Some standard content:
Standard of the Ministry of Electronics Industry of the People's Republic of China Antenna Test Methods
Special Measurement Methods
This standard includes some special methods for measuring antenna characteristics. 1 Simulation method
1.1 Main uses of simulation method
1.1.1 Special working environment
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Sometimes it is impossible to measure antennas in the actual working environment. In this case, proportional simulation method is often used. For example, this situation often occurs when antennas are installed on large supporting structures such as ships, aircraft and large artificial satellites (which have an impact on antenna performance). In a moving system or a changing environment, the instability of the supporting vehicle or the surrounding medium makes the experimental data have unreasonable components, which requires statistical processing.
1.1.2 Development stage
During the development stage, the plan needs to be constantly modified. Because the final antenna system is too large or too small, the simulation method is often used. In this way, the main advantage of the simulation is that there is more room for adjustment during the measurement process, or money can be saved during the experiment. 1.2 Conditions that must be met when using models for simulation
Usually, the model is a prototype antenna that is reduced in size, but whether it is reduced or enlarged, strict simulation with models must meet the following requirements.
1.2.1 The size of the model should be times that of the prototype antenna. 1.2.2 The operating frequency and the conductivity used in the model should be n times that of the prototype antenna. 1.2.3 The dielectric constant and permeability of the material used in the model should be the same at the proportional frequency as at the original frequency. 1.2.4 Notes
The above n is an arbitrary number that determines the scale of the model (usually greater than 1, but not necessarily so). The imaginary parts of the complex dielectric constant and complex permeability mentioned above are included in the expression of conductivity. Occasionally, a more general form of the proportional model is required that allows some additional parameters to be changed. 1.3 Limitations of simulation methods
1.3.1 Inaccuracies in material simulation
It is generally impossible to strictly meet all the requirements listed above in a practical model. However, for antennas that are not highly resonant, the errors are usually small if good conductors are simulated by good conductors such as copper or aluminum, and low-loss dielectrics are simulated by low-loss dielectrics with the same dielectric constant and permeability. The main difficulty arises in the case of poor conductors or lossy dielectrics, where materials that meet the requirements of scale models may not always be available.
1.3.2 Inaccuracies in environmental simulation
When constructing a scale model, it is necessary to construct not only the antenna to be simulated, but also those parts of the surrounding components and environment that have a significant impact on the antenna's characteristics. In many cases, it is difficult to construct a simulated environment because the electromagnetic environment is very complex. For example, when the antenna interacts with the ground, it is usually impractical to accurately simulate the changing and sometimes unknown soil properties. In these cases, simplified models can be used, and it is necessary to make a correct judgment as to how much of the antenna's surrounding environment should be simulated. For example, if the VHF antenna is located near the cockpit, the cockpit interior must be simulated quite accurately. On the other hand, if the grid antenna is installed at the tail, the cockpit part does not need to be simulated so accurately.
1.3.2.1 Simplification of the environment
1985-01-05 Issued by the Ministry of Electronics Industry of the People's Republic of China 1
1986-07-01 Implementation
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It is often necessary to try to test the scale model of the antenna alone without the constraints of its environment in order to determine whether it has the same electrical characteristics as the prototype antenna. To accomplish this test, a simplified environment can be constructed, such as a flat circular ground plane (usually a current rejection ring is added along the edge of the simulated circular ground plane to prevent current from being excited on the back of the simulated surface) in order to measure the significant characteristics of the prototype antenna (such as the radiation pattern). Then determine the scale of the simplified environment and the antenna. If the results obtained using a scale model of the antenna adequately reproduce the results of the prototype antenna, then the scale model can be used in a scale model of the antenna environment.
1.4 Simulation Methods for Multiple Antennas
When measuring input impedance and pattern using a scale model, if the prototype antenna is in a system that contains multiple antennas, all adjacent antennas should be included in the model and terminated with appropriate impedances. Since other antennas may operate at different frequencies than the antenna being simulated, the impedance at the operating frequency should be correctly simulated. To obtain this data, the matching section can be terminated in a network equivalent to the impedance measured on the scale model. 1.5 Simulation of Electrically Small Antennas
Similar to the method for the low-frequency case, special measurements of electrically small antennas are often made using an electrostatic cage in a quasi-static manner. The equivalent area can be determined by measuring the charge induced by a known field strength. 1.6 Rigorous Scale Models
Although the antenna characteristic of most interest in model measurements is usually the radiation pattern, other antenna characteristics of interest can also be reliably reproduced. If the exact ratio method described above is followed throughout the antenna system, all field structures will be exactly reproduced both externally and in the feeder. Thus power gain, directivity, radiation efficiency, input impedance, mutual impedance, aiming errors, in short all characteristics which depend only on the ratio of the fields will be preserved.
