A near-field test device and method for electrical performance of terahertz antenna and radome

Abstract

The present invention discloses a near-field test device and method for electrical performance of a terahertz antenna and a radome, wherein the device comprises a vector network analyzer, a multi-degree-of-freedom turntable, a low-noise amplifier, a first receiving module, a second receiving module, a signal distribution module, a local oscillator source, a transmitting source, a switch, a computer and an I / O interface card, a coupler, a two-dimensional scanning frame, a polarization rotator, a scanning probe, a terahertz antenna, and a radome. The present invention adopts a link coupling method to collect reference signals, which can improve the stability of the reference signals and ensure the measurement accuracy of the phase. The present invention adopts a polarization rotator method to collect near-field electric field components, which avoids the positioning error caused by the rotating polarization probe and is conducive to improving the test accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of antenna and radome electrical performance testing, and in particular to a terahertz antenna and radome electrical performance near-field testing device. Background Art

[0002] The frequency range of terahertz waves is 100GHz to 10THz. Its wavelength overlaps with microwave and millimeter waves in the low frequency band and with infrared band in the high frequency band. It is located at the intersection of electronics and photonics. Terahertz communication has the characteristics of large channel capacity, high resolution and good directivity. As a component for transmitting and receiving electromagnetic waves, terahertz antenna provides the required coupling between the transmitter or receiver and the medium that propagates radio waves. Its electrical performance indicators will significantly affect the ability of terahertz communication. At present, the main testing methods for terahertz antennas include far-field method, compact field method and near-field method. The near-field method has been increasingly studied due to its advantages such as small footprint and low cost.

[0003] In addition, in near-field measurement, it is necessary to collect two orthogonal electric field components for near-field and far-field transformation. The commonly used method is to rotate the scanning probe 90° forward or reversely. However, the diameter of the probe is small in the terahertz frequency band. Due to the positioning accuracy of the rotating mechanism and the processing accuracy of the probe, additional positioning errors can be introduced during the rotation process, resulting in increased measurement uncertainty. Summary of the invention

[0004] The object of the present invention is to provide a near-field testing device and method for the electrical performance of a terahertz antenna and a radome, which can realize accurate collection of terahertz reference signals, thereby ensuring the accuracy of performance data.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] A near-field test device for electrical performance of a terahertz antenna and a radome, comprising a vector network analyzer, a multi-degree-of-freedom turntable, a low-noise amplifier, a first receiving module, a second receiving module, a signal distribution module, a local oscillator source, a transmitting source, a switch, a computer and an I / O interface card, a coupler, a two-dimensional scanning frame, a polarization rotator, a scanning probe, a terahertz antenna, and a radome, wherein:

[0007] A radome to be tested is installed outside the terahertz antenna, and the radome and the antenna are installed together on a multi-degree-of-freedom turntable; the terahertz antenna is connected to a vector network analyzer through a low-noise amplifier, a second receiving module, and a signal distribution module, and a local oscillator source provides a local oscillator signal to the signal distribution module, and the vector network analyzer and the local oscillator source are connected through a BNC cable; a computer is connected to the local oscillator source and the vector network analyzer through a switch, triggers and controls the vector network analyzer and the local oscillator source, and collects data from the vector network analyzer;

[0008] The two-dimensional scanning frame is arranged in front of the terahertz antenna, and is an inverted T-shaped structure, including an X-axis and a Y-axis; the polarization rotator is installed on the scanning probe, and the scanning probe is installed on the Y-axis; the scanning probe is connected to the frequency multiplication source module and the first receiving module through a coupler, and the first receiving module is connected to the signal distribution module; the computer is connected to the transmitting source through the I / O interface board, and controls the transmitting source to output the terahertz signal to the scanning probe and the first receiving module through the frequency multiplication source module and the coupler, and the scanning probe transmits the terahertz signal as a test signal and receives it through the terahertz antenna;

[0009] The signal distribution module multiplies the local oscillator signal provided by the local oscillator source and sends it to the first receiving module and the second receiving module. The first receiving module uses the terahertz signal as a reference signal to mix and down-convert the local oscillator signal to obtain a reference intermediate frequency signal and sends it to the signal distribution module. The signal distribution module amplifies the intermediate frequency signal and sends it to the network vector analyzer.

