- What is EME?
- What is radiofrequency EME?
- Common Sources of RF EME
- Radiofrequency in History
- EME and Mobile Communications
- EME Safety Regulations
What is EME?
Electromagnetic energy (EME), also known as electromagnetic radiation (EMR), is the energy stored in an electromagnetic field. It occurs naturally - the earth, the sun, and the ionosphere are all natural sources of EME in our every day lives.
All forms of EME are collectively referred to as the electromagnetic spectrum. The properties of EME vary with wavelength or frequency and EME from different parts of the spectrum interacts with matter differently. For example, UV light interacts with matter differently to radiofrequency signals.
The electromagnetic spectrum has been harnessed to create a wide range of technologies including radio communications, television, electric power, radar, microwave ovens, magnetic resonance imaging, toasters, cameras, lasers and X-ray machines.
The word "radiation" often brings to mind radioactive materials and x-rays. However, radiofrequency EME does not behave like the radiation from radio active material or x-rays. Radiofrequency EME is transmitted by communications systems as radio waves - electromagnetic waves that have the capacity to transmit sound, music, speech, pictures and other data invisibly through the air.
The World Health Organization (WHO) makes the distinction between different types of electromagnetic energy:
"It is important not to confuse such RF fields with ionizing radiation, such as X-rays or gamma rays. Unlike ionizing radiation, RF fields cannot cause ionization or radioactivity in the body. Because of this, RF fields are called non-ionizing."
WHO Fact Sheet: Electromagnetic Fields and Public Health - Mobile Telephones and their Base Stations, 2000
Further information on the Electromagnetic Spectrum is available from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA)
What is radiofrequency EME?
All radio communications systems use EME in the radiofrequency (RF) part of the electromagnetic spectrum between 3 kilohertz (kHz) and 300 gigahertz (GHz). These include TV, AM and FM radio broadcasting, mobile phones and their base stations, paging services, cordless phones, baby monitors, and emergency and rural communications systems.
Source http://www.emfexplained.info/?ID=25186
This picture shows the typical power of the radio services in the community when transmitting.
Common Sources of RF EME
People have been living with radiofrequency energy in the environment for generations, since the invention of "the wireless". The principles of radio communications and its first technologies date back to the 1880s.
EME in the Environment
This picture is a plot from a spectrum analyser (specialised radio measurement equipment) showing the various radio communications signals measured in a typical community. The plot is taken at one location to illustrate typical radio communication signals present, and to make a comparison of signal level.
This plot shows the environmental EME levels from mobile base stations are similar to other radio services in the community.
Reference EMF Explained: http://www.emfexplained.info/?ID=25186#how_strong_are_the_environmental_levels
EME in the home
Many devices in the home use EME communicate to including cordless phones, baby monitors, WiFi routers, microwave ovens and wireless keyboards. Download a poster from the Australian Centre for RF BioEffects Research (ACRBR) showing EME levels from common devices in Australian homes.
The illustration above shows the exposure level in close proximity to common devices in Australian homes as a % of the public exposure limit. 100% = the maximum public exposure limit
Reference: ACRBR survey in Australian homes (PDF)
Baby monitors are also common devices in homes and testing by the Federal Office of Public Health in Switzerland shows the EME levels from baby monitors range from approximately 33% to 1% of the public exposure level over distance of 20-100cm from the monitor.
Radiofrequency in History
| Year | Milestone |
|---|---|
| 1895 | Guglielmo Marconi transmits his first radio signal |
| 1906 | Lee De Forest invents AM radio |
| 1920s | AM radio commercially broadcast to mass audiences |
| 1925 | John Logie Baird and Charles Jenkins experiment with television - transmitting the first live pictures |
| 1930s | FM radio is commercially broadcast United States Navy pioneers military radar technology |
| 1956 | Black and white TV is introduced to Australia Robert Adler invents the first remote control, the "Zenith Space Commander" |
| 1973 | Martin Cooper makes the first ever call on a hand-held mobile phone |
| 1975 | Colour TV is introduced to Australia |
| 1981 | Telstra introduces the first mobile telephone system to Australia - the MTS007 system using car phones |
| 1987 | Telstra introduces the analogue mobile phone network to Australia - the AMPS or Advanced Mobile Phone System |
| 1993 | Telstra introduces the first digital mobile network to Australia - the GSM or Global System Mobile network |
| 1999 | Telstra introduces the first CDMA (Code Division Multiple Access) mobile technology to Australia |
| 2000 | The AMPS mobile network is turned off and CDMA expanded to rural areas |
| 2003 | Telstra introduces the first third generation mobile network on CDMA |
| 2006 | Telstra introduces Australia's largest and fastest national third generation mobile network, the Next G™ network |
| 2008 | The CDMA mobile network is turned off and the Next G™ network continues to be expanded |
You can find all licensed radio communications in Australia on the Australian Communications and Media Authority (ACMA) Register of Licensed Radio communications.
EME and Mobile Communications
Mobile phones use a low-powered radio signal to communicate with the mobile and public telephone networks. Mobile network base stations also transmit and receive low-powered radio signals to communicate with mobile phones.
The health impact of these radio signals is assessed in two ways. Firstly, it is assessed in terms of the direct impact on the mobile phone user. Secondly, it is assessed in terms of the ambient impact of radiofrequency signals in the environment on the general public.
For a mobile phone, mandatory safety standards limit the amount of radio frequency energy that can be absorbed in a persons head or body. For a base station, mandatory safety standards limit strength of the signal (or radiofrequency EME) that people can be exposed to in publicly accessible areas.
EME Safety Regulations
In Australia mobile network communications are regulated by the Australian Communications and Media Authority (ACMA). For the safety standards for mobile communications and other radiofrequency signal transmissions, ACMA takes advice from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) in the Commonwealth Department of Health and Ageing.
Safety standards are based on careful analysis of the scientific literature (both thermal and non-thermal effects) and are designed to offer protection against identified health effects of EME with a large in-built safety margin.
Since 2002 Australia's safety standard has been based on the safety standard recommended by the World Health Organization (WHO). This safety standard has also been adopted by the United States, United Kingdom and European Union.
