Microwave meter tests

The results varied partly due to the test method, but there were obvious failures.

Explanations can be found under the question mark at the bottom right.

The method

Without any scientific precision and with all due humility, we tested the meters in everyday situations, just as measuring should be taken. Given the circumstances of the tests no conclusions can be drawn about the meters' accuracy in general.

The failures

Both the TriField TF2 and the Safe and Sound Pro II failed to detect the radar-controlled lighting, which was clearly audible through the Gigahertz HFW35C's speakers. The TriField also failed to detect Wi-Fi at 5 GHz, although it found much more Wi-Fi at 2.4 GHz than any other device. The Tenmar TM-190 did not detect the DECT cordless phone.

Trust the peak value?

Pulsed radiofrequency radiation is typically characterised by short bursts interspersed with pauses. This is particularly true of radar, Wi-Fi, wireless networks and DECT cordless telephones, as well as the older 2G/GSM technology used for mobile telephony. The peak value is the intensity of the radiation in each pulse, which is equal in every pulse. When pulsed radiation from DECT and Wi-Fi was dominant, the Cornet ED88Tplus and Gigahertz meters could provide a stable peak value if held still in the same position, unlike other meters whose peak values were constantly varying. Pulsed radiation from more recent technologies is more complicated and constantly changing, so manufacturers of radiation meters have to decide what constitutes a pulse and what does not. The Safe and Sound Pro II meter always showed the greatest difference between mean and peak values.

Test locations

Outside, measurements were taken in a block of flats in a suburb of Stockholm. Radiation from mobile phone masts, as well as from radio and TV transmitters and the neighbours' Wi-Fi networks, was measured in the middle of a yard surrounded by houses. The nearest mast was located on a roof 120 metres away. There was no mast visible from the yard.

DECT was measured in an apartment. According to the meters with loudspeakers, the DECT level was measured at the point where radiation from the neighbour's DECT cordless phone was strongest and most dominant.

Each automatic stairwell light contained a motion sensor. It operates on the same principle as a radar, working at a frequency of around 5,800 megahertz (MHz) or 5.8 gigahertz (GHz). Neighbours in the close vicinity did not have Wi-Fi at 5 GHz, and the measurement was taken at head height, 70 centimetres below the lamp.

We tested the Wi-Fi connection using our own router in a shielded area of an apartment. The background radiation in this area was approximately 4 microwatts per square metre within the 27–3300 MHz frequency range. The router could independently switch Wi-Fi on and off at 2.4 GHz and 5 GHz.

The results

The Cornet ED88Tplus and Gigahertz meters (HFW 35C and HF 59B) have manual volume controls, so the sound level increases and decreases with the intensity of the radiation. The audio function reproduces the modulation of radiation within the audible range — for instance, the pulses of a Wi-Fi signal can be heard.

However, the SaS Pro II speaker reproduces the modulation of the radiation and has automatic adjustment of the sound level. Therefore, unlike the other meters from Cornet and Gigahertz, the sound level does not vary with the intensity of the radiation.

The TriField sound function creates a clicking sound whose frequency increases as the average radiation level increases.

The most useful features are manual volume control and modulation reproduction.

The measurements were taken at the same spot for at least one minute. Dashes in the table for the peak and average values indicate that the radiation frequency was outside the meter's range. Dashes in the 'Average' column and a value in the 'Peak' column mean that the meter only shows the peak value, not the average value.

Test of Microwave Meters
What was tested	Meter	µW/m²
What was tested	Meter	Peak	Average
Radiation from mobile phone masts, radio and TV transmitters, the neighbours' Wi-Fi. In the yard	TM-190	30,4	—
	ED88Tplus	727	—
	TriField	1714	646
	SaS Pro II	3700	248
	HF59B	290	108
	HF59B+UBB¹	1480	580
	HFW35C	52	19
DECT 1880 MHz The neighbour's	TM-190²	5,29	—
	ED88Tplus	310	—
	TriField³	107	32,0
	SaS Pro II	650	7,7
	HF59B	140	3,6
	HF59B+UBB¹	194	9,1
	HFW35C	—	—
Motion sensor 5800 MHz In the stairwell	TM-190	—	—
	ED88Tplus	191	—
	TriField⁴	44	15
	SaS Pro II⁴	40	17
	HF59B	—	—
	HFW35C⁵	620	46
Wifi 2,4 GHz In a shielded area	TM-190	2400	—
	ED88Tplus	3100	—
	TriField	8800	750
	SaS Pro II	2300	17
	HF59B+UBB¹	2000	13
	HFW35C	350	10
Wifi 5 GHz In a shielded area	TM-190	—	—
	ED88Tplus	1700	—
	TriField	39	9
	SaS Pro II	1600	1,2
	HF59B	—	—
	HFW35C	1500	4,6
¹ The HF59B comes with a directional antenna that only picks up radiation from one direction, providing a lower reading than the omnidirectional UBB27-3G antenna, which works in the same way as the antennas in the other meters. The UBB27-3G is purchased separately. ² Tenmar TM-190 could not measure DECT. The reading depends on other sources, mainly wifi. ³ There was no impact on the measurement value, but the ticking in the speaker became irregular. The TriField audio function follows the measurement value and not the modulation. ⁴ Neither the TriField nor the SaS Pro II reacted to the motion sensor. Measurements depend on other sources. The modulation could not be heard in the SaS Pro II speaker. The Trifield audio function does not reproduce the modulation of radio and microwave signals. ⁵ However, the radar pulses could clearly be heard in the HFW35C speaker. The HFW 35C has a directional antenna, and a bandpass filter that only allows 5-6 GHz to pass through was also used here. Both the Cornet ED88Tplus and the Gigahertz meters (HFW 35C and HF 59B) feature a manual volume control for the speaker. This adjusts the sound level according to the intensity of the radiation. The audio function reproduces radiation modulation within the audible range - for instance, the pulses in a Wi-Fi signal. The TriField audio function produces a ticking sound whose frequency fluctuates with the average radiation level. In contrast, the SaS Pro II speaker reproduces the modulation of radiation but has automatic volume control, so the volume does not vary with the intensity of the radiation.

Explanations

Frequency (Hz):: Events occurring during a certain time period. In the electromagnetic world, frequency is expressed in hertz (Hz). It can represent the number of waves or other changes measured per second.
MHz (megahertz): Million hertz.
GHz (gigahertz): Billions of hertz.
Radio waves: Electromagnetic radiation used for transmitting radio signals.
Microwaves: Radio waves with a higher frequency, and therefore a higher energy content.
Microwatts per square metre (µW/m²).: The power density or just intensity of radio waves and microwaves. One microwatt is one millionth of a watt.
Microtesla (µT): The flux density of the magnetic field, often referred to as strength.
Volt per metre (V/m): The strength of the electric field.
dB (decibels): Change from a baseline. +1 dB means an increase of one quarter; -1 dB means a decrease of one quarter. +/-3 dB means twice or half as much. Therefore, each 3 dB increase or decrease means a doubling or halving, so +6 dB is quadrupling from the baseline. The baseline can be chosen arbitrarily, just like a microwave meter's average sensitivity to detecting microwaves. The baseline can be chosen arbitrarily, just like a microwave meter's average sensitivity to detecting microwaves.