Radiation Hazard Aspect of Shipboard Radiocommunication Equipment

Transcription

1 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE Radiation Hazard Aspect of Shipboard Radiocounication Equipent Antonio Šarolić and Borivoj Modlic Original scientific paper Abstract: The paper analyzes the electroagnetic (EM) radiofrequency (RF) radiation hazards onboard a ship arising fro shipboard radiocounication and navigation equipent EM field effect on personnel and equipent can be harful if field levels exceed the threshold values These fields need to be controlled for proper protection Ships are equipped with lots of EM RF radiation sources with different frequencies and output power levels Typical shipboard EM RF radiation sources include: terrestrial radiocounication transitters, navigational radars and satellite ship earth stations (SES) Exaples of these sources are analyzed in the paper EM field estiation using siple worst-case calculation is given for a typical HF transitter, X-band navigational radar and the Inarsat SES A, B, C, F and M The estiation probles are discussed The calculation results are copared with international civil and ilitary standards The results show that potential hazards exist and that a reasonable aount of caution is needed Index ters: radiocounications, shipboard radiation hazard, navigation I INTRODUCTION Electroagnetic (EM) field effect on personnel and equipent can be harful if field level exceeds the detriental effect threshold value Exposure liits are prescribed in relevant docuents [1-3] and are acknowledged internationally Liits are frequency-dependant, expressed separately in ters of electric field strength, agnetic field strength and power density Above 10 MHz, the quantities can be used interchangeably, ie the EM field can be defined with only one quantity Thus the power density is ainly used for describing liits in radiofrequency (RF) range which is of interest for shipboard counication and navigation equipent Ships are equipped with lots of EM radiation sources with different frequencies and output power levels The crew and equipent are exposed to EM radiation and this exposure needs to be controlled for protection The confined space of a ship akes the proble even bigger The crew is bound to occupy spaces in the vicinity of EM sources Also, the nuber of sources is large Modern aritie transport safety is based on radiocounications, both for counication itself and also for navigation, therefore there is a variety of RF equipent installed onboard Manuscript received May 11, 006 and revised June 0, 007 A Šarolić is with the University of Split, Faculty of Electotehnical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia (e-ail: antoniosarolic@fesbhr) B Modlic is with the University of Zagreb, Faculty of Electotehnical Engineering and Coputing, Zagreb, Croatia (e-ail: borivojodlic@ferhr) The subject of huan EM field exposure and protection is becoing ore and ore regulated However, aritie applications of RF equipent are still not fully and thoroughly covered regarding this subject For exaple, one of the basic standards on aritie navigation and radiocounication equipent and systes [4], issued by IEC TC 80 [7-8], [1], includes a provision that: - EM RF radiating equipent above 30 MHz shall be subjected to easureents to deterine the level of such radiated energy; - resulting fro such easureents, the axiu distance fro the equipent at which the power density level of 100 W/ and 10 W/ has been easured shall be included in the equipent anual The principle of this clause does not fully coply with widely accepted docuents [1] and [], regarding its liited frequency scope and liit that is not frequency-dependant Therefore there is a need to analyze soe typical shipboard exposure situations according to [1] and [] This paper analyzes soe specific but typical EM field sources widely used aboard ships: terrestrial counication transitter, satellite counication transitter and navigational radar Relevant shipboard EM field levels were estiated The levels were copared to the standards that define axiu peritted exposure liits (PEL) of electric (E) and agnetic (H) field at the specific frequency, considering all exposure conditions II TYPICAL SHIPBOARD EM FIELD SOURCES A Terrestrial counication transitter Modern ships are coonly equipped with various transitters for terrestrial counications Depending on the navigation area, different frequency ranges are used: MF, HF or VHF For coastal navigation, VHF transitters are the ost coon ones However, their output power is uch lower than the power of MF and HF transitters, and as such is less interesting for this analysis MF transitters are used rarely aboard ships in the coastal navigation Thus, in this paper, an HF transitter is analyzed It is in fact an AM SSB radio that operates in the HF band (3 30 MHz) The shipboard EM field levels originating fro this source were estiated assuing it is placed onboard a 50 steel ship The levels were copared to the standards that define perissible exposure liits (PELs) of electric and agnetic field at the specific frequency, considering all exposure conditions /07/ CCIS

