EMF protection phone cases – test

Do mobile phone cases that claim to reduce radiation exposure actually work? We built one ourselves to test its effectiveness in real-life situations, rather than relying on laboratory tests.

A mobile phone only emits the amount of radiation necessary to ensure that it is strong enough by the time it reaches the antenna at the top of the mast. This is controlled by the base station — the device in the mast with which the phone establishes wireless contact via radiation that is usually referred to as microwaves or radio waves. If an obstacle is present, such as a radiation-protective phone case, trees, a mountain or a building, or if the phone user is travelling in a car, bus or train, the base station instructs the phone to increase its radiation output. Once the obstacle has disappeared, the phone is instructed to reduce the radiation again. Therefore, a radiation-protective phone case should have no effect unless the phone was already emitting maximum radiation when the case was put on. That's the theory, at least.

The Wavebreaker's homemade

The Breakwater made its own mobile phone case, meaning no seller or manufacturer of cases or bags is forgotten. To avoid contact with any metal parts on the mobile phone, a box was made from thin cardboard. This was covered with two layers of aluminium tape and the joints were made with a one-centimetre overlap. One short side was left open to allow the mobile phone to be inserted.

Mobil med skal där man ser papp och eluminiumtejp

This radiation-protective mobile phone case has only one opening at the bottom, as shown in the picture. There are no other openings for buttons. The fewer openings there are, the more effective the shielding against radiation.

Test results

Measurements were taken at a distance of 75 centimetres (30 inch) from mobile phones located 2.7 kilometres (1.6 miles) from a mobile phone mast. Our homemade radiation-protective mobile phone cases reduced radiation by between 0 and 80 per cent, depending on the phone, direction and the network technology in use (2G, 3G or 4G). The way in which the Galaxy S6 and the iPhone SE handle 4G is strikingly different.

In the diagrams, the outer circle shows an intensity of 30,000 microwatts per square metre (µW/m²), which was also the maximum reading on the meter. The phone's screen was facing the mast.

Samsung Galaxy S6 version SM-G920F

Diagram utan skal — Galaxy S6. 2G without case.

Mobil med skal — Galaxy S6. 2G with case.

Apple iPhone SE 1st generation model MLXP2KS/A

	Case	Screen	Left	Back	Right
The charts as numbers (µW/m²)
Background		0,14	0,13	0,18	0,13
Galaxy S6 2G	Without	4094	380	7512	1598
Galaxy S6 2G	With	2894	592	3580	1498
Galaxy S6 3G	Without	8,6	0,5	3,9	20,3
Galaxy S6 3G	With	4,5	1	7,2	7,3
Galaxy S6 4G	Without	7752	552	30000	30000
Galaxy S6 4G	With	4298	760	4840	7226
Galaxy S6 4G VoLTE	Without	5164	722	20036	30000
Galaxy S6 4G VoLTE	With	3606	748	3682	5684
Iphone SE 2G	Without	8724	16684	16382	11590
Iphone SE 2G	With	5488	5050	3356	2492
Iphone SE 3G	Without	16,8	8,8	11,9	15,3
Iphone SE 3G	With	–	–	–	–
Iphone SE 4G	Without	700	1162	474	532
Iphone SE 4G	With	114	160	178	90
The intensity of the radiation is measured in microwatts per square metre (µW/m²). 'Background' refers to the level of radiation when there is no phone present, whereas 'Back' is slightly higher because the meter's antenna is then directed towards the mobile phone mast. VoLTE (Voice over LTE) is a technology that uses the 4G network to improve call quality. With the mobile case on, the iPhone SE was unable to connect to the base station in 3G mode, so no measurement results were obtained.

Comment

Although the radiation has decreased, placing metal so close to a radio transmitter can produce unpredictable results. In principle, you are effectively recreating the transmitter antenna of the mobile phone. According to theory, the radiation should not decrease at all because the base station compensates for obstacles. However, this did not happen in our test, which was conducted 2.7 kilometres from the mobile phone mast and behind a house. However, the base station's power control is clearly visible when the mobile phone case suddenly is removed. The radiation from the mobile phone then increases significantly, but the base station regulates it down again.

En linje som går från vänster till höger som stiger kraftigt på mitten och sedan faller tillbaka. — When the cover suddenly was removed, the radiation increased from 2,400 microwatts per square metre to 30,000 microwatts per square metre (the meters maximum). Seven seconds later, the base station had regulated it down to 3,400 microwatts per square metre. With the cover on, the radiation was reduced by 30 per cent. Galaxy S6 and 2G.

How our test was done

Mobile phone on ö rod with meter to the left

The distance from the tip of the microwave meter's green antenna to the mobile phone is 75 centimeters. The phone is placed in a holder made of foam plastic and the rods are made of plastic and wood. The entire stand with the meter can be easily rotated to measure from different directions around the mobile phone. The magnetic field meter at the bottom right acted as a counterweight and handled the logging.

Create sound

The mobile phone must pick up sound in order to transmit it. It is not possible to stand and talk on it because nearby people affect the radiation. Instead, a wooden broom with horsehair was used and scraped against the plastic holder.

4G

When the mobile phones were connected to 4G, the intensity of the radiation became highly variable. At irregular intervals, the radiation increased sharply for a few seconds, while in between, they were transmitting at a significantly lower level. It is these bursts of radiation that are reported in diagrams and tables. Not only did the bursts come at irregular intervals, they also varied in strength, which may have affected the measurements. For example, the measurements show a significant difference in how the Galaxy S6 and the iPhone SE handle 4G.

The meter

Mobile radiation was measured using a Gigahertz Solutions HF 59B with an HF800v2500 antenna (The 'Christmas tree'). No filters were used. This antenna has a directional effect, mainly picking up radiation from the direction it is pointed in. The Gigahertz Solutions NFA 400 logged all the measurement values from the HF 59B.

75 centimeters

The purpose of shielding cases is to reduce the intensity of radiation emitted by mobile phones, which is what we wanted to measure. Therefore, the radiation was measured at a distance from the mobile phone, and for practical reasons, it was limited to 75 centimetres. The effect of the cases on the electric and magnetic fields within a few centimetres of a mobile phone is another question with complicated answers.

How professional tests are done

Professionals ensure that the phone does not connect to a base station, which would increase the radiation emitted by the mobile phone in order to overcome obstacles preventing the radiation from reaching the antenna on the mobile phone mast. They connect a computer to the mobile phone and set the phone's transmitter to a fixed power level and radiation output. Only then can the radiation be measured with and without an EMF protection mobile phone case, and the shielding effect determined.

In reality, a situation like that only arises when the base station has already regulated the mobile phone's radiation to the maximum level, and then the shielding case is put on. The shielding effect of the case and the radiation emitted by the mobile phone for communication with the base station are two different things.