COST BM0704 STSM Report May, 2012.

Overview of EMF sources, their characteristics and exposure conditions

Zlatko ivkovi University of Split, Croatia

Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB)

Host: Georg Neubauer

Austrian Institute of Technology GmbH (AIT) Seibersdorf, Austria

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TABLE OF CONTENTS INTRODUCTION ..................................................................................................................3

OVERVIEW OF EMERGING TECHNOLOGIES .................................................................4

LTE LONG TERM EVOLUTION ...................................................................................4

WLAN WIRELESS LOCAL AREA NETWROK ......................................................... 10

RFID RADIO-FREQUENCY IDENTIFICATION ........................................................ 14

ELECTRIC/HYBRID CARS ............................................................................................ 18

DECT DIGITAL ENHANCED CORDLESS TELECOMMUNICATIONS ................... 24

WiMAX WORLDWIDE INTEROPERABILITY FOR MICROWAVE ACCESS ......... 27

UWB ULTRA WIDEBAND ......................................................................................... 29

WBAN WIRELESS BODY AREA NETWORK ........................................................... 31

WORKERS EXPOSURE ASSESSMENT .......................................................................... 33

TETRA TRANS-EUROPEAN TRUNKED RADIO ...................................................... 33

ATC AIR TRAFFIC CONTROL ................................................................................... 36

TRAINS, RAILWAY POWER PLANTS ......................................................................... 39

WELDING ....................................................................................................................... 41

SUMMARY ......................................................................................................................... 44

BIBLIOGRAPHY ................................................................................................................ 45

ABBREVIATIONS .............................................................................................................. 49

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INTRODUCTION The aim of this STSM was building a knowledge base of EMF sources, their characteristics and human exposure conditions, using the literature search, data obtained from the host group, and in situ observations, especially regarding emerging technologies and workers exposure assessment. The identification and characterization of completely new technologies is very important since their new operating characteristics will most certainly lead to novel emissions and overall EMF human exposure assessment (including measurement methodologies) will have to be established. Therefore, the overview of LTE, UWB, WBAN, WiMAX and electric car system was presented. However, existing technologies change and improve constantly regarding their operational characteristics and applications in which they are used. Hence, the overview of some well-known technologies, including WLAN, RFID and DECT, was also included. The implementation of the EU Directive 2004/40/EC will pose new requirements regarding the evaluation of the workers exposure to electromagnetic fields. The implementation of these requirements will pose a significant challenge to employers, since the exposure will have to be assessed with respect to a specific workplace. Many workplaces are exposed to EMFs. In this work, the special consideration was given to industrial processes (welding), transportation systems (electric cars, trains, railway power plants) and communication systems (TETRA, ATC). For every considered technology, the overview of its operational characteristics was given and, where available, the human exposure assessment together with the measurement methodology was presented. Overview of each technology was based on available scientific papers, technical reports and COST presentations.

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OVERVIEW OF EMERGING TECHNOLOGIES

LTE LONG TERM EVOLUTION

GENERAL INFORMATION Figure 1. Adoption of LTE technology [1] LTE technology is an evolution of the 3G mobile-telephony standard, known as UMTS and the system that evolved from it - HSPA. It is also referred as a 4th generation mobile network (4G). LTE is IP based technology which means the data is transferred in pockets. This technology was first proposed by NTT DoCoMo of Japan in 2004; the LTE standard was finalized in December 2008, and the first publicity available LTE service was launched by TeliaSonera in Oslo and Stockholm on December 2009. In 2011, first commercially available Smartphone was released. LTE Advanced is a major enhancement of the LTE standard approved by ITU, and was finalized by 3GPP in March 2011. OPERATIONAL CHARACTERISTICS Frequency bands Two main frequency ranges are currently being used for LTE: - 800 MHz (790-862 MHz) This frequency range was freed up by the digitalization of

radio and television and is sometimes called digital dividend. This range exhibits excellent propagation properties, and base stations which operate at this frequency can cover wide areas, which is especially suitable for coverage of rural regions.

- 2600 MHz (2500-2690 MHz) This frequency range is more suitable for urban areas where base stations will have to be situated near one another because of high demands for information capacity.

Channel bandwidth LTE works using scalable bandwidths form 1.4 MHz to 20 MHz. The greater the bandwidth, the faster data can be transferred. Uplink and downlink rates LTE should provide maximum download rates up to 100 Mbit/s and maximum upload rates up to 50 Mbit/s with low latency times (end user latency

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ms), at the same time ensuring the smooth handover between adjacent cells, even if the users move at high speed. Transmission schemes The downlink transmission process is based on OFDMA. The data is modulated simultaneously into numerous narrow frequency bands called subcarriers. OFDMA is very resistant to faults, especially regarding frequency fading. The uplink transmission process is based on SC-FDMA. The main advantage of this method is the efficient reduction in energy consumption. LTE also uses multiple antenna technology MIMO by employing double and quadruple antennas. The signal in MIMO system travels to receiver via different paths, which improves the quality and transmission rate of wireless connection. Network structure LTE network structure is cellular. It is based on Evolved UMTS Terrestrial Radio Access network (EUTRAN). Each base station is connected to neighboring base station and to the core network EPC. The cell radius is determined by the traffic volume, and can range from a few meters (micro cell) to larger distances - up to 100 km (macro cell). The automatic reconfiguration of the surrounding base stations is also possible, if the certain base station drops out or new base station is installed. Figure 2. LTE base station [2] HUMAN EXPOSURE ASSESSMENT So far, little is known about the actual emissions produced by LTE base stations in real life scenario. However, it can be assumed that the emissions generated by LTE transmitters will be similar to those produced by GSM and UMTS base stations regarding the similarities in the frequency range, antennas characteristics and transmitter output power, [3]- [4]. Up to now, few studies were performed on LTE base stations which were in testing operational modes, [3]- [5]. The pilot study Assessment of general exposure to LTE transmitters carried out by IMST (Institut fr Mobil- und Satellitenfunktechnik) [3] provided the estimation of exposure at maximum transmitter output power. The results showed that the emissions produced by LTE transmitters are well below the legal limits at all measurement points. At 99% of these points the measured values were below 50% of the legal limits. Although this pilot study clearly showed that the expected values of electric field strength and power density are well below the legal limits, the assessment of exposure with fully functional LTE base stations, in real life scenario, has to be performed.

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MEASUREMENT METHOD FOR LTE BASE STATIONS In May 2012, the Federal Office of Metrology (METAS, Switzerland), has published Technical Report: Measurement Method for LTE Base Stations [6] in which the reference method for measuring field levels of LTE installations in indoor and outdoor environment was presented. Two different methods were proposed: - The code-selective method - allows the assessment of the compliance or non-compliance

of an installation with the legal limit values (reference method). - The spectral method - does not allowed the distinction of two different cells of the same

operator/installation. This method is able to demonstrate the compliance of an installation with the regulation but it fails to prove non-compliance since it suffers from overestimation of the extrapolated field strength (approximate method).

