A near-field test system and method for circularly polarized antenna parameters

Abstract

The present invention relates to a near-field testing system and method for circularly polarized antenna parameters. Existing circularly polarized antenna testing technology cannot meet practical requirements. Therefore, based on novel electromagnetic quantum detection technology, the present invention utilizes the coupling relationship between electromagnetic waves and Rydberg atoms, as well as the relationship between the atomic energy level wave function in the Rydberg state and the response state of electromagnetic waves. By cleverly designing a laser path and utilizing the interaction between lasers and alkali metal atoms, and using a heterodyne method related to Rydberg atom-based electromagnetic wave phase measurement, the system innovatively solves the problem of real-time, in-situ measurement of the horizontal and vertical polarization characteristics of circularly polarized electromagnetic waves. This method effectively and synchronously completes the testing of circularly polarized antennas, measures the relative phase difference between the two polarization directions, and thereby determines the left-handed and right-handed characteristics of the circularly polarized antenna. This significantly solves the problem of determining left-handed and right-handed polarization characteristics in circularly polarized antenna testing.

Description

Technical Field

[0001] The present invention relates to a near-field test system and method for circularly polarized antenna parameters, and relates to the technical field of electromagnetic wave antenna circular polarization test systems and novel quantum detection within the 100 MHz-1 THz frequency band, and in particular to a circularly polarized antenna or circularly polarized electromagnetic wave test system, circularly polarized parameter testing, and a near-field test system. Background Art

[0002] In modern communication technology, circularly polarized antennas are widely used because of their great advantages in transmission and reception. Circularly polarized antennas have poor sensitivity to directionality, which reduces the directivity requirements for receiving antennas and makes them easier to apply in practice.

[0003] However, real-time, synchronous, in-situ testing of circularly polarized antennas is difficult. Currently, commonly used methods include the rotating source method, the polarization pattern method, and the orthogonal component method. These methods primarily measure the electric field information of the horizontal and vertical polarizations by rotating the circularly polarized antenna under test or the linearly polarized antenna under test, in two separate measurements. These methods cannot be completed in a single test, and the need for two measurements results in long and complex testing times. Furthermore, these methods cannot simultaneously measure the electric field information in both the horizontal and vertical directions. This means that the relative phase of the electric field in both directions cannot be determined, and thus the polarization characteristics of the unknown circularly polarized electromagnetic wave—left-handed or right-handed—cannot be directly determined. Since polarization measurements in both directions require rotating the antenna under test, the position of the antenna under test changes, resulting in non-in-situ testing and resulting in positional errors caused by rotation. The added rotation mechanism increases the complexity of the test system and imposes significant costs. Furthermore, measurements require obtaining both polarization quantities separately, but not in real time, which increases uncertainty in the measurement results.

[0004] If a standard circularly polarized test antenna is used for measurement, the manufacturing requirements for the standard circularly polarized antenna for the test are very high. The directional angles of existing circularly polarized antennas are very small. It is very difficult to achieve a circularly polarized antenna that maintains good axial ratio characteristics in the E-plane and H-plane. At the same time, such an antenna has a large directional error, is difficult to manufacture, and has a high processing cost, which increases the cost of setting up the antenna test system. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide a near-field testing system and method for circularly polarized antenna parameters.

[0006] The technical solution of the present invention is:

[0007] A circularly polarized antenna parameter near-field test system, comprising an 852nm laser 1, an 852nm half-wave plate 2, a PBS spectrometer 3, four common 852nm reflectors 4, an alkali metal atom gas chamber 5, two 509nm reflectors (transmitting 852nm) 6, five common 509nm reflectors 7, an 852nm reflector 8 (transmitting 509nm), an 852nm photodetector 9, an oscilloscope 10, data processing software 11, a 509nm laser 12, a 509nm PBS spectrometer 13, and a 509nm half-wave plate 14.

[0008] The four common 852nm reflectors 4 are respectively a first reflector 4', a second reflector 4", a third reflector 4'" and a fourth reflector 4"";

[0009] Two 509nm reflectors (transmitting 852nm) 6 are the first reflector 6' and the second reflector 6";

[0010] The five common 509nm reflecting mirrors 7 are respectively a first reflecting mirror 7', a second reflecting mirror 7", a third reflecting mirror 7'", a fourth reflecting mirror 7"" and a fifth reflecting mirror 7""';

[0011] The two 852nm photodetectors 9 are a first detector 9' and a second detector 9".

[0012] The invention implements an optical path as follows: laser light from an 852nm laser 1 passes through an 852nm half-wave plate 2 to adjust the polarization direction of the laser light, and the 852nm half-wave plate 2 adjusts the light intensity of the laser light in different polarization directions. The laser light passes through a PBS beam splitter 3, which splits the laser light into two different polarized light paths 1 and polarized light path 2. The polarized light path 1 passes through an ordinary 852nm fourth reflector 4"" and an ordinary 852nm first reflector 4' in sequence for reflection and direction adjustment before entering an alkali metal gas chamber 5. The polarized light path 1 passing through the alkali metal gas chamber 5 passes through a 509nm reflector (852nm transparent) 6", a second reflector 4", and an ordinary 852nm third reflector 4''' to adjust the light path direction before entering an 852nm first detector 9' to obtain a first electrical signal. The obtained first electrical signal enters an oscilloscope 10, and then the electrical signal is transmitted to a data processing software 11 for signal processing.

