Research on electromagnetic radiation of mobile phones and base stations

At present, mobile phones have gradually become a necessity in modern life, and reports on electromagnetic radiation problems of public mobile phone base stations and mobile phones have gradually increased, and more and more people are paying attention to the health effects of electromagnetic radiation.

This article refers to the address: http://

In general, people think that the public mobile phone base station has a large electromagnetic radiation, which is worried that it will affect the health of the body. For a mobile phone with small size, low power and no obvious antenna, it is considered to be less than the electromagnetic radiation intensity of the base station. Then, which is the greater impact of the electromagnetic radiation intensity of cell phones and public mobile phone cellular base stations? This paper analyzes their electromagnetic radiation by introducing national and international standards for electromagnetic radiation from mobile phones and base stations, as well as specific test data.

1 Definition of “electromagnetic radiation”

In general, electromagnetic radiation is defined as the phenomenon that energy propagates through space in the form of electromagnetic waves.

Electromagnetic radiation occurs in all frequency bands of the radio: from low frequency to very high frequency, as well as higher frequency infrared, visible, ultraviolet, X-ray, gamma and cosmic rays. The amount of energy derived from electromagnetic radiation depends on the frequency of the radio frequency. The higher the frequency, the greater the energy. In general, electromagnetic radiation can be divided into two categories: "ionizing radiation" and "non-ionizing radiation."

For example, the energy produced by X-rays, gamma rays, and cosmic rays is enough to destroy the molecules of the human tissue structure, and even ionize atoms and molecules. This type of radiation is also known as "ionizing radiation."

Most of our common electromagnetic radiation is generated by radio transmitting equipment or industrial, scientific and medical electronic products with a frequency of 9 kHz to 300 GHz. The emission frequency is low and the energy is weak. It is far from the energy that decomposes the molecules. . So this type of radiation is also called "non-ionizing radiation."

2 Electromagnetic radiation limit

2.1SAR value

Internationally, FCC, ICNIRP (International Commission on Non-Ionizing Irradiation Protection), IEEE and other agencies have successively formulated technical standards for measuring the effects of electromagnetic radiation on humans. Usually, SAR (Specific Absorption Rate) is used to represent the unit mass per unit time. Absorbed electromagnetic radiation energy. At present, there are two common standards, one is the European standard 2W/kg, and the other is the American standard 1.6W/kg. According to the SAR value of the technical standard for measuring mobile phone radiation recommended by the International Telecommunication Union and the International Health Organization, the electromagnetic radiation of GSM and narrowband CDMA mobile phones must be within the scope of the international authoritative health organization certification.

In the "Electromagnetic Radiation and Protection" (GB8702-88) standard implemented in China, the public exposure standard is: within 24 hours a day, the average absorption rate of the whole body for any continuous 6 minutes should be less than 0.02W/kg; occupational exposure standard For: 24 hours a day, the average specific absorption rate (SAR) of any system for 6 minutes should be less than 0.1W / kg. Comparing Table 1, it can be seen that the standards currently implemented in China are far stricter than those in other countries.

2.2 Electric field strength and power density

The basic limits for cell phone radiation are measured in terms of SAR values, which are measured in a shielded room. The spatial radio waves we live in are far more complex than the shielded rooms, making it more difficult to accept the concept of SAR values.

China's "Environmental Electromagnetic Wave Sanitation Standards" (GB9175-88) defines the electromagnetic standards for electromagnetic waves in the microwave frequency band.

First-class safety zone: refers to all areas where people living, working and living for a long time under the electromagnetic wave intensity of the environment are not subject to any harmful influence, and the electromagnetic radiation intensity is required to be <10μW/cm2. Secondary intermediate zone: refers to the area where all people who live, work and live for a long time in this environment can cause potential adverse reactions, and the electromagnetic radiation intensity is allowed to be <40μW/cm2.

3 Mobile phone and base station electromagnetic radiation test

In accordance with the actual measurement methods required by the National Electromagnetic Radiation Protection Regulations (GB8702-88) and other national standards, we use EMR-300 radiation measuring instrument, in the relatively shielded shielding room (absolute shielding room, mobile phone has no downlink signal) and other conditions It is possible to operate the mobile phone in the maximum output power state, using analog contrast method and simulation method for different types of GSM, CDMA, PHS mobile phones produced by different manufacturers, respectively, 5cm ~ 8cm, 12cm ~ 14cm from the mobile phone Several tests were carried out at 20 cm. The measured values ​​at 12 to 14 cm and 20 cm are relatively small and meet the relevant limit requirements. And we are more concerned about the 5-8 cm distance that people use mobile phone habits.