[0010] The test signal received by the terahertz antenna is amplified by a low-noise amplifier, mixed and down-converted with the local oscillator signal through the second receiving module, and a test intermediate frequency signal is obtained and sent to the signal distribution module. The signal distribution module amplifies the test intermediate frequency signal and sends it to the network vector analyzer; the network vector analyzer performs coherent processing on the test intermediate frequency signal and the reference intermediate frequency signal to obtain the horizontal component electric field and the vertical component electric field and output them to the computer.

[0011] Furthermore, the reference signal is collected by link direct coupling, and the signal path is sequentially a transmitting source, a radio frequency cable, a frequency multiplication source module, a coupler, a first receiving module, a signal distribution module, a vector network analyzer, and a computer.

[0012] Furthermore, when it is necessary to measure the horizontal component electric field of the terahertz signal, there is no need to install a polarization rotator on the scanning probe, and the test signal can be directly transmitted through the scanning probe; when it is necessary to measure the vertical component electric field of the terahertz signal, it is necessary to install a polarization rotator, which is used to rotate the polarization of the test signal emitted by the scanning probe by 90°.

[0013] Furthermore, the terahertz antenna is fixed to the antenna base, and the antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable, and it is ensured that the rotation axis of the antenna coincides with the rotation axis of the azimuth table.

[0014] Furthermore, the pitch axis of the multi-degree-of-freedom turntable is made to coincide with the pitch axis of the antenna by adjusting the pitch, up-down, and front-back positions of the azimuth table.

[0015] Furthermore, the directional pattern compensation data of the scanning probe and the compensation data of the polarization rotator are obtained through theoretical simulation or calibration of the scanning probe. Based on the compensation data and the horizontal component electric field and the vertical component electric field output by the network vector analyzer, the far-field directional pattern of the antenna and the radome is obtained using a near-far-field transformation algorithm.

[0016] Furthermore, the electrical performance parameters of the radome are obtained by comparing the far-field radiation patterns of the antenna and the radome, including power transmission efficiency, sidelobe level elevation, beam width change, etc.

[0017] A near-field test method for electrical performance of a radome of a terahertz antenna, comprising:

[0018] Step 1, the scanning probe is installed on the Y axis of the two-dimensional scanning frame, connected to the coupler and the frequency doubling source module through a waveguide, the frequency doubling source is connected to the transmitting source through a radio frequency cable, the coupling end of the coupler is connected to the first receiving module through a waveguide, and the first receiving module is connected to the signal distribution module through a radio frequency cable;

[0019] Step 2, the scanning probe is not equipped with a polarization rotator;

[0020] Step 3: The terahertz antenna is installed on the antenna base and its polarization is kept consistent with that of the scanning probe. The antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable to ensure that the rotation axis of the antenna coincides with the azimuth rotation axis of the turntable. The pitch axis of the multi-degree-of-freedom turntable is made to coincide with the pitch axis of the antenna base by adjusting the pitch, up and down, front and back axis systems.

[0021] Step 4, the output end of the antenna to be tested is connected to the low noise amplifier and the second receiving module through a waveguide, and the second receiving module is connected to the signal distribution module through a radio frequency cable;

[0022] Step 5, the reference signal channel and the test signal channel of the signal distribution module are connected to the intermediate frequency receiving port of the vector network analyzer through a radio frequency cable;

[0023] Step 6, calculate and set the scanning range of the scanning probe on the X-axis of the scanning frame according to the confidence angle of the radiation pattern and the height of the antenna cover; control the antenna base so that the test angle is (α, β), move the turntable azimuth to -α, and adjust the multi-degree-of-freedom turntable so that the antenna aperture is parallel to the scanning probe aperture;