[0013] The polarized light path 2 coming out of the PBS spectroscope 3 is adjusted in direction by an 852nm reflector (transmits 509nm) 8 and then enters the alkali metal gas chamber 5. The polarized light path 2 passing through the alkali metal gas chamber 5 is adjusted in direction by a 509nm first reflector (transmits 852nm) 6' and then enters an 852nm second detector 9", obtaining a second electrical signal which enters an oscilloscope 10. The obtained second electrical signal is then transmitted to a data processing software 11 for signal processing.

[0014] The laser light emitted from the 509nm laser 12 passes through a 509nm half-wave plate 14 to adjust the polarization of the optical path. The 509nm half-wave plate 14 adjusts the light intensity of the laser light in different polarization directions. The laser light after the light intensity adjustment passes through a PBS beam splitter 13. The PBS beam splitter 13 splits the laser light into two different polarized light paths 3 and a polarized light path 4. The polarized light path 3 passes through a conventional 509nm first reflector 7', a second reflector 7", a third reflector 7'", a fourth reflector 7"" and a fifth reflector 7""' in sequence, and then passes through a second 509nm reflector (transmitting 852nm) 6" to enter the alkali metal gas chamber 5, and propagates in the alkali metal gas chamber 5 in a collinear manner with the polarized light path 1. When the polarized light path 1 and the polarized light path 3 propagate in opposite directions, they are marked as propagation light path 1.

[0015] The polarized light path 4 coming out of the PBS spectrometer 13 passes through the 509nm first reflector 6' (transmits 852nm) and enters the alkali metal gas chamber 5. In the alkali metal gas chamber 5, the polarized light path 4 propagates in opposite directions along the same line. The polarized light path 2 and the polarized light path 4 propagate in opposite directions as the propagating light path 2.

[0016] The circularly polarized antenna parameters are tested in the near field using the test system obtained above. The method is as follows:

[0017] In the first step, the 852nm laser 1 generates a stable probe light in the required frequency band;

[0018] The second step is to generate coupled light with stable frequency and required frequency band through 509nm laser 12, build a circularly polarized auxiliary electromagnetic radiation device, and generate the required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna through a microwave signal generator and an antenna;

[0019] In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal;

[0020] The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the position within the near field range. At the same time, an auxiliary circularly polarized antenna is also placed in the near field area of ​​the antenna to be tested.

[0021] Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line.

[0022] Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals;

[0023] In the seventh step, the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step are extracted. The vertical and horizontal electric field amplitudes and phases obtained by propagation path 1 and propagation path 2 are: E1, E2, φ1, φ2, respectively. That is, the amplitude and phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be tested are obtained through the amplitude and phase information of propagation path 1 and propagation path 2, and the polarization characteristics of the electromagnetic wave are analyzed.

[0024] In the eighth step, the antenna to be tested, placed on a two-dimensional scanning frame, is scanned within the near-field scanning plane. The sampling interval is less than λ / 2 of the wavelength of the electromagnetic wave to be tested, and the sampling size is 15λ×15λ. After plane sampling, the near-field to far-field transformation algorithm is used to obtain the required far-field pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

[0025] The circularly polarized antenna parameters are tested in the far field using the test system obtained above. The method is as follows:

[0026] In the first step, the 852nm laser 1 generates a stable probe light in the required frequency band;

[0027] The second step is to generate coupled light with stable frequency and required frequency band through 509nm laser 12, build a circularly polarized auxiliary electromagnetic radiation device, and generate the required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna through a microwave signal generator and an antenna;

[0028] In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal;

[0029] The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the far field. At the same time, an auxiliary circularly polarized antenna is also placed in the near field of the antenna to be tested.

[0030] Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line.

[0031] Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals;

[0032] The seventh step is to extract the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step. The vertical and horizontal electric field amplitudes and phases obtained by the propagation optical path 1 and the propagation optical path 2 are: E1, E2, φ1, φ2, respectively. When Δφ=φ1-φ2>0, it is left-handed; when Δφ=φ1-φ2<0, it is right-handed, and the axial ratio is calculated by the ratio of E1 and E2, that is, the phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be measured is obtained through the phase information of the propagation optical path 1 and the propagation optical path 2, and then the left-right rotation characteristics of the electromagnetic wave are analyzed; by analyzing the amplitude information of the propagation optical path 1 and the propagation optical path 2, the horizontal and vertical polarization amplitude information of the circularly polarized antenna to be measured is obtained, and then the corresponding axial ratio, radiation pattern, and gain are obtained;

[0033] In the eighth step, the antenna to be tested, which is placed on a two-dimensional scanning frame, is scanned in the far-field scanning plane to obtain the required far-field radiation pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