2 41 14 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE 007 B Navigational radar The navigational radar is an iportant EM field source since it is a standard piece of equipent which uses a high output power Navigational radars operate either in the S band (around 3 GHz) or in the X band (around 94 GHz) In this paper, an X-band radar is analyzed The shipboard EM field levels originating fro this source were estiated assuing it is placed onboard a 50 steel ship The levels were copared to the standards that define perissible exposure liits (PELs) of electric and agnetic field at the specific frequency, considering all exposure conditions Besides these exposure conditions, the radiation hazard aspect of an X-band radar aboard a sall ship (eg recreational boat) was specifically analyzed On sall ships, the close proxiity of the radar antenna to the crew, and also the sall or no elevation at all fro the antenna to the crew, ake this situation a possible threat The analytic calculation of the electroagnetic power density should enable the coparison of the exposure situation to the relevant huan exposure protection guidelines considered here Mainlobe direction is horizontal Antenna gain is about 075 The source is turned on occasionally for short eissions and then operates with full power, if properly atched Fig 1 Topside geoetry of a ediu size (50 ) ship C Satellite counication transitter Besides previously entioned shipboard radiation hazards, there is a need to analyze potential radiation hazards arising fro ship earth stations (SES) for satellite counications Satellite counications usage grows along with the need for new and ore advanced services besides analog voice counications and facsiile Digital data counications are essential for odern fleet anageent Internet access is now coon also on leisure vessels All this leads to wider use of SES equipent, even on sall boats with space constraints regarding equipent installation The shipboard satellite counications ostly rely on the Inarsat syste, thus, in this paper, the Inarsat SES is analyzed Coon shipboard satellite counication installations and their ability to irradiate the crew are reviewed The shipboard EM field levels originating fro several kinds of Inarsat SES were estiated A HF transitter III SOURCE CHARACTERISTICS The HF electroagnetic radiation source is in fact a single side band (SSB) aplitude-odulated (AM) radio transitter, located onboard a ediu size steel-built ship It works in the HF frequency band, with the peak envelope power (PEP) of 100 W This analysis and easureents were done at the frequency of 10 MHz It uses the four-segented 6 long whip antenna located on the ship topside as seen on Fig1 The antenna is electrically short, autoatically tuned to the transitter at the appropriate frequency by a atching network When tuned, it radiates 100 W of PEP in the AM SSB ode Its radiation pattern is alost isotropic in the horizontal plane and half-ofeight figured in the vertical plane Both radiation patterns can be defored by ship superstructure, but this effect will not be B X-band navigational radar The radar antenna diensions typically range fro 05 to 4, depending on the size of the ship and output power (which also affects the range) The S-band antennas are larger, because the wanted antenna characteristics ust be obtained on the longer wavelength Antenna rotates, with typically about 5 rounds per inute, to scan the entire horizon for targets and obstacles The wanted antenna characteristics are the following: about 1º horizontal beawidth, needed to obtain high aziuthal resolution; about 5º vertical beawidth, needed to ensure that the ainbea points to horizon even on rough sea, when ship rolls Typical antenna gain is around 30 db The navigational radar radiation is pulse odulated The order of agnitude of the peak output power (during a pulse) is 10 kw Values range fro kw to 50 kw, with typical values of 0 kw for larger ships and 5 kw for sall ships The first navigational radar considered was a specific radar located onboard the sae ediu size steel-built ship as the previously entioned HF transitter It uses the Kelvin- Hughes slot array antenna located on the ship topside as seen in Fig1 The radar works in the X band at 94 GHz in pulse ode Peak output power (in the duration of a pulse) is 0 kw, which is coon output power of shipboard radars The average power depends on the duty cycle, which in turn depends on the radar distance range The radar uses the axiu power when working in the short distance range, with the pulse duration of T p = 05 µs and repetition frequency f r = 1700 Hz The antenna ainlobe characteristics are 1º horizontal beawidth and 0º vertical beawidth The antenna is 1 wide, located about half-way fro bow to stern, 8 high above the deck, as shown in Fig1 and it rotates with 3 rp

