RF Safety Program

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RF Safety Program
- Guidelines for Compliance - Understanding
Site Requirements for Radio Frequency Electromagn
etic Fields Robert Langston Amateur Call W2ENY
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OVERVIEW

• Requirements
• Dates
• 1997 FCC 97-303 Order
• 1997 OET65 Guidelines
• Exposure Levels
• Antenna Proximity
• Exclusions and Compliance
• Control of Non-Conforming Sites

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REQUIREMENTS

• October 15, 1997
• All new, modified and renewal sites
• September 1, 2000
• All sites must comply
• Regions required to ensure compliance
• Comply with the spirit and precautions
  outlined in the standards
• Use common sense where not specific

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1997 FCC Order 97-303

• The standard sets RF Exposure Levels
• Occupational and General Public levels differ
• Limits are averaged exposure over time
• Shared responsibility for compliance in
  co-located sites

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FCC SPEC and ENVIRONMENTS

• Controlled Environment Limits
• Exposure at some level is possible
• Persons trained to know exposure is possible
• Uncontrolled Environment Limits
• Exposure at some lower level is possible
• General Population
• Oblivious to knowing theyre being exposed
• 1/5 the Controlled level

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1997 OET 65 Guidelines

• Evaluating Compliance with FCC rules
• Prediction Methods
• Multiple Transmitter Sites
• Sample Calculations
• Measurement Techniques
• Controlling Exposure

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EXPOSURE vs FREQUENCY
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RF Exposure and Absorption

• Maximum Exposure averaged over time
• Controlled 6 minutes
• Uncontrolled 30 minutes
• Exposure measured as
• Power Density (mW/cm²)
• Absorption measured as
• Thermal heating effect (Watts/Kilogram)
• Sites may include other signals

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ANTENNA PROXIMITY

• Behind the Antenna
• Front to Back ratio usually 30dB
• Factor of 1000 times
• Above, Below or Beside Antenna
• Signals are greatly reduced
• Isolated by 30 to 40dB
• Factor of 1000 or better

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TYPICAL ANTENNA

• This is a FRONT VIEW
• Mounted from back side
• Cables attach from back or bottom
• Antenna is Covered
• Fiberglass or Plastic
• NO ELECTRICAL SHOCK HAZARD
• NO EXPOSED ELEMENTS

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FRONT/SIDE VIEW

• Front to Back Ratio
• Side Nulls
• Over and Under Nulls
• Above, Below and Side signals are reduced

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Control of Fields

• Time Averaging
• Based on Transmit vs. Receive
• Duty Factors
• Spatial Averaging
• FCC Spec. is a whole body average
• Elevate or Re-Orient Antenna
• Boundary Restrictions
• Fencing, Signs and Access Control

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Duty Factor by Mode
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Averaging
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Averaging
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TriBander Estimates
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VHF/UHF Estimates
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Sloper
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RF SAFETY EQUIPMENT

• Personal Monitors
• Narda Survey Meter Model 8718
• E-Field Probe 8722B (0.3-300 Standard)
• Isotropic Polarizationless 300KHz thru 40GHz

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So What Happens If...

• FCC License Revocation
• Chance about Zero
• OSHA 300 Fine per offense
• Chance about Zero
• Public Liability / Lawsuit
• Do you love your neighbor?
• Does your neighbor need the money?