[0034] Beneficial effects

[0035] (1) The system of the present invention is based on the existing circularly polarized antenna testing technology, which cannot meet the needs of use. Therefore, the present invention, based on the new electromagnetic quantum detection technology, utilizes the coupling relationship between electromagnetic waves and Rydberg atoms, and the relationship between the atomic energy level wave function in the Rydberg state and the response state of electromagnetic waves, cleverly designs the laser path, utilizes the interaction relationship between laser and alkali metal atoms, and utilizes the heterodyne method related to the Rydberg atom measurement of the electromagnetic wave phase, innovatively solves the real-time, in-situ measurement of the horizontal polarization and vertical polarization characteristics of circularly polarized electromagnetic waves, effectively and synchronously completes the test of circularly polarized antennas, and can measure the relative phase difference between the two polarization directions, and then can judge the left-handed and right-handed characteristics of the circular polarization of the antenna, greatly solving the problem of circularly polarized antenna testing in judging the left-handed and right-handed polarization characteristics. Since there is no need to rotate the antenna to be tested, the problem of adding a high-precision rotating shaft mechanism and eliminating the position error caused by the rotation of the antenna to be tested is reduced. At the same time, it also solves the problem of too long test time caused by two measurements in circularly polarized antenna testing. This method can reduce the test time by half.

[0036] (2) The novel circularly polarized test probe proposed in this invention is based on atomic measurement technology and has no significant directivity. This ensures that the directional angle corresponding to the measured circularly polarized low axial ratio is large and the directional error is very small. Based on these advantages, this method provides a new method and system for testing the polarization characteristics and axial ratio parameters of circularly polarized antennas and even circularly polarized electromagnetic waves.

[0037] (3) Since this method is based on the technology of atomic quantum measurement and uses non-metallic materials, it reduces the errors caused by the use of metal probes in traditional tests. For example, the metal probe will cause damage to the test field of the antenna to be tested, affecting the accuracy of the test; the directionality of the metal probe is very obvious, which brings certain directional errors and requires later correction, which brings a certain amount of work; the metal probe mainly measures the current caused by the electromagnetic induction effect. The test principle is non-electromagnetic field traceability test, which leads to great limitations on its test accuracy.

[0038] (4) The present invention mainly utilizes a method based on quantum coherence effect, combines microwave heterodyne method and quantum detection technology and applies it to the field of traditional near-field antenna measurement. For the first time, while synchronously obtaining electromagnetic wave amplitude and phase information, it also obtains circularly polarized electromagnetic wave information such as axial ratio and polarization characteristics in real time. Moreover, due to the synchronous measurement of electromagnetic waves, the properties of electromagnetic waves with circular polarization rotation characteristics at a certain position can be determined, thus making up for the shortcomings of existing circular polarization characteristic antenna measurement. At the same time, the method adopts a non-metallic structure, eliminating the influence of metal probes. At the same time, the method can measure the electromagnetic spectrum range from 100MHz to 1THz, providing a solution for antenna near-field testing in the terahertz band. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the test system of the present invention;

[0040] Figure 2 is the energy level diagram of the Rydberg atom;

[0041] Figure 3 It is a schematic diagram of the specific optical path of the probe;

[0042] Figure 4 It is the absorption test curve of testing two two-way light paths. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of this application more clear, the application will be further described in detail with reference to the accompanying drawings, which are implementation examples. It should be understood that the specific examples described here are only used to explain this application and are not intended to limit this application.

[0044] This invention combines novel quantum microwave detection technology with traditional electromagnetic testing techniques to effectively solve the problem of circularly polarized antenna testing in real time, in situ, and synchronously. It can also distinguish between unknown circular polarization and left-handed polarization characteristics. The specific real-time method is described below.

[0045] like Figure 2-Figure 4 As shown, the frequency-stable detection light generated is split into two laser beams with the same intensity but different polarization directions through an optical fiber device and its beam splitter, and is respectively emitted into the alkali metal gas chamber to excite the alkali metal atoms from the ground state to the intermediate state.

[0046] Through the optical fiber device and its beam splitter, the generated frequency-stable coupled light is divided into two beams of laser light with the same intensity but different polarization directions, which are respectively shot into the alkali metal gas chamber to excite the alkali metal atoms from the intermediate state of cesium atoms to the Rydberg state.

[0047] Specifically, the two frequency-stable probe light and coupling light beams output from the optical fiber are transmitted toward each other to form two laser light paths with similar positions, and are collinearly passed through the alkali metal atom gas chamber. At the same time, polarizers are used to adjust the collinear coupling light and probe light so that they have the same linear polarization direction, and the laser polarization directions corresponding to the two laser light paths are perpendicular to each other.

[0048] Using a microwave radiation device, electromagnetic waves with similar frequencies are radiated separately and radiated toward the position of the alkali metal atom gas chamber, and then superimposed. The two electromagnetic waves generated have different electric field intensities. The two electric fields are superimposed to generate a new beat frequency electric field.

