1. NPS RADIO FREQUENCY (RF) USER TRAINING

2. PURPOSE The purpose of this training is to provide you with the necessary knowledge needed for safe operation of RF emitting equipment utilized in support of research and training This training is required for all RFR System User’s in accordance with OPNAVINST 5100.23 CH.22, DoD Instruction 6055.11, ANSI/ IEEE C95.1/3,and NAVPGSCOLINST 6055.11

3. ACRONYM FAMILIARIZATION RF- Radio Frequency RFR- Radio Frequency Radiation EMF- Electro Magnetic Field PEL- Permissible Exposure Level MPE- Maximum Permissible Exposure SOP- Standard Operation Procedures PPE- Personal Protective Equipment TERP- Transmitted EMF Radiation Protection RFSO- Radio Frequency Safety Officer ARFSO- Assistant Radio Frequency Safety Officer DRS- Department Radio Frequency Safety Supervisor OTSG- Office of the Surgeon General dB- Decibel GHz- Gigahertz kHz- Kilohertz

4. OVERVIEW In this training you will focus on the following topics regarding Radio Frequency and Microwave Radiation: Module One - Electromagnetic and Radio Frequency (RF) Fundamentals Module Two - Potential Health Effects of RF Radiation Module Three - National, Navy, and NPS Standards and Limits for Use of RF Sources and Protection for Personnel Module Four - The Structure of the NPS RF Safety Program and how you interact with it Module Five - Standard Procedures, Controls, Warnings, and Signs Module Six - Limiting your exposure to RFR and Some Special Considerations Each of these training modules contains approximately 5-15 slides for a total length of approx 75 slides. The average user spends 60 minutes to take this training. There is a quiz which follows the training in order to achieve certification as an NPS Authorized Radiofrequency User (ARU) or an NPS RF PI (RPI). Additional information on the quiz is provided at the completion of the training.

5. Module One Electromagnetic and Radio Frequency (RF) Fundamentals

6. EM and RF Fundamentals A current flowing in a conductor gives rise to a magnetic field around it. When such a current is varying, it gives rise to a similarly changing electric field. Similarly a changing electric field will give rise to a magnetic field. Electromagnetic waves propagated in free space have the electric and magnetic fields perpendicular to each other and to the direction of propagation. These are known as transverse electromagnetic waves (TEM waves).

7. EM and RF Fundamentals A fundamental concept in EM theory is the idea of wave propagation c = Speed of Light in a Vacuum = 3 x 10 8 m/sec λ = Wavelength in m f = Frequency in Hz c = λf When frequency is known in MHz this equation can be rewritten to its more useful thumbrule form: λ = 300/f

8. Non Ionizing Radiation Frequency – Wavelength Relationships = Wavelength – 1 Hz = 3 x 10 8 meters – 60 Hz = 5 x 10 6 m Note that this is the approximate distance of the U.S. from the East to West Coast – 3 kHz = 100,000 m – 300 kHz = 1,000m – 1 MHz = 300 m – 30 MHz = 10 m 100 MHz = 3 m – 300 MHz = 1 m – 1 GHz = 30 cm

9. EM and RF Fundamentals As can be seen from the previous slide these waves really form an entire continuous “spectrum” of electromagnetic energy known as the Electromagnetic Spectrum. This spectrum is depicted in the graphic to the right. In this course we will concern ourselves with the portion shown in green known as the “Radio Spectrum” or RadioFrequency (RF) Spectrum

10. RF FUNDAMENTALS Despite the previous graphic, Radiofrequency (RF) and microwave (MW) radiation are not strictly defined across all standards but for the purposes of this training and the NPS program we will consider these bands to be: RF: 3 kilohertz (kHz) - 300 gigahertz (GHz) MW: 300 MHz - 300 gigahertz (GHz) Thus sources in the entire RF band as described above will be of interest to us here at NPS in terms of inclusion in the RF Safety and Control program. Further delineation is made later in the training with regard to effects on human health within these bands. Note that while the Microwave band begins at 300 MHz, for practical purposes many Engineers consider Microwave to begin at approx 2 GHz

11. RF Radiation Spectral Bands ELF Extremely Low Frequency 0 - 3 kHz VLF Very Low Frequency 3 - 30 kHz LF Low Frequency 30 - 300 kHz MF Medium Frequency 300 - 3000 kHz HF High Frequency 3 - 30 MHz VHF Very High Frequency 30 - 300 MHz UHF Ultra High Frequency 300 - 3000 MHz SHF Super High Frequency 3 - 30 GHz EHF Extremely High Frequency 30 - 300 GHz

