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RF Safety Overview for Installation/Services Personnel

Rooftop Wireless Base Stations

Paul A. TestagrossaAlcatel-Lucent – Wireless CTOInternational Telecommunication Safety Conference

Denver, CO Sept 14 – 16, 2010

Content

1. Introduction – Background & historical activity in wireless area

2. FCC RF Guidelines

3. Typical wireless base station configurationsTowersRooftopsAntennas

4. Antenna compliance boundary (exclusion zone)

5. Rooftop RF environmentMeasurement dataRF Personal Monitors

6. RF Signage

7. Conclusions

Presenter

Presentation Notes

Agenda Pages This page allows for the listing of the sections within a presentation.

Copyright © 2010 Alcatel-Lucent. All rights reserved.3 | International Telecommunication Safety Conference| Sept 2010

Introduction – Background & historical activity in wireless area

Presenter

Presentation Notes

Divider Section Break Pages Title block set 28/32pt Trebuchet white, flush left with text box positioned at, Horizontal 1.87” and Vertical 2.87” This slide is to be used to create Section Divider slides Please copy, paste and modify this slide to reflect your specific needs. It is not generated from a Master slide template


Background & historical activity in wireless area

Historically, Bell Labs philosophy has been to be proactive in ensuring the safety and compliance of our wireless telecommunication products and systems, including:

Satellite communications (satcom)

Point-to-point microwave radio (terrestrial radio)

Personal wireless communications (cellular)Leading roles in safety standard development for human exposure to electromagnetic energy

IEEE Int’l Committee on Electromagnetic Safety (ICES)

IEC TC106

Presenter

Presentation Notes

At Bell Labs during the early 80’s, documented exposure levels associated with point-to-point microwave and satellite communication systems to ensure compliance with applicable safety standards� We continued this approach into the early 90’s through today, documenting exposure levels associated with personal wireless communication systems or “cellular” systems to ensure RF safety compliance Crucial to activity in RF safety arena was Bell Lab’s active participation in standards committees developing both human RF exposure limits and also assessment techniques (analytical & measurement). The primary IEEE standard committee (various name changes over the years) is the International Committee on Electromagnetic Safety (ICES). Technical Committee 95 (TC95) develops standards for the safe use of electromagnetic energy (0 – 300 GHz)


Background & historical activity in wireless area

C95.1-2005 “IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz

C95.2-1999: “IEEE Standard for Radio-Frequency Energy and Current Flow Symbols" (Reaffirmed in 2005)

C95.3-2002: "IEEE Recommended Practice for Measurements & Computations of Radio Frequency Electromagnetic Fields with Respect to Human Exposure to such Fields, 100 kHz to 300 GHz“

C95.4-2002: "IEEE Recommended Practice for Determining Safe Distances from Radio Frequency Transmitting Antennas when Using Electric Blasting Caps“

C95.6-2002 “IEEE Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields, 0—3 kHz

C95.7 -2005: "IEEE Recommended Practice for Radio Frequency Safety Programs.“

http://www.ices-emfsafety.org/

http://www.ices-emfsafety.org/


FCC RF Safety Guidelines

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Presentation Notes



FCC RF Safety Guidelines – Part1 of Title 47 CFR Section 1.1310

FCC Limits for Maximum Permissible Exposure (MPE) - Occupational

Frequency (MHz)

100 1000 10000

Pow

er D

ensi

ty (μ

W/c

m2 )

100

1000

10000 850-900 MHz: ESMR, Cellular, GSM, LTE*MPE > 2800 μW/cm2 >1500 MHz: PCS, GSM1900, UMTS, AWS, LTE*

MPE = 5000 μW/cm2

700 MHz: LTE - MPE >2100 μW/cm2

5000

300 MHz

f/0.3 1500 MHz

Time averaging - 6-minSpatial Averaging


FCC RF Safety Guidelines


FCC RF Safety Guidelines - OET Bulletin 65

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Presentation Notes

Many of the individuals who reviewed and commented on the draft of OET Bulletin 65 were also members of IEEE ICES


FCC RF Safety Guidelines - Telecom Act of 1996

The Telecommunications Act of 1996 is the applicable Federal law with respect to consideration of environmental effects of RF emissions in the siting of wireless facilities. With respect to personal communication services, e.g., cellular, PCS, Section 704 of the Telecommunications Act of 1996 states the following:

"No State or local government or instrumentality thereof may regulate the placement, construction, and modification of personal wireless service facilities on the basis of the environmental effects of radio frequency emissions to the extent that such facilities comply with the Commission's regulations concerning such emissions."


