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IP and Mobile Trends and Education
IP and Mobile Trends and Education
Announcements of a new mobile network technology generation (5G) have triggered a series of alarming claims about connected health threats. This is nothing new: this phenomenon is with us since the 1990s; those alarming claims have been made around the launch of UMTS (3G) in the year 2000, and with the start of LTE in 2010, too. This time it is quite a bit heavier than in the past, mainly due to the existence of social networks, which tend to spread alleged “bad news” and alarming stories literally at light speed. Public opinion is first and foremost against the cell phone towers as they are the visible landmarks of the technology. Each time a tower for a cellular network is built or planned to be built in a city or near a rural settlement, there is a new discussion about health issues of mobile phone or network radiation. It is about time to put things back into perspective. I’d like to deal with the reality of mobile network radiation in this post.
My first statement here is: Major exposition of humans from mobile radio technology is from handheld phones, not from base stations!
The reason is very simple. The power of electromagnetic radiation goes down with distance extremely fast when moving away from the transmitter. See the post https://www.grandmetric.com/blog/2018/02/20/explained-pathloss/ from Mateusz Buczkowski in this blog for a general introduction of the concept of path loss.
For a frequency of 1 GHz (typical range for mobile phone networks) the path loss measured in Decibel units is
where r is the distance from the source to the measurement point in meters. This is a formula due to the Japanese scientists Okumura and Hata, who have done endless series of measurements and have compiled them into empirical formulas. The Okumura-Hata formulas are internationally accepted and part of the mobile phone standards and acceptance rules. There are variants for different environments (city, rural) and frequencies, but they all show the same pattern. The formula in very simple terms says: the radiation power goes down almost with 4th power of distance.
Let us try it out: Antenna transmission power is anywhere between 250mW (expressed as 24 dBm) for a Small Cell, and 120W for the largest 5G MIMO arrays (which is 50 dBm). A typical 2G, 3G, or 4G antenna has got a transmission power of 20W (43 dBm).
Let us quickly apply that to a user, standing in a relatively small distance to the transmitter:
A Small Cell is comparable to a WLAN access point, and you can come pretty close. We assume a distance of 10 m and get a path loss of 7.3+37.6=44.9dB. Subtraction of path loss from transmission power gives 24dBm – 45dB = -21dBm, which corresponds to approximately 8 µW. (µW is the 1 millionth part of a Watt)
A 5G macro cell antenna will be placed up on a tower or on the roof of a high building. Height above ground is thus some 30 m, and we assume a position in 100 m distance from the antenna. Path loss can be calculated to as =82.5dB. The received power is 50 dBm – 82.5 dB = -32 dBm, which is less than one µW.
A light bulb has about 60W energy consumption, and the emitted light and heat will be in that range. Since hat home your distance to a light bulb will be 2-3 meters. The impact from the light bulb on your body will be more than a million times higher. In is general consensus in medical and biological research that the only impact of microwave radiation, as the one used in mobile networks, is by heating up the target object.
This post made a reference to the above. The author used some of my figures to create a true „horror“ case of mobile radiation, where radiation in the kilowatt range would hit humans. I want to show with this amendment why his construction is a misconception. The blogger basically uses his understanding of the term „antenna gain“. He claims that I had omitted to include antenna gain in my high-level calculations, and that antenna gain would turn my innocent-looking figures into a real power monster.
What is antenna gain? The term actually sounds like a hidden amplifier, which is a complete misconception. Instead, „directional gain“ would be a much better fit, and should be used in the technical literature. Antennas are passive, with no electrical power connected. They just receive the radio frequency signal from the transmission circuitry and convert it to electromagnetic waves. Since it doesn’t make a lot of sense to radiate in all spherical directions (upwards, downwards) antennas are constructed to focus the radiation into a solid angle, typically 120 degrees wide and 15 to 20 degrees high. For all who have seen the video, I would like to add the basic construction of such antennas (see figure below):
You see the enclosures mounted on the pole on the left-hand side, and a schematic drawing next to it, showing the internal. The enclosure is what people see when they look at a cell tower. Inside you see 12 vertical beams in a 2×6 arrangement, the dipoles. These dipoles are the radiating elements. Each dipole gets only a fraction of the total transmission energy supplied to the antenna. This is where the video goes wrong. He is assuming that each dipole gets the full 20 Watts and with “thousands of dipoles” arrives at his key message. The total energy supplied to the antenna and radiated by the antenna does not change through this arrangement, though. Wave interference will have the effect that the wavefronts generated by the dipoles add up or cancel out depending on the direction. The energy is focused on the angle shown in the drawing. The 5G “Massive MIMO” technology just uses more dipoles (such as 64 in 8×8 or 128 in 12 by 8 configuration instead of just 2×6) and feeds them with dynamically delayed signals, so that the “beam” can move and sweep an area. And never ever are there “thousands of dipoles” used in antenna construction. There is no digital signal processor available today, to do the MIMO mathematics (which is complex matrix multiplication) for that many elements simultaneously and in real-time.
