Assessment of Electromagnetic Radiation Exposure of Embarked Personnel on Romanian Naval Ships Georgiana Marin
Gheorghe Samoilescu
Ship physical fields Research Center for Navy Constanta, Romania
[email protected]
Electrical engineering department “Mircea cel Batran” Naval Academy Constanta, Romania
[email protected]
Octavian Baltag
Serghei Radu
Medical bioengineering department University of Medicine and Pharmacy Iasi, Romania
Chief engineer Barklav Shipping Agency Constanta, Romania
Abstract—The issue of electromagnetic compatibility and bioelectromagnetic compatibility is critical onboard ships, especially on naval ships, characterized by a large number of antennas transmitting in various frequency range, and placed in a small area. The paper presents some measurements performed on a Romania naval ship, in order to determine whether the personnel onboard is exposed to dangerous electromagnetic radiations. There were considered several high traffic areas on the ship, and measurements were performed in two frequency ranges: 80-200 MHz and 200-2500 MHz, respectively. The results represent measurements of the far-field of antennas. Compared to the electric field strength limits for controlled environments imposed by European regulations, the measured values were definitely lower. Keywords-bioelectromagnetic compatibility; electric measurements; particular electromagnetic environment
I.
During the electromagnetic radiations interaction with the tissues, they are causing damaging biological effects. The destruction level depends on factors such as intensity, frequency, polarization, and exposure duration. The response may be thermal or non-thermal. After the radiations have penetrated the tissue, its dielectric and conductive properties modify the absorption and propagation of the incident energy. Extreme reactions have been noticed at the exposure to electromagnetic weapons. Fig. 1 illustrates the effects of electromagnetic weapons on people, according to several admitted reports [5].
field
INTRODUCTION
The issue of protecting the human factor against the exposure to electromagnetic fields has been extensively treated by specialists. In order to determine the exposure of personnel on board ships, electromagnetic field measurements were performed at various points on board a naval ship. The measurements took place in distinct stages, for two frequency ranges. Given the complex phenomena of harmful interference onboard, the research was directed mainly towards high energy density and high traffic areas. II.
ELECTROMAGNETIC RADIATION EXPOSURE EFFECTS
Recent research on non-ionizing electromagnetic fields have shown their influence on living organisms, acting in a complex manner on intracellular phenomena, cells, organs and thus on the body as a whole [1-4]. Numerous studies especially in recent years have led to the conclusion that the idea those non-ionizing electromagnetic radiations have no effect on living systems is completely false.
Figure 1. Symptomatic forms of manifestation due to exposure to electromagnetic weapons
Although occupational exposure is not as damaging as exposure to electromagnetic weapons, there are manifested various concerns regarding the exposure of personnel onboard military aircraft and vessels, due to the large number of transmitters therein. III.
THE ONBOARD ELECTROMAGNETIC ENVIRONMENT
Sources of electromagnetic interference onboard warships cover a wide frequency range from 50 Hz to 20 GHz, and include generators and electric converters, electric motors and drive facilities, radio and radar systems, telecommunications systems, computer network, source of discharges, mobile radiotelephones. The main sources of radiation on board are the communication antennas radiating through all metallic structures nearby. There are three types of onboard transmitters: - Stationary - multidirectional transmission HF, VHF, UHF; - Rotating - 2D and 3D radars, some of which emit high power pulsed energy (air surveillance, sea surface surveillance, navigation radars); - Direct beam - fire control systems, electronic warfare radars, satellite communication antennas.
For proper measurement, the ECC Recommendation was followed [7]. There were taken into account other in-situ measurement indications [8, 9, 10]. Measurement points were situated at 1.5 meter height. Since measurements were performed for overview purpose, the field values represent single point measurements. For analysis, there were adopted two measurement ranges: 80-200 MHz and 200-2200 MHz, respectively. The research consisted in field measurements performed in several high traffic areas: inside the bridge, outside the bridge, on the respective deck, and on the heliport deck. The reason for selecting those areas is that they are usually transited by the officer of the watch and crew members. The measurements were performed in port area, the ship berthed. First there were determined the ambient field values in selected onboard areas, without any operating communications or radar station. Then there were performed electric field measurements on the selected areas, during the operation of indicated transmitters. Figs. 2 and 3 illustrate the measurements of ambient electric field strength, performed outside the bridge, for the selected frequency ranges: 80-200 MHz and 200-2200 MHz.
The operational profile of a naval ship consists in stationary periods, the ship berthed, for crew training and ship maintenance, and sea-going periods, for performing specific missions. In order to determine the exposure level onboard a naval ship, during its stationary and sea-going periods, several measurements were performed. IV.