12. Module Two Potential Health Effects of RF Radiation

13. Ionizing vs Non-Ionizing Radiation Ionizing radiation, by definition, is radiation capable of ejecting electrons from atoms and molecules with the resultant production of harmful free radicals. There is a minimum quantum energy below which this disruption cannot take place. Since the human body is largely water, the water molecule is used to define this minimum level. Different reference sources give varying figures for this between 12 eV and 35 eV. The actual value does not matter for the purposes of this comparison. 12 eV corresponds to a wavelength of 1.03 × 10–7 m (103 nm) which lies just above the ultraviolet (UVc) part of the electromagnetic spectrum. The highest RF frequency considered in our program as mentioned on a previous slide is 300 GHz which corresponds to a wavelength of 10 – 3 m and lies in the EHF band of the radio frequency spectrum. If the calculation is done the other way round, 300 GHz corresponds to an energy of 0.00125 eV which, from the foregoing, is too small by about four orders to cause ionization. However, in radio transmitters using very high supply voltages, ionizing radiation in the form of X-rays can be produced and for this reason it should be clear that this ionizing radiation is not inherent in the RF energy but rather that both forms of radiation can co-exist inside equipment and the RF engineer or technician needs to be aware of the hazards involved.

14. Non-ionizing Radiation and Fields, 0 - 300 GHz Static Electric and Magnetic Fields Sub-Radio frequency Electric and Magnetic Fields (1 Hz - 3 kHz) Radio frequency and Microwave Radiation (3 kHz - 300 GHz) “ batteries ” to “ heat lamps ”

15. Typical RF Sources Firefly (0.0005 W) Door Opener/Key FOB/ Home WiFi Router (0.005 – 0.010 W) Police Radar (0.015 W) Baby Monitor (0.15W) Cellular Phone (0.6W) Microwave Radiation by Humans (3.5W) C.B. Radio (5W) Mobile Radio (150W) Microwave Oven (1400W) AM/FM Transmitter (5-50 kW) UHF Transmitter (120 kW)

16. RF HAZARDS While effects of long term exposure (chronic) to RF and MW radiation remains uncertain, the user should be aware that some studies have linked this chronic exposure to increased risk of the following : -Some forms of Cancer (tumor/leukemia) -Adverse reproductive outcome -Cardiovascular disease -Cataracts Short term direct (acute) exposure effects are better known and are covered in many of the subsequent slides within this module. Bottom Line: Clinical Studies have failed to show adverse health effects related to RF exposure below limits of IEEE. Takeaway – Know and observe your RF exposure limits !

17. Principal RF Energy Interactions with Humans Ionization, E > 12.4 eV Photochemical Interactions Atomic / Molecular Vibration “heating” Current Induction; “electro stimulation”

18. RF Hazards: Direct effects on People* (a) Thermal effects attributable to the heating of the human body due to the absorption of RF energy. At lower frequencies this includes heating due to excessive current densities in some parts of the body. (b) Shocks and burns which may result from contact with conductive objects, e.g. scrap metal, vehicle bodies, etc., located in electromagnetic fields. (c) The so called ‘athermal’ effects, if any, where it is postulated that the fields act directly on biological tissue without any significant heating being involved. * RF and Microwave Radiation Safety Handbook – Pg. 52

19. RF Hazards: Direct effects on People There is general agreement that the main demonstrable effect on the human body above about 100 kHz is the thermal effect, i.e. the transfer of electromagnetic field energy to the body. A very high percentage of the human body is made up of water and water molecules which are polar molecules are influenced by impinging electromagnetic fields. Those tissues having a significant water content are most liable to be influenced by fields. Some other tissues also have large polar molecules. The effect of RF on such body tissues is to cause polar molecules to attempt to follow the reversals of the cycles of RF energy. Due to the frequency and the inability of the polar molecules to follow these alternations, the vibrations lag on them, resulting in a gain of energy from the field in the form of heat which causes an increase in the temperature of the tissue concerned.

20. RF Hazards: Indirect effects on People RF Energy can also have an indirect effects on people wearing implantable devices such as heart pacemakers, insulin pumps, passive metal plates and other related hardware due to interaction with some aspect of the implantable device. Some effects in this category affect the quality of life rather than physical health, e.g. interference with hearing aids and other electronic devices. Additional information is contained in the final module.

