CN110018361A - A kind of phased array antenna gain-to-noise temperature ratio value measurement method and system - Google Patents

Abstract

A method for measuring the gain-to-noise temperature ratio of a phased array antenna, comprising the following steps: step 1, using a plane near-field measurement system to measure near-field vector data of a phased array antenna to be measured at a certain frequency; step 2, using a signal source, Spectrum analyzer and probe, measure the carrier-to-noise ratio of the center of the mouth of the phased array antenna to be tested at the frequency described in step 1; calibrate the signal power emitted by the probe; step 3, use the carrier-to-noise ratio, signal The power, the gain of the probe, and the near-field vector data described in step 1 are used to calculate the gain-to-noise-temperature ratio of the phased array antenna to be tested. The method of the invention requires less site size, avoids error accumulation, and has high measurement accuracy.

Description

A method and system for measuring the ratio of gain to noise temperature of a phased array antenna

technical field

The invention relates to a phased array antenna gain-noise-temperature ratio measurement method and system, belonging to the antenna near-field measurement technology.

Background technique

In a phased array antenna receiving system, the ratio of the antenna gain to the system noise temperature is usually called the gain-to-noise temperature ratio (referred to as G/T value). The G/T value is used to measure the sensitivity of the receiving system. The higher the G/T value, the stronger the antenna's ability to receive or detect weak signals. Therefore, the G/T value is the key technical index of the phased array antenna system and an important basis for evaluating whether the phased array antenna has completed the given design.

The traditional phased array antenna G/T value measurement methods, according to the measured phased array antenna aperture size and structural characteristics, mainly include indirect measurement and direct measurement.

The indirect measurement method refers to the measurement of the phased array antenna receiving gain and the equivalent noise temperature respectively. The indirect measurement method usually uses the near-field and far-field antenna pattern test system to measure the phased array antenna gain, uses a spectrum analyzer or power meter to measure the phased array antenna equivalent noise temperature, and obtains the phased array antenna G through mathematical operations. /T value. Because the indirect measurement method independently measures the receiving gain and the equivalent noise temperature, the accumulation of errors leads to the low measurement accuracy of the method, and it is rarely used in engineering.

The direct measurement method is usually carried out in the antenna far-field or compact field laboratory. With the aid of the auxiliary illumination signal with known power, the carrier-to-noise ratio of the output signal of the phased array antenna is measured to obtain the antenna G/T value. The direct measurement method does not need to measure the gain and the equivalent noise temperature separately, avoids the accumulation of errors when measuring multiple parameters separately, and has high measurement accuracy. The direct measurement method requires that the measurement quiet zone size of the laboratory is larger than the radiation aperture of the phased array antenna, which is usually difficult for the conventional antenna far-field laboratory to meet the phased array radar antenna with larger aperture, which limits the application scope of the method.

In order to meet the needs of accurate measurement of the G/T value of large-diameter or millimeter-wave phased array antennas, it is necessary to explore new G/T value measurement methods. .

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, a method for measuring the G/T value of a phased array antenna based on an antenna plane near-field pattern measurement system is provided. The microwave instrument realizes the accurate measurement of the G/T value of the phased array antenna in the near field, and meets the measurement and control requirements of the G/T value of the large phased array antenna.

The object of the present invention is achieved through the following technical solutions:

A method for measuring the ratio of gain to noise temperature of a phased array antenna, comprising the following steps:

Step 1. Use a plane near-field measurement system to measure the near-field vector data of the phased array antenna to be measured at a certain frequency;

Step 2, using a signal source, a spectrum analyzer, and a probe to measure the carrier-to-noise ratio of the center of the mouth surface of the phased array antenna to be measured at the frequency described in step 1; calibrating the signal power emitted by the probe;

Step 3: Calculate the gain-to-noise-temperature ratio of the phased array antenna to be measured by using the carrier-to-noise ratio, signal power, and probe gain described in Step 2, and the near-field vector data described in Step 1.

In the above method for measuring the gain-to-noise temperature ratio of the phased array antenna, the gain-to-noise temperature ratio G/T of the phased array antenna to be measured in step 3 is:

In the formula, π is the pi, k is the Boltzmann constant, λ is the wavelength of the electromagnetic wave corresponding to the test frequency, δ _x is the sampling step of the probe in the x-axis direction of the scanning frame of the planar near-field measurement system, and δ _y is the probe in the x-axis direction. The sampling step in the y-axis direction of the gantry of the planar near-field measurement system, is the normalized (x, y) position point on the scanning plane to receive the vector data of the probe, j is the imaginary unit, e is the natural constant, is the projection vector of the wave vector on the scanning plane, is the probe position vector, is the carrier-to-noise ratio, P _in is the signal power transmitted by the probe, and G _P is the gain of the probe.

