MyBroadband Investigation – Electromagnetic radiation of 4G, 5G, and Wi-Fi tested
Over the years, various concerns have been raised about the safety of electromagnetic radiation.
It began with a panic in the late 1980s, which continued during the 1990s, about the potential harmful effects of the electromagnetic waves in high voltage power lines.
As GSM cellular technology began to develop during the 1990s, these same fears were applied to radiofrequency waves.
The fear was that if the low-frequency waves used in electrical grids all over the world could cause cancer, then surely radio waves that have frequencies 10 million times greater would be even worse?
After decades of scientific enquiry, this panic proved to be unwarranted.
Scientists concluded that the strength of the magnetic field generated by high voltage power lines that you need to be exposed to must be much higher than most people will ever experience for them to potentially be harmful to human health.
While electromagnetic fields are classified as potentially harmful by regulators around the world, as well as the World Health Organisation, the strength of the electric and magnetic fields need to be taken into account as well as the frequency.
Non-ionising radiation
The current scientific understanding is that below certain power thresholds, electromagnetic waves up to the visible light spectrum are unlikely to be harmful to human health.
This includes the low-frequency waves you find in the alternating current carried by electrical powerlines and the radio and microwave radiation used in wireless telecommunications.
Electromagnetic fields that run at frequencies higher than that of ultraviolet light are known as ionising. Ionising electromagnetic radiation, such as that caused by x-rays and gamma rays, can damage DNA and are known to cause cancers.
Non-ionising radiation, whether 50Hz power lines or 5GHz Wi-Fi signals, can’t damage DNA in the same way.
A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths (Wikipedia)
Inverse-square law and electromagnetic field strength measurement
Many people will intuitively understand that the radiation you are exposed to if you are standing next to the source of that radiation is much higher than if you were some distance away.
This is a principle we experience when cooking food on a stove or over a fire. It is also a major reason why the sun doesn’t scorch us to a crisp – the Earth is far enough away that the radiation from the sun is dramatically reduced.
Physicists have an equation that describes the relationship between the distance from the source of the radiation, and the power or strength of the radiation you are ultimately exposed to.
When it comes to electromagnetic radiation, the relationship is described by the inverse-square law. This is a principle in physics which essentially states that if you double the distance between you and a source of radiation, you quarter the power density or radiation that you are exposed to.
This creates an interesting trade-off in wireless networks when it comes to electromagnetic radiation exposure – the amount of radiation we are exposed to from our phones and Wi-Fi routers likely far exceeds the amount of radiation from a cellphone tower.
To see if we could measure this phenomenon in action, we bought an RS PRO IM-195 three-axis RF field emission detector from RS Components. The field strength meter is rated to measure electromagnetic waves between 50MHz and 3.5GHz.
Safe power thresholds for non-ionising radiation
Guidelines for safe exposure thresholds for non-ionising electromagnetic radiation are published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
In its latest guidelines, which were published in March 2020, the ICNIRP stipulated the following thresholds for the general public in the frequency bands of interest to us:
| Frequency range | Electric field strength Volt per metre (V/m) |
Power density Watt per square metre (W/m2) |
|---|---|---|
| 400MHz–2,000MHz | 1.375× frequency0.5 V/m | frequency÷200 W/m2 |
| >2GHz–300GHz | – | 10 W/m2 |
The World Health Organisation collated the exposure limits from various countries for radiofrequency electromagnetic fields in 2017, and a common lower limit for electric fields was 41 V/m at 900MHz.
This is in line with the ICNIRP guidelines if you substitute 900MHz into the above equations.
Similarly, the most common power density exposure limit for 900MHz signals among the countries the WHO surveyed was 4.5 W/m2.
It is worth noting that the ICNIRP guidelines given above are reference levels intended to be averaged over 30 min across the whole body.
Keep the below limits in mind when looking at the test results below:
- 41 V/m
- 4.5 W/m2
Inside a well-connected office – 1.1 V/m
The ambient electric field inside the office where most of these tests were conducted was between 1 V/m and 1.5 V/m.
Outside suburban home – 1.1 V/m, 0.0024 W/m2
We also tested the ambient electric field strength and power density in the garden of a suburban home. The electric field ranged between 1 V/m and 1.3 V/m. The power density measured between 1.5 mW/m2 and 3.5 mW/m2
On top of ASUS Wi-Fi router – 24 V/m, 0.8 W/m2
When the RF field emission detector was placed on top of an ASUS Wi-Fi router, right next to the antenna, it measured electric fields of up to 25 V/m and power density of up to 820 mW/m2. Less than a metre away from the router the electric field strength dropped back down to around 1.5 V/m.
On top of Huawei 5G Wi-Fi router (Rain) – 11 V/m
Measurements as low as 7 V/m and as high as 20 V/m were obtained from a Huawei 5G CPE Pro H112-370 with a Rain SIM installed.
As with the ASUS router, the detector was placed right on top of the device. The electric field strength decreases significantly when the detector is even a few centimetres away from the router.
Speed tests were conducted from a Samsung Galaxy Note 9 connected to the router over Wi-Fi.
Inverse-square law: Electric field from MikroTik hAP AC2
The following looping video illustrates the effect of distance on the electric field strength measured by the RF field emission detector. Less than 1.5m away from a Wi-Fi router, it only measured the ambient electric field. As you get closer, the measurement spikes to almost 40 V/m.
The same happens for power density, which goes from 3.9 mW/m2 to 3.6 W/m2 — close to a thousand-fold increase.
4G cellphone speed test (detector on phone) – 7 V/m
The following looping video shows how the electric field strength emitted by an LG V50 ThinQ 5G smartphone changes during a speed test to the MTN LTE-Advanced network.
As with the router tests, the detector was placed on top of the phone. The field strength drops significantly when the detector is even a few centimetres away from the phone.
5G cellphone speed test (detector on phone) – 10 V/m
The following looping video shows how the electric field strength emitted by an LG V50 ThinQ 5G smartphone changes during a speed test to the Vodacom 5G network.
As with the router tests, the detector was placed on top of the phone. The field strength drops significantly when the detector is even a few centimetres away from the phone.
Line of sight to a 4G and 5G tower – 1.6 V/m, 0.0035 W/m2
Outside, with a line of sight to a cellphone tower no more than 100 metres away, the RF field emission detector measured an electric field of up to 1.6 V/m and power density of up to 4 mW/m2 (0.004 W/m2).
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