the main array unit; finally, the auxiliary array unit excitation amplitude is calculated, and the main beam pointing phase is matched, so that the cross-polarization field amplitudes of the two are the same, the phases are opposite, and the high-polarization-purity main beam is formed by superposition. The application has low cost, strong engineering realizability, good compatibility and adaptability to large-angle scanning, and is suitable for fields such as radars and communications.

Description

Technical Field

[0001] This invention belongs to the field of array antenna technology, specifically relating to a method for forming a high polarization purity beam based on the cross-polarization cancellation of a rotating auxiliary array, and more specifically, relating to a method and corresponding array antenna structure for achieving precise cross-polarization cancellation of the main array using a small number of rotating polarization auxiliary units, thereby forming a high polarization purity beam. Background Technology

[0002] With the rapid development of mobile communication, high-precision radar detection, and integrated satellite communication, array antennas, as the core front-end devices of wireless systems, are facing increasingly complex electromagnetic environments and ever-increasing demands for target polarization sensing and anti-interference capabilities. High-polarization-purity vector beamforming technology has become one of the core research directions in the field of array antenna beam synthesis.

[0003] Based on publicly available patents, researchers have conducted some studies on array and polarization characteristic modulation. However, these studies mainly focus on signal processing techniques during signal reception by the array antenna, such as polarization matching or interference suppression through back-end algorithms. Existing solutions do not yet address technical approaches for pre-implementing high-polarization-purity beams at the transmitting front-end, for example:

[0004] Chinese invention patent (CN121028006A) discloses a method for suppressing main lobe suppression polarization agility interference. Targeting main lobe suppression interference with dynamically changing polarization parameters, this method constructs a transient polarization projection vector (IPPV) of the orthogonal polarization received signal based on the orthogonal polarization received signal of a dual-polarization radar. The echo signal is processed in segments, and interference is suppressed using a polarization cancellation algorithm. This is a signal processing technology based on the received signal and does not involve beam control at the transmitting front end of the array antenna.

[0005] Chinese invention patent (CN120409252A) discloses a radar anti-sidelobe interference method based on electronic reconnaissance. This method performs polarization filtering on the main beam by configuring an electronic reconnaissance channel, employs an integrated design of electronic reconnaissance and jamming countermeasures, and uses electronic reconnaissance technology to obtain jamming-related information, thereby completing auxiliary channel selection and adaptive optimal weight calculation to improve the radar's anti-sidelobe interference performance. This method mainly focuses on sidelobe cancellation, without addressing the main lobe region or considering beam polarization purity.

[0006] In summary, in order to solve the technical problems faced by the above-mentioned background technology, this invention proposes a high polarization purity beamforming method based on polarization cancellation. Summary of the Invention

[0007] This invention aims to solve the technical problems of low beam polarization purity of array antennas, high cost, complex algorithms, poor adaptability, and difficulty in stably forming high polarization purity beams when the cross polarization of the unit deteriorates in large-angle scanning scenarios in the existing technology. It provides a cross polarization cancellation and high polarization purity beamforming method with simple structure, strong engineering feasibility, good compatibility, and adaptability to large-angle scanning scenarios.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a method for cross-polarization cancellation high-polarization purity beamforming based on a rotating auxiliary array, applied to an array antenna including a main array and an auxiliary array. The main array is composed of conventionally arranged radiating elements and undertakes the core functions of main beamforming and energy radiation. The auxiliary array is a rotating auxiliary array, composed of radiating elements far fewer in number than the main array. All radiating elements of the auxiliary array are polarized and rotated 90° relative to the radiating elements of the main array. There is no need to design complex elements; the compensation electric field signal for cross-polarization cancellation can be generated simply by physically rotating the array elements, thereby achieving high-polarization purity beamforming in conjunction with the main array.

[0009] This invention uses field cancellation as its core to suppress cross-polarization, thereby forming a high-polarization-purity beam. Without changing the original arrangement and working state of the main array or affecting the normal formation of the main beam, the radiation element of the rotating auxiliary array generates an electric field signal with the same amplitude and opposite phase to the cross-polarization component of the main array at the target beam pointing position. Combined with a simple weighted matching method, it achieves precise cancellation of cross-polarization at the beam pointing position, ultimately forming a high-polarization-purity main beam.