In the following sections the most important parts of the mentioned Report [6] are cited. THE CODE-SELECTIVE METHOD

The code-selective method is based on the determination of the radiated field produced by the CRS signal of the downlink signal transmitted on port 0 [7], according to LTE downlink resource grid, depicted at Figure 6. The CRS transmitted by antenna port 0 (CRS0) carries information on the cell identity number (0 to 503). Measurement of the CRS0 requires a code-selective field probe, a measuring receiver or a spectrum analyzer capable of decoding CRS signals and of quantifying their power.

For each LTE cell i of the base station an extrapolation factor 0RiK is defined as:

0

0

,permitted ,iRi Ri

PK

P

(1.1)

with: 0R

iP - actual radiated power (ERP) per source element (R0 power) of the reference signal

CRS0 of the cell i in W

, permittediP - permitted radiated power (ERP) for cell i in W (including the signal of all antenna

ports of the cell) The measured value of the electric field strength has to be extrapolated to the reference operating mode:

0 0, ,max ,

R Ri h i iE E K

(1.2)

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with:

,i hE - extrapolated value of the electric field strength

0,maxRiE - spatial maximum of the electric field strength per resource element of the reference

signal CRS0 of cell i within the measurement volume, in V/m.

Figure 3. LTE downlink resource grid [2]

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All the cell-specific extrapolated electric field strength values are then summed together as:

2,

1

n

h i ni

E E

(1.3)

with:

hE - extrapolated electric field strength of LTE for a given network, in V/m

Finally, the appreciation value BE is obtained by summing over the contributions ,jnetwork hE of

all networks belonging to the same installation:

1, 2, ...B network h network hE E E

(1.4) If:

limitBE E - installation fulfills the requirements

limitBE E - installation does not fulfill the requirements

FREQUENCY SELECTIVE METHOD

The frequency selective method is based on the power of PSS and SSS signals that are transmitted in one OFDM symbol each, every 10 slots, over a bandwidth of 62 subcarriers (930 kHz + 15 kHz for the center). Measurements of the synchronization signals require a spectrum analyzer with true RMS-detector, a minimum resolution bandwidth of 945 kHz (typical Resolution bandwidth of 1 MHz) and a maximum hold-function. The measurements are performed in ZERO-SPAN1 mode, and the sweep time must be chosen so that the measuring time per pixel does not exceed 70 s, the duration of one OFDM symbol being about 71.5 s. The snapshot of LTE signal measured with spectrum analyzer, working in ZERO-SPAN mode, is shown in Figure 7.

For each LTE-cell i of the base station, an extrapolation factor SSiK is defined as:

,permitted ,

min ,iSS

i PSS SSSi i

PK

P P

(1.5) with:

PSSiP - actual radiated power (ERP) per resource element on the primary synchronization

signal of the cell i in W

SSSiP - actual radiated power (ERP) per resource element on the secondary synchronization

signal of the cell i in W

,permittediP - permitted power (ERP) for cell i in W (including the signal of all antenna ports of

the cell)

1 By applying ZERO-SPAN option in Spectrum Analyzers one can obtain the envelope of the signal in time domain

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Figure 4. The snapshot of LTE signal measured with spectrum analyzer working in Zero

span mode [2] The measured value of the electric field strength has to be extrapolated to the reference operating mode:

max 1..max ,SS SSh i n iE E K

(1.6)

with:

hE - extrapolated LTE electric field strength for a given network, in V/m

maxSSE - spatial maximum of the electric field strength (per resource element) of the

synchronization signals within the measurement volume, in V/m n - number of cells of the base station respectively of the installation In case the measurement instrumentation does only provide the total electric field strength (instead of electric field strength per resource element), an adapted scaling of this total electric field strength value to only one resource element must be performed as follows:

max max

1,

62SS measuredE E

(1.7) with:

maxmeasuredE - max&hold value measured over the whole bandwidth of the spectrum analyzer.

Finally, the appreciation value BE is obtained by summing over the contributions of all

network operators and services as in the previous section. If:

limitBE E - installation fulfills the requirements

limitBE E - no assessment is possible

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WLAN WIRELESS LOCAL AREA NETWROK

GENERAL INFORMATION WLAN is local area network in which a mobile user can connect, through an Access Point, to a wider internet using wireless radio connection. Modern WLANs are mainly based on IEEE 802.11 standards, known as Wi-Fi. IEEE 802.11ac standard is currently under development. By incorporating wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8) and high-density modulation (up to 256 QAM), this standard will enable multi-station throughput of at least 1 Gbit/s and a maximum single link throughput of at least 500 Mbit/s. The finalization of this standard is expected for 2012, with final 802.11 Working Group approval in 2013 [8]. OPERATIONAL CHARACTERISTICS WLAN operational characteristics depend on the employed standard. Table 2 summarizes the operational characteristics for the most prominent IEEE 802.11g, IEEE 802.11n and IEEE 802.11ac standards.

Table 1. Overview of WLAN operational characteristics

802.11 Standard

Frequency Band (GHz)

Channel Bandwidth

(MHz)

Data Rates

(Mbit/s)

MIMO Streams

Modulation Approximate

range (m) Indoor Outdoor

a 5

3.7 20 6-54 1 OFDM 35

120 5000

b 2.4 20 1-11 1 DSSS 35 140

g 2.4 20 6-54 1 OFDM DSSS

35 140

n 2.4 20 7.2-72.2

4 OFDM

70 250 40 15-150

ac 5 80 433, 867

8 - - 160 867-6930

Network structure Network structure of the WLAN is quite simple. Wireless clients (different mobile devices such as laptops, Smartphones, or desktop PCs and workstations equipped with wireless network interface) communicate via radio-signals with APs (usually routers which transmit and receive radio frequencies for wireless enabled devices), which are then connected to a wider internet (Figure 8). Beside this type of structure, WLAN can be used to establish ad-hoc

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connection between two mobile devices. The data in WLAN are transmitted in pockets. Prior to sending data, the logistic information between transmitting and receiving nodes are exchanged, which leads to reduced effective data transfer rate.