1.7 Modified Scaled Model
If the modified ratio method is followed, the efficiency cannot be reproduced. Consequently, the power gain cannot be reproduced, but the remaining characteristics can still be reproduced accurately enough for most purposes, provided that the antenna has no excessive current, charge concentration or mismatch. 1.8 Antenna Characteristics That Cannot Be Measured with Scaled Models Certain antenna characteristics, such as the power level of the high voltage breakdown and the noise temperature characteristics, cannot be measured with scaled models because of the frequency-dependent mechanisms involved.
1.9 Effect of Cables in Scaled Model Measurements
When measuring the radiation pattern, the feeder cable has a significant effect on the quantity being measured. In this case, the scaled model antenna can be fed with a battery-powered transmitter. On the other hand, the scale model antenna may include a receiver, and the demodulated signal is extracted from the receiver by a high-impedance conductor, which can minimize the interference of the cable with the RF field. Another approach is to use a semiconductor laser and transmit the signal by an optical fiber. 1.10 Influence of the support structure
If the null structure of the directional pattern is to be accurately determined, special attention should be paid to the support structure of the model. 1.11 Other issues
In addition to the special issues of scale model measurements covered in this standard, there are some general procedures and precautions that can be adopted in any measurement (see SJ2534.6-85 "Antenna Test Methods Antenna Test Field Operation"). 2 Antenna Focusing Method
2.1 Overview
In some cases, it is difficult or impractical to measure antenna characteristics using the far-field test method. The antenna focusing method is to focus the antenna under test at the distance to be measured, so that the far-field directional pattern of the antenna can be measured at this shortened distance. 2.2 Antennas suitable for focusing method measurements
This method is limited to antennas that have a device to change their focus from infinity to a finite distance. This transformation is usually achieved using phased array antennas or reflector antennas. 2.3 Application of focusing method to parabolic antennas A lot of research work has been done on this aspect using parabolic reflector antennas, because this antenna is the most commonly used large antenna. 2
2.3.1 Principle of focusing method
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Figure 1 Geometric relationship of focusing by geometric optics method
Figure 1 shows the ray optics geometric relationship used to establish parabolic focusing. When the feed antenna is located at point F, the antenna is focused at infinity. When the feed is moved to position F, the rays are focused at the quasi-focus F\. F\ is not a true focus because the reflector shape is a parabola rather than a circular surface. Only an elliptical surface has two foci at finite distances. 2.3.2 Distance of feed movement
The distance that the feed should move can be determined by ray tracing method, and its approximate expression is: +(D)
Where: R
=distance OFW
=focal length;
=distance FF!
(see Figure 1). After the feed is moved to point F, the antenna radiation pattern can be measured at distance R, and the feed returns to its original position F after the measurement.
2.3.3 Limitations of the method
When the distance is shortened to D?/8, the measurement results can still accurately depict the main lobe of the far-field pattern of the antenna focused at infinity, but the measured side lobes have errors. 2.3.4 Local improvements to the method
Finely adjusting the position of the feed near point F can improve the method to a certain extent. Method 2.3.4.1
Adjust the position of the feed source so that the first null of the antenna pattern is the deepest, which can provide a better depiction of the main lobe. However, if the power gain of the focused antenna is measured at a distance R, the result will be a few tenths of a decibel lower than the far-field measurement. 2.8.4.2 Method 2
Adjust the feed position so that the power gain in the direction of the main lobe peak of the focused antenna under test measured at a distance R is the largest. When measuring power gain, the result obtained by this method is slightly better than the result obtained by the criterion of the deepest first zero point. 2.3.5 Application of the method
Although this method has some disadvantages, it has been proven to be very effective. 38 Near-field detection method using mathematical transformation
3.1 Overview
The near-field detection method using mathematical transformation is another near-field method for determining antenna characteristics. 3.1.1 Measurement process
The main process of completing this measurement is as follows. 3.1.1.1 Sample the complex vector field (amplitude and phase) on a completely determined surface. 3
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8.1.1.2 The measured data are processed by a computer to obtain the angular spectrum distribution of the plane wave, cylindrical wave or spherical wave suitable for the measurement surface used.
