Antenna radiation efficiency test method based on noise injection balanced receiving system

Abstract

The application is based on the antenna radiation efficiency testing method of the noise injection balanced receiving system: the normalized power pattern in the whole space solid angle of the antenna is tested; the calibration signal inside the noise injection receiver is obtained according to the balanced mode of the noise injection receiver; the antenna is connected to the input end of the noise injection balanced receiving system, the mouth surface calibration source is placed on the antenna, the temperature of the mouth surface calibration source is set, the corresponding noise injection duration is output by the processing collector, the antenna output signal is obtained by using the balanced mode of the noise injection balanced receiving system and the calibration signal; the ideal output signal of the antenna without the influence of the radiation efficiency is calculated by using the antenna power pattern, the temperature signal of the mouth surface calibration source and the darkroom temperature; the relationship between the antenna output signal obtained by the noise injection balanced receiving system and the ideal output signal of the antenna without the influence of the radiation efficiency is established, and the radiation efficiency of the antenna is calculated.

Description

Technical Field

[0001] This invention relates to a method for testing the antenna radiation efficiency of a noise-injected balanced receiving system, belonging to the field of space microwave remote sensing technology. Background Technology

[0002] Traditional solid-aperture radiometers have a small number of antenna elements. In spaceborne applications, the entire radiometer calibration process can be completed by feeding external radiation sources and observing cold space from the antenna end face. To achieve high-resolution and wide-swath observations simultaneously, limitations imposed by mechanical rotation, sensitivity, and resolution mean that solid-aperture scanning radiometers can currently only achieve a 7m antenna aperture. However, further increasing the antenna size would present even greater engineering challenges and is difficult to implement. Synthetic aperture radiometers and digital beamforming pushbroom radiometers represent new radiometer systems. They use multiple small-aperture antenna elements arranged in an array to achieve high-resolution Earth observations. They do not require mechanical scanning, can acquire a wide field of view in a single imaging operation, and are easily expandable. This represents the future development direction for high-resolution and even ultra-high-resolution microwave radiometers.

[0003] For a radiometer system composed of multiple small-aperture antennas, it is difficult to achieve periodic two-point calibration of the antenna aperture after on-orbit operation. It is necessary to use the calibration results of the receiving link at the antenna back end, combined with the antenna's radiation efficiency, to derive the calibration results from the antenna output end to the antenna aperture. Therefore, the accuracy of the antenna radiation efficiency directly affects the measurement accuracy of the entire radiometer system.

[0004] To improve the measurement accuracy of a new type of radiometer system composed of multiple small-aperture antenna arrays, high-precision measurement of antenna radiation efficiency is required, based on which absolute calibration of the entire radiometer system can be completed. Currently, the main method for measuring antenna radiation efficiency is to integrate the electric field on a closed spherical surface in the far-field region of the antenna to obtain the antenna's radiated power or directivity. Given the input power or gain, the antenna radiation efficiency can be calculated. However, this method has low measurement accuracy. Besides reflections from the antenna feed end and absorbing materials, it is also affected by various error sources in the microwave anechoic chamber system, and the measurement accuracy cannot meet the high-precision testing requirements of the radiometer system. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an antenna radiation efficiency testing method based on a noise injection balanced receiving system, thereby improving the testing accuracy of antenna radiation efficiency. This enables the calibration results to be derived to the antenna aperture in the application of a new type of radiometer system composed of multiple small-aperture antennas in an array, thus completing the full-link calibration of the radiometer system.

[0006] The technical solution provided by this invention is: an antenna radiation efficiency testing method based on a noise-injected balanced receiving system, wherein the noise-injected balanced receiving system controls the internal calibration signal T′. N The injection duration makes the externally input noise signal T A With internal calibration signal T′ N To achieve equilibrium, the method involves the following steps:

[0007] S1. Measure the normalized power pattern F(θ,φ) within the solid angle of the entire space of the antenna, where θ is the elevation angle and φ is the azimuth angle. The value of θ ranges from 0 to 180° and the value of φ ranges from 0 to 360°.