[0010] The specific method for cross-polarization cancellation and high-polarization-purity beamforming includes the following steps:

[0011] The first step is to obtain the cross-polarization pattern value of the central element of the main array. Based on the cross-polarization pattern value of the central element, and combined with the total number of radiating elements of the main array, an equivalent calculation is performed to obtain the cross-polarization field amplitude of the entire main array at the target beam direction. At the same time, based on the main polarization pattern value of the central element of the main array, the number of auxiliary elements required to achieve effective cancellation is calculated to ensure that the cancellation capability of the auxiliary elements matches the cross-polarization field of the main array.

[0012] The second step involves constructing a small auxiliary array based on the number of auxiliary units determined in the first step. This small auxiliary array is then placed next to the main array, and all units of the auxiliary array are rotated 90° relative to the radiating units of the main array. This ensures that the rotating auxiliary array can generate a compensating electric field signal that matches the cross-polarization components of the main array, thus providing support for cross-polarization cancellation and high-polarization-purity beamforming.

[0013] The third step involves calculating the excitation amplitude of each radiating element of the rotating auxiliary array based on the equivalent calculation obtained in the first step. This ensures that the electric field generated by the rotating auxiliary array matches the amplitude of the cross-polarization field of the main array. Simultaneously, phase matching is performed using the array factor according to the beam direction of the main beam. This ensures that the electric field generated by the rotating auxiliary array and the cross-polarization field of the main array form a superposition effect with the same amplitude but opposite phase at the target beam direction. This achieves precise cancellation of cross-polarization at the beam direction, ultimately enabling the main array to form a main beam with high polarization purity and suppressing the beam cross-polarization component to an extremely low level.

[0014] The high polarization purity beamforming method and corresponding array antenna structure of this invention do not require the design of complex elements, nor do they require complex adaptive algorithms and multi-domain joint optimization. Only the elements of the array itself need to be physically rotated, resulting in extremely low hardware costs and computational overhead, and strong engineering feasibility. At the same time, due to the small number of rotation auxiliary elements, it not only has good compatibility with existing arrays, but can also be directly applied to the beam optimization of existing arrays. In the application scenario of large-angle scanning arrays, even if there is a large-angle cross-polarization deterioration of elements, it can still stably achieve cross-polarization cancellation and form a high polarization purity beam. It is suitable for various electronic systems such as radar and communication that have a clear requirement for high polarization purity beams, and has outstanding practicality and wide promotion value.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. A composite structure consisting of a main array and a small number of rotating polarization auxiliary arrays is adopted. Without the need for complex units and algorithms, the core is field cancellation. The weighting coefficient is calculated solely by the amplitude of the beam pointing direction pattern. This enables precise cancellation of cross-polarization at the beam pointing direction. The computation is small, the implementation is simple, and the real-time performance is strong. It can significantly improve polarization purity and effectively reduce hardware costs.

[0017] 2. Through the precise calculation of the number of auxiliary elements and the edge layout of the auxiliary array design, it is not only applicable to normal beam scenarios, but also to large-angle scanning arrays. It can still stably achieve cross-polarization suppression in scanning scenarios where the cross-polarization of elements deteriorates at large angles. It has strong compatibility with existing arrays, can be directly ported and applied, and has a wide range of applications and strong practicality. Attached Figure Description

[0018] To more clearly and completely illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly described below. Obviously, the following drawings are only some embodiments of the present invention. For those skilled in the art, other drawings and technical solutions can be obtained based on these drawings without creative effort.

[0019] Figure 1 Here is the algorithm flowchart;

[0020] Figure 2 This is a schematic diagram of a composite array as shown in the embodiment.

[0021] Figure 3 This is an example of a high-polarization-purity beam pattern in the normal direction;

[0022] Figure 4 This is an example of a high-polarization-purity beam pattern under large-angle scanning conditions; Detailed Implementation

[0023] The present invention will be further described in detail and completely below with reference to specific embodiments and core formulas. The following embodiments are based on the core technical solution of the present invention, providing detailed implementation processes and core mathematical models; however, the scope of protection of the present invention is not limited to the following embodiments. The present invention mainly introduces a method for forming high polarization purity beams based on a rotating auxiliary array with cross-polarization cancellation. This method includes the following steps:

[0024] First, the array structure proposed in this invention consists of a main array and an auxiliary array. The main array is composed of several antenna elements arranged in a conventional array configuration. The spacing between the elements is determined based on the operating frequency band and beam coverage area to ensure that the main array has a stable radiation pattern, good beam symmetry, and controllable sidelobe characteristics within the operating area. The main array undertakes the core functions of beamforming and energy radiation. Its arrangement, feeding structure, and excitation method maintain the typical design of traditional single-polarization arrays, without requiring structural changes or parameter reconfiguration due to the introduction of auxiliary channels.

