High-frequency electromagnetic field refers to the electromagnetic wave with the frequency of1~ 3000 kHz ~ 300 MHz, and its wavelength range is 1~3000m, which can be divided into long wave, medium wave, short wave and ultrashort wave. High frequency electromagnetic radiation belongs to radio frequency radiation (radio waves) in non-ionizing radiation.
High-frequency electromagnetic radiation is also an electromagnetic wave, which has no ionization and has the characteristics of all waves. Its fluctuation frequency in the medium is f, and the unit is "Hertz" (Hz). In high frequency band, the effect of high frequency near field on human body presents electromagnetic induction, which applies electromagnetic energy to human body.
It is precisely because of electromagnetic induction that the space field strength is often very high. Tens of kilowatts of high frequency furnace can make 0.5m fluorescent lamps shine, and some tuning handwheels are hot. In the high-frequency near field, the electric field component is not proportional to the magnetic field component, which acts on the human body respectively.
Some high-power wireless transmitting equipment has a certain proportional relationship between the electric field component and the magnetic field component, which releases electric field energy in a large spatial range and causes pollution. Main sources: natural radiation, such as solar radiation, electromagnetic field of the earth, lightning, etc.
test method
1, measurement method. For details, please refer to Measurement of Physical Factors in Workplace Part 1 Ultra-high Frequency Radiation and Measurement of Physical Factors in Workplace Part 2 High Frequency Electromagnetic Field.
2. Measuring instruments. The measuring range of high-frequency field strength instrument should be able to cover 10 ~ 1000 V/m and 0.5 ~ 50A/m, and its frequency can cover 0. 1 ~ 30 MHz.
3. Measurement object. High-frequency equipment with the same model and protection shall be measured by representative equipment and its liaison personnel; High-frequency equipment with different models or different protections of the same model and its contact personnel should be measured separately; Each operating position of contact personnel shall be measured separately.