3 ŠAROLIĆ AND MODLIC: RADIATION HAZARD ASPECT OF SHIPBOARD RADIOCOMMUNICATION EQUIPMENT The radar is turned on continuously when ship is out of the port The second case considered is a non-specific typical navigational radar on a recreational boat A otor boat with the anufacturer specifications and diensions was randoly chosen The sideview is given in Fig The antenna position is also suggested by anufacturer The picture also shows the ainlobe of the radar radiation The antenna is usually ounted on the highest place above deck to avoid obstructions of line-of-sight direction, as in Fig4 A casual thought of the antenna in the highest place, pointed skywards, would lead to the false conclusion that there is no possibility of radiation hazard to the crew HORIZON 5O 117 Fig Geoetry of the exposure situation Fig 4 Inarsat antenna installed on the highest topside construction Fig 3 Radar ounted on a recreational otor boat One can see that the people on the top deck (fly bridge) in Fig3 are ost certainly exposed to the ain bea of radiation The distance fro the antenna on the saller ships can be as short as 1 Fig 5 Inarsat antenna installed on the deck C Inarsat SES Most Inarsat SES use a surface antenna pointed to the satellite The tracking echanis ensures the right direction to the satellite, even in conditions of ship rolling sideways ±5º The surface antenna (parabolic reflector or planar array) is oving inside a stationary radoe that provides an environental enclosure (see figures) Inarsat C usually uses stationary lower gain antenna that is heispherically onidirectional and cover the whole elevation span at once In this paper, the ephasis is on the analysis of the high gain aperture antennas However, there are situations in which the antenna is ounted right on the deck (sail boats and other sall boats), as in Fig5 and Fig6 Cases are even reported where antenna is ounted below deck, provided that the deck is nonconductive Also, the antenna is not always pointed skywards with high elevation The needed elevation is the result of the SES position relative to the Inarsat satellite This relative position depends on the SES latitude and longitude, and at soe geographical locations the antenna elevation can be very low Due to this fact and also due to ship rolling (see Fig6), the Inarsat antenna specifications deand that the antenna

4 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE 007 elevation inside the radoe can be anything fro -5º to 90º It is now obvious that there are situations when the crew can be unawarely exposed to the ain bea of the Inarsat SES value obtained by spatial averaging over an area equivalent to the vertical cross-section (projected area) of the huan body In nonunifor fields, peak values could exceed the PELs even though the averaged value does not exceed the PEL However, peak field strength is also liited The peak perissible liit in ters of power density is given as 1000 larger value than the PEL itself at the specific frequency, for frequencies exceeding 10 MHz B Fire & Explosion Hazards (HERF and HERO) Fig 6 Inarsat antenna installed on the deck, ship rolling sideways by ca 5º IV RADIATION HAZARD REGULATIONS The objective of this analysis is to deterine the axiu distance beyond which there is no danger of EM field overexposure Two types of hazards can be distinguished: biological hazards and fire/explosion hazards The biological hazards are soeties referred to as Hazards of Electroagnetic Radiation to Personnel (HERP), especially in ilitary terinology Fire and explosion hazards are referred to as Hazards of Electroagnetic Radiation to Ordnance (HERO) and Fuel (HERF) Standard [1] is used for HERP PELs US Navy Instruction [3] is used for HERO and HERF PELs A Biological Hazards (HERP) While there is a lack of inforation on biological effects of EM fields, still there is enough of it to produce regulations, so any countries already issued their standards They depend on research conducted in the specific country, and that is the reason for differences between the Considering that the effects are equal anywhere in the world, there is a need to integrate standards into one