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DEVELOPMENT OF AN RF SAFETY PROGRAM AT A “REMOTE SITE”

Donald L. Haes, Jr., Ph.D., CHP

α

Presented to FLAAPM / FCHPS

November 13, 2015

I am a member of the International Committee on Electromagnetic Safety (ICES)

and the Institute of Electrical and Electronics Engineers (IEEE), including the

Standards Association (IEEE/SA). All opinions expressed in this workshop are my

own, and are not intended to represent those of ICES, IEEE, or the IEEE SA.

Don Haes

2

Lets go back to the early 1990s …

ANSI C95.1-1991 just released with two-tiered exposure limits; prior to that there was a single-tier with frequency dependent limit values.

Some concerns were raised about a “remote site with powerful radars blasting everyone on the soccer field.”

The site was under the direction of MIT’s Lincoln laboratory, but in the Republic of the Marshal Islands; Kwajalein Atoll.

2

Location of “remote site” 3

Kwajalein Atoll is a crescent loop of coral reef enclosing an area of 1,100 square miles ; the world’s largest lagoon. Situated on the reef are approximately 100 small islands with a total land area of 5.6 square miles. Kwajalein Island, the largest in the atoll, is one-half mile wide and three miles long (approximately 1.2 square miles in area). From Kwajalein Island to Roi-Namur, in the north, is about 50 miles.

5

Inhabitants of “remote site”? 6

Inhabitants of “remote site”!

U.S. Army Kwajalein Atoll (USAKA): The islands of Kwajalein’ and Roi-Namur host >2,400 residents (military personnel, Army civilians, contractor employees, tenants, and family members.

Home to (now) Ronald Reagan Ballistic Missile Defense Test Site at Kwajalein Atoll (RTS), operates as a subordinate command of the U.S. Army Space and Missile Defense Command.

Approximately 12,000 Marshallese citizens live within the atoll, with the majority living on Ebeye.

7

U.S. ARMY KWAJALEIN ATOLL

Inhabitants of “remote site”; USAKA

Kwajalein

Roi-Namur

6

Launch and tracking of space vehicles

The launch of Flight 5 of the SpaceX Falcon 1 rocket from Omelek Island on Kwajalein Atoll 7/13/2009. (Photo courtesy of USAKA/RTS).

9

For many years, KREMS has played a role in collecting data associated with intercontinental ballistic missile testing and space tracking Kiernan Re-Entry Measurement Site (KREMS) radars.

Inhabitants of “remote site”; civilian population 9

Ebeye

3rd island

11

“In one historic week, Jan. 29 to Feb. 4, 1944, with the most

powerful invasion force ever assembled up to that time, American

forces seized Kwajalein Atoll from Japan. The invasion of the

Marshall Islands, code named Operation Flintlock, served as a

model for future operations in the Pacific. The seizure of Kwajalein

Atoll was the first capture of pre-war Japanese territory and

pierced the Japanese defense perimeter, paving the road to Tokyo.”

12 Battle plans; circa 1942

RFR Sources at remote site? 14

Lincoln Space Surveillance Complex, Westford, MA

HAY

HAX

Zenith MISA MHR

Telescope/Laser

Lincoln Space Surveillance Complex Sensors*

Millstone UHF Radar (MISA)

Frequency: 440 MHz

Antenna Diameter: 45.5 m

Peak Power: 2.5 MW Beamwidth: 1.1°

Mission: Ionospheric Studies

(Incoherent Scatter)

Since: 1978 Zenith

MISA

Millstone UHF Radar (Zenith)

Frequency: 440 MHz


Peak Power: 2.5 MW Beamwidth: 0.6°

Mission: Ionospheric Studies

(Incoherent Scatter)

Since: 1962

* Courtesy: Millstone Hill Observatory MIT Atmospheric Sciences Group

14


Millstone Hill Radar (MHR) Frequency: 1.295 GHz


Peak Power: 2.5 MW

Sensitivity: 50 dB (0 dBsm @ 1000 km) Beamwidth: 0.6° Max.