8.1.1.3 Taking into account the influence of the directivity and polarization of the measurement detector, the angular spectrum distribution is corrected (called detector correction technology). 3.1.1.4 Based on the corrected angular spectrum distribution, the far-field parameters such as power gain, relative radiation pattern and polarization are calculated. 8.1.2 Basic principles
3.1.2.1 Field expansion
Theoretical analysis shows that the field of the antenna under test can be expressed as a selection of basic fields, which are the solutions of Maxwell's equations on the surface used. For a plane, the basic field is a plane wave represented by a complex exponential function, for a cylinder, the basic field is a cylindrical wave represented by a Bessel function and a complex exponential function, and for a sphere, the basic field is a spherical wave represented by a joint Legendre function and a spherical Bessel function. 8.1.2.2 Field Fitting
Fit the complex vector receiving pattern of the detector to the corresponding basic function, that is, the response function of the detector represented by the same basic field. At this point, the output voltage of the detector when it moves along the surface can be represented by the known detector response, the basic field function of the antenna under test, and the effect of the orientation and movement of the detector. 3.2 Planar Near Field Method
In the planar near field method, the amplitude and phase of the electric field components on a plane in front of the antenna under test are measured. Through this example, the above ideas and some concepts related to measurement methods and calculations can be deeply understood. A lot of research has been done on the planar near field method, and the concepts related to cylindrical and spherical surfaces can be regarded as a generalization of this well-known situation. 3.2.1 Basic formula
3.2.1.1 Complex signal at the output of the detector If the xy position of the detector on the z=d plane is represented by user, the complex signal at the output of the detector is: V(P)=ao JJso.(k).tor(k)eydJeit.dk d, . In the formula:
xy part of the wave vector: =k+k,, where,,, is the unit vector o(K)-the transmission characteristic of the antenna under test: y=±kz$
factor. And e is the result of the detector movement; (2)
. () The far-field response of the detector is a complex vector function. For each value, it gives the response of the antenna to the plane wave incident from that direction.
. The size of each component of () is the same as the far-field radiation pattern of the detector, so it can be determined based on the ordinary radiation pattern measurement (amplitude and phase). ().
8.2.1.2 Transformation of complex signals
Transforming V(P) yields an equation for the two components of ro(K): So(K).to(R)=-e)d
-JJV(P)eP d.dy ...
4-element-ag
Repeating the above measurements with a second "independent" detector yields the required second equation, which can be obtained by rotating the linearly polarized detector 90° around its axis.
8.2.1.8 Far-field parameters
Using the two equations obtained in 3.2.1.2, the two components of () can be determined, and the far-field parameters are obtained by (). For example, the power gain is:
Where: ", the reflection coefficient of the antenna.
G() =4(/k)2[,(K) 2
(4)
3.2.2 Test Equipment
The main components of this measurement system are shown schematically in Figure 2. The scanner is a large mechanical structure similar to an x-recorder. It 4
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supports the detector and moves it on a plane for measurement. Optional Inputs for the Clamp
Digital Position
Display Axis BCD
(Scanner)
Positioner
Vertical Synchronization
Digital Position BCD
Horizontal Synchronization
Display Axis
Positioner Motor Control
Stepper (\or)
Positioner Motor Machine control
Scanning (I or Y)
Digital position
Programmer
Position command
Optional coupler
Positioner
Control unit
Richness digital
Converter
BCD output
Digital data
Coupler
BCD output
Phase digital
Converter
Figure 2 Block diagram of automatic positioning and measurement system 3.2.2.1 Accuracy of detector planar motion
Recordant
Reference signal
Amplitude and phase
Phase sensitive interface
To white detection||tt ||the signal of the detector
The scanner must be precisely manufactured to maintain the accuracy of the detector plane motion xλ/100 and accurately know the xy position of the detector.
3.2.2.2 Scanning area
Data measurements should be made at points equally spaced in the x and directions, and the scanning area should be slightly larger than the antenna area. The size of this area basically determines the maximum angle at which the far-field data can be accurately calculated. The relationship is: tan-
Where: ax-
-the antenna size in the x direction,
-the scanning length.
