An antenna circular polarization mode testing device and method

Abstract

This invention relates to a device and method for testing the circular polarization of antennas, belonging to the field of antenna testing technology. The method includes a control console that rotates a first turntable at a constant speed. During the rotation of the first turntable, a vector network analyzer collects the amplitude and phase of the electromagnetic wave received by an auxiliary linearly polarized antenna from the circularly polarized antenna under test. The polarization direction of the circularly polarized antenna under test is determined based on the correspondence between the slope of the phase-time curve and the rotation direction of the first turntable. An anechoic chamber calibration is then performed. The received signal strength is measured as the maximum value, completing the alignment of the maximum radiation direction of the circularly polarized antenna under test. The first turntable is controlled to rotate at a constant speed, and the signal amplitude is collected by the vector network analyzer to form a sinusoidal amplitude-time envelope curve. The difference between the maximum and minimum values ​​of the envelope curve is extracted as the axial ratio of the circularly polarized antenna under test. Finally, the polarization direction of the circularly polarized antenna under test is determined. This method provides intuitive and accurate test results and is easy to implement for batch testing.

Description

Technical Field

[0001] This invention relates to the field of antenna testing technology, and more specifically, to an antenna circular polarization testing device and method. Background Technology

[0002] With the rapid development of modern wireless communication technology, the utilization of electromagnetic spectrum resources is becoming increasingly strained, and complex electromagnetic propagation poses a severe challenge to signal transmission quality. Among numerous antenna performance indicators, polarization is a key factor determining system communication capacity, anti-interference capability, and transmission efficiency. In engineering applications, compared to linear polarization, circularly polarized antennas have been widely used due to their unique performance advantages, mainly reflected in the orthogonality of circularly polarized waves, which can effectively resist Faraday rotation effects and multipath reflection interference. In scenarios such as satellite communication, radar detection, and mobile communication, after electromagnetic waves pass through the ionosphere or are reflected by complex environments, the polarization direction often undergoes unpredictable reversals. Linearly polarized antennas are prone to polarization mismatch, leading to severe signal fading, while circularly polarized waves can maintain a relatively stable state. However, the most critical and error-prone characteristic of circularly polarized antennas in application lies in their rotational characteristics, namely, the distinction between left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP). If the antenna rotation direction is incorrectly determined, it will lead to polarization mismatch between the transmitting and receiving ends, resulting in polarization isolation loss of up to tens of decibels. Therefore, accurate testing of the antenna's circular polarization performance, especially the accurate determination of the rotation direction and the precise measurement of the axial ratio, has become an indispensable and crucial step in the antenna research and development and production process.

[0003] In existing testing standards, the mainstream methods for determining the rotation direction of circular polarization are the "dual-channel receiving method" or the "multi-port polarized antenna method." These methods require the test system to have orthogonal dual-polarized receiving channels. A vector network analyzer simultaneously acquires horizontal and vertical components, followed by complex digital signal processing algorithms to calculate the phase difference, determining the rotation direction based on the sign of the phase difference. While this method offers acceptable accuracy, it requires expensive dual-polarized standard horns and dual-channel test systems, increasing maintenance difficulty and failure rate. In test environments lacking dual-channel calculation capabilities, engineers often use the "rotating linear polarized antenna method" to estimate the axial ratio. However, this method has an inherent physical flaw in determining rotation direction: when using a linear antenna as the standard antenna for rotation, the received signal amplitude envelope exhibits a sinusoidal change, and the amplitude-frequency response curves appear almost identical regardless of whether the antenna under test is left-hand or right-hand rotating. This means that simply rotating the linear polarized antenna and observing amplitude changes does not provide a visually intuitive distinction between left-hand and right-hand rotation. To address this issue, existing technologies often require manual intervention, involving comparative testing by manually replacing standard linearly polarized antennas with known rotation directions. This "comparative method" is not only cumbersome and time-consuming, but also difficult to implement closed-loop control on automated testing lines, severely hindering the improvement of testing efficiency.