Typical wireless base-station configurations

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Presentation Notes



Wireless base-station configurations - Towers

Antennas

Equipment huts


Wireless base-station configurations – Rooftop

Antennas

outdoor equipment cabinets – equipment huts


Wireless base-station configurations – Antennas

Omni-directional base-stationOmni-directional antenna (whip)

Isotropic antenna pattern

Sectorized base-stationdirectional antenna (panel)beam-type antenna pattern

Front plane (aperture)

Back plane


Wireless base-station configurations – Antennas

ISOTROPIC emission pattern Directional-type emission pattern


Antenna compliance boundary(standoff distance, exclusion zone)

Presenter

Presentation Notes



Antenna compliance boundary – directional antenna

Dup

Dfront

Ddown

Dback

Dside

Dside

General Public boundary

Occupational boundary

DsideDside

Dfront

Occupationalboundary

GeneralPublic boundary Antenna

AntennaDback

Specifications:Freq = 869 MHzAntenna length = 6 ftHBW = 650

Input power = 100 W

Occupational Compliance Boundary (Dfront) = 5.5 ft

General Public Compliance Boundary (Dfront) = 27.5 ft

zone around antenna beyond which the safety guidelines for worker or the general public are not exceeded


Antenna compliance boundary – directional antenna

ADD PLOT

Power Density (mW/cm2)

0.01 0.1 1 10

Hei

ght (

cm)

25

35

45

55

65

75

85

95

105

115

125

135

145

155

165

175

Cellular Radio Antenna - Spatial Average Measurements(input power normalized to 12 watts)

5 cm20 cm50 cm1 m

top of radome

bottom of radome

Spatial Average0.98 mW/cm2 @ 5 cm

0.37 mW/cm2 @ 20 cm0.16 mW/cm2 @ 50 cm

0.08 mW/cm2 @ 1 m

Presenter

Presentation Notes

When close to an antenna (within the near-field) – energy is concentrated along the antenna length, minimal energy emitted above, below


Rooftop RF environment

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Presentation Notes



Rooftop RF environment – measurements

To perform an accurate assessment and to determine compliance requires knowledge of:

Near-field region (fields are complex)

Far-field region (free-space region)

Instrumentation

Broadband (isotropic, datalogging)

Narrowband (frequency - identify sources)

Time Averaging

Spatial Averaging


Rooftop RF environment – measurement data

Cable-tray crossover platformMaximum level measured

1760 μW/cm2

Bottom of antenna (2ft above platform)70 μW/cm2

FCC Occupational Limit: 2700-5000 μW/cm 2

NOTE: Spatial and time averaging will further reduce levels to well

below FCC limits



test probe

Time (HH:MM)

Pow

er D

ensi

ty (μ

W/c

m2 )

1

10

100

1000

10000

4:30 pm 5:004:45

Minimum valuesAverage valuesMaximum values

Probe placed on equipment platform in front of cellular radio antennas

2900 μW/cm2 - Controlled/Occupational MPE at 869 MHz



test probe

Time (HH:MM)Po

wer

Den

sity

(μW

/cm

2 )

0.1

1

10

100

1000

10000

1:30 pm 2:451:45 2:00

Minimum valuesAverage valuesMaximum values

5000 μW/cm2 - Controlled/Occupational MPE at 1930 MHz

2:302:15

Probe placed between BTS equipment and antennas - both mounted on same steel dunage support

Outdoor equipment cabinets



Time (HH:MM)

Pow

er D

ensi

ty (μ

W/c

m2 )

