This standard applies to the safety limits and protection of electromagnetic radiation. SJ 2534.13-1987 Antenna test method Hazards of electromagnetic radiation SJ2534.13-1987 Standard download decompression password: www.bzxz.net
This standard applies to the safety limits and protection of electromagnetic radiation.

Standard of the Ministry of Electronics Industry of the People's Republic of China Antenna Test Method
Hazards of Electromagnetic Radiation
This standard applies to the safety limits and protection of electromagnetic radiation 1 Overview
1.1 Hazards of Electromagnetic Radiation
SJ2534.13-87
Electromagnetic radiation is a non-ionizing radiation. The spectrum of non-ionizing radiation covers the frequency range up to the ultraviolet region. This radiation is a kind of radiation energy that causes heat by interacting with human tissue (equivalent to lossy medium). The interaction of radio waves with the human body is a very complex process. The harmful effects of electromagnetic radiation on the human body are believed to be mainly due to the thermal effect of tissue at various penetration depths and non-thermal effects. The thermal effect is particularly harmful to some sensitive organs (such as eyes, testicles, kidneys and liver), and the non-thermal effect mainly affects the autonomic nervous system of the human body. Attention should be paid to the resonance phenomenon presented by the human body or its parts. In fact, the human body resonates in the very high frequency band: its precise resonance frequency is related to body size and body shape.
The main factors affecting the amount of RF energy absorbed by the human body are the frequency, polarization, power density and burst time of the incident wave and the electrical characteristics of the human body.
1.2 Factors affecting the human body's tolerance to RF energy Under certain conditions, the human body has a certain tolerance to exposure to RF energy, which is related to many factors. These factors include the temperature and humidity of the environment, the heat generated or absorbed by the human body and the health of the person being exposed. The safety limit must be taken as the upper limit of the recommended value for normal environment. For example, if the temperature and humidity in the area where the staff are exposed to RF are high, then a safety factor can be introduced to reduce the recommended value cited in the applicable standard. It should be noted that people with poor blood circulation are particularly susceptible to injury due to thermal effects.
Safety radiation limit
The safety radiation limit of microwaves is shown in Table 1
Table 1 Safety limit of microwave radiation
Safety limit
0.038mw/cm2bzxz.net
0.3mw.h/cm2
1~5mw/cm2
When irradiating
8 hours of continuous irradiation per day.
Total dose per day for short-term intermittent irradiation and irradiation for more than 8 hours per day. Workers must use protective equipment, and the daily dose shall not exceed 0.3mw·h/cm\. It is generally not allowed to work in a radiation environment exceeding 5mw/cm*. The safety limits listed in Table 1 are based on the propagation of plane waves or local plane waves, which means that the data listed only applies to the far field of the antenna. In the absence of reflecting obstacles, the far-field power flux density can usually be calculated. However, in the near field, this calculation is very inaccurate, so measurements are required. For near-field situations dominated by reactance fields, the concept of power flux density is not applicable, but the temperature of the electric or magnetic field can be measured, or the square value of the electric or magnetic field that is proportional to the energy density of the electric or magnetic field can be measured. Sometimes these results are used to derive the power density of the equivalent plane wave so that the results are consistent with the standard. For other frequency bands, the safe radiation limits can refer to the data listed in Table 1. 3 Test equipment and test methods For near-field field strength measurements, the test equipment must be calibrated using an appropriate method. There are two calibration methods, namely the standard antenna method and the standard field method. 3.1 Standard antenna method It consists of a standard receiving antenna equipped with a corresponding standard instrument, and the field value can be directly calculated from its readings. The detector on the test equipment to be calibrated is compared with the standard antenna effect at the same field point to perform calibration. 3.2 Standard field method
The key to this method is to establish a standard field whose intensity and spatial distribution can be accurately calculated, and the field amplitude is large, and there is a uniform area that can meet the requirements of near-field measurement. The detector on the test equipment to be measured is placed in the standard field and calibrated according to the standard field.
3.3 Detector
The most commonly used is the "isotropic" detector. This detector is usually composed of three short dipoles that are perpendicular to each other. The induced current on the dipole is detected by a diode, thermocouple, etc.; the three detected signals are combined and amplified. The output of the test equipment is calibrated so that the amplitude of the electric field or its square value can be indicated on the meter or other types of indicators. Some instruments can be calibrated using equivalent power density. 3.4 Precautions during measurement
Special attention must be paid when making measurements, because the detector and its related equipment may disrupt The measured field may lead to erroneous results. In addition, the presence of test staff may also disturb the measured field. It is best to use a remote control device. 4 Dangerous areas
Any area where potential dangers may exist should be measured by test methods, and the areas where the field strength measurement exceeds the prescribed limit should be properly announced to remind staff of possible dangers. The relevant operating regulations of the test field should tell staff any locations where potential dangers may usually occur. Additional notes:
This standard was proposed by the Standardization Institute of the Ministry of Electronics Industry. 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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