Chip antenna phase center alignment method

Abstract

The invention discloses a chip antenna phase center alignment method, and belongs to the technical field of chip antennae, and the method comprises the steps: carrying out the pre-scanning of a phase pattern of a chip antenna through a scanning frame, carrying out the judgment of the position deviation of a phase center and an actual scanning center through the obtained phase pattern data, and adjusting the position of a scanning circle center, before testing, the position of the phase center of the antenna is determined through simulation, and a coordinate system is established by referring to the phase center obtained through simulation during testing. According to the center alignment method, the position of an actual phase center is confirmed by carrying out a phase pattern pre-scanning technology, so that the accuracy of data, such as a far-field pattern and spherical near-field amplitude phase data, obtained through spherical scanning is ensured; the problem that the phase center of the chip antenna cannot be confirmed through a simple geometric position is solved, and compared with an existing testing process, the problem that the phase center of the chip antenna is difficult to calibrate due to factors such as the structure and the size of the chip antenna is solved.

Description

Technical Field

[0001] This invention belongs to the field of chip antenna technology, and particularly relates to a method for aligning the phase center of a chip antenna. Background Technology

[0002] Chip antennas are fabricated on a wafer using CMOS technology, integrating the antenna with the integrated circuit within the wafer. Compared to traditional planar antennas, this reduces signal transmission links, resulting in advantages such as low high-frequency loss, high integration, and small size. They are widely used in array radar, satellite communication, and remote sensing. Typically, they utilize the atmospheric absorption peak of wireless signals around 60GHz to ensure the safety and anti-interference capabilities of chip antennas for short-range electromagnetic communication signal transmission. Existing technology includes a two-dimensional phased array chip antenna for satellite communication, which integrates 4096 nanometer antennas onto a silicon substrate, with a size equivalent to only a pinhead.

[0003] Chip antennas, due to their structure differing from antennas with common feeding methods, typically have an extremely small area. Furthermore, for microstrip antennas, which are commonly used on-chip antennas, the phase center is difficult to determine through simple geometric center calibration. Even if the phase center position is obtained through simulation, it can be offset by factors such as manufacturing precision, differences in substrate dielectric constant, and thickness. Moreover, given their extremely small area, for a 300GHz wavelength, calibrating the phase center requires at least one-twentieth of a wavelength, or an accuracy of 0.05mm or higher, to essentially guarantee the accuracy of phase testing.

[0004] Therefore, it is extremely difficult to accurately calibrate the phase center of the chip antenna using instruments and equipment before testing. Even the phase center deviation at different frequencies can vary greatly. Therefore, before actual testing, it is necessary to determine the position of the antenna phase center through simulation. During actual testing, the coordinate system is established by referring to the phase center obtained from the simulation.

[0005] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a chip antenna phase center alignment method. By performing phase pattern pre-scanning technology, the actual phase center position is confirmed, thereby ensuring the accuracy of data that needs to be obtained through spherical scanning, such as far-field patterns and spherical near-field amplitude and phase data. This solves the problem that the phase center of a chip antenna cannot be confirmed through simple geometric positioning.

[0007] To achieve the above objectives, this invention proposes a chip antenna phase center alignment method, the center alignment method comprising:

[0008] The phase pattern of the chip antenna is pre-scanned using a scanning frame. The obtained phase pattern data is used to determine the positional offset between the phase center and the actual scanning center, thereby adjusting the position of the scanning center.

[0009] When the antenna of the chip under test meets the far-field condition, any complex antenna of any size can be replaced by a simple point source at a sufficiently far observation position.

[0010] Preferably, under the condition of meeting the engineering application, the definition of the phase center is partially weakened, and an approximate phase center that meets the requirements of the engineering application is found. If there is a point that makes the phase distribution of the antenna main lobe the flattest, then the point is defined as the "apparent phase center" of the antenna.

[0011] Preferably, the apparent phase center differs in the following two aspects in its definition:

[0012] "Main lobe" focuses on phase information within the main lobe without considering phase information across the entire space.

[0013] "The phase distribution is the flattest" means that, under the premise of meeting the application requirements, the phase distribution is allowed to have small fluctuations, and the maximum and minimum difference of the phase is constrained to be within a certain range or its change is minimized.

[0014] Preferably, before testing the antenna to be calibrated, the rotation center of the robotic arm is ensured to coincide with the phase center of the antenna. The robotic arm pre-scanning technology is used to determine whether the scanning center of the robotic arm coincides with the phase center by judging the phase-angle curve during the pre-scan.

[0015] Preferably, the robotic arm pre-scanning technology operates as follows:

[0016] Select the antenna test surface, position the robotic arm scanning center to the phase center of the antenna of the chip under test, take the antenna aperture direction as 0 degrees, control the robotic arm to scan the antenna test surface at an angle of -20° to 20°, read the phase information at this time, and draw its far-field phase pattern.