Antenna gain is the result of the radiation focus: The antenna in the picture has got an antenna gain of 15 dB. Which just tells you that in the main transmission direction there is 30 times more power than to the side. The total radiation supplied by the antenna remains unchanged.
By the way: The total transmission power is limited by legal and regulatory requirements. And regulatory administrations in all countries that I know of are adding up the total radiation level from a tower, and not just consider a single antenna.
Let us have a look at phone radiation, then. The phone next to your head is transmitting at a maximum about 200mW (which is 23 dBm). That is at least 10,000 times more than the signal received from the tower. Typical transmission power values of phones are a lot lower, though. The base station at the tower controls the power of the phone. It sets phone transmission power to a level so that all phone signals are received at approximately the same strength. If you are near a tower, your phone will transmit at a minimum level (which is below one milliwatt, again). Only if the reception from the tower is very bad, your phone will be commanded to increase transmission power. It may sound crazy, but: more mobile base stations mean less overall radiation levels.
The power of phone transmission has gone down since the first generations of mobile communication. In GSM phones were allowed to transmit up to 1.0W (sometimes even 2W). You may remember that 20 years ago the typical heavy user was holding the phone against the head, and making voice calls all the time. With today’s smartphones the typical user does hardly make a phone call any more, and instead is holding the phone about 1m away from the face for screen interaction.
The impact of phone radiation since the early 2000s has dramatically gone down. If there was any health effect from mobile phone radiation, we should have started to see it in the meantime. We had millions of users exposed to higher radiation than today in the past 20 years. For example, there is simply no increase in the cancer rates predicted by some people already since the year 2000. None of the studies that are always cited by the alarmist news have ever passed scientific quality reviews. They have been rejected on the basis of selection bias, too small sample sizes, and many other reasons. The WHO and national health administrations give a very critical review of these studies. If you are interested in more details about those aspects, see the following post.
Kurt Behnke received his PhD in Mathematics from University of Hamburg (Germany) in 1981, and his second degree (Habilitation) in 1986. He published more than 20 original research papers, joined the Max Planck Institute of Mathematics in Bonn as a guest researcher, was a Visiting Fellow at Warwick University, and was awarded a Heisenberg Research Grant from German Research Council in 1987. In 1991 he made a career shift to telecommunications, where he worked for Philips Communications on OSI system management applications for fiber transmission systems (SDH). In 1993 he joined the California based startup Raynet, and helped creating the first optical fiber access system. From 1997 on he worked for Ericsson in various national and international assignments. These included a position as Director of Customer Operations for T-Mobile International, and one as Head of Managed Services North Africa and Middle East. He went on old age retirement in 2017, where he keeps himself busy by starting to lecture part time on data communications and mobile networks at a local university, and he has occasional assignments for consultancy in the areas of LTE, 5G and machine-type-communications.
Thank you so much for this very informative article!
Since you proclaim that you are an expert, what kind of worst case scenario test did you do and if ever there was a test how long were the duration, how many Cell transmitter did you use on the same spot and how many cellphone side by side did you test and kindly publish you experiment procedure, duration and data. Since you are a PhD you know what worst scenario means…. tsk tsk tsk tsk
Its nonsense and manipulation. Why don’t you compare 60W X-Ray transmitter to the light bulb? Even amateurs know that different wave length cannot be compared because the impact on the human body is always different.
Wavelengths at visible and below are non-ionizing, and the worst they can do is heat you up. If you don’t feel heat coming from the tower, you’re not being affected. That’s why a lightbulb can only hear your skin, but it can’t give you skin cancer, whereas being in the sun for an hour can–ultraviolet radiation is ionizing at higher frequencies.
Comparing any radio transmitter to 60W light bulb proofs that a writer may have lack knowledge about light and radio waves spectrum. Its total nonsense. Its typical “scientific position” that ignores everything other than what it is currently analyzing.
You clearly do not understand the nature of energy (transmitted and incident) and the electromagnetic spectrum – hence your confusion with light bulb energy vs. radio waves….The physics of EMR is well established (for many decades in fact). And it is absolutely science! Your comments dismissive of the scientific position betray what I can only describe, with all due respect, as ignorance. Unless of course your are proposing a different ‘physics’ to that of Maxwell, Einstein etc.
By way of a brief illustration, let assume you are placed in front of THREE 60w direction narrow beam – alfa, beta and gamma energy generators/transmitters – at a distance of say 2m.
You will find that Alpha particles cannot penetrate intact skin while Beta particles can partially penetrate skin, causing “beta burns”. Gamma and x-rays can pass through a person damaging cells in their path.
Please note that alpha and beta radiation are not forms of electromagnetic radiation, thus are not comparable to this situation described in the blog post regarding exposure to a light bulb vs that of a cell tower, which are both sources of EM radiation.
What ln earth are you talking about? Alpha and beta radiation is NOT electromagnetic radiation… they are highly energetic particles.of matter. Visible light, 5G, infrared are all part of the electromagnetic spectrum (photons) and therefore directly comparable
Fred, Alpha radiation is not electromagnetic radiation (it is a helium nucleus – a particle) and neither is beta radiation (electrons- a particle). You may have dearly held beliefs on the subject but your comments add no value because they are meaningless. A 16 year old school science student would recognize your comments as such.