21. Absorption of RF Energy by the Human Body Biophysically the absorption mechanism can be divided into four ranges – 100 kHz to less than about 20 MHz: Absorption in the trunk decreases rapidly with decreasing frequency and significant absorption may occur in the neck and legs. – 20 MHz to 300 MHz: Relatively high absorption can occur in the whole body, and to even higher values if partial body (e.g. head) resonances are considered. – 300 MHz to several GHz: Significant local, non-uniform absorption occurs. – Above about 10 GHz: Energy absorption occurs primarily at the body surface. Note: It is important to understand these distinctions because the exposure limits are also to some degree variable with frequency, limiting part of the body, and exposure group (i.e. general public vs workers whose jobs require them to be exposed occupationally to RF energy)

22. Absorption of RF Energy - SAR In order to finally get to an understanding of RF exposure limits it is necessary to understand the concept of Specific Absorption Rate or SAR SAR is used to quantify the rate at which RF energy is being absorbed in soft body tissue and is expressed in watts per unit mass of tissue, usually Wkg –1. So, for example, if it is known that the total power deposited in the standard man is 7W, then the average whole-body SAR is 7/70 Wkg –1 or 0.1 Wkg –1

23. Relating Absorption and Temp Rise in the Human Body A ‘worst-case’ expression to relate specific energy absorption and temperature providing that the effect of cooling is neglected is given by the t = J/(c × 4180) Where: t = temperature rise (C) J = specific energy absorption (Jkg–1) c = relative heat capacity (= 0.85) Hence, for example an SAR of 2Wkg –1 for 30 minutes will give a temperature rise of 1C, neglecting cooling.

24. Establishing Limits A rise in body core temperature of about 2.2 0 C is often taken as the limit of endurance for clinical trials For RF radiation purposes, a limit of an increase of 1 0 C in rectal temperature has often been postulated as a basis for determining a specific absorption rate (SAR) limit for human exposure. Most western occupational standards are based on an SAR of 4 Wkg –1 divided by ten to give a further safety margin. Thus the general basis for establishing a practical working limit is a SAR of approximately 0.4 Wkg –1 but in an attempt to standardize with international committees practical SAR limits been lowered to a maximum of 0.25 Wkg –1 @ 70 MHz.

25. Establishing Limits In considering the amount of energy absorbed by the human body, it is necessary to recognize that the percentage of incident radiation which is actually absorbed depends on frequency and the orientation of the subject relative to the field. The depth of RF penetration of the human body is also an important factor and varies considerably with frequency For example, as can be seen above, At the microwave end of the RF spectrum, deposition of energy is confined to the surface layers of the skin

26. Establishing Limits

27. Establishing Limits – Critical Organs It should be obvious from the previous discussion that since this development is based on absorption of energy by water molecules, those body parts and organs which contain large quantities of water (vice bone or some other material) are particularly susceptible to absorption heating and thus damage. From the thermal transfer point of view, the two organs which are considered more susceptible to heat effects than others are the eyes and the male testes. The production of cataracts in animal experiments using RF has been well established. It is thought that for human beings the frequencies most likely to cause cataracts lie between 1 and 10 GHz. Thus when using powerful sources in these ranges it is particularly important to not unnecessarily linger with your head or reproductive organs near these sources (e.g. by conducting repairs or trying to read find print on the sources while they are energized) Experiments with anaesthetized mice and rats showed that male sperm cells are depleted by exposure to SARs of about 30Wkg –1 and 8–10Wkg –1, respectively. While no specific guidelines apply the general principle of minimizing exposure always applies.

28. Establishing Limits There is a universally accepted statement about RF radiation work that People should NOT remain in a field which gives rise to a sensation of warmth even if the power density is within the permitted limits of a standard. It will be evident from the previous discussion that this does not guarantee that no harm has been incurred but is intended as an extra warning. At low frequencies, the penetration of RF in the human body may be such that much more of it will be below the skin sensors and there may not be any physical sensation of warmth. The prevention of internal damage has to be by the limitation of exposure but If you can feel yourself heating up – GET OUT OF THE FIELD

