Unexpected facts on... mobile phone radiation

Choose: Home | About me | Health info | På svenska

XJE	Unexpected facts on... mobile phone radiation

The main conclusion of the article (the more base stations the lower the radiation level) I haven't seen mentioned in any media and as it is the opposite of what people believe, I think it is important info to you.

I have arrived at my conclusions by reading the URL in the references and then apply common knowledge in physics and electronics. And as two independent experts have verified the correctness, I'm very sure I'm not wrong.

I don't work at any mobile phone industry or service provider, nor do I have relatives that do. I don't have any shares in such companies. I want to share this information to reduce the possible health risk for the general public as well as for myself.

Demand close distance to a base station

Claim

If, to be maximally safe, you want to reduce the radiation you get from a mobile phone system, you should have a GSM/3G base station close to you, the closer the better. This claim sounds paradoxical at first, but it is the consequence of the communication being two-way and a system design to save on batteries.

Background

A radio or TV mast radiates lots of power (typically 10'000 W - 500'000 W), a GSM or 3G mast very much less (about 20 W). A base station serving just a small area, like indoors or a mall, only radiates 0.1 - 2 W, just as much as your own mobile phone may do.

A TV mast just sends, and it gets larger coverage the more power it radiates. A GSM/3G mast has to both send and receive. What it receives is sent by a mobile phone, and this cannot send using high power or battery life would be unacceptably short. There is no benefit for the base station to use high power to reach far away as it makes the received signal too weak to pick up. That is why the base station is not using high power; it would not increase two-way coverage.

A mobile phone for GSM transmits using a maximum power of 1 W or 2 W. But to save on batteries, and also to minimize communication interference, power is throttled if close to a base station, it can go lower than 0.01 W. Mobile phones and base stations for 3G have 8 times lower maximum power levels than GSM.

The radiation your body receives is higher from mobile phones nearby than from a base station, if the distance to the base station is more than 3 times the distance to the nearest mobile phone. The physical explanation is that the radiation intensity is in inverse proportion to the square of the distance. If you are using a mobile phone yourself, its radiation is totally dominating (by up to a million times). So you want your phone to reduce its power. It does so if the base station is close. The base station will also reduce its power when transmitting to a nearby mobile phone.

Outdoors using GSM and a power of 1 W you can reach a maximum of 35 km. At 10 km 0.1 W would just suffice, but we need some margin, so it is still 1 W at that distance. At 3 km it becomes 0.1 W, at 1 km 0.01 W, at 300 m 0.001 W. Indoors the above power levels must be increased just as much as the walls attenuate. A typical value for concrete/bricks may be 10 times (measured value at the LTH facility), wooden walls have lower attenuation. Metal facade buildings may attenuate a 100 or 1000 times; it is recommended to have an indoors base station or be at the window while using the mobile phone.

By looking at the received signal strength indicator, you can get a very approximate estimate of the power your phone will use while talking. If the indicator has 5 bars, then:

1 and 2 bars = 1 W
3 bars = 0.1 W
4 bars = 0.01 W
5 bars = 0.001 W

Risks

Are the above radiation levels dangerous? At least short term they are not, people don't drop down dead just by answering a mobile phone call. But there may be long-term effects, which will take a long time to verify. Until that is done, science cannot rule out possible damage to your body. But if such damage will be found, you can be sure that the amount of damage will be lower the shorter time you use the phone and the lower power it has to radiate. As seen above, it radiates 10 times lower power if the distance is 300 m instead of 1 km. At 100 m it is a 100 times lower.

Message

For precautionary reasons it would be good to decrease radiation levels, and close distances to base stations facilitates that. It is a pity people believe it is the other way around, and even get anxious if they have a base station nearby. Migration from GSM to 3G, with its lower power and shorter distances, would also lower the possible risk, not increase it.

If you can choose between today's system with fairly few base stations and thus relatively high power or a system with many more base stations and lower power levels, the precautionary principle tell you to choose the latter. The possible health risk is lower and in all other aspects it is just as good or better.

References

The text above is verified and found with reasonable accuracy technically correct by both a mobile phone designer and by SSI (Swedish state radiation agency). There are detailed info on radiation levels around base stations in "Exponering för radiofrekventa fält och mobiltelefoni".

Choose: Home | About me | Health info | På svenska

XJE	Page last changed 2003-04-06. Originally written 2003-04-06. Email: Jan.Engvald`at`xje.se (change `at` to @). Copyright © 2003 Jan Engvald. May be copied if source is stated.