[0004] Therefore, it is of practical significance to explore a simple testing device and method for rapidly determining the direction of circular polarization, so as to solve the shortcomings of the existing technology, such as the lack of intuitive physical determination means, cumbersome operation process and difficulty in adapting to automated testing production lines. Summary of the Invention

[0005] The purpose of this invention is to provide an antenna circular polarization testing device and method to improve the above-mentioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows: In a first aspect, this application provides an antenna circular polarization testing apparatus, comprising: Darkroom environment 7; The first turntable 1 and the second turntable 2 are both located within the darkroom environment 7; An auxiliary linearly polarized antenna 3 is mounted on the first turntable 1, with its central axis coinciding with the rotation center of the first turntable 1. The circularly polarized antenna 4 to be tested is mounted on the second turntable 2, with its central axis coinciding with the rotation center of the second turntable 2; The vector network analyzer 8 has its fifth port 5 connected to the auxiliary linearly polarized antenna 3 and its sixth port 6 connected to the circularly polarized antenna 4 under test. The control console is connected to the first turntable 1, the second turntable 2 and the vector network analyzer 8 respectively, and is used to control the rotation direction and speed of the first turntable 1; The control console controls the first turntable 1 to rotate at a constant speed. During the rotation of the first turntable 1, the vector network analyzer 8 collects the amplitude and phase of the electromagnetic wave 9 received by the auxiliary linear polarized antenna 3 from the circularly polarized antenna 4 under test. Based on the amplitude, the axial ratio of the circularly polarized antenna 4 under test is determined, and based on the correspondence between the slope of the phase-time curve and the rotation direction of the first turntable 1, the polarization direction of the circularly polarized antenna 4 under test is determined.

[0006] Preferably, the anechoic chamber environment 7 is a fully anechoic chamber, the interior walls of which are covered with carbon-based absorbing material, the absorption frequency covers the test frequency band, and its size meets the far-field conditions for antenna testing.

[0007] Preferably, the auxiliary linearly polarized antenna 3 is a standard linearly polarized horn antenna; the device also includes a standard linearly polarized antenna for anechoic chamber calibration before testing. When the standard linearly polarized antenna is installed, its central axis coincides with the rotation center of the second turntable 2. After calibration, it is replaced with the circularly polarized antenna 4 to be tested, and the relative spatial distance between the auxiliary linearly polarized antenna 3 and the transmitting antenna remains unchanged before and after the replacement.

[0008] Preferably, the rotation angular frequency of the first turntable 1 is less than the operating signal angular frequency of the circularly polarized antenna 4 under test, so that the vector network analyzer 8 can acquire complete signal amplitude and phase data within the scanning period; When the rotational angular frequency of the first turntable 1 is superimposed in the same direction as the operating signal angular frequency of the circularly polarized antenna 4 under test, the phase-time curve has a positive slope; when they are superimposed in opposite directions, the curve has a negative slope.

[0009] Secondly, this application also provides a method for testing the circular polarization of an antenna, including: S1: Install the standard linearly polarized antenna on the second turntable 2, adjust the first turntable 1 and the second turntable 2 so that the auxiliary linearly polarized antenna 3 is aligned with the maximum radiation direction of the standard linearly polarized antenna, fix the first turntable 1, and adjust the second turntable 2 until the transmission gain measured by the vector network analyzer 8 is at its maximum value, thus completing the anechoic chamber calibration. S2: Replace the standard linear polarized antenna with the circular polarized antenna 4 to be tested, keep the positions of the first turntable 1 and the auxiliary linear polarized antenna 3 unchanged, adjust the second turntable 2 until the received signal strength measured by the vector network analyzer 8 is at its maximum value, and complete the alignment of the maximum radiation direction of the circular polarized antenna 4 to be tested; S3: Keep the second turntable 2 fixed, control the first turntable 1 to rotate at a constant speed, collect the signal amplitude through the vector network analyzer 8, form a sinusoidal amplitude-time envelope curve, and extract the difference between the maximum and minimum values ​​of the envelope curve as the axial ratio of the circularly polarized antenna 4 under test. S4: During the rotation of the first turntable 1, the vector network analyzer 8 synchronously acquires the signal phase to form a phase-time curve. Based on the correspondence between the mechanical rotation direction of the first turntable 1 and the slope of the phase-time curve, the polarization direction of the circularly polarized antenna 4 under test is determined.