[0024] Step 7: Use the terahertz antenna to measure the horizontal component electric field E of the test signal. x Conduct data collection;

[0025] Step 8: Install a polarization rotator on the probe to measure the vertical component of the electric field E of the test signal through the terahertz antenna. y Conduct data collection;

[0026] Step 9: Install the radome to be tested on the terahertz antenna and collect the horizontal component electric field E with the radome. x and the vertical component of the electric field E y ;

[0027] Step 10, for both cases where the radome is not installed and where the radome is installed, based on the compensation data and the horizontal component electric field and the vertical component electric field output by the network vector analyzer, a near-far field transformation algorithm is used to obtain the far-field directivity patterns of the antenna and the radome respectively;

[0028] Step 11, obtaining the electrical performance parameters of the radome by comparing the far-field radiation patterns of the antenna and the radome.

[0029] Furthermore, the scanning step of the X-axis and the Y-axis is less than 1 / 2 the wavelength of the terahertz wave; wherein the calculation formula of the scanning range L is: L=2·h·tanθ+d, wherein h is the height of the antenna cover, θ is the confidence angle of the radiation pattern, and d is the lateral dimension of the probe.

[0030] Compared with the prior art, the present invention has the following technical features:

[0031] Compared with the existing test methods, the present invention adopts the link coupling method to collect the reference signal, which can improve the stability of the reference signal and ensure the measurement accuracy of the phase. The present method adopts the polarization rotator method to collect the near-field electric field component, avoiding the positioning error caused by the rotating polarization probe, which is conducive to improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention. DETAILED DESCRIPTION

[0033] See also Figure 1 The present invention provides a near-field test device for electrical properties of a terahertz antenna and a radome, comprising a vector network analyzer, a multi-degree-of-freedom turntable, an antenna base, a low-noise amplifier, a first receiving module, a second receiving module, a signal distribution module, a local oscillator source, a transmitting source, a switch, a computer and an I / O interface card, a coupler, a two-dimensional scanning frame, a polarization rotator, a waveguide and a radio frequency cable, a scanning probe, a terahertz antenna, and a radome, wherein:

[0034] A radome to be tested is installed outside the terahertz antenna, and the radome and the antenna are installed together on a multi-degree-of-freedom turntable; the terahertz antenna is connected to a vector network analyzer through a low-noise amplifier, a second receiving module, and a signal distribution module, and a local oscillator source provides a local oscillator signal to the signal distribution module, and the vector network analyzer and the local oscillator source are connected through a BNC cable; a computer is connected to the local oscillator source and the vector network analyzer through a switch, triggers and controls the vector network analyzer and the local oscillator source, and collects data from the vector network analyzer.

[0035] The two-dimensional scanning frame is arranged in front of the terahertz antenna, and is an inverted T-shaped structure, including an X-axis and a Y-axis; the polarization rotator is installed on the scanning probe, and the scanning probe is installed on the Y-axis, and the Y-axis can move along the X-axis; the scanning probe is connected to the frequency multiplication source module and the first receiving module through a coupler, and the first receiving module is connected to the signal distribution module; the computer is connected to the transmitting source through the I / O interface board, and controls the transmitting source to output the terahertz signal to the scanning probe and the first receiving module through the frequency multiplication source module and the coupler, and the scanning probe transmits the terahertz signal as a test signal and receives it through the terahertz antenna;

[0036] The signal distribution module multiplies the local oscillator signal provided by the local oscillator source and sends it to the first receiving module and the second receiving module. The first receiving module uses the terahertz signal as a reference signal to mix and down-convert the local oscillator signal to obtain a reference intermediate frequency signal and sends it to the signal distribution module. The signal distribution module amplifies the intermediate frequency signal and sends it to the network vector analyzer.

[0037] The test signal received by the terahertz antenna is amplified by a low-noise amplifier, mixed and down-converted with the local oscillator signal through the second receiving module, and a test intermediate frequency signal is obtained and sent to the signal distribution module. The signal distribution module amplifies the test intermediate frequency signal and sends it to the network vector analyzer; the network vector analyzer performs coherent processing on the test intermediate frequency signal and the reference intermediate frequency signal to obtain the horizontal component electric field and the vertical component electric field and output them to the computer.