0.1

1

10

100

1000

10000

12:30 pm 1:3012:45 1:00 1:15 1:45

Probe placed approximately 20 cm from edge of front face of panel antenna, 6 ft above rooftop

Min values

Avg values

Max values

5000 μW/cm2 - FCC Occupational MPE at 1930 MHz

Test probe



Time (HH:MM)

Pow

er D

ensi

ty (μ

W/c

m2 )

1

10

100

1000

FCC MPE - 2837 μW/cm2*

11:00 am 11:45 12:00 pm11:15 11:30

5000

Min valuesAvg valuesMax values

GSM850 and UMTS (3G)

Test probe

Presenter

Presentation Notes

TEANECK site


Rooftop RF environment – RF Personal Monitor

Wear the monitor properlyOn your torso – not lower than belt levelOutside your clothingFacing outward – clip toward bodyFace toward source



MONITOR WILL NOT DETECT SIGNALS FROM BEHIND•Monitor must face toward source•Do not remain motionless for extended periods if location of source unknown/questionable

+90/-65o

±90o



Do not panic if monitor alarmsWhen monitor alarms (audible/vibrator)

- Move out of immediate area

- Move to an area where monitor no longer alarms

10 50 20010020

% STD



Are antennas mounted above head height?

yes no

Can you maintainstand-off distances?

yes no

Can you confirm thatantennas are receive-only?

yes no

Can you power-downantennas?

yes no

Use personal monitoring

Power-down antennas

Maintain stand-offdistances

No otherrequirements

No otherrequirements

Are commercial broadcast antenna co-located?

yes no

Use personal monitoring

Visual Assessment Of Work Area



PERSONAL RF MONITORING PROVIDES:

real-time RF exposure information relative to limits

visual and audible indication of exposure levels

PERSONAL MONITORING IS NOT REQUIRED FOR EVERY WORK AREA –

REQUIRED WHEN:

visual assessment indicates COMMERCIAL BROADCAST ANTENNAS CO-LOCATED

And/Or

stand-off distances CAN NOT BE MAINTAINED and antennas CANNOT BE POWERED DOWN



Pros:Useful when worker can not determine antenna types at site and/or broadcast antennas at siteAlerts personnel of existing/elevated RF fieldsShaped frequency response to match FCC stdVisible level indicators (LEDs) Audible & vibration alarms

Cons:Limited receive angle – position of person and/or location on body can block “detection”ExpensiveRequires calibration (2 yrs)Can provide a false sense of securityNOT to be used to evaluate RF compliance

Pros & Cons


RF Signage

Presenter

Presentation Notes



RF Signage

DANGER & WARNING signs Reserved for situations where serious injury or

“death” can occur(TV Broadcast tower)

NOTICE signsStatement of policy

relating the safety of people/property

CAUTION signsIndicates potentially hazardous situations –

minor to moderate injury may occur


RF Signage

General PublicExposure

(safety factor of 50)

OccupationalExposure

(safety factor of 10)

10 x Occ Exp


RF Signage

INCORRECT use of signs


RF SignageINCORRECT use of signs

INCORRECT wording


RF Signage

CORRECT use of signs

Antennas behind RF transparent enclosure


RF Signage

CORRECT use of signs

Specify Work Practices


Conclusions

Presenter

Presentation Notes



Conclusions – Rooftop Wireless RF EnvironmentsRF environments where service/installation personnel have access must comply with FCC RF exposure limits for occupational exposure

time & spatial averagingtrained work force

Antennas used in rooftop installations, i.e., typically directional:most of energy emitted from antenna’s front surface – narrow vertical beamcompliance boundary (exclusion zone): for directional antennas – area in front of antenna & to a less degree, sides of antenna; areas above, below and behind of antenna are normally below FCC limits

RF instrumentation – broadband isotropic survey devices required for accurate assessment of complex RF environments & to determine compliance

RF personal monitors – pros & cons

RF Signage – Can be wrong!!!

TRAINING, training, training – this is the MOST important aspect of any RF safety program


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