29. Module Three National, Navy, and NPS Standards and Limits for Use of RF Sources and Protection for Personnel

30. Standards for Human Safety and Limits In order to provide guidelines for RF Safety it is necessary to try and define safe transmission and exposure limits. These limits are then imposed by safety standards. In the world of RF there are many safety standards, to name a few: International Committee on Electromagnetic Safety (IEEE) International Commission on Non-Ionizing Radiation Protection (ICNIRP) Occupational Safety and Health Administration (OSHA) Federal Communications Commission (FCC) NAVAL SEA SYSTEMS COMMAND (NAVSEA OP 3565) U.S. Navy Space and Naval Warfare Systems Command – SPAWAR These standards and limits are important because they: Control the direct exposure to people to electromagnetic fields which might have direct harmful health effects Prevent the ignition of flammable vapors and explosive devices by RF energy Reduce interference from RF sources with critical equipment operation which if they were to malfunction in turn could harm human health or safety

31. NPS RF Safety Limits AT NPS We follow the limits established by NAVSEA which are technically reviewed by SPAWAR and are based on the IEEE standard, but are slightly more conservative in some areas. These limits for controlled (occupationally exposed workers) and uncontrolled (General Public) environments are given on the subsequent two slides. Also note that that IEEE replaced “uncontrolled limits” with “action levels” in 2005 but Navy standards still contain reference to “uncontrolled limits”. For purposes of the NPS RF safety program the two terms have essentially the same meaning although at NPS we will most frequently use “action levels” and “controlled limits” to set program guidelines in keeping with IEEE. Generally, from a biophysical safety limit standpoint we are concerned with limits based on power density to the body, because these limits are more intuitive than electric field or magnetic field limits. However, you should know that it is actually the electric or magnetic field which is measurable and these are the fields capable of doing biological damage if exceeded. Power densities are derived by modern measuring equipment based on measurement of the E or H field. Power density limits are highlighted in red on the next slide to draw your attention. Please note the averaging times. It is not intended that you memorize these limits but rather just give the following several slides on limits a good look so that you have a general understanding of your limits and stay times and how your body reacts differently in different regions of exposure.

32. PELs for Controlled Environments (Electromagnetic Fields) FREQUENCY RANGE (MHz) ELECTRIC FIELD STRENGTH (E) (V/m) MAGNETIC FIELD STRENGTH (H) (A/m) POWER DENSITY (S) E-FIELD, H-FIELD (mW/cm 2 ) AVERAGING TIME |E|, |H|, or S (MINUTES) 0.003-0.1614163(100, 1000000)‡6 0.1-3.061416.3/f(100, 10000/ f 2 )‡6 3-303-301842/f16.3/f(900/ f 2, 10000/ f 2 )6 30-10061.416.3/f(1.0, 10000/f 2 )6 100-30061.40.1631.06 300-3000-- f/3006 3000-15000-- 106 15000-300000-- 10 616000/ f 1.2

33. PELs for Controlled Environments (Electromagnetic Fields) Graphical Representation

34. PELs for Uncontrolled Environments (Electromagnetic Fields) FREQUENCY RANGE (MHz) ELECTRIC FIELD STRENGTH (E) (V/m) MAGNETIC FIELD STRENGTH (H) (A/m) POWER DENSITY (S) E-FIELD, H-FIELD (mW/cm 2 ) AVERAGING TIME |E|, |H|, or S (MINUTES) 0.003-0.1614614163163(100, 1000000)6 0.1-1.3461461416.3/f(100, 10000/ƒf 2 )6 1.34-3.0823.8/f16.3/f(180/ f 2, 10000/ f 2 )f 2 /0.3 3-30823.8/f16.3/f(180/ f 2, 10000/f 2 )30 30-10027.5158.3/ f 1.668 (0.2, 940000/ f 3.336 )30 100-30027.50.07290.230 300-3000-- f/150030 3000-15000-- f/150090000/f 15000-300000-- 10616000/ f 1.2

35. PELs for Uncontrolled Environments (Electromagnetic Fields) Graphical Representation

36. PELs (Con’t) Note that PELs change considerably by frequency range because biological damage mechanisms are highly frequency dependent. The next slide goes into a little more detail on why the limits appear to have 3 distinctly different regions. While it is not intended that you memorize the previous charts, it is imperative that you have a general idea of PELs, how they change with frequency, and be aware of the specific PEL for a given source if you will be working near that source while it is energized.

37. Why the Three Regions ? The differing shapes and slopes of the limits shown on the previous several slides are based on different absorption characteristics of the body as a function of wavelength > The length of the body – In this region, there is little absorption and a uniform or equal distribution of energy. The impedance of the body increases as the wavelength increases. Safety standards are based on shock or burn hazards rather than direct absorption. ~ = The length of the body – In this region, the absorption is highest and the energy is distributed unequally. Hot spots may be generated. < The length of the body – In this region, lower absorption of energy and heating confined to irradiated area.

