Absolute power calibration method for large antenna array

Abstract

A large-scale antenna array absolute power calibration method is characterized in that a standard gain antenna is installed at an unoccupied position of an antenna array surface, a group of electronic switch matrixes are installed between the standard gain antenna and an antenna array radio frequency feed channel, and a tuner for receiving signals is in a form that four loudspeakers are perpendicular to each other. A wide-frequency-band horn antenna covering the working frequency band of the system is additionally arranged at the central position of a tuner of system calibration equipment; the calibration equipment computer gates the wide-band horn antenna by controlling the electronic switch, receives signals radiated to the inherent antenna of the antenna array and the additionally installed standard gain antenna respectively, and analyzes and calculates the absolute power of the system through a comparison method; the method does not need to frequently replace and erect standard antennas to calibrate the absolute power, greatly improves the calibration efficiency of the absolute power of the large antenna array, reduces errors caused by manual replacement of the fixed standard antennas, and effectively improves the test efficiency.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency simulation test systems, and particularly to a method for calibrating the absolute power of a large antenna array. Background Art

[0002] A large antenna array is an important part of a radio frequency simulation test system. Generally, to meet the requirement of simulating a large field of view angle of a device under test, the antenna array of a radio frequency simulation test system generally has characteristics such as a large size and a large number of antenna elements to meet factors such as far-field distance and simulation accuracy. In a radio frequency simulation test system, the antenna array is mainly used to radiate radio frequency signals generated by a signal environment simulation subsystem into a microwave anechoic chamber, and under the control of a semi-physical radio frequency simulation test system control computer, by controlling the amplitude and phase of the radio frequency signals, to simulate the continuous movement of a radar target in azimuth and elevation angles.

[0003] Radio frequency simulation test systems have been widely used in the research and performance testing of fields such as radar and communication. Among them, testing the operating range of detection and guidance devices such as radar and seeker heads is a key performance index for evaluating them. Currently, the absolute power calibration of a large spherical antenna array of a radio frequency simulation system is generally carried out by erecting a standard antenna for measurement. Usually, before conducting an experiment, a high-frequency head needs to be installed on a three-axis simulation turntable at the center of the antenna array spherical surface first, and a system calibration device is used to test the initial value, balance value, and angular simulation accuracy of the radio frequency simulation test system to ensure that the system simulation accuracy meets the experimental requirements. Then, the system calibration device at the center of the antenna array spherical surface needs to be removed, and a standard antenna is erected at this position. To ensure the test accuracy, a narrow-band and high-gain antenna is mostly selected as the standard antenna. According to the characteristics of the standard antenna itself, the antenna sizes in different frequency bands vary greatly. To be fixed on the three-axis simulation turntable, different installation jigs need to be replaced for fixing the standard antenna for different test frequency bands, and the radio frequency cables also need to be reconnected. After the hardware connection is completed, the standard gain horn antenna receives the air-feed signal, and the spectrum analyzer measures the relative amplitude of the signal, and calculates the absolute power density of the signal radiated by the array to the signal received at the center of rotation of the turntable. The process is cumbersome, the test period is long, and at the same time, the human influence factors introduced by connecting the radio frequency cables are also uncontrollable. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a method for calibrating the absolute power of a large antenna array, which does not require frequent replacement and erection of a standard antenna to calibrate the absolute power, greatly improves the calibration efficiency of the absolute power of the large antenna array, reduces the error caused by manually replacing and fixing the standard antenna, and effectively improves the experimental efficiency.

