RADIOFREQUENCY (RF) SAFETY
FROM MARCONI AND WATT
TO WW2, 5G AND BEYOND
In 1901, Italian physicist, Guglielmo Marconi, sent the first wireless radio communication across the Atlantic Ocean at 1.75 miles. This was followed by German engineer, Christian Huelsmeyer who, in 1904, invented a very basic but promising system that used radio waves to prevent boats and trains from colliding on foggy days. Then came Sir Robert Watson-Watt who, in 1935, developed the first practical radar system to help the Brits during World War II against the German Luftwaffe in the Battle of Britain. Watson-Watt is considered one of the greatest radio pioneers of our time. The Watson-Watts design was used to construct a network of radar stations along England’s coast known as Chain Home which was used to alert the Royal Air Force to approaching enemy bombers.
Pioneers of radio
Over the next decade patents and inventions in the field of telecommunications soared with Sidney Warner realising the first two-way police FM radio in 1941 and Radio Research Lab developing radar countermeasures (jamming) in the 25 MHz to 6 GHz range in 1944. On its heels came M Williams with his RF spectrum analyser in 1946. In 1951, Charles Hard Townes published the MASER (Microwave Amplification by Stimulated Emission of Radiation) principle which led to the development of the first model of a time-division multiplex system connecting subscriber line by electronic gates handling amplitude modulated pulses. Then, the first digital radio-relay system called ARPANET, the precursor to the Internetv, went into operation in Japan in 1962 using 2 GHz operating frequency.
Over the years, more use cases have found their way onto the radio spectrum as innovative technologies arrived – with some, such as WiFI, requiring ultrahigh frequencies (2.4 GHz) that allow more information to be transmitted per second, while others such as the FM radio, operates in the 87.5 MHz to 108 MHz range. Today the radio spectrum is a colour-coded colossus comprising hundreds of bands allotted by the Federal Communications Commission with frequencies ranging between 6 kHz to 300 GHz. Cellular technology took time to catch up, and it was not until 1978 that first generation (1G) networks would be launched. This was followed by 2G in the early 1990s, 3G in 2005 and 4G at the end of 2009 – all used to, amongst others, transmit and receive signals between mobile phones and base stations using RF waves. 5G is currently being used and required more base stations than 4G which stations was also required to be grouped closer together. And not that far on the horizon 6G is looming with an expected commercial launch date of 2030.
Safety first, always
Despite these incredible inventions and developments over the past decades, concerns about the health risks associated with exposure to non-ionizing radiation (NIR) (FM radio waves, microwaves, visible light, and heat) emerged as early as the 1950s when tracking radars were introduced during World War II. As a result, research was conducted in Russia (then the Soviet Union) on the possible biological effects of microwave radiation which led to different public and worker exposure limits across different countries because of different protection philosophies. As public concern increased, national authorities started introducing legislation and guidelines to govern and limit NIR exposure. One such set of guidelines is the ICNIRP’s guidelines for electromagnetic radiation from mobile towers. This culminated in the International Radiation Protection Association (IRPA) being formed in 1966 to represent national radiation protection societies. IRPA and the International Non-Ionizing Radiation Committee (INIRC) was replaced by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in 1992. The ICNIRP categorise NIR as electromagnetic radiation, electromagnetic waves and fields and infra- and ultrasound. Its standards are developed to promote safety guidelines and ensure people and the environment are protected from electromagnetic radiation. The ICNIRP further sets RF exposure safety guidelines which are all adhered to by FIELDsense with frequency response to ICNIRP (1998), FCC (NCRP) OET65 (1997) and Canada Safety Code 6 (2015).