In the above method for measuring the gain-noise-temperature ratio of phased array antennas, in step 1, the distance between the probe face of the planar near-field measurement system and the face of the phased array antenna to be measured is greater than 3 to 5 times the wavelength of the electromagnetic wave corresponding to the test frequency; The sampling interval of the probe of the planar near-field measurement system is less than or equal to 0.5 times the wavelength of the electromagnetic wave corresponding to the test frequency. The peak level is 30dB lower.

In the above method for measuring the gain-to-noise temperature ratio of phased array antenna, in step 2, when measuring the carrier-to-noise ratio of the center of the aperture of the phased array antenna to be measured at the frequency described in step 1, the signal source outputs a single carrier signal.

In the above method for measuring the gain-noise-temperature ratio of a phased array antenna, in step 2, a power measuring device is used to calibrate the power of the signal emitted by the probe.

A phased array antenna gain-noise-temperature ratio measurement system, comprising a plane near-field measurement subsystem, a spectrum measurement device, and a power measurement device; the plane near-field measurement subsystem at least includes a signal source, a probe, and a test computer;

The planar near-field measurement subsystem is used to measure the near-field vector data of the phased array antenna to be measured at a certain frequency; the signal source is used to output a certain signal to the probe, and the spectrum measurement device is used to measure the to-be-measured phased array antenna. Measuring the carrier-to-noise ratio of the center of the aperture of the phased array antenna under the signal output by the signal source; the power measuring device is used to calibrate the signal power emitted by the probe;

The test computer calculates the gain-to-noise-temperature ratio of the phased array antenna to be tested according to the carrier-to-noise ratio, the signal power, the gain of the probe, and the near-field vector data.

In the above-mentioned phased array antenna gain-to-noise-temperature ratio measurement system, the method for calculating the gain-to-noise temperature ratio G/T of the phased array antenna to be measured by the test computer is as follows:

In the formula, π is the pi, k is the Boltzmann constant, λ is the wavelength of the electromagnetic wave corresponding to the test frequency, δ _x is the sampling step of the probe in the x-axis direction of the scanning frame of the planar near-field measurement subsystem, and δ _y is the probe The sampling step in the y-axis direction of the gantry of the planar near-field measurement subsystem, is the normalized (x, y) position point on the scanning plane to receive the vector data of the probe, j is the imaginary unit, e is the natural constant, is the projection vector of the wave vector on the scanning plane, is the probe position vector, is the carrier-to-noise ratio, P _in is the signal power transmitted by the probe, and G _P is the gain of the probe.

In the above phased array antenna gain-to-noise temperature ratio measurement system, the distance between the probe face of the planar near-field measurement subsystem and the face of the phased array antenna to be measured is greater than 3 to 5 times the wavelength of the electromagnetic wave corresponding to the test frequency; the planar near-field The sampling interval of the probe of the measurement subsystem is less than or equal to 0.5 times the wavelength of the electromagnetic wave corresponding to the test frequency. The peak level is 30dB lower.

In the above phased array antenna gain-noise-temperature ratio measurement system, the signal source is used to output a certain single carrier signal to the probe.

In the above phased array antenna gain-noise-temperature ratio measurement system, the spectrum measurement device is a spectrum analyzer, and the power measurement device is a power meter.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Compared with the direct measurement method of the G/T value in the far field or the compressed field, the present invention adopts the plane near field measurement system to realize the accurate measurement of the G/T value of the phased array antenna, and the method no longer needs to be measured The antenna and the auxiliary measurement antenna meet the far-field distance and have a small requirement for the site size;

(2) Compared with the direct measurement method in the far field or the constricted field, the present invention measures the G/T value of the phased array antenna in the near field of the plane, which can unify the test site with the debugging and correction of the phased array antenna, and avoid the phased array antenna. The phased array antenna is repeatedly turned between laboratories, which shortens the development cycle of the phased array antenna;

(3) Compared with the indirect measurement method of G/T value in the near field of the plane, the present invention uses the near field probe for transmission and the measured phased array antenna for reception. The effective noise temperature is measured uniformly, avoiding the accumulation of errors when the two are measured independently, and the measurement accuracy is high.

