Electromagnetic field densitometers measure the exposure to electromagnetic radiation in certain ranges of the electromagnetic spectrum. This article concentrates on densitometers used in the telecommunication industry, which measure exposure to radio spectrum radiation. Other densitometers, like extremely low frequency densitometers which measure exposure to radiation from electric power lines, also exist. The major difference between a "Densitometer" and a "Dosimeter" is that a Dosimeter can measure the absorbed dose, which does not exist for RF Monitors. Monitors are also separated by "RF Monitors" that simply measure fields and "RF Personal Monitors" that are designed to function while mounted on the human body.
Most of the scientifically proven RF safety monitors are designed to measure the RF exposure as a percentage of the two most common international RF safety guidelines: International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines[2] and the U.S. Federal Communications Commission (FCC).[3] The ICNIRP guidelines are also endorsed by the WHO.[4] RF Personal Safety monitors were originally designed for RF Engineers working in environments where they could be exposed to high levels of RF energy or be working close to a RF source, for example working at the top of a telecommunication tower, or working on the rooftop of a building with transmitting antennas present. Most international RF safety programs include the training and use of RF Personal safety monitors and the IEEE C95.7 specifies what an RF Personal Monitor is.[5]
In some cases the RF safety monitor comes in a version or mode for the general public.[6] These meters can then be used to determine areas where the public might be exposed to high levels of RF energy or it might be used to indicate the RF level at areas where the general public has access.
The specifications of a RF monitor determines the work environment it can be used for. Wideband RF monitors can be used at a broader variety of base station site types than for example a narrowband, cellular RF monitor which is designed only to be used in the mobile telephone- and data networks. The IEEE C95.3 states an "RF Personal Monitor in the region of 1-100 GHz, resistive thermoelectric dipoles are used as sensors with a background of lossy material to reduce the effect of scattering from the body". Monitors which do not incorporate "lossy material" to reduce the effects of scattering, their results are questionable on the body. Below find a table with the different basic specifications of some RF monitors:
Specification | EME Guard XS [7] | Narda Radman Mobile [8] | SafeOne [9] | fieldSENSE [10] | EME Guard [11] | Nardalert S3 [12] |
---|---|---|---|---|---|---|
Frequency Range | 80 MHz – 6 GHz | E-Field 50 MHz - 6 GHz
H-Field 50 MHz – 1 GHz |
10-10000 MHz | E-Field 380 MHz- 2.7 GHz | 27 MHz- 40 GHz | 100 kHz- 50 GHz |
Directivity | Isotropic (Tri-axial) | Isotropic (Tri-axial) | Isotropic (Tri-axial) | Vertically Polarized | Isotropic (Tri-axial) | Radial and Dual-polarized |
ELF Immunity | N/A | 1 kV/m | N/A | N/A | N/A | 100 kV/m |
Designed to be worn on the Body (per IEEE C95.3) | No | Yes | No | No | No | Yes |
Reference standard | ICNIRP
FCC Safety Code 6 User-definable 2004/40/EC |
ICNIRP
FCC Safety Code 6 |
ICNIRP
FCC IEEE NCRP Safety Code 6 |
ICNIRP
FCC IEEE NCRP |
ICNIRP
FCC Safety Code 6 User-definable |
FCC
IEEE C95.1 Safety Code 6 (2015) ICNIRP |
Exposure level indicators | 1 X LED => 1%
2 X LED => 5% 3 X LED => 20% 4 X LED => 100% 5 X LED => 225% 6 X LED => 500% 7 X LED => 2000% (Broadcast 100 MHz: Visual & Audio Alarms Activated 5 to 350 V/m User-definable at factory) |
1 X LED => 12.5%
2 X LED => 25% 3 X LED => 50% (Buzzer alarm) 4 X LED => 100% (Buzzer alarm) |
1 X LED => 5%
2 X LED => 15% 3 X LED => 40% 4 X LED => 63% (1 Hz buzzer alarm) 5 X LED => 100% (1 Hz buzzer alarm) 6 X LED => 160% (2 Hz buzzer alarm) 7 X LED => 250% (4 Hz buzzer alarm) |
1 X LED => 25%
2 X LED => 50% 3 X LED => 75% 4 X LED => 100% (Vibrator and buzzer alarm user-definable) |
LED Display of the Actual Value
Two LED Alarm Indicators (Visual) Two Audio Alarm Indicators Vibration Alarm Indicator User Variable in 5% increments Defaults are 50 and 200% |
|
Data logger | No | No | No | No | Yes | Yes |
Battery life | >100 hours | 200 hours | 2,000 hours | 250 hours | >100 hours | > 40 Hours (Rechargeable via USB) |
Dimensions | 132.5 x 48.5 x 28.7 mm | 157 X 36 X 26 mm | 58 x 105 x 23 mm | 132 X 41 X 23 mm | 172 X 60 X 35 mm | 120 x 83 x 32 mm |
Weight | 120g | 130g | 88g | 91g | 320g | 230g |
Operating temperature | -10⁰C to +50⁰C | -10⁰C to + 55⁰C | -10⁰C to +40⁰C | -10⁰C to +50⁰C | -10⁰C to +50⁰C | -10⁰C to +50⁰C |
Calibration interval | 24 Months | 36 Months | 24 Months | 24 Months | 24 Months | 48 Months |
NIST Traceable Calibration | No | Yes | No | No | No | Yes |
Approx. price USD | $550 | $700 | $700 | $500 | $1800 | $1700 |
Each specific personal RF safety monitor has its own operating instructions. And most of the monitors have different operating modes. For instance, the Narda Radman has a mode in which it can be body worn by the operator, but it also has a probe mode where the operator can scan certain areas to find accurate exclusion zones.[13] The fieldSENSE on the other hand has a monitor and measure mode.[14] The measure mode is similar to the Radman’s probe mode, but the monitor mode is used by mounting the fieldSENSE onto an inactive antenna and then it is safe to work on the antenna until the fieldSENSE raise an alarm to warn RF technicians that the antenna is live and that any work on the antennas should be ceased until deactivation is confirmed. A few of the newer models of RF monitors such as the EME Guard also have a data logging functionality that can log the RF exposure of a worker over time.[11][15]
EME Guard XS Safety Monitor for RF. https://handwiki.org/wiki/index.php?curid=1084448
Occupational fieldSENSE unit. https://handwiki.org/wiki/index.php?curid=1302380
Scan for leak in RF feeder. https://handwiki.org/wiki/index.php?curid=1371690
Nardalert S3. https://handwiki.org/wiki/index.php?curid=1638961
The content is sourced from: https://handwiki.org/wiki/Physics:Personal_RF_safety_monitors