[0025] The auxiliary array consists of far fewer antenna elements than the main array, using the same elements as the main array. To avoid grating lobes due to excessive spacing between auxiliary elements and to ensure that the radiated beamwidth of the auxiliary array matches that of the main array, the auxiliary array adopts a compact and centralized layout. The auxiliary elements are arranged in a continuous area at the edge of the main array, ensuring that the spacing between the auxiliary elements meets the grating lobe-free constraint condition of conventional arrays. This layout provides a compensation field with sufficient amplitude and matching pattern for cross-polarization cancellation without occupying the core radiating aperture of the main array.

[0026] The number of auxiliary elements is determined based on the cross-polarization radiation intensity of the main array at the target beam direction. This value is based on the radiation pattern of the central element of the main array surface, and the main polarization pattern value of this element can be obtained through far-field testing or electromagnetic simulation. The cross-polarization pattern value is The cross-polarization pattern of the main array at the beam pointing direction. for:

[0027]

[0028] in To motivate, For amplitude, Phase; wave number Wavelength; The position of the element in the Cartesian coordinate system. Let be the propagation vector of the wave.

[0029] To avoid excessive hardware costs and space occupation due to too many auxiliary units, or insufficient cancellation effect due to too few units, and to ensure the completeness of cancellation, the minimum number of auxiliary units is determined. The following relationship must be satisfied:

[0030]

[0031] in, The rounding up operation ensures that the auxiliary array can provide a sufficiently canceling radiation field.

[0032] Based on the minimum number of auxiliary units The auxiliary elements are arranged into a planar array. All radiating elements of the auxiliary array are rotated 90° relative to the radiating elements of the main array. The specific rotation direction can be flexibly adjusted according to the polarization direction of the main array (e.g., if the main array elements are horizontally polarized, the auxiliary array elements are rotated to vertical polarization). This ensures that the polarization direction of the auxiliary array radiating elements is consistent with the cross-polarization direction of the main array, thereby generating a compensated electric field signal that matches the cross-polarization component of the main array. The constructed auxiliary array is placed beside the main array, preferably at its edge. This layout reduces interference from the auxiliary array to the main array's radiation field, saves space, and facilitates compatibility with existing arrays. During the arrangement, the element spacing is set to half a wavelength to avoid excessive spacing that prevents the compensated electric field signal generated by the auxiliary array from effectively superimposing with the cross-polarization field of the main array, or excessive spacing that causes electromagnetic coupling interference between the main and auxiliary arrays, affecting beamforming quality. At this point, the main polarization radiation field of the auxiliary array is...

[0033]

[0034] Similar to the preceding expressions, in which To motivate, For amplitude, For phase;

[0035] After completing the array structure and polarization configuration, this invention uses closed-loop calculations based on the radiation pattern data at the target pointing location to obtain the excitation amplitude and phase of the auxiliary array surface, thereby achieving precise cancellation. This is achieved by using the positions requiring cancellation... The amplitude of the cross-polarization of the main array surface at the location With the main polarization amplitude of the auxiliary array And thereby determine the element excitation of the auxiliary array.

[0036]

[0037] The auxiliary array proposed in this patent has all elements with the same amplitude, that is...

[0038]

[0039] get

[0040]

[0041] In this equation, the negative sign ensures that the auxiliary array generates electric field components with the same cross-polarization amplitude but opposite phase as the main array, so that they cancel each other out after being superimposed in space. Simultaneously, to ensure that the electric field of the auxiliary array acts at the beam pointing direction, the phase of the auxiliary array remains synchronized with that of the main array. Therefore, the element excitation of the auxiliary array is:

[0042]

[0043] Applying this excitation to the auxiliary array can achieve zeroing of the cross-polarization at the beam pointing point, significantly improving the beam polarization purity.

[0044] Furthermore, due to the compact layout of the auxiliary array and its compliance with grating lobe-free constraints, the overall radiation pattern remains free of distortion and grating lobes. Simultaneously, the rotational polarization setting ensures that the auxiliary array only affects the cross-polarization components, minimizing its impact on the main polarization radiation, thus maintaining stable performance in terms of main polarization gain and beamwidth. Moreover, thanks to the cross-polarization cancellation at the beam pointing point, cross-polarization in other regions within the main lobe is also suppressed. This invention requires no complex algorithms, no additional unit design, and no multi-port coupled solution; high polarization purity beams can be achieved solely through structural layout and closed-loop excitation. The entire process is as follows: Figure 1 As shown.