[0010] The beneficial effects of this invention are as follows: This invention provides a device and method for testing the circular polarization of antennas, relating to the field of antenna testing technology. The device includes a seventh anechoic chamber environment, two controllable first and second turntables, a third and a fourth antenna, and an eighth vector network (VRF) testing instrument. After calibration in the seventh anechoic chamber, the circularly polarized fourth antenna transmits a ninth electromagnetic wave on the second turntable, and the linearly polarized third antenna receives the ninth electromagnetic wave on the first turntable. The amplitude and phase characteristics of the received signal are measured using the eighth VRF. The device controls the first turntable to rotate at a constant speed, and combined with the high-precision measurement capability of the eighth VRF, it measures the amplitude characteristics by acquiring the maximum and minimum electric field amplitudes of the fourth antenna within the instrument's scanning period; the difference between these two values ​​represents the axial ratio of the fourth antenna. Regarding phase characteristics, it acquires the electric field phase of the fourth antenna within the instrument's scanning period. By comparing the relationship between the mechanical rotation direction of the third antenna following the first turntable and the phase curve of the fourth antenna, the polarization rotation direction of the fourth antenna can be determined. This device is simple to operate and low in cost; the method provides intuitive and accurate test results and is easy to implement for batch testing.

[0011] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the antenna circular polarization test method described in this embodiment of the invention; Figure 2This is a schematic diagram illustrating the principle of the antenna circular polarization testing method described in this embodiment of the invention; Figure 3 This is a schematic diagram of the test rotation direction of the antenna circular polarization method described in the embodiment of the present invention; Figure 4 This is a schematic diagram of the phase-time curve periodicity of the antenna circular polarization test method described in this embodiment of the invention.

[0014] In the diagram: 1. First turntable; 2. Second turntable; 3. Third antenna; 4. Fourth antenna; 5. Fifth port; 6. Sixth port; 7. Seventh anechoic chamber; 8. Eighth vector network; 9. Ninth electromagnetic wave. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0016] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. Example 1:

[0017] This embodiment provides a device for testing antenna circular polarization. See [link to documentation]. Figure 2 This includes: Darkroom environment 7; First turntable 1 and second turntable 2 are both located within the darkroom environment 7; An auxiliary linearly polarized antenna 3 is mounted on the first turntable 1, with its central axis coinciding with the rotation center of the first turntable 1; a circularly polarized antenna 4 to be tested is mounted on the second turntable 2, with its central axis coinciding with the rotation center of the second turntable 2. The vector network analyzer 8 has its fifth port 5 connected to the auxiliary linearly polarized antenna 3 and its sixth port 6 connected to the circularly polarized antenna 4 under test; the control console is connected to the first turntable 1, the second turntable 2 and the vector network analyzer 8 respectively, and is used to control the rotation direction and speed of the first turntable 1. The control console controls the first turntable 1 to rotate at a constant speed. During the rotation of the first turntable 1, the vector network analyzer 8 collects the amplitude and phase of the electromagnetic wave 9 received by the auxiliary linear polarized antenna 3 from the circularly polarized antenna 4 under test. Based on the amplitude, the axial ratio of the circularly polarized antenna 4 under test is determined, and based on the correspondence between the slope of the phase-time curve and the rotation direction of the first turntable 1, the polarization direction of the circularly polarized antenna 4 under test is determined.

[0018] Specifically, the anechoic chamber environment 7 is a fully anechoic chamber, whose interior walls are lined with carbon-based absorbing material, the absorption frequency of which covers the test frequency band, and its dimensions meet the far-field conditions for antenna testing as follows: In the formula, R is the minimum distance between the auxiliary linearly polarized antenna 3 and the circularly polarized antenna 4 under test, D is the maximum physical size of the aperture of the circularly polarized antenna 4 under test, and λ is the wavelength of the frequency corresponding to the working signal.

[0019] The auxiliary linearly polarized antenna 3 is a standard linearly polarized horn antenna; the device also includes a standard linearly polarized antenna for anechoic chamber calibration before testing. When the standard linearly polarized antenna is installed, its central axis coincides with the rotation center of the second turntable 2. After calibration, it is replaced with the circularly polarized antenna 4 to be tested, and the relative spatial distance between the auxiliary linearly polarized antenna 3 and the transmitting antenna remains unchanged before and after the replacement.