EMF exposure is priarily classified to professional exposure in the workplace and uncontrolled exposure of people not aware of the danger The US standard [] uses the ters controlled environent exposure and uncontrolled environent exposure while ICNIRP [1] uses the ters occupational exposure and public exposure Controlled environent refers to the areas with personnel accepting the exposure as a part of their workplace, aware of the potential danger and constantly (or periodically) subjected to health exainations, as well as protection easures Uncontrolled environent refers to all other exposure conditions and groups of people Therefore, it is necessary to define ore restrictive standards for this type of exposure PEL (Perissible Exposure Liit) is tie-averaged exposure According to [3], there are three HERO categories regarding EM radiation sensitivity The HERO liit refers to unreliable devices with exposed wires arranged in ost susceptible receiving orientation, ostly during assebly/disassebly of ordnance, but also applies to untested ordnance until proven safe HERO liit 1 applies to the less sensitive ordnance There is also the third class of ordnance which is totally insensitive to EMF and there are no exposure liits for this class It is necessary to classify the ordnance into one of these categories which is already done in the US Ary US Navy instruction [3] specifies HERO RADHAZ levels at frequencies below 1 GHz in ters of peak value of electric field strength, while levels above 00 MHz are specified in average power density The potential danger to ordnance is obvious so these liits are generally lower than personnel liits These are soe general guidelines to avoid HERF [3]: Do not energize a transitter (radar/co) on an aircraft or otor vehicle being fueled or on an adjacent aircraft or vehicle Do not ake or break any electrical or ground wire, or tie down connector while fueling Radars capable of illuinating fueling areas with peak power density of 5 W/c should be shut off For shore stations, antennas radiating 50 W or less should be installed at least 15 (50 ft) fro fueling areas For antennas which radiate ore than 50 W, the power density at 15 (50 ft) fro the fueling operation should not be greater than the equivalent power density of a 50 W transitter located at 15 (50 ft) distance V RADIATION HAZARD ESTIMATION A HF transitter For the ainlobe direction and the far-field region, power density S is calculated by: S= P G 4R π (1) where P is the ean output power, G is gain, R is distance fro antenna For linear antenna, this relation can be used also in the near-field region, yielding the worst-case overestiation

5 ŠAROLIĆ AND MODLIC: RADIATION HAZARD ASPECT OF SHIPBOARD RADIOCOMMUNICATION EQUIPMENT EMF estiation proble exists because antennas are priarily used to radiate in the far field (Fraunhofer region), and exposure usually takes place in the near field Thus, anufacturer antenna specifications refer to the far field and are not applicable to the specific exposure situation Fraunhofer approxiation siplifies field calculations assuing the source is far enough to be treated as a point source R99 is the distance fro antenna where the actual field equals 99% of the field calculated with the Fraunhofer approxiation That distance is considered the near-field to far-field boundary and is calculated by well known equation: R99 = D λ () where D is the largest antenna diension and λ is wavelength Below the R99 boundary the field strength oscillates with the distance The radiation pattern in the near field is generally different fro that of the far field and phase oscillations in the near field decrease the antenna gain in the ain lobe direction The near-field diagra for linear antenna according to [16] is shown in Fig7 Power density is noralized to unity (0dB) at R99, which is the point with power density arked as S99 The Y axis values are not arked because they differ fro one antenna to another, depending on the current distribution cause reflections (object diensions greater than λ) or scattering (object diensions less than λ) For these reasons, field strength can be increased by superposition Superposition, ie constructive interference can double the field strength, although [5] suggests ore realistic increase factor of 16 for the field strength or 16 = 56 for the power density Equation (1) then changes to: S= 56 P G 064 P G = 4 R π R π (4) Thus, PEL accoplishing distance (designated with RPEL) could be calculated by: RPEL = 064 P G πs PEL (5) Since P is the ean transitted power, it ust be related to the specified peak envelope power (PEP) of the transitter For audio signals, PEP is related to the ean power as: P= PEP 10 (6) and the following