Antenna pattern reconstruction method

Abstract

The invention discloses an antenna pattern reconstruction method, which relates to the technical field of wireless communication and antenna testing, and comprises the following steps of: selecting two measurement distances in a near-field area, determining a probe angle range and a probe angle interval, and measuring amplitude data of an antenna in a single tangent plane direction to obtain an antenna near-field amplitude pattern on the single tangent plane; copying the antenna near-field amplitude directional diagrams at the two measurement distances measured in the single tangent plane direction to azimuth angles in other spherical coordinate systems, and obtaining 3D antenna near-field amplitude directional diagrams on two spherical surfaces; recovering phases by utilizing the 3D antenna near-field amplitude directional diagrams on the two spherical surfaces to obtain a plurality of near-field directional diagrams of the to-be-tested equipment on the two spherical surfaces; and calculating an antenna far-field pattern of the to-be-tested equipment according to the plurality of near-field patterns of the to-be-tested equipment on the two spherical surfaces. According to the method, system parameters are optimized, so that the measurement cost and time are remarkably reduced, and the method is suitable for rapid air interface (OTA) testing of a 5G large-scale MIMO base station.

Description

Technical Field

[0001] This invention relates to the field of wireless communication and antenna testing technology, and in particular to an antenna pattern reconstruction method. Background Technology

[0002] Massive Multiple Input Multiple Output (MIMO) has become one of the key radio technologies for 5G and future radio systems. Meanwhile, the trend of using larger antenna array configurations will continue in future wireless systems. The far-field (FF) antenna radiation pattern is a fundamental antenna metric that can be obtained through various solutions, such as plane wave generators, compact field, field transform, and mid-field (MF) solutions. Two MF solutions have been investigated: a correction factor-based MF solution and an extrapolation-based MF solution. However, the MF solution is a gray-box method, meaning it requires knowledge of the device under test (DUT). Furthermore, the accuracy of FF pattern reconstruction based on extrapolation solutions is limited due to design simplification.

[0003] Due to their compact size and high accuracy, near-field to far-field transformation-based solutions have been widely deployed in various applications. However, they require obtaining a large number of complex sample data on a closed sphere, resulting in long measurement times and the need for both phase and amplitude measurements. In applications where phase information is unavailable or inaccurate, complex signal measurement becomes difficult. This problem will become even more pronounced for future large-scale integrated antenna systems, as even more samples are required, and antenna ports may no longer be available due to highly integrated designs. Therefore, there is an urgent need for fast field conversion solutions based on phase-free measurements.

[0004] In many applications, a single-section frontal radiation pattern (FF) is sufficient to meet the measurement requirements of key parameters, such as the main lobe, side lobes, and nulls in a specific section. In such cases, near-field (NF) single-section solutions can reconstruct critical information of the device under test (DUT) using sampled data measured on a specific section, avoiding excessive measurements on closed surfaces. State-of-the-art methods primarily focus on two aspects: single-section algorithms based on complex measurements and algorithms based on amplitude-only measurements. Phase-free single-section methods based on dual-probe setups connect two probes to the same vector network analyzer, providing relative phase information between the probes. Meanwhile, pure amplitude single-section methods based on cylindrical wave expansion utilize two sampled sections, providing a fast pure amplitude method for antenna measurements. However, the determination of key system parameters, namely measurement distance, probe angle spacing, and probe angle range, has not been studied; these are critical factors for system cost and efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an antenna pattern reconstruction method that can achieve efficient phase-free far-field reconstruction by optimizing key parameters using only the energy information of the received signal.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An antenna pattern reconstruction method according to the present invention includes:

[0008] Two measurement distances are selected in the near field region, and the probe angle range and probe angle interval are determined. The amplitude data of the antenna is measured in a single-section direction to obtain the antenna near-field amplitude pattern in a single-section.

[0009] Copy the antenna near-field amplitude patterns measured at two distances along a single tangential direction to the azimuth angle in another spherical coordinate system. In terms of angle, obtain the near-field amplitude pattern of the 3D antenna on the two spherical surfaces;

[0010] Phase recovery is achieved by using the near-field amplitude patterns of 3D antennas on two spherical surfaces, thus obtaining the complex near-field patterns of the device under test on the two spherical surfaces.

[0011] The far-field radiation pattern of the antenna of the device under test is calculated based on the complex near-field radiation pattern of the device on the two spherical surfaces.

