This standard applies to the on-site measurement of amplitude patterns. SJ 2534.7-1986 Antenna test method Field measurement of amplitude patterns SJ2534.7-1986 Standard download decompression password: www.bzxz.net
This standard applies to the on-site measurement of amplitude patterns.

Standard SJ2534.7-86 of the Ministry of Electronics Industry of the People's Republic of China
Antenna test method
Field measurement of amplitude pattern
Published on January 24, 1986
Implemented on October 1, 1986
Ministry of Electronics Industry of the People's Republic of China
Standard Antenna Test Method of the Ministry of Electronics Industry of the People's Republic of China
Field measurement of amplitude pattern
This standard applies to the field measurement of amplitude pattern. 1 Occasions for field measurement
Field measurement must be carried out in the following situations: a. The radiation pattern of the antenna is seriously affected by the installation site; b. The antenna can only be assembled and (or) installed on site; c. Confirm that the performance of the antenna and the interaction between the antenna and the surrounding environment are consistent with expectations. 2 Field measurement methods
SJ2534.7-86
Field measurements of antenna radiation patterns are generally divided into two types, namely, measurement methods using moving sources and measurement methods using stationary sources. This standard does not consider the specialized techniques required for each field antenna measurement method. 2.1 Types of sources
The source must be located in the far area of ​​the antenna system being measured, which can be divided into artificial sources and extraterrestrial radio sources. 2.1.1 Artificial sources
The tools for carrying artificial sources include:
a, various air vehicles: such as ordinary airplanes, helicopters, small airships, and free and tethered balloons: b, artificial earth satellites, including orbital satellites and synchronous satellites. 2.1.2 Extraterrestrial radio sources
These include the sun, the moon, and cosmic radio sources. 2.2 Measuring patterns using moving sources
2.2.1 Typical measurement system
The typical measurement system is shown in Figure 1. The distant source is carried by a vehicle that flies through the space surrounding the antenna under test. The waves incident on the antenna under test in all directions of interest are essentially plane waves. The direction of the source relative to the reference direction of the antenna under test is obtained by the tracking equipment. This information provides angle data for the recording device, and the amplitude of the signal received by the antenna provides amplitude data for the recorder. Processing these data can give the antenna radiation pattern in the required form. 2.2.2 Methods for keeping the received signal constant If the attitude of the source antenna changes relative to the antenna under test, the received signal may change. This possibility should be minimized. There are two ways to reduce signal changes. 2.2.2.1 Direct the source antenna
During the measurement, make the beam peak of the source antenna point to the antenna under test, and the useful part of the source antenna radiation pattern should be as uniform as possible.
Promulgated by the Ministry of Electronic Industry on January 24, 1986
Implemented on October 1, 1986
SJ2534.7-86
Possible reference antenna
Measured antennabZxz.net
To recorder
Source antenna
Broadband tracking device
To recorder
Figure 1 System for field measurement of amplitude pattern 2.2.2.2 Selection of favorable flight route
When the source antenna cannot change its beam pointing, the aircraft flight route should be selected to minimize its attitude change. A more favorable route is a circle whose circumference lies in a plane perpendicular to the vertical axis of the antenna and whose center is the intersection of the vertical axis of the antenna and the plane.