[0049] Through the laser signal receiving and processing device, a corresponding balanced photodetector and oscilloscope are connected to one side of the alkali metal atom gas chamber to absorb the detection light passing through the alkali metal atom gas chamber and convert it into an electrical signal for processing and storage.

[0050] The electromagnetic wave frequency band to be measured ranges from 100MHz to 1THz. By utilizing the different shapes of Rydberg state wave functions to have different sensitivities to the polarization of electromagnetic waves, a circularly polarized antenna parameter measurement and near-field test system using Rydberg atoms is established to measure them in real time and synchronously.

[0051] Electromagnetic waves of different frequencies correspond to different Rydberg atomic energy levels, such as Figure 2 As shown;

[0052] The new electromagnetic probe used in this test method is independent of the wavelength of the antenna being tested, relying solely on the energy level of the alkali metal atoms being excited. This is an atomic detection technology. Therefore, at low frequencies, the probe can be significantly smaller than the wavelength being tested. At terahertz frequencies, the probe can be significantly larger than the wavelength being tested, thus resolving the processing challenges inherent in the terahertz band.

[0053] This method can achieve real-time synchronization and complete polarization tests in different directions without rotating the probe (i.e., polarization rotation). It only requires adjusting the polarization directions of the two lasers passing through the alkali metal atoms separately and ensuring that the polarization directions of the two lasers are perpendicular to each other and the light intensity is the same.

[0054] Based on the Rydberg atom circularly polarized antenna near-field test system, the method includes: an alkali metal gas chamber and its optical fiber system, a laser generation and frequency locking device, a microwave radiation device, and a signal collection device, with a simple structure and easy operation.

[0055] A frequency-stable probe laser is generated by a probe light laser device, and the light is directly coupled into the alkali metal gas cell using an optical fiber device, thereby exciting the alkali metal atoms from the ground state to the intermediate state.

[0056] A frequency-stable probe laser is generated by coupling an optical laser device, and the light is directly coupled into the alkali metal gas cell using an optical fiber device, thereby exciting the alkali metal atoms from an excited state to a Rydberg state.

[0057] A microwave radiation device is constructed, and the required electromagnetic waves to be measured and auxiliary electromagnetic waves are generated through a signal generator and an antenna. A signal receiving device is connected to a corresponding photodetector and oscilloscope on one side of the alkali metal atom gas chamber to convert the transmission of the alkali metal atoms to the detection laser into an electrical signal and record it. Using the microwave radiation device, electromagnetic waves of similar frequencies are radiated and directed toward the position of the alkali metal atom gas chamber, and superimposed. The two electromagnetic waves generated have different electric field intensities, and these two electromagnetic waves generate a low-frequency beat signal. Through the signal receiving device, the intensity of the detection light after passing through the alkali metal atom gas chamber can be received, detected, and recorded. This new Rydberg probe is scanned in the near field, and the information of each sampling point is recorded. The low-frequency sinusoidal signal obtained by the oscilloscope is fitted to extract the amplitude and initial phase of the curve, and the intensity and phase information of the required electromagnetic wave electric field component are obtained.

[0058] Using the microwave heterodyne method, two laser beams, each with two collinear beams facing each other and having the same linear polarization, are directed to different positions of the alkali metal gas chamber, while the polarization directions of the two laser beams are perpendicular to each other. Specifically, for any laser light path, the probe light can excite the alkali metal atoms from the ground state to the excited state, and the coupling light can excite the alkali metal atoms in the excited state to the Rydberg state. The atoms in the Rydberg state are then coupled to the superposition field of the external electromagnetic wave to be measured and the auxiliary electromagnetic wave (referred to as the field to be measured and the auxiliary field) to complete the measurement of the electromagnetic wave, and directly obtain the test of the amplitude and phase information of the electromagnetic wave. Furthermore, when the alkali metal atoms in the Rydberg state are excited by different laser polarization directions, the coupling strength between the alkali metal atoms and the electromagnetic wave is related to the wave function shape of the Rydberg state. When the shape of the wave function is symmetrically distributed, different laser polarization directions are insensitive to the polarization direction of the electromagnetic wave. When the shape of the wave function is asymmetric, the laser polarization direction is sensitive to the polarization direction of the electromagnetic wave. Therefore, by utilizing the symmetric and asymmetric characteristics of the wave function shape, the polarization characteristics of the laser and the optical path design are cleverly adjusted to complete the test of electromagnetic waves in different polarization directions. This test method effectively solves the problem that the existing circularly polarized antenna test cannot complete the test of different polarization directions synchronously; it solves the problem that the existing circularly polarized antenna needs pre-calibration technology to complete the judgment of the left and right polarization directions of the antenna; it also solves the problem of real-time and in-situ testing of circularly polarized antennas (no need to rotate to change the position of the antenna to be tested); it solves the problem of test time complexity caused by the need to measure the electric field information of the two polarization directions twice in the circular polarization antenna test, and reduces the test time by at least half; it proposes a new method and system for the measurement of circularly polarized antenna and even circularly polarized electromagnetic wave parameters. This method uses heterodyne technology and according to the amplitude of the heterodyne result A∝E∝T probe , the amplitude of the signal measured at the two polarization positions is A1, A2, the phase is φ1, φ2, then the corresponding two polarization phases φ=φ1-φ2, the axial ratio Such a method does not require additional auxiliary calibration and additional test equipment for subsequent numerical compensation.