Fred, to clarify, your are comparing alpha (doubly ionized He) and beta particles (free electrons) with EM radiation, that is particle emission versus EM wave radiation. The “burns” are due to kinetic energy collisions. Gamma and x-ray EM radiation can cause ionization of electrons. As far as 5G frequencies, we are talking about RF adsorption at the water adsorption of frequency of 2.45 Ghz which can cause heating.
Your conversion of dBm to W is wrong in all examples.
Thank you for your time and effort in explaining these concepts. It is refreshing to hear from an expert in the field of EM explaining the magnitude differences that the fear-mongering, google-expert, tin-hat-brigades conveniently disregard. I like the way you bring in the visual spectrum in the explanation – something that everyone can relate to. I am an electronic engineer myself who specializes in wireless communication and am thus constantly bombarded with these conspiracy theories and asked for explanations. I now conveniently now refer all queries to your site. Vielen Dank!
Hi thanks for the explanation. Got a question if you dont mind answering. Was a wondering about the wattage of the satellites being used, as you mentioned power drops off over distance. Been struggling to find much info on how it actually transmittes from the satellites, but if the power is mega high isn’t there a danger of it interacting with planes or even birds in someway. I’m guessing if something was to be hit with a beam in the 500watts range theyd know about
Quick question around the units.
When you run the calculations, you are talking about watt rather than watt per square meter. What am I to infer? That it is the total power output through a cross section of the beam? Or just through a 1 meter square and that the Okumura-Hata formula already includes the inverse square law?
I’ll take your word about the 4th power, though I was taught the “inverse square law,” i.e., second power. Either way leads to the same conclusion that the phone in my hand does more than the tower next door. However, you cite a formula for 1GHz. Doesn’t 5G Work on 60 GHz?
WHAT ARE THE REAL LONG TERM AFFECTS, OF EXPOSURE AND CAN IT CAUSE BIO PHYSICAL RESPONSES IN HUMAN BEING AS WELL AS ANIMALS. REDUCING OUR ABILITY TO FIGHT OF BIO-CHEMICAL OR VIRAL ATTACKS.
Dear Kurt,
Tks very much for your effort and time put on this article. I have some background knowledge to understand and refute with my sceptic friends – who very often fall into the well laid quasi pseudo-scientific arguments that 5G poses health risks – but your explanations have really helped me on a better argument.
Now, I have two questions for you if you would be so kind as to comment, which you may or may not covered already:
1. One common argument is that these frequencies have never been used before in consumer applications… and that this is the wavelength used in a weapon, the Active denial system. I couldn’t actually find the power for the ADS anywhere…
2. I understand TV broadcast bands, have been moved from analogue to digital to free up the UHF band for 4G. Weren’t the analogue TV emission stations powered in the kW to MW?
And if operating on the sub 3GHz, similar to microwave cookers, at a longer and more penetrating wavelength. Should we, therefore, be seeing whole towns and villages near TV broadcast stations with a higher count of cancers, immune diseases or whatever for the past … Why isn’t anyone talking about analogue TV effects on health over the past 50 years or so?
I agree with you that a person’s exposure from the mobile is far higher than from the base station. The loss formula you use has no factor for carrier frequency, yet we know range drops 6dB for every doubling in frequency. Is the formula just for nominal 2GHz LTE and legacy bands? For example, we see 28GHz mmWave loses 109dB at 250m but 900MHz travels much farther.
Thank you for this article, Dr Behnke.
I have a question. What is the need for so many dipoles in one antenna when they do not work simultaneously. Thank you!
Worth noting that the higher power towers will be on the lower frequencies, those that until recently were used for TV. If you look at the information for our local TV transmitter you see that it’s putting out about 500,000W in total! These phone towers are really small in comparison. You’d not want to climb a TV transmitter tower while it was turned on! But we accept TV as comforting, old, technology.
Good morning Kurt.
Congratulations on a well balanced and sane presentation. I thought you deflected some fairly nasty personal attacks with dignity and grace.
Here in New Zealand, we have experienced criminals setting fire to 8 cell towers in the last two days, but our police will almost certainly track them down and prosecute.
Kind regards to you.
Finally some common sense, free of conspiracy and anecdotes.Thank you Kurt for taking the time to explain this, and thanks google for putting it in my search results.
Thank you for your excellent comments. I teach a grad engineering class in RF Design and your analysis is spot on. I also spent a hour listening to a bunch of arguments against permitting 5G base stations in our community and was amazed by how many conspiracy theories there are about the dangers posed by these base stations. People using big technical words they do not understand. Things like “pulsed energy” which, of course, is pretty much the same as 4G. As you point out, anyone worried about the effects of RF energy should immediately stop using cellphones, WiFi, Bluetooth, and, for that matter, microwave ovens. The radiation of 5G from base stations is minuscule in comparison.
Oh trust me when I say when these anti-science crowds win their respective 5G NIMBY wars the next thing they would whine about is how 5G sucks due to the lack of coverage which THEY caused to begin with.
There’s no cure for stupid.