38. Why 3 Regions (con’t)

39. Averaging Times For controlled environments, personnel exposure levels higher than those shown in the limits table are permitted if the average exposure, over a specified (6-minutes in most cases – see the tables for specifics) time interval, does not exceed the PEL. This concept is known as “time averaging” Time averaging should be consistent with all aspects of the appropriate exposure limits, e.g., peak values of the electric or magnetic fields, currents, or voltages. Time averaging requires the measurement of your time in the RF field and/or RF source “on time” to ensure that the allowable, time-weighted exposure does not exceed the applicable exposure limit. For example, the ratio of the time that an RF field source is active (on) to the total time (on-time plus off time) is the duty factor or duty cycle. The duty cycle allows calculation of the time-averaged exposure that may be compared with an exposure limit. While the use of time averaging is a legitimate approach to managing exposure of humans to RF energy, it is normally used only in occupational environments for personnel that have been appropriately trained in RF safety procedures, and this is how we apply time averaging at NPS.

40. Why Six Minutes ? The 6 minute time average is loosely based on research performed in the 60’s, dealing with the body’s thermoregulatory response time. During this research thermal equilibrium was reached in approximately 6 minutes for the considered exposures.

41. Time Averaging Practical Example The following example, representative of a common workplace safety concern, is provided to help you understand the concept of time-averaged RF exposure limits, as well as the method by which such limits are calculated. A worker wishes to conduct maintenance in an area close to a transmitting antenna. The radiated power density in the desired work area has been surveyed (measured) and found to exceed PEL by a factor of two. The transmitter cannot be silenced, nor can the transmitted power be reduced. Given the following conditions, determine if maintenance personnel can safely enter the area and, if so, for how long. Transmit Frequency is 200 MHz Transmitted Power Density (TXPD) is 2 mW/cm2 PEL at 200 MHz is 1 mW/cm2 Time Average Interval (TAI) is 6 Min Calculated Time Averaging Factor (TAF) = PEL/TXPD i.e. TAF = (1 mW/cm2)/(2 mW/cm2) = 0.5 Calculated new Time Average Interval (TAI’) TAI’ = TAF*TAF or (6)*(0.5), which equals 3 Min Based upon the above calculation, workers are permitted to conduct maintenance operations in the RF hazard area for 3 minutes, after which they must leave the area for a minimum of 3 additional minutes before returning.

42. Module Four The Structure of the NPS RF Safety Program and How You Interact With It

43. NPS RF Safety Program The NPS RF Safety Program attempts to identify all Sources capable of producing RF energy on the campus and then categorize them into one of four levels associated with increasing risk to the general public, occupational RF workers, the environment or other equipment. Additional information on the categories and actions associated with the sources and categories are contained on the next few slides

44. Controlled Sources at NPS Not all sources of RF energy at NPS are controlled and subject to the restrictions of the NPS RF Safety Program. In general NPS controls RF sources as follows (in each case the limit is that which the source is capable of producing at maximum output – determined by theory or actual source measurement as indicated):  Below Action Level (This is generally 0.2 x PEL but depends on the frequency – see limit graphs) - Not controlled or accounted for by NPS. Users should observe manufacturer’s and FCC instructions for use. This includes all sources with less than 5W output power (i.e. that present at the input to the radiating portion of the device)  Action Level up to just below PEL - Inventory only. Generally no other controls on use or custody unless conditions change making the source capable of producing levels above PEL  1.0 – 5.0 x PEL – Annual inventory and inspection. RF safety program and training applies. SOP may apply. Some administrative and Engineering Controls may apply  Greater than 5.0 x PEL - Annual inventory and inspection. RF safety program and training applies. SOP mandatory. Most restrictive administrative and Engineering Controls

45. NPS RF Risk Categories

46. Risk Category Possible Actions These are intended to be illustrative of controls that will be reviewed and implemented on a case by case basis for RF sources by associated risk categories.

