radio frequency exposure and compliance issues for a shortwave may 2008

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Matthew W. Folkert, MSEEE Stephen S. Lockwood, P.E. dTR/H&D Joint Venture A Joint Venture of the Consulting Engineering firms of duTreil Lundin & Rackley and Hatfield & Dawson. Radio Frequency Exposure and Compliance Issues for a Shortwave May 2008. HCJB - Pifo, Equador. HCJB - Pifo, Equador. - PowerPoint PPT Presentation

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  • Radio Frequency Exposure and Compliance Issues for a ShortwaveMay 2008Matthew W. Folkert, MSEEEStephen S. Lockwood, P.E.dTR/H&D Joint VentureA Joint Venture of the Consulting Engineering firms of duTreil Lundin & Rackley and Hatfield & Dawson

    Hatfield & Dawson

  • HCJB - Pifo, Equador

    Hatfield & Dawson

  • HCJB - Pifo, Equador

    Hatfield & Dawson

  • Presentation OutlineScope of WorkExposure StandardsAnalytical WorkMeasurement ProgramFindings

  • Scope of WorkConduct a Maximum Permissible Exposure Evaluation (MPE) of All IBB Transmitting Facilities16 Shortwave and Mediumwave Stations WorldwideLimited to a SurveySafety Seminar and Plan

  • IBB Stations Worldwide

  • Schedule of Site VisitsDelano - 1998Greenville 2001Kavala, Rhodes & Kuwait - 2001Morocco - 2002Sao Tome - 2002Philippines - 2003Botswana - 2003Sri Lanka - 2005Germany 2006Tinian - 2007Thailand - 2008

  • Analytical WorkModeling Using NEC-2Curtain Antennas with Full Reflecting ScreenRhombic AntennasE and H Field 2 Meters Above Ground

  • Curtain Antenna : E-Field

  • Curtain Antenna : H-Field

  • Exposure StandardsIEEEC95.1-2005ICNIRP(International Committee on Non-Ionizing Radiation Protection)Guidelines For Limiting Exposure To Time-varying Electric, Magnetic and Electromagnetic Fields(up to 300 GHz)OET(FCC Office of Engineering & Tech.)Bulletin 65

  • IEEE Occupational Standards

    Hatfield & Dawson

  • IEEE Public Standards

    Hatfield & Dawson

  • RF Exposure MechanismsExposure to radio frequency (RF) fields results in the absorption of energy in the body The mechanism of this energy transfer is the body acting as an antenna or, for contact currents, a semiconductive load for an RF source (i.e.RF source can be a tower, antenna, guy wire, etc)

    Hatfield & Dawson

  • RF Exposure Mechanisms (continued)The direct result is RF currents flowing in the body If the currents are large enough the body temperature rises At a certain rate of energy absorption biological effects also occur

    Hatfield & Dawson

  • The Electromagnetic Spectrum

    Hatfield & Dawson

  • Measurement ProgramIEEE C95.3 Recommended Practice for the Measurements of Potentially Hazardous Electrical Fields RF and MicrowaveSpatial Averaged over vertical line from 0.2 m 2.0 m20 cm from any object

    Hatfield & Dawson

  • Spatial AveragingMeasure over the area of a Human Body

    Hatfield & Dawson

  • Equipment UsedNARDA Model 8718B Electromagnetic Radiation Survey Meter

    E-Field Probe: 8742H-Field Probe: 8732Both shaped probesConforms to IEEE Occupational Standard

    Hatfield & Dawson

  • Equipment UsedHoladay Contact Current Meter

    Clamp-on Current Transformer: HI-3702System Readout: HI-44161 mA to 1 A100 kHz to 100 MHz

    Hatfield & Dawson

  • Contact CurrentPhysical Contact with a Conductive Material

    Hatfield & Dawson

  • Typical Data Sheet

    Hatfield & Dawson

  • Findings Where would you expect to find high fields at a shortwave broadcasting facility?

    Hatfield & Dawson

  • Transmitter Building?

    Hatfield & Dawson

  • Control Room?

    Hatfield & Dawson

  • Switch Matrix?

    Hatfield & Dawson

  • Transmission Lines?

    Hatfield & Dawson

  • Baluns?

    Hatfield & Dawson

  • Antenna Ground Works?

    Hatfield & Dawson

  • Antenna Near Field?

    Hatfield & Dawson

  • Warning Signs

    Hatfield & Dawson

  • Conclusions Closer to ground of RF conductors the higher exposure levelUnder Baluns -Open Wire Transmission LineAntenna Ground WorksAreas in main beam of antennas for 100 kW or greater within 100 meters

    Hatfield & Dawson

  • Questions?Matt Folkert matt@dlr.com Stephen Lockwood - lockwood@hatdaw.comwww.dlr.com & www.hatdaw.com

    Hatfield & Dawson

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