Bandwidth: 8 MHz

Mission: Deep-Space Metric

Since: 1957 / 1962


15

MHR

Haystack LRIR (HAY) Frequency: 10 GHz

Diameter: 37 m

Peak Power: 250 kW

Sensitivity: 57 dB (0 dBsm @ 1000 km)

Beamwidth: 0.05°

Max. Bandwidth: 1 GHz

Mission: Radioastronomy/Satellite Imaging

Since: 1964

Haystack Auxiliary (HAX) Frequency: 16.7 GHz

Diameter: 12 m

Peak Power: 50 kW

Sensitivity: 39 dB (0 dBsm @ 1000 km)

Beamwidth: 0.1°

Max. Bandwidth: 2 GHz

Mission: Near-Earth Satellite Imaging

Since: 1993



HAY

HAX

16

RFR Sources at remote site! 18

ALTAIR: tracks ~1300

deep-space orbiting satellites every week.

TRADEX: became operational in

1962 but was not employed for

space missions until 1994 as a substitute for ALTAIR.

25.6 m (84’)

RFR Sources at remote site! 19

Millimeter-Wave (MMW) radar has the

world’s best range resolution radar, and

produces coherent, high-resolution data images of satellites.

ALCOR’s wideband capability was

adapted to satellite imaging and

pioneering work in developing techniques

and algorithms for generating and interpreting radar images.

13.7 m (45’)

12.1 m (40’)

The KREMS “Sensors”: 20

The KREMS “Sensors” Command: 21

Estimation of Potential RF Exposure Special Considerations

Use maximum power, and a pulse width and pulse repetition frequency that will most closely approximate the maximum rated duty factor.

Account for both horizontal and vertical antenna radiation patterns and the appropriate ground reflection factor for that frequency.

Account for axial rotation in azimuth (“spinning”) and elevation (“nodding”).

Assume transmit “on-time” at least the averaging time for the appropriate MPE for that frequency.

22

Complications: Which RF exposure Standard to use? 23

{PRIVATE Freq./Band P pk P ave USAKA 385-3 MASSACHUSETTS REGs. ANSI C95.1-1991

Name

(MHz)

ID

(MW)

(kW)

Restricted

(Ht > 55") (mW/cm2)

Unrestricted

(Ht < 55") (mW/cm2)

440 CMR 5.0

(Workers) (mW/cm2)

105 CMR 122

(Public) (mW/cm2)

Controlled

(Workers) (mW/cm2)

Uncontrolled

(Public) (mW/cm2)

ALTAIR 162 VHF 7.0 100 1.62 1.0 1.0 0.2 1.0 0.2

ALTAIR 422 UHF 5.0 250 4.22 1.41 1.41 0.28 1.41 0.28

TRADEX 1320 L 2.0 143 10 4.40 4.40 0.88 4.40 0.88

TRADEX 2950 S 1.15 20.2 10 5.0 5.0 1.0 9.83 1.97

ALCOR 5670 C 2.25 7.3 10 5.0 5.0 1.0 10 3.78

MMW 35000 Ka 0.034 3.4 10 5.0 5.0 1.0 10 10

* USAKA Regulation 385-3 for restricted areas (access controlled for the exclusion of people less than 144 cm (55”) in stature and unrestricted areas (access not controlled for the exclusion of people less than 144 cm (55”) in stature [USAKA 385-3 Appendix I], regardless of working status.

Conservatism Using Far Field Calculations 24

Estimation of Expected RF Field Strengths

Parabolic Antenna - on axis

Reactive Near Field

Extends only to about ≈ λ / 2 π

λ = C / f {C = Speed of light in a vacuum (3 ∗ 108 m/s)}

25

Estimation of Expected RF Field Strengths (cont…)


26

Radiating Near Field (Fresnel Region)

The extent of the Radiating Near Field (Rnf) is:

Rnf = D2 / 4 ∗ λ

The maximum power density (Snf) in the near field is:

Snf = 16 ∗ P ∗ η = 4 ∗ P ∗ η D => Effective diameter of antenna

π ∗ D2 A A => Effective area of antenna

η => Antenna Efficiency (0.5-0.75)

P => Radiated power (Use Pave for personnel hazards

Note: If Snf < MPE, no need to continue.


