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RF Safety Program - Guidelines for Compliance - Understanding

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Presentation on theme: "RF Safety Program - Guidelines for Compliance - Understanding"— Presentation transcript:

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 September 1, 2000
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

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


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 Above, Below or Beside 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 Spatial 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 ( % Standard) Isotropic Polarizationless 300KHz thru 40GHz

20 So What Happens If... FCC: License Revocation
Chance about Zero OSHA: $300 Fine per offense Public Liability / Lawsuit Do you love your neighbor? Does your neighbor need the money?

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