equation is obtained: RPEL = 064 PEP G 10π S PEL (7) When radiation hazard estiation is based on peak liit SPELpeak, the peak PEL accoplishing distance RPELpeak will be calculated using peak power (PEP) by: RPELpeak = Fig 7 Power density in the ainlobe direction for linear antenna Thus, PEL accoplishing distance (designated with RPEL) can be calculated by: RPEL = P G 4πS PEL (3) where SPEL is PEL in ters of equivalent plane wave current density However, in the reflective environent such as ship deck, reflections and diffraction additionally coplicate the field estiation and can cause unexpected field levels There are any etal parts onboard a ship in the radiation region They 0,64 PEP G πs PELpeak (8) B X-band navigational radar on a large ship For the ainlobe direction and the far field region, equations (1) and () apply as given for the HF transitter Correction due to reflections ust be carefully observed here Huan radiation hazard is estiated in two separate ways: using the field averaged over a huan body diensions, and using the peak field strength Considering the wavelength, the body diensions would average the constructive and destructive interferences, so the correction is not needed for average field However, if the peak field strength value or the value in only one point is needed (eg for HERO), possible constructive interference should be taken into account as in (3) and (4) Power density averaging due to pulse ode decreases the radiated power by duty cycle (pulse period/repetition period ratio) TP/TR The antenna rotation causes further decrease by

6 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE 007 exposure tie/rotating tie ratio T E /T ROT Relations () and (4) transfor to relations (7) and (8): When HERP estiation is based on peak liit S PELpeak, the peak PEL accoplishing distance R PELpeak will be calculated without tie averaging, using the following equation: R PEL P G TP T = 4πS T T E PEL R ROT (9) R PELpeak = 064 P G πs PELpeak (11) R PEL = 064 P G T πs T PEL P R T T E ROT (10) HERO estiation is based on average field strength at one point in space, so equation (10) is used In the shortest distance range operating ode, duty cycle T P /T R equals Because of the sidelobe suppression, in this consideration it can be assued that the whole energy is concentrated in the ainlobe, and there is no radiation during the rest of the rotation period, so T E /T ROT equals 1/360 The observed antenna nuerical gain is 1718 The question is what the real R PEL is for the particular exposure situation because relation (1) applies only to radiating field and the ainlobe direction Thus, this equation is valid only in the far-field region or for worst-case analysis, so the far-field condition ust be checked according to () Calculated distance R 99 is about 90 for the antenna diension of 1 This eans that the ship deck is exposed in the near-field region, and equation (1) can serve only as the worst-case analysis More accurate analysis cannot be done this siply In the near-field region, field can never reach the level greater than calculated here, even in the ainlobe direction, and, because of the antenna height, there is usually no personnel in the ainlobe direction R PEL calculated by relations (7) and (8) can be assued to present the safe liit beyond which field greater than PEL cannot occur, for the observed single source The near-field diagra for surface antenna according to [16] is shown in Fig8 Power density is noralized to unity (0dB) at R 99, which is the point with power density arked as S 99 The Y axis values are not arked because they differ fro one antenna to another, depending on the current distribution The power density oscillates with the distance, but in different way than for linear antennas (Fig7) C X-band navigational radar on a sall ship The electroagnetic power density will again be calculated using analytical equation (1) Since these kinds of ships are ade ainly of fiberglass, it can be assued that there are no reflections that could further increase the power density The question of concern is to find if the top deck (fly bridge) is inside the area exposed to power density above PEL The distance R PEL will be calculated using (9) with all the typical values for sall ship radars entioned earlier, with T P /T R ratio of 1/1000 Calculated distance R 99 is about 0 for the antenna diension of 06 When radiation hazard estiation is based on peak liit S PELpeak, the peak PEL accoplishing distance R PELpeak will be calculated without tie averaging, using R PELpeak and S PELpeak in equation (3) HERO will not be estiated for a sall ship (recreational boat) D Inarsat SES The radiation hazard will be estiated by coparing