[0012] As a further optimization of the antenna pattern reconstruction method described in this invention, the far-field pattern of the antenna of the device under test is calculated by using the spherical near-field transformation algorithm of spherical wave expansion (SWE) based on the complex near-field pattern of the device under test on two spherical surfaces.

[0013] As a further optimization of the antenna pattern reconstruction method described in this invention, the single-section direction refers to the section direction in which the peak gain of the device under test is located. The single-section direction is... It is the azimuth angle in a spherical coordinate system.

[0014] As a further optimization of the antenna pattern reconstruction method described in this invention, the two measurement distances include a first measurement distance R1 and a second measurement distance R2, wherein the first measurement distance R1 is at least 0.15d. far There needs to be at least 0.2d between R1 and the second measurement distance R2. far The interval, i.e., R², is at least 0.35d. far , where d far This represents the far-field distance of the antenna.

[0015] As a further optimization of the antenna pattern reconstruction method described in this invention, the first measurement distance R1 is determined by a single-section near-far field conversion algorithm based on complex signal measurement, and the second measurement distance R2 is determined by a phase recovery algorithm.

[0016] As a further optimization of the antenna pattern reconstruction method described in this invention, the probe angle range is determined by the properties of the pattern of the device under test. For the device under test, if only the main beam and the first side lobe are needed, the probe angle range is 60° to 120°.

[0017] As a further optimization of the antenna pattern reconstruction method described in this invention, the probe angle interval should meet the following requirements: Where k is the wave number, r0 is the radius of the smallest sphere surrounding the device under test, and Δθ is the probe angle interval.

[0018] As a further optimization of the antenna pattern reconstruction method described in this invention, the antenna pattern reconstruction method is used to measure the radiation patterns of the device under test under different polarization modes.

[0019] As a further optimization of the antenna pattern reconstruction method described in this invention, if the power amplifier gain and probe gain in the measurement system link are known, the antenna pattern reconstruction method can be used to measure the gain of the device under test.

[0020] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0021] This invention presents an efficient and low-cost method for testing antenna patterns, and outlines the basic principles for selecting the sampling distance between two cross-sections, providing guidance for distance selection in antenna testing. Furthermore, it explains the principles for determining the probe angle range and probe angle spacing, which is helpful in designing cost-effective and efficient multi-probe anechoic chamber setups. Attached Figure Description

[0022] Figure 1 This is a diagram of the test apparatus for an embodiment of the present invention;

[0023] Figure 2 This is a flowchart of the direction map reconstruction process in an embodiment of the present invention;

[0024] Figure 3 This is a comparison diagram of the far-field radiation pattern obtained from different test ranges of the 12×8 array and the reference radiation pattern in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] This invention is an antenna pattern reconstruction method based on near-field single-section phase-free measurement:

[0027] First, determine the measurement settings, such as measurement distance, probe angle range, and probe angle interval, according to the measurement requirements. After determining the measurement settings, proceed in the single-plane direction. The amplitude data of the antenna is measured. Next, the near-field amplitude pattern of the antenna measured along a single sectional direction is copied to the azimuth angle in another spherical coordinate system. First, the near-field amplitude patterns of the 3D antenna on two spherical surfaces are obtained. Then, the phase recovery algorithm is used to perform phase recovery on the amplitude patterns on the two spherical surfaces to obtain the complex near-field patterns of the antenna under test on the two spherical surfaces. Finally, the far-field pattern of the antenna under test is calculated by the spherical near-field and far-field transformation algorithm of spherical wave expansion (SWE).

[0028] In one implementation case, the testing apparatus is as shown in the attached document. Figure 1 As shown, a basic transceiver station consisting of 12×8 units is used as the DUT. The spacing between adjacent units along the length and width is 6cm and 5cm, respectively. The overall dimensions of the DUT are 67cm×40cm, therefore the aperture of the DUT is 0.78m. The operating frequency of the DUT is 3.5GHz, corresponding to a wavelength of 85.7mm. The corresponding FF distance of the DUT is d. far =14.2m. Measurements were conducted in an anechoic chamber. The DUT was placed on a turntable, and a horn antenna was positioned at a certain distance from the DUT to measure NF amplitude data. NF data at different distances could be measured by moving the horn antenna along the normal direction of the DUT. The reference FF pattern of the DUT was measured directly in CATR.

[0029] To further illustrate the present invention, specific testing methods will be introduced below based on the above-described testing device example.