Description of drawings

Fig. 1 is the step flow chart of the inventive method;

FIG. 2 is a schematic diagram of the erection of the antenna under test in the near field of the plane according to the embodiment of the present invention;

3 is a block diagram of a typical planar near-field testing system according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a connection between a spectrum analyzer and a signal source according to an embodiment of the present invention;

FIG. 5 is a comparison of G/T value measurement results between the embodiment of the present invention and the far-field direct method.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

A method for measuring the gain-noise-temperature ratio of a phased array antenna, as shown in Figure 1, includes the following steps:

Step 101, using a plane near-field measurement system to measure the near-field vector data of the phased array antenna to be measured at a certain frequency; the distance between the probe of the plane near-field test system and the phased array antenna to be measured, and the sampling interval of the plane near-field probe , the plane near-field probe scanning range and other settings are consistent with the plane near-field pattern measurement standard. That is, the plane near-field pattern measurement standard usually requires that the distance between the probe mouth of the plane near-field measurement system and the mouth of the phased array antenna to be measured is greater than 3 to 5 electromagnetic wave wavelengths corresponding to the test frequency, and the sampling interval of the plane near-field probe is less than or equal to 0.5 times the wavelength of the electromagnetic wave corresponding to the test frequency, the measured level received by the planar near-field probe at the edge of the scanning area is at least 30dB lower than the peak level in the scanning area.

Step 102, using the signal source output signal source to output a single carrier signal to the probe, connecting the spectrum analyzer to the phased array antenna to be measured, and measuring the carrier-to-noise ratio of the center of the mouth of the phased array antenna to be measured at the frequency described in step 1; Use a power meter to calibrate the signal power emitted by the probe.

Step 103: Calculate the gain-to-noise-temperature ratio of the phased array antenna to be measured by using the carrier-to-noise ratio, signal power, and gain of the probe described in step 102, and the near-field vector data described in step 101. The gain-to-noise-temperature ratio G/T of the phased array antenna to be tested is:

In the formula, π is the pi, k is the Boltzmann constant, λ is the wavelength of the electromagnetic wave corresponding to the test frequency, δ _x is the sampling step of the probe in the x-axis direction of the scanning frame of the planar near-field measurement system, and δ _y is the probe in the x-axis direction. The sampling step in the y-axis direction of the gantry of the planar near-field measurement system, is the normalized (x, y) position point on the scanning plane to receive the vector data of the probe, j is the imaginary unit, e is the natural constant, is the projection vector of the wave vector on the scanning plane, is the probe position vector, is the carrier-to-noise ratio, P _in is the signal power transmitted by the probe, and G _P is the gain of the probe.

A phased array antenna gain-noise-temperature ratio measurement system, comprising a plane near-field measurement subsystem, a spectrum measurement device, and a power measurement device; the plane near-field measurement subsystem at least includes a signal source, a probe, and a test computer;

The planar near-field measurement subsystem is used to measure the near-field vector data of the phased array antenna to be measured at a certain frequency; the signal source is used to output a certain signal to the probe, and the spectrum measurement device is used to measure the to-be-measured phased array antenna. Measuring the carrier-to-noise ratio of the center of the aperture of the phased array antenna under the signal output by the signal source; the power measuring device is used to calibrate the signal power emitted by the probe;

The test computer calculates the gain-to-noise-temperature ratio of the phased array antenna to be tested according to the carrier-to-noise ratio, the signal power, the gain of the probe, and the near-field vector data. The calculation method of the gain-to-noise-temperature ratio G/T of the phased array antenna to be tested is:

In the formula, π is the pi, k is the Boltzmann constant, λ is the wavelength of the electromagnetic wave corresponding to the test frequency, δ _x is the sampling step of the probe in the x-axis direction of the scanning frame of the planar near-field measurement subsystem, and δ _y is the probe The sampling step in the y-axis direction of the gantry of the planar near-field measurement subsystem, is the normalized (x, y) position point on the scanning plane to receive the vector data of the probe, j is the imaginary unit, e is the natural constant, is the projection vector of the wave vector on the scanning plane, is the probe position vector, is the carrier-to-noise ratio, P _in is the signal power transmitted by the probe, and G _P is the gain of the probe.

Example:

The basic idea of the G/T value measurement method of the phased array antenna proposed by the present invention can be summarized as follows:

First, the phased array antenna under test is set up in the plane near field laboratory according to the measurement state of the plane near field pattern, and the near field amplitude and phase data of the phased array antenna under test are measured with the help of the plane near field test system;

Next, move the near-field probe to the center of the phased array antenna, disconnect the RF connection cable between the power amplifier unit and the probe of the planar near-field test system, and disconnect the mixing module of the planar near-field test system from the phased array antenna under test. RF connection cable between. Connect the probe to the microwave signal source through the RF cable, and connect the output port of the phased array antenna under test to the spectrum analyzer through the RF cable;

Third, the signal source transmits an auxiliary single-carrier signal, and the carrier-to-noise ratio of the output signal of the phased array antenna under test is tested by the spectrum analyzer, and the power of the single-carrier signal fed into the near-field probe port at this time is calibrated;

Finally, through data calculation, the G/T value of the phased array antenna is obtained.

