# Mobile Phone Radiation: Reducing the Risk

## Procedure

### Variables

Manipulated Variable:
The distance that the source of signal is away from the antennae

Responding Variable:

#### How much the cell phone signal changes over distance

Constant Variable:

## Third Trial

#### In this trial the following equipment was used: Spectrum Analyzer, Hewlett Packard Antennae, 300 - 1000 mHz Cellular Telephone, Nokia, 890 - 915 mHz Graphs for this trial are missing because the Spectrum Analyzer's memory for printing went down.

Results In dBm (third trial)

Results In mW (third trial)

By how much the radiation was reduced from the 1st measurement (third trial)

## Analysis of Results

In this experiment I did three trials. First trial was done on the distance of 2cm, 10cm, 20cm and 30cm. Second trial was done on the distance of 1.7m, 4.2m and 5.7 m. The third trial was done on the distance of 0.3m, 1m, 2m, 3m, 4m and 5m. The results for the trials are shown below.

In trial one, over the distance of 8 centimeters the radiation has reduced by almost 48 times, over the distance of 18 centimeters it has reduced by about 119 times and over the distance of 28 centimeters it has reduced by nearly 290 times.

In trial two, over the distance of 2.5 meters the radiation has reduced double and over the distance of 4 meters the radiation has reduced by almost 4 times.

In trial three, over the distance of 70 cm the radiation has reduced by about 5 times, over the distance of 170 cm by almost 28 times, over the distance of 270 cm by nearly 92 times, over the distance of 370 cm by 171 times, and over the distance of 470 cm by about 482 times.

The results above suggest that over short distances the signal decreases rapidly and over long distances it decreases quite slowly. Also after taking a look at the results, one could say that using your cell phone in a public place is not similar to secondhand smoke.

After doing a lot of literature analysis, I have found many interesting facts. There are many kinds of different antennas, for example ones that are very long (old models), ones that come out a bit. Ones that stick out of the cell phone but do not come out and ones that have an internal antenna. As strange as it may seem, the old models of cell phones are the safer ones. Each antenna has a magnetic field around it. For short antennas the magnetic field resembles a doughnut, which is compressed and therefore stretched outwards (towards the brain). As for long antennas, the magnetic field looks similar to a stretched out (vertically) doughnut with a small (and stretched out) doughnut on the top and bottom. Since the magnetic field of a short antenna is closer to the brain than that of an old cell phone, that makes the short antenna mo re dangerous. The new models of mobile phones fool many people, everyone thinks that the current models of mobile phone in production are way safer than the old ones because they are new. However it is completely opposite.

## Conclusion

After taking a look at the results above one could notice that over short distances the radiation decreases more rapidly (approximately 6-10 times distance), and over long distances it decreases quite slowly (between 0.07 and 1.02 times distance). Also, after looking at the results, one could safely say that using a mobile phone in a public place is not similar to secondhand smoke and is actually pretty safe for those around you (but not yourself). However I have to emphasize that these results can't be treated 100% correct, because all trials were made in an enclosed space without radiation absorbing walls. And where the cell phone signal might increase or decrease due to multiple reflections from walls and different objects in the room.

## Recommendations

- The reduction of the cell size, and the increase of base stations, which would dramatically lessen the minimum power needed for communication without interferences.

- When using a mobile phone, the antennae should always be pulled out and away from the head.

- A new type of mobile phone could be made with a longer antennae pointing downwards, and away from the head, instead of a short antennae pointing upwards.

- If buying a mobile phone, one should buy the cell phone with a big antenna instead of small.

- One could use a hands-free device, such as headphones and a microphone so that there will be minimum RF exposure to the head.

If one does not want to use a microphone and headphones, then I would recommend to use the cell phone as on one of the diagrams below:

##### Figure 17. Best: New kind of cell phone with the antenna pointed downward.
Good: Antenna pulled out and away from the head.
Bad: Antenna not pointed away from the head or not pulled out.

## Acknowledgements

I would like to express my thanks to Dr. Garth Wells, (TRLabs, Saskatoon) and Dr. V. Khachikyan (Institute of Power and Communications) for helping me to operate the Spectrum Analyzer and Microwave Signal Generator, and for the useful discussions.

I am very thankful to Mr. Don Field, (CellCheck, Saskatoon) and Dr. K. Mitchell and Mr. H. Olivier (University of Saskatchewan) for giving me several cell phones for my project.

I am also grateful to my mom, Svetlana Petelina for her support, useful advices and helping me do some calculations in IDL, and to my older brother Alex for allowing me to use his computer as much as I need for this project.

## References

Scientific papers:

K. R. Foster & J. E. Moulder, Are mobile phones safe?, Public Health, pp. 23-28, August, 2000

Don Maisch. Mobile phone use: It's time to take precautions. ACNEM Journal, V 20, No. 1, pp.3-10. 2001

Books:

Constantine A. Balanis. Antenna Theory: Analysis and Design, 1997

Websites:

www.cancer-health.org

www.arpansa.gov.au/mph_sys.htm

More pages from www.arpansa.gov.au

news.bbc.co.uk/hi/english/health/newsid_351000/351048.stm

news.zdnet.co.uk/story/0,,t269-s2103167,00.html

www.studiosra.it/news/acnem.pdf

www.doh.gov.uk/mobile.htm

www.cellularbazaar.com/mobile_health.htm

www.tassie.net.au/emfacts/mobiles/cellphones.html

## Project Info

Team size: 1or2

Subject area: Phy/Ast

Project type: Experimental

Project level: Standard

Summary: I collected information and studied the published results on the influence of mobile phone radiation on human health. I came to realize that in spite of many governmental and commercial research conducted, no specific numbers are released for the public. Because of this I decided to measure the decrease of mobile phone radiation at different distances. I found that over short distances (2-30 cm) the radiation decreases quite rapidly: approximately 6-10 times distance. However, over long distances (1-5 m) the radiation decreases quite slowly: between 0.07 and 1.02 times distance. Over the distance of 28 centimeters (the difference between 30cm and 2cm) the radiation decreased by 290 times, therefore I concluded that using a mobile phone in a public place probably is not similar to secondhand smoke. Since the radiation from the mobile phone is mainly determined by the lenght and position of the phone's antenna, I proposed several ways to ease it's influence on the head.

Webpage software used: None

Hardware tools used: Scanner, camera

Source of the idea for project: see Introduction

Special Skills: HTML

Awards:

Junior Award in Physical Sciences (First Place)

The most proffesional presentation in Physical Sciences

Provincial Showcase Special Award