[0005] To achieve the above purpose, the present invention adopts the following technical solution: A method for calibrating the absolute power of a large antenna array,

[0006] Step 1: Install a standard gain antenna and a switch matrix

[0007] According to the operating frequency band of the system, a set of standard gain antennas is equipped. The standard gain antennas are installed at the vacant positions on the antenna array surface. When all the antennas on the antenna array surface in the anechoic chamber are installed and optically adjusted, by adjusting the six-degree-of-freedom device, ensure that the axis center of the radiation beam width of the standard gain antenna is aligned with the center of the high-frequency head of the system calibration device installed on the turntable. The six-degree-of-freedom regulator is used for the mechanical position adjustment of the RF target linear array antenna elements. Each antenna element in the same band must be on a sphere with a corresponding radius to ensure the equal-phase surface on the aperture of each unit antenna, which is adjustable in the rotation direction respectively to ensure the appropriate polarization characteristics of the antenna elements; adjust the front and rear radial directions of each unit antenna to ensure equal distance; adjust the left / right / up / down of each unit antenna to ensure equal distance between the antennas and on the same horizontal line; and adjust the left / right rotation and up / down rotation of each unit antenna by a certain angle to ensure that each antenna element is in the radial direction, and the adjustments between the six degrees of freedom do not interfere with each other. After adjustment and testing, lock it; install a set of electronic switch matrices between the standard gain antenna and the RF feed channel of the antenna array. For the test requirements of different frequency bands, path selection is carried out through the electronic switch matrix, and control switching is carried out between the standard gain antennas of different frequency bands to improve the test efficiency and avoid errors caused by manually adjusting the signal source cable;

[0008] Step 2: Install and test an absolute power antenna at the center of the high-frequency head

[0009] The high-frequency head for receiving signals is in the form of four mutually perpendicular horns. Add a broadband horn antenna covering the operating frequency band of the system at the center position of the high-frequency head of the system calibration device. When testing the absolute power, the calibration device computer selects and gates the broadband horn antenna through the electronic switch to receive the signals radiated by the inherent antenna of the antenna array and the additionally installed standard gain antenna respectively, and analyzes and calculates the system absolute power through the comparison method;

[0010] Step 3: Calibrate the system absolute power

[0011] Use a calibrated signal simulation device to provide the input power P 0 , respectively select the radiation signals of two antennas on the antenna array surface. One is the array surface antenna; the other is the standard gain antenna. According to the test frequency, select the standard gain antenna corresponding to the frequency through the electronic switch; when measuring different frequencies, the signal simulation device sets the corresponding frequency, the electronic switch matrix switches and gates the standard gain antenna of the corresponding frequency band, and use the broadband horn antenna added on the high-frequency head of the calibration device to measure the radiation signal to obtain the test power B 0 ; the electronic switch matrix gates the array surface antenna, and use the broadband horn antenna added on the high-frequency head to measure the radiation signal to obtain the test power B 1; The gain G of the known standard gain antenna at the test frequency point 0 , the array radius R, and the input power P 0 , according to the radar equation, the power density S at the center of the sphere of the standard gain antenna is obtained 0 ;

[0012]

[0013] According to the radiation power B of the standard gain antenna at the center of the sphere 0 , the radiation power B of the array antenna at the center of the sphere 1 , and the radiation power density S of the standard gain antenna at the center of the sphere 0 , when the above powers are all in dB, the absolute power density S of the array antenna radiation at the center of the sphere can be obtained by the comparison method 1 ,

[0014] S 1 = S 0 + (B 1 - B 0 )

[0015] The calibration efficiency of the power density can be effectively improved by the above method.

[0016] Further, the radio frequency feeding channel of the antenna array includes a fine control unit, a coarse control unit, a combiner, and an amplifier; the switch matrix is arranged between the combiner and the amplifier of the radio frequency feeding channel of the antenna array, and includes an SP2T switch and two SP4T switches. The SP2T switch is electrically connected to the combiner and the two SP4T switches respectively, and the SP4T switch is electrically connected to the amplifier.