Figure 5. Schematic preview of WLAN network

HUMAN EXPOSURE ASSESSMENT Since the WLAN devices are permitted to transmit up to 100 mW, the total amount of power that the WLAN emits is low compared to comparable sources such as mobile phones. However, since WLAN signal can be characterized as a pulsed signal (if the pulse is defined as a sudden change in amplitude with time), some concern was raised about its adverse effect on human bodys internal electrical and electro-chemical system, especially regarding sensitive people and children [9]. In [10] and [11] the measurements of WLAN exposure were performed and the compliance with legal limits was estimated. In [10] the exposure to APs was determined for 222 locations with 7 WLAN networks present in office environment. The WLAN exposure was also characterized in a wireless sensor lab environment (WiLab) at IBBT-Ghent University in Belgium. It was found that the average background exposure to WLAN (when WiLab was off) was 0.12 V/m, and with the WiLab in operation, average exposure increased to 1.9 V/m. As it was shown all measured values were far below limits defined by ICNIRP (61 V/m for 2.4 GHz). In [11] the WLAN exposure measurements were performed in 55 indoor sites in four different countries. The measurements were also performed in public spaces, close to Wi-Fi access points and at a distance of approximately of 1 m from a laptop while it was uploading large amount of data. In all cases, the measured signal levels were far below the limits proposed by ICNIRP or IEEE C95.1-2005. As an additional example, the typical values of electric field strengths for different technologies (including Wi-Fi) are presented in Figure 9 [12].

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Figure 6. The average values and maximum-traffic-values of

electric field strength for different wireless technologies, including Wi-Fi [12] (y-axes electric field strength in V/m, x-axes different wireless technologies)

MEASUREMET METHOD FOR WLAN EXPOSURE ASSESSMENT The overview of the problems that could arise during the measurements of EMF exposure from WLAN devices is given in [13]. WLAN transmission scheme is based on DSSS or OFDM (depending on the type of standard), which leads to a stochastic signal characteristic (rapid variations in time). Moreover WLAN occupies broad frequency band (approximately 20 MHz), exhibits different data transmission rates, uses the same uplink and downlink bands with constant burst power and no fixed duty cycles. Since the broadband probes were found to be inadequate for WLAN exposure measurements, the frequency selective measurements based on a precision antenna in combination with spectrum analyzer are mainly proposed ( [14] and [15]). However, a careful selection of the spectrum analyzer settings is of great importance. The detail overview of spectrum analyzer parameters, for measurements in ZERO-SPAN and MAX-HOLD mode, is given in Figure 10 [15]. The spectrum analyzer, for WLAN exposure measurements, should be equipped with sufficient RBW and a RMS detector. Measurement with the narrow RBW would lead to underestimations of actual RF fields, and a PEAK detector would lead to overestimation due to stochastic signal characteristic. Moreover, WLAN devices do not emit RF waves all the time, but only when the data transmission occurs. This means that highly dynamic, burst-like signals without predefined duty cycle or overall crest factor must be expected. Hence, measurements obtained using MAX-HOLD option only (without correction factors), could lead to an overestimation of the actual time averaged exposure at least by 2-3 orders of magnitude. More realistic measurement results could be obtained by applying BAND POWER or CHANNEL POWER measurement options on the modern spectrum analyzers.

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Figure 7. Proposed settings of the spectrum analyzer for WLAN exposure assessment [15]

In [15] the procedure for WLAN exposure assessment measurements, using MAX-HOLD option, was suggested, together with the correction factor calculation:

1.) Determination of active WLAN channels using WLAN-packet analyzer; 2.) Determination of the duty cycle of the active channels using isotropic antenna in

combination with spectrum analyzer; 3.) MAX-HOLD measurement of the different WLAN channels; 4.) Calculation of the total average electric field

by multiplying the maximum hold value with the root of the appropriate duty cycle.

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RFID RADIO-FREQUENCY IDENTIFICATION GENERAL INFORMATION RFID is wireless technology that uses radio-frequency waves to transmit the signal from a tag attached to an object, for the purposes of the automatic identification and tracking. The electronically stored information in tag can be transmitted up to several meters away with no demand for the line-of-sight visibility. Today, RFID is omnipresent and promising technology that can be used in a variety of applications: electronic article surveillance, access control, supply chain/process chain management, warehouse logistic, tracking, road pricing In 2010 the decreased cost of RFID equipment and increased performance reliability drove to significant increase in RFID usage. OPERATIONAL CHARACTERISTICS There are three main types of RFID systems:

- active RFID technology active tag has its own battery which periodically transmits its ID signal;

- passive RFID technology the tag uses radio-energy transmitted by the reader as its energy source;

- battery assisted passive RFID technology the tag has its own battery, but its activated only in the presence of RFID.

Generally, all RFID systems work on the principle that two-way radio transmitters/receivers send an encoded radio signal to a tag which then receives the message and responds with its identification information. To ensure adequate actions the reader compares the information from the tag with data from databases [16] (Figure 12).

Figure 9. RFID System Interaction

RF signals

Figure 8. RFID logo

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In case of passive RFID systems, the modulation of the backscattered signal is obtained by changing the tags impedance when the tag is mismatched the backscattered signal is high, and when the tag is matched the backscattered signal is low. This procedure provides binary modulated backscattered signal over the time (ASK, FSK, etc.). In active RFID systems the desirable modulation is provided by modulators implemented in RFID tags. The operating frequency (and hence the reading distance range) depends on power requirements, propagation surrounding and type of application. Table 3 summarizes the operational characteristic of RFID systems.

Table 2. Operational characteristics of RFID systems

Application Frequency

range Frequencies

Passive read distance

Transmission of energy

Access Control LF 120-140 kHz 20 cm (1.2 m max.) EM induction Access Control HF 13.56 MHz 20 cm (1.2 m max.) EM induction Access Control Supply Chain/ Process Chain Management

Tracking, Road Pricing

UHF 868-928 MHz 0.5 m (5 m max.) Radio waves

Tracking, Road Pricing

Microwave 2.45, 5.8 GHz 3 m (10 m max.) Radio waves

In development Ultra-Wide

Band 3.1-10.6 GHz 10 m Radio waves

HUMAN EXPOSURE ASSESSMENT Since RFID works in wide frequency range, this system is very interesting from the human exposure point of view. Various scientific studies were performed at both low and high frequency range, [17]- [18]. The typical values of in-situ electric field radiated from RFID system in UHF frequency range were presented in [17]. The reported electric field strengths were below 0.003 V/m. This study was carried out in Hong Kong National Airport and has shown that the measured electric field strength values of the UHF RFID system are far below legal limits defined by ICNIRP. In [18], the near field electric and magnetic fields, radiated by an RFID reader operating at 13.56 MHz, were measured and simulated. The RFID reader was composed of two parallel loop antennas (with total radiated power of 100 mW), often used in anti-theft systems as pass-through gate. Two measurement scenarios were carried out: the first one referred to a human standing in the center of the antenna system, and the second one referred to a human standing beside the system, at a diagonal distance of approx. 1.8 m from the center of the antenna system. The first case referred to a shop customer exposure, while standing between the antennas in the anti-theft gate, which happens only for a brief period of time. The second case referred to a shop employee working beside the anti-theft gate for a longer period (quite possible scenario).