[0045] Given a numerical example, the main array is a 224-element chamfered array with half-wavelength element spacing. Calculate the minimum number of auxiliary elements based on the radiation pattern values. Following step 2, the rotated units are placed as auxiliary array surfaces in the red area shown in the diagram. The overall array layout structure is as follows. Figure 2 As shown. Simultaneously, the required excitation for the auxiliary array elements is calculated based on the pointing position of the synthesized beam. Here, the excitation is given when the beam direction is the normal direction. and scanned The beamforming results are as follows: Figure 3 and Figure 4 As shown. In addition, the beam pattern without the method of this patent was compared. It is clear that the method of this patent suppresses beam cross-polarization and improves beam polarization purity without affecting the radiation characteristics of the main array, thus verifying its effectiveness.

Claims

1. A method for high polarization purity beamforming based on a rotating auxiliary array with cross-polarization cancellation, characterized in that, An array antenna comprising a main array and an auxiliary array, wherein the main array is composed of conventionally arranged radiating elements and the auxiliary array is composed of a much smaller number of radiating elements than the main array, the method includes the following steps: S1. Obtain the main polarization pattern value and cross-polarization pattern value of the main array center element at the target beam direction. Based on the cross-polarization pattern value, and combined with the total number of radiating elements of the main array and the excitation parameters of the main array elements, calculate the cross-polarization field amplitude of the main array at the target beam direction. At the same time, based on the main polarization pattern value and the cross-polarization field amplitude of the main array, determine the minimum number of auxiliary elements required to achieve effective cross-polarization cancellation. S2. Select radiating elements with the same specifications as the main array elements, construct auxiliary arrays according to the determined minimum number of auxiliary elements, arrange the auxiliary arrays in the edge region of the main array, the spacing between auxiliary elements satisfies the no-lobe constraint condition, and all auxiliary array radiating elements are polarized and rotated 90° relative to the main array radiating elements. S3. Based on the amplitude of the main array cross-polarization field at the target beam pointing direction and the amplitude of the auxiliary array main polarization radiation field, the excitation amplitude and phase parameters of each element of the auxiliary array are obtained through closed-form calculation. The excitation amplitude and phase parameters are applied to the auxiliary array so that the electric field generated by the auxiliary array and the main array cross-polarization field form a superposition with the same amplitude and opposite phase at the target beam pointing direction, thereby achieving cross-polarization cancellation and enabling the main array to form a main beam with high polarization purity.

2. The method according to claim 1, characterized in that, In step S1, the main polarization pattern value and cross polarization pattern value of the central element of the main array are obtained in advance by far-field testing or electromagnetic simulation.

3. The method according to claim 1, characterized in that, In step S1, the minimum number M of auxiliary units satisfies the following relationship: ； in, The main array is in the target beam direction Cross-polarization field at the location ,in To motivate, For amplitude, Phase; wave number Wavelength; The position of the element in the Cartesian coordinate system. The propagation vector of the wave; This refers to the main polarization pattern value of the central element of the main array at the target's direction. This is a rounding up operation.

4. The method according to claim 1, characterized in that, In step S2, the auxiliary array is constructed by rotating the conventional radiating elements by 90°, so that the auxiliary array generates a compensating electric field that matches the cross-polarization component of the main array only at the target beam direction, and has virtually no impact on the main polarization radiation. The core idea is polarization cancellation. ； in, The main polarization radiation field of the auxiliary array ; Similar to the preceding expression, in which To motivate, For amplitude, Phase; wave number Wavelength; To help locate the array elements in the Cartesian coordinate system, is the propagation vector of the wave.

5. The method according to claim 1, characterized in that, In step S3, the excitation amplitude of each element of the auxiliary array is the same, i.e., in clause 4. Written as ； excitation Calculated using the following formula: ； in, The cross-polarization field value of the main array surface, The primary polarization field value for the auxiliary array; wavenumber Wavelength; To help locate the array elements in the Cartesian coordinate system, The amplitude is the result of the array field value matching, and the phase is determined according to the direction of the main beam.

6. The method according to claim 1, characterized in that, In step S3, the auxiliary array adopts a compact and centralized layout, and the unit spacing is controlled at half a wavelength to avoid grating lobes and ensure that the array pattern after cancellation is distortion-free and the sidelobes are controllable.

7. The method according to any one of claims 1-6, characterized in that, The method is applicable to large-angle scanning array applications. During large-angle scanning, high-polarization-purity beamforming can also be stably achieved based on the amplitude of the cross-polarization field of the main array and the excitation amplitude and phase parameters of the auxiliary array.

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