[0020] Specifically, a professional anechoic chamber 7 is selected for calibration. An auxiliary linearly polarized antenna 3 is installed on the first turntable 1, with its central axis coinciding with the rotation center of the first turntable 1. A standard linearly polarized antenna 4 is installed on the second turntable 2, with its central axis coinciding with the rotation center of the second turntable 2. A standard calibration kit is used to perform dual-port calibration on the vector network 8, with the calibration signal containing a specified bandwidth. After calibration, the fifth port 5 of the vector network 8 is connected to the auxiliary linearly polarized antenna 3, and the sixth port 6 is connected to the standard linearly polarized antenna 4. The control console is connected to the first turntable 1, the second turntable 2, and the vector network 8.

[0021] For antenna testing, replace the standard linearly polarized antenna 4 with the circularly polarized antenna 4 under test, with its central axis coinciding with the rotation center of the second turntable 2; keep the positions of the first turntable 1, auxiliary linearly polarized antenna 3, and vector network 8 unchanged; connect the first turntable 1, the second turntable 2, the vector network 8, and the circularly polarized antenna 4 under test to the control console.

[0022] Turntable 1, Turntable 2, Vector Grid 8, Auxiliary Linear Polarized Antenna 3, Standard Linear Polarized Antenna 4, and Circular Polarized Antenna 4 under Test are located inside anechoic chamber 7, while the control console is located outside anechoic chamber 7. Auxiliary Linear Polarized Antenna 3 and Standard Linear Polarized Antenna 4 are passive devices and do not require connection to the control console; Turntable 1, Turntable 2, and Vector Grid 8 are active devices and require connection to the control console; if the circular polarized antenna 4 under test is passive, it does not require connection to the control console; if it is active, it requires connection to the control console.

[0023] The auxiliary linearly polarized antenna 3 and the standard linearly polarized antenna 4 are selected as horn-line polarized antennas. The circularly polarized antenna 4 under test can be either a passive circularly polarized antenna or an active circularly polarized antenna.

[0024] Vector network 8 connects to each antenna via low-loss coaxial cable, and Vector network 8 connects to the control console via network cable; the control console connects to each turntable and the antenna under test via control line; Anechoic chamber 7 is equipped with an electromagnetic shielding door, ventilation system, and power supply system; the interior walls of anechoic chamber 7 are lined with carbon-based or other absorbing materials, absorbing frequencies covering the test frequency band to ensure no external electromagnetic interference; the dimensions of anechoic chamber 7 need to meet the far-field conditions for antenna testing. Example 2:

[0025] like Figure 1 As shown, this embodiment provides a method for testing the circular polarization of an antenna. See [link to documentation]. Figure 1 The method includes: S1: Install the standard linearly polarized antenna on the second turntable 2, adjust the first turntable 1 and the second turntable 2 so that the auxiliary linearly polarized antenna 3 is aligned with the maximum radiation direction of the standard linearly polarized antenna, fix the first turntable 1, and adjust the second turntable 2 until the transmission gain measured by the vector network analyzer 8 is at its maximum value, thus completing the anechoic chamber calibration. S2: Replace the standard linear polarized antenna with the circular polarized antenna 4 to be tested, keep the positions of the first turntable 1 and the auxiliary linear polarized antenna 3 unchanged, adjust the second turntable 2 until the received signal strength measured by the vector network analyzer 8 is at its maximum value, and complete the alignment of the maximum radiation direction of the circular polarized antenna 4 to be tested; S3: Keep the second turntable 2 fixed, control the first turntable 1 to rotate at a constant speed, collect the signal amplitude through the vector network analyzer 8, form a sinusoidal amplitude-time envelope curve, and extract the difference between the maximum and minimum values ​​of the envelope curve as the axial ratio of the circularly polarized antenna 4 under test. S4: During the rotation of the first turntable 1, the vector network analyzer 8 synchronously acquires the signal phase to form a phase-time curve. Based on the correspondence between the mechanical rotation direction of the first turntable 1 and the slope of the phase-time curve, the polarization direction of the circularly polarized antenna 4 under test is determined.