[0017] Preferably, the far-field phase pattern reflects the following:

[0018] The phase lags sequentially within the scanning range, requiring the receiving antenna to be moved to the left. After moving to the left, the position is adjusted by measurement until a flat phase pattern is obtained.

[0019] The phases lead sequentially within the scanning range, requiring the receiving antenna to be moved to the right.

[0020] The phase lags and then leads within the scanning range, and the phase is consistent at symmetrical points, so the receiving antenna needs to be moved closer to the chip antenna.

[0021] The phase leads and then lags within the scanning range, and the phase is consistent at symmetrical points, so the receiving antenna needs to be moved away from the chip antenna.

[0022] Since the center and phase center are offset to the left, right, up, and down, the phase curve obtained by scanning needs to be fitted once to separate the first component of the curve as the left and right offset of the scanning center and phase center. Then, by analyzing the trend of subtracting the first fitted line, the up and down offset of the scanning center and phase center can be obtained. At this point, the alignment of the robotic arm scanning center with the chip antenna phase center is completed.

[0023] The chip antenna phase center alignment method proposed in this invention can bring the following beneficial effects:

[0024] 1. The center alignment method of the present invention confirms the position of the actual phase center by performing phase pattern pre-scanning technology, thereby ensuring the accuracy of data that needs to be obtained through spherical scanning, such as far-field radiation patterns and spherical near-field amplitude and phase data, and solving the problem that the phase center of the chip antenna cannot be confirmed by simple geometric position.

[0025] 2. Compared with existing testing procedures, the alignment method of this invention solves the problem of phase center calibration difficulties caused by the structure and size of chip antennas, and provides data accuracy assurance for subsequent spherical related testing and calibration procedures. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a schematic diagram of the phase pattern measurement process according to the present invention;

[0028] Figure 2 This is a schematic diagram of the combined superposition of phase-angle curves according to the present invention. Detailed Implementation

[0029] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.

[0030] A method for aligning the phase center of a chip antenna involves using a scanning frame to pre-scan the phase pattern of the chip antenna, judging the positional offset between the phase center and the actual scanning center based on the obtained phase pattern data, and adjusting the position of the scanning center to achieve the final alignment with the phase center.

[0031] Because the structure of chip antennas differs from that of antennas with common feeding methods, the phase center of the chip antenna is far from the empirical position of the antenna phase center, and the phase center deviation can be large at different frequencies. Therefore, before actual testing, it is necessary to determine the position of the antenna phase center through simulation. During actual testing, the coordinate system is established with reference to the phase center obtained from the simulation.

[0032] Except for point sources, the phase of the far-field radiation sphere of an antenna is not constant, and any antenna is astigmatic within a finite range, which is related to the distance from the field point to the source point and the aperture field distribution. However, when the antenna of the chip under test meets the far-field condition, the tiny phase changes that exist near the actual antenna can be ignored, and any complex antenna of any size can be replaced by a simple point source at a sufficiently distant observation position.

[0033] Under the condition of meeting engineering application requirements, the definition of the phase center is partially weakened to find an approximate phase center that meets the requirements of engineering applications. If there exists a point that makes the phase distribution of the antenna main lobe the flattest, then this point is defined as the antenna's "apparent phase center" (apparent phase center). Compared with the strict definition of the phase center, the apparent phase center differs in two aspects in its definition:

[0034] First, the "main lobe": The vast majority of the antenna's energy is concentrated in the antenna's main lobe, and the main lobe is also the primary component used in engineering. Therefore, the focus is on the phase information within the main lobe, rather than considering the phase information across the entire space.

[0035] Second, "the flattest phase distribution" means that the phase of the far-field radiating sphere is constant. However, antennas other than point sources cannot meet this condition. Therefore, under the premise of meeting the application requirements, the phase distribution is allowed to have small fluctuations. The maximum and minimum phase difference can be constrained to be within a certain range or its change is minimized.

[0036] Before testing the antenna under calibration, it is essential to ensure that the rotation center of the robotic arm coincides with the phase center of the antenna. This is crucial for guaranteeing the accuracy of the chip antenna pattern during calibration. For the highest frequency point of 110GHz in the project, a deviation of 1mm can result in a phase shift of 132 degrees, affecting the accuracy of the pattern. Simply relying on the precise fixation of the robotic arm is insufficient to determine whether the scanning center point coincides with the phase center of the chip antenna, and the phase center position obtained from the initial simulation will inevitably differ from the actual phase center of the fabricated antenna. Therefore, the project proposes using robotic arm pre-scanning technology to determine whether the robotic arm's scanning center coincides with the phase center by analyzing the phase-angle curve during pre-scanning.