[0017] The beneficial effects of the present invention are: the present invention does not need to frequently replace and erect a standard antenna to calibrate the absolute power, greatly improves the calibration efficiency of the absolute power of the large antenna array, reduces the error caused by manually replacing the fixed standard antenna, and effectively improves the test efficiency; the parts not detailedly introduced in the present invention are the existing common technologies. Brief Description of the Drawings

[0018] The present invention will be further described below with reference to the drawings:

[0019] Figure 1 is a schematic diagram of the working principle of the center of the sphere measurement;

[0020] Figure 2 is a schematic diagram of the installation position of the switch matrix. Specific Embodiments

[0021] The present invention will be further described in detail below in conjunction with the embodiments and the specific embodiments:

[0022] Embodiment 1

[0023] As shown Figure 1 in the figure, according to the system operating frequency band, a set of standard gain antennas are equipped. The standard gain antennas are installed at the vacant positions on the antenna array surface. When all the antennas on the antenna array surface in the anechoic chamber are installed and optically adjusted, by adjusting the six-degree-of-freedom device, ensure that the radiation beam width axis center of the standard gain antenna is aligned with the center of the high-frequency head of the system calibration equipment installed on the turntable. The six-degree-of-freedom regulator is used for the mechanical position adjustment of the RF target linear array antenna elements. Each antenna element in the same band must be on a sphere with a corresponding radius to ensure the equal-phase surface on the aperture of each unit antenna. The rotation direction is adjustable respectively to ensure the appropriate polarization characteristics of the antenna elements; adjust the front and rear radial directions of each unit antenna to ensure equal distance; adjust the left / right / up / down of each unit antenna to ensure equal distance and equal horizontal line between the antennas; and adjust the left / right rotation and up / down rotation of each unit antenna by a certain angle to ensure that each antenna element is in the radial direction, and the adjustments among the six degrees of freedom do not interfere with each other. After the adjustment and test are completed, lock them; As shown Figure 2 in the figure, a set of electronic switch matrices are installed between the standard gain antenna and the RF feed channel of the antenna array. For the test requirements of different frequency bands, path selection is carried out through the electronic switch matrix, and control switching is carried out between the standard gain antennas of different frequency bands to improve the test efficiency and avoid the errors caused by manually adjusting the signal source cable; The RF feed channel of the antenna array includes a fine control unit, a coarse control unit, a combiner, and an amplifier; The switch matrix is arranged between the combiner and the amplifier of the RF feed channel of the antenna array, and includes an SP2T switch and two SP4T switches. The SP2T switch is electrically connected to the combiner and the two SP4T switches respectively, and the SP4T switch is electrically connected to the amplifier;

[0024] The RF system calibration equipment is used for the calibration of the system angle simulation accuracy. The high-frequency head for receiving signals is in the form of four mutually perpendicular horns. A broadband horn antenna covering the system operating frequency band is added at the center position of the high-frequency head of the system calibration equipment. When testing the absolute power, the calibration equipment computer selects the broadband horn antenna through the control electronic switch, receives the signals radiated by the inherent antenna of the antenna array and the added standard gain antenna respectively, and the system absolute power can be obtained through comparative analysis and calculation;

[0025] Adopt a calibrated signal simulation device to provide the input power P 0 , select the radiation signals of two antennas on the antenna array surface respectively. One is the array surface antenna; the other is the standard gain antenna. According to the test frequency, select the standard gain antenna corresponding to the frequency through the electronic switch; When measuring different frequencies, the signal simulation device sets the corresponding frequency, the electronic switch matrix switches and selects the standard gain antenna of the corresponding frequency band, and uses the broadband horn antenna added on the high-frequency head of the calibration equipment to measure the radiation signal to obtain the test power B 0; The electronic switch matrix gates the planar array antenna, and uses the wide-band horn antenna added to the high-frequency head to measure the radiation signal to obtain the test power B 1 ; The gain G of the known standard gain antenna at the test frequency point 0 , the radius R of the planar array, and the input power P 0 , and according to the radar equation, the power density S at the center of the sphere of the standard gain antenna is obtained 0 ;

[0026]

[0027] According to the radiation power B of the standard gain antenna at the center of the sphere 0 , the radiation power B of the planar array antenna at the center of the sphere 1 and the radiation power density S of the standard gain antenna at the center of the sphere 0 , when the above powers are all in dB, the absolute power density S of the radiation of the planar array antenna at the center of the sphere can be obtained by the comparison method 1 ,