the calculated power density around the antenna to the perissible exposure liit (PEL) for general public, as given in [1] This paper gives the analysis of high gain antennas with suppressed sidelobes (by ca 5dB) The ainlobe is a pencil bea directed to the satellite Accordingly, only the power density inside the ainlobe will be calculated since the exposure to the ain bea is the worst case that can happen in this analysis The constructive interference fro reflections cannot occur For the worst case analysis, following assuptions are ade: continuous axiu transitted power as defined in specifications for every Inarsat service analyzed (Table I); continuous exposure that takes place inside the ainlobe TABLE I MAXIMUM PERMITTED EIRP AND TYPICAL ANTENNA DIAMETERS FOR VARIOUS INMARSAT SES Fig 8 Power density in the ainlobe direction for surface antenna Inarsat A B C M F Max EIRP, dbw D,

7 ŠAROLIĆ AND MODLIC: RADIATION HAZARD ASPECT OF SHIPBOARD RADIOCOMMUNICATION EQUIPMENT The power density calculated using the far-field equation (1) presents the top liit of possible power density around the antenna Using this equation in the near field leads to overestiation of the exposure Using the following equations based on epirical odel for circular surface antennas [5], the near-field region and transition region power density values can be observed quite accurately The reactive near-field and far-field boundaries for such antenna are given by: Rnf = D, 4λ Rff = 06 D λ (1) where Rnf is the reactive near-field boundary, Rff is the farfield boundary, λ is the wavelength (ca 018 for Inarsat uplink frequency) and D is the antenna diaeter Typical antennas diaeters are given in Table I The axiu power density at the antenna surface Ssurf can be approxiated by: Ssurf = 4P A (13) where P is the TX power and A is the physical area of the aperture antenna The axiu power density in the reactive near-field or Fresnel region Snf can be calculated by: Doing this analysis using just general Inarsat and SES anufacturer specifications, two paraeters usually lack: the antenna power gain G and the TX power P The gain can be calculated by equation (6) using the assued efficiency of η = 065, and the TX power can be calculated fro gain and specified EIRP: G= 4 πη A, λ P= EIRP G (18) Specifically for Inarsat C, antenna can be any type of stationary antenna (printed antenna, helicoidal antenna etc) so equations (1) to (6) do not copletely apply, and only the farfield values using equation (5) will be calculated Also, the far-field boundary, Rff is given by ore general equation () where Rff equals R99 VI HAZARD ESTIMATION A HF transitter PELs and PEL accoplishing liits are given in following Tables TABLE II PELS FOR HF TRANSMITTER Snf = 16η P πd (14) where η is the aperture efficiency The aperture efficiency is typically for circular surface antennas [5] A value of η = 065 is assued here The axiu power density in the radiating near-field or transition region (the space between the reactive near-field and far-field boundaries) Strans can be calculated by: Strans = Snf Rnf R (15) where R is the distance to the area of interest At the distance greater than Rff, ie in the far-field region, the power density can be calculated by: S= EIRP 4Rπ (16) where EIRP = P G (17) At the distance R = Rff, equations (15) and (16) should give alost the sae result arked as Sff The PEL accoplishing distance RPEL can be calculated fro equation (16) if PEL [1] in ters of power density, SPEL, is used Frequency: 10 MHz W/ HERP S PEL 10 W/ 3 10 W/ HERP S PELpeak W/ Liit 1 00 W/ HERO S PELpeak -4 Liit 10 W/ For frequencies exceeding 10 MHz, HERP peak liit [1] is given as: S PELpeak = S PEL 1000 (19) TABLE III PEL ACCOMPL DISTANCES FOR HF TRANSMITTER HF SSB transitter, PEP = 100 W 0,9 0,4 0,1 peak 0,0 Liit 1 7,6 peak Liit 390,9

8 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE 007 B Navigational radar C Inarsat SES PELs and PEL accoplishing distances are given in following Tables Equation (19) applies TABLE IV PELS FOR NAVIGATIONAL RADAR Frequency: 94 GHz 10 W/ HERP S PEL 50 W/ W/ HERP S PELpeak W/ Liit 1 40 W/ HERO S PEL Liit 0 W/ Table IV shows that the HERP and HERO liits given in ter of average power strength are very siilar, being of the sae order of agnitude However, the peak liit is three orders of agnitude higher This could indicate that this liit is less stringent On the contrary, PEL accoplishing distance is uch larger for peak PEL, as can be seen in Tables V and VI This eans that greater area is endangered with peak PEL than with average PEL The reason is obviously in tie averaging schee described in equations (9), (10) and (11) The tie averaged power density originating fro radar decreases 