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The measured electric and magnetic fields between antennas, along their common axes at height of 1 m are presented in Figure 14. The simulated and measured results, compared to ICNIRP guidelines, are given in Table 4. As it can be noticed, the results showed full compliance to ICNIRP guidelines.

Figure 10. Measurements results for near a) magnetic, and b) electric field of the RFID anti-theft gate system [18] The near field high-frequency RFID reader exposure of anatomical body models (male, female, child and pregnant woman) was investigated in [19], using the simulation software SEMCAD X. The assessment was carried out for three different reader antenna positions at distances up to 50 cm from the body (output antenna power was set to 1 W). From the results displayed in Figure 15, it can be noticed that all SAR values are below the limits defined by ICNIRP.

a)

b)

Table 3. Simulated and measured near electric and magnetic field strengths (max. values), compared

to ICNIRP guides [18]

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Figure 11. a) Whole-body SAR and b) Peak-localized SAR,

in adult male (Duke) and 6 year old child (Thelonious), as a function of distance and different antenna positions [19]

MEASUREMET METHOD FOR RFID EXPOSURE ASSESSMENT In [20] a measurement setup for 13.56 MHz, according to the IEC TC106/156/FDIS standard, was presented. The setup consisted of a RFID antenna, the electric and magnetic field probes, and the signal generator and an emulator for RFID signal generation. As described by the standard, both direct and spatially averaged exposure measurements were performed over the dense spatial grid. The measurement points and density of the spatial grid depend on the type and position of the used RFID antennas and are described in detail in IEC-62369-1.

Figure 12. Measurement setup for 13.56 MHz RFID system exposure assessment

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ELECTRIC/HYBRID CARS

GENERAL INFORMATION Although the electric cars were developed in 19th century, the mass interest revived in 1990s, primarily due to energy crises and effusive air pollution. The global economic recession in late 2000s led to the increase abandonment of fuel-inefficient SUVs in favor of small hybrid cars. In 2008, Tesla Motors delivered Tesla Roadster, which was sold (in 2011) in more than 1500 copies, in more than 31 countries. In the last few years (from 2009) almost all serious car manufacturers have developed at least one version of the electric/hybrid car. Since the electrical and hybrid technologies were recognized as very promising regarding this area, even more rapid development of the electric/hybrid cars could be expected in the near future. OPERATIONAL CHARACTERISTICS Hybrid vehicles use the combination of gasoline engine and electric motor, while the electric vehicles use purely electrical propulsion. The electric motor of a hybrid car is positioned in the front part of a car as it is shown in Figure 17. The schematic preview of the full hybrid car electric system is shown in Figure 18. The electric energy is stored in the high voltage batteries which are connected with the electric motor via electric cables which are situated below the passengers feet.

Figure 13. Scheme of hybrid car Honda Civic IMA [21]

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Figure 14. Scheme of the full hybrid car electric system [22]

In the hybrid/electric cars, static and ELF magnetic fields are generated primarily due to the currents that flow through the circuits in the vehicle. An example of the starter motor currents in time domain is shown in Figure 19.

Figure 15. Starter motor currents in time domain [22]

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MEASUREMENT PROCEDURE FOR ELECTRIC/HYBRID CAR EXPOSURE ASSESSMENT Since electric/hybrid cars mainly generate ELF magnetic fields, the suitable measurement equipment, for the exposure and legal limit compliance assessments, are DC and low-frequency isotropic magnetic field probes, with suitable amplitude and frequency ranges ( [21] and [23]). In [21], for all metrological studies the frequency-selective measuring system NIFSPEC (developed in-house), in combination with commercially available field probes, was used. This combination enabled the analysis of the real-time analog outputs of the probes. In addition to the magnetic field probes, the motor currents and battery currents were measured using the current probes. The full measurement setup is presented in Figure 20.

Figure 16. The scheme of measurement setup presented in [21]

The measurements for electric car exposure has to be carried out at a certain number of locations inside the electric/hybrid cars, ensuring data collection at the floor, waist and seat levels (passengers feet, knees, chest and head). The template that describes the measurement positions in the car (Figure 21) was proposed in [22]. Moreover, the measurements should be carried out while the car is in stationary state, while it accelerates and brakes, and at different constant travelling velocities.

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Figure 17. Template for measurement positions in electric/hybrid cars [22]

HUMAN EXPOSURE ASSESSMENT The electric/hybrid cars mostly generate ELF magnetic fields. The main exposure is expected from the currents that flow through the cable that connects the high voltage battery with the electric engine (and which is installed close to the passengers). These fields can penetrate the human body and produce an electrical current in it. If the induced body currents are too high, the central nervous system can be excited. The critical issues, regarding hybrid car exposure, are transient and step currents (like the starter motor currents from Figure 19). The measured results of ELF magnetic fields generated by electric/hybrid cars were presented in several studies [21]- [24], and were compared to ordinary gasoline engine cars or other transportation systems. The very thorough measurements of exposure, in different electric/hybrid transportation vehicles, were reported in [21] (three hybrid vehicles, two purely electric vehicles, hybrid track, electric tractor and hybrid urban bus). In all cases measured values of magnetic fields were below the ICNIRP limits. Figure 22 shows the measured magnetic field during the start of the hybrid vehicle.

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Figure 18. Transient magnetic field emission during the start of the hybrid vehicle: top time

domain, middle frequency domain, bottom comparison with ICNIRP guidelines [21] In [25] the measured averaged values of minimum and maximum magnetic fields at different locations in the hybrid car were presented. Additionally, the measurements were performed while car was resting, moving at constant velocity and during acceleration/deceleration. Since the cable was positioned at the left side of the car with batteries below rear seat, it was found that the highest magnetic fields were induced at the rear and at the left side of the car. Similarly, in [23], the ELF magnetic field strength values were measured in the frequency range 0-32 kHz, in four different driving conditions (stationary, traveling 30-40 km/h, 80-100 km/h and high speed cruising) for Honda Civic IMA and Lexus RX 400h. The higher measured values were reported at the rear seats at the feet level, especially at velocities 80-100 km/h. The comparison of the measured ELF magnetic field values in hybrid car (Volvo V60 test vehicle), driven by gasoline and electric engine, was presented in [22] (Figure 25). The measurements were carried out according to template shown in Figure 21. The results showed that the generated magnetic fields are generally lower when the car is driven by electrical engine. The similar behavior was also reported in [24]. This could be due to careful cable positioning in hybrid cars which insures lower overall magnetic field. The mentioned studies showed that although ELF magnetic fields, generated by hybrid cars, show significant alterations (caused by different driving conditions and measurement locations), the measured values are far beneath the ICNIRP guidelines, even for the worst case measurement position near the passengers feet.