[0038] In this scheme, the reference signal is collected by link direct coupling, and the signal path is the transmitting source, RF cable, frequency multiplication source module, coupler, first receiving module, signal distribution module, vector network analyzer, and computer.

[0039] In this solution, when it is necessary to measure the horizontal component electric field of the terahertz signal, there is no need to install a polarization rotator on the scanning probe, and the test signal is directly transmitted through the scanning probe; when it is necessary to measure the vertical component electric field of the terahertz signal, it is necessary to install a polarization rotator, which is used to rotate the polarization of the test signal emitted by the scanning probe by 90°.

[0040] In the above technical solution, the terahertz antenna is fixed to the antenna base, the antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable, and the rotation axis of the antenna is ensured to coincide with the rotation axis of the azimuth table. The pitch axis of the multi-degree-of-freedom turntable is made to coincide with the pitch axis of the antenna by adjusting the pitch, up and down, and front and back positions of the azimuth table.

[0041] The directional pattern compensation data of the scanning probe and the compensation data of the polarization rotator are obtained through theoretical simulation or calibration of the scanning probe. Based on the compensation data and the horizontal component electric field and the vertical component electric field output by the network vector analyzer, the far-field directional pattern of the antenna and the radome is obtained using a near-far-field transformation algorithm.

[0042] By comparing the far-field radiation patterns of the antenna and the radome, the electrical performance parameters of the radome are obtained, including power transmission efficiency, sidelobe level elevation, beam width change, etc.

[0043] On the basis of the above technical solution, the present invention also provides a near-field test method for the electrical performance of a radome of a terahertz antenna, comprising:

[0044] Step 1, the scanning probe is installed on the Y axis of the two-dimensional scanning frame, connected to the coupler and the frequency doubling source module through a waveguide, the frequency doubling source is connected to the transmitting source through a radio frequency cable, the coupling end of the coupler is connected to the first receiving module through a waveguide, and the first receiving module is connected to the signal distribution module through a radio frequency cable;

[0045] Step 2, the scanning probe is not equipped with a polarization rotator;

[0046] Step 3: The terahertz antenna is installed on the antenna base and its polarization is kept consistent with that of the scanning probe. The antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable to ensure that the rotation axis of the antenna coincides with the azimuth rotation axis of the turntable. The pitch axis of the multi-degree-of-freedom turntable is made to coincide with the pitch axis of the antenna base by adjusting the pitch, up and down, front and back axis systems.

[0047] Step 4, the output end of the antenna to be tested is connected to the low noise amplifier and the second receiving module through a waveguide, and the second receiving module is connected to the signal distribution module through a radio frequency cable;

[0048] Step 5, the reference signal channel and the test signal channel of the signal distribution module are connected to the intermediate frequency receiving port of the vector network analyzer through a radio frequency cable;

[0049] Step 6, calculate and set the scanning range of the scanning probe on the X-axis of the scanning frame according to the radiation pattern confidence angle and the height of the antenna cover, and the scanning step of the X-axis and Y-axis is less than 1 / 2 wavelength; the calculation formula of the scanning range L is: L = 2·h·tanθ+d, where h is the height of the antenna cover, θ is the radiation pattern confidence angle, and d is the lateral size of the probe;

[0050] Control the antenna base so that the test angle is (α, β), move the turntable to -α, and adjust the multi-degree-of-freedom turntable so that the antenna aperture is parallel to the scanning probe aperture;

[0051] Step 7: Use the terahertz antenna to measure the horizontal component electric field E of the test signal. x Conduct data collection;

[0052] Step 8: Install a polarization rotator on the probe to measure the vertical component of the electric field E of the test signal through the terahertz antenna. y Conduct data collection;

[0053] Step 9: Install the radome to be tested on the terahertz antenna and collect the horizontal component electric field E with the radome. x and the vertical component of the electric field E y ;

[0054] Step 10, for both cases of not installing the radome and installing the radome, based on the compensation data and the horizontal component electric field and the vertical component electric field output by the network vector analyzer, a near-far field transformation algorithm is used to obtain the far-field radiation patterns of the antenna and the radome respectively.