2.2.3 Type of source antenna
The design and installation of the source antenna should include the influence of its environment, which depends largely on the relative size of the aircraft and the operating wavelength. Source antennas can be divided into two categories according to this distinction. 2.2.3.1 Source Antennas for HF and VHF Bands In the HF and VHF bands, the choice of source antenna depends on the polarization. a. For horizontal polarization, a sleeve dipole cable towed behind the aircraft can be used. This antenna is composed of a standard coaxial cable with a quarter-wave shielding braid removed, and it can be held in the horizontal position by a small parachute. b. For vertical polarization, a monopole can be used with the aircraft as the "ground plane". Because its radiation pattern is zero in the vertical direction, the influence of the inherent variation of the pattern should be considered when using the source antenna near the zenith of the antenna under test. c. When the polarization must be changed during the measurement, a rotatable ferrite-loaded dipole that can be mounted on the side of the aircraft can be used. Since the aircraft structure is asymmetric with respect to the antenna, careful calibration is required. 2.2.3.2 Source Antennas for Microwave Bands
In the microwave band, a wingtip antenna can be used. Placing the antenna in this position can minimize the influence of the aircraft structure and make the source antenna pattern quite close to the pattern of the isolated source antenna. 2.2.4 Tracking equipment
2.2.4.1 Functions of tracking equipment
The tracking equipment has two functions. First, determine the relative direction of the source antenna. Specifically, to measure the direction of the aircraft relative to the tracking equipment, the direction of the aircraft relative to the measured antenna can be determined by taking into account the parallax caused by the known distance between the measured antenna and the tracking equipment. Second, determine the distance of the source. The distance data is used to calculate the parallax correction and to correct the change in the incident power flux density caused by the aircraft not flying along a circle centered on the measured antenna. 2.2.4.2 Two commonly used tracking equipment
SJ2534.7-86
There are two commonly used tracking equipment, namely optical tracking equipment and radar tracking equipment. The important difference between the two is that ordinary optical tracking equipment can only provide the direction of the source, while radar tracking equipment can provide the direction and distance of the source. Laser tracking equipment can also provide distance. When optical tracking equipment is used, the distance to the source can be calculated from the aircraft position data, which is measured by the test equipment in the aircraft and sent back to the test site. 2.2.5 Reference Antenna
For general field measurements of amplitude patterns, the above system is sufficient. However, when it is necessary to improve the measurement accuracy or to measure other radiation characteristics of the antenna, a reference antenna must be placed near the antenna under test. 2.2.5.1 Role of the Reference Antenna
It should be noted that unless the reference antenna system is carefully designed, it will introduce errors as large as the errors you want to eliminate. For example, in addition to changes in the source, the signal received by the reference antenna may also change due to site reflections. The reference antenna has the following three roles.
2.2.5.1.1 Measuring the apparent change in the source signal strength The amplitude or polarization of the wave radiated by the source to the antenna under test is not stable enough, especially at microwave frequencies. In this case, the reference antenna can be used to measure the apparent change in the source signal strength. This data can be used to normalize the signal received by the antenna under test, and the apparent change in the source signal strength can be eliminated.
2.2.5.1.2 Determine the gain of the antenna under test
Use the reference antenna as the gain standard and use the power gain comparison method to measure the power gain of the antenna under test (see SJ2534.1086 "Measurement of power gain and directivity"). 2.2.5.1.3 Determine the polarization of the antenna under test
The method is to use the reference antenna to measure the polarization of a set of sources, and at the same time measure the polarization of the antenna under test (see SJ2534.9-85 "Polarization measurement").
2.2.5.2 Requirements for the reference antenna
2.2.5.2.1 Basic requirements for design and installation Regardless of the frequency, the basic requirement for the design and installation of the reference antenna system is that its influence on the radiation pattern of the antenna under test can be ignored.