Intermediate Field

The range of the Intermediate Field (Rif) is:

D2 < Rif < 0.6 ∗ D2

4 ∗ λ λ

The power density (Sif) at distance “r” in the intermediate field:

Sif = Snf ∗ ( Rnf )

r

27


Parabolic Antenna - on axis Far Field Region (Fraunhöfer Region) Note: The phase and amplitude do not

change appreciably with distance. The field has a plane-wave character.

The Far Field Region (Rff) begins at:

Rff > 0.6 ∗ D2

λ

The power density (Sff) at distance r is (use basic inverse-square function):

Sff = G ∗ P = A ∗ P

4 ∗ π ∗ r2 (λ ∗ r)2

Where: G = Antenna gain

P = Effective generated power

A = Effective area of antenna

r = Distance from antenna

28


ICES/NCRP Rpt #119 S = P ∗ G 4 ∗ π ∗ R2

or:

S = EIRP 4 ∗ π ∗ R2

Where: S = power density (in appropriate units, e.g. mW/cm2). P = power input to the antenna (in appropriate units, e.g., mW). G = power gain in the direction of interest relative to an isotropic radiator. R = distance to the center of radiation (appropriate units, e.g., cm). EIRP = equivalent (or effective) isotropically radiated power. Notes: 1. Use reflection factor of 22 (4) to be conservative, or 1.62 (2.56) for FM frequencies. 2. May use information from antenna radiation patterns if known.

29


Gain The Gain (G) is the absolute gain expressed as a power function.

Numerically, the Gain is:

G = 10gain/10

If the gain is unknown, it can be closely approximated by:

G = 4 ∗ π ∗ A ∗ η

λ 2

30


Scanning Correction

Large scanning angle ( φ ):

S = 4 ∗ P ∗ D ∗ 360

π D2 2 π r φ

For

φ ≥ D ∗ 360

2 π r

31


Scanning Correction

Small scanning angle (Θ ):

S = 4 ∗ P

π D2

For

Θ < D ∗ 360

2 π r

32


Non-Parabolic Antenna

Radiating Near Field

Rnf = G ∗ λ

4 π r2

Far Field

Rff ≥ 0.6 ∗ G ∗ λ

π r2

Note: Calculate S as before

33


Antenna Patterns 34

10dB

10dB

Vertical (“E”) Radiation Pattern Horizontal (“H”) Radiation Pattern


Calculations of Specific RF Safety parameters Each Major RF Source (“Sensor”) 35

Use formula for power density calculation.*

Use appropriate MPE value for frequency band.

Plug and chug; plot values in “percent MPE” over distance. When using MPE(lower tier), distance at 100%MPE represents

distance beyond which nothing would be REQUIRED. When using MPE(upper tier), distance at 100%MPE represents

distance beyond which documented RF safety training and awareness is REQUIRED, and but within which documented RF exposure mitigation is employed.

* Use appropriate ground reflection factor

Results of ONE RF Sensor: ALTAIR 36

Results of ONE RF Sensor: ALTAIR 37

Obstacles for RF Safety Calculations 38

Each Sensor can rotate 180° and transmit below 0° in elevation; Altair to -9°.*

There is a complex local-knowledge-ONLY convoluted “sector-blanking” protocol used to software-prohibit transmissions in certain “sectors” between particular azimuths (e.g. the “flight” sector).

Too many variables for a single plot; need multiple plots.

What about aircraft?

* “Hard stops” (removable bolts) installed to halt the dish at -2°; electronic stops need to be inhibited to transmit below 10°.

38

Aircraft / Sensor Encounter Scenarios

Significant Encounter Scenarios

KREMS Sensor:

Low elevation.

Stationary beam.

Aircraft:

Slow level flight with heading close to sensor line-of-sight (LOS).

Crossing beam at close range or hovering within beam.

39

38

Aircraft & Sensor “Features” KREMS Sensors

Narrow beams

Pulsed

High peak powers

Limited operating hours

Aircraft

Fixed-wing

Single-engine (low speed, short range)

Rotary-wing

Hover in proximity to sensor

39

Aircraft / Sensor RF Exposure Calculation

FIXED-WING

Set beam-crossing angle (), cross-over range (R0), and groundspeed (v).