[0008] S2. Based on the balanced mode operating principle of the noise-injected balanced receiver system, obtain the calibration signal T′ inside the noise-injected balanced receiver system. N ;

[0009] S3. Connect the antenna to the input of the noise injection balanced receiver system, place the aperture calibration source on the antenna, set the aperture calibration source temperature to TC1, and have the acquisition processor output the corresponding noise injection duration τ. C1 Based on the balanced mode working principle and step S2 of the noise injection balanced receiver system, the calibration signal T′ inside the noise injection balanced receiver system is obtained. N Obtain the antenna output signal T A1 ;

[0010] S4. Utilize the antenna power pattern obtained in step S1 By combining the temperature signal TC1 from the aperture calibration source and the ambient temperature TP0, calculate the ideal output signal T when the antenna is unaffected by radiation efficiency. ideal_1 ;

[0011] S5. Establish the antenna output signal T obtained by the noise injection balanced receiving system in step S3. A1 And the ideal antenna output signal T when there is no radiation efficiency in step S4 ideal_1 The relationship between these factors is used to calculate the antenna's radiation efficiency.

[0012] Preferably, the above-mentioned antenna radiation efficiency testing method based on a noise injection balanced receiving system further includes the following steps:

[0013] S6. Set the temperature signals of the surface calibration source to TC2, TC3, ... TC l …TC L Repeat steps S2-S5 to obtain the radiation efficiency of the antenna when observing different temperature signals from the calibration source at the observation surface. The radiation efficiency of the antenna is obtained by averaging the results of multiple observations, where l = 1 to L, and L is the number of temperature signals.

[0014] Preferably, the specific steps of step S2 are as follows:

[0015] Connect the input of the noise-injected balanced receiver system to a coaxial calibration source. The coaxial calibration source outputs M noise signals TS1, TS2, ..., TS. M Obtain the noise injection durations τ1, τ2, ... τ when the noise injection balanced receiver system reaches balanced mode. M ;

[0016] Based on the noise signals TS1, TS2, ... TS output by the coaxial calibration source M The physical temperature T of the noise injection balanced receiver system pU The coupling factor F of the internal coupler in a noise-injected balanced receiver system NC The noise injection durations τ1, τ2, ..., τ1 of the acquisition processor when the coaxial calibration source outputs the m-th noise signal. M Solve for the calibration signal T′ when the noise-injected balanced receiver system receives M noise signals from the coaxial calibration source. Nm m = 1 to M;

[0017] The scaling signal T′ for M noise signals Nm After averaging, the internal scaling signal T′ of the noise-injected balanced receiver system is obtained. N .

[0018] Preferably, the noise injection balanced receiving system receives the calibration signal T′ when it receives the m-th noise signal from the coaxial calibration source. Nm The calculation formula is:

[0019]

[0020] Preferably, in step S3, the antenna output signal T A1 for:

[0021]

[0022] Among them, T pU The physical temperature F is used to inject noise into a balanced receiving system. NC The coupling factor is used to inject noise into the internal coupler of the balanced receiving system.

[0023] Preferably, the ideal output signal T ideal_1 for:

[0024]

[0025] Preferably, steps S2 to S4 are performed in a microwave anechoic chamber, and the ambient temperature refers to the anechoic chamber temperature.

[0026] Preferably, the noise signal is a brightness temperature signal with a value range of 80K-320K.

[0027] Preferably, the temperature change rate of the coaxial calibration source is less than 5s, and the output brightness temperature accuracy is better than 0.1K.

[0028] Preferably, the aperture calibration source can radiate a variable brightness temperature signal of 80K-320K, with an emissivity better than 0.9999 and a brightness temperature accuracy better than 0.1K.

[0029] The advantages of this invention compared to the prior art are:

[0030] (1) Based on the balanced mode of the noise injection receiver, the present invention establishes a noise injection balanced receiving system and uses the balanced mode to complete the high-precision test of the input signal of the noise injection balanced receiving system.

[0031] (2) The present invention utilizes a coaxial calibration source to provide a high-precision noise signal as the input of the noise injection balanced receiving system, obtains the calibration signal inside the noise injection balanced receiving system according to the balanced mode of the noise injection balanced receiving system, and further improves the test accuracy by averaging the calibration signal through the input of multiple noise signals.

[0032] (3) The present invention builds a test system in a microwave anechoic chamber, shields interference signals and uses a simple temperature measuring device to provide temperature information, so as to establish the ideal output signal when the antenna is not affected by radiation efficiency.