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Figure 19. The measured RMS values of the magnetic flux density in the passenger

compartment in a plug-in hybrid Volvo V60 test vehicle when: a) the diesel engine was used and b) the electric engine was used [22]

a)

b)

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DECT DIGITAL ENHANCED CORDLESS TELECOMMUNICATIONS

GENERAL INFORMATION

DECT is digital communication standard primarily used for cordless phone systems. It is flexible digital cordless access system for communications in home, office and public environments, used mainly for voice communication (although the data applications also exist). In January 2011 a low power variant DECT ULE was discussed and in September 2011 first commercially available DECT ULE device was presented. This standard enabled home automation, security, healthcare and energy monitoring applications providing the connection of several DECT devices to the web. Figure 20. The base unit and handset of DECT cordless telephone [26] OPERATIONAL CHARACTERISTIC As it is shown in Figure 27, the DECT system consists of the base station and the handset. DECT works at frequencies 1880.928-1898.208 MHz (17.28 MHz bandwidth) [27]. The 17.28 MHz bandwidth is divided in 10 carriers, separated by 1.728 MHz. DECT uses TDMA transmission scheme with data rates of 32 kb/s. TDMA is based on 10 ms frames having 24 timeslots. The DECT signals are transmitted in bursts which results in a difference between the peak and the average power. The peak power in a burst is 250 mW. Thus, the average power, when it sends only 1 slot out of 24, is 10 mW. The typical average power of a base station is between 10 and 125 mW. MEASUREMENT PROCEDURE FOR DECT EXPOSURE ASSESSMENT The measurement procedure for DECT exposure assessment was suggested in [27] and [28]. The measurement setup (Figure 28) is based on: - DECT telephone; - receiving antenna mounted on the wooden tripod; - spectrum analyzer with the following parameters:

start frequency 1.88 GHz stop frequency 1.9 GHz sweep time: 1 ms

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Figure 21. Measure setup for DECT exposure assessment [28]

On spectrum analyzer one can obtain:

1. the beacon pulses form the fixed part in the frequency domain (Figure 29a) 2. the beacon pulses in the time domain (ZERO-SPAN mode) 3. the detection of incoming call. The incoming call is detected in another carrier in the

frequency domain Figure 29b. To visualize two beacons in time domain (ZERO-SPAN mode) the sweep time must be at least 15 ms since two beacons are separated for 10 ms (Figure 29c)

Figure 22. a) Beacon pulses from the fixed part frequency domain, b) beacon and incoming

call frequency domain, c) beacons from the fixed part time domain [28]

a) b)

c)

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HUMAN EXPOSURE ASSESSMENT In [27] the human exposure assessment to DECT stations was reported. The measuremetns were performed for heights and different distances from the DECT base station in corridors and working places. The measurements were carried out with half-wave dipoles, for all three orthogonal polarizations. As it can be noticed from Tables 5-7 the measured values were significantly lower than maximum permissible exposure levels (the maximum noted power of 40 dBm correspodents to power densiti of 0.03 mW/m2, regarding the wavelength and antenna effective area).

Table 4. Measured power at d=3.6 m, h=1.9 m from DECT base station [27] Polarization a b c Measured power

-50 dBm -55 dBm -61 dBm

Table 5. Measured power at d=4.5 m, h=1.6 m from DECT base station [27]

Polarization a b c Measured power

-65 dBm -40 dBm -64 dBm

Table 6. Measured power at d=5.5 m, h=1 m from DECT base station [27]

Polarization a b c Measured power

-65 dBm -66 dBm -62 dBm

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WiMAX WORLDWIDE INTEROPERABILITY FOR MICROWAVE ACCESS

GENERAL INFORMATION WiMAX is a part of 4G wireless communication technology, designed to provide 30 or 40 Mbit/s data rates up to 50 km radius. In 2011 the upgrade up to 1 Gbit/s was suggested. The potential applications of WiMAX are:

- portable mobile broadband connectivity across cities - wireless alternative to DSL for last mile broadband access - data, telecommunication and IPTV services - smart grids and metering

Although WiMAX was considered to be a replacement for GSM/UMTS technologies, majority thinks that LTE will most probably completely extrude WiMAX in that field. OPERATIONAL CHARACTERISTIC The basic operational characteristics of different WiMAX releases are summarized in Table 8.

Table 7. WiMAX operational characteristics

Release Family Radio Technology

Data rates (Mbit/s) Downstream Upstream

WiMAX rel 1 802.16

MIMO-SOFDMA

37 (10 MHz TDD) 17 (10 MHz TDD)

WiMAX rel 1.5 802.16 2009

83 (20 MHz TDD) 141 (2*20 MHz FDD)

46 (20 MHz TDD) 138 (2*20 MHz FDD)

WiMAX rel 2 802.16m

2*2 MIMO: 110 (20 MHz TDD) 183 (2*20 MHz FDD) 4*4 MIMO: 219 (20 MHz TDD) 365 (2*20 MHz FDD)

2*2 MIMO: 70 (20 MHz TDD) 188 (2*20 MHz FDD) 4*4 MIMO: 140 (20 MHz TDD) 376 (2*20 MHz FDD)

The frequency bands allocated for WiMAX are 2.3 GHz, 2.5 GHz and 3.5 GHz. Currently, fixed WiMAX uses both TDD and FDD, while mobile WiMAX uses TDD only. The fixed WiMAX has channel sizes of 3.5 MHz, 5 MHz, 7 MHz and 10 MHz, while mobile channel sizes are 5 MHz, 8.75 MHz and 10 MHz. MEASUREMET METHODS FOR WiMAX BASE STATIONS The description of measurement setup and procedure for WiMAX exposure assessment is given in [29] and [30]. The operational characteristics of measured WiMAX system in [29] were: 3520 MHz downlink, 3420 MHz uplink, channel bandwidth 3.5 MHz, input power 35 dBm with antenna gain of 18 dBi. The measurement setup was based on the measurement probe connected to spectrum analyzer, as it is shown in Figure 30.

28

Figure 23. Configuration for outdoor measurement with the spectrum analyzer [29]

The RMS detector and PP detector were used together with the MAX-HOLD option during 30 s. In [30] the optimal spectrum analyzer settings were reported (Table 9). Table 8. Optimal spectrum analyzer settings for different channel bandwidths of the WiMAX

signal [30]

HUMAN EXPOSURE ASSESSMENT The assessment of WiMAX exposure in urban environment was presented in [31]. All measurement results showed that the measured electric field strengths, due to WiMAX systems, were well below limits suggested by ICNIRP. The percentages of power density contributions, shown in Figure 31, confirmed that the mobile WiMAX has minor influence to the overall power density.