[0026] Specifically, when looking from the circularly polarized antenna 4 under test to the auxiliary linearly polarized antenna 3, if the first turntable 1 rotates clockwise and the slope of the phase-time curve is positive, or the first turntable 1 rotates counterclockwise and the slope of the phase-time curve is negative, then the circularly polarized antenna 4 under test is determined to be left-hand circularly polarized; if the first turntable 1 rotates clockwise and the slope of the phase-time curve is negative, or the first turntable 1 rotates counterclockwise and the slope of the phase-time curve is positive, then the circularly polarized antenna 4 under test is determined to be right-hand circularly polarized.

[0027] Specifically, in step S2, when the received signal strength measured by the vector network analyzer 8 is unstable or spikes appear on the amplitude curve, the transmit power of the sixth port 6 of the vector network analyzer 8 is increased until the received signal strength is stable.

[0028] Specifically, in step S3, the axial ratio test utilizes the amplitude characteristics of the working signal to periodically collect the major and minor axes of the elliptical trajectory of the circularly polarized electromagnetic wave through the mechanical rotation of the auxiliary linearly polarized antenna 3; in step S4, the rotation direction test utilizes the phase characteristics of the working signal to determine the direction of rotation through the physical relationship between the mechanical rotation direction and the electric field phase change direction; the axial ratio test and the rotation direction test are completed based on the same set of testing equipment and the same rotation action.

[0029] Specifically, in steps S3 and S4, the rotation speed of the first turntable 1 is controlled by the control console according to the scanning cycle of the vector network analyzer 8, ensuring that complete amplitude-time envelope curve and phase-time curve data are acquired within a single scanning cycle, thereby achieving semi-automated batch testing.

[0030] It should be noted that in this embodiment, S1. assumes the lowest frequency of the operating signal of the circularly polarized fourth antenna under test. Center frequency highest frequency The operating signal frequency coverage of the auxiliary linearly polarized third antenna and the standard linearly polarized fourth antenna. arrive According to the fundamental formula of wave physics: in, It is wave speed; It is the wavelength corresponding to the frequency of the working signal; It refers to frequency.

[0031] Far-field formula for antenna testing: in, It is the minimum distance between the auxiliary linearly polarized third antenna and the circularly polarized fourth antenna under test; This is the maximum physical size of the aperture of the circularly polarized fourth antenna under test. For aperture surface antennas, it refers to its diameter or maximum side length; for array antennas, it refers to the maximum size of the array. The dimensions of the seventh anechoic chamber meet the minimum far-field distance requirement for antenna testing. The test results are all based on far-field conditions.

[0032] The eighth vector network is set to continuous wave mode, with frequency coverage... arrive Amplitude mode test: Turn on the eighth vector network transmitter switch and observe: in, It is the gain from port 6 to port 5; It is the transmit power of port 6; This is the loss of the coaxial cable from the sixth port to the standard line polarized fourth antenna, taken as a positive value; It is the gain of the standard linearly polarized fourth antenna; It satisfies the far-field distance The ninth electromagnetic wave attenuates in the seventh anechoic chamber, taking a positive value; It is the gain of the auxiliary linearly polarized third antenna; dissipation This is the coaxial cable loss from the auxiliary polarization third antenna to the fifth port, taken as a positive value.

[0033] S2. Precisely adjust the first turntable via the control panel so that the central axis of the main lobe of the auxiliary linearly polarized third antenna mounted on the first turntable is aligned with the central axis of the standard circularly polarized fourth antenna mounted on the second turntable, ensuring optimal signal transmission path. Fix the position of the first turntable; then adjust the second turntable and observe. Amplitude value, in dB, when When the amplitude reaches its maximum, fix the second turntable, thus completing the calibration of the seventh darkroom.

[0034] Because the auxiliary linearly polarized third antenna is mechanically mounted on the first turntable and the standard circularly polarized fourth antenna is mechanically mounted on the second turntable, the fixed positions of the first and second turntables are equivalent to the fixed positions of the auxiliary linearly polarized third antenna and the standard circularly polarized fourth antenna, meaning the spatial distance between the two antennas is fixed. Sure.

[0035] S3. Remove the standard linearly polarized fourth antenna from the second turntable. Install the circularly polarized fourth antenna to be tested in the same position on the second turntable, ensuring that the central axis of the circularly polarized fourth antenna coincides with the rotation center of the second turntable. After installation, adjust the second turntable via the control panel so that the position of the circularly polarized fourth antenna to be tested is the same as that of the standard linearly polarized fourth antenna, ensuring the relative spatial distance between the circularly polarized fourth antenna to be tested and the auxiliary linearly polarized third antenna. Unchanged, i.e., the attenuation of the ninth electromagnetic wave constant.