Compute beam transit average power flux(S), transit time (Ttransit).

Adjust for radar duty cycle (D).

Scale for 30-minute averaging time.

1800,,,, 0030

transittransit

TDvRSvRS

R0

RL

OS

v

RLOS

crossover

(t)

t < 0

< 0 t > 0

> 0

No aircraft structure shielding effect assumed

40

Aircraft / Sensor RF Exposure Calculation

ROTARY-WING

Set position (x,y,z) and dwell time (Tdwell).

Compute power flux (S) at position.

Adjust for radar duty cycle (D).

Scale for 30-minute averaging time.

R0

RL

OS

v

RLOS

crossover

(t)

t < 0

< 0 t > 0

> 0

1800,,,,30

dwelldwell

TDzyxSzyxS

No aircraft structure shielding effect assumed

41

Near-Field Analytic X-Z Map 42

FIXED-WING AIRCRAFT

Exposure levels below C95.1-1991 (public).

Worst-case conditions examined:

Near-stall groundspeed.

Flight-path/RLOS angle only 3°.

Transit of near-field hotspot.

No aircraft structure shielding.

Aircraft / Sensor RF Exposure Conclusions 43

Rotary-wing Aircraft

Exposure levels can exceed C95.1-1991 (public).

Hover must be within antenna cylinder.

Some cases within only a few meters of RLOS.

Dwell for more than ~30 seconds.

FAA Notice to Airmen (NOTAM)

Aircraft / Sensor RF Exposure Conclusions 44

Have THEM get RF field measurements… 46

TRADEX

ALCOR MMW

ALTAIR

MT


Technical Considerations to Consider Prior To Obtaining RF Field Measurements

Calculate averaged and PEAK rated power prior to onsite measurements.

Obtain BOTH E and H field measurements 100-300 MHz UNLESS it can be shown the RF field can be properly characterized with one probe.

Use lowest power, and a pulse width and pulse repetition frequency that will remain within the maximum rated load of the equipment (e.g., the probe!).

Remember the probe “sees” the PEAK field, while it shows you the RMS field.

47


KREMS Sensor Information:

48

Sensor Name.

Operating Frequency (wavelength).

“Dish” characteristics:

Diameter. Gain. Vertical and horizontal radiation patterns.

Peak Power (PPk) and modulation characteristics.

Pulse Width. Pulse Repetition Frequency.


KREMS Sensor Information:

49

CACLUATE:

Extent Of Near Field (R NF).

Maximum Power Density Expected In The Near Field (S NF).

Range At Which Maximum Near Field Power Density Is

Achieved (R pk).

Beginning Of Far Field (R ff).

Power Density At The Beginning Of The Far Field (S @ R ff ).

KREMS Sensor RF Safety Information 50

Sensor

Name

f

(MHz)

Band

ID

Diam.

(m)

Gain

(dB)

λ

(m)

P pk

(MW)

P ave

(kW)

R nf

(m)

S nf

mW/cm2

R pk

(m)

R ff

(m)

S @ Rff

mW/cm2

ALTAIR 162 VHF 45.7 34.7 1.85 7.0 100 282 14.34 226 677 5.03

ALTAIR 422 UHF 45.7 42.4 0.711 5.0 250 735 36.58 588 1763 11.13

TRADEX 1320 L 25.6 48.2 0.227 2.0 143 721 69.94 577 1730 26.35

TRADEX 2950 S 25.6 54.2 0.102 1.15 20.2 1611 13.99 1289 3867 4.20

ALCOR 5670 C 12.1 55.0 0.0529 2.25 7.3 692 12.52 553 1660 5.48

MMW 35000 Ka 13.7 70.1 0.00857 0.034 3.4 5474 4.07 4379 13138 1.18

MMW 95000 W 13.7 70.1 0.00314 0.005 0.5 14937 0.814 11950 35849 0.032

51 Perspective … Altair VHF

Name R nf (m) R ff (m)