FIELD MEASUREMENTS ONBOARD A ROMANIAN NAVAL SHIP
The device used for measurements is a portable electric field meter with isotropic TS-EMF probe, with frequency range 80 MHz – 2.5 GHz, measurement range 1 mV/m – 100 V/m. The data was fed to a spectrum analyzer with 9 kHz – 13 GHz frequency range, -140 – +30 dBm, RBW 10 Hz – 10MHz [6]. For all measurement stages, the spectrum analyzer settings are described in Table 1. TABLE I.
SPECTRUM ANALYZER SETTINGS
Parameter
Trace Mode Detector Resolution Bandwidth (RBW) Video Bandwidth (VBW)
Setting
Max Hold RMS 1000 kHz auto
Span
1000 MHz
Reference level
93 dBµV
Dwell time Extrapolation factor
Figure 2. Ambient E-field values recorded outside the bridge – maximum frequency 200 MHz
250 ms 0 dB Figure 3. Ambient E-field values recorded outside the bridge – maximum frequency 2000 MHz
For the selected area outside the bridge, there was further measured the electric field strength during the transmission of a communication station - 100W, AM signal, frequency = 140MHz and 240 MHz, respectively. Field values are illustrated in Figs. 4 and 5.
Figure 7. Ambient E-field values recorded inside the bridge – maximum frequency 2000 MHz
Figure 4. E-field values outside the bridge – max. freq. 200 MHz, operating communication station 140MHz, AM, 100W
Figure 8. E-field values inside the bridge – max. freq. 200 MHz, operating communication station 140MHz, AM, 100W
Figure 5. E-field values outside the bridge – max. freq. 2000 MHz, operating communication station 240MHz, AM, 100W
Figure 9. E-field values inside the bridge – max. freq. 2000 MHz, operating communication station 240MHz, AM, 100W
Figure 6. Ambient E-field values recorded inside the bridge – maximum frequency 200 MHz
The measurements performed inside the bridge are represented in Figs. 6 and 7 – for ambient field values, whereas in Figs. 8 and 9 there are illustrated the field values during the transmission of a communication station - 100W, AM signal, frequency = 140MHz and 240 MHz, respectively.
Figure 10. Ambient E-field values recorded on the heliport deck – maximum frequency 200 MHz
Figure 13. E-field values on the heliport deck – max. freq. 2000 MHz, operating communication station 240MHz, AM, 100W
V.
RESULTS DISCUSSION
For the analyzed frequency ranges, the actions levels regarding the electric field strength in controlled environments imposed by European regulations [11] are: -
E= 61 V/m for frequency f = 100 MHz and
-
E= 131 V/m for frequency f = 1900 MHz, respectively.
If the analyzed areas are considered uncontrolled environments, the general public exposure has the following field limits [12]:
Figure 11. Ambient E-field values recorded on the heliport deck – maximum frequency 2000 MHz
-
E= 28 V/m for frequency f = 100 MHz and
-
E= 59 V/m for frequency f = 1900 MHz, respectively.
Personnel exposure to ambient field is not considered dangerous in the analyzed areas. Highest values were recorded outside the bridge, reaching a maximum value of E= 0.38 V/m for f = 104 MHz. For frequencies near 2 GHz, the maximum field value is E= 0.28 V/m. Inside the bridge the field is at its lowest, below 0.1 V/m in both frequency ranges. For heliport deck measurements, the maximum field value is E= 0.12 V/m for f = 1939 MHz. This is significantly lower compared to values measured outside the bridge, but higher than those measured inside the bridge. Fig. 14 describes the maximum ambient field values recorded in each area.
Figure 12. E-field values on the heliport deck – max. freq. 200 MHz, operating communication station 140MHz, AM, 100W
Finally, ambient field measurements illustrated in Figs. 10 and 11 were recorded on the heliport deck, located in the rear part of the ship. In the respective area, there were recorded the field values during the transmission of a communication station - 100W, AM signal, frequency = 140MHz and 240 MHz, respectively. Figure 14. Maximum E-field values (ambient) recorded in analyzed areas
Figure 15. Maximum E-field values recorded in the analyzed areas, during the transmission of a communication station
Figure 17. Maximum E-field values inside the bridge, measured as ambient field and during the station transmission, measured in two frequency ranges: 80-200 MHz and 200-2200 MHz, respectively
Thus there is noticed than the area inside the bridge is less exposed than the outside areas. The outside bridge is the most exposed area, due to short distance from antenna placement. Fig. 15 illustrates the maximum field values recorded in the analyzed areas, during the operation of a communication station. There is noticed a significant increase in the maximum field value recorded outside the bridge, E= 1.65 V/m for f = 140 MHz. Maximum field values registered an increase during the emission of the communication station, in all analyzed area, although not as high compared to the increase mentioned above. Figs. 16, 17 and 18 present the corresponding increase in maximum field value, in both frequency ranges. Thus, Fig. 16 describes the maximum field value recorded outside the bridge, and the corresponding frequencies. In the frequency range 80-200 MHz, the maximum field values were recorded for 104MHz – the ambient field, and for 140 MHz – during the station transmission. The increase is significant for the first frequency range. For the second one (200-2200 MHz), the maximum field value is approximately constant.