3.2.2.3 Sampling spacing
(5)
The spacing between data points should be slightly smaller than 1λ/2. For wide beam antennas , the spacing may be as small as λ/4, while for highly directional antennas the spacing may be increased to about one wavelength. To determine the optimum spacing and scan area and to verify that multiple reflections are indeed negligibly small, experiments should be performed on actual antenna-detector pairs. 8.2.3 Computational Methods
The main computational effort is to integrate to find S. (K). (). This integral is a complex two-dimensional Fourier transform, and the fast Fourier transform (FFT) is very efficient for this integral. 3.2.4 Limitations of the Planar Near-Field Method
The planar near-field method has been used for a variety of antennas over a frequency range from about 1 GHz to 65 GHz. The effectiveness of the absorbing material and the beamwidth of the antenna limit the low frequencies, while the accuracy of the positioner limits the high frequencies. The planar near-field method works well for directional antennas, and the error is greatest near ± 90° from the normal to the measurement plane. If the energy is large over a wide angle, an excessively large scan area may be required, in which case cylindrical or spherical scanning is more effective.
3.8 Cylindrical near-field method
In the case of a cylindrical scanning surface, the theory and calculations are more complicated than in the case of a plane. The main calculations can still be done with FFT, and the influence of the detector directivity must still be compensated. The cylindrical scanning surface is obtained by the one-dimensional motion of the detector plus the rotation of the antenna under test on the azimuth positioner. This reduces the complexity of the scanner, but increases the amount of microwave absorbing material required. 6
3.4 Spherical near-field method
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When using a spherical scanning surface, the mathematical problem is much more complicated. Although FFT can still be used for most calculations, there is still a considerable amount of work to obtain far-field parameters from the measured data. Only for some ideal or simple detectors can a complete detector correction be obtained. In principle, this scanning surface is most suitable for wide-beam antennas. "Free scanning" can be obtained by mounting the antenna under test on a two-axis positioner and keeping the detector fixed. This method can be used to obtain the scanning surface for large antennas already installed on the locator without adding any hardware. 4 Medium-distance antenna testing technology
4.1 Overview
4.1.1 Basic principles
The medium-distance testing technology uses a distance between 2D2/input and the near-field distance. The amplitude and phase are tested at the medium distance, and then the "medium to far field" transformation is performed in some way to obtain the far-field radiation pattern. 4.1.2 Main Advantages
One obvious advantage of this technique is that the traditional far-field test site can be adapted to medium-distance testing. The test tower, locator and other equipment at a distance are retained, and the existing test site can be modified by adding new receiving and recording systems to make measurements using this method. This is more advantageous than building a separate near-field device, because most antenna tests are best performed using conventional methods, while far-field test sites may still require use.
4.2 Test Method
4.2.1 Holographic Technology
4.2.1.1 Equipment Block Diagram
Antenna under test
Grid scanning
Remote control antenna
Attenuation core port
Phase shifter
National reference antenna
Hybrid joint T
Output data
Figure 3 Holographic Technology
Signal rating
The equipment used in the holographic technology is shown in Figure 3. A fixed microwave horn generates a reference wave, which is combined with the antenna signal through a T-shaped hybrid.
4.2.1.2 Measurement and data processing
The hologram is obtained by scanning the antenna in the form of a grid determined by the positioner axis using the antenna's pitch-azimuth positioning system. The data matrix formed from the regular sampling of the holographic signal is quickly transformed by the computer to obtain various antenna diagrams. 4.2.1.3 Features
a. A feature of this "pure" holographic technique is that only an amplitude receiver (rather than an amplitude-phase receiver) is required, because the phase information is stored in the holographic process. b. It is easy to transform from the test data to the aperture area, thereby obtaining the surface error of the antenna. 4.2.2 Interference technique
4.2.2.1 The device block diagram is shown in Figure 4. In the figure, A is the antenna under test, placed on a two-axis positioner, B is the fixed reference antenna, and C is the distant antenna. The figure shows the test equipment in an echo-free room. The system is the same for indoor or outdoor test sites. Figure 5 shows the feeding circuit, including phase shifters that can shift 90° and 180° from an arbitrary reference zero point. 6
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Figure 4 Test system structure
4.2.2.2 Test
RF signal source
Distribution
Phase shifter
Matching load
Figure 5 Feeding of antennas A and B
The antenna under test and the reference antenna are basically fed in parallel to obtain the interference pattern. As with holographic technology, the interference pattern essentially contains phase information. The data sampling of the antenna under test needs to be done with a two-axis positioner. The cutting method can be great circle cutting or conical cutting. 5 Sweep frequency method
5.1 The main purpose of the sweep frequency method
5.1.1 Determine the frequency of "anomalies" in broadband antennas When measuring the radiation pattern of very broadband antennas, such as log-periodic antennas, at discrete frequencies within the operating frequency band, important changes in their amplitude radiation pattern may be missed. These changes are generally frequency-dependent and narrow-band. This phenomenon is often called "anomalies" in the radiation pattern. Eliminating the "anomalies" can usually optimize the design of these antennas. The frequency sweep method can be used to determine the frequency of "anomalies".