Figure 24. Percentages of power density contributions of the different signals [31]

29

UWB ULTRA WIDEBAND GENERAL INFORMATION UWB is an emerging technology which is expected to ensure a high speed interconnection for WBAN and WPAN, due to its features of multi-path compensation, lower consume power, high transmission speed and simple structure. Federal Communication Commission defined the UWB signal as the signal that has a ratio of the bandwidth to center frequency larger than 0.2 or a bandwidth larger than 500 MHz. The achievable data rates are cca. 480 Mbit/s. The UWB is expected to work in frequency range 3.1-10.6 GHz. MEASUREMENT EQUIPMENT Narrowband measurements using a spectrum analyzer (e.g. RBW 100 kHz, VBW 3 MHz, RMS-Detector, Band Power, time averaging) and application of a corresponding bandwidth correction factor should be used. Usage of broadband digital oscilloscopes, for UWB exposure assessment, cannot be recommended due to their limited sensitivity and their high price compared to medium class spectrum analyzers [32]. HUMAN EXPOSURE ASSESSMENT The extremely low levels of the human exposure due to UWB communication devices could be expected, since their maximum averaged spectral power density is restricted to -43.1 dBm/MHz EIRP (by the current regulations in the USA and Europe). This means that, even for the 100% spectrum usage, the average EIRP in USA will not exceed approx. 0.5 mW, and in Europe 0.3 mW (since European UWB regulation is more restrictive below 3.4 GHz, between 4.8-6.0 GHz and above 8.5 GHz). Therefore, due to the sensitivity achievable by standard measurement equipment, the exposure assessment in practice will not be possible more than 1-2 m away from the devices [32]. However, since the UWB is main candidate for WBAN networks, which are expected to operate in the near proximity (or even inside) the human body, the careful characterization of its impact on possible adverse effect should be investigated. Up to now, several studies were performed, based on FDTD simulations [33]-[35]. In [33], SA/SAR analysis for multiple UWB pulse exposure was carried out, in frequency and time domain. The SA/SAR calculations were performed for Gaussian pulse limited to -43.1 dBm/MHz EIRP in frequency band from 3.1-10.6 GHz, for the antenna situated near the chest, ear, eye and waist. The obtained results, summarized in Table 10, show that SA/SAR levels are well below safety limits. The similar approach was used in [34] for the assessment of the SAR induced in different human head models (VHP Visible Human Project, CAD, and SAM - Specific Anthropomorphic Mannequin) due to UWB exposure. The obtained results shown in Figure 32 demonstrate that there are no risks for the short-term effects. In [35], a complete calculation of exposure of the human eye (with geometrical resolution of 0.1 mm) to UWB electromagnetic pulses, in the frequency range of 3.1-10.6, 22-29, and 57-64 GHz, was performed. The results showed that the interaction of UWB pulses with the eye tissues exhibits the same properties as the interaction of the continuous electromagnetic waves (CW) with the frequencies from the pulse's frequency spectrum. Moreover, it was shown that

30

under the same exposure conditions the exposure to UWB pulses is many orders of magnitude lower than the exposure to CW.

Table 9. Averaged SA/SAR [33]

Figure 25. SAdB maps inside the head models produced by a single UWB pulse:

a) VHP, b) CAD, c) SAM, (0 dB correspondents to 10 pJ/kg) [34]

31

WBAN WIRELESS BODY AREA NETWORK GENERAL INFORMATION WBAN is technology that will enable wireless communication between several sensors units and a single body unit worn at the human body (one example is). Although the main application of this technology is expected in health care (which could enable telemedicine and mHealth Figure 33) it could also be applicable in sports, Figure 26. WBAN for health care [36] military and security. WBAN is an emerging technology, but its still far from the serious commercialization. OPERATIONAL CHARACTERISTICS WBAN is network technology in which the nodes are placed in immediate proximity to human body. It is planned to have transmit-only sensor nodes, transceiver nodes and high capability nodes [37]. These nodes have to be simple, low cost and energy efficient with very low electromagnetic pollution (which also requires low transmit power). Thus, multihop approach, where a sensor does not transmit data directly to master node but the data is forwarded by several nodes, is expected to be applied. MEASUREMENT PROCEDURES AND HUMAN EXPOSURE ASSESSMENT Since WBAN is expected to work in close proximity to human body, the extensive investigation of possible adverse effects on human health will have to be carried out. Although there are several studies that deal with the impact of human body on WBAN characteristics (e.g. [37]), there is evident lack of comprehensive studies regarding the human exposure assessment. In [37] the UWB was considered as the possible noninvasive WBAN communication system, and UWB channel measurements near human body were performed. The investigation of possible excessive exposure inside the human body, due to 403.5 MHz WPT system for MICS, was reported in [38]. The simulations were performed using phantom model, with a point source situated at 22 mm from the sternum. The obtained SAR values for different input powers (for several MICS devices) are presented in Table 11. As it was shown, the values higher than those proposed by human protection guideline were reported for Capsule Endoscope, and SAR values near the allowed limits were found for Cohlear Implants.

32

Table 10. Required input powers for a WPT system to operate MICS devices, and I g, 109 averaged SAR values for

the given input power [38]

33

WORKERS EXPOSURE ASSESSMENT

TETRA TRANS-EUROPEAN TRUNKED RADIO GENERAL INFORMATION TETRA is a professional mobile radio designed for use by government agencies, emergency services, public safety networks, transportation stuff and the military. It uses FDMA/TDMA with four user channels on one radio carrier with 25 kHz spacing between carriers. TETRA mobile station can operate in two basic modes: direct-mode operation and trunked-mode operation. Although the TATRA system is mainly used for voice or dispatch services, it also supports several types of data communication. TETRA uses /4 DQPSK modulation with data rate of 36000 bit/s. Operational frequency band depends on the country, but the usual operational frequencies are between 380 and 460 MHz. The TETRA transmit power is not constant. The ratio of the peak to RMS power is 3.5 dB. Figure 27. TETRA radio [39]

HUMAN EXPOSURE ASSESSMENT (MEASUREMENTS AND SIMULATIONS) In [40] the project SAFE TETRA was presented. The safety of patients with active electronic implants (pacemakers, implantable defibrillator, etc.) near TETRA emitters was investigated. Additionally, the exposure of the human body caused by the use of TETRA transmitters was investigated, including the evaluation of typical position of a transmitter in use and numerical simulation of exposure scenario. The implants exposed in vitro (phantom with saline water with 0.9 g NaCl/litre, 16 mm under the water surface) were examined. The TETRA transmitter was positioned 10 mm over the water surface (Figure 35), with the feeding point of the antenna directly over connections of the electrodes, since this was found to be the worst position regarding induced power at the input of the implant.