[0033] (4) This invention uses a coaxial calibration source to obtain the calibration signal of the noise-injected balanced receiving system, and then combines it with an aperture calibration source to complete the test of the antenna output signal. By comparing the theoretical output signal of the antenna with the measured output signal of the antenna, the high-precision test of the antenna radiation efficiency is completed. Attached Figure Description

[0034] Figure 1 Block diagram of antenna radiation efficiency testing principle in this invention embodiment;

[0035] Figure 2 Block diagram illustrating the principle of the coaxial calibration source in this invention;

[0036] Figure 3 Block diagram illustrating the principle of the aperture calibration source in this invention;

[0037] Figure 4 A schematic diagram of the test of the noise injection balanced receiving system according to an embodiment of the present invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] Traditional real-aperture radiometers have a small number of antenna elements. In spaceborne applications, two-point calibration of the entire radiometer chain can be completed by feeding an external radiation source and observing cold space from the antenna end face. However, for radiometer systems composed of multiple small-aperture antennas, it is difficult to achieve periodic two-point calibration of the antenna aperture after on-orbit operation. It is necessary to use the calibration results from the receiving link at the antenna end, combined with the antenna's radiation efficiency, to derive the calibration results from the antenna output to the antenna aperture. Therefore, the accuracy of the antenna radiation efficiency directly affects the measurement accuracy of the entire radiometer system chain.

[0040] To improve the measurement accuracy of a new radiometer system composed of multiple small-aperture antenna arrays, high-precision measurement of antenna radiation efficiency is required, followed by absolute calibration of the entire radiometer system. For example... Figure 1 As shown, a test system is formed in a microwave anechoic chamber by connecting the antenna of the device under test (DUT) with a noise injection receiver and a data acquisition processor. The noise injection receiver and data acquisition processor constitute a noise injection balanced receiving system. High-precision known signals are output using a coaxial calibration source and an aperture calibration source. The antenna output signal can be measured by combining the balanced mode of the noise injection balanced receiving system. The received signal under ideal conditions of the antenna is established by using the antenna power pattern and the temperature of the microwave anechoic chamber. The radiation efficiency of the antenna is obtained by relating the ideal received signal of the antenna to the measured output signal of the antenna.

[0041] The coaxial calibration source emits a standard brightness temperature signal through its coaxial port. This signal can vary between 80K and 320K, with a temperature change rate of less than 5 seconds and an output brightness temperature accuracy better than 0.1K. The principle block diagram of the coaxial calibration source is shown below. Figure 2 As shown, a metal thin film cathode load is used, which is immersed in liquid nitrogen to maintain a constant gas pressure inside the noise source Dewar, thereby keeping the boiling point of liquid nitrogen stable. The load temperature and its equivalent noise temperature are accurately defined by the liquid nitrogen temperature.

[0042] The aperture calibration source can radiate a variable brightness temperature signal from 80K to 320K, with an emissivity better than 0.9999 and a brightness temperature accuracy better than 0.1K. The principle block diagram of the aperture calibration source is shown below. Figure 3 As shown, the surface calibration source includes a radiator, a temperature control system (primary temperature control, secondary temperature control, heat transfer network, heating film), a temperature control device (proportional-integral microwave control system, temperature sensor and other peripheral units), a temperature measuring device (thermometer, temperature sensor), and other parts (shell, shielding cover, etc.).

[0043] Noise injection balanced receiver system, such as Figure 4 As shown, the noise-injected balanced receiver system controls the internal calibration signal T′ N The injection duration makes the externally input noise signal T A With internal calibration signal T′N Reach balance. Balance means that the signal T at the input end of the noise injection balanced receiving system A and the calibration signal T' N accumulate equal energy within a preset period of time.

[0044] Among them, the signal T at the input end of the noise injection balanced receiving system A and the calibration signal T' N After being combined through a coupler, the output signal Among them, T' N is the signal after the calibration signal generated by the diode noise source passes through the attenuator and switch 1. The control signal of switch 1 is generated by the acquisition processor and is used to control whether the calibration signal of the diode noise source is connected to the coupler; the coupler output signal After passing through switch 2, it is input to the receiving channel. The control signal of switch 2 is generated by the acquisition processor and is used to control the input signal of the subsequent receiving channel to switch to port 1 or port 2 of switch 2. The receiving channel amplifies, filters, down-converts and filters the input signal and then outputs the intermediate frequency signal IF. The center signal IF enters the acquisition processor.