[0036] Keep Under constant conditions, during the rotation of the second turntable, the signal strength received at the fifth port of the eighth vector network is monitored in real time. Observe the changes in radiation intensity of the fourth circularly polarized antenna under test at different angles. When the signal amplitude is detected... When the maximum radiation is reached, record the angular position of the second turntable, which is the maximum radiation direction of the circularly polarized fourth antenna under test. Define this position as the normal of the circularly polarized fourth antenna under test, and normalize it to zero degrees. Note that monitoring... If the amplitude is unstable or spikes appear on the amplitude curve, the transmit power of the sixth port of the eighth vector network should be increased appropriately. ,until Only when the amplitude is stable can the test results be reliable.

[0037] S4. Keeping the second turntable stationary, start the first turntable via the control console to control the rotation speed of the auxiliary linearly polarized third antenna, so that the eighth vector network can acquire the signal within the scanning period; during the rotation of the auxiliary linearly polarized third antenna, the eighth vector network can periodically acquire the major and minor axes of the signal's elliptic polarization, a phenomenon characterized by the formation of [something] in the time domain. The sinusoidal amplitude-time envelope curve; the difference between the maximum and minimum values ​​of the envelope curve amplitude reflects the difference between the major and minor axes, which is the axial ratio of the antenna.

[0038] In other words, the fourth circularly polarized antenna under test is theoretically circularly polarized, but in reality it is elliptically polarized. The axial ratio measures the degree of degradation from circular polarization to elliptical polarization; the axial ratio test utilizes the amplitude characteristics of the working signal.

[0039] Without loss of generality, assume that when looking from the radiating aperture of the circularly polarized fourth antenna to the auxiliary linearly polarized third antenna, the auxiliary linearly polarized third antenna is rotated clockwise with a rotation angular frequency of . The mechanical rotation forms circle 1; because the auxiliary linearly polarized third antenna coincides with the center line of the first turntable, the linear polarization trajectory of the auxiliary linearly polarized third antenna will pass through the center of circle 1, forming an electric field trajectory projection. .

[0040] Assume the fourth circularly polarized antenna under test transmits a left-hand circularly polarized ninth electromagnetic wave, with an operating signal angular frequency of... The electric field polarization trajectory is projected as circle 2; since the circularly polarized ninth electromagnetic wave can be decomposed into the superposition of two orthogonal, equally amplitude linearly polarized ninth electromagnetic waves, the electric field... Decomposed into two orthogonal parts and , while the axial ratio indicates and The actual amplitudes may not be equal; this process is as follows: Figure 3 As shown.

[0041] Assume the initial phase of the fourth circularly polarized antenna under test is Then at time The auxiliary line-polarized third antenna received the signal from the circularly polarized fourth antenna under test, because and vertical, and Therefore, the eighth vector network will only collect data that is parallel to the target vector. and Signal superposition; without loss of generality, the rotation direction of the auxiliary line-polarized third antenna is defined as the positive direction, i.e. If it is a positive value, then Absolute value can be taken Indicates and The magnitude in the relative direction, therefore the phase acquired by the eighth vector network. This can be expressed as: in, It is the phase acquired by the eighth vector network; It is the rotation angular frequency of the auxiliary line-polarized third antenna; It is the absolute value of the angular frequency of the operating signal of the fourth circularly polarized antenna under test; This refers to a specific moment during the data collection of the eighth vector network in the test; It is the initial phase of the fourth circularly polarized antenna under test.

[0042] based on Figure 3 have to ,but This indicates that the phase-time curve has a positive slope; furthermore, because the working signal is periodic, the phase-time curve is also periodic, as shown below. Figure 4 As shown.

[0043] If the auxiliary line polarization third antenna is rotated counterclockwise, we get Because the frequency of mechanical rotation is much lower than the operating frequency of the signal, that is ,but At this point, the phase-time curve has a negative slope and is also periodic.