5.1.2 Measurement of cross-polarization in the far field of antennas
The sweep frequency method is particularly suitable for measuring cross-polarization in the far field of antennas. The reason is that complex mechanical support components will produce cross-polarization. Various electrical resonances exist in these components, resulting in scattered radiation whose amplitude varies sharply with frequency. Note that if the components are large in terms of wavelengths, the relevant frequency range will not be very wide. Subsequently, the gain variation with frequency is measured. 5.2 Cutting and recording method
5.2.1 Cutting method
Usually, only the main plane cutting is required. For linearly polarized antennas, only the E-plane and H-plane cutting can be performed. During measurement, one spatial angular coordinate of the antenna under test is fixed, while the other angular coordinate changes incrementally within the angular range of interest. 5.2.2 Recording method
For each angular increment, when the operating frequency is scanned within the operating frequency band of the antenna under test, the amplitude of the received signal is continuously recorded. All curves are recorded on the same sheet of paper to obtain a family of curves. If the gain and amplitude radiation patterns of the antenna under test are idealized, that is, they do not change with frequency, then from the Friis transmission formula, it can be seen that the family of curves measured on the logarithmic-frequency scale should be composed of a family of approximately parallel straight lines with a slope of -6dB per octave. In order to obtain such a result, the antenna test field and its test equipment must be ideal. 5.3 Requirements for test equipment and data correction method 5.3.1 Requirements for test equipment
If the measurement is carried out in a good free space test field, in order to obtain good results, an optimal broadband source antenna and a receiving system with a nearly flat frequency response should be selected for this test field. The curve shown in Figure 6 is a typical result. If the measurement is carried out in a conical echo-free chamber, it is necessary to ensure that the source antenna is sufficiently close to the top of the chamber so that there are no deep valleys in the irradiated field. Therefore, it is a good idea to use the frequency sweep method to verify the position of the source antenna.
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Frequency (GHz)
Figure 6 Amplitude radiation pattern of a broadband antenna as a function of frequency with an angular coordinate step of 5° (the longest line is the side-fire case) 5.3.2 Data correction
Frequency-dependent reflections and the lack of flatness in the frequency response of the test equipment are the main error sources. 5.3.2.1 Method 1
If the responses of the test equipment are known, the data can be corrected based on their responses. 5.3.2.2 Method 2
This method is basically a swept-frequency gain transfer measurement. Use a reference antenna to make a single swept-frequency measurement and store the data. Then use an electronic instrument to compare all the data obtained from the antenna under test with the response of the reference antenna. What is recorded is the difference between the response of the reference antenna and the response of the antenna under test. A data normalizer or an online small computer can be used to complete this task. For any given frequency in the frequency band, the relationship between the relative level and angle at each angular increment is plotted as a curve, which is the amplitude radiation pattern of the antenna under test. 5.3.2.3 Requirements for the reference antenna
The reference antenna should have an amplitude radiation pattern similar to that of the antenna under test, so that the response of the reference antenna to reflections in the test field is roughly the same as that of the antenna under test. In this way, when using method 5.3.2.2, the influence of reflections tends to be eliminated. Obviously, when the antenna under test is turned away from the aiming direction, the error caused by reflection increases. It is also possible to use the antenna under test itself as a reference antenna, in which case the first curve is a straight line. 6 Indirect measurement of antenna characteristics
6.1 Overview
The performance of a reflector antenna depends mainly on the accuracy of its construction. Therefore, the actual surface of the reflector can be measured and the electrical performance of the antenna can be calculated based on these data. In addition, this method can be used as a judgment tool to adjust the reflector surface to within the allowable tolerance range. It is usually desired that the measurement accuracy is at least 1/20 of the shortest operating wavelength.6.2 Measurement method
6.2.1 Decomposition photography triangulation method
6.2.1.1 Decomposition photography
This method uses two or more long-focal-length cameras to reselectively photograph the surface to be measured. The surface to be measured is evenly spread with self-adhesive photographic targets, and the image is presented on photographic paper, as shown in Figure 7. 8