Figure 28. Measurement setup [40]

34

To ensure the worst possible exposure condition, the TETRA transmitter was set to the maximum transmitted power in TMO with the TETRA base station simulator, while the implants were set to most sensitive level. This study included the investigation of 6 different TETRA transmitters form 3 manufactures (4 hand-held devices max. 1 W and 2 transmitters with external antenna max. 3 W) and 27 different active electronic implants from 6 manufactures (21 cardiac pacemakers and 6 implanted defibrillators), which yielded 163 exposure scenarios. The results showed that 24% pacemakers showed interference (inhibition of pulses and detection of fibrillation) up to a distance of 40 cm. The interference (triggering of electric shock because of detection of fibrillation) was reported in 33% of investigated defibrillators but only at the nearest distance to the transmitter. Regarding this study, the safety distance of 40 cm between TETRA transmitter and active electronics was suggested. Beside measurements, the same study included the numerical simulation of exposure using FDTD based software SEMCAD X. The simulations were performed using human body model including 6 postures with 4 different models of TETRA transmitters (24 scenarios) (Figure 36). Although it was show that posture of fingers has a high impact on SAR, the obtained results were below the basic restriction limit for all scenarios (Figure 37). The similar studies were also reported in [41] and [42]. In, [41] the distribution of power absorbed in an anatomically realistic model of the head, exposed to TETRA radios with monopole/helical antenna at different distances, was calculated using simulation tools. All obtained results (including those obtained in [42]) showed the compliance with ICNIRP guideline, regarding occupational exposure.

Figure 29. a) Posture of the human model, b) models of the TETRA transmitters [40]

a)

b)

35

Figure 30. a) Simulation of SAR in the human body model, b) comparison of TETRA

transmitters, c) comparison of postures while using TETRA [40]

a)

b)

c)

36

ATC AIR TRAFFIC CONTROL GENERAL INFORMATION Although both the operators and general public can often be exposed to ATC EMF exposure, the studies that investigate this problem are quite rare. In [43], in-situ exposure to NDB for ATC was reported, while in [44] the same authors reported the study on in-situ occupational and general public exposure to verbal communication ATC system, based on VHF/UHF transmission. The NDB is omnidirectional system that is used for aviation navigation and it consists of NDB transmitters on the ground and ADF on aircraft. NDB signals are carrier modulated signals (by 400 or 1020 Hz) in the frequency range of 190-1750 kHz. The NDB transmitters are located outside the airports, on publically accessible terrain, in the operational mode during the whole day. The maximum radiated powers of NDB systems are about 100 W. Figure 31. ATC tower [45] The radars are also very important part of ATC. Two types of pulsed radars, primary and secondary radar, are used in ATC. Typical PW is 1 s with a PRF of 1 kHz, corresponding to a period duration of 1 ms, which results with DC of 1:1000. The primary radar determines the position of aircraft, while the secondary radar acts as an interrogator (it transmits a query to which the transponder on board the aircraft responds with information about the identity and height of the object) and operates at much lower power levels. Typical air traffic control radars have peak powers of 100 kW or more with average powers of a few hundred watts [46]. MEASUREMENT METHODOLOGIES In [43] several different NDB sites, at different airports, were investigated, and the field strengths at 168 locations were measured. The fields were measured using electric and magnetic field analyzers (narrowband measurements) and the broadband probes. For the narrowband setup these setting were applied: RBW of 30 kHz, RMS detector mode, MAX-HOLD mode during 2 min time interval. Measurement methods for VHF/UHF verbal communication system exposure assessment were proposed in [44]. The measurements were carried out in three transmission centers. The temporal behavior of the VHF signals for 6 days was investigated, and a realistic worst-case duty cycle of 29 % was determined. The measurement method and equipment for ATC radar exposure measurement is suggested in [47]. The proposed measurement setup is based on single-axes E-field antenna for the frequency ranges up to 3 GHz, connected to SRM software. The following measurement parameters were suggested for radar frequency determination: RBW of 5 MHz, MAX-HOLD option applied. Measurement time was suggested to be several minutes since the antenna is

37

only occasionally illuminated by radar. For the peak and average field strengths measurements in Time Analysis mode, the following parameters were suggested:

- Peak: RBW of 6 MHz, PEAK detector, MAX-HOLD - Average: RBW of 6 MHz, AVG detector, average time approx. 6 min

The measurements should be performed in each of the tree-spatial directions separately. HUMAN EXPOSURE ASSESSMENT The measurement results, regarding the exposure to NDB, obtained in [43], are presented in Table 12. Beside electric and magnetic fields, the exposure ratio of an NDB site (defined as a ratio between the maximum measured magnetic/electric field value and corresponding ICNIRP reference level) was calculated (ER

38

The measured EM fields due to VHF/UHF transmission, obtained in [44], showed full compliance with ICNIRP reference values. Electric field varied from 0.2 to 21.1 V/m for occupational exposure, and from 0.007 to 8.0 V/m for general public exposure. The average fields were found to be 5.2 V/m, for workers, and 0.7 V/m for general public.

39

TRAINS, RAILWAY POWER PLANTS Due to the progressive development of the 22.5 kV 50 Hz electrification system of the European high-speed railways, several studies were performed regarding both the electromagnetic compatibility with the previous railway systems operated by DC electrical lines and the human exposure to generated ELF EM fields [48]-[4]. Beside the high currents [48], the large inductors (resonant stopband filters) installed along the railway infrastructure, were recognized as a critical points, [49] and [50]. MEASUREMENT METHODOLOGIES In [49] the measurement setup based on three-axes Hall-effect DC magnetometer for the measurement of magnetic flux density and a Hall-effect probe for high currents connected to multimeter was proposed. The measurements were performed along the spatial grid of 15 points at the distance of 90 cm from the inductor axis. The magnetic flux density and the input currents were synchronously measured with sampling time of 1 s during the train passage along the railway line. The differentiating/integrating measurement scheme was presented in [48] for measurements of all currents at the cross section of the railways. Three types of current sensors were developed covering the full current range up to 20 kA. The setup was realized for the purpose of the examination of EMC of the railway system with its immediate environment. In [51] all measurements were performed using broadband ELF magnetic field probes along the sufficiently dense spatial grid (as shown at Figure 43). EXPOSURE IN TRAINS In [50], a study of EM interference in peacemakers (on board on high-speed trains, due to magnetic field generated by filters along the track) was performed (using different numerical techniques). The comparison of the calculated magnetic fields with the magnetic field safety standard limits, with and without coach present, showed full compliance with safety standards. As it was reported, the magnetic flux density produced by the filters and the corresponding voltages induced on peacemakers by the time varying magnetic flux are clearly below the normative limits. In [51] measurements between cars, in driver compartment, passenger cars, dining car and kitchen were performed (Figure 43). The spatial distributions of electric and magnetic fields over the broad frequency spectrum were recorded. All measured values were within ICNIRP general public levels.