ALTAIR VHF 282 677

52 Perspective … Altair UHF


ALTAIR UHF 735 1763

53 Perspective … Tradex S


TRADEX S 1611 3867

54 Perspective … MMW Ka or W


MMW-Ka 5474 13138

MMW-W 14937 36849

55

R nf R pk R ff

Name (MHz) λ (m) ID (m) mW/cm2 %MPE (Cont) %MPE (Uncont) (m) (m) mW/cm2 %MPE (Cont) %MPE (Uncont)

ALTAIR 162 1.85 VHF 282 14.34 1434% 7170% 226 677 5.03 503% 2515%

ALTAIR 422 0.711 UHF 735 36.58 2594% 13064% 588 1763 11.13 789% 3975%

TRADEX 1320 0.227 L 721 69.94 1590% 7948% 577 1730 26.35 599% 2994%

TRADEX 2950 0.102 S 1611 13.99 142% 710% 1289 3867 4.2 43% 213%

ALCOR 5670 0.0529 C 692 12.52 125% 331% 553 1660 5.48 55% 145%

MMW 35000 0.00857 Ka 5474 4.07 41% 41% 4379 13138 1.18 12% 12%

MMW 95000 0.00314 W 14937 0.814 8.1% 8.1% 11950 35849 0.032 0.32% 0.32%

Sensor Frequency S nf S @ Rff

Sensor

KREMS Sensor RF Safety Information

KREMS Sensor RF SAFTEY CHALLENGES 56

MOST (if not all) locations will present near field conditions of non-uniform fields.

Will have to use much lower power levels and or duty cycles to prevent probe overload.

Will be challenged by setting anticipated field levels high enough to be detected above the probe “thermal drift” (ambient temperatures 95-100°F) at each frequency band.

Will have to use shaped probes only to account for multiple frequency environments.

Measurement Quantification Factors

Most all standards are based on the far field relationships and their interaction with the body.

Near field exposures are difficult to measure and almost impossible to calculate (simply), because of mutual coupling effects.

SAR is impossible to practically measure.

57

The solution …

Measure the Electric Field (E) in V/m;

Measure the Magnetic Field (H) in A/m;

Measure the Power Density (S) in mW/cm2;

Then compare those field results to published “limit” values that,

under maximal absorption conditions, would result in an SAR of no

more than 0.4 W/kg for controlled environments, or 0.08 W/kg for

uncontrolled environments.

58

59 Let’s go to Kwajalein…

60 Perception is underrated

Calculation – vs. Measurement?

EVERYONE believes a measurement …

EXCEPT the person who made it.

NO ONE believes a calculation …

EXCEPT the person who did it.

61

… a matter of perception

Travel to Kwajalein is no easy task …

Typical Itinerary

Up at 4 am to get to airport by 6 am for a 8 am flight to points VERY WEST.

Arrive at Honolulu airport 12 hours later to Hawaiian hospitality.

Up at 4 am to get to lobby at 5 am to get to Hickam field by 6 am to muster at the gate at 7 am for an 8 am Military Air Command (MAC) flight to US Army Kwajalein Atoll (USAKA).

Arrive at USAKA 6 hours later to US Army hospitality.

62

Last leg from Kwajalein to Roi-Namur*

Typical Itinerary

Once cleared through USAKA; get onto “flight list” to take the last 50 mile flight up the lagoon to the Islands of Roi-Namur; the main site of Sensor and control.

Arrive at Roi and settle into to VIP accommodations.

63

* NO GUARANTEE YOU MAKE IT THERE WHEN YOU WANT TO

This isn’t Kansas … 64

Japanese HQ, Kwajalein Gun Emplacement Japanese Cemetery

Wasn’t all work … 65

Swimming Exploring

Unexploded Shells

9 Hole Golf Course 19th Hole

Preparation for RF Field measurements 66

RF Measurements

RF Safety measurements focus on trying to determine RF field levels under conditions that are anything but controlled.

Output levels vary over time.

Multiple emitters and modulation schemes.

Reflections from towers, buildings, and the ground.

Field interactions.