Figure 18. Maximum E-field values outside the bridge, measured as ambient field and during the station transmission, measured in two frequency ranges: 80-200 MHz and 200-2200 MHz, respectively
Figs. 17 and 18 indicate an increase in the maximum recorded field value, in both frequency ranges, but the increase is not a spectacular as in Fig. 16. This is probably due to the distance from the transmitting antenna. Even though the emitting communication antenna determined the increase of the electric field values, there final values are lower than standard imposed limits. VI.
Figure 16. Maximum E-field values outside the bridge, measured as ambient field and during the station transmission, measured in two frequency ranges: 80-200 MHz and 200-2200 MHz, respectively
CONCLUSIONS
Performed measurements describe the electromagnetic field on three locations: inside the bridge, outside the bridge and in the rear part of the ship, on the heliport deck. In order to detect the impact of one emitting communication station, first stage measurements recorded the ambient field on the considered areas. Then there were recorded the field values during the transmission of the considered communication station. All measurements were performed in two frequency ranges: 80200 MHz and 200-2200 MHz, respectively. The transmission of the communication station determined a higher radiation field, the highest increase being detected outside the bridge. The resulting field is still lower, compared to the standard imposed limits.
Though measurements did not indicate field levels higher than the standard limits, protective measures are indicated for personnel working near radar and communications antennas, and further measurements need to be performed. When the ship is navigating, all communication and radar antennas are transmitting, and the radiation field is probably higher.
[7]
REFERENCES
[10]
[1]
[2]
[3] [4]
[5] [6]
Zamfirescu, M., Sajin, I., Rusu, I., Sajin, M., Kovacs, E., “Efecte biologice ale radiaţiilor electromagnetice de radiofrecvenţă şi microunde” (The biological effects of radiofrequency and microwave electromagnetic radiations), Medical, Bucharest, 2000 M. Ianoz, A review of studies on Health Effects of Electromagnetic Fields, ICPE-CA 9th Electromagnetic Compatibility Workshop, Sibiu, Romania, 2012 I.A. Holodov, Magnetism in biology, Scientific Publishing House, 1974 C. Gary, The biological effects of magnetic fields from the electrical engineer standpoint (in Romanian and French), in Energetica, 41, no.2B, 1993, pp. 56-68 Carlo Kopp, “The Electromagnetic Bomb, Weapon of Electronic Mass Destruction”, RAAF Air Power Studies Center, USA, 1996. ***, “Portable EMF Measurement System, User Manual, Rohde & Schwarz, Germany, 2006.
[8]
[9]
[11] [12]
[13] [14] [15]
ECC RECOMMENDATION (02)04 revised, Measuring non-ionising electromagnetic radiation (9 kHz – 300 GHz), October 2003. S. Miclaus, P. Bechet, Estimated and Measured Values of the Radiofrequency Radiation Power Density around Cellular Base Stations, Rom. Journ. Phys., vol. 52, nos.3-4, pp. 429-440, Bucharest, 2007. Byung Chan Kim, Two Different Techniques for Evaluating Electromagnetic Fields Radiated from Radio Base Stations in Korea,Conference EMC 09, Kyoto,2009, pp. 497-500. Baste V, Mild KH, Moen BE. Radiofrequency exposure on fast patrol boats in the Royal Norwegian Navy--an approach to a dose assessment, Bioelectromagnetics. 31(5):350-360, 2010. ***Directive 2013/35/EU of the European Parliament and of the Council of 26 June 2013 ***Council Recommendation of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz), 1999/519/EC ***OMSF 1193/29.09.2006, Official Romanian Gazette 895/03.11.2006 ***HG 1136/30.08.2006, Official Romanian Gazette 769/11.09.2006 NATO Standard – “Evaluation and Control of Personnel Exposure To Radio Frequency Fields – 3 KHz to 300 GHz”, 13 febr.2003