[0045] The acquisition processor digitally quantifies the sampled signal through AD and then enters the FPGA. Among them, there are multiplier-accumulators, decision modules, switch 1 control signal generation modules and switch 2 control signal generation modules inside the FPGA. The switch 2 on control signal generation module generates a square wave signal with a period of T S , and a duty cycle of 50%: During the low level of the control signal, control switch 2 to switch to port 2. At this time, the receiving channel inputs the matching load signal, and the sampled data of AD enters the multiplier-accumulator a. The multiplier-accumulator a multiplies and accumulates the sampled data and then outputs the result as A; during the high level of the control signal, control switch 2 to switch to port 1. At this time, the input signal of the receiving channel is The sampled data of AD enters the multiplier-accumulator b. The multiplier-accumulator b multiplies and accumulates the sampled data and then outputs the result as B. After one TS cycle ends, the two multiplier-accumulation results A and B enter the decision module, and the decision module judges the sizes of A and B. At the same time, the switch 1 control signal generation module generates a switch 1 control signal according to the result of the decision module. During the high level, switch 1 switches to port 1. At this time, the T' N signal is coupled to the coupler through the coupler and then enters the receiving channel; during the low level, switch 1 switches to port 2. At this time, only the signal TA at the input end of the noise injection balanced receiving system enters the receiving channel. When A > B in the decision module, the switch 1 control signal generation module controls to increase the duration τ of the high level, thereby increasing the size of B; when A < B in the decision module, the switch 1 control signal generation module controls to reduce the duration of τ, thereby reducing the size of B; and so on in a cycle until A and B reach balance.

[0046] This invention provides a method for testing the antenna radiation efficiency of a noise-injection balanced receiving system, the specific steps of which are as follows:

[0047] S1. At the antenna test site, the normalized power pattern F(θ,φ) within the solid angle of the entire space of the antenna is measured, where θ is the elevation angle and φ is the azimuth angle. The value of θ ranges from 0 to 180° and the value of φ ranges from 0 to 360°.

[0048] The preferred solution is as follows:

[0049] At the antenna test site, the geometric center of the antenna is placed on the center target point specified by the robotic arm of the antenna test site (provided by the measurement site). By controlling the motor to scan and rotate and move the robotic arm of the antenna test site, the radio frequency transmission signal of the test site (provided by the measurement site) is located at different positions of the antenna, covering the full solid angle of the antenna θ = 0~180° and φ = 0~360°, so that the radio frequency signal of the antenna in the full solid angle can be obtained. The amplitude of the radio frequency signal received by the antenna is divided by the amplitude of the radio frequency transmission signal of the antenna test site (provided by the measurement site) to obtain the normalized power pattern F(θ,φ) of the antenna, θ = 0~180°, φ = 0~360°.

[0050] S2. Based on the balanced mode operating principle of the noise-injected balanced receiver system, obtain the calibration signal T′ inside the noise-injected balanced receiver system. N ;

[0051] The preferred solution is as follows:

[0052] Antenna radiation efficiency test block diagram is as follows Figure 1 As shown, the test system was built in a microwave anechoic chamber to avoid interference signals affecting the test accuracy. A coaxial calibration source was connected to the input of the noise injection receiver, and the coaxial calibration source output M noise signals TS1, TS2, ... TS1. m …TS M Obtain the noise injection durations τ1, τ2, ... τ when the noise injection balanced receiver system reaches balanced mode. M Considering the coupling factor F of the internal coupler in a noise-injected balanced receiver system. NC When the coaxial calibration source outputs the m-th noise signal TS m The balanced mode of the time-noise-injected balanced receiver system is shown in equation (1):

[0053]

[0054] In the formula, T pU The physical temperature of the noise-injected balanced receiving system, which is also equivalent to the temperature of the noise-matching load, is measured in real time by a temperature measuring device; τm The noise injection duration T′ is the noise injection duration output by the acquisition processor when the m-th noise signal is output from the coaxial calibration source. Nm For a noise-injected balanced receiver system receiving the m-th noise signal from a coaxial calibration source; F NC The coupling factor is used to inject noise into the internal coupler of the balanced receiving system.

[0055] Based on the noise signals TS1, TS2, ... TS output by the coaxial calibration source M The physical temperature T of the noise injection balanced receiver system pU The coupling factor F of the internal coupler in a noise-injected balanced receiver system NC The noise injection durations τ1, τ2, ..., τ1, τ2, ..., τ3 when the coaxial calibration source outputs the m-th noise signal are acquired by the processor. M Solve for the calibration signal T′ of the noise-injected balanced receiver system when it receives M noise signals from the coaxial calibration source. Nm m = 1 to M, where M is greater than or equal to 16.