Influence of the surveyor and the instruments.

67

Spatial Averaging

Measurements are averaged over an area equivalent to the vertical cross section of the human body.

SAR limit based on average energy absorbed over the body.

The limbs can tolerate higher levels since the body’s circulatory system acts as a coolant with the remainder of the body functioning as a radiator (20:1).

Basic Limit apply for the eyes and testes due to poor blood flow of these organs.

68

Shape Orientation and Polarization

Human body in a vertical position absorbs 10 times more energy in a vertically polarized field than in a horizontally polarized field.

Similarly, a prone body in a horizontally polarized field also absorbs the most energy.

69

Time averaging Exposure

• Because the primary effect is thermal, exposure is averaged over time. • In most standards, the averaging time is six minutes (controlled), which

is close to the thermal regulatory response time of the human body. • There are also limits on the peak exposure levels:

Transmitted Power • Pulsed System: Duty cycle = (PW ∗ PRF) • Rotating Antennas: TD = (ΘAZ ∗ 60)/(360° ∗ n); in seconds

70

Σ Sexp ∗ texp = Slimit ∗ tavg

Where: Sexp = power density level of exposure (mW/cm2), Slimit = appropriate power density MPE limit (mW/cm2),

texp = allowable time of exposure for Sexp, and

tavg = appropriate MPE averaging time

Compliance in a Multi-Signal Environment 71

Figures courtesy of NARDA

Determination of Type of Probe/Meter

Frequency: If multi-frequency, use broadband true root mean square (rms).

Response Time (< 3s desirable).

< 1s for detecting intermittent fields.

Recording or averaging capabilities for fluctuating fields.

Peak limitations (> factor of 10).

Polarization (isotropic, maximum deviation < 1dB).

Non-linearity (< 20%).

Other:

Temperature sensitivity (< 1dB, 0 - 130°F) and zero drift (< 10% per hour).

Battery life (if DC, > 8 hours) and response due to supply voltage (< 20%).

Susceptibility to RFI (minimum).

Weight; durability; ease of use.

72

RF Measurements: Safety Precautions

Care should increase in proportion to power level.

Precautions are different for deliberate radiating system surveys than leakage surveys.

Use estimation calculations.

73

Formula for HP15C Field-work 74

RF Measurements: Indirect Hazards

High Voltage (HV): Shock hazards.

Prime RF-leakage source may be HV electrodes of transmitting

tubes.

X-Rays: Survey for x-rays first; beware of RF interference.

DC magnetic fields.

Indirect RF Hazards: Electroexplosive devices (EEDs), flammable

materials, pacemakers, prosthetic implants, computers.

Burns: RF, thermal (hot and cold).

Abnormal modes of operation.

75

RF Measurements: Radiating Hazards

MPE: may use lower PPk, then extrapolate to higher power levels; limit exposure, duration.

Moving antennas.

Theoretical RF patterns.

Metallic structures and reflectors.

76

RF Measurements: Leakage Surveys Waveguides and coax

Set scales at MPE.

Beware of leakage ports.

Interlocks

Do not defeat interlocks on doors/panels.

Check operation by surveying with port closed, then open.

Foreign objects.

Inspect flexible waveguides.

77

Flexible Waveguide Failure 78

RF Measurements: Procedures Far-Field, Single Source

Scanning: Scan area of interest along axis of propagation.

Fixed Point (> 20cm from object):

Survey along > 8-10 evenly distributed points per wavelength.

Average over maxima and minima. Spatial average over the plane occupied by the body.

Account for reflections from support structures:

Perform either scanning or fixed multiple point surveys over several wavelengths along the axis of propagation.

Vary the distance from probe to support structure, while keeping the distance from the source to probe constant.

79

RF Measurements: Procedures

Complex Far-Field Sources

Use broadband isotropic probe.

Account for reflections by performing a scanning survey.

Beware of cable reflections and pick-up.

80

RF Measurements: Procedures

Near Field Conditions/Non-Uniform Fields

Normally use isotropic probe.

Perform a series of continuous scans.

Map the fields over the area of interest.