47. The RF Safety Program at NPS The RF Safety Program at NPS consists primarily of the following program elements Inventory of all potentially hazardous RF sources on the NPS campus Evaluation and categorization of all RF sources on the NPS campus Authorization of Radiofrequency Principle Investigators (RPI) to hold and use certain RF sources. – RPIs are issued permits to have custody and use CAT 2, 3, or 4 RF sources for research and teaching on the NPS campus – RPIs are allowed to attach other Authorized Radiofrequency Users (ARU) to their permit once their training is complete and they have been issued a permit to use sources by the RF safety officer Authorization of ARUs Initial and Refresher Training for RPIs and ARUs Implementation of controls on Category 2, 3, and 4 RF sources – Includes in some cases access restrictions in order to protect NPS personnel and the general public Periodic inspections and audits of various aspects of the program by the RF Safety Officer and others Detailed information on these program elements can be found on the NPS RF Safety Website [Insert Website Link Here], in the NPS RF Safety program instruction, NAVPGSCOLINST 6055.11, or by calling the RF Safety Officer, Mr. Terry Wichert, at x2184.

48. Major Program Elements for Radiofrequency PIs (RPI) If you desire to have full time custody of and use controlled RF sources at NPS you need to attain designation as an NPS RPI. You may find the following major program steps to useful as a guide to designation – Complete NPS RF Safety Training (i.e. take this training and pass the quiz) – Provide an inventory of your sources to the RF Safety Officer (RFSO)(note that sources can be added directly via the inventory link on the NPS RF Safety Website) – Schedule an evaluation of your sources, lab spaces, research with the RF Safety Officer – Work with the NPS RF Safety team to establish SOPs (if required) and/or incorporate required controls for the use of the sources on the NPS campus or its remote locations – Receive your RPI Permit – Coordinate with the RFSO to attach additional controlled RF Sources or Authorized RF Users (ARU) to your permit as needed – Annually renew your permit through completion of a lab visit by RF safety personnel and completion of annual refresher training

49. RF Source Survey Guidelines If you are an RPI, your controlled RF sources will be surveyed upon inclusion in the program as mentioned on the previous slide. Sources generally need to be resurveyed under the following circumstances: – After service or modification – Nearby equipment perturbed – At RPI Request Waveguides, if present, should be checked for leakage with each operation of the RF source.

50. Major Program Elements for Authorized RF Users (ARU) If you desire to use controlled RF sources at NPS you will need to attain designation as an NPS ARU and you may find the following major steps to designation useful – Find an RPI with the source you wish to use. Only RPIs are allowed to have custody of controlled RF sources at NPS – Obtain permission of the RPI to be attached to his/her permit – Complete NPS RF Safety Training (i.e. take this training and pass the quiz) – Be issued an ARU certificate and get added to the RPIs permit – Complete any RF Source specific training that the RPI designates for use of his/her sources (e.g. at a minimum familiarization with the SOP and controls associated with use of the source(s)) – Go to Work as an ARU – Maintain certification by completion of annual refresher training

51. Module Five Standard Procedures, Controls, Warnings, and Signs

52. FAMILIARIZATION AND COMPLIANCE TO SYSTEM SOP SOP (STANDARD OPERATING PROCEDURES) Required for some systems that emit RF or MW radiation above PELs in an uncontrolled or controlled environments. SOPs can prevent casualty or injury by standardizing procedures and required safety controls. Controlled sources of RF energy at NPS are analyzed for the necessity of a system SOP at time of authorization. If your system has an SOP prescribed you will need to be familiar with its contents and requirements prior to use of the equipment. Certification of your understanding of the SOP contents is not part of this training. This certification is done by your PI prior to your first unattended use of the equipment

53. Warning Signs and their Meanings SignMeaning Likely dealing with a Category 2 or 3 RF source You are likely in an area where an RF emitter exists but is producing levels below the PEL up to 3 times PEL While this area is “safe” you should not loiter in the area unless you know for certain that the RF source is not energized. Additionally if the source is energized you should know and observe your stay times provided you are authorized access during energized operations.

54. Warning Signs and their Meanings SignMeaning Likely dealing with a potentially dangerous Category 4 RF source You are in an area where an RF emitter exists and is capable of producing levels 3-10 times the PEL You should not enter or remain in the area unless you are cleared for access to the area and are aware of the status of the source. Access during operation is very likely prohibited. Check with the RPI and consult the SOP hazard information prior to entry If entry is authorized during energized operations, note that this sign signifies shorter stay times than the “Notice” sign.

