Among the existing types of radiation, one that is harmful to human beings is called ionizing radiation. ? The radiation of mobile communication base station is not ionizing radiation at all, but electromagnetic radiation with frequency of 0-300 GHz. It will not cause ionization of substances and generally will not destroy the molecular structure, so it will not cause harm to human health in theory.
From June 5438 to February 2008, Tokyo Women's Medical University of Japan compared 322 patients with brain cancer who used mobile phones with 683 healthy people, and found that the use of mobile phones had nothing to do with the incidence of brain cancer. In this regard, Liu Xiaoyong, deputy chief engineer of the Testing Center of the National Radio Monitoring Center, said: "As far as the current situation is concerned, the independent scientific expert group and health institutions have concluded that under the international electromagnetic wave safety standards, there is no conclusive evidence that non-ionizing electromagnetic radiation such as mobile phones and base stations is harmful to human health.
"? The radiation standard power density of base stations stipulated by the state is less than 40 MW/cm2, and now it is less than 8 MW/cm2 in the construction of mobile communication base stations. In practice, this number may be even smaller. It is understood that there are two main ways to evaluate the influence of human body in electromagnetic field at present: one is to determine the electromagnetic field intensity by specific absorption rate (SAR) for portable launch products (such as mobile phones, PADs, etc.) within 20 cm from human body during normal use, and the unit is usually Watt/kg; The other is for the fixed desktop transmitter products (such as communication base stations) which are 20 cm away from human body in normal use, the electromagnetic field intensity is determined by calculating the electromagnetic field irradiation on human body, and the unit is usually microwatt/cm2.
"These two aspects, China's management standards are quite strict, China Unicom (13. 16, 0。 32, 2。 49%) Relevant persons also said that in the actual communication network station building process, considering the superposition of signals between different base stations, general operators will put forward stricter requirements for the actual radiation value of base stations than the national standard.
"Although the power density stipulated by the state is less than 40 MW/cm2, considering that the signals of base stations will overlap in level, the construction of mobile communication base stations will implement the standard of" Regulations on Electromagnetic Radiation Protection "1/5, that is, the power density is less than 8 MW/cm2, which may be even smaller in actual use." ? In this regard, Yuan Yuming, senior engineer of Environmental Testing Center of China Metallurgical Construction Research Institute Co., Ltd., conducted some special tests. The test results show that the radiated power density of some wireless routers can reach 127 in the nearest place.
6 MW/cm2, the power density is still 1mw/cm2 at a distance of half a meter, which is almost more than 10 times that of the communication base station. ? Has nothing to do with radiation appreciation? When the signal is bad, the mobile phone will spontaneously increase its power to establish contact with the base station. Therefore, the denser the coverage of high-speed 5G network base stations, the better the cell phone signal, and the smaller the radiation impact on users? According to experts from ZTE, electromagnetic waves decay rapidly in the air, and the intensity of electromagnetic radiation is inversely proportional to the square of the distance, which means that theoretically, the farther away from the communication base station, the smaller the impact on the human body.
For example, when the distance increases by 10 times, the electromagnetic radiation is1100. A test report submitted by China Unicom during the construction of the 20 1 1 WCDMA base station shows that the power density obtained at the test points outside its test base station12-16m is only 0. 06—0。 10 MW/cm2, and the power density at a distance of 2 meters from the base station is 3.
49—3。 Between 78 MW/cm2, as for the floor directly below the base station, the power density is as low as 0. 0 1 microwatt/cm2. "This is mainly because the electromagnetic wave of the base station is mainly emitted in the horizontal direction, and the vertical direction is obviously weak, so the power density directly below the base station is often the smallest. The industry has given an image saying,' Black under the lamp'.
The above experts said that in this sense, ordinary home users really don't need to have too much scruples about living under mobile communication base stations. ? So can this be simply defined as the farther away from the base station, the healthier it is? Of course not. According to Gao Yougang, a professor at Beijing University of Posts and Telecommunications, in fact, when people use mobile communication services, the mobile phone is a more threatening radiation source, because it is closer to the human body, so finding ways to reduce the power of the mobile phone is the key to reduce the radiation of mobile communication.
He said: "The higher the density of mobile communication base stations, the lower the electromagnetic radiation intensity of each base station; The closer the mobile phone is to the mobile communication base station, the lower the electromagnetic radiation of the mobile phone to the caller during use. " According to his test, when the signal strength of the mobile phone shows "one grid", the transmission power of the mobile phone is above 1 watt; When the signal strength shows "five squares", the transmission power is only 0. About 1 watt
Based on this analysis, urban residents are busy "dismantling" the base station in the community, and as a result, the mobile phone signal is not well received, so they have to spontaneously increase their power to establish contact with the base station, which actually increases the radiation hazard to themselves. This is actually an unwise practice. ? Similarly, for the 5G network that the three major operators are currently building at a high speed, the denser the coverage of base stations, the better the reception of mobile phone signals, and the less the radiation impact on users. "The speed of 5G network transmission is mainly achieved through the expansion of transmission bandwidth, just like the highway widening project, which is not directly related to the signal transmission power of the base station." According to the introduction of the above-mentioned mobile people, the frequency bandwidth of the three major operators in the 4G era is generally at the level of 1-5 MHz, and it has been raised to 20MHz in the 5G era. With the increase of frequency bandwidth, the network speed of 5G has been obviously improved, but the radiation standard of 5G base stations should comply with the relevant national regulations, and it will not be greater than 40 MW/cm2, so even if the base stations are densely built, the radiation will not increase.
According to the plan of China Mobile, a leading provider of 5G networks, by the end of this year, the total number of 5G base stations in China will reach 400,000, and the signal coverage capacity will be equal to that of 4G networks. "With such a high-density network coverage, not only will people's 5G wireless life enjoy the convenience of interconnection anytime and anywhere, but also because of the perfect signal coverage, the mobile phone search network is faster and users are less radiated by mobile phones.