[0059] Microwave heterodyne method principle description:

[0060] For the applied electric field E1 to be measured and the auxiliary field E2, their superposition field at the position of the gas chamber is E total , the relationship between the superposition field and the transmittance of the probe laser through the gas cell is as follows,

[0061]

[0062] The frequency of the electromagnetic wave to be measured is ω V =2πf V , the frequency of the auxiliary electromagnetic wave ω H =2πf H, the phase difference between the electromagnetic wave to be measured and the auxiliary electromagnetic wave is Δφ=φ V -φ H , the electric field of the electromagnetic wave to be measured E1=E V cos(ω V t+f V ), the electric field of the auxiliary electromagnetic wave E2=E H cos(ω H t+φ H ). In this way, we can measure the amplitude and phase information of the electromagnetic wave to be measured based on the transmittance of the detection laser.

[0063] The present invention mainly utilizes a method based on quantum coherence effect microwave heterodyne method to apply quantum detection technology to the field of traditional near-field antenna measurement. For the first time, while synchronously obtaining electromagnetic wave amplitude and phase information, it also obtains circularly polarized electromagnetic wave information in real time. Moreover, because the different polarization characteristics of the synchronously measured circularly polarized electromagnetic waves are used to determine the electromagnetic wave properties of the circular polarization rotation characteristics at a certain position, this method overcomes the shortcomings of existing circular polarization characteristic antenna measurement. At the same time, the method adopts non-metallic structure, which reduces the problem of the measured electric field distribution being destroyed due to the use of metal structure in existing antenna testing, reduces the problem of multiple reflection in antenna testing, and reduces the problem of directional error in traditional waveguide. At the same time, the method can measure the electromagnetic spectrum range from 100MHz to 1THz, providing a solution for near-field testing of antennas in the terahertz frequency band. At the same time, the method is also very convenient in measuring the axial ratio characteristics of circular polarization, and does not require an additional auxiliary polarizer for reference and subsequent numerical comparison calculation.

[0064] Step 1: Use fiber lens and polarization-maintaining fiber to couple the laser output from the laser and transmitted in space into the optical fiber, so as to minimize the loss of laser and increase the flexibility of laser use.

[0065] Step 2: Use optical components to split the laser output from the light into two paths, adjust the polarizers of the two light paths so that the two lasers have mutually perpendicular polarization directions, and at the same time keep the light intensity of the two paths consistent. The two lasers pass through different positions of the cesium atom gas chamber, but the two positions are close to each other.

[0066] Step 3: Turn on the laser output and frequency locking device, stabilize the detector wavelength at around 852nm, and change the cesium atom from the ground state 6S 1 / 2 Excited to the intermediate state 6P 3 / 2 , stabilize the coupling light wavelength at around 509nm, and 3 / 2 The atoms are excited to 60D 5 / 2 .

[0067] Step 4: Place two photodetectors on each side of the cesium atom gas cell and connect them to different channels of the oscilloscope. The two photodetectors are used to receive the detection light from the two light channels, respectively, to characterize the absorption of the two laser detection lights by the gas cell, and to convert the optical signals into electrical signals.

[0068] Step 5: Place the circularly polarized antenna to be tested on a two-dimensional scanning frame, and position the antenna to be tested perpendicular to the air chamber within the near field range. At the same time, place an auxiliary circularly polarized antenna in the near field area of ​​the antenna to be tested.

[0069] Step 6: Connect the antenna to be tested and the auxiliary circularly polarized antenna to the corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial cable.

[0070] Step 7: The electrical signal obtained in step 4 is output to the oscilloscope, and an external 1KHz sine wave signal is used as the trigger signal of the receiving channel in the oscilloscope, so as to obtain a stable electrical signal absorption spectrum.

[0071] Step 8: By extracting the curve parameters of the signal in step 7, the amplitude and phase information of the corresponding electromagnetic wave to be measured are obtained. The vertical and horizontal electric field amplitudes and phases obtained by the two lasers are: E1, E2, φ1, φ2 respectively.

[0072] Step 9: By analyzing the phase information of the two signals in Step 8, the relative phase relationship between the horizontal and vertical polarization components of the circularly polarized antenna under test in Step 5 is obtained, and the left-hand and right-hand characteristics of the electromagnetic wave are analyzed. When Δφ = φ1 - φ2 > 0, it is left-handed; when Δφ = φ1 - φ2 < 0, it is right-handed. Using the amplitude information extracted in Step 8, the horizontal and vertical polarization amplitude information of the circularly polarized antenna under test is obtained, and the corresponding axial ratio, radiation pattern, gain, etc. are obtained.