5 to 6 orders of agnitude, while the peak liit is only 3 orders of agnitude higher TABLE V PEL ACCOMPL DISTANCES FOR NAVIGATIONAL RADAR ON A LARGE SHIP Nav radar on large ship, P = 0 kw 0,6 0,3 6,5 peak 11,8 Liit 1 0,5 Liit 0,7 TABLE VI PEL ACCOMPL DISTANCES FOR NAVIGATIONAL RADAR ON A SMALL SHIP Nav radar on sall ship, P = 5 kw 0,3 0,1 6,3 peak,8 PELs and PEL accoplishing liits are given in following Tables Equation (19) applies, but since the continuous radiation is assued, r PELpeak need not be checked TABLE VII PELS FOR INMARSAT SES Frequency: 16 GHz 8 W/ HERP S PEL 40 W/ W/ HERP S PELpeak W/ Liit 1 W/ HERO S PELpeak Liit 1 W/ HERP PEL is given in ters of power density spatially averaged over the entire body and tie averaged over any 6 inutes of exposure [1] If the exposure is only partial (libs, other body parts), values greater than PEL are peritted by [1], but not for eyes and testes [] This deserves further coent Since aperture antennas tend to produce pencil bea of radiation, the fored ainlobe is narrow and it cannot irradiate the whole huan body, so exposure to the fored bea in the vicinity of the antenna is alost certainly partial Non-continuous exposures, shorter than 6 inutes, especially of libs, would not be so harful even at the shorter distances to the antenna On the other hand, the harful exposure takes place in the near-field (transition region) where the narrow bea has not yet been fored, so the exposed area of the body is not so sall Considering also the protection of eyes and testes, the use of the whole body PEL is justified for the worst case analysis TABLE VIII NEAR-FIELD POWER DENSITY OF INMARSAT SES Inarsat A B C M F R nf, R ff, S surf, W/ S nf, W/ S ff, W/ R PEL, Calculation results in Table VIII show that the exposure is ostly above PEL throughout the near-field region The power density at the antenna surface (at the radoe) and in the transition region is uch higher than PEL Although huan exposure in the reactive near-field cannot be well analyzed by analytical equations, it is alost certain that this exposure is harful

9 ŠAROLIĆ AND MODLIC: RADIATION HAZARD ASPECT OF SHIPBOARD RADIOCOMMUNICATION EQUIPMENT TABLE IX PEL ACCOMPL DISTANCES FOR INMARSAT SES Inarsat A SES Liit 1 Liit 5,6,5,8 4,0 Inarsat B SES Liit 1 Liit 4,0 1,8,0,8 Inarsat C SES Liit 1 Liit 0,6 0,3 0,3 0,4 Inarsat M SES Liit 1 Liit,0 0,9 1,0 1,4 Inarsat F SES Liit 1 Liit 3,6 1,6 1,8,5 VII CONCLUSIONS The conclusions are presented separately for each type of analyzed sources 1 The analysis of the HF transitter field levels shows that fields on the deck are under HERP PELs The potential danger is still lowered because radio is used ainly for short duration transissions, while HERP PEL refers to the 6 in average level, as defined by [1] Nevertheless, these fields cannot be disregarded in the iediate vicinity of the antenna Also, HERO and HERF unsafe distances ay encopass fueling areas and ordnance assebly/disassebly areas Hazards are real and should be avoided by protective easures The navigational radar electric field on the deck of a large ship was well under HERP and HERO PELs Although the safe distance for HERP peak PEL is uch larger than for averaged PEL, the deck can be considered safe since the antenna is positioned quite high on the ship superstructure and the ain bea overshoots the deck This kind of installation can be considered hazard-free according to the present HERP and HERO recoendations HERF recoendations [3] show that the radiation of navigational radar ay encopass fueling areas, potentially causing fuel ignition Hazards are real and should be avoided by protective easures, especially by eission control 3 The results of the analysis of a navigational radar on a sall ship show that the analyzed situation does not copletely coply with the relevant huan protection guidelines, regarding the top deck (fly bridge) exposure to peak field values above the liit for peak HERP PEL There is certainly a need for caution in approach to the navigational radar antenna installation Considering the liited diensions of a sall ship, extending the antenna distance fro the crew is not possible Nevertheless, raising the height of the antenna should solve this proble without the need for further adjustents 4 The analysis of the radiation hazard of shipboard Inarsat SES refers to the worst case: whole body or sensitive body parts exposure, exposure to the ain bea of radiation, exposure longer than 6 inutes The analysis shows that the exposure to typical Inarsat SES could be harful in the ain bea, at the distances within few eters fro the transitting antenna Since the direction of the ain bea is not observable to the crew, approach to the iediate vicinity