[0056] Equation (1) can be used to obtain the internal calibration signal T′ when the noise-injected balanced receiving system receives the m-th noise signal from the coaxial calibration source. Nm As shown in equation (2):

[0057]

[0058] The coaxial calibration source outputs M noise signals TS1, TS2, ... TS respectively. m …TS M The acquisition processor outputs the corresponding noise injection durations τ1, τ2, ... τ m …τ M By processing with equations (1) and (2), M noise-injected balanced receiver system calibration signals (T′) can be obtained. N1 ,T′ N2 …,T′ Nm ,…,T′ NM For the scaling signal T′ corresponding to M noise signals, Nm Averaging can improve the measurement accuracy of the calibration signal in a noise-injected balanced receiver system, as shown in equation (3).

[0059]

[0060] This invention utilizes a high-precision known noise signal output from a coaxial calibration source as the input to a noise injection receiver, and uses the balanced mode of the noise injection balanced receiver system to obtain the calibration signal inside the noise injection balanced receiver system.

[0061] The characteristics of noise signals with different amplitudes can be quickly adjusted by using a coaxial calibration source. The internal calibration signals of the noise-injected balanced receiving system under different input conditions can be obtained. By averaging the calibration signals measured under multiple input conditions, the measurement accuracy of the calibration signal can be further improved, and the influence of uncertainties in the testing process can be eliminated.

[0062] S3. Connect an antenna to the input of the noise injection balanced receiver system, place the aperture calibration source on the antenna, set the aperture calibration source temperature to TC1, and have the acquisition processor output the corresponding noise injection duration τ. C1 Based on the balanced mode working principle of the noise-injected balanced receiver system and the calibration signal T′ obtained in step S2 N The antenna output signal T can be obtained. A1 ;

[0063] The preferred solution is as follows:

[0064] Antenna radiation efficiency test block diagram is as follows Figure 1 As shown, the antenna of the device under test is connected to the input terminal of the noise injection receiver. Simultaneously, an aperture calibration source is placed on the antenna aperture. After the aperture calibration source temperature is set to TC1 and reaches a stable temperature, when the balanced mode is achieved using the noise injection balanced receiver system, the acquisition processor outputs the corresponding noise injection duration τ. C1 Combined with the calibration signal T′ obtained in step S2 N The antenna output signal T is calculated using equation (4). A1 :

[0065]

[0066] When placing the aperture calibration source and the antenna aperture, keep them close together so that the aperture calibration source can completely cover the antenna aperture.

[0067] S4. Utilize the antenna power pattern obtained in step S1 By combining the temperature signal TC1 from the aperture calibration source and the ambient temperature TP0, calculate the ideal output signal T when the antenna is unaffected by radiation efficiency. ideal ;

[0068] The preferred solution is as follows:

[0069] When the antenna is unaffected by radiation efficiency, the ideal output signal T is obtained when the antenna observation aperture calibration source TC1 is used. ideal_1 The sum of the received signals from the positive lobe and the back lobe of the antenna is given. The positive lobe corresponds to the range (θ = 0–90°, φ = 0–360°), and the back lobe corresponds to the range (θ = 91–180°, φ = 0–360°). The ideal output signal T is given. ideal_1 As shown in equation (5):

[0070]

[0071] In the formula, the ambient temperature TP0 is obtained by the temperature measuring device.

[0072] Steps S2-S4 utilize a test system built in a microwave anechoic chamber, where the ambient temperature is the anechoic chamber temperature. Interference signals are shielded, and the ideal output signal modeling is less affected by external interference and has high accuracy when the antenna's radiation efficiency is unaffected.

[0073] S5. Establish the antenna output signal T obtained by the noise injection balanced receiving system in step S3. A1 And the ideal antenna output signal T when there is no radiation efficiency in step S4 ideal_1 The relationship between these factors is used to calculate the antenna's radiation efficiency.

[0074] The preferred solution is as follows:

[0075] The antenna output signal T acquired by the noise-injected balanced receiving system A1 And the ideal output signal T of the antenna when there is no radiation efficiency ideal The relationship between them is shown in equation (6):

[0076] T ideal_1 ·η+(1-η)·TP A =T A1 (6)

[0077] The antenna radiation efficiency η1 of the observation aperture calibration source TC1 can be obtained by solving equation (6), as shown in equation (7):

[0078]

[0079] S6. Set the temperature signals of the surface calibration source to TC2, TC3, ... TC l …TC L By repeating steps S2-S5, the radiation efficiency of the antenna when observing different temperature signals from the calibration source at the observation surface can be obtained, and the radiation efficiency of the antenna can be obtained by averaging the results of multiple observations.