[0073] Step 9: Scan the antenna to be tested placed on a two-dimensional scanning frame within the near-field scanning plane. The sampling interval is less than λ / 2 of the wavelength of the electromagnetic wave to be tested, and the sampling size is 15λ×15λ. After plane sampling, the required far-field pattern is obtained using the near-field to far-field transformation algorithm.

[0074] Example

[0075] like Figure 1As shown, a circularly polarized antenna parameter near-field test system comprises a detection light laser 1, a detection light half-wave plate 2, a detection light PBS spectrometer 3, four detection light reflectors 4, an alkali metal atom gas chamber 5, two coupling light reflectors 6, five coupling light reflectors 7, a detection light reflector 8, two detection light photodetectors 9, a coupling light laser 12, a coupling light PBS spectrometer 13, and a coupling light half-wave plate 14; the detection light reflector 8 is capable of transmitting the coupling light;

[0076] The four detection light reflecting mirrors 4 are respectively a first reflecting mirror 4', a second reflecting mirror 4", a third reflecting mirror 4'" and a fourth reflecting mirror 4"";

[0077] The two coupling light reflectors 6 are a first reflector 6' and a second reflector 6".

[0078] The five coupling light reflecting mirrors 7 are respectively a first reflecting mirror 7', a second reflecting mirror 7", a third reflecting mirror 7'", a fourth reflecting mirror 7"" and a fifth reflecting mirror 7'"";

[0079] The two detection light photodetectors 9 are a first detector 9' and a second detector 9".

[0080] The laser light emitted from the detection light laser 1 passes through the detection light half-wave plate 2 to adjust the polarization direction of the laser light. The detection light half-wave plate 2 adjusts the light intensity of the laser light in different polarization directions. The laser light passes through the detection light PBS spectrometer 3, which splits the laser light into two different polarization light paths 1 and polarization light path 2. The polarized light path 1 is reflected and adjusted in direction by the fourth reflector 4"" and the first reflector 4' in sequence, and then enters the alkali metal gas chamber 5. The polarized light path 1 that has passed through the alkali metal gas chamber 5 is adjusted in direction by the second reflector 6", the second reflector 4", and the third reflector 4'" in sequence, and then enters the first detector 9' to obtain a first electrical signal.

[0081] The polarized light path 2 coming out of the detection light PBS spectrometer 3 is adjusted in direction by the detection light reflector 8 and then enters the alkali metal gas chamber 5. The polarized light path 2 passing through the alkali metal gas chamber 5 is adjusted in direction by the first reflector 6' and then enters the second detector 9" to obtain a second electrical signal.

[0082] The laser light emitted from the coupled light laser 12 passes through the coupled light half wave plate 14 to adjust the polarization of the optical path. The coupled light half wave plate 14 adjusts the light intensity of the laser light in different polarization directions. The laser light after the light intensity adjustment passes through the coupled light PBS spectrometer 13. The coupled light PBS spectrometer 13 splits the laser light into two different polarized light paths 3 and polarized light path 4. The polarized light path 3 passes through the first reflector 7', the second reflector 7", the third reflector 7'", the fourth reflector 7"" and the fifth reflector 7""' in sequence, and then passes through the second reflector 6" to enter the alkali metal gas chamber 5, and propagates in the alkali metal gas chamber 5 in the same line as the polarized light path 1. When the polarized light path 1 and the polarized light path 3 propagate in opposite directions, they are marked as propagation light path 1.

[0083] The polarized light path 4 coming out of the coupled light PBS spectrometer 13 passes through the first reflector 6' and enters the alkali metal gas chamber 5. In the alkali metal gas chamber 5, the polarized light path 2 propagates in opposite directions on the same line. When the polarized light path 2 and the polarized light path 4 propagate in opposite directions, they are marked as propagation light path 2.

[0084] 2. The circularly polarized antenna parameter near-field test system according to claim 1, characterized in that:

[0085] The wavelength of the detection light laser 1 is 852 nm.

[0086] 3. The circularly polarized antenna parameter near-field test system according to claim 1, characterized in that:

[0087] The wavelength of the coupling light laser 12 is 509 nm.

[0088] 4. A method for performing near-field testing on circularly polarized antenna parameters using the test system according to any one of claims 1 to 3, characterized in that the steps include:

[0089] The first step is to generate a probe light with a stable frequency and a required frequency band through the probe light laser 1;

[0090] The second step is to generate coupled light with stable frequency and required frequency band through the coupled optical laser 12, build a circularly polarized auxiliary electromagnetic radiation device, and generate the required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna through the microwave signal generator and antenna;

[0091] In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal;

[0092] The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the position within the near field range. At the same time, an auxiliary circularly polarized antenna is also placed in the near field area of ​​the antenna to be tested.

[0093] Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line.

[0094] Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals;

[0095] In the seventh step, the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step are extracted. The vertical and horizontal electric field amplitudes and phases obtained by propagation path 1 and propagation path 2 are: E1, E2, φ1, φ2, respectively. That is, the amplitude and phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be tested are obtained through the amplitude and phase information of propagation path 1 and propagation path 2, and the polarization characteristics of the electromagnetic wave are analyzed.

