Alumni Magazine #5_July 2020_single pages web

is still using a single cellphone, the amount of radiation exposure remains the same whether one is using 4G or 5G technologies. Thus, the first difference is superficial. The second difference could be more concerning, because the frequency of radiation has changed. 4G used frequencies in the range of 4 GHz, and 5G might use frequencies that are some 20 times higher. At present, the maximum frequency of 5G is about 86 GHz, which falls in the so-called millimetre-wave range (note that some countries, including South Africa, spectrum higher than 6 GHz is not open for use yet by regulatory bodies and as such, it cannot be used at present). So, how different are these frequency ranges? Electromagnetic radiation can be described in terms of travelling

There are, in fact, two main differences. First, to support better coverage and faster wireless data transfers, more base stations are needed, which have more antennas radiating electromagnetic radiation in a small area simultaneously. Second, 5G and/or future network generations will use a wider range of frequencies to deliver the required bandwidth, with maximum frequency shifting from 6 GHz to 86 GHz. For the first difference, it should be noted that the electromagnetic radiation is emitted both from the side of the base station and from the mobile device (e.g. a mobile phone). Over the past 20 years, a myth has emerged that the radiation emitting from the base station is harmful to people living close to the base station. This is exactly that – a myth: although an amount of power emitted at the base station is in orders of magnitude higher than that of the cellphone, the power at any point away from the antenna decreases quadratically with the increase in distance. This means that for every two metres one moves away from the antenna, the signal will decrease four times. At a distance of 10 m from the antenna, the signal is a 100th of the signal that leaves the antenna. Unless the antenna is installed in the person’s living room, the electromagnetic radiation received by the person from the cell is insignificant. The number of antennas and signal paths in the same cell also does not matter – even the combined power will be small. Potentially more harmful is the radiation emitted by the cellphone held by the user close to their faces, when this device actively transmits – during a phone call. The electromagnetic radiation causes heating of the adjacent human tissue. However, the amount of power – heat – the cellphone is allowed to generate is heavily regulated and it remains the same for 4G and 5G. Since, irrespective of the number of base stations in the vicinity, the user

we are dealing with – perhaps people just have more time to ponder about the technology as the only way of connecting to the rest of the world at the moment. 5G is a hot technology topic, as its deployment just about started less than a year ago and there was recently some news about Slovenia, in Europe, stopping the deployment of 5G until the health effects of the network are evaluated. So, what is 5G? Is it harmful? And is it in any way related to COVID-19? To answer the first question: 5G is the latest (fifth) generation of cellular wireless networks, used to access the internet and to stay in communication with others via audio and/or video. The answers to the other two questions are maybe and no. To begin explaining the second answer, one needs to look at history. Cellular telephony was introduced some 40 years ago with 1G. Since then, every 10 years we have adopted a new generation – 2G (1990), 3G (2000) and now the widespread 4G (2010). However, cellular network providers have to rush to stay ahead of user data traffic demand. The number of mobile network users keeps increasing – the COVID-19 outbreak and the 25% increase in traffic can just be a short preview of what will become the norm in a few years – thus, adding capacity to the network is an ongoing effort and, in our opinion, even necessary. Every network since 2G has focused on bringing more bandwidth (amount of data that can be transmitted at a given time) and faster data transfer to the user; this remains the goal of migration from 4G to 5G. What is then the difference between 4G and 5G, which would make people so concerned about the influence of 5G on human health? It has to be a difference that is a concern, because 4G has been around for 10 years, so 4G technology itself is clearly not an issue.

waves, called photons. Each photon has a certain energy,

which increases with frequency. It is thus true that 5G emits waves with higher energies, but these energies are in the region between 0.1 and 1.2meV. These energies are non-ionising, because the photon energy is not sufficient to remove an electron from an atom or a molecule (about 12eV is needed for this). Note that the energy from the sun, including the ultraviolet light, has four orders in magnitude higher frequency than millimetre- waves (400-800 THz), and we are exposed to much more energy from the sun. In comparison to the sun’s radiation, the exposure to millimetre-waves will remain much lower. Gamma and X-rays have energies that are ionising, but their frequency spectrum lies above that of visible light. Again, our main concern could be the heating of the face – to the eyes and the skin – because of the absorption of the energy emitted by the headset. Fortunately, our bodies are reflective and do not absorb much millimetre-wave radiation. Thus, it is clear that short-term effects are not problematic –



Made with FlippingBook Ebook Creator