The steps of the G/T value measurement method in the embodiment of the present invention are as follows:

Step 1: Set up the phased array antenna under test in the plane near-field laboratory according to the requirements of the pattern test, as shown in Figure 2. The plane near-field measurement system uses a near-field probe for transmission, and the phased array antenna under test for reception. Figure 3 is a connection block diagram of a typical plane near-field test system.

Step 2: Rotate the polarization direction of the probe to make the polarization direction of the probe and the antenna under test consistent. The antenna under test is turned on and set to the receiving state.

Step 3: Measure the frequency point f ₀ according to the G/T value, and test the near-field vector data of the corresponding frequency point of the antenna (x, y are the probe sampling positions). The sampling steps of the probe in the x and y directions are δ _x and δ _y respectively. During the test, the distance between the probe and the antenna under test is greater than 3 to 5 electromagnetic wave wavelengths corresponding to the test frequency, and the sampling interval of the plane near-field probe is less than or equal to 0.5 times. For the wavelength of the electromagnetic wave corresponding to the frequency, the measurement level received by the planar near-field probe at the edge of the scanning area is at least 30dB lower than the peak level in the scanning area.

Step 4: Move the near-field probe to the center of the antenna port, and disconnect the test system cable (cable a and cable b in Figure 3) connected to the phased array antenna under test and the near-field probe.

Step 5: Connect the near-field probe to the microwave signal source, and connect the output port of the phased array antenna under test to the spectrum analyzer, as shown in Figure 4.

Step 6: Set the frequency of the signal source to f ₀ , make the signal source output a single-carrier signal, adjust the output power of the signal source, and confirm that the phased array antenna under test works in the linear region. Through the spectrum analyzer, record the carrier-to-noise ratio C/N ₀ of the output signal of the phased array antenna under test.

Step 7: Disconnect the RF cable connected to the near-field probe, and use a power meter to calibrate the signal power Pin at the feed port position of the near-field probe _in step 6 (see Figure 4).

Step 8: Data processing, the measured phased array antenna antenna G/T value is:

In the formula,

G/T, the G/T value of the measured phased array antenna (linear polarization), in dB/K;

k, Boltzmann constant, the value is 1.3806505×10 ^-23 J/K;

λ, the wavelength of the electromagnetic wave corresponding to the test frequency;

The probe at the position corresponding to the center of the antenna port on the scanning plane receives the vector data;

The probe at the position corresponding to the (x, y) position on the scanning plane receives the vector data;

Will relatively Normalized vector data;

δ _x , the sampling step of the probe in the x-axis direction of the scanning gantry of the planar near-field measurement subsystem;

δ _y , the sampling step of the probe in the y-axis direction of the gantry of the planar near-field measurement subsystem;

The projection vector of the wave vector on the scanning plane;

k _x , the wave vector direction component

k _y , wave vector direction component;

probe position vector;

carrier-to-noise ratio;

P _in , the signal power emitted by the probe, in W;

G _P , the gain of the probe.

Figure 5 is a comparison of the G/T value measurement results using the measurement method of the present invention and the far-field direct measurement method. The operating bandwidth of the phased array antenna under test is 100MHz, and a total of 3 frequency points of the center frequency point and the upper and lower side frequencies are selected to perform G/T values respectively. For T value measurement, the maximum difference between the test results of the two methods is less than 0.1dB, and the measurement results of each method are within the error range of the measurement results of the other method.

The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. a kind of phased array antenna gain-to-noise temperature ratio value measurement method, characterized by the following steps:

Step 1: measuring phased array antenna to be measured in the near-field vector data of certain frequency using Planar Near Field Test System；

Step 2: measuring phased array antenna aperture centre to be measured frequency described in step 1 using signal source, frequency spectrograph, probe Carrier-to-noise ratio under rate；The signal power of calibration probe transmitting；

Step 3: using the gain of carrier-to-noise ratio described in step 2, signal power, probe, and, near field described in step 1 Vector data calculates the gain-to-noise temperature ratio value of the phased array antenna to be measured.