[0096] In the eighth step, the antenna to be tested, placed on a two-dimensional scanning frame, is scanned within the near-field scanning plane. The sampling interval is less than λ / 2 of the wavelength of the electromagnetic wave to be tested, and the sampling size is 15λ×15λ. After plane sampling, the near-field to far-field transformation algorithm is used to obtain the required far-field pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

[0097] 5. A method for performing near-field testing on circularly polarized antenna parameters using the test system according to any one of claims 1 to 3, characterized in that the steps include:

[0098] In the first step, the 852nm laser 1 generates a stable probe light in the required frequency band;

[0099] The second step is to generate coupled light with stable frequency and required frequency band through 509nm laser 12, build a circularly polarized auxiliary electromagnetic radiation device, and generate the required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna through a microwave signal generator and an antenna;

[0100] In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal;

[0101] The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the far field. At the same time, an auxiliary circularly polarized antenna is also placed in the near field of the antenna to be tested.

[0102] Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line.

[0103] Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals;

[0104] The seventh step is to extract the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step. The vertical and horizontal electric field amplitudes and phases obtained by the propagation optical path 1 and the propagation optical path 2 are: E1, E2, φ1, φ2, respectively. When Δφ=φ1-φ2>0, it is left-handed; when Δφ=φ1-φ2<0, it is right-handed, and the axial ratio is calculated by the ratio of E1 and E2, that is, the phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be measured is obtained through the phase information of the propagation optical path 1 and the propagation optical path 2, and then the left-right rotation characteristics of the electromagnetic wave are analyzed; by analyzing the amplitude information of the propagation optical path 1 and the propagation optical path 2, the horizontal and vertical polarization amplitude information of the circularly polarized antenna to be measured is obtained, and then the corresponding axial ratio, radiation pattern, and gain are obtained;

[0105] In the eighth step, the antenna to be tested, which is placed on a two-dimensional scanning frame, is scanned in the far-field scanning plane to obtain the required far-field radiation pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

Claims

1. A circularly polarized antenna parameter near-field test system, characterized by: The test system comprises a detection light laser (1), a detection light half-wave plate (2), a detection light PBS spectroscope (3), four detection light reflectors (4), an alkali metal atom gas chamber (5), two coupling light reflectors (6), five coupling light reflectors (7), a detection light reflector (8), two detection light photodetectors (9), a coupling light laser (12), a coupling light PBS spectroscope (13), and a coupling light half-wave plate (14); the detection light reflector (8) is capable of transmitting the coupling light; The four detection light reflecting mirrors (4) are respectively a 41st reflecting mirror (4'), a 42nd reflecting mirror (4"), a 43rd reflecting mirror (4'"), and a 44th reflecting mirror (4""); The two coupling light reflectors (6) are respectively a sixth first reflector (6') and a sixth second reflector (6"); The five coupling light reflecting mirrors (7) are respectively a seventy-first reflecting mirror (7'), a seventy-second reflecting mirror (7"), a seventy-third reflecting mirror (7'"), a seventy-fourth reflecting mirror (7") and a seventy-fifth reflecting mirror (7'""); The two detection light photoelectric detectors (9) are respectively a first detector (9') and a second detector (9"); The laser light from the detection light laser (1) is adjusted in polarization direction by passing through the detection light half wave plate (2). The detection light half wave plate (2) adjusts the light intensity of the laser light in different polarization directions. The laser light is then passed through the detection light PBS spectroscope (3). The detection light PBS spectroscope (3) splits the laser light into two different polarization light paths 1 and polarization light path 2. The polarization light path 1 is reflected and adjusted in direction by the fourth fourth reflector (4") and the fourth first reflector (4') in sequence and then enters the alkali metal gas chamber (5). The polarization light path 1 that has passed through the alkali metal gas chamber (5) is adjusted in direction by passing through the sixth second reflector (6"), the fourth second reflector (4"), and the fourth third reflector (4') in sequence and then enters the first detector (9') to obtain a first electrical signal. The polarized light path 2 coming out of the detection light PBS spectroscope (3) enters the alkali metal gas chamber (5) after the direction of the light path is adjusted by the detection light reflector (8). The polarized light path 2 passing through the alkali metal gas chamber (5) enters the second detector (9") after the direction is adjusted by the sixth reflector (6') to obtain a second electrical signal. The laser light emitted from the coupling light laser (12) is adjusted for polarization of the optical path by passing through the coupling light half wave plate (14). The coupling light half wave plate (14) adjusts the light intensity of the laser light in different polarization directions. The laser light after the light intensity adjustment passes through the coupling light PBS spectrometer (13). The coupling light PBS spectrometer (13) splits the laser light into two different polarization light paths 3 and polarization light path 4. The polarization light path 3 passes through the seventh first reflector (7'), the seventh second reflector (7"), the seventh third reflector (7'"), the seventh fourth reflector (7'") and the seventh fifth reflector (7'") in sequence and then passes through the sixth second reflector (6") to enter the alkali metal gas chamber (5). In the alkali metal gas chamber (5), the polarization light path 1 propagates in the same line as the polarization light path 1 in opposite directions. When the polarization light path 1 and the polarization light path 3 propagate in opposite directions, they are marked as propagation light path 1. The polarized light path 4 coming out of the coupled light PBS spectrometer (13) enters the alkali metal gas chamber (5) through the sixth reflector (6'), and propagates in opposite directions with the polarized light path 2 in the alkali metal gas chamber (5). When the polarized light path 2 and the polarized light path 4 propagate in opposite directions, they are marked as propagation light path 2.