[0037] The specific operation of the robotic arm pre-scanning technology is as follows:

[0038] Select the antenna surface to be tested, and position the robotic arm scanning center to the phase center of the antenna of the chip under test (preliminary positioning). Set the antenna aperture direction to 0 degrees, and control the robotic arm to scan the antenna surface to be tested at an angle of -20° to 20°. Read the phase information at this time and plot its far-field phase pattern, as shown below. Figure 1 As shown, the following situations may occur:

[0039] The phase lags sequentially within the scanning range, such as... Figure 1 As shown in a, this indicates that the phase center of the chip antenna has no longitudinal offset, only a lateral offset. Based on this, it can be determined that the phase center of the chip antenna is offset to the right (standing behind the feed). The receiving antenna needs to be moved to the left. After moving to the left, continue to measure and adjust the position until a flat phase diagram is obtained.

[0040] The phases lead sequentially within the scanning range, such as... Figure 1 As shown in b, the phase center position is off to the left (standing behind the feed), and the receiving antenna needs to be moved to the right.

[0041] The phase initially lags and then leads within the scanning range, and the phases at symmetrical points are basically consistent, such as... Figure 1 As shown in c, this indicates that there is only a longitudinal phase shift and no lateral phase shift, so the receiving antenna needs to be moved closer to the chip antenna.

[0042] The phase initially leads and then lags within the scanning range, and the phases at symmetrical points are basically consistent, such as... Figure 1 As shown in d, this indicates that there is only a vertical phase shift and no horizontal phase shift, so the receiving antenna needs to be moved away from the chip antenna.

[0043] In addition, there may be situations where the scan center and phase center are offset to the left, right, up, and down. In this case, the phase-angle curve will appear as follows: Figure 2 In cases of combined superposition, the phase curve obtained from the scan needs to be fitted first to separate the primary component of the curve as the left-right offset between the scan center and the phase center. Then, by analyzing the trend of subtracting the primary fitted line, the vertical offset between the scan center and the phase center can be obtained. This completes the alignment of the robotic arm's scan center with the chip antenna's phase center.

[0044] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for aligning the phase center of a chip antenna, characterized in that, Center alignment methods include: The phase pattern of the chip antenna is pre-scanned using a scanning frame. The obtained phase pattern data is used to determine the positional offset between the phase center and the actual scanning center, thereby adjusting the position of the scanning center. When the antenna of the chip under test meets the far-field condition, any complex antenna of any size can be replaced by a simple point source at a sufficiently far observation position.

2. The chip antenna phase center alignment method according to claim 1, characterized in that, Under the condition of meeting engineering application requirements, the definition of phase center is partially weakened to find an approximate phase center that meets the requirements of engineering application. If there exists a point that makes the phase distribution of the antenna main lobe the flattest, then this point is defined as the "apparent phase center" of the antenna.

3. The chip antenna phase center alignment method according to claim 2, characterized in that, The apparent phase center differs in the following two aspects in its definition: "Main lobe" focuses on phase information within the main lobe without considering phase information across the entire space. "Flattest phase distribution" means that, while meeting application requirements, the phase distribution is allowed to have small fluctuations, and the difference between the maximum and minimum phase values ​​is constrained to be within a certain range or its variation is minimized.

4. The chip antenna phase center alignment method according to claim 3, characterized in that, Before testing the antenna under test, ensure that the rotation center of the robotic arm coincides with the phase center of the antenna. Using the robotic arm pre-scanning technology, determine whether the scanning center of the robotic arm coincides with the phase center by judging the phase-angle curve during the pre-scan.

5. The chip antenna phase center alignment method according to claim 4, characterized in that, The specific operation of the robotic arm pre-scanning technology is as follows: Select the antenna test surface, position the robotic arm scanning center to the phase center of the antenna of the chip under test, take the antenna aperture direction as 0 degrees, control the robotic arm to scan the antenna test surface at an angle of -20° to 20°, read the phase information at this time, and draw its far-field phase pattern.

6. The chip antenna phase center alignment method according to claim 5, characterized in that, The far-field phase pattern reflects the following: The phase lags sequentially within the scanning range, so the receiving antenna needs to be moved to the left. After moving to the left, the position needs to be measured and adjusted until a flat phase pattern is obtained. The phases lead sequentially within the scanning range, requiring the receiving antenna to be moved to the right; The phase lags and then leads within the scanning range, and the phase is consistent at symmetrical points, so the receiving antenna needs to be moved closer to the chip antenna. The phase leads and then lags within the scanning range, and the phase is consistent at symmetrical points, so the receiving antenna needs to be moved away from the chip antenna. Since the center and phase center are offset to the left, right, up, and down, the phase curve obtained by scanning needs to be fitted once to separate the first component of the curve as the left and right offset of the scanning center and phase center. Then, by analyzing the trend of subtracting the first fitted line, the up and down offset of the scanning center and phase center can be obtained. At this point, the alignment of the robotic arm scanning center with the chip antenna phase center is completed.

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