[0080] The preferred solution is as follows:

[0081] Set the temperature signals of the surface calibration source to TC2, TC3, ... TC l …TC L By repeating steps S2-S5, the corresponding radiation efficiencies η1, η2...η can be obtained when the antenna observes different temperature signals from the aperture calibration source. l …η L The radiation efficiency η of the antenna is obtained by averaging the results of L observations, as shown in equation (8).

[0082]

[0083] By using multiple radiation efficiency results obtained under different temperature signal output conditions from the antenna observation aperture calibration source, and averaging these multiple radiation efficiencies, the measurement accuracy of antenna radiation efficiency is improved.

[0084] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for testing the antenna radiation efficiency of a noise-injected balanced receiving system, wherein the noise-injected balanced receiving system controls an internal calibration signal. The injection duration makes the externally input noise signal T A With internal calibration signal To achieve equilibrium, its characteristic is The steps are as follows: S1. Measure the normalized power pattern of the antenna across the entire solid angle. , The pitch angle, It is the azimuth angle. The range of values ​​is , The range of values ​​is ; S2. Based on the balanced mode operating principle of the noise-injected balanced receiver system, obtain the calibration signal inside the noise-injected balanced receiver system. ; S3. Connect the antenna to the input of the noise injection balanced receiver system, place the aperture calibration source on the antenna, set the aperture calibration source temperature to TC1, and have the acquisition processor output the corresponding noise injection duration τ. C1 Based on the balanced mode working principle and step S2 of the noise injection balanced receiver system, the calibration signal inside the noise injection balanced receiver system is obtained. Obtain the antenna output signal T A1 ; S4. Utilize the antenna power pattern obtained in step S1 By combining the temperature signal TC1 from the aperture calibration source and the ambient temperature TP0, the ideal output signal when the antenna is unaffected by radiation efficiency is calculated. ; S5. Establish the antenna output signal T obtained by the noise injection balanced receiving system in step S3. A1 And the ideal antenna output signal when there is no radiation efficiency in step S4 The relationship between these factors is used to calculate the antenna's radiation efficiency. Antenna output signal T A1 And the ideal antenna output signal when there is no radiation efficiency in step S4 The relationship between them is: in, The radiation efficiency of the antenna; Antenna radiation efficiency when observing the calibration source TC1 for: S6. Set the temperature signals of the surface calibration source to TC2, TC3, ... TC l …TC L Repeat steps S2-S5 to obtain the radiation efficiency of the antenna when observing different temperature signals from the calibration source at the observation aperture. The radiation efficiency of the antenna is then obtained by averaging the results of multiple observations. , Number of temperature signals; The specific steps of step S2 are as follows: Connect the input of the noise-injected balanced receiver system to a coaxial calibration source. The coaxial calibration source outputs M noise signals TS1, TS2, ..., TS. M Obtain the noise injection durations τ1, τ2, ... τ when the noise injection balanced receiver system reaches balanced mode. M ; Based on the noise signals TS1, TS2, ... TS output by the coaxial calibration source M Physical temperature of noise injection balanced receiver system Coupling factor of the internal coupler in a noise-injected balanced receiver system The noise injection durations τ1, τ2, ..., τ1 of the acquisition processor when the coaxial calibration source outputs the m-th noise signal. M Solve for the calibration signal when the noise-injected balanced receiver system receives M noise signals from the coaxial calibration source. , ; The scaling signal corresponding to M noise signals Averaging is performed to obtain the internal calibration signal of the noise-injected balanced receiver system. .

2. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... The noise injection balanced receiving system receives the coaxial calibration source. The calibration signal when there is a noise signal The calculation formula is: 。 3. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... In step S3, the antenna output signal T A1 for: in, The physical temperature of the balanced receiving system is used to inject noise. The coupling factor is used to inject noise into the internal coupler of the balanced receiving system.

4. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... The ideal output signal for: 。 5. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... Steps S2 to S4 are performed in a microwave anechoic chamber, and the ambient temperature refers to the anechoic chamber temperature.

6. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... The noise signal is a brightness temperature signal, with a value range of 80K~320K.

7. The antenna radiation efficiency testing method based on a noise-injection balanced receiving system according to claim 1, characterized in that... The coaxial calibration source has a temperature change rate of less than 5 seconds and an output brightness temperature accuracy better than 0.1K.

8. The method for testing the antenna radiation efficiency of a noise-injection balanced receiving system according to claim 1, characterized in that... The aperture calibration source can radiate a variable brightness temperature signal of 80K~320K, with an emissivity better than 0.9999 and a brightness temperature accuracy better than 0.1K.

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