2. The circularly polarized antenna parameter near-field test system according to claim 1, wherein: The wavelength of the detection light laser (1) is 852 nm.

3. The circularly polarized antenna parameter near-field test system according to claim 1, wherein: The wavelength of the coupled light laser (12) is 509 nm.

4. A method for performing near-field testing of circularly polarized antenna parameters using the test system according to any one of claims 1 to 3, characterized in that Steps include In the first step, a probe light laser (1) is used to generate a probe light with a stable frequency and a required frequency band; In the second step, a coupled light with a stable frequency and a required frequency band is generated by a coupled light laser (12), a circularly polarized auxiliary electromagnetic radiation device is built, and a microwave signal generator and an antenna are used to generate the required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna; In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal; The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the position within the near field range. At the same time, an auxiliary circularly polarized antenna is also placed in the near field area of ​​the antenna to be tested. Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line. Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals; In the seventh step, the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step are extracted. The vertical and horizontal electric field amplitudes and phases obtained by propagation path 1 and propagation path 2 are: E1, E2, φ1, φ2, respectively. That is, the amplitude and phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be tested are obtained through the amplitude and phase information of propagation path 1 and propagation path 2, and the polarization characteristics of the electromagnetic wave are analyzed. In the eighth step, the antenna to be tested, which is placed on a two-dimensional scanning frame, is scanned in the near-field scanning plane. The sampling interval is less than λ / 2 of the wavelength of the electromagnetic wave to be tested, and the sampling size is 15λ×15λ. After plane sampling, the near-field to far-field transformation algorithm is used to obtain the required far-field radiation pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

5. A method for performing near-field testing of circularly polarized antenna parameters using the test system according to any one of claims 1 to 3, characterized in that the steps include: In the first step, a 852nm laser (1) is used to generate a probe light with a stable frequency and a required frequency band; In the second step, a 509 nm laser (12) is used to generate coupled light with a stable frequency and a required frequency band, and a circularly polarized auxiliary electromagnetic radiation device is built. The required electromagnetic wave with circular polarization characteristics to be measured and any type of circularly polarized electromagnetic wave generated by the auxiliary circularly polarized antenna are generated by a microwave signal generator and an antenna; In the third step, the detection light generated in the first step and the coupled light generated in the second step pass through the test system to generate a first electrical signal and a second electrical signal; The fourth step is to place the circularly polarized antenna to be tested on a two-dimensional scanning frame, with the antenna to be tested and the gas chamber perpendicular to the far field. At the same time, an auxiliary circularly polarized antenna is also placed in the near field of the antenna to be tested. Step 5: Connect the circularly polarized antenna to be tested and the auxiliary circularly polarized antenna to corresponding signal generators respectively. The frequency difference between the electromagnetic waves radiated by the circularly polarized antenna to be tested and the auxiliary antenna is 1 kHz. The signal generators connected to the two antennas are synchronized using a coaxial line. Step 6: Output the first and second electrical signals obtained in step 3 to an oscilloscope, and use an external 1 kHz sine wave signal as a trigger signal for a receiving channel in the oscilloscope, thereby obtaining stable absorption spectra of the first and second electrical signals; The seventh step is to extract the amplitude and phase information of the electromagnetic waves of the first electric signal absorption spectrum and the second electric signal absorption spectrum obtained in the sixth step. The vertical and horizontal electric field amplitudes and phases obtained by the propagation optical path 1 and the propagation optical path 2 are: E1, E2, φ1, φ2, respectively. When Δφ=φ1-φ2>0, it is left-handed; when Δφ=φ1-φ2<0, it is right-handed, and the axial ratio is calculated by the ratio of E1 and E2, that is, the phase information of the horizontal and vertical polarization components of the circularly polarized antenna to be measured is obtained through the phase information of the propagation optical path 1 and the propagation optical path 2, and then the left-right rotation characteristics of the electromagnetic wave are analyzed; by analyzing the amplitude information of the propagation optical path 1 and the propagation optical path 2, the horizontal and vertical polarization amplitude information of the circularly polarized antenna to be measured is obtained, and then the corresponding axial ratio, radiation pattern, and gain are obtained; In the eighth step, the antenna to be tested, which is placed on a two-dimensional scanning frame, is scanned in the far-field scanning plane to obtain the required far-field radiation pattern of the circularly polarized antenna and the corresponding axial ratio, radiation pattern, and gain.

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