The actual test results show that under the experimental conditions, the radiation field strength of different types of mobile phones produced by different manufacturers has certain differences, but the electromagnetic radiation intensity far exceeds the national standard.

We made relevant measurements on a mobile base station.

The test point power density within 5 meters from the base station transmit antenna radius is more than 10μW/cm2 (more than the national standard); the measured value is smaller than 10 meters.

4 Analysis of electromagnetic radiation from mobile phones and base stations

When people use a mobile phone, the mobile phone transmits radio waves to the transmitting base station, and the base station also transmits radio waves to the mobile phone. The antenna of the mobile phone and the receiver are close to the ear. The antenna is only 2 to 5 cm away from the head. The head is in the near-field radiation area of ​​the mobile phone, and the electromagnetic radiation received by the mobile phone is relatively large. From 15 meters to 50 meters, in the case of people in their radiation field, it belongs to the far field radiation range, and the electromagnetic radiation acts on the human body as a whole or in all directions.

The farther away from the antenna, the smaller the electromagnetic radiation intensity. In an ideal situation, the electromagnetic radiation intensity (in terms of power density) at a certain point is inversely proportional to the square of the distance from the point to the antenna, ie: 1 cm from the antenna. The electromagnetic radiation intensity is 100 times greater than the intensity at 10 cm. Assuming that the power of an ordinary mobile phone is 1 watt and a call is made 10 cm from the head, in theory, the electromagnetic radiation intensity received at this time is equivalent to the electromagnetic radiation intensity of 10 meters outside the base station with a power of up to 10,000 watts. In fact, most of the radiated power of public mobile phone base stations is below 20 watts. In this case, the electromagnetic radiation intensity of the public mobile phone base station is less than one-fifth of that of the mobile phone, which is negligible.

The measured results of the electromagnetic radiation intensity of the mobile phone and the public mobile phone base station are also in good agreement with the above theoretical analysis. At a distance of 10 meters from the base station of the mobile telephone base station, the radiation intensity is relatively small, both below 10 μW/cm 2 , and under the experimental conditions described herein, the radiation intensity at a distance of 5 cm from the antenna of the mobile phone is almost 50 mW/cm 2 or more.

In fact, the transmission power of the base station depends on the communication distance between the mobile phone and the base station and the number of users. The existing GSM and CDMA systems use microcellular coverage, and thousands of small power base stations are set, and the transmission power of the base station is reduced. The electromagnetic radiation intensity is also correspondingly weakened. At present, the public mobile communication network is very mature. The coverage radius of some cell base stations is only a few tens of meters. At the same time, the microcell base station coverage system reduces the electromagnetic radiation intensity of mobile phones, because today's GSM, CDMA, PHS and other mobile phones are With power adjustment function, the better the signal searched by the mobile phone and the closer to the base station, the smaller the transmission power. The test done in this paper is carried out under the condition of the maximum output power of the mobile phone. Therefore, in the actual use of the mobile phone, the radiation intensity is much smaller than the measured value.

5 Conclusion

Through the above field test and analysis, we can draw the following conclusions:

(1) Electromagnetic radiation is generated by any radio transmitting device. From this perspective, the absolute "green phone" does not exist.

(2) The radiation limit of mobile phones specified by the current standard is generally 50 times smaller than the radiation dose that may cause danger. Therefore, when using mobile phones, standards should be used.

Stainless Steel Finger Rings

Stainless steel mobile phone ring are mainly made of stainless steel , zinc alloy, the surface for high-end plating; Extraordinary luxurious texture electroplating, excellent  viscous, ring angle Rotate 360 degree and vertical 180 degree is very convenient, slim and lightweight design of integrated mobile phone is more beautiful, hundreds of fashion style.

   It also called: mobile phone ring brackets, mobile phone buckle, finger buckle, mobile phone ring, ring bracket, mobile phone holder, 360 bracket, mobile phone grip Mobile phone ring frame, iphone mobile phone bracket, ring bracket, finger buckle hook, mobile phone ring bracket, telephone stent.
   We also can customize Logo and accroding to your demand products you want. Some design gift is also can be customized. There is nothing we cannot do but something you cannot predict.

Stainless Steel Finger Rings

Stainless Steel Finger Rings,Classic Stainless Steel Finger Rings,Small Stainless Steel Finger Rings,Stainless Steel Mobile Phone Rings

Dongguan Qilong Electronic Co., Ltd. , http://www.venicen-ringholder.com