[0030] like Figure 2 As shown, the specific steps are as follows:

[0031] 1. Based on the proposed measurement setup determination method, two measurement distances R1 = 2m (0.15d) are selected in the near-field region. far ) and R2=5m(0.35d far The measurement probe angle interval Δθ = 5° (θ is the polar angle in spherical coordinates), and the measurement range is [30°, 150°], [45°, 135°], [60°, 120°], [75°, 105°]. The antenna angle in a single sectional direction is obtained through phase-free measurement. The amplitude data, the whole The NF data of the cross section can be obtained by rotating a turntable;

[0032] 2. Extend the single-plane amplitude data to the spherical near field by... The amplitude data at point is copied to all other points. The angle can be used to recover the NF pattern on the two spheres R1 and R2;

[0033] 3. The phase information on the two spheres is recovered using a phase retrieval algorithm, and then the complex NF pattern on the two spheres is recovered;

[0034] 4. Utilize spherical wave expansion to perform near-field and far-field transformations, and calculate the far-field radiation pattern;

[0035] from Figure 3 As can be seen, the main lobe can be accurately reconstructed using θ∈[75°,105°] and Δθ=5°. Specifically, only NF amplitude data from 7 positions on each slice are needed to reconstruct the main lobe pattern. Furthermore, the main lobe and the first side lobe can be accurately reconstructed using θ∈[60°,120°] and Δθ=5°. Specifically, NF amplitude data from 13 positions on each slice are needed to reconstruct the main lobe and the first side lobe.

[0036] A computer device includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to implement the steps of the antenna pattern reconstruction method described above.

[0037] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the antenna pattern reconstruction method described above.

[0038] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0039] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0040] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0041] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0042] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for reconstructing antenna radiation patterns, characterized in that, include: Two measurement distances are selected in the near field region, and the probe angle range and probe angle interval are determined. The amplitude data of the antenna is measured in a single-section direction to obtain the antenna near-field amplitude pattern in a single-section. Copy the antenna near-field amplitude patterns measured at two distances along a single tangential direction to the azimuth angle in another spherical coordinate system. In terms of angle, obtain the near-field amplitude pattern of the 3D antenna on the two spherical surfaces; Phase recovery is achieved by using the near-field amplitude patterns of 3D antennas on two spherical surfaces, thus obtaining the complex near-field patterns of the device under test on the two spherical surfaces. The far-field radiation pattern of the antenna of the device under test is calculated based on the complex near-field radiation pattern of the device on the two spherical surfaces.

2. The antenna pattern reconstruction method according to claim 1, characterized in that, Based on the complex near-field radiation patterns of the device under test on the two spherical surfaces, the far-field radiation pattern of the antenna of the device under test is calculated by the spherical near-field and far-field transformation algorithm of spherical wave expansion (SWE).

3. The antenna pattern reconstruction method according to claim 1, characterized in that, The single-section direction refers to the direction in which the peak gain of the device under test is located. It is the azimuth angle in spherical coordinates.

4. The antenna pattern reconstruction method according to claim 1, characterized in that, The two measurement distances include a first measurement distance R1 and a second measurement distance R2, where the first measurement distance R1 is at least 0.15d. far There needs to be at least 0.2d between R1 and the second measurement distance R2. far The interval, i.e., R², is at least 0.35d. far , where d far This represents the far-field distance of the antenna.

5. The antenna pattern reconstruction method according to claim 4, characterized in that, The first measurement distance R1 is determined by a single-section near-far field conversion algorithm based on complex signal measurement, and the second measurement distance R2 is determined by a phase recovery algorithm.

6. The antenna pattern reconstruction method according to claim 1, characterized in that, The probe angle range is determined by the properties of the radiation pattern of the device under test. For the device under test, if only the main beam and the first side lobe are needed, the probe angle range is 60° to 120°.

7. The antenna pattern reconstruction method according to claim 1, characterized in that, The probe angle interval should meet the following requirements. Where k is the wave number, r0 is the radius of the smallest sphere surrounding the device under test, and Δθ is the probe angle interval.

8. The antenna pattern reconstruction method according to claim 1, characterized in that, The antenna pattern reconstruction method is used to measure the radiation patterns of the device under test under different polarization modes.

9. The antenna pattern reconstruction method according to claim 1, characterized in that, If the power amplifier gain and probe gain in the measurement system link are known, the antenna pattern reconstruction method can be used to measure the gain of the device under test.

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