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RF Safety Program

RF Safety Program. - Guidelines for Compliance - Understanding Site Requirements for Radio Frequency Electromagnetic Fields Robert Langston Amateur Call W2ENY. OVERVIEW. Requirements Dates 1997 FCC 97-303 Order 1997 OET65 Guidelines Exposure Levels Antenna Proximity

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RF Safety Program

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  1. RF Safety Program - Guidelines for Compliance - Understanding Site Requirements for Radio Frequency Electromagnetic Fields Robert Langston Amateur Call W2ENY

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

  3. 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

  4. 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

  5. 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 they’re being exposed • 1/5 the Controlled level

  6. 1997 OET 65 Guidelines • Evaluating Compliance with FCC rules • Prediction Methods • Multiple Transmitter Sites • Sample Calculations • Measurement Techniques • Controlling Exposure

  7. EXPOSURE vs FREQUENCY

  8. 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

  9. 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

  10. 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

  11. FRONT/SIDE VIEW • Front to Back Ratio • Side Nulls • Over and Under Nulls • Above, Below and Side signals are reduced

  12. 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

  13. Duty Factor by Mode

  14. Averaging

  15. Averaging

  16. TriBander Estimates

  17. VHF/UHF Estimates

  18. Sloper

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

  20. 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?

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