2. phased array antenna gain-to-noise temperature ratio value measurement method according to claim 1, it is characterised in that: step 3 Described in phased array antenna to be measured gain-to-noise temperature ratio value G/T are as follows:

In formula, π is pi, and k is Boltzmann constant, and λ is the corresponding electromagnetic wavelength of test frequency, δ_xTo pop one's head in plane The sampling stepping of the scanning support x-axis direction of near-field measurement system, δ_yTo pop one's head in the scanning support y-axis side of Planar Near Field Test System To sampling stepping,Vector data is received for the probe after (x, y) location point normalization on the plane of scanning motion, j is void Number unit, e is natural constant,The projection vector for being wave vector on the plane of scanning motion,For probe positions vector,It makes an uproar to carry Than P_inFor the signal power of probe transmitting, G_PFor the gain of probe.

3. phased array antenna gain-to-noise temperature ratio value measurement method according to claim 1, it is characterised in that: step 1 In, the distance between probe mouth face and phased array antenna mouth to be measured face of Planar Near Field Test System are greater than 3~5 times of test frequencies Corresponding electromagnetic wavelength；It is corresponding that the sampling interval of the probe of Planar Near Field Test System is less than or equal to 0.5 times of test frequency Electromagnetic wavelength, the measurement that the probe of Planar Near Field Test System is arrived in the scanning area marginal reception of Planar Near Field Test System Level is at least 30dB lower than the peak level in scanning area.

4. phased array antenna gain-to-noise temperature ratio value measurement method according to claim 1, it is characterised in that: step 2 In, when measuring carrier-to-noise ratio of the phased array antenna aperture centre to be measured under frequency described in step 1, the signal source output is single Carrier signal.

5. phased array antenna gain-to-noise temperature ratio value measurement method according to claim 1, it is characterised in that: step 2 In, the signal power of probe transmitting is demarcated using power-measuring device.

6. a kind of phased array antenna gain-to-noise temperature ratio value measuring system, it is characterised in that: including Planar Near-Field Measurement subsystem System, spectrum measuring device, power-measuring device；The Planar Near-Field Measurement subsystem includes at least signal source, probe, tester Calculation machine；

The Planar Near-Field Measurement subsystem is for measuring phased array antenna to be measured in the near-field vector data of certain frequency；The letter Number source is used to export a certain signal to the probe, and the spectrum measuring device is used to measure phased array antenna aperture centre to be measured Carrier-to-noise ratio under the signal of signal source output；The power-measuring device is used to demarcate the signal power of probe transmitting；

The measuring and calculation machine calculates described to be measured according to the carrier-to-noise ratio, signal power, the gain of probe, near-field vector data The gain-to-noise temperature ratio value of phased array antenna.

7. a kind of phased array antenna gain-to-noise temperature ratio value measuring system according to claim 6, it is characterised in that: institute State the method that measuring and calculation machine calculates the gain-to-noise temperature ratio value G/T of the phased array antenna to be measured are as follows:

In formula, π is pi, and k is Boltzmann constant, and λ is the corresponding electromagnetic wavelength of test frequency, δ_xTo pop one's head in plane The sampling stepping of the scanning support x-axis direction of near field measurement subsystem, δ_yFor the scanning support y in Planar Near-Field Measurement subsystem that pops one's head in The sampling stepping of axis direction,Vector data, j are received for the probe after (x, y) location point normalization on the plane of scanning motion For imaginary unit, e is natural constant,The projection vector for being wave vector on the plane of scanning motion,For probe positions vector,For Carrier-to-noise ratio, P_inFor the signal power of probe transmitting, G_PFor the gain of probe.

8. a kind of phased array antenna gain-to-noise temperature ratio value measuring system according to claim 6, it is characterised in that: flat The distance between probe mouth face and phased array antenna mouth to be measured face of face near field measurement subsystem are greater than 3~5 times of test frequencies pair The electromagnetic wavelength answered；It is corresponding that the sampling interval of the probe of Planar Near-Field Measurement subsystem is less than or equal to 0.5 times of test frequency Electromagnetic wavelength, what the probe of Planar Near-Field Measurement subsystem was arrived in the scanning area marginal reception of Planar Near-Field Measurement subsystem It is at least 30dB lower than the peak level in scanning area to measure level.

9. a kind of phased array antenna gain-to-noise temperature ratio value measuring system according to claim 6, it is characterised in that: institute Signal source is stated for exporting a certain single-carrier signal to the probe.

10. a kind of phased array antenna gain-to-noise temperature ratio value measuring system according to claim 6, it is characterised in that: The spectrum measuring device is frequency spectrograph, and the power-measuring device is power meter.