Make use of spacers

81

RF Measurements: Unique Problems

Extremely Low Frequency (ELF) and Very Low Frequency (VLF) Interference: Perform survey with instrument and probe in the same hand.

Cover probe with Sn/Cu/Al-foil or Narda “sock” to check for ELF/VLF.

Perform ELF, VLF survey.

Environmental Considerations: Outdoors: temperature, humidity, precipitation.

Indoors: cleanrooms, radioisotope laboratories, security clearance restricted areas, surgery rooms.

Height: towers, rooftops.

Traffic: sidewalks, highways.

82

RF Measurements: What to Measure?

IEEE Std C95.1™-1991 COMPLIANCE

f = 100 kHz to 110 MHz: RMS induced and contact current

limits for continuous sinusoidal waveforms.

f = 0.1 – 100 MHz: Both magnetic and electric field strengths

must be obtained.

f = 100 – 300 MHz: Both magnetic and electric field strengths

should be ascertained, but may be able to quantify the fields

with only the E field.

f = 300 MHz – 300 GHz: Plane wave power density.

83

RF Measurements: Units? 84

Electric, magnetic, EM, & dosimetric quantities and corresponding SI units

Quantity Symbol Unit

Conductivity F siemens per meter (S/m)

Current I ampere (A)

Current density J ampere per square meter (A/m2)

Frequency f hertz (Hz)

Electric field strength E volt per meter (V/m)

Magnetic field strength H ampere per meter (A/m)

Magnetic flux density B tesla (T)

Magnetic permeability µ henry per meter (H/m

Permittivity ε farad per meter (F/m)

Power density S watt per square meter (W/m2)

Specific energy absorption SA joule per kilogram (J/kg)

Specific energy absorption rate SAR watt per kilogram (W/kg)

RF Measurements: GAME PLAN ALTAIR 85

UHF and VHF combined and separate. E field evaluation each location with Narda 8718 meter

with 8722 E field probe. H field evaluation each site for (VHF) with Narda 8731

and 8754 H field probes.

Verify main lobe, side lobes, and back lobes.

Confirm predictive levels.

“Spot check” residence dwellings and airport.

RF Measurement Locations: ALTAIR 86

RF Measurement Locations: ALTAIR 87

RF Measurement Locations: MMW/TRADEX/ALCOR 88

RF Measurements: RESULTS 89

Survey Measurement: ALTAIR VHF & UHF Combined @ 2°

Distance from Sensor Raw Meter Reading (%MPE(Occ))

Extrapolated to Full Power

Predicted Maximum (%MPE(Occ))

600' 13.14% 26.75% 36.59%

550' 23.61% 48.06% 65.75%

500' 25.80% 52.51% 71.85%

450' 47.10% 95.87% 131.17%

400' 53.70% 109.30% 149.55%

350' 45.60% 92.82% 126.99%

300' 37.50% 76.33% 104.43%

250' 48.60% 98.92% 135.34%

200' 83.40% 169.76% 232.26%

150' 70.50% 143.50% 196.33%

100' 46.80% 95.26% 130.33%






600' 13.05% 25.56% 36.34%

550' 15.15% 30.84% 42.19%

500' 11.94% 24.30% 33.25%

450' 45.30% 88.54% 121.14%

400' 38.70% 78.88% 107.77%

350' 27.90% 56.79% 77.70%

300' 57.00% 116.02% 158.74%

250' 45.60% 92.82% 126.99%

200' 60.90% 123.96% 169.60%

150' 26.70% 54.35% 74.36%






600' 11.61% 23.63% 32.33%

550' 9.29% 18.81% 25.73%

500' 15.87% 32.30% 44.20%

450' 20.91% 42.56% 58.23%

400' 23.25% 47.32% 64.75%

350' 18.90% 38.47% 52.63%

300' 38.10% 77.55% 106.10%

250' 53.70% 109.30% 149.55%

200' 36.00% 73.28% 100.25%

150' 46.50% 94.56% 129.50%

100' 69.30% 141.06% 192.99%

Conclusions of Initial RF Field Measurements

There are accessible areas where an uninformed person could receive an exposure to RF energy in excess of human limits.