2.2.5.2.2 Requirements for the radiation pattern
At microwave frequencies, it is hoped that the response of the reference antenna is basically independent of the ground and surrounding structures. In order to meet this requirement, a reference antenna with a narrow beam and low sidelobe should be used, and the ground and other components near the reference antenna need to be analyzed. At frequencies far below the microwave band, the reference antenna's directional pattern may be very wide, so ground reflections cause significant changes in the received reference signal. If the directional pattern of the reference antenna system can be accurately determined, its output can still be used to correct the changes in the source signal strength when measuring the directional pattern of the antenna under test. 2.2.6 Measurement and recording methods
The measurement and recording method of the directional pattern can be point-by-point or continuous, the latter being better. Continuous recording equipment should preferably be able to automatically make various corrections when inputting signals and angles. Data can also be sampled, stored and processed by a computer. Antenna directional patterns have various representations, the most comprehensive of which is the equipotential line diagram (see SJ2534.3-84 "Measuring radiation patterns in antenna test fields"). 2.2.7 Interferometer method
SJ 2534.7-86
The radio measurement method of the power pattern of the antenna has been widely used. Its main disadvantage is the small dynamic range. The interferometer method developed on the basis of this method basically overcomes this disadvantage. 2.2.7.1 Typical measurement system
The basic block diagram of the interferometer method is shown in Figure 2. The antenna under test and the auxiliary antenna are connected through a correlation receiver to form an interferometer. The output signal of the interferometer is related to the correlation voltage on the two antennas. 2.2.7.2 Measurement method
The auxiliary antenna always points to the source at the speed of the earth's rotation, and the antenna under test is fixed to the orbit of the radio source. Due to the relative motion of the antenna under test to the source, the output signal of the interferometer will change in proportion to the radiation pattern of the antenna under test. Auxiliary antenna
Mixer
Amplifier
Oscillator
Correlator
Test antenna
Energizer
Amplifier
Figure 2 Basic block diagram of interferometer
2.2.7.3 Requirements for the angular size of the source
In order to give full play to the advantages of this method, the angular size of the source must be smaller than the spacing of the interference fringes. Since the angular size of all the strongest sources is a few arc minutes, the application of this method is limited. 2.3 Measurement of the radiation pattern using a stationary source
Transmitter
Receiver
Recorder
Feed source system mirror
Measurement antenna
Figure 3 Block diagram of satellite measurement
Working station
SJ 2534.7-86
This method uses the onboard antenna on a synchronous satellite as a source and is generally used to measure the radiation direction of the antenna of a satellite communication ground station. 2.3.1 Typical measurement system
The block diagram of the measurement system is shown in Figure 3. The measurement of the antenna radiation pattern is carried out via the satellite and the cooperating ground stations (telemetry, tracking, command and listening stations). 2.3.2 Measurement method
2.3.2.1 Measurement of the radiation pattern on the receiving frequency The cooperating station transmits a fixed, unmodulated transmission carrier to the satellite. The antenna under test moves relative to the satellite and receives the satellite's downlink signal, and the directional pattern can be drawn on the recorder. 2.3.2.2 Measurement of directional pattern at the transmission frequency The antenna under test moves relative to the satellite and transmits an unmodulated transmission carrier to the satellite. The cooperative station receives the satellite downlink signal and records the directional pattern of the antenna under test with a recorder. 2.3.2.3 Measurement of directional pattern of frequency reuse antenna In the case of frequency reuse, the satellite antenna is a high-purity dual-polarization antenna, and the satellite transmits and receives signals in left-hand and right-hand polarization respectively. The difference in measurement method from 2.3.2.1 and 2.3.2.2 is that at the receiving frequency, the antenna under test receives the satellite downlink signal at the same time with two orthogonal ports, and at the transmitting frequency, the antenna under test transmits an unmodulated carrier to the satellite at the same time with two orthogonal ports.
2.3.2.4 Measurement of directional pattern using satellite beacon frequency In some cases, the directional pattern of the ground station antenna (or other antenna) can also be measured using the satellite's beacon signal. Since the beacon signal is weak and the dynamic range of measurement is large, a receiving system with a very narrow frequency band is usually used (such as an equivalent filter with a bandwidth of 10Hz). At this time, in order to eliminate the influence of the beacon carrier frequency drift during the measurement period, the receiving system should be scanned within a sufficiently wide frequency band to ensure that the beacon signal passes periodically within the filter bandwidth. The disadvantage of this method is that it can only measure the directional pattern at the beacon frequency.
Additional Notes
This standard was jointly proposed by the Standardization Research Institute of the Ministry of Electronics Industry and the 39th Institute. This standard was drafted by the 39th Institute of the Ministry of Electronics Industry. The main drafter of this standard
Ke Shuren
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