[0028] S 1 =S 0 +(B 1 -B 0 )

[0029] The calibration efficiency of the power density can be effectively improved by the above method

[0030] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention

Claims

1. A method for calibrating absolute power of a large antenna array, characterized by: Step 1: Install standard gain antenna and switch matrix According to the system operating frequency band, a group of standard gain antennas are equipped. The standard gain antennas are installed in the free positions of the antenna array. When all antennas on the array are installed and optically adjusted in the shielded darkroom, the six-degree-of-freedom device is adjusted to ensure that the center of the radiation beam width axis of the standard gain antenna is aligned with the center of the high-frequency head of the system calibration equipment installed on the turntable. The six-degree-of-freedom adjuster is used to adjust the mechanical position of the RF target linear array antenna unit. Each antenna unit of the same band must be on a spherical surface of the corresponding radius to ensure the equiphase plane on the aperture of each unit antenna, which can be adjusted in the rotation direction to ensure the appropriate polarization characteristics of the antenna unit; adjust the front and rear diameters of each unit antenna Direction to ensure equal distance: adjust each unit antenna left / right / up / down to ensure that the antennas are equidistant and on the same horizontal line; and each unit antenna rotates left / right and up / down at a certain adjustment angle to ensure that each antenna unit is in the radial direction, and the adjustments between the six degrees of freedom do not interfere with each other. After the adjustment test is completed, lock it; install a set of electronic switch matrices between the standard gain antenna and the antenna array RF feed channel. According to the test requirements of different frequency bands, the electronic switch matrix is ​​used to select the path, and the control switching is performed between the standard gain antennas of different frequency bands, so as to improve the test efficiency and avoid the error caused by manual adjustment of the signal source cable; Step 2: Install and test the absolute power antenna at the center of the high-frequency head The high-frequency head used to receive signals is in the form of four speakers perpendicular to each other. A wide-band horn antenna covering the system working frequency band is added at the center of the high-frequency head of the system calibration equipment. When testing the absolute power, the calibration equipment computer controls the electronic switch to select the wide-band horn antenna, and receives the signals radiated by the inherent antenna of the antenna array and the additional standard gain antenna. The absolute power of the system can be obtained by comparative analysis and calculation; Step 3: System absolute power calibration A calibrated signal simulation device is used to provide input power P0, and the radiation signals of the two antennas on the antenna array are selected respectively, one of which is the array antenna; the other is the standard gain antenna. According to the test frequency, the standard gain antenna of the corresponding frequency is selected through the electronic switch; when measuring different frequencies, the signal simulation device sets the corresponding frequency, and the electronic switch matrix switches the standard gain antenna of the corresponding frequency band. The wide-band horn antenna added to the high-frequency head of the calibration equipment is used to measure the radiation signal to obtain the test power B0; the electronic switch matrix selects the array antenna, and the wide-band horn antenna added to the high-frequency head is used to measure the radiation signal to obtain the test power B1; Given the gain G0, array radius R, and input power P0 of the standard gain antenna at the test frequency, the power density S0 at the center of the standard gain antenna is obtained according to the radar equation. According to the radiation power B0 of the standard gain antenna at the center of the sphere, the radiation power B1 of the array antenna at the center of the sphere, and the radiation power density S0 of the standard gain antenna at the center of the sphere, when the above powers are all in dB, the absolute power density S1 of the array antenna at the center of the sphere can be obtained by comparison method. S1=S0+(B1-B0) The above method can effectively improve the efficiency of power density calibration.

2. A large-scale antenna array absolute power calibration method according to claim 1, characterized in that: The antenna array RF feed channel includes a fine control unit, a coarse control unit, a combiner, and an amplifier; the switch matrix is ​​arranged between the combiner and the amplifier of the antenna array RF feed channel, including an SP2T switch and two SP4T switches, the SP2T switch is electrically connected to the combiner and the two SP4T switches respectively, and the SP4T switch is electrically connected to the amplifier.

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