[0055] Step 11, obtaining the electrical performance parameters of the radome by comparing the far-field radiation patterns of the antenna and the radome.

[0056] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that he or she may still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents. Such modifications or replacements shall not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and shall be included in the protection scope of the present application.

Claims

1. A near-field test device for electrical properties of a terahertz antenna and a radome, which comprises a vector network analyzer, a multi-degree-of-freedom turntable, a low-noise amplifier, a first receiving module, a second receiving module, a signal distribution module, a local oscillator source, a transmitting source, a switch, a computer and an I / O interface card, a coupler, a two-dimensional scanning frame, a polarization rotator, a scanning probe, a terahertz antenna, and a radome, wherein: A radome to be tested is installed outside the terahertz antenna, and the radome and the antenna are installed together on a multi-degree-of-freedom turntable; the terahertz antenna is connected to a vector network analyzer through a low-noise amplifier, a second receiving module, and a signal distribution module, and a local oscillator source provides a local oscillator signal to the signal distribution module, and the vector network analyzer and the local oscillator source are connected through a BNC cable; a computer is connected to the local oscillator source and the vector network analyzer through a switch, triggers and controls the vector network analyzer and the local oscillator source, and collects data from the vector network analyzer; The two-dimensional scanning frame is arranged in front of the terahertz antenna, and is an inverted T-shaped structure, including an X-axis and a Y-axis; the scanning probe is installed on the Y-axis; when it is necessary to measure the vertical component electric field of the terahertz signal, the polarization rotator is installed on the scanning probe; the scanning probe is connected to the frequency multiplication source module and the first receiving module through a coupler, and the first receiving module is connected to the signal distribution module; the computer is connected to the transmitting source through the I / O interface board, and controls the transmitting source to output the terahertz signal to the scanning probe and the first receiving module through the frequency multiplication source module and the coupler, and the scanning probe transmits the terahertz signal as a test signal and receives it through the terahertz antenna; The signal distribution module multiplies the local oscillator signal provided by the local oscillator source and sends it to the first receiving module and the second receiving module. The first receiving module uses the terahertz signal as a reference signal to mix and down-convert the local oscillator signal to obtain a reference intermediate frequency signal and sends it to the signal distribution module. The signal distribution module amplifies the intermediate frequency signal and sends it to the network vector analyzer. The test signal received by the terahertz antenna is amplified by a low-noise amplifier, mixed and down-converted with the local oscillator signal by the second receiving module, and a test intermediate frequency signal is obtained and sent to the signal distribution module. The signal distribution module amplifies the test intermediate frequency signal and sends it to the network vector analyzer; the network vector analyzer performs coherent processing on the test intermediate frequency signal and the reference intermediate frequency signal to obtain the horizontal component electric field and the vertical component electric field and output them to the computer; When it is necessary to measure the horizontal component electric field of the terahertz signal, there is no need to install a polarization rotator on the scanning probe, and the test signal can be directly transmitted through the scanning probe. When it is necessary to measure the vertical component electric field of the terahertz signal, it is necessary to install a polarization rotator, which is used to rotate the polarization of the test signal emitted by the scanning probe by 90°.

2. According to the near-field test device for electrical properties of terahertz antenna and radome according to claim 1, its feature is that the reference signal is collected by link direct coupling, and the signal path is sequentially a transmitting source, a radio frequency cable, a frequency multiplication source module, a coupler, a first receiving module, a signal distribution module, a vector network analyzer, and a computer.

3. According to the terahertz antenna and radome electrical performance near-field test device as described in claim 1, its feature is that the terahertz antenna is fixed to the antenna base, the antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable, and the rotation axis of the antenna is ensured to coincide with the rotation axis of the azimuth table.