40

Figure 33. Electric and magnetic field measurements in trains [51]

EXPOSURE IN RAILWAY POWER PLANTS In [49], a measurement system and a procedure for the postprocessing of the measurement data was proposed for onsite characterization of the static magnetic eld generated by large inductors installed along the 3 kV DC railway infrastructure. Moreover, the minimum distance from the coil axis, for people with implanted electronic medical devices (e.g., pacemakers), was determined and related to the DC current through the lter. In [51], electric and magnetic fields were measured at generator, power lines and transformer (Figure 45). Magnetic fields (with sharp spatial distribution and significant harmonic content) exceeding the ICNIRP occupational levels (exceeding 1500 T at 16.66 Hz) near power lines were recorded (Figure 46).

Figure 34. Electric and magnetic field measurement environments in railway power plants

[51]

Figure 35. Recorded fields near power lines: a) electric and magnetic fields in frequency

domain, b) spatial distribution of magnetic field [51]

a) b)

41

WELDING OPERATIONAL CHARACTERISTICS The overview of the welding methodologies is presented in Figure 47.

Figure 36. Selection of welding methodologies [52]

In arc welding (MIG/MAG) high currents with complex, non-sinusoidal shape are applied:

- pulsed DC currents of up to several 100 A (Figure 48a); - currents with broad frequency spectrum form DC to several 100 kHz (Figure 49b).

The complex electric currents induce complex magnetic fields at the welders workspace (up to several 100 T at the welders position and few mT on the surface of the torch cable). On the other hand, electric fields can be neglected.

Figure 37. Welding currents: a) pulsed DC currents, b) currents with broad frequency

spectrum [53] HUMAN EXPOSURE ASSESSMENT (MEASUREMENTS AND SIMULATIONS) In [52] the exposure evaluation for welding devices together with calculation of the induced current densities in the human body was reported. Since the measurements performed using broadband probes (used in most studies) were reported as inadequate, the new measurement method was suggested. The measurement setup (shown in Figure 49) based on Time and Frequency Domain View was proposed. The magnetic fields and currents were recorded using

a) b)

42

magnetic field probes and currents clamps, and the obtained results were converted in time/frequency domain using FFT.

Figure 38. Measurement equipment for welding exposure assessment [52]

The measurements based on suggested measurement setup reported the measured fields exceeding reference values up to 21.9 times for MAG welding and 137 times for WIG welding. To examine the compliance with basic restrictions the FDTD simulations, using SEMCAD X, were performed. The current densities in the central nervous system were obtained using VHP (Figure 50). The comparison of obtained results for reference values and basic restrictions is given in Table 13. It can be noticed that the reference values were considerably excided. However, only 26% of the basic restriction was reached.

Figure 39. Visible Human Phantom [52]

Table 12. Comparison of reference values with basic restrictions [52]

Welding Process EQ Reference Value [%] EQ Base Limit Value [%] MIG 354,5 26,2 WIG 179,9 11,7 Resistance welding 659,7 11,2

43

In [54] the description and assessment of uncertainty budget for the previously described setup was performed. The uncertainties due to measurement setup, the field source, the methodology, the influences of environment, as well as the uncertainties arising from combining all these contributions to an overall uncertainty were described. As an example, in Table 14, the established uncertainty budget for AC measurements with ELT-400 is presented.

Table 13. Uncertainty budget for the measurements with ELT-400 field meter [54]

44

SUMMARY In this work a knowledge base of EMF sources, their characteristics and human exposure conditions, was presented, especially regarding emerging technologies and workers exposure assessment. For every technology the operational characteristics together with the human exposure assessment and the measurement methodologies were presented, using the literature search, data obtained from the host group, and in situ observations. The work encompassed overview of emerging technologies (LTE, UWB, WBAN, WiMAX, electric cars), some well-known technologies (WLAN, RFID and DECT) and workers exposure in different environments (welding, electric cars, trains, railway power plants, TETRA, ATC). The gained overview of exposure conditions could help preparing the scientific basis for further studies, as well as for procedures for emerging technologies and workplace exposure assessment, regarding: EMF measurement, EMF calculation, and uncertainties thereof.

45

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ABBREVIATIONS 3G 3rd Generation 3GPP 3rd Generation Partnership Project 4G 4th Generation AC Alternating Currents ADF Automatic Direction Finder AP Access Point ASK Amplitude-Shift Keying ATC Air Traffic Control AVG Average CAD Computer Aided Design CRS Code-Specific Reference Signal CW Continuous Wave DC Duty Cycle DC Direct Currents DECT Digital Enhanced Cordless Telecommunications DECT ULE DECT Ultra Low Energy DMO Direct Mode Operation DQPSK Differential Phase-Shift Keying DSL Digital Subscriber Loop DSSS Direct-Sequence Spread Spectrum EIRP Equivalent Isotropically Radiated Power ELF Extreme Low Frequencies EMC Electromagnetic Compatibility EMF Electromagnetic Fields EPC Evolved Pocket Core ER Exposure Ratio EUTRAN Evolved UMTS Terrestrial Radio Access Network FDD Frequency Division Duplex FDMA Frequency Division Multiple Access FDTD Finite-Difference Time-Domain FFT Fast Fourier Transform FSK Frequency-Shift Keying GSM Global System for Mobile Telecommunications HSPA High Speed Pocket Access ICNIRP International Commission on Non-Ionizing Radiation Protection ID Identification IEEE Institute of Electrical and Electronic Engineers IP Internet Protocol IPTV IP Television ITU International Telecommunication Unit

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LTE Long Term Evolution MAG Metal Active Gas MICS Medical Implanted Communication Service MIG Metal Inert Gas MIMO Multiple Input Multiple Output NDB Non-Directional Beacons NFC Near Field Communications OFDMA Orthogonal Frequency Division Multiple Access PC Personal Computer PP Peak Power PRF Pulse Repetition Rate PSS Primary Synchronization Signal PW Pulse Width QAM Quadrature Amplitude Modulation RBW Resolution Bandwidth RF Radio Frequency RFID Radio Frequency Identification RMS Root Mean Square SA Specific Absorption SAM Specific Anthropomorphic Mannequin SAR Specific Absorption Rate SC-FDMA Single Carrier Frequency Division Multiple Access SRM Selective Radiation Meter SSS Secondary Synchronization Signal SUV Sport Utility Vehicle TDD Time Division Duplex TDMA Time Division Multiple Access TETRA Trans-European Trunked Radio TMO Trunked Mode Operation UHF Ultra High Frequencies UWB Ultra Wideband VBW Video Bandwidth VHF Very High Frequencies VHP Visible Human Phantom UMTS Universal Mobile Telecommunication System WBAN Wireless Body Area Network Wi-Fi Wireless Fidelity WIG Wolfram Inert Gas WiMAX Worldwide Interoperability for Microwave Access WLAN Wireless Local Area Network WPAN Wireless Personal Area Network WPT Wireless Power Transmission