55. Warning Signs and their Meanings SignMeaning You are certainly dealing with a Category 4 RF source You are at the boundary of an area where a dangerous RF emitter exists, capable of producing levels > 10 times the PEL Entry in this area is strictly controlled and very likely prohibited while the emitter is operating. Lock-Out Tag-Out (LOTO) procedures are likely in effect for any entry REMAIN CLEAR AND/OR OR

56. Module Six Limiting your exposure to RF Radiation and What to do if you think you have been overexposed Unity 3 dBd 5 dBd

57. Typical Sources of RF MF and HF Radio Transmitters Radar Systems Magnetrons Mobile Phones or WiFi routers(although the radiated power is typically quite small in these devices and as such are not controlled sources at NPS) Microwave Ovens – Note: While these are considered relatively powerful sources of RF energy, the energy is all contained within an interlocked cavity and thus this are not controlled at NPS. If you suspect your microwave may be leaking call NPS RF safety for a free survey of the microwave Medical Therapy Equipment

58. Typical RF Sources at NPS – Spanagel Roof

59. Minimizing your RF Exposure Minimizing exposure to RF is done in the same way as for other sources of radiation. Namely: Time – Minimize the amount of time you are in an active RF field. Know and observe your stay times. Distance – Keep your body and critical organs as far from the source of the RF as your task allows. Additional detail on subsequent slides. Shielding – For powerful sources of RF, consider using a form of shielding for you or critical organs if you must work near the source while energized. Shielding while useful is not as widely used in the practice of RF safety as it is in ionizing radiation safety. Still it may be useful to shield powerful RF sources not only to protect people but to prevent interference with other sensitive electronics. NPS RF Safety program personnel can help you find an appropriate protective barrier.

60. Distance Distance requires a little further explanation. Like other sources of radiation you may have heard that RF antenna field strength follows the 1/r 2 or “inverse square” law. i.e.when you double your distance from the source, the field strength reduces by a factor of 4. This is in fact generally true for most antennas but only in the far field. Antennas radiate in three distinct regions as shown below: Far-Field (Fraunhoffer) Region: r > 2D 2 / – Where D is the largest linear dimension of the antenna – This is the region where the wavefront becomes approximately planar, – E and H are equal and inverse square law applies – The apparent gain of the antenna is a function only of the angle (i.e., the antenna pattern is fully formed) Radiating Near-Field (Transition region): /2  < r < 2D 2 / – The region between near and far field – E and H are equal, but inverse square law does not apply – The antenna pattern is not fully formed Reactive Near-Field: r < /2  – Gain is not a meaningful parameter here – E and H are not equal and inverse square law does not apply – When reactive components are 10% or more of radiating components it may cause error in field measurements (< /6  )

61. Distance (Con’t) In addition to having different regions, real antennas radiate in complex patterns that can vary considerably with time, temperature of equipment, stability of power supplies, atmospheric conditions, etc. This makes the prediction of PEL limit distances difficult at best. Still it is generally true that the once you are out of the reactive near field the strength of the field decreases with distance and decreases even more rapidly in the far field. This leads to some general principles Generally stay as far away from an RF source as the timely completion of your task allows. Know the operating frequency of your equipment, the theoretical transition points of the antenna radiation pattern, and the limits i.e. PEL Observe all posted warnings and observe PEL boundary lines – The PEL limit line R (m) can be estimated from the equation to right – A.G. = Antenna Gain in dB – Power is average and in Watts – PEL is in W/cm 2 Stay out of the reactive near field and the transition region whenever possible.

62. Additional Measures to Minimize your RF Exposure Knowledge – Know the status of the source (i.e. energized or not) and the strength of the field it is capable of producing State of the Source – Keep the source de-energized until you absolutely need it energized to do your work and then secure it as soon as possible. Radiate to dummy load if possible. If the source must be energized, train it away from you are working if possible. Use Lockout/Tagout where appropriate Use Standard Operating Procedures – Know and use standard procedures which were developed with an objective of minimizing exposure Observe all Administrative and Engineering Controls specified by the RFSO for the use of the source you are using Consider the use of area monitors or active monitoring with measuring instruments as you work so that you know the exact status of the field. Use measuring equipment with long probes to prevent having to expose portions of your body to the RF beam. Use Physical Barriers where/when appropriate Know and Observe Stay times and use Time Averaging principles Understand and Observe all Notice, Caution, Warning, and Danger Signs

63. RF and Medical Devices Some medical devices, such as cardiac pacemakers, defibrillators, and drug delivery systems can exhibit improper operation when subjected to strong RF fields. Devices and systems that are used external to the body can be substantially more susceptible to interference. Therefore potential proximity to strong RF sources for someone with such a medical device requires special considerations. If you have any sort of medical device that you use and/or wear regularly to maintain your health such as those above or others you feel might be questionable then you: Must inform the RFSO and your PI prior to engaging in work utilizing any controlled RF sources at NPS Will be required to discuss the device manufacturer's information with appropriate occupational medical personnel to resolve any questions concerning compatibility with the NPS RF work environment. RF safety personnel can help you schedule this examination with local occupational health professionals.