Although OSHA did not require RF Safety Programs (at the time), USAKA did have some safety rules regarding RF safety.

There is need for a comprehensive RF Safety Program specific to the Kwajalein Atoll complex.

92

93 Safety programs must effectively communicate RISK

RF “CAUTION” sign on Roi-Namur (circa 1990) “CAUTION” sign on Mt. Wilson warning of climbing over cliffs (courtesy Ric Tell), NOT RF

from nearby towers.

“All of us is smarter than any of us”

Ric Tell (Richard Tell Associates) hired as consultant on the project.

94

Basics of an RF Safety Program

RF hazard identification and periodic surveillance by a competent person.

Identification and Control of RF Hazard Areas.

95

Essentials of an RF Safety Program

Implementation of controls and SOP’s to reduce RF exposures to levels in compliance with applicable guidelines.

RF safety and health training to ensure that all employees understand the RF hazards and control methods used.

Employee involvement in the structure and operation of the S&H Program.

96

Essentials of an RF Safety Program (cont.)

Implementation of an appropriate medical surveillance program (Implanted Medical Devices (IMDs).

Periodic (e.g., annual) reviews of the program to identify and resolve deficiencies.

Assignment of responsibilities, including adequate authority and resources to implement and enforce the program.

97

Extent of RF Safety Program

Locations were categorized based on potential RF exposures.

Many RF exposure situations required no, or a limited RF Safety Program (Lower tier categories).

More extensive program elements for higher exposure potential (Higher tier categories).

98

Based on Potential for RF Exposure

Core Program Elements

Administrative

Identification of Potential Hazards

Controls

Engineering

Administrative

Personal Protective Equipment (PPE)

Training

Program Review

99

Core Program Elements: Administrative

Policy

• Management Commitment

• Authority to enforce rules

Accountable Persons

• Assignment of Duties

Documentation

Employee Involvement

RF Safety Committee

Procurement of RF Source Equipment

100

Core Program Elements: Identification of Potential Hazards

Inventory of RF Sources.

RF Exposure Assessment:

Establish exposure categories.

Ensure controls are functioning.

101

Category of Areas

102

Category Number Potential RF Exposure Condition Controls Required

1 Lower (Public) Tier not Exceeded None

2 Lower (Public) Tier may be exceeded

but Upper (Worker) Tier not Exceeded

Signs, training

3 Upper (Worker) Tier may be exceed

unless controls implemented

Signs, specific training

4 > 10 X the Upper (Worker) Tier Signs, barriers

Core Program Elements: Controls

Engineering

Utilize equipment & site configuration to control hazard areas.

Access Restriction.

Maintenance of Controls.

103

Administrative

RF “Warning” Signs; what to post and where.

Access Restriction; with and without training

Work Practices.

Control of Power Source (LOTO).

Area Monitors.

Incident Response.

Medical Surveillance (e.g. IMDs).

Maintenance of Controls.

104 Core Program Elements: Controls

Personal Protective Equipment (PPE)

A PPE Program must ensure its effectiveness, including the proper selection of RF PPE within tested capabilities, and accessibility, use, & maintenance.

105

From Ric Tell

Core Program Elements: Controls

Core Program Elements: Training

What to teach?

Location of sources and potentially hazardous areas.

Health effects and safety standards.

Extent of exposures compared to standards and common sources.

Required SOP’s and controls.

Emergency procedures.

How to know when things are “abnormal”.

Optional controls employees may use.

106

Core Program Elements: Program Review

Adequacy of Program Design.

Program Implementation.

Interview employees.

What are the hazards and controls?

What steps have been taken to enforce the rules?

Determine what to change, add, and delete.

107

This was the “birth” of IEEE Std C95.7

IEEE Recommended Practice for Radio Frequency Safety Programs, 3 kHz to 300 GHz: IEEE Std C95.7™-2014.

IEEE Standards Coordinating Committee 39, sponsored by the IEEE International Committee on Electromagnetic Safety (ICES).

108

THANK YOU … Questions?

Ω

program at a remote site - hps chaptershpschapters.org/florida/pptd.pdfin the republic of the...

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