4. The near-field test device for electrical properties of a terahertz antenna and a radome according to claim 1 is characterized in that the pitch axis of the multi-degree-of-freedom turntable coincides with the pitch axis of the antenna by adjusting the pitch, up and down, and front and back positions of the azimuth table.

5. The near-field test device for electrical properties of a terahertz antenna and a radome according to claim 1 is characterized in that the directional pattern compensation data of the scanning probe and the compensation data of the polarization rotator are obtained by theoretical simulation or calibration of the scanning probe, and the far-field directional pattern of the antenna and the radome is obtained by using a near-to-far-field transformation algorithm based on the compensation data and the horizontal component electric field and the vertical component electric field output by a network vector analyzer.

6. The near-field test device for electrical performance of a terahertz antenna and radome according to claim 1 is characterized in that the electrical performance parameters of the radome, including power transmission efficiency, sidelobe level elevation, and beam width change, are obtained by comparing the far-field radiation patterns of the antenna and the radome.

7. A near-field test method for electrical performance of a terahertz antenna and a radome, characterized in that: include: Step 1, the scanning probe is installed on the Y axis of the two-dimensional scanning frame, connected to the coupler and the frequency doubling source module through a waveguide, the frequency doubling source is connected to the transmitting source through a radio frequency cable, the coupling end of the coupler is connected to the first receiving module through a waveguide, and the first receiving module is connected to the signal distribution module through a radio frequency cable; Step 2, the scanning probe is not equipped with a polarization rotator; Step 3: The terahertz antenna is installed on the antenna base and its polarization is kept consistent with that of the scanning probe. The antenna base is fixed to the azimuth table of the multi-degree-of-freedom turntable to ensure that the rotation axis of the antenna coincides with the azimuth rotation axis of the turntable. The pitch axis of the multi-degree-of-freedom turntable is made to coincide with the pitch axis of the antenna base by adjusting the pitch, up and down, and front and back different axis systems. Step 4, the output end of the antenna to be tested is connected to the low noise amplifier and the second receiving module through a waveguide, and the second receiving module is connected to the signal distribution module through a radio frequency cable; Step 5, the reference signal channel and the test signal channel of the signal distribution module are connected to the intermediate frequency receiving port of the vector network analyzer through a radio frequency cable; Step 6, calculate and set the scanning range of the scanning probe on the X-axis of the scanning frame according to the confidence angle of the radiation pattern and the height of the antenna cover; control the antenna base so that the test angle is (α, β), move the turntable azimuth to -α, and adjust the multi-degree-of-freedom turntable so that the antenna aperture is parallel to the scanning probe aperture; Step 7: Use the terahertz antenna to measure the horizontal component electric field E of the test signal. x Conduct data collection; Step 8: Install a polarization rotator on the probe to measure the vertical component of the electric field E of the test signal through the terahertz antenna. y Conduct data collection; Step 9: Install the radome to be tested on the terahertz antenna and collect the horizontal component electric field E with the radome. x and the vertical component of the electric field E y ; Step 10, for both cases where the radome is not installed and where the radome is installed, based on the compensation data and the horizontal component electric field and the vertical component electric field output by the network vector analyzer, the far field patterns of the antenna and the radome are obtained using a near-far field transformation algorithm; The compensation data includes: compensation data of the scanning probe's directional diagram obtained by theoretical simulation or calibration of the scanning probe and compensation data of the polarization rotator; Step 11, obtaining the electrical performance parameters of the radome by comparing the far-field radiation patterns of the antenna and the radome.

8. The near-field testing method for electrical properties of a terahertz antenna and a radome according to claim 7, characterized in that: The scanning step of the X-axis and the Y-axis is less than 1 / 2 of the wavelength of the terahertz wave; wherein the calculation formula of the scanning range L is: L=2·h·tanθ+d, wherein h is the height of the antenna cover, θ is the confidence angle of the radiation pattern, and d is the lateral size of the probe.

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