[0044] Therefore, when looking from the fourth circularly polarized antenna under test towards the third auxiliary linearly polarized antenna, the rotation direction of the fourth circularly polarized antenna under test can be determined by referring to Table 1.

[0045] Table 1 Note that both the axial ratio test and the rotation test rely on the rotation of the first turntable. However, the axial ratio test does not consider the rotation direction of the first turntable, while the rotation test utilizes the relationship between the rotation direction of the first turntable and the antenna polarization direction. By measuring the amplitude and phase characteristics of the electric field under the same device, the test of the antenna's circular polarization mode is completed.

[0046] In summary, the testing device for antenna circular polarization provided by this invention utilizes a mechanical turntable to collect the ninth electromagnetic wave and tests the polarization mode through the relationship between mechanical rotation and polarization direction. The testing device has a simple operation process and can complete semi-automated batch testing tasks. The testing method for antenna circular polarization provided by this invention utilizes the amplitude and phase characteristics of the propagation of the circularly polarized ninth electromagnetic wave to achieve an intuitive physical determination method. The test results do not require secondary data processing and analysis, which is beneficial to improving the efficiency of engineering testing.

[0047] It should be noted that the specific methods by which each module performs operations in the system described in the above embodiments have been described in detail in the embodiments related to the method, and will not be elaborated here.

Claims

1. A device for testing the circular polarization of an antenna, characterized in that, include: Darkroom environment (7); The first turntable (1) and the second turntable (2) are both located within the darkroom environment (7); An auxiliary linearly polarized antenna (3) is mounted on the first turntable (1), and its central axis coincides with the rotation center of the first turntable (1). The circularly polarized antenna (4) to be tested is mounted on the second turntable (2), and its central axis coincides with the rotation center of the second turntable (2); The vector network analyzer (8) has its fifth port (5) connected to the auxiliary linear polarized antenna (3) and its sixth port (6) connected to the circularly polarized antenna (4) under test. The control console is connected to the first turntable (1), the second turntable (2) and the vector network analyzer (8) respectively, and is used to control the rotation direction and speed of the first turntable (1); The control console controls the first turntable (1) to rotate at a constant speed. During the rotation of the first turntable (1), the vector network analyzer (8) collects the amplitude and phase of the electromagnetic wave (9) received by the auxiliary linear polarized antenna (3) from the circularly polarized antenna (4) under test. The axial ratio of the circularly polarized antenna (4) under test is determined according to the amplitude, and the polarization direction of the circularly polarized antenna (4) under test is determined according to the correspondence between the slope of the phase-time curve and the rotation direction of the first turntable (1).

2. The antenna circular polarization testing device according to claim 1, characterized in that, The anechoic chamber environment (7) is a fully anechoic chamber, with its interior walls covered by carbon-based absorbing material. The absorption frequency covers the test frequency band, and its dimensions meet the far-field conditions for antenna testing as follows: In the formula, R is the minimum distance between the auxiliary linearly polarized antenna (3) and the circularly polarized antenna (4) under test, D is the maximum physical size of the aperture of the circularly polarized antenna (4) under test, and λ is the wavelength of the frequency corresponding to the working signal.

3. The antenna circular polarization testing device according to claim 1, characterized in that, The auxiliary linearly polarized antenna (3) is a standard linearly polarized horn antenna; the device also includes a standard linearly polarized antenna for anechoic chamber calibration before testing. When the standard linearly polarized antenna is installed, its central axis coincides with the rotation center of the second turntable (2). After calibration, it is replaced with the circularly polarized antenna (4) to be tested, and the relative spatial distance between the auxiliary linearly polarized antenna (3) and the transmitting antenna remains unchanged before and after the replacement.

4. The antenna circular polarization testing device according to claim 1, characterized in that, The rotation angular frequency of the first turntable (1) is less than the operating signal angular frequency of the circularly polarized antenna (4) under test, so that the vector network analyzer (8) can acquire complete signal amplitude and phase data within the scanning period. The calculation formula of the phase-time curve is as follows: In the formula, Let t represent the acquired phase, and t be the acquisition time. The initial phase of the circularly polarized antenna (4) under test is given by [missing information]. The rotation angular frequency of the auxiliary linearly polarized third antenna. The absolute value of the angular frequency of the operating signal of the fourth circularly polarized antenna under test; When the rotation angular frequency of the first turntable (1) is superimposed in the same direction as the working signal angular frequency of the circularly polarized antenna (4) under test, the phase-time curve has a positive slope, and when they are superimposed in opposite directions, the curve has a negative slope.