of the antenna should be restricted at the calculated distances The conclusions of the analysis presented in this paper encourage further research of different exposure configurations REFERENCES [1] International Nonionizing Radiation Coittee of the International Radiation Protection Association, "Guidelines for Liiting Exposure to Tie-Varying Electric, Magnetic, and Electroagnetic Fields (up to 300 Ghz)", Health Phys, Vol 74, 4, (1998) pp [] IEEE C : IEEE Standard for Safety Levels with Respect to Huan Exposure to Radio Frequency Electroagnetic Fields, 3kHz to 300GHz, Institute of Electrical and Electronics Engineers (IEEE), New York, 1991 [3] US Navy regulation NAVSEA OP3565/ NAVAIR "Electroagnetic Radiation Hazards", ( radhazpdf) [4] EN 60945:00 Maritie navigation and radiocounication equipent and systes - General requireents - Methods of testing and required test results (IEC 60945:00) [5] OET Bulletin 65: Evaluating Copliance with FCC Guidelines for Huan Exposure to Radiofrequency Electroagnetic Fields, Federal Counications Coission (FCC), Washington, 1997 [6] M Vujić, A Šarolić, B Modlic, " Shipboard Radiation Hazards INMARSAT Ship Earth Station", 47th International Syposiu Electronics in Marine, Zadar, Croatia, June 005, pp [7] A Šarolić, "A Review of Maritie Navigation and Radiocounication Equipent and Systes Standardization", 46th International Syposiu Electronics in Marine, Zadar, Croatia, June 004, pp [8] A Šarolić, "E TO 80 Standardization Activities First Phase Finished", 44th International Syposiu Electronics in Marine ELMAR 00, Zadar, Croatia, June 00, pp83-87 [9] A Šarolić, D Poljak, B Modlic, "Navigational Radar Radiation Hazard Analysis for Sall Ships", 44th International Syposiu Electronics in Marine, Zadar, Croatia, June 00, pp 78-8 [10] A Šarolić, B Modlic, V Roje, D Poljak, P Pavić, "Shipboard

10 40 13 [11] [1] [13] [14] [15] [16] [17] [18] JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL 3, NO, JUNE 007 RF equipent radiation easureents and hazard analysis", EMC EUROPE 00 International Syposiu on Electroagnetic Copatibility, Volue II, Sorrento, Italy, Septeber 00, pp A Šarolić, B Modlic, K Malarić, "Shipboard HF electroagnetic field easureents for EMC", Proceedings of 11th IMEKO TC-4 Syposiu on Trends in Electrical Measureent and Instruentation, Lisboa, 001, pp38-4 A Šarolić, "National Technical Coittee for Maritie Navigation and Radiocounication Equipent and Systes Standardization Activities", 43rd International Syposiu Electronics in Marine ELMAR 001, Zadar, Croatia, June 001, pp1-4 A Šarolić, B Modlic, P Pavić, V Roje, D Poljak, "Harful Shipboard Electroagnetic Fields - Navigational Radar Measureents", 43rd International Syposiu Electronics in Marine, Zadar, Croatia, June 001, pp 5-9 A Šarolić, B Modlic, P Pavić, V Roje, D Poljak, "Harful Shipboard Electroagnetic Fields - HF Radio Transitter Measureents", 41st International Syposiu Proceedings Electronics in Marine, Zadar, Croatia, June 1999, pp P Pavić, A Šarolić, B Modlic, "Harful Electroagnetic Fields on Ships - Standards and Worst Case Estiation", 40th International Syposiu Proceedings Electronics in Marine, Zadar, Croatia, June 1998, pp Hansen, RC, Microwave Scanning Antennas, VolI, Acadeic Press, New York, 1964 International Maritie Organization, INMARSAT, Antonio Šarolić received the BS, MS and PhD degrees in Electrical Engineering in 1995, 000 and 004 fro the University of Zagreb, Croatia He had been eployed there fro 1995 to 005, at the Faculty of Electrical Engineering and Coputing (FER), Dept of Radiocounications In 006 he joined the University of Split, FESB, Departent of Electronics and is now Assistant Professor in Electrical Engineering His areas of interest are electroagnetic easureents, bioeffects of EM fields, electroagnetic copatibility (EMC) and radiocounications Dr Šarolić has been working on several research projects and has authored over 40 papers and nuerous technical expertises in previously naed topics He is also involved in standardization process through various coittees and working groups Borivoj Modlic received the BS, M S and PhD degrees in Electrical Engineering in 197, 1974 and 1976, respectively, fro the Faculty of Electrical Engineering, University of Zagreb, Croatia He is a Full Professor at the University of Zagreb, Faculty of Electrical Engineering and Coputing (FER), Dept of Wireless Counications Dr Modlic is coauthor of six university textbooks and editor of the Engineering Handbook His research interests are: signal processing in counications, especially odulation ethods, wireless access systes, electroagnetic copatibility and electroagnetic field ipacts on huan health as well as the related health hazards estiation