64. RF Energy and Ordnance Use of RF field producing equipment in the vicinity of ordnance requires special consideration. The next few slides are intended to give you a general understanding of the hazard but the Navy has developed an entire body of literature, and a special program for this circumstance. Detailed knowledge of the hazard and the program are required prior to using RF fields in the vicinity of ordnance. Additional details can be found in NAVSEA OP 3565 Vol 2 “Electromagnetic Radiation Hazards to Ordnance – HERO”

65. RF Energy and Ordnance - HERO Hazards of Electromagnetic Radiation to Ordnance or (HERO) is the program concerned with prevention of accidental ignition of electrically initiated devices (EID’s) in ordnance due to RF electromagnetic fields. HERO was established by the Navy in order to : Classify sources of RF energy operating near electrically initiated ordnance as HERO SAFE, HERO SUSCEPTIBLE, HERO UNRELIABLE, or HERO UNSAFE. Determine the safe separation distances for HERO UNSAFE, HERO UNRELIABLE, and HERO SUSCEPTIBLE ORDNANCE. Develop a set of operational HERO requirements so that some RF sources may be used safely near ordnance and restrict or prevent others through use of administrative or engineering controls.

66. RF Energy and Ordnance Electromagnetic radiation (EMR) hazards stem from the functional characteristics of electrically initiated ordnance. This EMR hazard is the result of absorption of electromagnetic (EM) energy by the firing circuitry of certain explosive ordnance. Consequently, the induced energy causes heating of the ordnance’s bridgewire and primary explosive with which it is normally coated. The ordnance may be accidentally initiated or their performance degraded by exposure to RF environments. In general, ordnance is most susceptible to RF environments during assembly, disassembly, handling, loading, and unloading. However, the HERO program (both surveys and testing efforts) covers exposure of ordnance to the Electromagnetic Environment (EME) levels that may provide vulnerability for each piece of ordnance from cradle to grave.

67. RF Energy and Ordnance THE NEED FOR HERO CONTROL Technological advances have resulted in the development of extremely powerful communication and radar equipment that radiate high levels of EM energy. These advances, coupled with the trend to use more sensitive, low-power electronic circuits in the design of ordnance systems call for a need to evaluation HERO virtually anytime you will work in and around or even remotely close to ordnance. Because of this if you think there is any possibility that HERO could apply to you while using your source – DON’T ASSUME HERO DOESN’T APPLY to you because of the strength of your source. If there is any doubt check with NPS RF Safety Personnel first, who can clear your operation as HERO safe prior to proceeding.

68. What To Do if you think you have been or are being overexposed to RF Energy Exit the RF field immediately or if unable to do so, call for assistance – As indicated in the health effects modules, RF exposure that you can feel is a result of acute rather than chronic exposure. When removed from the field, if your symptoms are the result of RF exposure, they should resolve quickly (e.g. feelings of uncomfortable warming should stop very quickly) Notify your PI and the NPS RFSO at your earliest convenience Seek medical attention and let the doctor know that you believe you were inadvertently overexposed to RF energy

69. Training Completion This completes your review of NPS RF Safety Training Slides To complete your training you now need to take and pass the RF Safety quiz. The quiz is taken online and is closed book on the honor system. It must be completed in the same browser session in which you began the quiz in order for your results to be recorded. The quiz is 20 multiple choice questions and passing score is 70%. The RF Safety Officer is automatically notified when a quiz is taken and will inform you of your results. You can find a link to the quiz on the NPS RF Safety Website here https://docs.google.com/forms/d/14zFVvg_TgBPD6XMZoBuNrL_Iv7f_ Mb9U8lgQav72lak/viewform?embedded=true or by e-mailing a request for the quiz to tswicher@nps.edu https://docs.google.com/forms/d/14zFVvg_TgBPD6XMZoBuNrL_Iv7f_ Mb9U8lgQav72lak/viewform?embedded=true