5. A method for testing the circular polarization of an antenna, using the antenna circular polarization testing apparatus according to any one of claims 1-4, characterized in that, include: S1: Install the standard linear polarized antenna on the second turntable (2), adjust the first turntable (1) and the second turntable (2) so that the auxiliary linear polarized antenna (3) is aligned with the maximum radiation direction of the standard linear polarized antenna, fix the first turntable (1), and adjust the second turntable (2) until the transmission gain measured by the vector network analyzer (8) is the maximum value, and complete the anechoic chamber calibration; S2: Replace the standard linear polarized antenna with the circular polarized antenna to be tested (4), keep the positions of the first turntable (1) and the auxiliary linear polarized antenna (3) unchanged, adjust the second turntable (2) until the received signal strength measured by the vector network analyzer (8) is the maximum value, and complete the alignment of the maximum radiation direction of the circular polarized antenna to be tested (4); S3: Keep the second turntable (2) fixed, control the first turntable (1) to rotate at a constant speed, collect the signal amplitude through the vector network analyzer (8), form a sinusoidal amplitude-time envelope curve, and extract the difference between the maximum and minimum values ​​of the envelope curve as the axial ratio of the circularly polarized antenna (4) under test; S4: During the rotation of the first turntable (1), the vector network analyzer (8) synchronously collects the signal phase and forms a phase-time curve. Based on the correspondence between the mechanical rotation direction of the first turntable (1) and the slope of the phase-time curve, the polarization direction of the circularly polarized antenna (4) under test is determined.

6. The antenna circular polarization testing method according to claim 5, characterized in that, The rule for determining the polarization direction in step S4 is as follows: When looking from the circularly polarized antenna (4) under test to the auxiliary linearly polarized antenna (3), if the first turntable (1) rotates clockwise and the slope of the phase-time curve is positive, or the first turntable (1) rotates counterclockwise and the slope of the phase-time curve is negative, then the circularly polarized antenna (4) under test is determined to be left-hand circularly polarized. If the first turntable (1) rotates clockwise and the slope of the phase-time curve is negative, or if the first turntable (1) rotates counterclockwise and the slope of the phase-time curve is positive, then the circularly polarized antenna (4) under test is determined to be right-hand circularly polarized.

7. The antenna circular polarization testing method according to claim 5, characterized in that, In step S2, when the received signal strength measured by the vector network analyzer (8) is unstable or spikes appear on the amplitude curve, the transmit power of the sixth port (6) of the vector network analyzer (8) is increased until the received signal strength is stable.

8. The method for testing the circular polarization of an antenna according to claim 5, characterized in that, In step S3, the axial ratio test utilizes the amplitude characteristics of the working signal to periodically collect the major and minor axes of the elliptical trajectory of the circularly polarized electromagnetic wave through the mechanical rotation of the auxiliary linearly polarized antenna (3); in step S4, the rotation direction test utilizes the phase characteristics of the working signal to determine the direction of rotation through the physical relationship between the mechanical rotation direction and the electric field phase change direction; the axial ratio test and the rotation direction test are completed based on the same set of testing equipment and the same rotation action.

9. The method for testing the circular polarization of an antenna according to claim 5, characterized in that, In step S1, the transmission gain satisfies the following formula: Wherein, S12 is the transmit power of the sixth port (6), L2 is the coaxial cable loss from the sixth port (6) to the transmitting antenna, G2 is the transmit antenna gain, L is the spatial attenuation of electromagnetic waves (9) in the anechoic chamber environment (7), G1 is the gain of the auxiliary linearly polarized antenna (3), and L1 is the coaxial cable loss from the auxiliary linearly polarized antenna (3) to the fifth port (5).

10. The method for testing the circular polarization of an antenna according to claim 5, characterized in that, In steps S3 and S4, the rotation speed of the first turntable (1) is controlled by the control console according to the scanning cycle of the vector network analyzer (8) to ensure that complete amplitude-time envelope curve and phase-time curve data are collected within a single scanning cycle, thereby achieving semi-automatic batch testing.

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