High light position
Focal length (F)
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Photographic coordinate system
Image of target
Camera axis
Used coordinate system
Figure 7 Schematic diagram of decomposed phototriangulation method 6.2.1.2 Data processing
The least squares triangulation processing method is used. According to this method, the two-dimensional measurement results of the target image are processed simultaneously to obtain a unique set of three-dimensional coordinates for each discrete target. 6.2.1.3 Measurement accuracy
The measurement accuracy depends on the degree of measurement method, which can generally reach one 20,000th to one 100,000th of the reflector diameter. 6.2.2 Precision distance measurement method
6.2.2.1 Overview
For large reflector antennas operating at millimeter waves, photogrammetry may not be accurate enough to predict antenna characteristics. Another method that can be used is precision distance measurement. As an example of the accuracy required for this distance measurement method, a 65m antenna operating at a wavelength of 3.5mm is required to be adjusted to an accuracy of ±0.1mm at more than 3000 points. This accuracy can be achieved using the distance measurement method, in which the distance of each point from two fixed points such as the focus and vertex of a parabola is determined. 6.2.2.2 Measurement Methods
When measuring the 65 m antenna mentioned above, the distance measurements of points at distances from a few meters to about 60 m should be completed quickly, preferably using an automatic system. For this purpose, a modulated laser beam can be used. The reflector surface is scattered with a target (a small optical cube) in a manner similar to Figure 7. The laser beam is directed to the target through a programmable mirror. The entire measurement process is controlled by a small digital computer. The phase of the echo signal is measured relative to a reference signal. The phase shift is proportional to the total round trip distance. 6.2.2.3 Method of Resolving Ambiguities
If the distance and modulation frequency cause the phase shift to exceed one period, ambiguities will appear. The ambiguities can be resolved by known rough distances or by using a dual-frequency system.
6.2.2.4 Measurement Accuracy
Using this method, an accuracy of 0.08 mm has been achieved at distances up to 60 m. This method has been used very successfully for large reflector antennas.
6.2.3 Cart measurement method
6.2,3.1 Measurement principle
For high-precision reflector surfaces, the curvature at a certain point on the surface can be measured very accurately using a cart device. The cart contacts the surface to be measured at three points. There is a precision depth sensor (with an accuracy of up to 0.10μm) at its center facing the point to be measured, and rollers are installed at the three contact points. This method can be illustrated with reference to Figure 8. The surface curvature K is: 9
Where: The angle between the tangent line at point P and the x-axis is
one arc length.
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Figure 8 The geometric relationship angle used to relate the coordinates of a point on the reflector surface to the measured curvature can be obtained by integration, that is,
Since sin6, is the derivative of the y coordinate with respect to arc s, then sind.
Therefore, the coordinates of each point on the curve can be obtained by obtaining two integrals. 6.2.8.2 Measurement accuracy bzxZ.net
Since the three contact points of the trolley are equipped with wheels, the trolley can roll along the different radii of the reflector to continuously sample the curvature. This method has achieved an accuracy of 0.05mm. 6.2.3.3 Advantages and disadvantages of the method
Although this method cannot directly give the reading of each independent point, the measurement is fast and convenient. It is sensitive to the roughness and dust of the reflecting surface, but it is very accurate in a short range. If the measurement range is relatively long, the system error tends to accumulate due to the double integration. It is difficult to establish two integral constants from the starting position at the same time. In addition, there are problems such as local false curvature and discontinuity between panels caused by the weight of the trolley. 6.2.4 Other measurement methods
Other indirect measurement methods include the pentaprism method, the steel belt theodolite method, etc. 6.3 Disadvantages of indirect measurement methods
The focus of indirect measurement is to adjust the antenna as accurately as possible, but moving the antenna or changes in ambient temperature and the weight of the antenna may cause it to deform. This can point out which corrections should be made and propose methods to improve the performance of the antenna. Additional remarks:
This standard was proposed by the Standardization Research Institute of the Ministry of Electronics Industry. This standard was drafted by the 39th Institute of the Ministry of Electronics Industry. The main drafters of this standard are Ke Shuren and Wang Shuhui. 10
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